CA1183605A - Metallized information carrying discs - Google Patents

Abstract

ABSTRACT

Most information carrying discs are made by impressing an information carrying surface onto a substrate and subsequently providing a metallic coating over the surface. This requires that disc manufacturers have sophisticated coating equipment and techniques. It has been found that premetallized blanks may be impressed with an information carrying surface so that only the manufacturer of the blanks is required to have coating technology.

Description

3~

METALLIZED INFORMATION CARRYING DISCS

TECHNICAL FIELD
_ _ The present invention relates to information carrying artlcles and more particularly to information carrying ~iscs which carry ligh~ readable or stylus read-able information. These discs may be useful in carrying coded information which is convertible ti.e.l electronically decoded) to electrical signals for such varied uses as sound recordings, audio/visual recordings~
or computer information retrieval systems. A process for forming these information carrying articles and blanks from which the articles may be made is also disclosed.

BACKGROUND ART
Information retrleval in the form of discs hav~
ing coded data distributed in a circular or spiral pattern has been available in various forms for many years. Early forms of musical re~roduction equipment, for example, used discs with either holes or protuberances to pluck an array of strings or vibrating posts to produce music. Early displays of moving pictures operated by a rotation of a disc bearing consecutive images on a periphery. The most common form of storing reproductions of music performances which has been in use for about 100 years, is the phono-graph record which uses a spiral pattern of grooves having vertical and horizontal modulations to generate signals which can be converted to sound.
With the introduction of the laser to industry, a new information storage system has been developed which comprises a disc having circular or spiral patterns of depressions or protuberances which would disturb, reflect or refract incident or transmitted light patterns. These information storing discs, often used for storage of audio/vis~al information and ge~erally referred to as video discs, are well known in the art. Such U.S. Patents 3S as 3,658,954; 3,795,534; 3,798,134; 3,855,426i 3,901,994;

:

4,124,67~; 4,126,716; and 4,130,620 show various constructions, compositions, and processes for forming video discs.
United States Patent No. 4,126,726 also shows the use of photocurable lacquersto form an image carrying surface and to pro-vide a protective cover over the information carrying surface when a reflective metal film is used. No information whatsoever with regard to the nature and properties of the radiation curable layer is provided. In all instances the reflective metal coatings are provided to the element after -the information is applied to its surface.

DISCLOSURE OF T~IE IN~IENTION
_ It has been found according to the present invention that information storage devices, which may compr~se d~scs having a circular or spiral pattern of grooves with modulations in a con-ductive or reflective metal layer, can be prepared from a blank element compris~ng a substrate which is or carried on at least one surface thereof a polymeric composition having a reflective or con-ducti~e coating on the surface of the coating before embossing~
Reflective or capac~t~ve v~deo discs may be formed from blanks such as these by an embossing process descr~bed herein The invent~on provides a coded information carrying structure capable of being electronically decoded comprising (1) a base, (2) a first layer of an electrically conductive or electromagnetic radiatIon reflective layer adhered to at least one surface of said base, sa;~d layer having coded information in the form of depressions in sai~d layer having ~een vertically d~splaced a distance of from 0~03 to 10~0 m~crometers, w~th said first layer having ruptures or necki:n~ on the sides of the depressions, and (3) an insulating or transparent protective layer over said first layer.
The invention also provides a two-sided information carrying structure comprising two bases, each base having a firs~ layer of an electrically conductive or electromagnetic radiation reflective layer adhered to one surface of each base, said first layers having coded information in the form of depressions in said layer having been vertically displaced a distance of from 0003 to 10.0micro-meters, with said 'irst layers having ruptures or necking on the sides of the depressions, said first layers being adhered together.
The invention further provides a process for forming an in-formation bearing article which comprlses embossing coded infor-mation which may be electronically decoded onto a mulilayered article comprising (a) a base having at least one thermoplastic surface and adhered onto said surface, (b) an electrically con-ductive layer or electromagnet~c radiation re~lective layer to form a coded ~nformation bearing surface on said layer, said coded information being formed by the vertical displacement of areas of said layer to a depth of 0.03 to 10~0 micrometers with said layer having ruptures or necking on the side of said depression.
BRIEF DESCRIPTION OF THE DRAWINGS
_ Figure I shows a side view of a video disc blank~
Figure II shows a side view o~ an embossed video disc blank with information carrying protu~erances and depressions thereon.
Figure III shows a si~de ~iew of the two embossed video disc blanks which have been ~oined to pro~ide a disc which carries two different retrie~able patterns of information. The embossed surfaces axe joined face to face.

- 2a p~
~3--FIGURE IV shows a side view o two embossed video disc blanks whoch have been joined back to back to provide a disc which carries two different retrievable patterns of information.
FIGU~E V shows a microscopic side view of an embossed video disc wherein a radiation reflecting or conductive metal film has been severed during embossing.
FIGURE VI shows a microscopic side view of an embossed video disc wherein a conductive or radiation reflective metal film has stretched or necked during embossing.

DETAILED DESCRIPTION OF THE DRAWINGS
Figure I shows a side view of an embossable video disc blank 2 comprisinq a base 4, a radiation reflec-tive or conductive metal layer or conductive non-metallic la~er 6, and an optional organic or inorganic (e.g., silica) polymeric protective coating layer 8. The base 4 may be unitary in construction or may be a composite layer such as a film layer having a further polymerizable or heat softenable coating layer on at least the surface adjacent to metal or non-metallic layer 6. The base 4 may be transparent or opaque and may comprise any material which can provide structural properties to the blank. If the base 4 itself is to be embossed to provide the information carrying surface structure, the composition of the base must be embossable and would be a thermoplastic or thermosoftenable material. If the base 4 carries an embossable layer on at least one surface thereof, the base 4 carrying the layer may be of metal, ceramic, fibrous, thermoplastic, thermoset, or filled polymeric materials, depending upon the manner in which the disc is read. If read by light reflection through the base, transparency would be required in the material selected.
Figure II shows a section of an embossed video disc 10 having a base 11 comprising a substrate 12 carrying a coating 14 which was given surface structure by the embossing step. A metal layer 16 which was on the coating 14 before the embossing also carries the surface structure which consists of depressions such as 18.
Figure III shows a section of a two sided video disc 20 comprising two separately prepared one sided video discs ?l and 21' which have been joined face to face by an adhesive layer 28. The one sided video disc 21 is shown as having been prepared from a blank having a base 23 comprising a substrate 22 and a coating 24 which carries the surface structure. A metal layer 26 on said coating 24 also displays the surface structure. The one sided video disc 21' i5 shown as comprising a single component base 32 on which the surface structure was embossed. A
metal layer 30 on base 32 also displays the surface structure. The adhesive 28 joins the metal layers 26 and 30. These metal layers may have polymeric coatings or layers between the adhesive 28 and the metal layers 26 and 30, but this is optional. As shown in this figure, the adhesive 28 does not have to penetrate into the air cavities 36 to form a bond between the t~o one sided discs, although by using thicker adhesive layers, this may be accomplished. The presence of air is inconsequential between the two discs because the radiation used to read the patterns would pass through the base layers 21 and 21 and be reflected off the metal layers 26 and 28 and would not pass through the area between the indentations 34 in the surface structures. The two one sided discs may be formed in the same or different manners. That is, the figure shows a two component base 21 and a one component base 21' merely as a representation of one possible construction. Both bases may be of the same or different types of construction, with both, of course, being transparent to the radiation used to retrieve information from the discs.
Figure IV shows a section of a two sided video disc 40 comprising a base 47 bearing information and a metal layer 48 on one surface and an embossed coating layer 46 with a metal layer 44 on the other surface. The embossed surface structures 52 and 54 face outward in this configur3tion. The information carrying surface struc-tures 52 and 5~ are coated with transparent protective layers 50 and 42 to prevent damaye to the metal layers and penetration of foreign materials into the pattern of the information carrying surface structure. Two separately embossed discs may be adhesively bonded or fused back to back, or the disc blank may have two metal coatings, one each on opposite surfaces, to produce corresponding structures with the surface structure facing outward.
Figure V shows a microscopic sectioned view o an embossed vide disc 60. The base 62 carries a metal layer 64 which has been ruptured where the embossing has formed a depression 67 and displaced a piece of metal 68 into the base. The rupture 66 on the edge of metal layer 64 overlooking the metal free side wall 70 of the depression 67 is shown.
Figure VI shows a microscopic sectioned view of ~0 an embossed video dlsc 80. The base 82 carries a metal layer 84 which has been stretched and nec~s at 86. This necklna 86 has been caused by the formation of depression 87 in which a piece of metal 88 has been displaced into base 82 but has not separated from the original metal layer 84 and the necking is contiguous to the sidewall 90 of the depression.

DETAILED DFSCRIPTION OF THE INVENTION
There are at least three aspects to the present inventionl the multilayered article used to form the coded information bearing articles, the coded information bear-ing articles which may be electronically decoded, and the process of makiny the coded information bearing articles.
It would be helpful towards an appreciation of the nature of the present invention if certain concepts and parameters were understood. For example, the term coded information means information tha~ can be read only by instrumenta-tion, as opposed to visual images, lettering, and visually readable symbols of any sort.
Surface modification of layers which produces variations in depth and consequent variations in conductivity and reflectivity is a conventional manner of providing coded information, as is the rearrangement of magnetic particles in other types of coded information bearing technologies.
This information is defined as coded because it is not understandable or translatable by a human reader except by mechanical intervention. Just as a photograph record requires the use of a phonograph to decode the modulations in the grooves, the coded information in the articles of the present invention require mechanical intervention, defined herein as electronic decoding, to convert the coded information into a form more readily useful to human audience. The terms electronic decoding or electronically decoded are defined as meaning that the coded information may be mechanically read, e.g., by reflected light, by capacitive voltage readout, and the like, and converted into e]ectrical signals which may be translated into information which may be directly perceived by a human being such as printing, sound, television display, etc~ The more preferred formats for electronical:Ly decoding the coded information bearing articles are capacitive readout and light reflective readout (especially from a laser) systems, such as those presently available for video discs, which produce an electrical signal which can be directly converted to another signal which can be projected and displayed on a television screen.
As all materials are conductive to some degree, the terms conductivity or conductive when used in reference to the coded information bearing layers define layers having a conductivity of less than 10,000 ohms per square, preferably less than 5000 ohms per square, and most preferably less than 2000 ohms per square.

Reflectivity must also be similarly considered, as most materials are reflective to some measurable degree. According .o the practice o the present invention, a layer or an article is defined as reflective when it reflects at least 50% of incident electromagnetic radiation within a 50 nm range. Preferably the layer will reflect at least 70 or 75% of such incident radiation, and most preferably will reflect at least 85% oE incident electromagnetic radiation within a 50 nm rangeO
Preferably the radiation which is used for measuring reflectivity is in the visible region o the electro-magnetic spectrum, but ultraviolet radiation, infrared radiation, and radio waves might be useful for reading certain coded information.
Coded information is embossed into the conductive or reflective layer by vertical displacement of portions of that layer. This may be done by embossing a continuous pattern in the layer or preferably by embossing a pattern of discrete areas in which the displaced areas are connected to each other by non-displaced areas which are generally flat and which generally correspond to the plane of the original unembossed layer and the unembossed areas generally have the thickness of the original unembossed layer. The conductive or reflective layer must be embossable. Because the invention generally tends to use as little material in that layer as possible, embossability can be effected for many different materials. When a layer, such as one of aluminum, titanium, vapor deposited carbon, conductive resin or particulate-filled resin is coated as a thin layer on a substrate, that thin layer, for most macromolecular operations, including embossing, tends to adopt the physical properties (particularly with regard to elasticity and conformability) of thP surface onto which it has been coated. This is particularly true for metal layers between 0.2 and 75 nm in thickness. Metal layers are defined as embossable when embossment with a pressure `

of no more than 150 kg/cm2 at a temperature of no more t~an 200C will cause a replication of the embossing stamper to form on both sides of the metal layer.
Replicability on the reverse slde of illed polymeric materials used as the conductive or reflective layer is not essential. When a metal layer is recited as the embossable reflective or conductive layer, the limitation of two sided replicability (although, of course, not with identical resolution) is included within the definition of the term embossable.
The disc blanks useful in the practice of the present invention comprise a base of an embossable mono-lithic layer or a substrate having on at least one surface thereof an embossable polymeric material and a reflective or electromegnetic radiation re~lective metal or non-metallic layer over said base. The embossable pol~meric material may be present on a substrate as a coating or layer of any reasonable size, preferably of from 2 to 400 microns in thickness~ The composition preferably has a maximum loss modulus (GmaX) which appears between the temperatures of 30 and 180C. This will enable the composition to be readily embossed at temperatures between 50 and 200(` (each temperature is 20C higher than GmaX) without being too soft at room temperature. Preferably GmaX will app~ar between 40 and 100C. Embossing is generally performed at a temperature at least 20C higher than G", preferably betwen 25 and 100C higher than G" to save energy. G (loss modulus~ is the out-of--phase component of the applied strain. This value represents the energy not stored elastically through the following relationship:
W = ( ~D ) 2G"
where W is the work per cycle under a given strain at a predetermined frequency (in radians/sec.), ~G iS the initial strain, and G is the loss modulus.
The polymeric layer may be thermoplastic or a heat-softenable radiation curable layer and has on its t~) _9_ e.~terior surface a reflective or conductive coating, preferably of metal between 0.2 and 200 nanometers in thickness and more preferably up to 75 nanometers in thick-ness. Preferably the coating is between 0~2 and 10.0 nm for a capacitive disc and 0.2 to 60 nm for a reflective disc~ Most preferably the coating is between 0.5 and 5 nm.
The base may be of any reasonable thickness, but is generally between 10 x 10-~ and 2 millimeter. The thermo-plastic or radiation curable layer should be at least 5 or 10.0 ~m thick and preferably at least 25 ~m thick. This i5 most important when this layer is a coating on a sub-strate. The reflective metal layer may comprise substan-tially any reflective metal such as chromium, alumium, silver, gold, nickel, iron, titanium, rhodium, tantalum, tin, indium, alloys thereof, etc. The conductive metal layer may be of any conductive metal which includes all o the above and essentially every metal. The conductive layer may also be of carbon, conductive polymers, and conductive particulate filled polymers.
There are at least two different formats for video discs which may benefit from practice of the present invention. One is the capacitive readout mode and the other is the laser readout mode. The laser readout mode requires a reflective surface on the information bearing layer and the capacitive readout mode requires a conductive surface on the information bearing layer and an insulating layer over the conductive sur~ace. The capacltive system, as is known in the art, requires a stylus to provide the ability to read -the information and requires an insulating layer between the stylus and the information bearing metal layer. The insulating material may be any insulating material, but is preferably an organic polymeric material. Some lubricating properties, in the layer itself or in a coating, are particularly desirable in the capaciti~e system. In the capacitive mode, the polymeric material obviously need not be transparent. The insulating surface of the capacitive disc may be grooved to provide tracking for the stylus or may be flat with a separate tracking means. The insulating layer may be applied before or after embossing.
The layer may be of from 1 to 100 nm thick and may be any S insulating material including polymeric materials and insulating oxides such as SiO2. Preferably the insulating layer is between 1 and 50 nm and may be applied by any conventional method including spin coating, sputtering, chemical evaporation, plasma polymerization, a~omization, etc. The insulating layer need not be perfectly flat.
When applied after embossing, for example, a definite variation in height of the layer over the surface structure can be seen and this modest variation does not adversely affect the information providing characteristics of the disc. As a matter of fact, the covering layer, being in some ways also a protective layer, is not of uniform thickness with respect to the surface of the layer and the coded in~ormation bearing layer and the vertically displaced areas. The only way in which uniformity could ~0 be readily effected would be by applying very thin layers of the protective material or by embossing a blank having the protective layer already thereon. That is, the thickness of the protective layer is different over the displaced areas from its thickness over non-displaced areas. Any variation from planarity which might exist in the surface of the layer (but which need not exist), does not exactly duplicate the variation in height or depth of the conductive or reflective layer, although with thin protective and/or insulating layers, the variations will bear some relationship to each other.
~ longst the useful radiation curable polymeric materials or use on at least one surface of a video disc blank may comprise a radiation curable thermoplastic polymer layer containing any addition polymerizable groups (e.g., ethylenically unsaturated materials such as acryloyl, methyacryloyl, allyl, acrylamido, etc., epoxy, e~g., ylycidyl, epoxycycloalkyl or epoxyal~ylhydantoin~.

Such curable thexmoplastic materials are disclosed for example in United States Patent Nos~ 4,309~529 and 4,304,705. Other such compositions are also known in the art. The thermoplastic materials described in the above two applications are preferred materials accordin~ to the practice of the present invention.
The curable polymers of said United States Patent No.
4,309,529 have repeating units of the general formula:

ORl O ORl O O
~W-C~ l 11 11 -O~CH2-C-R-N ~ ~ N-R-C-CH2-O-C-Q-C~ I
R O R (Z)a wherein R is a single bond or an alkylene group having 1 to 6 carbon atoms and optionally one catenary oxygen;
Rl is hydrogen but can be -C-R3 or -CNH-R4, wherein R3 is pre-ferably alkenyl but: can be alkyl having 2 to 5 carbon atoms and can be substituted by phenyl or carboxyl and R4 is aliphatic or aromat-ic hydrocarbyl having up to 8 carbon atoms and is preferably acryloyloxyalkyl or a methacryloyloxyalkyl group, in which the alkyl group has 2 to 4 carbon atoms;
R is hydrogen or methyl;
W is a divalent group that is required to complete a 5- or 6- mem-bered heterocyclic ring, preferably, W is 11 11 1 1 1 ll -C-, but W can be -C-~ -C-C-, -C--C-, or -C-NH-wherein R5 r R6, p~7 and R8 are independently hydrogen or loweralkyl of 1 to 4 carbon atoms;

Q is the divalent or trivalent residue of hydro-carbyl di- or tri-carboxylic acids, said residue formed by the removal of active hydrogens from the carboxylic acid groups and containing up to 40 carbon atoms, preferably containing 4 to 12 carbon atoms, and optionally containing catenary oxygen atoms~ of which carboxylic acids at least 10 mole percent have alpha-methylene groups;
a is zero or one, but can he one for no more than 20 mole percent of the carboxylic acids; and o Z is C-OH
These curable compounds generally can be prepared by the base catalyzed, preferably ~he tertiary amine catalyæed, reaction of one mole equivalent of a bis-(epoxy)heterocyclic compound and from about 0.8 to 1.2 mole equivalents of polycarboxylic acid (one or more dicarboxylic acids can be used) in accordance with the equation:

(b + 1) H2C - C-R-N'~W C~N-R-C ~ H2 + b HO-C ~ C-OH
p~2 ll R2 (Z)a o rH O O OH O ~
H~ ~ -R-N'W ~/N-R ~ H2-O-C~}~H~C-R-N'W C`N-R~ ~ H2 II
R2 C IR2 (Z)a R2 C !R2 O L o ¦b wherein R, R2, Q, a, Z, and W are as defined before and b is a number having a value between about 5 and 60 suffi-cient to provide the polyester with a number average 3~ molecular weigh-t between about 3,000 and about 30,000.
The catalyzed reaction, wherein a catalytically active amount of a base polymerization catalyst is util.ized, can be performed in the presence or absence of solvent. Generally, the epoxide, polycarboxylic acid, .a~tti -13~
catalyst, inhibitor for thermal ~olymerization, and solvent, i~ used, are heated from 50 to 120C, preferabl~
about 80 to 100C, until the disappearance of the epoxy group as may be shown by chemical titration anaylsis, is observed. Heating for frQm 2 to 40 hours usually suffices to complete the reaction.
The hydroxyl groups present in compounds of formula I (i.e., where Rl is hydrogen) can be acylated by treatment with an acylating agent, preferably by an acyl halide, an acyl anhydride, or an isocyanate that may contain polymerizable ethylenically unsaturated groups.
By adjustment of the ratio of bis-(epoxy)~
heterocyclic compound to dicarboxylic acid, the terminal groups in the polyester can be controlled as is known in the addition polymer art. Thus, an excess (about 1 to 10~) of the bis-epoxide over the dicarboxylic acid gives polyesters having terminal epoxy groups and as excess (about 1 to 10%) of the dicarboxylic acid over the bis-epoxide gives polyesters having terminal carboxylic groups. Essentially equivalent amounts of bis-epoxide and dicarboxylic acid give polyesters having~ on average, both carboxyl and epoxy terminal groups. When the terminal groups of th~e polyester are epoxy, these terminal groups are readily converted to acryloyl, methacryloyl or mixtures thereof by reaction with acrylic or methacrylic acid as is known in the art.
Suitable bis-epoxyheterocyclic compounds for use in the practice of the present invention have the formula:
\ W C'~O ,\
R2 \C / R2 III
o wherein R, R2 and W are as defined for Formula I.
Examples of suitable bis-(epoxy)heterocyclic compounds include:

1,3-diglycidylhydantoin 1,3-diglycidyl-~-amylhydantoin 1,3-diglycidyl-5-octylhydantoin 1,3-diglycidyl~5-methylhydantoln 1,3-diglycidyl-5,5-dimethylhydantoin 1,3-diglycidyl-5~ethyl-5-methylhydantoin 1,3-diqlycidyl-5-ethyl~5-hexylhydantoin 1,3~di(2-glycidyloxyethyl)-5,5-dimethylhydantoin 1,3-di(3-glycidyloxypropyl)-5,5-dimethylhydantoin 1,3-diepoxyethyl-5,5-dimethylhydantoin 1,3-diglycidyluracil 1,3-diglycidyl-6-methyluracil 1,3-diglycidyl-5,5-dimethyl-5,6-dihydrouracil 1,3-di(~-methylglycidyl)~5,5-dimethyl-5,6-dihydrouracil 1,3-diglycidylisocyanurate 1,3 diepoxyethylisocyanurate Other suicable bis-(epoxy)heterocyclic compounds are listed in U.S. Patents 3,808,226 and 4,137,139 which are incorporated into thls application by reference.
The preferred bis-(epoxy)heterocyclic compounds are the l,3-diglycidylhydantoins such as 1,3-diglycidyl-5,5-dimethylhydantoin, 1.3-diglycidyl-5-ethyl-5-methyl-hydantoin, 1,3-diglycidyl-5-hexyl-5~-methylhydantoin, and 1,3-di( 3-glycidyloxypropyl ) -5, 5-dimethylhydantoin.
Suitable polycarboxylic acids for use in the practice of this invenkion have 'che formula:

O O
Il 11 MO-C-Q-C OH
(Z)a where Q and a and Z are as defined for formula I. The polycarboxylic acids may be saturated or unsaturated, aliphatic, cycloaliphatic, aromatic, or heterocyclic and may be substituted optionally by non-interfering groups such as alkyls, unsaturated alkyls, heterocyclics, sulfonates, esters, ethers, halohydrocarbons, amides and carbamates~ Examples of suitable dicarboxylic acids include: oxalic, succlnic~ glutaric, adipic, suberic, sebacic, undecanedicarboxylic, hexadecanedicarboxylic, S 1,2,3-propanetricarboxylic, tricarballylic, dimerized fatty acids (such as obtained by the polymerization of oleinically unsaturated monocarboxylic acids containing 16 to 20 carbon atoms such as oleic acid, linoleic acid and the like. The dimer acid of linoleic acid is described in U.S. Patent 3,753,463). Other useful dicarboxylic acids are diglycolic, dilactic, 3,3'(ethylenedioxy)dipropionic, phthalic, i soph thal ic, terephthalic, 5-sulfonatoisophthalic, trimellitic, trimesic, diphenic, phenylenediacetic, benzylsuccinic, 1,4-naphthalenedicarboxylic, S-chloro-1,3-benzene-dicarboxylic, tetrachlorophthalic, 1,2-cyclohexanedi-carboxylic, 2,4 pyridinedicarboxylic, 2,5-tetrahydro~
furandicarboxylic, maleic, but-2-enedioic, 1,5-pent 2-enedioic, itaconic, ~ methyleneglutaric, ~-methylene-adipic, ~-methylitaconic, and a,~-dimethylitaconic acid.
The polyesters of the invention having 100 mole percent do~l to about 50 mole percent of alpha-methylene dicarboxylic acid and 0 to about 5Q mole percent of dicarboxylic acid not having an alpha-methylene group are highly responsive to polymerization by actinic radiation even in the presence of oxygen. With a decrease of dicar-boxylic acids having alpha-methylene content below about 50 mole percent, the rate of polymeriza-tion of the poly-ester decreases, so that below about 10-20 mole percent alpha~methylene-containing dicarboxyclic acids, curing on exposure to actinic radiation proceeds very slowly.
The polyesters of the invention contain secondary hydroxyl groups which are formed on reaction of heterocyclic diepoxide with polycarboxylic acid as is shown in Equation II. These hydroxyls can be function-alized by reaction with an acylation group and thereby the polyester can be tailored to desirable properties such as g~' increased solubility in a particular solvent, improved tensile strength and reduced flammability. In this manner, O O
Rl Of formula I is replaced by -C-R3 or -CNHR4.
Exemplary acylation agents from which Rl is derived include acid chlorides such as acetyl chloride, propionyl chloride, valeryl chloride, dodecanoyl chloride, acryloyl chloride, methacryloyl chloride, alpha-chloroacryloyl chloride, crotonoyl chloride, benzoyl chloride, phenyl-acetyl chloride, cinnamoyl chloride and 2,4-dichlorophenyl-acetyl chloride; the corresponding carboxylic acids and anhydrides; other anhydrides include the anhydrides of dicarboxylic acids such as maleic anhydride, succinic anhydride, methylenesuccinic anhydride, phthalic anhydride, and 3-chlorophthalic anhydride; and organic isocyanates such as methyl isocyanate, ethyl isocyanate, n-butyl isocyanate, phenyl isocyanate, 4 t-butyl isocyanate, acryloyloxyethyl isocyanate, methacryloyloxy~
ethyl isocyanate, 4-methacryloyloxybutyl isocyanate, 4-acryloylphenyl isocyanate and 4-vinylphenyl isocyanate.
Preferred acylating agents are the acryloyloxyal~.yl isocyanates in which the alkyl group has 2 to 4 carbon atoms such clS methacryloyloxyethyl isocyanate. Other preferred ac:ylating agents are maleic anhydride and succinic anhydride. The acryloyloxyalkyl isocyanates are preferred for acylation because of the relative ease of reaction with the secondary hydroxyls of the polyester and because they provide an efficient procedure for increasing the ethylenic unsaturation of the polyester. The anhydrides of dicarboxylic acids are preferred acylating agents. When these agents are used to acylate the secondary hydroxyls of the polyester, carboxyl groups are introduced, thereby increasing the solubility of the polyester in aqueous solvents.
By reaction of the secondary hydroxyls of the polyester with ethylenically unsaturated acylation agents, the ethylenic unsaturation of polyesters having a low con-13 ~ 3 ~

tent of backbone alphamethylene groups can be increased. This in-crease, of course, lncreases the rate of curing of the polyester on exposure to a given amount of energy.
Where the polyesters have been prepared using an excess of diepoxyheterocyclic compound, they contain terminal epoxy groups.
These groups can be reacted with nucleophiles to open the epoxide ring and provide terminal ester groups. Where these nucleophiles are ethylenically substituted such as acrylic acid and methacrylic acid, the polyester becomes terminated with these groups.
Suitable ~olym~rs can be described by the formula:

~M~a~ I2 1 ~b R5 R I o Formula V
o=C-~NH-R4C-R ~C~n XA

wherein M is a copolymer un~t derived from one or more monomers (e.g., any free radically polymerizable, ethylenically unsaturated monomer;
R is hydrogen or methyl; O
R2 is selected from a single bond, -R3-, and -C-W-R3- in which R3 is alkylene havIng 1 to 12 carhon atoms, preferably 1 to 6 carbon atoms, and W is -O-, -S- or -NH-;
R4 and R7 are independently selected from a single bond and methyl-ene, or substituted methylene hav~ng 1 to 12 carbon atoms;
R5 and R6 are independently alkyl or cycloalkyl having 1 to 12 carbon atoms, aryl or aralkyl having 6 to l? carbon atoms or R5 and R~ taken together with the carbon to which they are joined form a 5~ or 6-membered carbocyclic ring, or may be H when at least one of R4 and R7 is methylene;
n is 1, 2 or 3;
X is -O-, -NH- or -S-, A is a polymerizable, ethylenically unsatura~ed group selected from (a) -R8-C=CHR10 in which R8 is an alkylene group having 1 to 12 car~on atoms1 an arylene group having 6 to 10 carbon atorns, or an oxyalkylene group, ~ORtp in which R is a lower alkylene group having 2 to 4 carbon atoms and p is 1 to 4; R9 and R10 are independently hydrogen, and alkyl group having 1 to 12 carbon atoms, or an aryl group having 6 to 10 ring positioned carbon atoms wherein aryl is defined as a phenyl or naphthyl moiety optionally having substitution thereon or (b) -R8-WY in which R8 is as defined under the definition for A, W as defined under the definition for R2, and Y is an ethylenically unsaturated group selected from the group including acryloyl, methacryl-oyl, cinnamoyl, maleoyl, fumaroyl, itaconoyl and crotonoyl and is preferably acryloyl or methacryloyl;
a and b are independent whole integer numhers, and b is at least 1, sufficient to provide the polymer with a weight percent of l~ units in the azlactone-containing interpolymer between about O and 90, preferably O and 75.
The polymeric rnaterial on at least one face of the substrate which bears the reflective metal coating may also be a thermoplastic mater~al which is not further curable. Therrnoplastic materials of this type are well known in the art and include vinyl resins, polyesters, polyamides, polyolefinsl polycarbonates, polyacrylates, polyvinyl acetate, styrene/acrylonitrile copolymers, etcO

~3~P~
--l g--Preferably these polymers will have the same maximum loss modulus temperature range described above.
The thermoplastic compositions of the present invention are used in reflective or capacitive information carrying discs, and there is essentially no limitatLon on the types of additives which may be provided to the system where the polymer does not optically interact with the readout system as long as embossing is not prevented as by the inclusions of large dimensions reinforcing materials.
lQ For example, dyes, pigments, sensitizers, coating aids, plasticizers, surface active agents, reinforcing fillers such as diatomaceous earth, metal oxides, glass bubbles, talc, sllica, and other materials may be readily included.
As previously noted, the curable thermoplastic composi tions of the present invention preferably have a maximum loss modulus at temperatures between 30 and 180C. These properties are essential to practice of the present invention to enable flow of the material into the recess of the embossing master and for preventing an undue amount of stress from building up during shaping of the informa tion carrying layer. These properties enable the low temperature manipulation of the information carrying layer to provide a high quality, imperfectlon free information carrying di 5C .
Where the curable polymer is not itself readily curable by radiation, polymerizable initiators or photo-initiators should be included within the composition.
Initiators for free radical systems include such materials as peroxy, azo, and redox systems all of which are well known and are described frequently in the polymerization art. Included among free radical catalysts are the acyloins and their derivatives such as benzoin, benzoin methyl ether, benzoin ethyl etherl benzoin isopropyl ether, benzoin isobutyl ether, and ~-me-thylbenzoin~ Other useful systems include diketones such as benzil and diacetyl, organic sulfides such as diphenyl monosulfide, diphenyl disulfide, decyl phenyl sulfide, and tetramethyl-- ~o -thiuram monosulfide, S-acyl dithiocarbamates, such as S-benzoyl-N,N-dimethyldithiocarbamate, phenones such as acetophenone, ~ -trlbromoacetophenone, a,a-diethoxy-acetophenone, benzophenone, and amino benzophenones, sul~onyl halides such as p-toluene sulfonyl chloride, l-naphthalenesulfonyl chloride, l,3-benzenedisulfonyl chloride, 2,4-dinitrobenzenesulfonyl bromide disulfonyl chloride and p-acetamidobenzenesulfonyl chloride.
Normally such free radical photoinitiators are used in amounts ranging from about 0.01 to 5 percent by weight of the total polymerizable composition. When the initiator is used in excess of 5 percent by weight, little correspondingly improved effect can be expected. Thus addition of such greater quantities are economically unju~-tified. Preferably about 0.25 to 2 percent by weight ofphotoinitiator is used in the polymerizable composition.
Where the polymerizable groups on the thermo-plastic radiation curable polymer are epoxy groups, photoinitiators such as the complex halogenide salts of aromatic diazonium, iodonium, and sulfonium cations are preferred. The salts are disclosed in the art, for example, U.',. Patents Nos. 4,058,401, 4,069,054, and 4,161,478.
The polymerizable materials of the present inven-tion may also contain amounts of non-polymerizable poly-meric additives and polymerizable monomeric materials.
These may be used to readily control the viscosity of the uncured composition as well as the degree of crosslinking in the cured product. Ethylenically unsaturated monomers suitable for saturation with the free radical polymers used in the present invention include methyl methacrylate, ethyl acrylate, 2-ethylhexyl acrylate, chlorohexyl acryl-ate, styrene, 2-chlorostyrene, 2,4-dichlorostyrene, acrylic acid, acrylamide, acrylonitrile, t-butyl acrylate, methyl acrylate, butyl acrylate, 2-(N-butylcarbamyl)ethyl methacrylate and 2 (N-ethylcarbamyl~ethyl methacrylate.
Other diluting monomers that can be incorporated into the composition of the invention include l,4 butylene dimethylacrylate or acryla~e, ethylene dimethacrylate, he~anediol diacrylate or methacrylate, glyceryl diacrylate or methacrylate, glyceryl triacrylate or trimethyl-acrylate, pentaerythritol triacrylate or trimethacrylate,pentaerythritol tetraacrylate or tetramethacrylate, diallyl phthalate, dipentaerythritol pentaacrylate, neopentylglycol triacrylate, 1,3,5-tri(2-methacryoyloxy~
ethyl)-s-triazine, and polyacryloyl-hydantoins such as those described in U.S. Patents 3,808,226, 3,852,302, and U.S. Patent No. 4,249,011.
In copolymerizations wi~h thermoplastic polymers for epoxy functionalities therein, any comonomer kno~n to be copolymeri2able with epoxy groups may be added to the system, preferably with functionality of those groups.
The compositions of the invention as they are coated onto the substrate by such various means as handcoating, knife edge coating, gravure coating, roll coating, etc. are prepared by simply mixing (under "safe"
conditions if the composition is -to be sensitive to visible light) the radiation curable thermoplastic polymer and sensitlzer (when used) the photointiator, and the other desired addenda including solvents. The coated composition is next coated (e.g., by vapor deposition or sputter coating) with a conductive or reflective metal film. The article i5 then embossed with a stamper so as to replicate the desired information carrying pattern on the surface of the disc. After the information carrying surface has been replicated on the disc, a protective and/or insulating layer of material may be coated thereon as is known in the art. This replication may be performed on one or both sides of the disc.
The information is encoded onto the element by deformation or disruption of the metal or non-metallic conductive coating layer. The essentially smooth planar metal layer in the blank is converted into a layer containing a circular or spiral pattern of depressions in -22~

which the approximately vertical walls surrounding the depressions have metal film which has necked to form a thin connection between the original layer and the flat central area of the depression. The walls may also be ree of metal where the embossing has actually caused the metal in the depression to separate from the metal of the original layer~ These two physical characteristics are distinctive indications that the metal coating layer was embossed. The dimensions of the depressions are also critical. The depth of the depression, from the surface metal layer to the bottom of the depression, is between 0.03 to 10 ~m, generally between 0.03 to 5.0 ~m, and preferably between 0.03 and 2.0 ~m. Some readout systems can use depressions having depths in the range of 0.05 to 0.8 ~m or even 0.07 to O.S ~m.
The disc blanks are used in a process according to the present invention in which the blanks are converted to information carrying discs. This process is effected by taking one of the discs of the present invention and embossing it: at a temperature which is usually between 15 and 150 C above the GmaX (Maximum loss modules) of the thermoplasti.c layer and a pressure which may, for example, be between 'i and 100 kg/cm2. The embossing is perormed with a negat:ive stamper if the embossing is to face out-wardly as in Figure IV or with a positive stamper if theembossing is to face the interior as in Figure III. This forms a spiral array or grooves in the thermoplastic base of radiation curable layer, which array bear depressions which vary ln depth or height from the average level of the surface of the radiation curable layer by between 0.03 and 10~0 IJmO When using a metal coated radiation curable layer, the composition would be irradiated to cure it and to retain the shape desired after or before release from the stamper.
The pressing may be done with a platen or with a roll embosser. If a further curable polymeric resin is ~sed, irradiation is pPrformed through the stamper if it is transparent and through the base if the stamper is opaque. Preferably the embossing is usually carried out at temperatures which are at least 15C~ above G" and between 15 and 100 C above the maximum loss modulus.
More preferably i~ is carried out at temperatures between 20 and 70 C above the maximum loss modulusr The pressure during embossing is preferably between 5 and 75 kg/cm2 and more preferably between 10 and 50 kg/cm2.
The information storage discs of the invention are provided with a reflectlve or conductive layer before the introduction of the information into the discs in accordance with well known techniques. Suitable materials for providing the reflective layer are elements which on chemical vapor deposition, electroless plating, electroplating, vapor deposition or sputtering (although the last is not preferred with radiation curable polymers) onto the storage disc which provide a layer having reflection greater than about 10 percent, often greater than 50 percent, preferably greater than 85 percent, at wavelengths of 500nm or greater. Elements which remain nascent or form oxides (e.g., calcium and magnesium~ can be used as Long as the nascent metal or metal oxide coating is re~lective and not significantly changed by air (i e., become volatile or moisture sensitive). It is of course most preferred to use metals or alloys which are not readily oxidized or corroded in any fashion. The reflective or conductive layer can be about 0.2 to 75 nm preferably 0.2 to 60nm in thickness depending on the particular thermoplastic material coated onto the disc substrate and the particular reflective material used.
Suitable elements or oxides for use in the reflective iayer are carbon, magnesium and magnesium oxide, aluminum, silicon, calcium and calcium oxide, titanium, vanadium, chromium~ cobalt, nickel, copper, germanium, molyldenum, rhodium, silver indium, tin, tungsten, iridium, platinum, iron, gold and alloys thereof. Preferable metals are aluminum, chromium, iron, tin, indium, silver, gold, and alloys thereof. The combinations of metals, organic polymers, and additives would of course generally be selected so as to avoid chemical interaction and poor bonding between layers as is known in the art. Conductive layers may be produced by dispersing particles e.g., car~on or metal~ in binders such as organic polymers, and then coating thin films of these materials on the base. High paxticulate bondiny is generally required to achieve good conduct-ivity in such systems~
The metal layer may be coated with an additional thermo-plastic or thermoset resin after embossing to protect the metallayer. The coating may also be applied to the metal layer before embossing if it is thIn enough and it is also embossable. For example, a 0O5 to 50 nm polymeric embossable film over the metal layer is believed to be quite s-uitable during embossing. This film may also be a thermal ox radiation curable ma-terial such as those described with regard to the polymeric layer on the substrate.
If a radiation curable layer is used between a substrate and a metal layer, the metal layer can be of dimensions that will trans-mit a portion of the curing radiat~on (e.g., ultraviolet or e-beam radiation) and reflect a portion of the reading radiation (e.g.
laser light~ This can be achie~ed by the ordinarily skilled artisian. This is ~mportant mainly when a double sided blank is used or where the substrate is opaque.
Preparation The polymer o~ Example 6 of IJnited States Patent No.
4,309,529, which is used ~n some of the following examples, was prepared in the followIng manner:
There were di~ssolved 110.4 g o~ DGDM~I (0 8 mole epoxide equivalency), 52.0 g itaconic acid (0.8 m acid equivalency), 0.05 g 4-methoxyphenol, 0.76 g triethylamine, and 40 ml p-dioxane in a 250 ml three-necked round bottom flask equipped with mechanical stirrer, reflux condenser and CaSO4 drying tube. The reaction flask temper-a-ture was maintained at 100C for 19.25 hours. At this time, chem-ical titration analysis showed that 99% of the epoxide and carboxy-lic acid groups had been consumed. The solvent was removed at reduced pressure to yield a hard, glassy polyester which is soluble in tetrahydrofuran, p-dioxane, cyclohexanone and alcohol/water solutions.
19.28 g of this copolymer were dissolved in 40 ml cyclohex-anone in a 250 ml three-necked round bot-tom flask equipped with a pressure equalizing dropping funnel, reflux condenser, mechanical stirrer and CaSO4 drying tu~e~ The reaction flask was heated to 55C and 7.78 g (0.5 m equi~alent isocyanate) 2-~me-thacryloyloxy) ethyl isocyanate was added dropwise over the course of ten minutes.
The reaction was stl~rred for 3 hours at 55C, cooled to room temper-ature and .he resulting polymer was precipitated from diethyl ether.
Example 1 A solution containing by weight 24.5 parts of the polymer descrIbed in Example 6 of United States Patent No~ 4,309,529, 0.5 parts of a free radical photoinitiator, 39 parts cyclohexanone, and 36 parts 2 methoxyethanol was filtered through a 5Jum filter. The resulting solut~on was coated on 1.75 x 10 4 m polyvinylidene chloride primed polyet~yleneterephthalate film using a wire wound bar. The coated sheets were air dried for 16 hours at 60Cr One of these sheets was vapor coated with 2.7 nm of chromium.
Coating was done by thermal e~aporation in a background pressure of ~;~ - 25 -3.5 10 6 mm Hg.
The resulting metallized embossable sheet was embossed with video information with a metal stamper. A hydraulic press with a pressure of 37 Kg/cm2 was used. The press platens were heated to 77C.
Ater embossing, the sheet separated easily from the stamper. The sheet was cured by passing it five times 25a --~6 ~ P~
at 5 cmjsec under a medium pressure mercury vapor lamps operating at 80 watts/cm. Exposure was through the uncoated side of the sheet. The sheet was then passed under thc lamp five more times at the same speed. This time, the exposure was through the metal coated side of the sheet.
The resulting conductive video disc was given a thin insulating transparent polymeric coating over the metal layer. A plasma polymerizatiQn process was used to apply this insulating layer. This was performed by a diode-type radio frequency (13.56 mH~) sputter deposition unit with a 40 cm diameter cathode at a spacing of 8 cm which was utilized to plasma deposit a 35.5 nm thick methylmethacrylate dielectric spacer layer. The monomer ,eed mixture composed of 0.985 vapor fraction methyl-methacrylate and 0.015 vapor fraction acrylic acid was introduced at a mass flow rate of about 4 x 10-4 g/sec whereas the argon mass flow rate was about 3 x 10-5 g/sec.
A plasma polymerizing power of about 55 Watts (W) was used which corresponds to a power density of about 4.5 kW/m3 and a power flux of about 450 W/m2. The resulting disc displayed an accurate replication of the information on the stamper~, Example 2 A 1.0 x 10~4m substrate comprising about 7.5 x 10~5m of weight polyethyleneterephthalate adhered to an embossable layer of a copolymer of polyethylene glycol and stoichiometric amount of a mixture of terephthalic acid (80%) and isopthalic acid (20% by weight) of about 2.5 x 10~5m was vapor coated with 30 nm of silver. This video disc blank was embossed in a press with a positive stamper for t~n minutes at 120C and 45 Kg/cm2, then cooled to 35C and removed from the master. The information of the stamper was accurately replicated on the disc which could then be used on a reflective laser readout video disc player.

t~

Example 3 A 1 x 10-3 m poly(vinylchloride) substrate was vapor coated with 41 nm of silver. This coating was done by thermal evaporation at a background pressure of 5.0 x 1o~6 mm Hg.
The resulting metallized poly(vinylchloride) (hereinafter PVC) was embossed with video information using a metal stamper. A hydraulic press with a pressure of 15.5 Kg~cm2 was used. The press plat~ns were heated to 160C. After cooling and separation from the stamper, scanning electron micrographs showed the information was replicated into the metalized PVC disc. A disc such as this could then be used on a reflective, laser readout video disc player.

Example 4 A 1 x 10-3 m PVC substrate was vapor caoted with 28 nm of tin. This coating was done by thermal evaporation at a background pressure of 4.0 x 10-6 mm Hg~
The resulting metallized P~JC was embossed with video information using a metal stamper, A hydraulic press with a pressure of 15.5 Kg/cm2 was used The press platens were heated to 160C. After cooling and separa-tion from the stamper, scanning electron micrographs showed the information was replcated into the metalized PVC disc. A disc such as this could then be used on a reflective, laser readout video disc player.

Example S
A substrate and polymer coating as described in Example 1 was used in this example.
One of these sheets was vapor coated with 4.5 nm of chromium. This metal layer was coated with a 40 nm insulating layer as described by the plasma polymerization process in Example 1.
The resulting construction was embossed with video information using a metal stamper. A hydraulic t~
~2~3 press wi~h a pressure of 333 Kg~cm2 was used. The press platells were heated to 75C.
After embossing the sheet was cured, in contact with the stamper, using an 80 watt/cm medium pressure 5 mercury vapor lamp.
After separation of the resultant conductive video disc from the stamper, scanning electron micrographs showed the information had been replicated accurately into its surface. Such a disc would be suitable for playing on a capacitive video disc player.

Example 6 -A 1.0 x 10-3 PVC suhstrate was vapor coated with 4.0 nm of chromium. This coating was done by thermal evaporation at a background pressure of 80 0 x 10-6 mm Hg.
The resulting metallized PVC was embossed with vid~o information using a metal stamper. A hydraulic press with a pressure of 15.5 Kg/cm~2 was used. The press platens were heated to 160C.
AEter cooling and separation from the stamper, a 40.0 nm insulating layer was applied to the metal as described in Example 1.
The conductive video disc was suitable for pay on a capacitive video disc player.

Example 7 A 2.5 x 10-4 m PVC substrate was vapor caoted with 4.7 nm of chromlum. This metal layer was coated with a 40.0 nm insulating layer, as described in Example 1.
The above construction was embossed with video information using a metal stamper. A hydraulic press with a pressure of 222 Kg/cm2 was used. The press platens were heated to 100C and cooled to 50C for removal of the stamper from the press.
Ater separation from the stamper, scanning electron micrographs showed the information had been 3~

replicated accurately into the surface of this conductive video disc. Such a disc would be suitable for playing on a capacitive video disc player.
Example 8 A 1.75 x lQ 4 m thick sheet of polyvinylidene chloride prim-ed polyethyleneterephthalate was coated with 1.0 x 10 5 m of the polymer described in Example 6 of United States Patent No~
4,309,529. The coating and drying procedures of Example 1 were used. ~he coated side of this sheet was vapor coated with 5.0 nm of chromium using a thermal evaporation technique.
A metal video disc stamper was used to thermally emboss this premetallized sheet. ~ hydraulic press operatIng at 37 kg/cm2 was used. The press platens were heated to 65C. After embossing, the radiation curable polymer was cured by exposure to W radiation from an 80 watt medium press~ure mercury vapor lamp.
Scanning electron microscopy of this video disc indicated good replication of the video disc stamper. The direct current resistance of the disc surface was found -to be 4300 ohms per square.
Example 9 A 1.75 x 10 4 m thick sheet of polyvinylidene chloride prim-ed polyethylene~tereph-th~latewas coated with 1~0 x 10 5 m of the polymer described in Example 6 of United States Patent No. 4,309,529 using the procedures of Example 1. The coated side of this sheet was vapor coated with 6.0 nm of aluminum using a thermal evaporation process.
A metal video disc stamper was used to thermally emboss this premetallized sheet~ A hydraulic press operating at 15 kg/cm2 was used, The press platens were heated to 60C. A~ter embossing, the radiation curabl e polymer was used by exposure to VV radiation.

- 29a --30 ~ P~
Scanning electron microscopy o the resulting video disc showed faithful reproduction of the submicron - details of the metal stamper. The reflectivity of the surface of the replica, measured at 633 nm was 17%.

Claims (21)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A coded information carrying structure capable of being electronically decoded comprising:
(1) a base, (2) a first layer of an electrically conductive or electro-magnetic radiation reflective layer adhered to at least one surface of said base, said layer having coded information in the form of depressions in said layer having been vertically displaced a dis-tance of from 0.03 to 10.0 micrometers, with said first layer having ruptures or necking on the sides of the depressions, and (3) an insulating or transparent protective layer over said first layer.

2. The structure of claim 1 wherein said protective layer is not of uniform thickness with respect to thickness measured from the surface of the protective layer to non-displaced areas of said electrically conductive or electromagnetic radiator reflective layer and said vertically displaced areas.

3. The structure of claim 2 wherein said vertically displaced areas are discrete areas of said first layer.

4. The structure of claim 2 wherein said first layer is a metal layer.

5. The structure of claim 1 wherein said structure is in the form of a disc.

6. The substrate of claim 5 wherein said base comprises a sub-strate wherein at least the surface of said base to which said first layer is adhered is a crosslinked polymer.

7. The structure of claim 5 wherein said first layer has disrupted or necked vertical regions around said vertically displaced areas.

8. The structure of claim 7 wherein said ver-tically displaced areas form a spiral array of protrusions and/or depressions having an average variation in height or depth from the average surface level of the non-dis-placed surface of said first layer of from 0.03 to 10.0 nm.

9. The structure of claim 5 wherein said metal layer has a thickness of from 0.2 to 200 nm.

10. The structure of claims 7 and 8 wherein said metal layer has a thickness of from 0.2 to 75 nm.

11. The structure of claim 2 wherein said base has on opposite surfaces both 1) a first layer of an electrically conductive or electromagnetic radiation reflective layer adhered to at least one surface of said base, said layer having coded information in the form of areas of said layer having been vertically displaced, and 2) a protective layer over said first layer which is not of uniform thickness with respect to thickness measured from the surface of the protective layer to non-displaced areas of said electrically conductive or electromagnetic radiation reflective layer and said vertically displaced areas.

12. A composite structure comprising two struc-tures according to claim 2 which are adhered so that the vertically displaced areas of each extend away from each other.

13. A composite structure comprising two structures according to claim 2 which are adhered so that the vertically displaced areas of each extend towards each other.

14. A two-sided information carrying structure comprising two bases, each base having a first layer of an electrically conductive or electromagnetic radiation reflective layer adhered to one sur-face of each base, said first layers having coded information in the form of depressions in said layer having been vertically dis-placed a distance of from 0.03 to 10.0 micrometers, with the first layers having ruptures or necking on the sides of the depressions, said first layers being adhered together.

15. The structure of claims 7 or 8, wherein said protective layer is an insulating organic polymeric layer of from 1 to 100 nm.

16. A process for forming an information bearing article which comprises embossing coded information which may be electronically decoded onto a multilayered article comprising:
(a) a base having at least one thermoplastic surface and adhered onto said surface, (b) an electrically conductive layer or electromagnetic radiation reflective layer to form a coded information bearing surface on said layer, said coded information being formed by the vertical displacement of areas of said layer to a depth of 0.03 to 10.0 micrometers with said layer having ruptures or necking on the side of said depression.

17. The process of claim 16 wherein said layer is a metal layer having a thickness of from 0.2 to 75 nm.

18. The process of claim 16 wherein said base comprises a sub-strate having as said at least one thermoplastic surface a layer of a thermoplastic, radiation curable, polymeric resin, and wherein said resin is irradiated to cure said resin during embossing and before said multilayered article is removed from the mold used during embossing.

19. A multilayered article for use in the manufacture of coded information bearing surfaces which may be electronically decoded comprising:
a) a base having at least one surface of which is a layer of a thermoplastic, radiation curable polymeric resin, b) an embossable electrically conductive or electromagnetic radiation reflective layer over said at least one surface.

20. The multilayered article of claim 19 wherein said embossable layer is a metal layer having a thickness between 0.2 and 75 nm.

21. The multilayered article of claim 20 wherein said layer of polymeric resin exhibits a maximum loss modulus which appears between 30 and 180°C.