WO2012031054A1

WO2012031054A1 - Thermoplastic composition having improved melt flowability

Info

Publication number: WO2012031054A1
Application number: PCT/US2011/050110
Authority: WO
Inventors: Tengjiao Hu; Lei YING; Hua Jiao
Original assignee: E. I. Du Pont De Nemours And Company
Priority date: 2010-09-01
Filing date: 2011-09-01
Publication date: 2012-03-08
Also published as: CN102382438A

Abstract

Disclosed are thermoplastic compositions comprising a polycarbonate, a polyester, an impact modifier, a melt viscosity modifier, and optionally other additives. A good balance of flowability and mechanical properties is obtained by controlling the amount of the melt viscosity modifier. The compositions and the molded article of this invention are suitable to be used as electric/electronic devices parts, automotive parts, machine parts, etc.

Description

THERMOPLASTIC COMPOSITION HAVING IMPROVED MELT

FLOWABILITY

FIELD OF THE INVENTION

This invention relates to the field of polymeric compositions, particularly to certain thermoplastic polymeric compositions exhibiting improved melt flowability as well as good mechanical properties, methods of preparation and applications of said thermoplastic polymeric compositions.

BACKGROUND OF THE INVENTION

Thermoplastic compositions containing polycarbonates (PC), polyesters, and elastomeric impact modifiers are known and available commercially. The impact modifiers thus suitable include acrylonitrile-butadiene-styrene copolymer (ABS) or methylacrylate-butadiene-styrene copolymer (MBS).

A U.S. Patent, US5, 674,928 discloses a thermoplastic resin composition containing a polyester resin, a polycarbonate resin and a graft copolymer containing a rubbery substrate and a rigid superstrate. MBS graft copolymers are among the disclosed graft copolymer.

A Japanese patent publication, JP2001-031860 discloses a composition containing polycarbonate, a mixture of polyethylene terephthalate (PET) and polybutylene terephthalate (PBT) and a graft elastomer having a core-shell structure. The composition said to exhibit high impact strength, hydrolytic stability and chemical resistance.

A PCT patent publication, WO2008/069935 discloses a blend of

polycarbonate, polyalkylene terephthalate, and an impact modifier that contains a MBS core-shell polymer. The composition said to exhibit improved surface quality and toughness at low temperature.

These thermoplastic compositions (also known as PC/polyester alloy) are employed in making injection molded parts, films, blow-molded goods, pultruded sheets etc. These articles are used in automotive, electrical and electronic applications. The mechanical strength, electrical insulation and easy

processability are some of the key characteristics of PC/polyester alloy, which enable their use in these applications. The current industrial trend is towards fabrication of parts with complicated and fine designs with small flow cross- sectional areas, where flowability of conventional PC/polyester alloy has been found inadequate.

Incorporation of polyhydric alcohols is among the various approaches known to reduce the melt viscosity of polymers such as polyamides and/or polyester, . It has the potential to provide the advantage of not having the need to modify the polymeric compositions.

A European patent publication, EP0682057A1 describes the flow enhancement of polyamide and polyester compositions with retention of mechanical properties by using dendrimeric additives. However, dendrimeric compounds in general are prepared in several separate steps from basic raw materials and are expensive.

A European patent publication, EP 1041109 A2 describes the flow enhancement of glass fiber filled polyamide compositions by using a polyhydric alcohol having melting point between 150-280°C, for example, pentaerythritol or dipentaerythritol. In polyamide compositions, both pentaerythritol and dipentaerythritol showed identical flow enhancing effects.

A Japanese patent publication, JP 10310690 discloses the use of 0.1-5% of pentaerythritol or l,l,l-tris(hydroxymethyl)ethane and 1,1,1- tri(hydroxymethyl)propane in a polybutylene terephthlate (PBT) for enhancing melt flow. The effect of these flow enhancing additives on other properties of the matrix resin and the effect of other ingredients in the formulations were not disclosed.

A European patent publication, EP0272417 A2 describes a composition comprising aromatic polycarbonate and polyester and 0.01-5% of a polyol. The polyol acts as anti-yellowing agent. The effect of the polyol on other properties were not disclosed. Further, no impact modifier was mentioned in the disclosure as additive to the composition.

A U.S. patent publication, US2007/0049667 discloses the flow

enhancement of a polyester compositions by using of 0.05-2% of a hydroxyl compound (for example, pentaerythritol and trishydroxymethyl aminoethane) comprising 0.1-25% of an acrylic impact modifier and about 0.1-50% of a reinforcing filler. Said polyester may further comprise other thermoplastic including polycarbonate.

The present invention provides improved melt viscosity of thermoplastic polymer compositions without sacrificing mechanical properties.

SUMMARY OF THE INVENTION

This invention is directed to a thermoplastic composition comprising:

(a) about 60-85% of an aromatic polycarbonate,

(b) about 5-30% of a polytrimethylene terephthalate,

(c) about 3-15% of an impact modifier, and

(d) about 0.01-0.5%) of a melt flow modifier;

said percents being relative to the total weight of the composition.

In one embodiment, the thermoplastic composition of the present invention is substantially free of reinforcing filler.

In one embodiment, in the thermoplastic composition of the present invention, the aromatic polycarbonate is based on bisphenol A.

In one embodiment, in the thermoplastic composition of the present invention, the aromatic polycarbonate has a melt mass flow rate of from about 5- 20 g per 10 min.

In one embodiment, in the thermoplastic composition of the present invention, the polytrimethylene terephthalate has an intrinsic viscosity of about 0.8 to 1.2.

In one embodiment, in the thermoplastic composition of the present invention, the impact modifier is a core-shell type copolymer comprising a shell of polymethyl methacrylate.

In one embodiment, in the thermoplastic composition of the present invention, the rubber core of the impact modifier has a glass transition temperature from -80°C to -20°C.

In one embodiment, in the thermoplastic composition of the present invention, the rubber core of the impact modifier is butadiene rubber or silicone rubber.

In one embodiment, in the thermoplastic composition of the present invention, the melt flow modifier is a polyol selected from 2,2-dimethyl-l,3- propanediol, glycerol, l,l,l-tris(hydroxymethyl)ethane,

l,l,l-tris(hydroxymethyl)propane, pentaerythritol, xylitol, sorbitol,

dipentaerythritol and tripentaerythritol.

In one embodiment, in the thermoplastic composition of the present invention, the melt flow modifier is l,l,l-tris(hydroxymethyl)ethane,

pentaerythritol, dipentaerythritol or tripentaerythritol..

In one embodiment, the thermoplastic composition of the present invention further comprises at least one additive selected from a group consisting of antioxidants, thermal stabilizers, ultraviolet light stabilizers, colorants including dyes and pigments, lubricants, hydrolysis resistants, demolding agents and flame retardants.

This invention also directed to a molded article comprising or produced from the compositions disclosed above. This invention is also directed to the use of the molded article as electric/electronic devices parts, automotive parts, machine parts, etc.

Various other features, aspects, and advantages of the present invention will become more apparent with reference to the following description, examples, and appended claims.

DETAILS OF THE INVENTION

All publications, patent applications, patents and other references mentioned herein, if not otherwise indicated, are explicitly incorporated by reference herein in their entirety for all purposes as if fully set forth.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In case of conflict, the present specification, including definitions, will control.

Except where expressly noted, trademarks are shown in upper case.

Unless stated otherwise, all percentages, parts, ratios, etc., are by weight.

When an amount, concentration, or other value or parameter is given as either a range, preferred range or a list of upper preferable values and lower preferable values, this is to be understood as specifically disclosing all ranges formed from any pair of any upper range limit or preferred value and any lower range limit or preferred value, regardless of whether ranges are separately disclosed. Where a range of numerical values is recited herein, unless otherwise stated, the range is intended to include the endpoints thereof, and all integers and fractions within the range.

As used herein, the term "produced from" is synonymous to "comprising". As used herein, the terms "comprises," "comprising," "includes," "including," "has," "having," "contains" or "containing," or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus. Further, unless expressly stated to the contrary, "or" refers to an inclusive "or" and not to an exclusive "or". For example, a condition A "or" B is satisfied by any one of the following: A is true (or present) and B is false (or not present), A is false (or not present) and B is true (or present), and both A and B are true (or present).

Also, the indefinite articles "a" and "an" preceding an element or component of the invention are intended to be nonrestrictive regarding the number of instances (i.e. occurrences) of the element or component. Therefore "a" or "an" should be read to include one or at least one, and the singular word form of the element or component also includes the plural unless the number is obviously meant to be singular.

As used herein, the term "substantially free of a component means that the amount of the component is not higher than 0.5%.

The materials, methods, and examples herein are illustrative only and, except as specifically stated, are not intended to be limiting. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, suitable methods and materials are described herein.

It is known that flow promotion in polyesters by use of polyhydric alcohols poses special challenges owing to the propensity of polyesters to undergo transesterification with the hydroxy groups which will cause degradation of the polyester with a likelihood of undesirable changes in the mechanical properties. The challenge therefore is to find an effective amount of the polyhydric alcohols to achieve high flowability without affecting their mechanical strength in polyester compositions.

It's therefore surprising to find the improved melt viscosity without sacrificing mechanical properties of the present inventive compositions without reinforcing filler (such as glass fiber) disclosed herein.

The invention is described in detail hereinunder. First mentioned are the components (a) to (d) constituting the thermoplastic composition of the invention.

(a) Aromatic polycarbonate (PC)

The aromatic polycarbonates used in this thermoplastic composition are derived from diphenols and carbonate precursors in a solution method or in a melt method, such as those as produced through reaction of a diphenol and phosgene or through interesterification of a diphenol and a diphenyl carbonate.

Various diphenols are usable, including, for example,

2,2-bis(4-hydroxyphenyl)propane (i.e. bisphenol A), bis(4- hydroxyphenyl)methane, 1,1 -bis (4-hydroxyphenyl)ethane, 2,2-bis(4-hydroxy- 3,5-dimethylphenyl)propane, 4,4'-dihydroxydiphenyl, bis(4- hydroxyphenyl)cycloalkanes, bis(4-hydroxyphenyl)oxide, bis(4- hydroxyphenyl)sulfide, bis(4-hydroxyphenyl)sulfone, bis(4-hydroxyphenyl) sulfoxide, bis(4-hydroxyphenyl)ether, bis(4-hydroxyphenyl)ketone, etc. Other diphenols such as hydroquinone, resorcinol, catechol and the like are also usable in the invention. The diphenols mentioned herein may be used either singly or as combined.

The carbonate precursors for use in the invention include, for example, carbonyl halides, carbonyl esters, haloformates,, phosgene, diphenol

dihaloformates, diphenyl carbonate, dimethyl carbonate, and diethyl carbonate.

Branched polycarbonates are prepared by adding a branching agent during polymerization. These branching agents are well known and may comprise polyfunctional groups organic compounds containing at least three functional groups which may be hydroxyl, carboxyl, carboxylic anhydride, haloformyl and mixtures thereof. Specific examples include trimellitic acid, trimellitic anhydride, trimellitic trichloride, tris-p-hydroxy phenyl ethane, isatin-bis-phenol, tris-phenol TC (l,3,5-tris((p-hydroxyphenyl)-isopropyl)benzene), tris-phenol PA (4(4(1,1- bis(p-hydroxyphenyl)-ethyl)alpha, alpha-dimethyl benzyl)phenol), 4-chloroformyl phthalic anhydride, trimesic acid and benzophenone tetracarboxylic acid. The branching agent may be added at a level of about 0.05-2.0 weight percent.

Branching agents and procedures for making branched polycarbonates are described in U.S. Patent Nos. 3,635,895; 4,001,184; and 4,204,047.

Various types of different polycarbonate resins may be mixed to give mixed polycarbonate resins for use in the invention. For example, polycarbonates may be branched polycarbonates or unbranched polycarbonates, copolymers thereof, and mixtures thereof. In an alternative embodiment, the polycarbonate resin is a blend of two or more polycarbonate resins.

Of note are aromatic polycarbonates based on bisphenol A. In another embodiment, the aromatic polycarbonate has a melt mass flow rate of about 5-20 g per 10 min as measured at 300°C under a load of 1.2 Kg according to ISOl 133, preferably from about 8-12 g per 10 min .

Suitable types of polycarbonates can be selected from commercial brands such as MAKROLON™ from Bayer, LEXAN^® from S ABIC Innovative Plastics, PANLITE^® from Teijin, XANTAR^® from DSM, IUPILON^® from Mitsubishi, and CALIBER^® from Dow. The present list is indicative and not exhaustive.

The level of polycarbonate (a) employed in the thermoplastic composition of the present invention ranges from about 60 wt. % to about 85 wt. % of the total weight of the thermoplastic composition, preferably from about 65% to about 80% of the total weight of the thermoplastic composition, more preferably from about 68% to about 75% of the total weight of the thermoplastic composition.

(b) Polytrimethylene terephthalate

Polytrimethylene terephthalate (PTT) serving as the component (b) of the present thermoplastic composition is a polyester. Polyester polymers are well known to one skilled in the art and may include any condensation polymerization products derived from, by esterification or transesterification, an alcohol and a dicarboxylic acid including ester thereof.

Polytrimethylene terephthalate (PTT) may be prepared by the condensation polymerization of 1,3-propanediol and terephthalic acid. Alternatively, polytrimethylene terephthalate may also be prepared from 1,3-propanediol and dimethylterephthalate. The 1,3-propanediol for use in making the PTT is preferably obtained biochemically from a renewable source ("biologically- derived" 1,3-propanediol).

Because polyesters and processes for making them are well known to one skilled in the art, further description is omitted herein for the interest of brevity.

Intrinsic viscosity (IV) is a measure of the molecular weight of a polymer and may be measured according to ASTM D4603-96. For example, a Viscotek Forced Flow Viscometer model Y-900 may be used. In the method, the polymers are dissolved in a phenol/tetrachloroethane (60/40 wt%) solution at a 0.5% (wt/vol) concentration and tested at 25°C. Intrinsic viscosity typically increases with increasing polymer molecular weight, but is also dependent on the type of macromolecule, its shape or conformation, and the solvent it is measured in.

Commercially available polytrimethylene terephthalates include without limitation SORONA^® from DuPont and CORTERRA^® from Shell Chemicals.

The level of polytrimethylene terephthalate (b) employed in the

thermoplastic composition of the present invention ranges from about 5% to about 30 % of the total weight of the thermoplastic composition, preferably from about 10% to about 25% of the total weight of the thermoplastic composition, more preferably from about 15% to about 20% of the total weight of the thermoplastic composition.

(c) Impact modifier

The component (c) to be added in the thermoplastic composition of the invention is an impact modifier. The impact modifier may be at least one selected from the group consisting of an olefin copolymer, a core-shell graft copolymer and a mixture thereof.

Examples of the olefin copolymer that can be used in the present invention may include without limitation ethylene/propylene rubber, isoprene rubber, ethylene/octene rubber, ethylene -propylene-diene terpolymer (EPDM), and the like, and combinations thereof.

The olefin copolymer may be grafted with about 0.1% to about 5% by weight of at least one reactive functional group selected from maleic anhydride, glycidylmethacrylate, oxazoline, and the like, and combinations thereof, to form a core-shell graft copolymer. Grafting the reactive functional group into the olefin copolymer can be readily practiced by a person having ordinary skill in the art to which the invention pertains.

Exemplary core-shell graft copolymers useful in the present invention can be prepared by polymerizing at least one rubber monomer, such as a diene rubber monomer, an acrylate rubber monomer, a silicone rubber monomer, or the like, or a combination thereof, to form a rubber polymer, and grafting the resulting rubber polymer with at least one monomer to be the shell, such as graftable styrene, a- methylstyrene, halogen- or alkyl (such as Ci-C₈ alkyl)-substituted styrene, acrylonitrile, methacrylonitrile, Ci-Cs methacrylic acid alkyl ester, Ci-Cs acrylic acid alkyl ester, maleic anhydride, an unsaturated compound such as C1-C4 alkyl or phenyl nucleus-substituted maleimide, or the like, or a combination thereof. The content of the rubber can range from about 30% to about 90% by weight.

The Ci-Cs methacrylic acid alkyl ester or the Ci-Cs acrylic acid alkyl ester is an ester of methacrylic acid or acrylic acid, and is prepared from monohydric alcohol containing 1 to 8 carbon atoms. Examples of these esters may include without limitation methacrylic acid methyl ester, methacrylic acid ethyl ester, methacrylic acid propyl ester, and the like, and combinations thereof.

Examples of the diene rubber may include without limitation butadiene rubber, acrylic rubber, ethylene/propylene rubber, styrene/butadiene rubber, acrylonitrile/butadiene rubber, isoprene rubber, ethylene-propylene-diene terpolymer (EPDM), and the like, and combinations thereof.

The acrylate rubber may include an acrylate monomer such as but not limited to methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, 2- ethylhexyl acrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, and the like, and combinations thereof. Examples of suitable curing agents used in preparing the copolymer may include without limitation ethylene glycol dimethacrylate, propylene glycol dimethacrylate, 1 ,3-butylene glycol dimethacrylate, 1 ,4-butylene glycol dimethacrylate, allyl methacrylate, triallyl cyanurate, and the like, and combinations thereof.

The silicone rubber can be prepared from cyclosiloxane. Examples of the cyclosiloxane may include without limitation hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane,

dodecamethylcyclohexasiloxane, trimethyltriphenylcyclotrisiloxane,

tetramethyltetraphenylcyclotetrasiloxane, octaphenylcyclotetrasiloxane, and the like, and combinations thereof. The silicone rubber can be prepared from at least one of the above-mentioned siloxane materials, using a curing agent. Examples of suitable curing agents may include without limitation trimethoxymethylsilane, triethoxyphenylsilane, tetramethoxysilane, tetraethoxysilane, and the like, and combinations thereof.

In one embodiment, in the thermoplastic composition of the present invention, the rubber core of the impact modifier is a butadiene rubber or a silicone rubber.

The preparation of core-shell polymers and their use as impact modifiers are described in U.S. Patent Nos. 3,864,428 and 4,264,487.

Suitable impact modifiers may be mixtures comprising core shell impact modifiers made via emulsion polymerization using alkyl acrylate, styrene and butadiene. These include, for example, methylmethacrylate-butadiene-styrene (MBS) and methylmethacrylate-butylacrylate core shell rubbers. Especially preferred grafted polymers are the core-shell polymers available from Rohm & Haas under the trade name PARALOID^®, including, for example, PARALOID^® EXL3691 and PARALOID^® EXL3330, EXL3300 and EXL2300 as well as ClearStrength^® E920 from Arkema.

The impact modifiers can be of various particle sizes. The preferred range is from 50-800 nm, however larger particles, or mixtures of small and large particles, may also be used.

Preferred impact modifiers having a rubber core with a Tg (glass transition temperature) from -80°C to -20°C, preferably between about -60° to about -30°C, which comprise polyalkylacrylates or polyolefms grafted with

polymethylmethacrylate or styrene-acrylonitrile copolymer. In one embodiment, in the thermoplastic composition of the present invention, the rubber core of the impact modifier has a glass transition

temperature from -80°C to -20°C.

A useful amount of impact modifier (c) is about 3% to about 15% of the total weight of the thermoplastic composition, preferably about 7% to about 11% of the total weight of the thermoplastic composition.

When the content of the impact modifier is lower than about 3 weight percent, this may result in insignificant impact modifying effects of the thermoplastic composition. On the other hand, when the content of the impact modifier is higher than about 15 weight percent, this may result in deterioration of mechanical strength (such as tensile strength, flexural modulus, and the like) of the thermoplastic composition.

(d) Melt flow modifier

The component (d) to be in the thermoplastic composition of the invention is a melt flow modifier. The melt flow modifier used in the thermoplastic composition of the present invention is a polyhydric alcohol (i.e. polyol).

Examples of the melt flow modifier that can be used in the present invention may b includ without limitation polyols selected from 2,2-dimethyl-l,3- propanediol, glycerol, l,l,l-tris(hydroxymethyl)ethane,

1,1,1 -tris(hydroxymethyl)propane, pentaerythritol, xylitol, sorbitol,

dipentaerythritol, and tripentaerythritol.

1,1,1 -tris(hydroxymethyl)propane, pentaerythritol, xylitol, sorbitol,

dipentaerythritol and tripentaerythritol.

In one embodiment, in the thermoplastic composition of the present invention, the melt flow modifier is selected from

l,l,l-tris(hydroxymethyl)ethane, pentaerythritol, dipentaerythritol and tripentaerythritol.

A useful amount of melt flow modifier is about 0.01-0.5 weight %>, preferably about 0.1-0.4 weight %>, wherein the weight percentages are based on the total weight of the thermoplastic composition. When the amount of the melt flow modifier is about 0.1 weight %, flow improvement can be observed with good mechanical properties of the thermoplastic composition. When the amount of the melt flow modifier exceeds 0.5 weight %, the mechanical properties of the thermoplastic composition are adversely affected.

Other Additives

The thermoplastic composition of the present invention may further comprise optional additives commonly used and well known in the polymer art. Examples of additives include without limitation antioxidants, thermal stabilizers, ultraviolet light stabilizers, colorants including dyes and pigments, lubricants, hydrolysis resistants, demolding agents, and flame retardants. These additive(s) may be present in the compositions in quantities that are generally from 0.01 to 15 weight %, preferably from 0.01 to 10 weight %, so long as they do not detract from the basic and novel characteristics of the thermoplastic composition and do not significantly adversely affect the performance of the thermoplastic

composition. Reinforcing fillers such as carbon fibers, short glass fibers, long glass fibers, mica, talc, wollastonite, clay, fibrillating tetrafluoroethylene are generally well known in the art, as are their methods of manufacture. Of note is that the thermoplastic composition of the present invention is substantially free of reinforcing filler. The term "substantially free of reinforcing filler" means that the amount of the reinforcing filler in the thermoplastic composition of the present invention is not higher than 0.5 wt% , preferably not higher than 0.1 wt% relative to the total weight of the thermoplastic composition.

The thermoplastic composition of the invention may be formed by techniques known in the art. The ingredients and optional additives are typically in powder or granular form, and extruded as a blend, and/or cutting into pellets or other suitable shapes. The ingredients may be combined in any manner, e.g., by dry mixing or by mixing in the melted state in an extruder, or in other mixers. For example, one embodiment comprises melt blending the ingredients in powder or granular form, extruding the blend and comminuting into pellets or other suitable shapes. Also included is dry mixing the ingredients, followed by mixing in the melted state in an extruder. Molded articles may be produced from a thermoplastic composition of the present invention disclosed above, by virtually any method of extrusion

processing or thermoforming known to those skilled in this art. For example, a melt extrusion process such as injection molding, coinjection molding,

compression molding, overmolding and profile extrusion may be used. As such, the articles may be injection molded, compression molded, profile extruded or the like. Of note is a molded article comprising or produced from the compositions disclosed above.

The thermoplastic composition of the present invention can be used for molding of various products and is particularly suitable for use in automotive parts, and for manufacturing electric and electronic appliances such as housings of TV sets, computers, mobile communication equipment and office automation equipment. The present thermoplastic compositions can also be made into films and sheets.

EXAMPLES

The Examples are illustrative and are not to be construed as to unduly limit the scope of the invention. Examples of the invention are designated by Ex. 1-16 and the particularly desirable features of this invention may be seen by comparing the characteristics of Ex. 1 to 16 with the comparative examples A and B. The examples were all prepared and tested in a similar manner.

The ingredients used in the examples are given in Table 1.

Table 1

Abbreviation Material

PC PANLITE L-1250 Y, a bisphenol A-type aromatic polycarbonate having a melt mass flow rate of 8 g per 10 min at 300°C under a load of 1.2Kg, produced by Teijin Chemicals Ltd., Japan.

PTT a polytrimethylene terephthalate homopolymer with melt temperature of

228°C, Tg of about 45°C and intrinsic viscosity (IV) of 0.99, obtained from DuPont under the trade name of SORONA^®.

MBS a methacrylate-butadiene-styrene copolymer, an impact modifier having a core-shell structure, obtained from Arkema under Clearstrength^® E-920.

Pentaerythritol 2, 2-bis(hydroxymethyl)- 1,3 -propanediol (CAS number 115-77-5), a polyhydric alcohol as a melt flow modifier purchased from SCRC (S¾j).

1,1,1 -tris(hydroxymethyl)- 2-(hydroxymethyl)-2-methyl- 1,3 -propanediol (CAS number 77-85-0), a ethane polyhydric alcohol as a melt flow modifier purchased from SCRC (S¾j).

Xylitol (CAS number 87-99-0), a polyhydric alcohol as a melt flow modifier purchased from SCRC (S!§). Abbreviation Material

Sorbitol D-Glucitol (CAS number 50-70-4), a polyhydric alcohol as a melt flow modifier purchased from SCRC (S¾j).

Dipentaerythritol 2,2'-[oxybis(methylene)]bis[2-(hydroxymethyl)- 1 ,3 -propanediol (CAS number 126-58-9), a polyhydric alcohol as a melt flow modifier purchased from SCRC (S!§).

Tripentaerythritol 2,2-bis[[3 -hydroxy-2,2-bis(hydroxymethyl)propoxy]methyl] -1,3- propanediol (CAS number 78-24-0), a polyhydric alcohol as a melt flow modifier purchased from SCRC (S¾j).

PETS Pentaerythritol tetrastearate (CAS number 115-83-3), a mold releasing agent purchased from TCI under catalog number P0739.

IRGAFOS 168 a trisarylphosphite thermal stabilizer (CAS number 31570-04-4),

obtained from Ciba Specialty Chemicals.

IRGANC r 1010 Tetrakis(methylene-3-(3,5-di-i-butyl-4- hydroxyphneyl)propionate)methane (CAS number 6683-19-8), a phenolic based antioxidant, obtained from Ciba Specialty Chemicals.

Detailed Procedure

a) Compounding: The ingredients of each example were mixed together and then fed to a twin screw extruder to obtain the corresponding thermoplastic

composition as pellets. The temperature of the extruder was set to be

200/240/240/240/250/250/255/255/255/255°C for the extruder of 10 heating block configuration. The die temperature was 255°C and the screw speed was at 350 rpm with a throughput of 22 Kg/hour.

b) Molding: The extruded pellets were dried to a moisture level of less than 40 ppm prior to molding. For mechanical property tests, multipurpose test specimen according to IS03167 were molded on a Sumitomo 100 Ton molding machine with a screw diameter of 32 mm and 5 mm for the nozzle diameter. The barrel temperature was set to be 255°C and mold temperature was 60°C. The

multipurpose test specimen has the basic shape of a tensile dog bone, 150 mm long, with the center section 10 mm wide by 4 mm thick by 80 mm long.

Testing Methods

Spiral flow was measured in a Sumitomo 100 Ton molding machine with a spiral mold. The flow length (in cm) in the mold was measured under the given test conditions. Melt temperature, mold temperature, gauge of spiral flow, and boost pressure were 255°C, 70°C, 2 mm, and 80 Mpa, respectively. The first 10- 15 parts were thrown away until constant flow length has been reached. The reported values were average of 5 parts.

The flexural modulus (0.05%-0.25%) and the flexural stress at 3.5% strain were measured according to ISO 178:2001(E). The mechanical properties, such as tensile stress at break, and tensile strain at break were measured according to ISO 527: 1993(E).

Izod impact (notched, type A) was measured on a Resil Impactor at room temperature according to ISO180:2000(E).

Compositions of the examples and comparative examples as well as the evaluation results are shown in Tables 2, 3 and 4.

Table 2. Effective Amount of Melt Flow Modifier

Unit Comp. Ex.A Ex. 1 Ex. 2 Ex. 3 Comp. Ex.B

Component (bv wei-iht)

PC (80 parts) % 71.8 71.8 71.7 71.6 71.3

PTT (20 parts) % 18.0 17.9 17.9 17.9 17.8

MBS (10 parts) % 9.0 9.0 9.0 9.0 8.9

Pentaerythritol % 0 0.09 0.18 0.36 0.71

IRGAFOS^® 168 % 0.45 0.45 0.45 0.45 0.45

IRGANOX^® 1010 % 0.36 0.36 0.36 0.36 0.36

PETS % 0.45 0.45 0.45 0.45 0.46

Composition (Total) % 100 100 100 100 100

Properties

Spiral flow cm 11.5 14.6 20.5 28.1 49.2

Flex modulus MPa 2176 2097 2097 2141 2278

Flex stress MPa 67.2 68.0 68.3 69.9 74.6

Tensile stress at break MPa 55.1 49.0 43.0 41.3 40.2

Tensile strain at break % 103 75 71 39 10

Izod impact KJ/m² 56 50 42 35 2

From the results of Table 2, the following are evident.

From the comparison between the working examples 1 to 3 and the

comparative examples A and B, it can be seen that the thermoplastic compositions respectively obtained by mixing 0.1, 0.2 and 0.4 parts (i.e. from 0.01 to 0.5

weight%) of (d) a melt flow modifier (i.e. pentaerythritol) with 80 parts by weight of (a) an aromatic polycarbonate, 20 parts of (b) a PTT and 10 parts of (c) an impact modifier are excellent in flowability and mechanical properties.

Further as shown in comparative example B, it can be seen that in the case where the added amount of (d) a melt flow modifier (i.e. pentaerythritol) was more than 0.5 weight %, the flowability was improved greatly, however, the mechanical properties (tensile strain at break and Izod impact) declined significantly.

From the comparison between the working examples 4 to 10 of Table 3 , it

can be seen that thermoplastic compositions of the present invention obtained by

mixing 0.18 weight% of (d) a melt flow modifier (i.e. pentaerythritol) with

components (a) an aromatic polycarbonate, (b) a PTT and (c) an impact modifier

at various weight% ratios also showed excellent balance between the flowability

and mechanical properties. Noted that compositions having the same amount of

melt flow modifier (0.18 weight%), the resulting spiral flow data increased as the

amount of the aromatic polycarbonate decreased that is due to the poorer intrinsic flowability of the aromatic polycarbonate compared to that of the PTT.

Table 3. Examples of Components (a), (b) and (c) at various ratios

Unit Ex. 4 Ex. 5 Ex. 6 Ex. 7 Ex. 8 Ex. 9 Ex. 10

Component (by weight)

PC % 84.3 83.8 78.8 73.9 70.4 64.0 63.4

PTT % 6.8 9.9 9.9 17.2 17.2 24.6 27.7

MBS % 7.4 4.9 9.9 7.4 10.9 9.9 7.4

Pentaerythritol % 0.18 0.18 0.18 0.18 0.18 0.18 0.18

IRGAFOS^® 168 % 0.44 0.44 0.44 0.44 0.44 0.44 0.44

IRGANOX^® 1010 % 0.35 0.35 0.35 0.35 0.35 0.35 0.35

PETS % 0.49 0.49 0.49 0.49 0.49 0.49 0.49

Composition (Total) % 100 100 100 100 100 100 100

Properties

Spiral flow cm 11.2 14.9 17.2 19.2 19.0 25.3 24.7

Flex modulus MPa 2280 2248 2140 2144 1953 1977 2046

Flex stress MPa 73.0 75.5 69.7 71.8 69.3 66.3 70.9

Tensile stress at break MPa 56.3 59.1 53.8 47.6 46.5 46.3 46.4

Tensile strain at break % 89 99 96 85 90 113 103

Izod impact KJ/m² 53 51 49 44 44 43 49

As seen in Table 4, comparison between the comparative examples A and

working examples 11-16, compositions of the present invention comprising 0.01- 0.5 weight% of a melt flow modifier, such as pentaerythritol (Ex.11),

l,l,l-tris(hydroxymethyl)-ethane (Ex. 12), xylitol (Ex.13), sorbitol (Ex.14), dipentaerythritol (Ex.15), or tripentaerythritol (Ex.16), all brought out improvements in flowability while maintaining excellent mechanical properties.

Table 4. Examples of Different Melt Flow Modifiers

Unit Comp. Ex. 11 Ex. 12 Ex. 13 Ex. 14 Ex. 15 Ex. 16 Ex.A

Component (bv wei-ihf)

PC % 71.8 71.7 71.7 71.7 71.7 71.7 71.8

PTT % 18.0 17.9 17.9 17.9 17.9 17.9 17.9

MBS % 9.0 9.0 9.0 9.0 9.0 9.0 9.0

Pentaerythritol % 0.18

1,1,1 -tris(hydroxymethyl)

% 0.20

-ethane

Xylitol % 0.20

Sorbitol % 0.20

Dipentaerythritol % 0.10

Tripentaerythritol % 0.05

IRGAFOS^® 168 % 0.45 0.45 0.45 0.45 0.45 0.45 0.45

IRGANOX^® 1010 % 0.36 0.36 0.36 0.36 0.36 0.36 0.36

PETS % 0.45 0.45 0.45 0.45 0.45 0.45 0.45

Composition (Total) % 100 100 100 100 100 100 100

Properties

Spiral flow cm 11.5 19.3 19.2 14.1 14.0 15.1 14.0

Flex modulus MPa 2176 2021 2102 2127 2010 2002 2051

Flex stress MPa 67.2 69.3 70.8 71.0 68.1 69.3 69.2

Tensile stress at break MPa 55.1 51.7 44.9 54.4 51.8 54.7 52.9

Tensile strain at break % 103 105 87 97 95 111 104

Izod impact KJ/m² 56 48 47 59 56 53 55 While the invention has been illustrated and described in typical

embodiments, it is not intended to be limited to the details shown, since various

modifications and substitutions are possible without departing from the spirit of

the present invention. As such, modifications and equivalents of the invention

herein disclosed may occur to persons skilled in the art using no more than routine experimentation, and all such modifications and equivalents are believed to be

within the spirit and scope of the invention as defined by the following claim.

Claims

CLAIMS What is claimed is:

1. A thermoplastic composition comprising:

(a) 60-85wt% of an aromatic polycarbonate,

(b) 5-30wt% of a polytrimethylene terephthalate,

(c) 3-15wt% of an impact modifier, and

(d) 0.01-0.5wt% of a melt flow modifier;

wherein said percents are based on the total weight of the composition.

2. The thermoplastic composition of Claim 1 wherein the aromatic polycarbonate is based on bisphenol A.

3. The thermoplastic composition of Claim 1 wherein the aromatic polycarbonate has a melt mass flow rate of 5-20 g per 10 min.

4. The thermoplastic composition of Claim 1 wherein the

polytrimethylene terephthalate has an intrinsic viscosity of 0.8-1.2.

5. The thermoplastic composition of Claim 1 wherein the impact modifier is selected from the group consisting of an olefin copolymer, a core-shell graft copolymer and a mixture thereof.

6. The thermoplastic composition of Claim 5 wherein the core-shell type copolymer comprises a shell of polymethyl methacrylate.

7. The thermoplastic composition of Claim 6 wherein the core-shell type copolymer comprises a rubber core having a glass transition temperature from -

80°C to -20°C.

8. The thermoplastic composition of Claim 6 wherein the core-shell type copolymer comprises a rubber core comprising butadiene rubber or silicone rubber.

9. The thermoplastic composition of Claim 1 wherein the melt flow modifier is selected from 2,2-dimethyl-l,3-propanediol, glycerol,

1,1,1 -tris(hydroxymethyl)ethane, 1,1,1 -tris(hydroxymethyl)propane,

pentaerythritol, xylitol, sorbitol, dipentaerythritol and tripentaerythritol.

10. The thermoplastic composition of Claim 8 wherein the melt flow modifier is selected from l,l,l-tris(hydroxymethyl)ethane, pentaerythritol, dipentaerythritol and tripentaerythritol.

11. The thermoplastic composition of Claim 1 further comprising at least one additive selected from a group consisting of antioxidants, thermal stabilizers, ultraviolet light stabilizers, colorants including dyes and pigments, lubricants, hydrolysis resistants, demolding agents, and flame retardants.

12. The thermoplastic composition of Claim 1 being substantially free of a reinforcing filler.

13. A molded article comprising the thermoplastic composition of Claim

1.