CA2119484A1 - Optically anisotropic material, process for producing it, and retardation plate and liquid crystal display device using same - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
By using an optically anisotropic film having the optical axis substantially parallel to the normal line of the film and comprising a polymer of a liquid crystal oligomerhaving positive anisotropy of refractive index and showing nematic or smectic phase, or by lamining the optically anisotropic film and a trans-parent or semitransparent polymer film, or by combining the optically anisotropic film with a uniaxially oriented retardation film, it is possible to obtain a composite retardation plate with a large viewing angle, and this retardation plate can be applied to a liquid crystal display device.

Description

BACRGROUND OF THE INVENTION
The present invention relates to an optically anisotropic film made of an oriented polymerized liquid crystal oligomer (or this can be said hereinafter "liquid crystal oligomer polymer") or a composition thereof useful as a material of retardation film used for liquid crystal display elements and such, a process for producing such a film, a laminate of an optically anisotropic film and a base, a composite retardation film consisting of said laminate and a uniaxially oriented retardation film, and a liquid crystal display device using them.
The retardation film is a polymeric film having optical homogeneity and durability as well as uniaxial orientationl and commonly used as an optical compensator for improving displaying performance of liquid crystal display elements. Super twisted nematic (STN) type li~uid crystal display elements using such retardation films, although having many advantages such as light weighty small thickness and low cost, also had serious disadvantages such as small viewing angle and poor black and white display quality. These disadvan-tages have been significantly alleviated by introduction of new techni~ues such as two-layer lamination of the retardation f.ilms. However, as regards the viewing ~i ~f ~ ! f angle, no satisfactoxy improvement has been made, and also no established industrial method is yet available for controlling the viewing angle in certain f.~pecific directions.
T~e viewing angle characteristics of liquid crystal display elements are closely associated not only with angle dependency of birefringence of liquid crystal cell for display but also with angle dependency of retardation of retardation film, and it i~ known that in use of conventional retardation films, the smaller the angular change of retardation is, the better result is obtained. In view of this, it has been proposed to use homeotropically oriented liquid crystal material as a retardation film having a large refractive index in the direction normal o the film plane.
Japanese Patent Unexamined Publication (JP-A) 2~73327 and JP-A-2-105111 disclose methods using a birefringent layer in which the in-plane refractive index i6 isotropic but the refractive index in the thickness direction is-greater than the in-plane refractive index, for reducing ~he angular change of background color of the optically uniaxial birefringent body ~liquid crystal cell for display) having positive anisotropy of refractive index. A typical e~ample of material having such refrac~ive index anisotropy is a liquid crystal layer oriented homeotropically in a compensation cell.
U.S. Patent No. 5,189,538 teaches that by , . , ,. ~ . .. . - . . ~ . ..,. .. . - .

:.. ~ .. : . -: , ~ . :

.:: ~ . : ~ ~ . , ~J~"~

using a film having the optical axis in the direction normal to the film plane and a retardation film ha~ing a positive birefringence, it is possible to reduce the angular change of retardation and to obtain a retarda-tion film improved in viewing angle characteristics.
For making a film having the optical axis in the direction normal to the film plane, a method is shown in which a photopol~merizable compound and a liquid crystal monomer are mixed and polymerization is carried out while maintaining orientation of the liquid crystal monomer in an electric field to fix orientation in the direction normal to the film plane.
JP-A-4 16916 discloses a retardation film usin~ a birefringent layer in which the refractive index in the thickness direction is greater than the in-plane refractive index, said layer being made of a homeo-tropically oriented polymer liquid crystal material. As means for effectuating homeotropical orientation of the polymer liquid crystal, there are disclosed a method in which the material is heated to the liquid crystal temperature and then an electric or magnetic field is applied in the thickness dire~tion, and a method in which the material is held b~tween two pieces of sub-strate which have been ~ubjected to surface treatment with a homeotropic alignment agent such as a silane compound, and homeotropically oriented a~ the liquid crystal temperature. It is disclosed that a retardation film with excellent viewing angle characteristics can be ~: - . ~ : ..

obtained by combining said film with a retardation film obtained by stretching a polymeric mater.ial.
Pol~vinyl alcohol, which is a polymer having hydroxyl groups in the side chai.n, is used for pr~ducing the homogeneous alignment reagent for liquid crystal molecules in liquid crystal display devices, and it is known that the liquid crystal molecules on the film can be oriented homogeneously by rubbing the surface of the film formed on a transparent electrode substrate.
Digest of Technical Papers of Society for Information Display International Symposium (1993), page 277, .reports that it is possible to improve, in princi-ple, the viewing angle characteristics of TN liquid crystal display devices by using two optically aniso-tropic bodies in which the optical axis is slanted from the normal line of the film and an op~ically anisotropic body having the optical axis in the film plane.
F~r attaining orientation of the liquid crystal molecule~, a grea~ many attemp~s have been made and reported, reflecting the fact that orien~ation of the liquid crystal mole~ules in the display cell is a key factor for high display quality. In the case of low molecular ~eight liquid crystal, however, orienta-tion is usually controlled by usin~ an orientation film.
25 - For forming an alignment film, there are known, for example, a method in which, for obtaining homogeneous orientation, a polymer (such as polyimide) film is formed on a substra~e and the film surface is rubbed .: : ~. , .

with a cloth or other means to orient the liquid crystal molecules; method in which an inorganic m~terial such as SiO2, SiO, MgO or MgF2 is deposited on a substrate by oblique evaporation to form a homogeneous alignment film; and method using a stretched polymer film (Foundation and Application of Liquid Crystalt 1991, pp.
97-100, Kogyo Chosakai). There are also known methods for obtaining oblique orientation of low molecular weight liquid crystal. For example~ use of an organic alignment film made of polyimide or oblique evaporation o an inorganic material such as SiOz, SiO, M~O and MgOz are known. ~hese orientation films serve for uniformal-izing orientation of the liquid crystal molecules in the liquid crystal display elements or ior giving a pretilt ~o realize an e~cellent display image quality.
However, there is yet known no laminated polymer film comprising a liquid crystal oligomer and a hydrophilic su~strate in which the optical axis is substantially parallel to the normal line of the film.
In production of composite retardation films comprising 2 laminated film of a liquid crystal polymer and a polymeric substrate and a retardation film, there has been some difficulties ~o prepare ~ film having the optical a~is in direction ~ormal to the film plane in 25 - the conventional produc~ion methods; photopolymerization of monomeric liqllid crystal should be carried out during applying an external acting field such as an electric or magnetic field, or the liquid crystal layer should be . :, j . , ~ ~. ..

,.,. 1. .,. ~, ,i. . ..

held between two hydrophobic substrate~ and then separated from, while maintaining orientation of the liquid crystal monomer with larçle relaxation of orienta-tion for keeping the optical axi.s normal to the film plane. Thusl in case of using polymer liquid crystal, the method of orientation was complicate t and in case o using low polymer liquid crystal, fixing of orientation was difficult.
Further, as regards the production method of liquid crystal polymexs and liquid crystal oligomer films having the optical axis slanted from the normal line of the substrate, there has been known no other technique than to apply a holding electric field to a txansparent glass plat~ having electrodes for effectuat-ing orientation (40th Meeting of Japan Society ofApplied Physics, Spring l9g3, Lecture No. 29aZK-ll).
SUMMARY OF THE INVENTION
As viewed above, in the prior art, there has been available no established industrially advantageous method for production of liquid crystal polymers and films made thereof. The present invention is intended to provide an optically anisotropic film made of a liquid crystal pol~mer, a polymeriæed liquid crystal oligomer or a composition ~hereof with which a composite retarda~ion plate with a wide viewing angle can be made, an indu~trial production method of such film, a composite retardation plate wi~h a wide viewing angle obtained by laminating said film and a retardation film, and a liquid crystal display de~ice having excellent viewing angle characteristics realized by using said elements.
More specificallyt the present invention S provides an optically anisotropic film comprising a polymer of a liquid crystal oligomer having positive anisotropy of refractive index and showing a nematic or smectic phase, said liquid crystal oligomer baing selected from the linear-chain or cyclic liquid crystal oligomer~ principally composed of the following recurring units (I) and (II):

Rl- - (CH2~ O~-Ar~ L)-p Ar2- R ( I ) R2--1--( CH2 )k~ ( O )~ Ar3--( L ' )p, Ar4--OCO----CR'=CH2 (II) (wherein A is a group represen~ed by the following formula (III) or (IV):

-Si - tIII) --C - COO- (IV) C~2 wherein, in the formula (III), -Si-O- is the main chain of the recurring unit (I) or (II) and, in the formula (IV), -C-CH2- is the main chain of the recurring unit (I) or (II) and COO group is positioned at the side chain which is neither R~ nor R2; when A in the formula (I) or (II) i~ the formula (III~, Rl and R2 are indepen-dently hydrogen, C~6 alkyl group or phenyl group, and when A in the formula (I) or (II) is the formula (IV), Rl and R2 are independently hydrogen or Cl-6 alkyl group;
k and k' represent independently an integer of 2 to 10;
m and m' are independently 0 or 1; Arl, Arz, Ar3 and Ar4 represent independently 1,4-phenylene group, 1,4-cyclohexane group~ pyridine-2,5-diyl group or pyrimidine-2,5-diyl group; L and L~ represent indepen-dently -CH2O-, -O-CH2~, -COO-, -OCO-, -CH2-CH2-, -CH=N-, -N=CH- or a divalent group represented by the formula (V):

-N -- - (V) p and p' represent indepsndently a number of 0 or 1; R
is halogen, cyano group, C~10 alkyl group or C~10 alkoxy group; and R' is hydrogen or Cl_5 alkyl group), wher~in when the numbers of the recurring units (I~ and (II) in one molecule of said oligomer are supposed to be n and n~, respectively, n and n' are independently an integer of 1 to 20, and 4 c n ~ n~ < 21, and further character-i ~ ~ i i: : , i : . .

ized in that the end group of the recurring unit (II) is polymerized, and that the optical axis of said film is aligned generally in the direction of an angle selected from between 0 and 80 against the normal line of the film~
There are also provided according to this inven~ion: An optically anisotropic film of the type described above, characterized in that the optical axis of said film is aligned substantially parallel to the normal line of the film plane; and An optically ~nisotropic film of the type described above, characterized in that the optical axis of said film is slanted 10-80, in terms of angle of elevation, from the film plane.
The present invention also provides an optically anisotropic film made of a side chain ~ype liquid crystal polymer having positive anisotroply of refractive index and showing a nematic or smectic phase, said liquid crystal polymer being a linear-chain or cyclic liquid crystal polymer principally composed of the following recurring units (IX):

Rl- A - (CH2)k-(O)~ A~1- (L)p- AL2 R (I2) (wherein A is a group represented by the following formula (X) or (~

--Si-- (X) ~ C--COO--(XI) wherein, in the formula (x)~ -Si-O- is the main chain of the formula (IX) and, in the formula (XI~, -C CH2- is the main chain of the formula (I~) and C00 group is positioned at the side chain which is not Rl; when A in the formula (IX) is ~he fonmula (X), Rl is hydrogen, Cl6 alkyl group or phenyl group, and when A in the formula (IX) is the formula (XI), R~ is hydrogen or Cl6 alkyl group; k is an integer of 2 to 10; m is 0 or 1; p is 0 or 1; Arl and Ar2 represent independently 1,4-phenylene group, 1,4-cyclohexane group, pyridine-2,5-diyl group or pyrimidine-2,5-diyl group; L is -CH2-O-, -O-CH2-, -OCO-, -COO-, -CH2-CH2-, -CH=N-I -N=CH- or a divalent group represented by the formula -N - N-; and R is hydrogen, halogen, cyano groupy Cl~0 alkyl group or C1l0 alkoxy group), characterized in that the number of the recur-ring units is 4 to 10,000, on the average, per one molecule~ and that the optical axis of said film is slanted 10-80, in terms of angle o~ elevation, from the film plane.
The present invention further provides the processes for producing the above-describad optically anisotropic films.
The present invention also provides a laminate comprising an optically anisotropic film made from an optically anisotropic substance such as mentioned above and a hydrophilic substrate such as a transparent or semitransparent substrate.
The present invention fuxther provides a process for producing a composite retardation film, which comprises forming a film of a linear-chain or ln cyclic liquid crystal polymer composed of said recurring units (IX) and showing a nematic or smectic phase on an optically uniaxial retardation film having the optical axis in the film plane, said film also having positive refractive index anisotropy and made o a thermoplastic polymer, and heat-treating the thus obtained composite film at a temperature above ~he liquid crystal phase/
isotropic phase transition temperature of said liquid crystal polymer.
The present invention also provides a process for producing a composite retarda~ion film, which comprises forming a film of a linear-chain or cyclic liquid crystal polymer composed of said recurring units (IX) and showing a nema~ic or smectic phase on a sub-strate ha~ing a glass transition temperature higher than the liquid crystal phaseJisotropic phase transition temperature of said liquid crystal polymer, heat-treating the thus formed film at a tempera~ure above said liquid crystal/isotropic phase transition temper-ature, and laminating the substrate having a film of said liquid crystal polymer formed thereon and a uniaxially oriented retardation film having the optical axis in the film plane, said film also having positive anisotropy of refractive index and made of a thermo-plastic polymer.
The present invention furthex provides a laminate of an optically anisotropic film such as mentioned above and a substrate, in which said substr2~e is a uniaxially oriented retardation film having the optical axis in the film plane, said film also having positive refractive index anisotropy and made of a thermoplastic polymer, and said laminate having a refractive index satisfying the following formula (1):

~ ~ nz ~ ny (1) (wherein n~ and n~ are the maximum value and the minimum value, respectively, of the in-plane refractive index of the laminate, and nz is the refractive index in the thickness direction of the laminate), and a composite retardation plate made by using said laminate.
The present invention further provides a composite retardation film having a polarizing film attached thereto, characterized in that a polarizing film and said optically anisotropic film or said lami-nate of said optically anisotropic film and substrate or said composite! r~tardation plate are bonded to each other with a binder or an adhesive.
The present invention additionally provides a liquid crystal display device comprising a liquid crystal cell comprising a liquid crystal layer held between a pair of substrates provided with electrodes, said liquid crystal layer having positive anisotropy of refractive index and twist orientation torsionally, with the helical axis in the direction normal to the sub-strats when no electrical voltage is applied, character-ized in that at least one of said optically anisotropicfilm, laminate of said optically anisotropic film and a substrate and composite retardation film is pro~ided between said liquid crystal cell and a polarizing film disposed outside of said cell, or a composite retarda-tion plate ha~ing a polarizing film attached thereto isplaced on said liquid crystal cell.

BRIEF DESCRIP~ION OF THE DRAWINGS
Fig. 1 is a graph showing the relationship between retardation and inclination angle of a laminated film composed of a polymerized liguid crystal oligomer and a polymeric substance ob~ained in Example 1.
Fig. 2 is a schematic layout at the time of measurement of transmitted light quantity described in - Example 17.
Fig. 3 is a graph showing the relationship between inclination angle and transmitted ligh~ quantity under crossed nicols in Example 16.

.~;. ,1 .~ ,., i,~ , i :~

Fig. 4 is a graph showing the relationship betwe~n inclination angle and transmitted light quantity under crossed nicols in Example 17.
Fig. 5 is a drawing showing iso--contrast curves in Example 21.
Fig. 6 is a drawing showing iso-contras~
curves in Example 22.

DESCRIPTION OF THE PREFERRED EMBODIMENTS
In the course o the studies for overcoming said prior art problems, the present i.nventors found that b~ forming a film of a liquid crystal oligomer having positive anisotropy of refrackive index and showing a nematic or smectic phase by using said oligomer alone or together with a specific low-molecular weight compound and subjecting the formed film to a treatment for causing homeotropic alignment and then to polymerization, it is possible to attain fixation of film alignment. This technique makes it possible to obtain an op~ically anisotropic film having the optical axis substantially parallel to the normal line of the substrate plane on a hydrophilic substrate. It was also found that a liquid crystal polymex or a liquid crystal oligomer ha~ing positive anisotropy of refractive index and showing nematic or smectic phase can b oxiented with an inclination agains~ the normal line of the substrate plane on an oriented substrate. It was further ound that by o~bining an optically anisotropic :

'' l'~'; ''1'' i''i film such as described above and a uniaxially oriented retardation film, it is possible to obtain a liquid crystal display element having a high black and white display quality and excellent viewing angle character-istics. The present invention was attained on the basisof these novel findings.
Specifically, the present invention embraces the following embodiments (1) to (22) in its claimed scope.
(1) An optically anisotropic film comprising a polymer of a liquid crystal oligomer having positive refractive index anisotropy and showing a nematic or smectic phase, said liquid crystal oligomer being selected from the linear-chain or cyclic liquid crystal oligomers principally composed of the following recurring units (I) and (II):

R~- ~ (C~2)k (0)~ Arl (L)p - Ar2-R (I) R2--~(C~2)k' i)m~ 3--(L~ )p---Ar4--OtO--CR'=CH2 ( I I ) (wherein A is a group represented by the following formula (III) or (IV):

., . ~. ,- .. , j , . . . . .. . . .

,, ,1. '.1 ., i:(:

-Si - (III) ~ C- COO- (IV) O Cl H2 wherein, in the formula (III), -Si-O- is the main chain of recurring unit of the formula (I) or (II) and, in the formula (IV), -C-CH2- is the main chain of the recurring unit (I) or (II) and COO group is positioned at the side chain which is neither Rl nor R2; when A in the formula (I) or (II) is the formula (III), Rl and R2 are independently hydrogen, C~6 alkyl group or phenyl group, and when A in the formula (I) or (II) is the formula (IV), Rl and R2 are independently hydrogen or C16 alkyl group; k and k' represent independently an integer of 2 to 10; m and m' are independently Q or l; Ar~, Ax2, Ar3 and Ar4 represent independently 1,4-phenylene group, 1,4~cyclohexane group~ pyridine-2,5-diyl group or pyrimidine-2,5-diyl group; L and L' represent indepen-dently -CH2 0-~ -O-C~2-, -C~O-, -OCO-, -CH2-CH2 , -CH=~-, : -N=CH- or a divalent group represented by th~ formula (V3:

N - N- (V) p and p' are independently O or 1; R is halogen, cyano group, Cl10 alkyl group or CllO alkoxy group; and R' is hydrogen or Cl1o alkyl group), wherein when the numbers of the recurring units (I) and (II) in one molecule of said oligomer are supposed to be n and n', respecti~ely, n and n' are independently an integer of 1 to 20 and 4 <
n + n' ~ 21, and further charact:erized in that the end group of the recurring unit (II) is polymerized, and that the optical axis of said film is aligned generally to the direction of an angle selected from between 0 and 80 against the normal line of the film.
(2) An optically anisotropic film set forth in (1) above, said film being composed of a polymerized liquid crystal oligomer and a low-molecular weight compound, said lowmolecular weight compound being at least one member selected from the group consisting of the compounds of the following formulae (VI~/ (VII) and (VIII~

R3-Ar1- (L)p ~r2- R4 (~I~

(wherein Arl and Ar2 represent independently 1,4-phenylene group, 1,4-cyclohexane group, pyridine-2,5- :
diyl group or pyrimidine-2,5-diyl group, R4 is halogen, cyano groupl methacryloyl group, acryloyl group, 1-20 alkyl group or C1zO alkoxy group; L is -CHz-O-, -O-CHz-, -COO-, -OCO-, -CHz-CH2 , -CH=N-, -N=CH-, 1,4-phenylene group or a divalent group represented by the formula (V); p is 0 or 1; and R3 is C330 alkyl group or C330 alkoxy group) (R5 r~ I~Q (VII) (wherein R5 and R6 represent independently hydrogen, Cl20 alkyl group or C1zO alkoxyl group; and m and Q are independently 1 or 2) CH2=C(R7)-cOoRs (VIII) (wherein R~ is hydrogen or methyl group; and R8 is Cl30 hydrocarbon group) and the compo~ition of said film is 100 parts by weight 10 of said liquid crystal oligomer and 0.1-40 parts by weight of said low-molecular weight compound.
~3) An optically anisotropic film set forth in (1) or (2), characterized in that the optical axis of said film is aligned substantially parallel to the normal line of ~aid film plane.
t4) . An optically anisotropic film set forth in (1) or (2), characteriæed in that the optical axis of said film is inclilled 10-80, in terms of angle of elevation, from the film plane.
20 (5) An optically anisotropic film made of a side chain type liquid crystal polymer having positive refractive index anisotropy and showing a nematic or smectic phase, said liquid crystal polymer being a linear-chain or cyclic liquid crystal polymer composed of the following recurring units (IX):

Rl- A - (CHz)k (0)~ Arl--tL)p- Ar2- R (IX) (wherein A is a group represented by the following formula (X) or (XI):

-Si ~ (III) --C - COO- (IV) l~z wherein, in the formula (X), -Si-O- is the main chain of the recurring unit (IX) and, in the formula (XI)~
~C-CH2- is the main chain of the recurring unit (IX) and COO group is positioned at the side chain which is not Rl; when A in the formula (IX) is the formula (X), Rl is hydrogen, Cl~ alkyl group or phenyl group, and when A in the formula (IX) is the formula (XI), R~ is hydrogen or Cl-6 alkyl group; k is an integer of 2 to 13; m is O or 1; p is O or 1; Arl and Ar2 represent independently 1,4-phenylene group, 1,4-cyclohexane group, pyridine-.. ,:. - ~ . .: :. :
- :

2,5-diyl group or pyrimidine-2,5-diyl group; L is -CH2-O-, -O-CHz-, -COO-, -OCO-, CH2-CH2-, CH=N-, -N-CH-or a divalent group represented by the following formula--N = N-\0/

and R is hydrogen, halogen, cyano group, Cl10 alkyl group or Cl10 alkoxyl group), and the number of the recurring unit (IX) is 4 to 10,000, and further characterized in that the optical axis of said film is aligned generally to the direction of an angle selected from between 10 and 80 against the normal line of the film.
(6) A process for producing an optically anisotropic film set forth in (1), (2~ or (3), which comprises forming a film of a linear chain or cyclic liquid crystal oligomer composed of the recurring units (I) and (II) set forth in (1~, subjecting the formed film to a heat treatment so that the optical axis thereof is aligned subs~antially parallel to the normal line of the ~ilm, and then polymerizing the end group of the recurring unit (II).
(7~ A pxocess for producing an optically anisotropic f.ilm set forth in (13~ (2) or (4) which comprises forming a film of a linear-chain or cyclic liquid crystal oligomer compo~ed of the recurring units (I) and (II~ described in (1) on substrate subjected to an alignment treatment, subjecting the formed film to a heat treatment so that the optical axis of the film will be aligned 10-80, in terms of angle of ele~ation, ~rom the film plane, and then polymerizing the end group of recurring unit (II).
(8) A process for producing an optically anisotropic film set forth in (5), which comprises forming a film of a linear-chain or cyclic liquid crystal polymer composed of the recurring units (I~) described in (5) on a substrate subjected to an align-ment treatment, and sub~ecting the formed film to a heat treatment so that the optical axis of the film will be aligned 10-80, in terms of angle of elevation, from the film planeO
~9) A process for producing an optically anisotropic film set forth in (7) or (8), wherein the alignm~nt treatment of the substrate is to carry out oblique evaporation of an inorganic material.
(10) A laminate of an optically anisotropic film and a hydrophilic substrate, obtained by laminating an optically anisotropic film set forth in (1), (2) or (3) and a transparent or semitransparen-t hydrophilic substrate.
25 ~ A laminate of an optically anisotropic film and a hydrophilic substrate set forth in (10), wherein the substrate is a glass plate, a hydrophilic polymer iilm or a laminated film consisting of a hydrophilic polymer film and a transparent or semitransparent polymer film.
(12) A process for producing a composite retardation film, which comprises forming a film of a linear-chain or cyclic liquid c~stal polymer composed of said recurring units (IX) ancl showing a nematic or smectic phase on a uniaxially oriented retarclation film having the optical axis in the film plane, said film also having positive anisotropy of refracti~e index and made of a thermoplastic polymer, and heat-treating the formed film at a temperature above the liquid crystal phase~isotropic phase transition temperature.
(13) A process for producing a composite retardation film, which comprises forming a film of a linear-chain or cyclic liquid crystal polymer composed of said recurring units (IX) and showing a nematic or smectic phase on a substrate having a glass transition temperature higher than the liquid crystal phase~
isotropic phase transition temperature of said liquid crystal polymer, heat-treating the formed film at a temperature above said liquid crystal phase/isotropic phase transition temperature, and laminating the substrate having formed thereon a film of said liquid crystal polymer and a uniaxially oriented retardation 25 - film having the optical axis in the film plane and showing positive anisotropy of refractive index.
(14) A composite retardation film set forth in ~13), wherein the substrate is a polari~ing film.

.. .... . ..

,.,: :
-: . .. , .. .. . -. , . :~

(15) A laminate of an optically anisotropic film set forth in (10) and a substrate, said substrate being a uniaxially oriented retardation film having the optical axis in the film plane/ said film also having positive fractive index anisotropy and mad~ of a thermoplastic polymer, wherein t:he fractive index of said laminate is defined by the following formula (1):

n~ > n~ > ny (1) (wherein nx and ny are the maximum value and the minimum value, re~pectively, of the in-plane refractive index of the laminate, and nz is the refractive index in the thickness direction of the laminate).
(16) A composite ~etardation plate obtained by laminating a unia~ially oriented retardation film having the optical axis in the film plane, said film also having positive anisotropy of refracti~e index and made of a thermoplastic polymer, and a laminate of an optically anisotropic film set forth in (10) or (11) and a hydrophilic substrate, wherein the refractive inde~ of said ~omposi~e retardation plate is defined by the following formula (1):

- nX ~ nz > n9 (1) (wherein nX and n9 are the maximum ~alue and the minim~m value, respectively, of the in-plane refractive index of the composite retardation plate, and nz is the refractive inde~ in the thickne~s direction of said laminated composite retardation plate).
(17) A laminate of an oriented liquid crystal polymer film and a substrate, said film compri~ing a laminate of an optically anisotropic film set forth in (4) or (5) and a transparent or semitransparent substrate, on which an aligNment treatment is carried out.
(18) A laminate of an optically anisotropic film and a substrate set forth in (17), said sub~trate being a uniaxially oriented ret~rdation film ha~ing the optical axis in the film plane, said film also having positive refracti~e index anisotropy and made of a thermoplastic polymer.
(l9) A composite retardation plate obtained by laminating a uniaxially oriented retardation film having the optical axis in the film plane, said film also having positive refractive index anisotropy and made of a thermoplastic polymer, and a laminate of an optically anisotropic film and a substrate set forth in ~17).
(20) A polarizing film~incorporated composite retardation film characteri~ed in tha~ a polarizing film and an op~ically anisotro~ic film set forth in any of (1) to ~5) or a laminate of an optically anisotropic film and a substrate set forth in any of (10) and (15 to (18) are bonded to each o~her with a binder oæ an adhesive t or a composite retardation plate set forth in -~ ~q.,!,.;`,L,L"~,,,,,"I

(16) or ~19) are bonded to each other with a binder or adhesive.
(21~ A liquid crystal display device characterized in that at least one of an optic:ally anisotropic film set forth in any of (1) to (5), a laminate of an optically anisotropic film and 2 substrate set forth in any o (10) and (15), (17) and (18) and a composite retardation plate set forth in (16) or (19) is provided between a liquid crystal cell and a polarizing film disposed outside thereof, said liquid crystal cell comprising a liquid crystal layer held by the substrates having the electrodes, said layer having positive dielectric anisotropy and twistedly oriented 90 to 270 with the helical axis aligned vertically to the substrate when no voltage is applied, or a polarizing film-incorporated composite retardation film set forth in (20~ is disposed on said liquid crystal cell.
(22) A liquid crystal display device in which at least one of an optically anisotropic film set forth in any of (1) to (5) and a laminate set forth in any of (10), (15), (17) and ~18) is provided between a liquid crystal cell and a polarizing film disposed outside thereof, said liquid crystal cell comprising a homo-geneously oriented nematic liquid crys~al having positive dielectric anisotropy and held by the sub-strates provided with the electrodesl said nematic liquid crystal having its major molecular axis aligned substantially horizontally to the substrate when no voltage is applied.
(23) A laminate comprising a polymer substrate and an aligned polymerized liquid crystal oligomer film set forth in abo~e (1), said polymer substrate being obtained by subjecting a surface of transparPnt or semi-transparent polymer substrate to hard coat treatment.
(24) A laminate set forth in above (23), wherein the substrate is a uniaxially oriented retardation film having an optical axis in a film plane, having positive anisotropy of refractive index, and made of a thermo plastic polymer, and said laminate having a refractive index ~atisfying the following formuila (l):

n~ > nz > n~ (1) wherein n~ and n9 are the maximum value and the minimum value, respectively, of the in-plane refractive index of the laminate; and nz is the refractive index in the thickness direction of the laminate.
(2S) A composite-retardation plate comprising a uniaxially oriented retardation film having an optical axis in a film plane, ha~ing po~itive ani~otropy of refractive index and made of a thermoplastic polymer, and a laminate set forth in above (23) comprising an aligned polymeri~ed liquid crystal oligomer film and a substrate, and said ~omposite retardation plate ha~ing a refractive inde~ satisfying the following formula ~l)s nx ~ nz > ny (l) wherein n~ and l~y are the maximum value and the minimum value, respectively, of the in-plane refractive index of the composite retardation plate; and nz is the refrac-S tive inde~ in the thickness direction of the compositeretardation plate.
(26) A liquid crystal display device comprising a liquid crystal cell comprising a liquid crystal layer held between a pair of substrates prov.ided with electrodei, said liquid crystal layer having positive anisotropy of refractive index and twist orientation torsionally with a helical axis in the direction normal to the substrates when no electrical voltage is applied, a pair of polarizing films being provided outside the electrode substrates, and at least one member selected from the group consisting of (a) a laminate comprising an aligned polymerized liquid c~ystal oligomer film and a ~ubstrate set forth in above ~23) or ~24~, and (b) a composite retardation plate set forth in above (25) ~eing placed between the electrode substrates and ~he polariiing films, respectively.
(27) A liquid crystal display device set forth in above (26), wherein at least one member ~elected from the group consisting of (a~ a laminate comprising an 2S aligned polymerized liquid crystal oligomer film and a substrate set forth in above (24) and (b) a composite retardation plate set forth in above (25) is used, and the aligned polymerized liquid crystal oligomer film being placed between (A) a uniaxially oriented retardation film constituting the laminate or the composite retardation plate and having positive anisotropy of refractive index, and (B) a polarizing film.
(28) A liquid crystal display device comprising a pair of transparent substrates having electrodes thereon and sandwitching a liquid crystal cell containing a nematic liquid crystal layer having positive dielectric anisotropy and oriented substan-tially horizontally with a helical axis torsionally aligned ~ertically to ~he substrate when no voltage is applied, a pair of polarizing films positioned outside a pair of the transparent electrodes, and at least one uniaxially aligned retardation film having positive anisotropy of refractive index and made from a thermoplastic polymer positioned between the liquid crystal cell and at least one of the polarizing films, and at least one layer of optically anisotxopic film set forth in above (1), (2) or (5) being present bet~een the liquid c~ystal cell and at least one of the polarizing films.
(29~ A liquid crystal display device comprising a pair of transparent substra~es havin~
electrodes thereon and sandwitching a liquid crystal ~: .
- : . ...

3: i cell containing a nematic liquid crystal layer having positive dielectric anisotropy and homogeneously oriented in the almost horizontal direction when no voltage is applied, and a pair of polarizing films positioned outside a pair of the transparent electrodesl and at least one layer of the optically anisotropic ~ilm set forth in above tl), ~2) or (5~
being present between at least one of the polarizing films and the liquid crystal cell.
The present invention is further illustrated below.
The liquid crystal oligomer composed of the recurring units (I) and (II) and the liquid crystal pol~mer composed of the recurring units (IX) used in the present invention are a side chain type li~uid crystal oligomer and a side chain type li~uid crystal polymer which ha~e positive anisotropy of refractive index and assume a nematic or smectic phase in the state of liquid crystal. The backhone of the side chain type liquid crystal oligomer or polymer is constitllted by, for exam-ple, a poly-l-alkylacrylic acid ester or a polysiloxane.
Such an oligomer or polymer may be of a linear-chain or cyclic structure. In the case of li~uid crystal oligomer, however, the cyclic structure is preferrsd because of better chemical stability. Preferred examples of poly-l-alkylacrylic acid esters usable for said purpose are polymethacrylic acid esters and - 3~ -polyacrylic acid esters, the former bein~ more preferable. Among these side chain type liquid crystal oligomers or polymers, those of the polysilo~ane basis are preferred. There is generally used one in which the group closely related to liquid crystalline property (which group may hereinafter be referred to as mesogen group) is bonded to the backbone through a folded chain (which may hereinafter be referr~ed to as spacer).
The length of the spacer, type of mesogen group and pol~merization degree of the side chain type liquid crystal oligomer or polymer used in this inven~
tion are preferably ~o selected that the transition temperature from liquid crystal phase to isometric phase (which may hereinafter be referred to as liquid crystal phase/isometric phase transition temperature) will become 200C or below, preferably 170C or below, more preferably 150C or below, for facilitating drying at the time of lamination on the substrate or ~rientation treatment.
The side chain type liquid crystal oligomer us~d in the present invention needs to be oriented so as to give po~itive aniæotropy of refractive index to ~he filmt and the number of recurring units is an important factor for facilitating this operation. Too large a number of recurring units leads to a high viscosity and a high li~uid crystal transition temperature, which necessitates a high temperature and a long time for orientation, w]hile too small a number of recurring :.. : : :

d -- 31 ~
units may cause relaxation of the orientation under around room temperature. The numbers n and n' of the recurring units (I) and (II) are each an integer of 1 to 20, and they are selected so that n ~ n~ = 4 to 21. In view of orientation characteristics and fixation of orientation after polymerization, khe n : n' ratio is pre~erably in the range f rom 1 s 5 to 5 : 1, more preferably 1 : 3 to 3 ~ he n/n' ratio may be properly adjusted when synthesizing the liquid cry~tal oligomer as described later.
In the case of the side chain type liquid crystal polymer composed of the recurring units (I~), the polymerization degree should be 4 to 10,000, preferably 4 to 1,000, more preferably 4 to 21.
The liquid crystal transition temperature and orientation characteristics of the side chain type liquid crystal oligomer or polymer are also affected by the spacer connecting the mesogen group to the backbone.
Too short a ~pacer deteriorates the orientation charac-teristics of mesogen group, while too long spacer tends to cau~e relaxation of orientation. ~herefore, as ~pacer, alkylene group or alkyleneoxy group with a carbon nu~ber of 2 to 10 is preferred. C26 alkylene or alkyleneo~y group is especially preferred because of 2S easier orientation. For facilitation of synthesis, alkyleneoxy group is more preferred. Typical examples of the preferred groups are: -(CH2)2, -(CH2) 3- ~ - ( CH2~ 4-~(CH2)s~~ -~CH7)6-, -(CH2~3-O-,-(CH2)4-O-, -(CH2)5-O- and ,.,, L .

-(CH2)6-O-.
It i~ desirable that oriented liquid crystal oligomer film of this invention has positive anisotropy of refractive index, and for this reason, mesogen group used in this invention is preferably one which has positi~e anisotropy of refractive inde~. The structures which can provide such mesogen group include those of the oligomers composed of the recurring units (I) and (II) wherein Ar1, Ar2, Ar3 and Ar4 represent indepen-dently 1,4-phenylene group, 1,4-cyclohexane group, pyridine-2,5-diyl group or pyrimidine-2,5-diyl group.
They also include the structure in which th~ divalent group L connecting Arl and Ar2 or Ar3 and Ar4 is -CHz-O-, -O-CH2-, COO-, -OCO-, -CH2-CH2-, -CH=N-, -N=CH- or -N - N-, and the structure in which Ar1 and Ar2 or Ar3 and Ar4 are directly bonded. More preferably, Ar" Ar2, Ar3 and Ar4 are independently 1,4-phenylene group, pyridi.ne-2,5-diyl group or pyrimidine 2,5-diyl group, most preferably 1,4 phenylene group. Preferably the connecting groups L and L~ are independently -CH2-CH2-, -COO- or -OCO-, more preferably -COO- group.
The group R in the recurring units (I~ and (IX) influence~ dielectric anisotropy or orientation performance of mesogen group, so that R is selected from halogen, cyano group, C~10 alkyl group and Cl10 alkoxy group, preferably cyano group, Cl10 alkyl group and Cl10 alkoxy group, more preferably cyano group, for obtaining . , , . .. ,. ,.. , ., , ~ , , .. . . .. - . .

~ 33 a liquid crystal oligomer ox liquid crystal polymer film with strong anisotropy of refractive index.
The terminal group of the recurring unit (II) is a group for fixing orientation of the liquid crystal oligomer by polymerization. Po:Lymerizable groups usable in this inYention are those of the formula -OCO-CR'-CH2 (R~ is hydrogen or Cl5 alkyl group), which include acrylate groups and methacrylate groups. The polymer-ization method of these groups is not specified, but usually photopolymerization or thermal polymerization using a radical polymerization initiator is employed.
Photopolymerization is preferred for easiness of operation and high orientation fixing eficiency. Known photopolymerization initiators can be used.
Examples of the nonpolymerizable mesogen groups usable for the linear-chain or cyclic liquid crystal oligomers composed of the recurring units (I) or the linear-chain or cyclic liquid crystal pol~mers composed of the recurring units ~I~ are shown in Tables 1-4.

.. .. ::: .: :-: .. : :~ : , : , . . : . . :- :.:

: :: - . .

: . . . . ~ , : . ~ ..

~ ~:

= = _ , - .. - -u~
:~ ~D ~ 0~ ~ O ~ O
l ... ....... _.. _ o ~ u~ 'I 1` ~ o~ u~ ,1 1~ ~ a~
3 ~1 ~1 ~ ~ ~ ~ .J U7 Vl _ ......
o ,_ ~, O ~D ~ 0 ~ O U~
~ m~ ,, ,, c~ ~ ~
~ _ .. ~,. .
U~ l m~ ~
~, _ m~ N a~ ~ ~ ~`I ~ U~ Itl _ ~ ~ Y') ~
3~ ~ l c~
_ ~ ~ ~ 07 ~ Z; :~ m ~ ~ æ m ~ , l l l l L~ l . ` ',: .' ' ,' ! , ',, = = -- -... , = _ o4, m~ ~ OD Co .
o u7 ,~ u~
o~
_ .
0~ O ~D ~ CO
~ , ~ O ~ ~
h _ ~ . ... _.. ___ ............. __ U~
~ u~ co a) o~
C`~ _ . _ ~ .~
E-l _~ ~ 3 0 ~D t~ O ID
::~ ~ O) ~ rl _~

:~ .-1 ~ c.') a~ tt) I 1` o o ~1 __ __ _ - . _ _ .

p~ ~; m m 3:~ ~ z ~
.
- ~- . . -- ¢~ ~ ~
- oo = = ' = ~

_ _~_ __ _ _ _ _ I~ , " , ! ,l ~ i ^

_ . . _ Ir~ I
~ ~ U7 ~ I

. o -1 l ~
~_ ~ ~ ~ ~ ~J U~
5~ ,1 ~ ~

~ ~ O ~ ~ O
,_ ~ ~ ~7 ~ ~ u~
~ ~ ,~ ~ I
~ _ . ........... ................................ .
_ ~ a~ I~ ~ (n u) ~1 ~ l _ ~ ~ 1 ~

_ _ _ . I
rd _~ ~ ~ ~ O ~ ~ OD
E~ ~ ~ C~ ~ ~ ~ In U~
t~ ~ ~
_ _ _.

,~
N ~ ~7 ~ 11'~
~.) ~ rl~1 ~I rt r~l _ _ ~ .. _ ...... _ _ ~ æ ~ z e~
. _ ~ ~ ~ ~

~ o n~ ~ 1~
~ ~ . ~

`: :

= u~ . . . ~ o r~l OD 0~ ~ O ~ ~1~ ~ ~ ~ l ~ ~ ~ I
_ : _ o I
~ n ; I - r~ ~a~ u~ I
_~ CD a~ o~ o o ~ ~ ~ ~ l ~ ~ ~ I
l I
_ _ o, I
~ ~ o~ ~~o ~o ~ ~ I
_ ,~ l ~ I
~ ~,) I .
U _ ~ . _ . _ ~ l I
a~ ~ C~ I
0 ~D ~ O O ~1 ~I C~ ~ ~ l ~ ~ ~ l ~ ~ ~ _ ~_ ~. l I
~d_ C`l 0~~ O~D C`l) ~ O~D
E~:~ 00 C~C~ OO ~1~1 ~ ,~ l ~ I

_ ~ Uo~ ~ l ~ -1 ~1~I . C~lN ~ l ¦ .
_ _ ~
r~ r~ I
Z ~ ~ _ Z;r ~ _ I
l l l l I
1(~
~ ~ ~
, .-'. 'I i ~ 38 ~
Among these mesogen groups, those of Nos.
1-18, 31-48f 61-78, 181-198 and 211-228 having cyano group or alkoxyl group are preferred. Those of Nos.
31-42 are especially preferred. Of these mesogen groups, those bonded to the polysiloxane-based backbone are preferred for high orientation performance. Those bonded to the cyclic siloxane backbone are most preferred.
Examples of the polymerizable mesogen groups usable for the linear-chain or cyclic liquid crystal oligomers composed of the recurring units (II) are shown in Tables 5-7.

~: ' . ' 1 = _ o I .
_ ~DC~l 1~ ~D l _ l 0~ It~ ~1 1~ I

~ ~ U~ U~ ~D I

3 ~ ~ C~ ~ I

O _ . I

~1 ~ O ~D ~ l 1 t~ I

_ I
P. _ _ ~ ~ ~ ~1 I

~ ~ ~ ~ ~ I
U~ _ _ . .

l I
E-~ Pl:: ~ ~ U-) ~D l l I

_ . _ _~ ,~ I~ ~ cr. I
q ~ ~ U~ I
C~ ~ C~ I

__ . _ _ I
T~ I ,.

_ _ _ -- ~10 --. _ = __ _ ~ _. .
O
l O ~D C`~00 5 0 _ I~ I~ OD0~ O~ O
~ C~ ~ ~ e~
_ O _.
l O~ U) ~ ~ O~
._ ~ aoco a~ ~o ~ ~ c~l ~ l C~
l __ . _ _ _ O
al ~ o u:~ ~ oo U~ I~ OD OD O~ O~
3: ~ ~ ~ ~ ~ ~
_ ~d 1~') 3 ~ ~ al a~ ~n ~ ~ ~ ~ C~ ~ ~

~D _ . ~ ~

E-~ ~'~ ~ ~
~: ~ ,~ ,~ co a~ o~
O ~ ~ C`3 C~ ~ ~

_ __ _ . _ _ ~ U') ~J
3: ~D ~` I~ OD CD O~
t~ ~ C~ ~ C~ C~
__ ~ ~ ~ m ~L L' I

= --- ~=- --ol _ O ~1 ~1 ~1 O ~D
l ~ -N O ,_1 /~ ~ a~ U'l 5 ~1 ~1 ~ 7 c~

0~ .. ~_..... _ - .. __ N d` O U~ C~l ~J
~-I _ ~1 ~1 C.'l ~'1 ~ ~1 td _ ~.

2 O O ~1 ~ C~ ~

.CI _ ~
E-- N ~ ~t O
:r~ o o ~ t~l ~
Cl~ ~ ~ ~ rr~ ~
_ _ _ _ ~ O O ~ ~1 ~ ~
_ _ ~ m X ~ ::a V

Among these polymerizable mesogen groups, those of Nos. 247-252, 259-264, 271~276, 319-324 and 331-336 ha~ing methacrylate group are preferred, and those of Nos. 259-264 are especially preferred. Of these mesogen groups, those bonded to the linear-chain or cyclic polysiloxane-based backbond are preferred as they give good properties to the subject oligomers or polymers, and those bonded to the cyclic polysiloxane backbone are especially preferred.
For the synthesis of these liquid crystal polymers or liquid crystal oligomers, the methods disclosed in JP-B-63-47759 and JP-A-4-16916 can be employed. More specifically, there can be used a method in which said side chain mesogen group is added to the polysiloxane backbone, or a method in which an azrylic acid ester or methacrylic acid ester ha~ing a mesogen group through a flexible spacer is polymerized. In case of adding mesogen group to the polysiloxane backbone, the reacting materlal having the same structure as the 20 side chain mesogen group of the rscurring units (I~, (II) and (IX) and having ~-alkenyloxy group producing an alkyleneoxy group (spacer) and having unsaturated double bond at the terminal is reacted with polysiloxane in the presence of a platinum catalyst.
In the case of a liquid crystal oligomer composed of the recurring units (I) and ~II), it is possible to control the bonding ratio of thP two types of mesogen groups, i.eO nonpolymerizable mesogen groups and polymerizable mesogen groups, by adjusting the feed rate of the reacting material relative to said mesogen groups in the reaction. Similarly, for those oligomers in which the backbone is an acrylic acid ester or an a-alkyl-acrylic acid ester, the :ratio of khe polymer-izable mesogen groups to the nonpolymerizable mesogen groups can be controlled by adju,sting the monomer feed rate when two types of monomers having the corresponding mesogen groups are copolymerized.
The liquid crystal oligomer obtained in the manner described above is preferably one which shows the nematic or smectic phase. ~he one which shows the smectic phase is preferred because of higher optical anisotropy.
The crystal phase or glass phase/liquid crystal phase transition tempe~ature of these liquid crystal oligomers is not specified in this invention; it may be below room temperature.
For making a film of a liquid crystal oligomer, liquid crystal oligomer composition or liquid crystal polymer which is oriented in a specific direction against the normal line of the film, a method is generally employed in which a film is formed on a substrate subjected to an alignment treatment and then the liquid crystal oligomer, oligomer composition or polymer is oriented by a heat treatment. The conditions of the orientation treatment of the substrate and the heat trea~ment for orientation varies depending on the . ....

- 4~ -direction of orientation, 50 that they axe properly selected case by case.
The method for making a film of a liquid crystal oligomer, liquid crystal oligomer composition or liquid crystal polymer is also not speci~ied in this invention. For instance, a method may be mentioned in which a liquid crystal oligomer, liquid crystal oligomer composition or liquid crystal polymer is coated on a substrate in a state of solution or in a state of isotropic phase. Coating in a state of solution is preferred. Coating may be accomplished by ordinary methods such as roll coating, gravure coating, bar coating, spin coating, spray coating, printing, dip coatin~, etc. The obtained liquid crystal oligomer or polymer film may be used in the form as it is, but i~ i5 preferably lami~a~ed on a substrate for commercial use.
The thickness of said liquid crystal oligomer or polymer film is preferably 0.1 to 20 ~m, more preferably 0.5 to 15 ~m, even more preferably 1 to 12 ~m. When the film thickness is less than 0.1 ~m, the film material may fail to develop its normal optical properties, and when the film thickness exceeds 20 ~m, the film i~ hard to orient.
Por making a film of a liquid crystal olig~mer or liquid crystal oligomer composition having the optical axis substantially parallel to the nonmal line of the film according to this in~ention, a film of said oligomer or oligomer composition is formed on a hydro-c - ~5 -philic substrate and then the film is oriented.
Orientation can be accomplished by heat-treating said film of liquid crystal oligomer or oligomer composition at a temperature above the trans:ition temperature from S the crystal phase or glass phase to the liquid crystal phase (this transition temperatuxe may hereinafter be referred to a~ Tg) and below the transition temperature from the liquid phase to the isotropic phase (this transition temperature may hereinafter be referred to as 18 Ti). As for the heat treatment temperature (which may hereinafter be referred to as Tt), preferably Tg + 30C

5 Tt < Ti, and the heat treatment is preferably carried out at a temperature defined by Tg + 40C ~ Tt < Ti.
The time of heat treatment is not critical in this invention, but too short a heating time results in unsatisfactory homeotropic orientation, while too long a heating time is undesirable for economical reason, so that the heat treatment time is preferably 0.2 minutes to 20 hours, more preferably one minute to one hour. As 2U a result of said heat treatment, the mesogen groups in the liquid crystal oligomer are oriented substantially homeotropie to the film plane, and consequently the film has the optical axis in the direction noLmal to the film plane.
In the case of pol~merized liquid crystal oligomer film, the film is ori~nted so that it will have the optical axis substantially parallel to the normal line of the film plane or in a specific direction and ' .. ...

" ~ . . ' , . ,.1.,.' then the liquid crystal oligomer is polymerized.
Polymerization method is not defined, but since the oligomer must be polymerized while maintaining orientation, photopolymerization, radiation polymer-ization using ~-rays, etc., or thermal polymerization is preferably employed. A known pol~merization initiator can be used in photopolymerization or thermal polymer-ization. Of these polymerization methods, photopolymer~
ization and thermal polymerization are preferred for simplicity of the process. Photopolymerization is most preferred for high stability of orientation.
In case the thermal treatment temperature is below the liquid crystal phase/isotropic phase transi-tion temperature, a substrate having a hydrophilic surface can be favorably used for providing orientation substantially parallel to the normal line of the film.
As such substrate, there can be used a glass plate as a single body or a ~lass plate bonded to a liquid crystal cell. It is also possible to utilize a hydrophilic polymer containing hydroxy groups, carboxylate ions or sulfonate ions. A polymer substrate having a hydro-philic polymer layer at the ~urface can be also used.
9f the hydrophilic pol~mers, those ha~in~
hydroxyl groups include polyvinyl alcohol, polyethylene-vinyl alcohol copolymer~ and natural polysaccharidessuch as pullulan and dextrin obtained from microbial fermentation of malt syrup. Of these polymers, poly - 47 ~
vi.nyl alcohol is preferred in view of solubility and easiness of homeotropic orientation.
Examples of the polymers containing carboxylate ions include polyacrylic acid, sodium polyacrylate, polymethacrylic acid, sodium polyalginate, sodium salt of polycarboxymethyl cellulose and others.
of these polymers, sodium polyalginate, sodium salt of polycarboxymethyl cellulose and polyacrylic acid are preferred.
A typical example of the polymers containing sulfonate ions is polystyrenesulfonic acid. Of these hydrophilic polymers, polyvinyl alcohol, sodium polyalginate, sodium salt of polycarboxymethyl celluose, polyacrylic acid, pullulan and polystyrene sulfonic acid are preferred. Polyvinyl alcohol and sodium poly-alginate are especially preferred.
For orienting the nonpolymerizable side chain type liquid crystal oligomer or side chain type liquid crystal polymer in the direction substantially parallel to the normal line of the film, either a hydrophilic or a hydrophobic substrate can be used, and in this case, heat treatment is carried out at a ~emperature above the liquid crystal phase/isotropic phase transition tempera-ture of the liquid crystal oligomer or liquid cryskal polymer. The hydrophilic substrate used here is preferably one in which the contact angle with water is 60 or less, preferably 50 or less. In the case of hydrophobic substrate, ~he contact angle with wa~er is . .

.

.

85 or greater, preferably 90 or greater. Use of a hydrophilic substrate is preferred because of easy homeotropic alignment. The hydrophilic polymers usable here include the above~mentioned polymers having hydroxyl groups, carboxylate ions or sulfonate ions.
The hydrophobic polymers usable for making said substrate include fluorine polymers such as polytetra-fluoroethylene and polyvinylidene fluoride, polymers such as polycarbonate, polysulfone, polyarylate, polyethersulfone, cellulose triacetate, cellulose diacetate and polyethylene terephthalate, and hydrophilic polymers sueh as polyvinyl alcohol and saponified ethylene-vinyl acetate copolymer, which polymers have been subjected to a treatment for making them hydrophobic. The treatments useful for making said polymers hydrophobic include coating with a fluorine polymer or a surfactant such as lecithin, and reaction of said polymers with a silane coupling agent or titanium coupling agent.
The temperature of thermal treatment of the liquid crystal oligomer film or liquid crystal polymer layer formed on a substrate is preferably above the llquid crystal phase/isotropic phase transition temper-ature of the liquid crystal oligomer or liquid crystal polymer used and below the glass transition temperature of the substrate. When the thermal treatment temper-ature is higher than the glass transition temperature of the substrate used, there arise the problems in the production process, such as deformation o~ the sub-strate. The optimal temperature range for the heat treatment can be properly selected by taking into consideration transition tempexature of the polymer liquid crystal used and glass transition temperature of the substrate used.
The alignment treatment of the substrate used for orienting the mesogen groups in such a direction as to let the film have the optical axis inclined 10-80, in terms of angle of elevation, from the film plane in the present invent.ion varies depending on the phase structure of the liquid crystal used.
For instance, in case of using a liquid crystal material showing the nematic or smectic A phase, there can be employed a method using an oblique evapora-tion film of an .inorganic material on the substrate, or a method in which after formation of an oblique evapora-tion film of an inorganic material, a surface treatment is carried out with a surfactant suoh as lecithin or a known homeotropic alignment agent such as silane coupl-ing agent or titanium coupling agen~. In carxying out oblique evaporation of an inorganic material, said inorganic material is preferably applied at a small angle against the substrate so that the oblique evapora-tion will be performed uniformly. Specifically, theinorganic material is preferably applied at an angle of 45 less, more preferably 30 or less, in terms of angle of eleYation fxom the substrate surface.

, .

. . :. . . , : ~ ~ :. , J

~ 50 ~
The direction of inclination of the optical axis of the liquid crystal polymer or liquid crystal oligomer film obtained by using said oblique evaporation film relates to the direction of evaporation, so that it is possible to ~et the optical axis in a desired direc-tion in the film plane by fixing the direction of evapo-ration. However, the tilt angle of th~ optical axis and the evaporation angle do not usually agree with each other and vary depending on the alignment agent and liquid crystal material used.
The inorganic material used for evaporation in the present invention is preferably one which makes prismatic growth during evaporation. Preferred examples of such inorganic material are SiO, SiO2, SiO~, MgF2, Pt, 15 ZnO, MoO3/ ~o3, Ta20s, SnOz, CeO2, LiNbO3, LiTaO3, ZrO2, Bi203, TiZrO4 and MgO~ (l<x~2). Of these compounds, SiO, SiO2~ SiO~ M~O, MgOx, MqF2, Pt and ZnO are preferred.
SiO, SiO2 and SiO~ are especially preferred.
The method for oblique evaporation is not specified in this inventionO Such evaporation may be accomplished by making use Qf re~istance heating or electron-beam heating or by sputtering. Evaporation by electron~beam heating or sputtering is preferred for depositing a high-melting point inorganic material. The degree of vacul~m for evapoxation is not critical. The upper limit of pressure that can b~ applied is decided from the viewpoint of uniformity of the deposit~d ilm, and the lower limit of pressure is decided from the :~
. . .

~ o~

viewpoint of productivity. Specifically, said evapora~
tion is usually carried out under a vacuum of l x 10-3 to 1 x 10-7 Terr, preferably 5 x 10-4 to 5 x 10-6 Terr.
The deposition rate of inorganic material is also not critical in this invention, but it is to be noted that a low deposition rate leads tv poor produc-tivity while a hiqh deposition rate may deteriorate uniformity of the deposited film. In view of this, the deposition rate is preferably set at 0.01 to 10 nm/sec, more preferably 0.1 to 5 nm/sec.
Concerning thickness of the deposited film of inorganic material, the fact is ~o be noted that a small film thickness tends to deterioxate alignment while a large film thickness is prejudicial to productivity. In view of this, the deposited film thickne~s should be 0.01 to 1,000 ~m~ preferably 0.05 to 100 ~m, more preferably 0.1 to 5 ~m.
In case of using a liquid crystal material showing the smectic C phase, it is possible to obtain a liquid crystal polymer or liquid crystal oligomer film having the optical axis with an inelination of 10-80 by forming a film of said liquid crystal material on a vertically oriented substrate and then orienting the formed film. In this case, oblique evaporation, rubbing or application of a magnetic or electric f ield may be employed f or aligning the tilt dir~ction of mesogen groups.
Homeotropic orientation treatment usually - 52 ~
comprises making the substrate surface hydrophobic with a surfactant such as lecithin or a silane or titanium coupling agent, but in the case of the liquid crystal polymer or liquid crystal oligomer of the present invention, good homeotropic orientation can be obtained by making the substrate surface hydrophilic aft~r oblique evaporation.
Known surface improving methods and techniques can be utilized for making the deposited film surface hydrophilic, for example, a method in which a hydro-philic polymer containing hydroxyl groups, carboxylate ions or sulfonate ions is coated on the substrate, or a method in which the substrate is subjected to a plasma treatment, corona discharge treatment or ozone treatment with u~traviolet rays, in an oxygen or water vapor atmosphere. As the polymer for making the film surface hydrophilic, there can be used said polymers having hydroxyl groups and the pol~mers having carboxylic acids. When a hydxophilic polymer is coated on the deposited film formed by oblique evaporation, the coating thickness of said hydrophilic polymer should be 1 nm to 10 ~m, preferably 5 nm to 2 ~m, more preferably 5 nm to 1 ~m, or maximizing the Qffect of said hydro-philic polymer. Any type of solvent can be used in the above treatments as far as it is capable of dissolving the hydrophilic polymers, but usually ~ater is preferably used as solvent.
In the present invention, heat treatment is employed for orienting the film in a specific direction, and it is pos~ible to change the film characteristics such as orientation, viscosity and optimal heat treatment temperature in the more favorable ranges by mixing a low molecular weight compound capable of lowering the liquid crystal phase/isotropic phase transition temperature of the liquid crystal oligomer.
~ he low-molecular weight compound to be mixed in the liquid crystal oligomer in the present invention is at least one compound selected from the group consisting of the compounds of the formulae (VI), (VII) and (VIII) shown and described above.
Referring to the low-molecular weight com-pounds represented by the formula (VI), R3 in said formula repr~sents an alkyl group having 3-30 carbon atoms or an alkoxy group having 3-30 carbon atoms, such as propyl, butyl, hexyl, octyl, dodecyl, octadecyl~
docosyl, eicosyl, propoxy, butoxy, hexyloxy, octyloxy, dodecylo~y, oc~adecyloxy, docosanoxy and eicosyloxy.
R4 represents halogen, cyano group, meth-acryloyl group, acryloyl group, an alkyl group having 1-20 carbon atoms or an alkoxy group ha~ing 1-20 carbon atoms. The alkyl groups and alkoxy groups repr~sented by R4 include methyl, ethyl, propyl, butyl, hexyl, octyl, dodecyl, octadecyl, methoxy, ethoxy, propoxy, butoxy, hexylo~y, octyloxy, dodecyloxy and octadecyloxy.
The low-molecular weight compounds represented by theformula (VI~ include, as their preferred examples~

- 54 ~
the compounds of the following formula (XII~:

R3 ~ - R4 (XII) Cyanobiphenyl-based compounds are especially preferred.
Typical examples of such compouncls are 4-cyano-4'-hexylbiphenyl, 4-cyano-4'-octylbiphenyl, 4-cyano-4'-octyloxybiphenyl and the like.
Referring to the low-molecular weight compounds represented by the $ormula (VII) R5 and R6 represent independently hydrogen, alkyl group having 1 20 carbon atom~ or alkoxy group having 1-20 carbon atoms. The alkyl groups and alkoxy group~ represented by R5 and R6 include methyl t ethyl, propyl, butyl, hexyl, octyl, dodecyl, oc$adecyl, methoxy, ethoxy, propoxyl butoxy, hexyloxy, ockyloxy, dodecyloxy and octadecyloxy.
Examples of the low-molecular weight compounds represented by the formula (VII) include 4-methylbenzo-phenone, 4-ethylbenzophenone, 4-bukylbenzophenone, 4-octylbenzophenone,4-methoxy~enæophenone, 4-ethoxy-benzophenone, 4-butoxybenzophenone, 4-octyloxybenzo-phenone, 4~4'-dimethoxybenzophenone, 4,4'-diathoxybenzo-phenone, 4,4'-dibutoxybenzophenone and 4,4'-dioctyloxy-benzophenone. Of the~e compounds, 4-methoxybenzophenone is preferred.

Referring to the low-~olecular weight com-,, :.I..,i ,., .. ,, :.,- 55 -pounds represented by the formula (VIII ), R7 is hydrogen or methyl group, and R8 is hydrocarbon group having 1-30 carbon atoms. The hydrocarbon groups represented by ~8 include methyl, ethyl, propyl, butyl, hexyl, octyl, dodecyl, octadecyl, docosyl and eicosyl.
Examples of the low-molecular weight compounds represented by the formula (VIII) include methyl acryl-ate, ethyl acrylate, butyl acrylate, octyl acrylate, dodecyl acrylate, octadecyl acrylate, methyl meth acrylate, ethyl methacrylate, butyl acrylate, octyl methacrylate, dodecyl methacrylate and octadecyl meth-acrylate. Of these compounds, octadecyl methacrylate is preferred.
In the present invention, a low~molecular weight compound is blended in an amount of 0.1 to 40 parts by weight, preferably 0.5 to 25 parts by weight, more preferably 1 to 15 parts by weight, to 100 parts by weigh~ of liquid crystal oligomer. When the amount of said low-molecular weight compound is less than 0.1 part by weight based on said oligomer, the effect of addition of said compound is nil, and when the amount exceeds 40 parts by weight, the compound may gi~e adverse effect to the properties of the produced film.
The blending method is not specified. The compound may be blended in a state of solution, isotropic phase~ etc., but blending in a state of solution is preferred for facilitation of film forming process.

. . : ' 3 The present invention is also embodied as a substrate used for a laminate of an oriented optically anisotropic film and a transparent or semitranr~parent substrate on which alignment treatment has been carried out. As the subr~trate of the homeotropically oriented optically anisotropic film, there can be used the above-mentioned glass plate and films of polymers having hydroxyl groups, carboxylic acid ions or sulfonic acid ions. It is also possible to use a transparent or semi-transparent polymer film having its surface constitutedby a hydrophilic polymer such as mentioned above. The form of the hydrophilic substrate used is thin plate-like or film-like when the substrate is used for a liquid crystal display device. Film i~ preferred for polymer material. In the case of an optically anisotropic film having the optical axis at an angle of elevation of 10-80~ from the film plane, a glass plate or a transparent or semitransparent polymer film can be used as substrate, and the film is subjected to said orien~ation trea~ment. The form of the sub~trate used is thin plate-like or film~like. Film is preferred for polymer material.
In the laminate of an optically anisotropic film and a hydrophilic substrate according to the present invention, the hydrophilic substrate is effective for aligning the optical axis of the film substantially parallel to the direction normal to the film plane. ~owev~r, since the rubbed po]yvinyl alcohol - 57 ~
film acts as a homogeneous alig~ment film as mentic)ned above, rubbing is undesirable for the hydrophilic polymer layer as such treatment gives adverse effect to alignment of the optical axis.
As the material of the transparent or semi-transparent polymer film whose s~lrface is coated with a hydrophilic polymer or of the polymer film serving as a substrate used for oblique evaporation in the present invention, there can be used polycarbonate, polysulfone, polyarylate, polyether sulfone, cellulose diacetate, cellulose triacetate, polystyrene/ ethylene-vinyl alcohol copolymer, polyethylene terephthalate, poly-ethylene naphthalate and the like. Of these polymers, polycarbonate, polysulfone, cellulose triacetate polyethylene terephthalate and polystyrene are preferred.
For aligning the optical axis substantially parallel to the direction normal to ~he film in the laminate of an optically anisotropic film and a hydrophilic sub~trate according to the present inven-tion, said laminate is subjected to a heat treatment under the same conditions as in the case of the opti-cally anisotropic film. Here, it is recommended to use a polymer which remains unchanged in optical properties or shape in the working temperature range. In the cass of the thermoplastic engineering polymers with high glass transition temperature or the polymers blended with a plasticizer/ those having a high flow temperature are preferably used. Glass transition temperature of the polymer used is not specified, but it i~ preferably 10~C or above, more preferably 110C or above.
Preferred examples of the pol~mers which meet the above conditions are cellulose triacetate, poly-carbonate, polysulfone, polyether sulfone and poly-ethylene terephthalate. q'he first four are especially preferred.
Then, in case of using a polymerizable liquid crystal oligomer, it is polymerized in the same way as the liquid crystal oligomer polymer film, ~nd orienta-tion is fixed.
The laminate of the present invention can take another embodiment wherein the laminate comprises an aligned polymerized liquid crystal oligomex film and a polymer substrate subjected to a hard coat treatment.
As the polymer substrate, there can be used substrates made from polycarbonates, polysulfones, polyallylates, polyether sulfones, cellulose diacetate, cellulose triacetate, polystyrenes, ethylene-vinyl alcohol copolymers, polyethylene terephthalates, polyethylene naphthalates, etc. Among these polymers, polycarbonates, polysulfones, polyethylene terephtha-lates and polystyrenes are preferable.
The term "hard coat treatment~ means a treatment of a surface of the polymer substrate with a hard coat agent;, e.g. coating, or formation of a hard coat layer ther~on so as to make the substrate surface harder than the untreated strate in terms of a pencil haxdness.
As the hard coat agent, there can be used conventional hard coat agents. The formation of the hard coat layer can be carried out by conventional processes. It is preferable to use a hard coat agent or a hard coating process so as to give a hard coat layer having a thickness of 2 ~m or more or a surface hardness of HB or more in terms of the pencil hardness~ prefer-ably a thickness of 5 ~m or moret or the surface hard-ness of H or more.
As the hard coat agent, there can be used conventionally used polyurethane series, acryl oligomer series, acryl-silicone series, organopolysiloxane series, and inorganic compounds, which are disclosed in Plastic Coating Technical Handbook (pages 183 - 191, puhlish~d by Sangyo Gijutsu 5ervice Cenker Ltd.). From the viewpoint of alignment of liquid crystal oligomers, the use of unsaturated polyesters of photocurable resin type, urethane-acrylate resins epoxy-acrylate resin~, polyester-acrylic resins, organopolysilocanes and inorganic compounds is preferable among these examples.
Further, from the viewpoint of film-forming property, the use of photocurable type resins, acryl oligomers and organosiloxanes is more preferable as the hard coat agent.
In the case of f orming a liquid crystal oligomer layer on the hard coat treated polymer sub-strate, there can be carried out a conventional surface modifying technique such as a plasma treatment, a corona treatment, ultraviolet radiation, a saponification treatment upon the hard coat layer so as to enhance surface tension of the polymer film, resultin~ in improving the uniformity of fi:Lm formed.
The hard coated pol~ner substrate can be prepared by film forming a hard coat agent or a surface of a transparent or semi-transparent polymer film used as a substrate. As the polymer for the polymer sub-strate, there can be used polycarbonates, polysulfones, polyallylates, polyether sulfones, cellulose diacetate, cellulose triacetate, polystyrenes, ethylene-vinyl acetate copolymers, polyethylene terephthalates, polyethylene naphthalates, etc.
~ s the film forming process of hard coat agent, there can be used con~entional coating methods such as a roll coating method, a dipping method, a gravure coating method, a bar coating method, a spin coating method, a spray coating method, and a print coating method using dissolved or disper~ed state of the hard coat agent in a solvent; and conventional evapora~
tion methods such as a sputtering method in vacuum, an electron beam heating evaporation method, a resistance heating method, etc. After film fo~mation, curing of the xe~ulting film can be carried out by ultraviolet irradiation, heat treatment, or the like depending on the kind of hard coat agent u~ed.

-- 61 ~ L '~
When the film is formed hy the evaporation method, care should be taken as to the direction of evaporation. The use of oblique evaporation is not preferable due to giving undesirable influences on the optical axis of the aligned liquid crystal oligomer.
Now, a process of making a laminate of substrate subjected to an alignment treatment and an optically anisotropic film according to the present invention is described by taking up the case where a substrate formed by applying a hydrophilic polymer on the surface of a polymer film and a liquid crystal oligomer are used. First, a film of a hydrophilic polymer is formed on the surface of a transparent or semitransparent polymer film, such as a film of polycarbonate, polysulfone, polyarylate, polyether sulfone, cellulose diacetate, cellulose ~riacetate, polyethylene terephthalate, polyethylene naphthalate or the like.
The method of forming a film of a hydrophilic polymer is not specified in this inven~ion. For example, ths film can be formed by dissolvinq said polymer in a solvQnt which can dissolve said polymer but scarcely causes dissolution or swelling o~ the sub-strate, and the solution is coated on the substrate by a known coating method such as gravure coating, bar coating, spin coating, spray coating, printing, dipping, etc., or the pol~mer is melted and coated on the substra~e by a known coa~ing method such as roll ,, . .: ., :.,,. ", . ..

coating, gravure coating, bar coating, spray coatin~, dipping, etc.
In view of easiness of operation, it is recommended to form the film from a polymer solution by using such coating method as roll coating, gra~ure coating, bar coating, spin coating, spray coating or dipping.
Some types of polymex film, such as the films of polycarbonate, polystyrene, polyarylate and polyether sulfone, are small in surfac~ tension and may rzpel the hydrophilic polymer solution, so that in case of u~ing such films, they may be subjected to a known surface treatment, such as plasma treatment, corona discharge, ultraviolet irradiation, etc., for increasing the surface tension of the film before forming thereon a film of a hydrophilic polymer.
The thickness of the transparent or semitrans-, parent polymer film used in ~his inven~ion is no~
critical, but it is preferably 1 to 500 ~m, more prefer-ably 10 to 300 ~m, still more preferably 40 to 200 ~m.
The thickness of the hydrophilic polymer film is also not criticalt but it is usually 0.1 to 500 ~m, preferably 0.5 to 100 ~m, more preferably 1 to 50 ~m.
As for the solvent, any solvent capable of dissolving the hydrophilic polymer can be used, but it is r~3com-mended to use water for economical reason.
Then, a film of a liquid crystal oligomer is formed on the hydrophilic pol~mer film. The film .. : .,. .: - . . .. : .

- 63 ~ 9... ~ d forming method is not specified. For example, the film can be formed by dissolving a liquid crystal oligomer in a solvent which can dissolve said liquid crystal oligomer but scarcely causes dissolution or swelling of the substrate or hydrophilic polymer, and coating the solution on the substrate by a known coating method such as roll coa~ing, gravure coating, bar coating, spin coating, spray coating, printing, dipping, etc., or by heating said liquid crystal oligomer to a temperature above the solid phase/li~uid crystal phase transition temperature of said liquid crystal oligomer to reduce its viscosity, and then coating it on the substrate by a suitable coating method such as roll coating, gravure coating, bar coating, spray coating, dipping, etc. In view of easiness of operation, it is recommended to form the film from a liquid crystal oligomer solution by using such coating method as roll coating, gravure coating, bar coating, spin coating/ spray coating or dipping.
The thickness of the thus formed liquid crystal oligomer layer is preferably 0.1 to 20 ~m, more preferably 0.5 to 10 ~mt eYen more preferably 1 to 7 ~m.
When the layer thickness i9 less than 0.1 ~m, the layer may fail to deYelop the optical properties of the liquid crystal oligomer to a satisfactory degree, and when the layer thickn~ss is great~r than 20 ~m, orientation becomes hard ~o conduc~.
As described above, for obtaining ~ high - 6~ -degrce of homeotropic orientation of the liquid crystal oligomer, the liquid crystal oligomer/polymer laminated film is heat-treat~d at the same temperature for the same period of time as in the case of the aforementioned liquid crystal oligomer polymer film. However, in the case of a substrate having certain glass transition temperature or a subs~rate incorporated with certain additives, there tends to take place deformation of the substrate or hydrophilic polymer layer formed on a substrate when the working temperature is above the flow temperature of the substrate, so that the upper limit of working temperature is preferably set below the glass transition temperature or flow temperature of the substrate. By this treatment, the liquid ~rystal oligomer film on the polymer substrate is substantially vertically oriented. The heating rate and cooling rate in the heat treatment are not critical.
In the case of a polymerizable liguid crystal oligomer, it is polymerized after orientation in the same way as in the case of liquid crystal oligomer polymer.
For producing a transparent or semitransparent polymer film of this invention, there can be employed a suitable molding method such as solvent casting, extrusion molding or press molding.
A laminate of a liquid crystal oligomer polymer and a substrate can be similarly obtained when using a glass plate or a hydrophilic polymer film as - . : .

. - :.

substrate.
In the oriented liquid crystal oligomer polymer film or the laminate of an oriented liquid crystal oligomer polymer film and a hydrophilic sub-~trate according to the present invention, the opticala~is is substantially parallel to the normal line of the film, so that by using a plural number of the uniaxially oriented retardation films having the optical axis in the film plane, said films also having positive ani-sotropy of refractive index and made of a thermoplasticpolymer, it is possible to make a composite retardation plate or composite retardation film. Also, in the laminate of an optically anisotropic film and substrate subjected to an alignment treatment according to the present invention, the optical axis is incline~ 10-80, in terms of angle of elevation, from the film plane, so that by using the uniaxially oriented retardation films having the uptical ax7s in the film plane, which films have positive anisotropy of refractive index and are made of a thermoplaskic polymer, it is possible to make a composite retarda~ion plate or composite retardation film. ~ereinafter, the composite retardation plate and composite retardation film are referred to representa~
tively as composite retardation plate.
It is known in this art that the viewing width of composite retardation plate relates to the maximum value [nx) of the in-plane refractive index of the composite retardation plate, the minimum value (ny) of ~. . . .. .:.;: ~ . -the in-plane refractive index of the composite retarda-tion plate, and the refraction index (nz) in the thick-ness direction of the composite retardation plate.
The anisotropy of refraction index can be obtained as an arithmetic mean of refractive indexes of individual constituting material plates and films.
Since the composite retardation plate shows retardation, it is practical to estimate the anisotropy of refractive index from the angular dependence of retardation.
When the anisotropy of refractive index is evaluated by the ratio R( a ~ /R~0), wherein R(0) is retardation in the vertical direction to the composite retardation plate; and R(9) is the retardation inclined at an angle of ~ degree, a good viewing angle property is shown in the range of:
1.10 ~ R(40)/R(0) ~ 0.90 corresponding to:

nx ~ nz > n~
As examples of the thermoplastic polymers having positive refractive.index anisotropy usable for the composite retardation plate of the present inven~
tion, there can be mentioned, for instance, poly-carbonate, polysulfone, polyarylate, polyether sulfone, cellulose diacetate, cellulose triacetate, polyvinyl alcohol, polyethylene-vinyl alcohol copcl~mer and polye~hylene terephthalate. ~ film of such thermo-plastic polymer is uniaxially oriented and used as a retardation film.

: ~

.. .. . . ..

The laminate of liquid crystal oligomer/
hydrophilic substrate and the uniaxially oriented retardation film may be bonded to each other with a binder or other means to form a laminate, or they may be used separately from each other.
For producing a film (base film) used as base of a retardation film made of a thermoplastic polymer such as mentioned ab~ve, a suitable molding method such as solvent casting, extrusion molding or press molding can be employed. For stretchin~ the base ilm for making a uniaxially oriented retardation film having the optical axis in the film plane, there can be employed the known stretching methods such as tentering, roll stretching and roll compression stretching. For obtaining a homogeneous retardation film, preferably a film formed by solvent casting is stretched by tentering.
In the liquid crystal display de~ice of the present in~ention, the position of the optically anisotropic film, the laminate o~ an optically anisotropic film and a hydrophilic substrate, or the composite retardation plate containin~ an optically anisotropic film, is not specified; they may be placed at any position between a pair of polarizing plates of a liquid crystal display. For instance, they may be disposed between a polarizing plate and a liquid crystal cell for display, between a polarizing plate and a polarizing plate protective film, between a retardation film and a polarizing plate, between a retardation film and a liquid crystal cell for display. Further, an aligned polymerized liquid crystal oligomer film can be positioned at either a near sider or a far side of the liquid crystal cell. In order to obtain a liquid crystal display device having a wider viewing angle, it is preferable to position the aligned polymerized liquid cxystal oligomer film between a uniaxially oriented retardation film and a polarizing ~ilm.
The present invention is further illustrated below with reference to the examples thereof, which e~amples however are merely intended to be illustrative and not to be construed as limiting the scope o the invention.
The glass transition point and liquid crystal phase/isotropic phase transition temperature of the ob$ained liquid crystal oligomers were determined by observa~ion with a polarization microscope and a dif-ferential scanning calorimeter (DSC). That is, each liquid crystal ollgomer was scanned at a rate of 10Ctmin, and the transition temperature was determined from the d~ta of the second and ensuing runs of scanning. As for Tg, the peak of primary differential of the endothermic curve during rise of temperature was regarded as Tgl and as to Ti, the endothermic peak supposed to be due to liquid phase/isotropic phase transition was regarded as Ti.
Fo:r confirmation of the fact that the obtained . - , - ~ , ::, : : : :

laminate of a liquid crystal oligomer polymer film and a substrate had the optical axis substantially in the direction normal to the film plane, it was observed whether ex~inction would take place almost perfectly when said l~minated film was p:Laced horizontally under crossed nicols in case the substrate had no birefrin-gence, and then it was further observed whether retardation would enlarge with increase of inclination of the film about an optionally selected axis.
For evaluating the lamina~ed composite retardation plate or film of the present invention, first in-plane double refraction of said plate or film was examined. Said laminated film was placed in a polarization microscope equipped with a tilting stage, and retardation (R(0)) was determined according to S~narmont's double refraction measuring method using Sénarmont compensator.
Then double refraction in the thickness direction was evaluated with reference to retardation (R(~)) determined with the optical axis in thP homo-geneous plane being inclined by an angle of Q.
As for the ~iewing n~le of -the laminated composite retardation plate or film, the angle ~ when R(~) = l.lO x R(0) was defined as the viewing angle of said plate or film.
The present invention is illustrated by way of the following Examples, in which all percents are by weight unless otherwise specified.

~ 3;..

Example 1 A 7~ aqueous solution of polyvinyl alcohol (Poval 117, produced by Ruraray Co., Ltd.) was coated on an 80 ~m thick cellulose triacetate film a~d dried in hot air of 100C. The resultantly obtained polyvinyl alcohol film was 3 ~m thick.
A 1 : 1 mixture of 4-(allyloxy)-benzoic acid-4'-cyanophenyl ester and 4-(allyloxy)-benzoic acid-(4'-methacryloyloxyphenyl) ester was reacted with pentamethylcyclopentasiloxane in the same way as described in USP 4,410,570 to obtain a liquid crystal oligomer comprising, as its main structural units, cyclic pentasiloxane oligomer having in its side chain nonpolymerizable mesogen groups and polymerizable mesogen groups in a ratio of about 1 : 1. Elemental analy~is of this liquid crystal oligomer showed C =
61.7 9 H = 5.3, and N = 2Ø The content of the cyclic pentasiloxane liquid crystal oligomer as determined in terms of gel permeation chromatographic areal percentage was 69%, and that of the unreacted monomer was 4.5%.
The addition rate of side chain mesogen as determined from integration of the peak on H-NMR spectrum was about 80%.
Tg of the obtained liquid crystal oligomer was 18.7C7 and Ti was 117.5C. This liquid crystal oligomer was dissolved in methylene chloride to a con-cPntration of 5 wt%, and then Irgacure 907 (produced by Ciba-Geigy AG) was mixed as photopol~merization ini-tiator in an amount of 2 wt% based on the liquid crystal oligomer. This liquid crystal oligomer solution was applied on a polyvinyl alcohol-coated cellulose tri-acetate film by using an applicator with a gap width of - 5 40 ~m, followed by during at room temperature. The resultantly formed liquid crystal oligomer film was cloudy.
The thus obtained liquid crystal oligomer/
polyvinyl alcohol/cellulose triacetate laminated film was heated on a 95C hot plate for 5 minutes and then cooled. Then this laminated film was irradiated with light from a high pressure mercury lamp at a light intensity of 500 mW/cm2 on the irradiated surface.
The obtained liquid crystal oligomer polymer/
polymeric compound laminated film became optically extinct under crossed nicols and showed retardation of 5.3 nm which was supposed to be ascribable to cellulose triacetate, but retardation enlarged when the laminated film was inclined from the homogeneous plane. The relation between inclination angle and retardation is shown in Fig. 1. In view of the fact that retardation enlarges with increase of inclination angle, it is seen that the liquid crystal oligomer polymer is oriented vertically. The thickness of this liquid crystal oli~omer polymer layer measured by using a needle surface prof.iler ~s a thickness meter (Alpha Step AS-200 mfd. by Tencor Co.) was 2.3 ~m.
Then, in order to obtain a uniaxially oriented -~ - 72 retardation film having the optical axis in the film plane, said film also having positive anisotropy of refractive index and made of a thermoplastic polymer, an 80 ~m thi.ck polycarbonate base film was formed by S solvent casting, and this base film was stretched 1.2 times at 185C by longitudinal uniaxial stretching method. The obtained polycarbonate retardation film had a thickness of 66 ~m and a viewing angle of 39 with R(0) = 380 nm.
When this polycarbonate retardation film and a liquid crystal oligomer polymer/polymeric compound laminated film were laminated, the viewing angle became greater than 60~, and there was obtained a composite retardation film with a greater viewing angle than that of the polycarbonate retardation film alone. Further, when this composite retardation film is placed between the upper polarizing plate and the corresponding liquid crystal cell of an STN type liquid crystal display de~ice, black and white display is given, and the film shows excellent vie~ing angle characteristics.

Comparative Example 1 The procedure of Example 1 was carried out except that no heat treatment was conducted after coating of the liquid crystal oligomer to obtain a laminated film of a liquid crystal oligomer pol~mer and a polymeric substancs. The obtained laminated film was cloudy.

r, ..J 5 Observation of the laminated film under crossed nicols confirmed cloudiness of the film and showed that the liquid crystal oligomer polymer was not oriented vertically.

Example 2 The procedure of Example 1 was followed except that sodium alginate was used in place of polyvinyl alcohol to obtain a laminated Eilm of a liquid oligomer polymer film and a polymeric substance. This laminated film was transparent under crossed nicols and showed retardation of only 3 nm, but when the film was inclined from the homogeneous plane, retardation enlarged. It was 105 nm when the film was tilted 50. As retardation enlarged proportionally to the inclination, it was confirmed that th~ liquid crystal oligomer polymer layer was oriented vertically.
When the polycarbonate retardation film used in Example 1 and said laminated film were laminated, the viewing angle became greater than 60, ~nd there was obtained a composite retardation ilm with a greater viewing angle than that of the polycarbonate retardation film alone.
When this composite retardation film is plac d between the upper polarizing plate and the corresponding liquid crystal cell of an STN type liquid crystal display device, black and white display is gi~en and the film shows excellent viewing angle characteristics.

.. ~ - , .

.

Example 3 The procedure of Example 1 was followed except that the cellulose triacetate film was replaced by a polycarbonate retardation film (viewing angle: 39) with R(0) = 380 ~m prepared by the same method as used in Example 1 to obtain a laminated film of a liquid crystal oligomer polymer film and a polymexic substance.
This laminated film showed retardation of 382 nm, which was almost equal to retardation of the poly-carbonate retardation film alone. There took placelittle change of retardation even when the laminated film was tilted from the homogeneous plane, while the viewing angle was greater than 60, indicating a remarkable improvement of viewing angle as compared with that of the single retardation filmO
When this composite retardation film is placed between the upper polarizing plate and the corresponding liquid crystal cell of an STN t~pe liquid crystal display device, black and white display is given and the film shows excellent viewing angle characteristicsO

Example 4 The procedure of Example 1 was repeated except for use of a nonstretched polysulfone film in place of the cellulose triacetate film to obtain a laminated film of a liquid crystal polymer film and a polymeric substance. Retardation of this laminated film was 3 nm, about the same as retardation of the nonstretched l~` _l. i.`.. `

polysulfone film alone. Retardation enlarged when the laminated film was tilted from the homogeneous plane.
Retardation at inclination of 60 was 64 nm. As retardation enlarged with increase of film inclination, it was confirmed that the liquid crystal oligomer polymer layer was oriented vertically.
When the polycarbonate retardation ~ilm used in Example 1 and said laminated film were laminated, the viewing angle became greater than 60 and there was obtained a composite retardation film with a greater viewing angle that of the single polycarbonate retarda-tion film.
When this composite retardation film is placed between the upper polarizing plate and the corresponding liquid crystal cell of an STN type liquid crystal display device, black and white display is given and the film shows excellent viewing angle characteristics.

Example 5 The procedure of Example 1 was followed except that the cellulose triace~a~e film was replaced by a glass plate and that no polyvinyl alcohol was used to obkain a laminated film of a liquid crystal oligomer polymer film and glass. The obtained laminated film was transparent under crossed nicols and showed zero retardation. But retardation appeared and enlarged as the laminated film was ~ilted from the homogeneous a plane. Retardation at 50 inclination was 99 nm. In view of the f~ct that retardation enlarged with increase of tilt angle of the film, it was confirmed that the liquid crystal polymer layer was oriented vertically.
The thickness of the liquid crystal oligomer polymer layer was 2.0 ~m. When said laminated film and a polycarbonate retardation film were laminated, th~
viewing angle became greater than 60 and there was obtained a composite retardation film with a greater viewing angle th~n that of the single polycarbonate retardation film.
When this composite retardation film is placed between the upper polarizing plate and the corresponding liquid crystal cell of an STN type liquid crystal display device, black and white display is ~iven and the film shows excellent viewing angle charactexistics.

Example 6 A 7~ a~ueous solution of polyvinyl alcohol (Poval 117, produced ~y Kuraray Co., Ltd.) was coated on an 80 ~m thick cellulose triacetate film and dried in hot air of 100C. The formed polyvinyl alcohol film was 2 ~m thick.
A cyclic pentasiloxane liquid crystal oligomer obtained in Example 1 was dissolved in methylene chlo-ride to a concentration of 10 wt%. In ~his solution were mixed 4-cyano-4~-hexylbiphenyl and, as pho~o-polymerization initiator, Irgacure 907 (produced by Ciba-Geigy A~) in amounts of 3 wt% and 2 wt%, respec-,, - . , , . ~ . ~, - , . . : .. ., ~,-, .. - . . ..

:

-- 7 7 ~
tively, based on the liquid crystal oligomer. The thus prepared liquid crystal oligomer composition solution was coated on a polyvinyl alcohol-coated cellulose tri-acetate film by using a bar coater and dried at room temperat~re. Th0 resultantly formed liquid crystal oligomer composition film was cloudy.
The thus obtained three-layer (liquid crystal oligomer composition/polyvinyl alcohol/cellulose tri-acetate) laminated film wa~ heated in a 70C thermostat for 5 minutes and then irradiated with light from a high pressure mercury lamp at alight intensity of 500 mW/cm2 on the irradiated surface.
The obtained laminated film of liquid crystal oligomer polymer composition and polymeric substance hecame extinct under crossed nirols and showed retarda-tion of 5.3 nm which was supposed to be attributable to cellulose triacetate, but retardation enlarged when the laminated film was tilted from the homogeneous plane.
Retardation at 60 inclination was 77 nm. The haze of this film a~ measured by a hazemeter (Direct-reading Haze Computer HGM-2DP mfd. by Suga Shikenki Co., Ltd.) was 3.2%.
When the polycarbona~e retardation film obtained in Example 1 and said laminated film w~re laminated, the viewing angle became greater than 60~ and there was obtained a composite re~ardation film with a greater viewing angle than that of the single poly-carbonate retardation film.

,:, ~ ... ~ . ... . .

- 7~ -When this composit~ retardation film is placed between the upper polariz.ing plate and the corresponding liquid crystal cell of an STN type liquid crystal display device, black and white display is given and the film shows excellent viewing angle characteristics.
Said composite retardation film may be bonded to the upper polarizing plate of an STN type liquid crystal display device by a butyl acrylate type binder, and in this case, too, the film shows excellent visual field characteristics.

Example 7 The prccedure of Example 6 was carried out except for use of 8 wt% of 4-cyano-4'-ootyloxybiphenyl in place of 4-cyano-4'-hexylbiphenyl to obtain a laminated film of an oriented liquid crystal oligomer polymer composition and a polymeric substance. The obtainèd laminated film became extinct under crossed nicols and showed retardation of 5.3 nm which was supposed to be due to cellulose triace~ate, bu~
retardation enlarged when the film was tilted from the homogeneous plane. Retardation at 60 inclination was 50 nm. The haze of this laminated film as measured by a hazemeter was 1.4%.
When the polycarbonate retardation film and said laminated film were laminated, the viewing angle became great~er than ~0 and there was obtained a com-posite retardation film with a greater viewing angle ~,, . . ~ .. .. . . . .
. .
.,.. ~ ... . .. . . .

: ,::~. .: ~ -., -, ., .,, .,. . .. . .. ..... . .. ~ ..

than that of the single polycarbonate retardation film.
When this composite retardation film was placed betw~en the upper polarizing plate and the corresponding liquid crystal cell of an STN type liquid crystal display device, black and white display was given and the film showed excellent viewing angle characteristics.

Example 8 A 7% aqueous solution of polyvinyl alcohol (Poval 117, produced by Kuraray Co., Ltd.) was coated on an 80 ~m thick cellulose triacetate film and dried in 100C hot air. The formed polyvinyl alcohol film was 2 ~m thick.
The 5-membered ring pentasiloxane liquid crystal oligomer obtained in Example 1 was dissolved in methylene chloride to a concentration of 10 wt%, and in this solution was mixed 4--methoxybenzophenone in an amount of 10 wt~ per 100 wt% of liquid crystal oligomer.
Further, Irgacure 907 as a photopol~merization initiator was mixed in an amount o~ 2% based on the weight of the liquid crystal oligomer. The thus prepared solution was coated on a poly~inyl alcohol-coated cellulose tri-acetate film by using a bar coater. The obtained oriented liquid c~ystal oligomer composition film was cloudy.
The thus ob~ained three-layer (liquid crystal oligomer composi~ion/polyvinyl alcohol/cellulose ~ri--- ~o --ac0tate) laminaked ~ilm was heated in a 55C thermostat for 5 minutes and then irradiated w.ith light from a high pressure mercury lamp at alight intensity of 500 mW/cm2 on the irradiated surface.
The obtained laminated film of oriented liguid crystal oligomer polymer composition and polymeric substance became extinct under crossed nicols and showed retardation of 5.3 nm which was supposed to be due to cellulose triacetate, but retardation enlarged when the film was tilted from the homogeneous plane. Retardationat 60 inclination was 55 nm. The haze of the film as measured by a hazemeter was 2.2%.
When this laminated film and the polycarbonate retardation film used in Example 6 were laminated, the viewing angle became greater than 60 and there was obtained a compo~ite retardation film with a greater viewing angle than that of the single polycarbonate retardation film.
Also, when this composite retardation film is placed between the upper polarizing plate and the corresponding liquid crystal cell of an STN type liquid crystal display device~ black and white display is given and the film shows excellent viewing angle character-istics.

Example 9 The procedure of Example 6 was followPd except for use of 3 wt% of octadecyl methacrylate in place of 4-cyano-4'-hexylbiphenyl to obtain a laminated film of an oriented liquid crystal oligomer polymer composition film and a polymeric subst~nce. The obtained laminated film became extinct under crossed nicols and ~howed retardation of 5.3 nm which was supposed to be attri-butable to cellulose triacetate, but retardation enlarged when the film was tilted from the homogeneous plane. Retardation at 60 inclination was 70.0 nm. The haze of the film as measured by a hazemeter was 1.8%.
When the polycarbonate retardation film used in Example 6 and said laminated film were laminated, the viewing angle became greater than 60 and there was obtained a composite retardation film with a greater viewin~ angle than that of the single polycarbonate phase difference film.
When this composite retardation film is placed between the upper polarizing plate and the corresponding liquid crystal cell of an STN type liquid crystal display device, black and white display is given and the film shows excellent viewing angle characteristics.

Example lO
The procedure of Example 6 was followed except that no polycarbonate retardation film was laminated to obtain a laminate of an oriented liquid crystal oligomer polymer film and a hydrophilic substrate. ~hen this laminate is placed between a polarizing plate and the corresponding liquid crystal cell of a homogeneously oriented ECB type liquid crystal display device, it shows excellent viewing angle characteristics.

Comparative Example 2 The procedure of Example 6 was followed except that no heat treatment was conducted after coa~ing of the liquid crystal oligomer composition to obtain a laminated film of a liquid crystal oligomer polymer composition and a polymeric substance. The obtained laminated film was cloudy.
When observed under crossed nicols, the laminated film was cloudy and it was found that the liquid crystal oligomer polymer composikion was not oriented vertically.

Example 11 4-(allyloxy)-benzoic acid-4~-cyanophenyl ester was reacted with pentamethylcyclopentasiloxane in the same way as described in USP 4,410,570 ko obtain a polymer having a cyclic pentasiloxane liquid crystal oligomer as main structural unit. This liquid crystal polymer showed the nematic phase and its liquid phase/isotropic phase transition temperature was 97C.
This liquid crystal polymer was dissolved in acetone to a concentration of 15 wk%. A glass substrate was subjected to ultras~nic cleaning with a detergen~ (Clean Ace produced by Shoko Tsusho Co., Lkd.). The contact angle of this substrate against water was 30~3O The ~ 83 -liquid crystal polymer solution was coated on this glass substrate by a spin coater (lH-DX, Mikasa Co., Ltd.) and dried.
'rhe obtained liquid crystal polymer film was cloudy. ~he glass substrate wa heated on a 130C hot plate for 10 minutes. Then, w:ith the glass substrate left on the hot plate, the hot plate was switched off and the glass substrate was cooled gradually down to room temperature over a period o~ 4 hours. The cooled liquid crystal polymer was transparent under crossed nicols and showed zero retardation, but as retardation appeared when the liquid crystal polymer film was tilted from the homogeneous plane, it was found that the film was oriented vertically.
A 185 ~m thick polycarbonate base film was obtained by solvent casting, and this base film was stretched 2.1 times at 184C by transverse uniaxial stretchingO The obtained polycarbonate phase difference film was 98 ~m thick and its viewing angle l~ = 1.10) was 31, with R(0) = 572 nm.
When this polycarbonate retardation film and the liquid crystal polymer film on the glass substrate were laminated, the viewing angle was greater than 45 and there was obtained a composite retardation film with a greater viewing angle than that of the single poly-carbonate retardation film.
Thi.s enlargemen~ of viewing angle is indi-cative o homeotropic orientation of the liquid crystal l, . ,; .

- 8~ -polymer film.

Comparative Example 3 The process of Example 11 was carried o~t except that the glass substrate coated with the liquid crystal polymer wa~ not heated to obtain a liquid crystal polymer film. When observed under cros~ed nicols, the obtained liquid crystal polymer film showed a minute Schlielen texture.
This liquid c.rystal pol~mer film and the retardation film obtained in Example 11 were lamina~ed to obtain a composite retardation film. This composite retardation film, when observed visually, was cloudy.
Its viewing angle was 32.7, not much different from that of the liquid crystal polymer film.

Example 12 When a glass substrate was subjected to oxygen plasma ~reatment, its contact angle against water became 5.2. A 1.1 ~m thick liqllid crystal polymer film was obtained by following the same procedure as Example 11 except that the film was made hydrophilic. This liquid crystal polymer film and the retardation film obtained in Example 11 were laminated to obtain a composite retardation film. The viewing angle of this composite retardation film was over 45, greater than that of the original retardation film.

Example 13 When a glass substrate was treated with a silane coupling agent (AY43-02:L produced by Toray Silicone Co., Ltd.) to make it hydrophobic, the contact angle against water became 87.4. A 1.5 ~m thick liquid crystal polymer film was obtained in the same way as ~xample 11 except that the glass substrate, after heating, was placed on a 20C ~tainless plate and cooled quickly. This liquid crystal retardation film and the retardation film obtained in Example 1 were laminated to obtain a composite retardation film. The viewing angle of this composite retardation film was over 45, greater than that of the original retardation film.

Example 14 Polyvinyl alcohol (for oriented liquid crystal film, produced by EHC Inc.) was spin coated on a glass substrate to obtain a polyvinyl alcohol substrate. The contact angle of this substrate against water was 45.2.
An acetone solution of the same liquid cryskal polymer as used in Example 1 was spin coated on said polyvinyl alcohol substrate, followed by the same heat treatment as conducted in Example 11 to obtain a 0.7 ~m thick liquid crystal pol~mer film. The viewing angle of this composite retardation film was 37.5, greater than that of the original retardation film.

, 1 ;. , . , - ~6 -Example 15 The polycarbonate base f.ilm used in Example 11 was bonded to a glass substrate and subjected to ultra-sonic cleaning with a detergent, and polyvinyl alcohol was coated thereon in the same way as Example 14. The contact angle of this substrate against water was 45.2.
A liquid crystal polym~r film was formed on this substrate according to the process of Example 4 and then heat treated in the same way as Example 11 to obtain a 1.6 ~m thick liquid cxystal polymer film. This liquid crystal polymer film and the polycarbonate retardation film obtained in Example 1 were laminated so that the delayed phase axes of the respective films would agree with each other to obtain a composite retardation film.
The viewing angle of this composite retardation film was 32.0, greater than that of the composite retardation film obtained in Comparative Example 4.

Comparative Example 4 The polycarbonate base used in Example 11 was bonded to a glass substrate. Then this polycarbonate base-bonded substrate and the polycarbonate retardation film with R = 512 nm made in the same way as Example 1 were laminated so that the delayed phase axes of the respective films would agree with each other to obtain a composite retardation film. The viewing angle of this composite retardation film was 29.01. Thus, the viewing angle became smaller when the two polycarbonate films wexe laminated so that their delayed phase axes would agree with each other.

Comparative Example 5 A polycarbonate base film was treated according to Example 15 except that no polyvinyl alcohol was coated. Xts contact angle against water was 80.5.
An acetone solution of a liquid crystal polymer, same as used in Example 11~ was spin coated on said substrate to obtain a liquid crystal polymer film. This film was heat treated according to Example 11 or Example 13, but as observed under crossed nicols, it showed a Schlielen texture and was no~ oriented vertically. This liquid crystal polymer film on polycarbonate substrate and the re~ardation film obtained in Example ll were laminated so that their delayed phase axes would agree with each other to obtain a composite retardation film. This composite retardation film was cloudy, and its viewing angle differed from place to place of the film, indicat-ing that this film was impractical.

.
~xample 16 A cleaned glass substrate was masked with a cellophane adhesive tape and set in an evaporator.
Evaporation was carried out by ad~usting the substrate angle so that the evaporated SiO2 would be applied to the substrate at an angle of elevation of 10 from th~
substrate surface. Evaporation pressure was below 3 x !, ,~ ,i . . ':'. . ' ,.

10-3 Pa. After e~aporation, the cellophane adhesive tape was removed and the coated substrate was washed with acetone. The S102 coating film was 500 nm thick.
4-(allyloxy)-benzoic acid-4'-methoxyphenyl ester was reacted with pentamethylcyclopentasiloxane by the method shown in USP 4,410,570 to obtain a cyclic pentasiloxane liquid crystal polymer. This liquid crystal polymer showed nematic phase. This po~mer was dissolved in methylene chlorideto a 10% concentration and the solution was spin coated on the SiO2-coated substrate.
The obtained laminate wafi cloudy when observed under crossed nicols and 1.8 ~m ~hick. The obtained film was heated at 60C for 3 minutes and then observed under crossed nicols. It was found that at the SiOz-deposited area, the liquid crystal polymer was uniformly oriented.
Fig. 2 shows diagrammatically the direction o evaporation and the inclination axis at the time of measurement of transmitted light in~ensity, and Fig. 3 shows change of transmitted light intensity when the inclination axis was tilted. From Fig. 3, it i~ seen that extinction takes place when the laminate is turned 30~ about the inclination axis b, and that the liquid crystal polymer is orien ed with an inclination of 60, in terms of angle of elevation, from the film plane.

- 89 _ ~ I , .i~,,;
Comparative Example 6 The procedure of Example 16 was followed except that the portion of the glass substrate masked with a cellophane adhesive tape was used as substrate.
The obtained laminate, as examined under crossed nicols, had a Schliel0n texture. Since no extinction zone was observed when the laminate was turned in the substrate plane, it was confirmed that the laminate was not oriented in the substrate plane. It was also found that since no e~tinction zone was admitted when the laminate was tilted about the inclination axis a or b, the laminate had no slant orientation.

~xample 17 A 10% aqueous solution of polyvinyl alcohol (Poval 117, Kuraray Co., Ltd.) was coated on an 80 ~m thick cellulose triacetate film and dried in 100C hot air. The polyvinyl alcohol coating was 2 ~m thick. The procedure of Example 16 was followed except that ~he obtained film was used as su~strate to obtain a laminate of an oriented liquid crystal polymer film and a substrate.
The obtained laminate was cloudy and 1.8 ~m thick. The obtained film was heated at 60C for 3 minutes and then observed under crossed nicols. It was found that the liquid crystal polymer was uniformly oriented at the portion where SiO2 was deposited.
Fig. 2 shows diagrammatically the direction of - 9 o e~aporation and the inclination axis at the time of measurement of transmitted light intensity, and Fig. 4 shows change of transmitted light intensity when ~he laminate was turned about said inclination axis. I~ is seen from Fig. 4 that extinction occurs when the laminate is turned 30 about the inclination axis b, and that the liquid crystal polyme:r is oriented with an inclination of 30 from the di:rection normal to the laminate.
By using the oriented liquid crystal polymer film or oriented liquid crystal oligomer polymer film with the optical axis inclined 10-80, in terms of angle of elevation, from the film plane accordin~ to the present invention, or by laminating such film and a transparent or semitransparent film of a polymeric substance or combining said film with a uniaxially oriented retardation film, it is possible to obtain a composite retardation plate with a large viewing angle.
Also, by applying said film or laminate to an STN type liquid crystal display device, it is possible to remarkably improve the display characteristics, especially viewing angle charact~ristics, of the display device.
By using an optically anisotropic film having the optical axis substantially parallel to the normal line of the film, or by laminating such film and a transparent or semitransparent film of a polymeric substance, or by combining said film with a uniaxially - . ~ . .

l ,; .;
1: .!

oriented retardation film, it is possible to obtain a composite retardation plate with a large viewing angle.
Further, by using an oriented optically anisotropic film having the optical axis inclined 10-80 from the film plane, or by laminating such film and a transparent or semitransparent film of a polymeric substance, or by combining said film with a uniaxially oriented retardation film, there can be obtained a composite retardation plate with a large ~iewing angle.
Also~ by applying said film or laminate to an STN type or homogeneously aligned ECB type liquid crystal display de~ice, it is possible to remarkably improve the display characteristics, especially viewing angle characteristics, of the display device.

Example 18 On the same polycarbonate retardation film as used in Example 1, a stable colloid of partially hydrolyzed silicon tetrachloride was coated using a bar coater #9 and air dried. ~he same liquid crystal oligomer as used in Example 1 was dissolved in toluene so as to make the concentration 20%, followed by dissolution of Irgacure 907 Imfd. by Ciba-Geigy AG~ as a photopolymerization initiator in an amount of 2% based on the weight of the liquid crystal oligomer. The resulting so].ution was coated on the above-mentioned substrate using a bar coater #9 and dried at room temperature to gi~e a liquid crystal oligomer film of -- 9~ --2.5 ~lm thick. The resulting liquid crystal oligomer film was clouded in white.
A laminate film comprising the resulting aligned liquid crystal oligomer and a substrate was heat treated at 80C for 5 minut~s, followed by irradiation with ultraviolet light at 2 J/cm7 ~rom a high-pressure mercury lamp.
The resulting laminate of aligned polymerized liquid crystal oligomer and substrate showed 380 nm due to the retardation film. When this laminated film was inclined using the optical a~is of the retardation film as an inclination axis, the retardation hardly changed.
The viewing angle was 60 or more, and greatly improved compared with the case of single use of the retardation ~ilm.
When this laminated film of aligned polymer-ized liquid crystal oligomer and substrate is placed between the upper polarizing plate and the liquid crystal cell of an STN type liquid crystal display device, black and white display is given and the film shows excellent viewing angle characteristics.

Example 19 On the same polycarbonate retardation film as used in Example 1, a hard coat agent (Sumiflex XR-11, a trade name, mfd. by Sumitomo Chemical Co.~ Ltd.) was coated using a bar coater #9 to form a film of about 5 ~m, followed by photo curing. The resulting film wa~

~, ,1,, :, ... ' ~

plasma treated in an Ar gas. The same liquid crystal oligomer as used in Example 1 was dissolved in toluene so as to make the concentration 20%, followed by dissolution of irgacure 907 (mfd. by Ciba~Geigy AG) as a photopolymerization initiator in an amount of 2~ based on the weight of the liquid crystal oligomer. The resulting solution was coated on the above-mentioned substrate using a bar coater ~9 and dried at room temperature to give a liquid crystal oligomer film of 2.1 ~m thick. The resulting liquid crystal oligomer film was clouded in white.
A laminated film comprising the resulting aligned liquid crystal oligomer and a substrate was heat treated at 80C for 5 minutes, followed by irradiation with ultraviolet light at 1 J~cm2 from a high-pressure mercury lampO
The resulting laminate of aligned polymerized liquid crystal oligomer and substrate showed 380 nm due to the retardation film. When this laminated film was inclined using the optical axis of the retardation film as an inclination axis, the retardation hardly changed.
The viewing angle was 60 or morel and greatly improved compared with the case of single use of the retardation film.
When this laminated film of aligned polymer ized liquid crystal oligomer and substrate is placed between khe upper polarizing plate and the liquid crystal cell of an STN type liquid crystal display - :
.~.-.: :: ~ " :
,~
.

., 1., ., ~ .....

device, black a~d white display is given and the film shows excellent viewing angle characteristics.

Example 20 On the same polycarbonate retardation film as used in Example 1, a hard coat agent of ultraviolet light curable acrylic series wlas coated using a bar coater #9, air dried, and cured by irradiating ultra-violet light at 3 J/cm2. The same liquid crystal oligomer as used in Example 1 was dissolved in toluene so as to make the concentration 20%, followed by dissolution of Irgacure 907 (mfd. by Ciba-Geigy AG) as a photopolymerization initiator in an amount of 2% based on the weight of the liquid crystal oligomer. The resulting solution was coated on ~he above mentioned substrate using a bar coater #8 and dried at room temperature to give a liquid crystal ~ligome~ film of 3 ~m thick. The resulting liquid crystal oligomer film was clouded in white.
The resulting composite retardation film was heat treated at 80C for 5 minutes, followed by irradiation with ultraviolet light at 1 J~cm2 from a high-pressure mercury lamp.
The resulting composite retardation film showed 380 ~n due to the retardation film. When this composite retardation film was inclined using the optical axis o~ the retardation film as an inclination axis, the re-tardation hardly changed. The viewing angle ',; ,1..., . ".. . .
- 95 ~
was 60 or more, and greatly improved compared with the case of single use of the retardation film.
When this composite retardation film i~ placed between the upper polarizing plate and the liquid crys-tal cell of an STN type liquid crystal display device,black and white display is ~iven and the composite film shows excellent viewing angle characteristic~.

Example 21 A cellulose triacetate film of 80 ~m thick (Fijitax SH-80, a trade name, mfd. by Fuji Photo Film Co., Ltd.) was subjected to saponification treatment on the surface to gi~e an optically transparent and isotropic polymer substrate. On this substrate, a 30 toluene solution of polymerizable liquid crystal oligomer obtained in Example 1 was coated by a gravure coating method so as to form a film of 2.8 ~m thick after dried. After heat treating at 80C for 2 minu~es for homeotropic alignment, ultraviolet light o~ ~0O
mJ/cm2 as an integrated light amount was irradiated to give a polymerized liquid crystal oligomer/polymer laminated film ha~ing an isotropic in-plane refractive index, which is smaller than the refractive index in the thickness direction.
Furtherf as a uniaxially oriented retardation film, a unia~ially oriented retarda~ion film having an in-plane retardation of 428 nm (Sumicalight SEF-360428, a trade name, mfd. by Sumitomo Chemical Co., Ltd.) was ,:, . : - .

used.
Two retardation films were obtained by laminating khe polymerized liquid crystal oligomer/
polymer laminated film and the uniaxially oriented retardation film using an adhesive (construction:
cellulose triacetate film/pol~nerized liquid crystal layer/polycarbonate uniaxially oriented film).
The resulting retardation films were placed between the liquid crystal cell and upper and lower polarizing films, respectively, in a FTN type liquid crystal display (FTN ~ype LCD), mounted in a word processor (OASYS 301,X-401, a trade name, mfd. by Fujitsu, Ltd.) 50 as to face the polycarbonate unia~ially oriented film to the liquid crystal cell.
The FFN type ~CD was small in change of contrast by means of the viewing angle, and particularly symmetrical, and showed wide viewing angle character-istics in the directions of a~imuth angles o 60, 120, 240 and 300.
Iso-contrast curves are shown in FigO 5.
The iso-contrast cur~es were obtained by measurement using a device LCD-7000 ~a trade name, mfd.
by Otsuka Denshi Co.) by a tr~nsmitting method.
The voltage applied to the liquid cxystal display device was controlled so as to obtain the best contrast when viewed by the naked eye from the frvnt of the liquid crystal display device under practically drivin~ state. Further, the retardation of ~he - :, : . : : .: . ,,-, ~ ~

, . . ' =: . ~

uniaxially oriented retardati.on film in this Example was obtained from the maximum wavelength of interference spectra using a spectrometer (MCPD-1000, a trade name, mfd. by Otsuka Denshi Co., Ltd.) wherein two polarizing prisms were placed in parallel in the optical system.

Example 22 A FTN type LCD was produced in the same manner as described in Example 9 except that ~he film thickness of the polymerized liquid crystal layer of polymerized liquid crystal oligomer/polymer laminated film was made 3.3 ~m. The FTN type LCD was small in change of con-trast by means of viewing angle and showed good viewing angle characteristics. The iso-contrast curves are shown in FigO 6.

::. :

Claims (45)

1. An optically anisotropic film comprising a polymer of a liquid crystal oligomer having positive anisotropy of refractive index and showing nematic or smectic phase, said liquid crystal oligomer being selected from linear-chain or cyclic liquid crystal oligomers mainly composed of the following recurring units (I) and (II):

(I) (II) wherein A is a group represented by the following formula (III) or (IV):

(III) (IV) wherein, in the formula (III), -Si-O- is a main chain of the recurring unit (I) or (II) and, in the formula (IV), -C-CH2- is a main chain of the recurring unit (I) or (II) and COO group is positioned in side chain which is neither R1 nor R2; when A in the formula (I) is the formula (III) and when A in the formula (II) is the formula (III), R1 and R2 are independently hydrogen, a C1-6 alkyl group or a phenyl group, and when A in the formula (I) is the formula (IV) and when A in the formula (II) is the formula (IV), R1 and R2 are independently hydrogen or a C1-6 alkyl group; k and k' are independently an integer of 2 to 10; m and m' are independently 0 or 1; Ar1, Ar2, Ar3 and Ar4 are independently a 1,4-phenylene group, a 1,4-cyclohexylene group, a pyridine-2,5-diyl group or a pyrimidine-

2,5-diyl group; L and L' are independently CH2-O-, -O-CH2-, -COO-, -OCO-, -CH2-CH2-, -CH=N-, -N=CH- or a divalent group represented by the formula:
(V) p and p' are independently 0 or 1; R is halogen, a cyano group, a C1-10 alkyl group or a C1-10 alkoxy group; and R' is hydrogen or a C1-5 alkyl group), wherein when the numbers of the recurring units (I) and (II) in one molecule of said oligomer are supposed to be n and n', respectively, n and n' are each an integer of 1 to 20 and satisfy the relation of 4 ? n + n' ? 21, and further characterized in that the terminal group of the recurring unit (II) is polymerized, and that the optical axis of said film is aligned in the direction of an angle selected from between 0 and 80° against the normal line of the film.
2. An optically anisotropic film according to Claim 1, wherein the film comprises a polymerized liquid crystal oligomer and a low-molecular weight compound, said low-molecular weight compound being at least one compound selected from the group consisting of the compounds of the formulae (VI), (VII) and (VIII):

R3-Ar1-(L)p-Ar2-R4 (VI) wherein Ar1 and Ar2 are independently a 1,4 phenylene group, a 1,4-cyclohexylene group, a pyridine-2,5-diyl group or a pyrimidine-2,5-diyl group; R4 is halogen, a cyano group, a methacryloyl group, an acryloyl group, a C1-20 alkyl group or a C1-20 alkoxy group; L is -CH2-O-, -O-CH2-, -COO-, -OCO-, -CH2-CH2-, -CH=N-, -N=CH-, a 1,4-phenylene group or a divalent group represented by the formula (V); p is 0 or 1; and R3 is C3-30 alkyl group or C3-30 alkoxy group;

(VII) wherein R5 and R6 are independently hydrogen, C1-20 alkyl group or C1-20 alkoxy group; and m and ? are indepen-dently 0 or 1;

CH2 = C(R7)-COOR8 (VIII) wherein R7 is hydrogen or methyl group; and R8 is C1-30 hydrocarbon group;
the composition of said film being 100 parts by weight of said liquid crystal oligomer and 0.1-40 parts by weight of said low-molecular weight compound.

3. An optically anisotropic film according to Claim 1, wherein the optical axis of said film is aligned substantially parallel to the normal line of the film plane.

4. An optically anisotropic film according to Claim 1, wherein the optical axis of said film is inclined 10°-80°, in terms of angle of elevation, from the film plane.

5. An optically anisotropic film comprising a side chain type liquid crystal polymer having positive anisotropy of refractive index and showing nematic or smectic phase, said liquid crystal polymer being a linear-chain or cyclic liquid crystal polymer composed of the following recurring units (IX):

(IX) wherein A is a group represented by the following formula (X) or (XI):

(X) (XI) wherein in the formula (X), -Si-O- is a main chain of the recurring unit (IX) and, in the formula (XI), -C-CH2- is a main chain of the recurring unit (IX) and a COO group is positioned in the side chain which is not R1; when A in the formula (IX) is the formula (X), R1 is hydrogen, a C1-6 alkyl group or a phenyl group, and when A in the formula (IX) is the formula (XI), R1 is hydrogen or a C1-6 alkyl group; k is an integer of 2 to 10; m is 0 or 1; p is 0 or 1, Ar1 and Ar2 are indepen-dently a 1,4-phenylene group, a 1,4-cyclohexylene group, a pyridine-2,5-diyl group or a pyrimidine-2,5-diyl group; L is -CH2-O-, -O-CH2-, -COO , -OCO-, -CH2-CH2-, -CH=N-, -N=CH- or a divalent group represented by the formula ; and R is hydrogen, halogen, a cyano group, a C1-10 alkyl group or a C1-10 alkoxy group, characterized in that the number of the recurring units is 4-10,000 on the average per one molecule of the polymer, and that the optical axis of said film is inclined 10°-80°, in terms of angle of elevation, from the film plane.

6. A process for producing an optically anisotropic film set forth in Claim 1, which comprises forming a film of a linear-chain or cyclic liquid crystal oligomer composed of the recurring units (I) and (II), heat-treating said film so that the optical axis of the film is aligned substantially parallel to the normal line of the film, and then polymerizing the terminal group of the recurring unit (II).

7. A process for producing an optically anisotropic film set forth in Claim 1, which comprises forming a film of a linear-chain or cyclic liquid crystal oligomer composed of the recurring units (I) and (II) on substrate subjected to an alignment treatment, heat-treating said film so that the optical axis of the film is aligned 10°-80°, in terms of angle of elevation, from the film plane and then polymerizing the end group of recurring unit (II).

8. A process for producing an optically anisotropic film set forth in Claim 5, which comprises forming a film of a linear-chain or cyclic liquid crystal polymer composed of the recurring units (IX) on substrate subjected to an alignment treatment, and heat-treating said film so that the liquid crystal polymer is oriented 10°-80°, in terms of angle of elevation, from the film plane.

9. A process for producing an optically anisotropic film according to Claim 7, wherein the alignment treatment of the substrate comprises oblique evaporation of an inorganic material.

10. A laminate of an optically anisotropic film and a hydrophilic substrate, which comprises an optically anisotropic film set forth in Claim 1 and a transparent or semitransparent substrate which is hydrophilic at the surface.

11. A laminate of an optically anisotropic film and a hydrophilic substrate according to Claim 10, wherein the substrate is a glass plate, a hydrophilic polymer film, or a laminated film consisting of a hydro-philic polymer and a transparent or semitransparent polymer film.

12. A process for producing a composite retardation film, which comprises forming a film of a linear-chain or cyclic liquid crystal polymer composed of the recurring units (IX) and showing nematic or smectic phase on a uniaxially oriented retardation film having the optical axis in the film plane, said retarda-tion film also having positive anisotropy of refractive index and made of a thermoplastic polymer, and heat-treating said film at a temperature above the liquid crystal phase/isotropic phase transition temperature of said liquid crystal polymer.

13. A process for producing a composite retarda-tion film, which comprises forming a film of a linear-chain or cyclic liquid crystal polymer composed of the recurring units (IX) and showing nematic or smectic phase on a substrate having a glass transition temper-ature higher than the liquid crystal phase/isotropic phase transition temperature of said liquid crystal polymer, heat-treating said film at a temperature above the liquid crystal phase/isotropic phase transition temperature of said liquid crystal polymer, and laminating said substrate having a film of said liquid crystal polymer formed thereon and a uniaxially oriented retardation film having the optical axis in the film plane, said film also having positive anisotropy of refractive index and made of a thermoplastic polymer.

14. A process for producing a composite retardation film according to Claim 13, wherein the substrate is a polarizing film.

15. A laminate of an optically anisotropic film and a substrate according to Claim 10, wherein the substrate is a retardation film having the optical axis in the film plane, also having positive anisotropy of refractive index and made of a thermoplastic polymer, and the refractive index of the laminate is defined by the following formula:

nx > nz > ny (1) wherein nx and ny are the maximum value and the minimum value, respectively, of the in-plane refractive index of the laminate, and nz is refractive index in the thick-ness direction of the laminate.

16. A composite retardation plate comprising, as laminations, a uniaxially oriented retardation film having the optical axis in the film plane, also having positive anisotropy of refractive index and made of a thermoplastic polymer/ and a laminate of an optically anisotropic film and a hydrophilic substrate set forth in Claim 10, characterized in that the refractive index of said composite retardation plate is defined by the following formula:

nx > nz > ny (1) wherein nx and ny are the maximum value and the minimum value, respectively, of the in-plane refractive index of the composite retardation film, and nz is refractive index in the thickness direction of said film.

17. A laminate of an oriented liquid crystal polymer film and a substrate, comprising an optically anisotropic film set forth in Claim 4 and a transparent or semitransparent oriented substrate.

18. A laminate of an optically anisotropic film and a substrate according to Claim 17, wherein the substrate is a uniaxially oriented retardation film having an optical axis in the film plane, also having positive anisotropy of refractive index and made of a thermoplastic polymer.

19. A composite retardation plate comprising, as laminations, a uniaxially oriented retardation film having the optical axis in the film plane, also having positive anisotropy of refractive index and made of a thermoplastic polymer, and a laminate of an optically anisotropic film and a substrate set forth in Claim 17.

20. A composite retardation film having a polarizing film bonded thereto, characterized in that a polarizing film and a laminate of an optically ani-sotropic film set forth in Claim 1 or 5 or an optically anisotropic film set forth in Claim 10 or 17 and a hydrophilic substrate, or a composite retardation plate set forth in Claim 16 or 19, are bonded to each other with a binder or adhesive.

21. A liquid crystal display device characterized in that at least one of an optically anisotropic film set forth in Claim 1 or 5, a laminate of an optically anisotropic film and a substrate set forth in Claim 10 or 17, and a composite retardation plate set forth in Claim 16 or 19, is provided between a liquid crystal cell and a polarizing film disposed outside thereof, said liquid crystal cell comprising a liquid crystal layer held by the substrates having the electrodes, said layer also having positive dielectric anisotropy and oriented substantially homogeneously, with the helical axis torsionally aligned vertically to the substrate, when no voltage is applied, or a composite retardation film set forth in Claim 20 having a polarizing film bonded thereto is disposed on said liquid crystal cell.

22. A liquid crystal display device characterized in that at least one of an optically anisotropic film set forth in Claim 1 or 5 and a laminate set forth in Claim 10 or 17 is provided between a homogeneously aligned liquid crystal cell and a polarizing film disposed outside thereof, said homogeneously aligned liquid crystal cell being held by the substrates having electrodes, said cell also having positive dielectric anisotropy and having the major molecular axis aligned substantially parallel to the substrate when no voltage is applied.

23. A liquid crystal display device characterized in that at least one of an optically anisotropic film set forth in Claim 1 or 5, a laminate of an optically anisotropic film and a substrate set forth in Claim 10 or 17, and a composite retardation plate set forth in Claim 16 or 19, is provided between a liquid crystal cell and a polarizing film disposed outside thereof, said liquid crystal cell comprising a liquid crystal layer held by the substrates having the electrodes, said layer also having positive dielectric anisotropy and oriented substantially homogeneously, with the helical axis torsionally aligned vertically to the substrate, when no voltage is applied, or a composite retardation film set forth in Claim 20 having a polarizing film bonded thereto is disposed on said liquid crystal cell.

24. A process for producing an optically anisotropic film set forth in Claim 5, which comprises forming a film of a linear-chain or cyclic liquid crystal oligomer composed of the recurring units (I) and (II) on substrate subjected to an alignment treatment, heat-treating said film so that the optical axis of the film is aligned 10°-80°, in terms of angle of elevation, from the film plane and then polymerizing the end group of recurring unit (II).

25. A process for producing an optically anisotropic film according to Claim 8, wherein the alignment treatment of the substrate comprises oblique evaporation of an inorganic material.

26. A laminate of an oriented liquid crystal polymer film and a substrate, comprising an optically anisotropic film set forth in Claim 5 and a transparent or semitransparent oriented substrate.

27. A composite retardation film comprising a polarizing film bound to a uniaxially aligned retarda-tion film having positive anisotropy of refractive index and made from a thermoplastic polymer via an adhesive, and at least one layer of the optically anisotropic film of Claim 1 being present between the polarizing film and the retardation film, or one outerside or both outer-sides of the retardation film.

28. A composite retardation film according to Claim 27, wherein the optically anisotropic film is formed on a transparent or semi-transparent substrate.

29. A composite retardation film according to Claim 27, wherein the optically anisotropic film is formed on a uniaxially aligned retardation film having positive anisotropy of refractive index and made from a thermoplastic polymer.

30. A liquid crystal display device comprising a pair of transparent substrates having electrodes thereon and sandwitching a liquid crystal cell containing a nematic liquid crystal layer having positive dielectric anisotropy and oriented substan-tially horizontally with a helical axis aligned vertically to the substrate when no voltage is applied, a pair of polarizing films positioned outside a pair of the transparent electrodes, and at least one uniaxially aligned retardation film having positive anisotropy of refractive index and made from a thermoplastic polymer positioned between the liquid crystal cell and at least one of the polarizing films, and at least one layer of optically anisotropic film set forth in Claim 1 being present between the liquid crystal cell and at least one of the polarizing films.

31. A liquid crystal display device according to Claim 30, wherein the optically anisotropic film is formed on a transparent or semitransparent substrate.

32. A liquid crystal display device according to Claim 30, wherein the optically anisotropic film is formed on a uniaxially aligned retardation film having positive anisotropy of refractive index and is made from a thermoplastic polymer.

33. A liquid crystal display device comprising a pair of transparent substrates having electrodes thereon and sandwitching a liquid crystal cell containing a nematic liquid crystal layer having positive dielectric anisotropy and oriented substan-tially horizontally with a helical axis aligned vertically to the substrate when no voltage is applied, a pair of polarizing films positioned outside a pair of the transparent electrodes, and at least one uniaxially aligned retardation film having positive anisotropy of refractive index and made from a thermoplastic polymer positioned between the liquid crystal cell and at least one of the polarizing films, and at least one layer of optically anisotropic film set forth in Claim 2 being present between the liquid crystal cell and at least one of the polarizing films.

34. A liquid crystal display device according to Claim 33, wherein the optically anisotropic film is formed on a transparent or semitransparent substrate.

35. A liquid crystal display device according to Claim 33, wherein the optically anisotropic film is formed on a uniaxially aligned retardation film having positive anisotropy of refractive index and made from a thermoplastic polymer.

36. A liquid crystal display device comprising a pair of transparent substrates having electrodes thereon and sandwitching a liquid crystal cell containing a nematic liquid crystal layer having positive dielectric anisotropy and oriented substan-tially horizontally with a helical axis aligned vertically to the substrate when no voltage is applied, a pair of polarizing films positioned outside a pair of the transparent electrodes, and at least one uniaxially aligned retardation film having positive anisotropy of refractive index and made from a thermoplastic polymer positioned between the liquid crystal cell and at least one of the polarizing films, and at least one layer of optically anisotropic film set forth in Claim 5 being present between the liquid crystal cell and at least one of the polarizing films.

37. A liquid crystal display device according to Claim 36, wherein the optically anisotropic film is formed on a transparent or semitransparent substrate.

38. A liquid crystal display device according to Claim 36, wherein the optically anisotropic film is formed on a uniaxially aligned retardation film having positive anisotropy of refractive index and made from a thermoplastic polymer.

39. A liquid crystal display device comprising a pair of transparent substrates having electrodes thereon and sandwitching a liquid crystal cell containing a nematic liquid crystal layer having positive dielectric anisotropy and being homogeneously oriented in the almost horizontal direction when no voltage is applied, and a pair of polarizing films positioned outside a pair of the transparent electrodes, and at least one layer of the optically aniso-tropic film set forth in Claim 1 being present between at least one of the polarizing films and the liquid crystal cell.

40. A liquid crystal display device comprising a pair of transparent substrates having electrodes thereon and sandwitching a liquid crystal cell containing a nematic liquid crystal layer having positive dielectric anisotropy and being homogeneously oriented in the almost horizontal direction when no voltage is applied, and a pair of polarizing films positioned outside a pair of the transparent electrodes, and at least one layer of the optically anisotropic film set forth in Claim 2 being present between at least one of the polarizing films and the liquid crystal cell.

41. A liquid crystal display device comprising a pair of transparent substrates having electrodes thereon and sandwitching a liquid crystal cell containing a nematic liquid crystal layer having positive dielectric anisotropy and homogeneously oriented in the almost horizontal direction when no voltage is applied, and a pair of polarizing films positioned outside a pair of the transparent electrodes, and at least one layer of the optically aniso-tropic film set forth in Claim 5 being present between at least one of the polarizing films and the liquid crystal cell.

42. A liquid crystal display device comprising a pair of transparent substrates having electrodes thereon and sandwitching a liquid crystal cell containing a nematic liquid crystal layer having positive dielectric anisotropy and oriented substan-tially horizontally with a helical axis aligned vertically to the substrate when no voltage is applied, a pair of polarizing films positioned outside a pair of the transparent electrodes, and at least one uniaxially aligned retardation film having positive anisotropy of refractive index and made from a thermoplastic polymer positioned between the liquid crystal cell and at least one of the polarizing films, and at least one layer of optically anisotropic film set forth in Claim 3 being present between one of the retardation films adjacent to the retardation film and one of the polarizing films.

43. A liquid crystal display device according to Claim 42, wherein the optically anisotropic film is formed on a transparent or semitransparent substrate.

44. A liquid crystal display device according to Claim 42, wherein the optically anisotropic film is formed on a uniaxially aligned retardation film having positive anisotropy of refractive index and made from a thermoplastic polymer.

45. A laminate obtained by laminating an optically anisotropic film set forth in Claim 3 on a transparent or semitransparent substrate subjected to hard coat treatment.