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Title:
THERMOPLASTIC RESIN COMPOSITION WITH IMPROVED COMPATIBILITY
Document Type and Number:
WIPO Patent Application WO/2009/113762
Kind Code:
A3
Abstract:
Disclosed herein is a thermoplastic resin composition with improved compatibility by introducing a branched acrylic copolymer to a polycarbonate resin. The thermoplastic resin composition has good scratch resistance in addition to good colorability and appearance without a compatibilizer by improving compatibility.

Inventors:
KWON KEE HAE (KR)
KIM IL JIN (KR)
MOON HYUNG RANG (KR)
Application Number:
PCT/KR2008/007825
Publication Date:
November 05, 2009
Filing Date:
December 31, 2008
Export Citation:
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Assignee:
CHEIL IND INC (KR)
KWON KEE HAE (KR)
KIM IL JIN (KR)
MOON HYUNG RANG (KR)
International Classes:
C08L69/00
Foreign References:
JP2006257284A2006-09-28
KR20000048033A2000-07-25
JP2006342246A2006-12-21
Other References:
See also references of EP 2252657A4
Attorney, Agent or Firm:
CHOI, Duk Kyu et al. (648-23Yeoksam-dong, Gangnam-gu, Seoul 135-748, KR)
Download PDF:
Claims:

[CLAIMS] [Claim 1]

A thermoplastic resin composition comprising:

(A) about 20 or more but less than about 100 % by weight of a polycarbonate resin; and

(B) more than about 0 but not more than about 80 % by weight of a branched (meth)acrylic copolymer resin.

[Claim 2]

The thermoplastic resin composition of Claim 1, wherein said branched (meth)acrylic copolymer resin (B) has a weight average molecular weight of about 100,000 to about 3,500,000.

[Claim 3]

The thermoplastic resin composition of Claim 1, wherein said branched (meth)acrylic copolymer resin (B) has a refractive index of about 1.495 to about 1.575.

[Claim 4]

The thermoplastic resin composition of Claim 1, wherein said branched (meth)acrylic copolymer resin (B) is a copolymer of (bl) an aromatic or aliphatic methacrylate represented by the following Chemical Formula 1 or Chemical Formula 2, (b2) a mono-functional unsaturated monomer, and (b3) a branch-indueing monomer, or a mixture of copolymers thereof: [Chemical Formula 1]

wherein m is an integer from 0 to 10, and X is selected from the group consisting of a cyclohexyl group, a phenyl group, a methylphenyl group, a methylethylphenyl group, a propylphenyl group, a methoxyphenyl group, a

eyelohexylphenyl group, a chlorophenyl group, a broraophenyl group, a phenylphenyl group, and a benzylphenyl group; [Chemical Formula 2]

wherein m is an integer from 0 to 10, Y is oxygen(O) or sulfur(S), and Ar is selected from the group consisting of a cyclohexyl group, a phenyl group, a methylphenyl group, a methylethylphenyl group, a methoxyphenyl group, a eyelohexylphenyl group, a chlorophenyl group, a bromophenyl group, a phenylphenyl group, and a benzylphenyl group.

[Claim 5]

The thermoplastic resin composition of Claim 4, wherein said branched (meth)acrylic copolymer resin (B) is a copolymer of about 5 to about 99.999 % by weight of the aromatic or aliphatic methacrylate (bl), about 0 to about 85 % by weight of the mono-functional unsaturated monomer (b2), and about 0.001 to about 10 % by weight of the branch-indueing monomer, or a mixture of copolymers thereof.

[Claim 6]

The thermoplastic resin composition of Claim 4, wherein said aromatic or aliphatic methacrylate (bl) is selected from the group consisting of cyclohexyl methacrylate, phenoxy methacrylate, phenoxyethyl methacrylate, 2-ethylthiophenyl methacrylate, phenyl methacrylate, benzyl methacrylate, 2-phenylethyl methacrylate, 3-phenylpropyl methacrylate, 4-phenylbutyl methacrylate, 2-2-methy1phenylethyl methacrylate, 2-3-methylphenylethyl methacrylate, 2-4-methylphenylethyl methacrylate, 2-(4-propylphenyl)ethyl methacrylate, 2-(4-(l-methylethyl )phenyl )ethyl methacrylate, 2-(4-methoxyphenyl)ethylmethacrylate, 2-(4-cyclohexylphenyl)ethyl methacrylate, 2-(2-chlorophenyl)ethyl methacrylate, 2-(3-chlorophenyl)ethyl

methacrylate, 2-(4-chlorophenyl)ethyl methacrylate, 2-(4-bromophenyl)ethyl methacrylate, 2-(3-phenylphenyl)ethyl methacrylate, 2-(4-benzylphenyl)ethyl methacrylate, and mixtures thereof.

[Claim 7]

The thermoplastic resin composition of Claim 4, wherein said mono-functional unsaturated monomer (b2) is selected from the group consisting of methacrylic acid ester monomers including methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate; acrylic acid ester monomers including methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, hexyl acrylate, 2-ethyl hexyl acrylate; unsaturated carboxylic acid monomers including acrylic acid and methacrylic acid; acid anhydride monomers including maleic anhydride; hydroxyl group containing ester monomers including 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, and monoglycerol acrylate; and mixtures thereof.

[Claim 8]

The thermoplastic resin composition of Claim 4, wherein said branch-indueing monomer (b3) is at least one selected from the group consisting of si lane or siloxane compounds including unsaturated hydrocarbon group-containing si Iicone-containing crossl inking monomers! aromatic crosslinking monomers including divinylbenzene; vinyl group-containing monomers including 1,4-divinyloxybutane and divinylsulfone; allyl compounds including dial IyI phthalate, diallylacrylamide, trial IyI (iso)cyanurate, and trial IyI trimelitate; (poly)alkylene glycol di(meth)acrylate compounds including 1,6-hexanediol di(meth)acrylate, (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, (poly)tetramethylene glycol di(meth)acrylate, pentaerythritol tetra(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, dipentaerythritol

d

hexa(meth)acrylate, dipentaerythritol penta(meth)acrylate, and glycerol tri(meth)acrylate! and mixtures thereof.

[Claim 9]

The thermoplastic resin composition of Claim 1, wherein said thermoplastic resin composition further comprises (C) more than about O but less than about 80 % by weight of (meth)acrylic resin.

[Claim 10]

The thermoplastic resin composition of Claim 9, wherein said (meth)acrylic resin (C) has a linear structure.

[Claim 11]

The thermoplastic resin composition of Claim 10, wherein said (meth)acrylic resin (C) is a polymer of (meth)acrylic monomer, a copolymer of (meth)acrylic monomers, or mixtures thereof.

[Claim 12]

The thermoplastic resin composition of Claim 11, wherein the (meth)acrylic monomer (C) is selected from the group consisting of methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, phenyl methacrylate, benzyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, phenoxy methacrylate, phenoxy ethyl methacrylate, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, 2-ethylhexylmethacrylate, and mixtures thereof.

[Claim 13]

The thermoplastic resin composition of any one of Claims 1 to 12, wherein said resin composition further comprising additives selected from the group consisting of flame retardants, antimicrobials, releasing agents, thermal stabilizers, antioxidants, light stabilizers, compatibilizer , dyes,

inorganic fillers, surfactants, nucleating agents, coupling agents, fillers, plasticizers, impact modifiers, coloring agents, stabilizers, lubricants, antistatic agents, pigments, flameproof agents, and mixtures thereof.

[Claim 14]

The thermoplastic resin composition of Claim 13, wherein said thermoplastic resin composition has a complex viscosity (rι*) of about 1,000 Pas to about 10,000 Pas at 240 °C and 0.1 rad/s, and the ratio of n*(0.1 rad/s) / n*(100 rad/s) ranges from about 3.0 to about 100.0 at 240 °C.

Description:

[DESCRIPTION] [Invention Title]

THERMOPLASTIC RESIN COMPOSITION WITH IMPROVED COMPATIBILITY

[Technical Field]

The present invention relates to a thermoplastic resin composition with improved compatibility. More particularly, the present invention relates to a thermoplastic resin composition with improved compatibility by introducing a branched acrylic copolymer resin to a polycarbonate resin.

[Background Art]

Generally, thermoplastic resins have lower specific gravity than glasses and metals, and have good physical properties such as moldability and impact resistance. However, a drawback is poor surface scratch resistance.

In particular, polycarbonate resins have excellent mechanical strength, flame retardancy, transparency, and weatherability, in addition to good impact resistance, thermal stability, self-extinguishing property, and dimensional stability so that they have been widely used in electrical and electronic products and parts of automobiles. Further, although polycarbonate resins as engineering plastics can be a substitute for conventional glasses which need transparency and impact resistance at the same time, there is also a drawback of poor scratch resistance.

On the other hand, although a polymethylmethacrylate resin has good transparency, weatherability, mechanical strength, surface gloss, adhesive strength, and excellent scratch resistance, it has a disadvantage in that it is hard to obtain impact resistance and flame retardancy.

In order to improve the scratch resistance of plastic products, a hard coating method, which includes the steps of coating a surface of an injection-molded resin with an organic-inorganic hybrid material and curing the organic-inorganic hybrid material on the surface of the resin using heat or ultra violet light, has been conventionally used. However, because the

hard coating method requires an additional coating step, the processing time and the manufacturing cost increase and it may cause environmental problems. With recent increased interest in environmental protection and reduction of manufacturing costs, there is a need for a non-coated resin which has scratch resistance without using the hard coating method. Also, it is important to develop a resin with good scratch resistance for a housing manufacturing industry.

One attempt to improve scratch resistance of the thermoplastic resin is to alloy acrylic resin such as polymethylmethacrylate with good scratch resistance with polycarbonate resin. However, the method has a drawback in that it is difficult to obtain high transparency and colorability due to the difference between the refractive indices of the polycarbonate resin and the acrylic resin.

Korean Patent Publication Laid-open No. 2004-0079118 discloses a method of lowering the molecular weight of polycarbonate during a kneading process using metal stearic acid ester in order to improve the compatibility between a polycarbonate resin and a methacrylate resin. However, the method has a disadvantage in that a blend of the polycarbonate and the methacrylate resin has significantly low mechanical properties.

Although U.S. Patent No. 4,287,315 discloses a methacrylate resin with good impact strength using an ethylene-vinylacetate rubber, the blend of the polycarbonate and the methacrylate resin has low transparency.

Accordingly, the present inventors have developed a thermoplastic resin composition with improved scratch resistance as well as high transparency and high colorability using a branched (meth)acrylic copolymer resin with a high refractive index while blending the polycarbonate resin and the (meth)acrylic resin in order to improve the compatibility of those two resins and to reduce the difference between the refractive indices of the polycarbonate resin and the (meth)acrylic resin.

[Disclosure]

[Technical Problem]

An object of the present invention is to provide a thermoplastic resin composition with improved compatibility by introducing a branched acrylic copolymer resin to a polycarbonate resin.

Another aspect of the present invention provides a thermoplastic resin composition with good scratch resistance, while minimizing deterioration of transparency and colorability.

Another aspect of the present invention provides a thermoplastic resin composition applicable for various parts of electrical and electronic appliances, parts of automobiles, lenses, window glasses, and the like, due to its good scratch resistance, high colorability, and high transparency.

Another aspect of the present invention provides a molded article produced from the thermoplastic resin composition.

Other aspects, features and advantages of the present invention will be apparent from the ensuing disclosure and appended claims.

[Technical Solution]

The thermoplastic resin composition of the present invention comprises

(A) about 20 or more but less than about 100 % by weight of a polycarbonate resin; and (B) more than about 0 but not more than about 80 % by weight of a branched (meth)acrylic copolymer resin.

In an exemplary embodiment, the thermoplastic resin composition may comprise (A) about 40 to about 90 % by weight of a polycarbonate resin; and

(B) about 10 to about 60 % by weight of a branched (meth)acrylic copolymer resin.

In an exemplary embodiment, the branched (meth)acrylic copolymer resin (B) may have a weight average molecular weight of about 100,000 to about 3,500,000. In another exemplary embodiment, the methacrylic copolymer resin (B) may have a weight average molecular weight of about 500,000 to about 3,000,000. In another exemplary embodiment, the methacrylic copolymer resin (B) may have a weight average molecular weight of about 1,000,000 to about

2,500,000.

Further, the branched (meth)acrylic copolymer resin (B) may have a refractive index of about 1.495 to about 1.575. In an exemplary embodiment, the refractive index may be about 1.50 to about 1.575, or about 1.51 to about 1.575.

The branched (meth)acrylic copolymer resin (B) may be a copolymer of (bl) an aromatic or aliphatic methacrylate, and (b3) a branch-indueing monomer, or a mixture of copolymers thereof. In an exemplary embodiment, the branched (meth)acrylic copolymer resin (B) may further comprise a mono-functional unsaturated monomer.

In an exemplary embodiment, the branched (meth)acrylic copolymer resin (B) may be a copolymer of about 5 to about 99.999 % by weight of the aromatic or aliphatic methacrylate (bl), about 0 to about 85 % by weight of the mono-functional unsaturated monomer (b2), and about 0.001 to about 10 % by weight of the branch-indueing monomer, or a mixture of copolymers thereof.

In another exemplary embodiment, the thermoplastic resin composition may further comprise (C) more than about 0 but less than about 80 % by weight of a (meth)acrylic resin. In an embodiment, the thermoplastic resin composition may further comprise about 10 to about 30 % by weight of a (meth)acrylic resin, In another embodiment, the thermoplastic resin composition may further comprise about 30 to about 60 % by weight of a (meth)acrylic resin. The (meth)acrylic resin (C) may have a linear structure.

In an exemplary embodiment, the (meth)acrylic resin (C) is a polymer, a copolymer of one type or more (meth)acrylic monomers, or a mixture thereof.

The thermoplastic resin composition of the present invention further comprises additives selected from the group consisting of flame retardants, antimicrobials, releasing agents, thermal stabilizers, antioxidants, light stabilizers, compatibi lizer , dyes, inorganic fillers, surfactants, nucleating agents, coupling agents, fillers, plasticizers, impact modifiers, coloring agents, stabilizers, lubricants, antistatic agents, pigments, flameproof agents, and a mixture thereof.

In an exemplary embodiment, the thermoplastic resin composition may have a complex viscosity (η,*) of about 1,000 Pas to about 10,000 Pas at 240 °C and 0.1 rad/s. In another exemplary embodiment, the thermoplastic resin composition may have a complex viscosity (η,*) of about 1,000 Pas to about 5,000 Pas at 240 ° C and 0.1 rad/s. In another embodiment, the complex viscosity may be about 5,500 Pas to about 10,000 Pas. Furthermore, at 240 °C , the ratio of η,*(0.1 rad/s) / rι*(100 rad/s) ranges from about 3.0 to about 100.0. In an exemplary embodiment, the ratio of η,*(0.1 rad/s) / η,*(100 rad/s) ranges from about 3.5 to about 30.0. In another exemplary embodiment, the ratio of η,*(0.1 rad/s) / η,*(100 rad/s) ranges from about 30.0 to about 75.0. In other exemplary embodiment, the ratio of rι*(0.1 rad/s) / η,*(100 rad/s) ranges from about 75.0 to about 100.0.

The present invention provides a molded article produced from the foregoing thermoplastic resin composition. The present invention now will be described more fully hereinafter in. the following detailed description of the invention.

[Description of Drawings]

FIG. Ka) is a scratch profile of a specimen prepared in Example 2 and (b) is a scratch profile of a specimen prepared in Comparative Example 3.

FIG. 2(a) is a transmission electron microscope (TEM) image of a specimen prepared in Example 2 and (b) is a transmission electron microscope (TEM) image of a specimen prepared in Comparative Example 2.

FIG. 3 is a graph comparing viscosity behavior of a specimen prepared in Example 2 with viscosity behavior of a specimen prepared in Comparative Example 2.

[Best Mode] (A) Polycarbonate Resin

The polycarbonate resin of the present invention may be prepared by any

conventional method well known to those skilled in the art, that is, the polycarbonate resin may be prepared by reacting dihydric phenol compound with phosgene in the presence of a catalyst and a molecular weight controlling agent. Also, the polycarbonate resin may be prepared by transesterification of a carbonate precursor such as dihydric phenol compound and diphenylcarbonate.

The dihydric phenol compound may be a bisphenol compound, preferably 2,2-bis(4-hydroxyphenyl)propane (bisphenol A). The bisphenol A may be partially or totally substituted with another dihydric phenol. In addition to bisphenol A, examples of dihydric phenols may include hydroquinone, 4,4' -dihydroxydiphenyl , bis(4-hydroxyphenyl )methane, 1 , 1-bis(4-hydroxypheny1 )eye1ohexane,

2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane, bis(4-hydroxyphenyl)sulfide, bis(4-hydroxypheny1 )sul fone, bis(4-hydroxypheny1 )sul foxide, bis(4-hydroxypheny1)ketone, bis(4-hydroxyphenyl)ether, etc., and also include halogenated bisphenol such as 2,2-bis(3,5-dibromo-4-hyroxyphenyl)propane.

However, the dihydric phenol compound applicable for preparing the polycarbonate resin is not limited to the aforementioned compounds.

Furthermore, the polycarbonate resin used in the present invention may be a homopolymer or a copolymer of two or more types of dihydric phenols, or a mixture thereof.

Examples of polycarbonate resin in the present invention may also include, without limitation, linear polycarbonate resin, branched polycarbonate resin, polyester carbonate copolymer resin and the like.

The linear polycarbonate resin may be, without limitation, a bisphenol A-based polycarbonate resin. The branched polycarbonate resin may be prepared by reacting poly-functional aromatic compounds such as trimelitic anhydride, trimelitic acid and etc., with dihydric phenol compounds and carbonate precursors. The polyester carbonate copolymer resin may also be prepared, without limitation, by reacting di-functional carboxylic acid with dihydric phenol compounds and carbonate precursors. The linear polycarbonate resin,

the branched polycarbonate resin and the polyester carbonate copolymer resin can be used alone or in combination with one another.

According to the present invention, the polycarbonate resin may be used in an amount of about 20 or more but less than about 100 parts by weight, preferably about 40 to about 90 parts by weight. If the. amount is less than about 20 parts by weight, it is difficult to obtain good mechanical properties in the polycarbonate resin. In order to obtain scratch resistance, it is preferable that the amount is about 45 to about 80 % by weight.

(B) Branched (meth)acrylic copolymer resin

The branched (meth)acrylic copolymer resin of the present invention may be a copolymer of (bl) an aromatic or aliphatic methacrylate and (b3) a branch-indueing monomer, or mixtures of copolymers thereof. The branched (meth)acrylic copolymer resin may have a branched structure with partial crosslinking. In an exemplary embodiment, the branched (meth)acrylic copolymer resin may further comprise (b2) a mono-functional unsaturated monomer .

In an exemplary embodiment, the branched (meth)acrylic copolymer resin of the present invention may be prepared by polymerizing a monomer mixture comprising (bl) about 5 to about 99.999 % by weight of an aromatic or aliphatic methacrylate, (b2) about 0 to about 85 % by weight of a mono-functional unsaturated monomer, and (b3) about 0.001 to about 10 % by weight of a branch-indueing monomer.

The aromatic or aliphatic methacrylate (bl) may have a hydrocarbon group having 6 to 20 carbon atoms, and may be represented by the following Chemical Formula 1 or Chemical Formula 2.

O

[Chemical Formula 1]

(wherein m is an integer from 0 to 10, and X is selected from the group consisting of a cyclohexyl group, a phenyl group, a methylphenyl group, a methylethylphenyl group, a propylphenyl group, a methoxyphenyl group, a cyclohexylphenyl group, a chlorophenyl group, a bromophenyl group, a phenylphenyl group, and a benzylphenyl group.)

[Chemical Formula 2]

(wherein m is an integer from 0 to 10, Y is oxygen (0) or sulfur (S), and Ar is selected from the group consisting of a cyclohexyl group, a phenyl group, a methylphenyl group, a methylethylphenyl group, a methoxyphenyl group, a cyclohexylphenyl group, a chlorophenyl group, a bromophenyl group, a phenylphenyl group, and a benzylphenyl group.)

Examples of the aromatic or aliphatic methacrylate (bl) may include, but are not limited to, cyclohexyl methacrylate, phenoxy methacrylate, phenoxyethyl methacrylate, 2-ethylthiophenyl methacrylate, phenyl methacrylate, benzyl methacrylate, 2-phenylethyl methacrylate, 3-phenylpropyl methacrylate, 4-phenylbutyl methacrylate, 2-2-methylphenylethyl methacrylate, 2-3-methylphenylethyl methacrylate, 2-4-methylphenylethyl methacrylate, 2-(4-propylphenyl)ethyl methacrylate, 2-(4-(l-methylethyl )phenyl)ethyl methacrylate, 2-(4-methoxyphenyl)ethylmethacrylate, 2-(4-cyclohexylphenyl)ethyl methacrylate, 2-(2-chlorophenyl)ethyl methacrylate, 2-(3-chlorophenyl)ethyl methacrylate, 2-(4-chlorophenyl)ethyl methacrylate, 2-(4-bromophenyl)ethyl methacrylate, 2-(3-phenylphenyl)ethyl methacrylate, and 2-(4-benzylphenyl)ethyl methacrylate, and the like. They

may be used alone or in combination with one another.

The aromatic or aliphatic methacrylate (bl) may be used in an amount of about 5 to about 99.999 % by weight, preferably about 20 to about 99 % by weight, more preferably about 45 to about 90 % by weight, based on the total weight of the monomer mixture. If the amount of the aromatic or aliphatic methacrylate (bl) is less than about 5 % by weight, the average refractive index of polymerized (meth)acrylic copolymer may be lowered to less than 1.495.

The mono-functional unsaturated monomer (b2) may include, but is not limited to, methacrylic acid ester monomers including methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate; acrylic acid ester monomers including methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, hexyl acrylate, 2-ethyl hexyl acrylate; unsaturated carboxylic acid monomers including acrylic acid and methacrylic acid; acid anhydride monomers including maleic anhydride; hydroxyl group containing ester monomers including 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, and monoglycerol acrylate; and a mixture thereof.

The branched (meth)acrylic copolymer resin may optionally comprise the mono-functional unsaturated monomer (b2). The mono-functional unsaturated monomer (b2) may be used in an amount of about 85 % by weight or less, preferably about 1 to about 70 % by weight, more preferably about 10 to about 60 % by weight based on the total monomer mixture.

Examples of the branch-indueing monomer (b3) may include, but are not limited to, si Iicone-containing branch-indueing monomer having a vinyl functional group, ester-containing branch-indueing monomer, aromatic branch-indueing monomer, and the like. These monomers may be used alone or in combination with one another. The number of the functional groups of the branch-indueing monomer may be from 1 to 4. A branched copolymer having ultra-high molecular weight with partial crosslinking may be prepared by using the branch-indueing monomers having such functional groups.

Examples of the branch-indueing monomer (b3) may include si lane or siloxane compounds, aromatic crossl inking monomers, vinyl group-containing monomers, allyl compounds, polyalkylene glycol di(meth)acrylate compounds, and the like.

Specific examples of the branch-indueing monomer (b3) may include si lane or siloxane compounds including unsaturated hydrocarbon group-containing si Iicone-containing crossl inking monomers such as divinyl tetramethyl disiloxane, and tetramethyl tetravinyl cyclotetrasiloxane; aromatic crossl inking monomers including divinylbenzene! vinyl group-containing monomers including 1,4-divinyloxybutane and divinylsulfone! allyl compounds including dial IyI phthalate, diallylacrylamide, trial IyI (iso)cyanurate, and trial IyI trimelitate; and (poly)alkylene glycol di(meth)acrylate compounds including 1,6-hexanediol di(meth)acrylate, (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, (poly)tetramethylene glycol di(meth)acrylate, pentaerythritol tetra(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, dipentaerythritol penta(meth)acrylate, glycerol tri(meth)acrylate, and the like. They may be used alone or in combination with one another.

The branch-indueing monomer (b3) may be used in an amount of about 0.001 to about 10 % by weight, preferably about 0.01 to about 7 % by weight, more preferably about 0.1 to about 5 % by weight. If the amount is less than about 0.001 % by weight, an ultra-high molecular weight branched structure cannot be obtained, and if the amount is more than about 10 % by weight, processability and compatibility with a polycarbonate resin may decrease.

The branched (meth)acrylic copolymer resin (B) may be prepared by conventional methods such as bulk polymerization, emulsion polymerization, and suspension polymerization.

The branched (meth)acrylic copolymer resin (B) may have a higher refractive index than conventional acrylic copolymers. Conventional

polycarbonates have a refractive index of about 1.590 and polymethylmethacrylates have a refractive index of about 1.490. The branched (meth)acrylic copolymer resin of the present invention has a refractive index in between, that is, from about 1.495 to about 1.575. In some embodiments, the branched (meth)acrylic copolymer resin may have a refractive .index of about 1.50 to about 1.575, or about 1.51 to about 1.575.

Furthermore, the branched (meth)acrylic copolymer may have a weight average molecular weight of about 100,000 to about 3,500,000. In an exemplary embodiment, the branched (meth)acrylic copolymer may have a weight average molecular weight of about 500,000 to about 3,000,000. In another exemplary embodiment, the branched (meth)acrylic copolymer may have a weight average molecular weight of about 1,000,000 to about 2,500,000.

The branched (meth)acrylic copolymer resin (B) may be used in an amount of more than about 0 but not more than about 80 % by weight, preferably about 5 to about 70 % by weight, more preferably about 10 to about 50 % by weight, most preferably about 10 to about 40 % by weight. When the branched (meth)acrylic copolymer resin (B) is used in an the amount of more than about 80 % by weight, mechanical properties and moldability may be deteriorated.

(C) (Meth)acrylic resin

The thermoplastic resin composition optionally further comprises a (meth)acrylic resin (C). The (meth)acrylic resin may be a polymer or a copolymer of one or more of (meth)acrylic monomers, or mixtures thereof. In addition, the (meth)acrylic resin may have a linear structure.

Examples of the (meth)acrylic monomer may include, but are not limited to, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, phenyl methacrylate, benzyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, phenoxy methacrylate, phenoxy ethyl methacrylate, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, 2-ethylhexylmethacrylate, and the like. These

(meth)acrylic monomers may be used alone or in combination with one another.

The (meth)acrylic resin (C) may be prepared by conventional methods such as bulk polymerization, emulsion polymerization, and suspension polymerization, and may be easily carried out by those skilled in the art.

Further, the (meth)acrylic resin (C) may be a homopolymer or a copolymer of (meth)acrylic monomers, or mixtures thereof.

The (meth)acrylic resin (C) may be used in an amount of less than about 80 % by weight, preferably about 5 to about 70 % by weight, more preferably about 10 to about 50 % by weight, most preferably about 10 to about 40 % by weight. When the (meth)acrylic resin (C) is used in an the amount of more than about 80 % by weight, good mechanical properties cannot be obtained.

Generally, when a polycarbonate resin is blended with a (meth)acrylic resin, the problems of low colorability and appearance occur in the ratio of about 20—80 : about 80—20 parts by weight due to their low compatibility, thus it is important to improve compatibility in the ratio range.

As such, copolymer particles having a branched structure (B) prevent phase separation between the polycarbonate resin (A) and the (meth)acrylate resin (C). Further, in the melting state, the phase separation may be minimized due to a decrease in viscosity so that compatibility between these heterogeneous resins may be improved.

In addition, when a mixture of the methacrylic copolymer with high refractive index (B) and the (meth)acrylic resin (C) is blended with the polycarbonate resin, the difference between the refractive index of the (meth)acrylic resin (C) and the refractive index of the polycarbonate may be lowered due to the increased refractive index of the methacrylic copolymer resin (B). Therefore, it is possible to improve compatibility and transparency by preventing the deterioration of transparency and colorability usually occurring in a conventional mixture of a (meth)acrylic resin and a polycarbonate resin due to the difference between the refractive index of the two resins. In addition, it is possible to prepare a resin composition having high transparency and colorability by improving scratch resistance in a

conventional polycarbonate resin.

The thermoplastic resin composition may have improved compatibility by lowering complex viscosity. In an exemplary embodiment, the thermoplastic resin composition may have a complex viscosity (η,*) of about 1,000 Pas to about 10,000 Pas at 240 0 C and 0.1 rad/s. In another exemplary embodiment, the thermoplastic resin composition may have a complex viscosity (η,*) of about 1,000 Pas to about 5,000 Pas at 240 °C and 0.1 rad/s. In another embodiment, the complex viscosity may be about 5,500 Pas to about 10,000 Pas. Furthermore, at 240 °C , the ratio of η,*(0.1 rad/s) / rt*(100 rad/s) ranges from about 3.0 to about 100.0. When the complex viscosity is outside of the above ranges, compatibility may be deteriorated due to phase separation. In an exemplary embodiment, the ratio of η,*(0.1 rad/s) / η,*(100 rad/s) ranges from about 3.5 to about 30.0. In another exemplary embodiment, the ratio of η,*(0.1 rad/s) / iχ*(100 rad/s) ranges from about 30.0 to about 75.0. In another exemplary embodiment, the ratio of η,*(0.1 rad/s) / rι*(100 rad/s) ranges from about 75.0 to about 100.0.

The thermoplastic resin composition may further comprise additives selected according to the needs. The additives may include flame retardants, antimicrobials, releasing agents, thermal stabilizers, antioxidants, light stabilizers, compatibilizer, pigments, inorganic fillers, surfactants, nucleating agents, coupling agents, fillers, plasticizers, impact modifiers, coloring agents, stabilizers, lubricants, antistatic agents, dyes, flameproof agents, and the like. These additives may be used alone or in combination with one another.

The present invention provides a molded article produced from the foregoing thermoplastic resin composition. The molded article has a total light transmittance of about 8 to about 50 % measured by means of a Haze meter NDH 2000 manufactured by Nippon Denshoku Co. Ltd., a meltflow index of about 5 to about 15 g/10 min measured in accordance with ASTM D 1238, and a scratch width of about 210 to about 295 m measured by ball-type scratch profile test (BSP test).

The thermoplastic resin composition of the present invention may be prepared by conventional methods. For example, the aforementioned components and other additives may be mixed in a mixer together and the mixture may be melt-extruded through a conventional extruder in a pellet form, and then the resin pellets may be used to prepare plastic molded articles by injection and extrusion.

Since the thermoplastic resin composition has excellent scratch resistance, colorabi lity, and transparency, the thermoplastic resin composition may be molded into various articles such as housings of electrical and electronic goods, parts of automobiles, lenses, window glasses, and the like.

In some exemplary embodiments, the scratch-resistant thermoplastic resin composition may be used in housings of electrical and electronic products such as TV, audio sets, washing machines, cassette players, MP3, telephones, game devices, video players, computers, photocopiers, and the like.

In an exemplary embodiment, the scratch-resistant thermoplastic resin composition may be used for internal or external parts of automobiles such as dashboard panels, instrumental panels, door panels, quarter panels, wheel covers, and the like.

The molding methods may be, but are not limited to, extrusion, injection, or casting molding, and may be easily carried out by those skilled in the art .

The invention may be better understood by reference to the following examples which are intended for the purpose of illustration and are not to be construed as in any way limiting the scope of the present invention, which is defined in the claims appended hereto.

[Mode for Invention] Example

(A) Polycarbonate resin

Bisphenol-A linear polycarbonate with a weight average molecular weight of 25,000 (Mw) manufactured by Teijin Chemicals Ltd. of Japan (product name: PANLITE L-1250 WP) was used.

(B) Branched acrylic copolymer resin

(Bl) Branched acrylic copolymer resin-1

The branched copolymer resin was prepared by conventional suspension polymerizing 57 parts by weight of methylmethacrylate monomer, 40 parts by weight of phenoxy ethyl methacrylate and 3 parts by weight of divinyltetramethyldisiloxane. The resulting copolymer has a refractive index of 1.510 and a weight average molecular weight of 2,000,000 g/mol .

(B2) Branched acrylic copolymer resin-2

The branched copolymer resin was prepared by conventional suspension polymerizing 27 parts by weight of methylmethacrylate monomer, 70 parts by weight of phenoxy ethyl methacrylate and 3 parts by weight of divinyltetramethyldisiloxane. The resulting copolymer has a refractive index of 1.530 and a weight average molecular weight of 2,000,000 g/mol.

(B3) Branched acrylic copolymer resin-3

The branched copolymer resin was prepared by conventional suspension polymerizing 47 parts by weight of methylmethacrylate monomer, 50 parts by weight of phenoxy ethyl methacrylate and 3 parts by weight of divinyltetramethyldisiloxane. The resulting copolymer has a refractive index of 1.530 and a weight average molecular weight of 2,000,000 g/mol.

(B4) Branched acrylic copolymer resin-4

The branched copolymer resin was prepared by conventional suspension polymerizing 17 parts by weight of methylmethacrylate monomer, 40 parts by weight of phenoxy ethyl methacrylate, 40 parts by weight of cyclohexyl methacrylate, and 3 parts by weight of divinyltetramethyldisiloxane. The resulting copolymer has a refractive index of 1.530 and a weight average molecular weight of 2,000,000 g/mol.

(C) (Meth)acrylic resin

Polymethylmethacrylate resin with a weight average molecular weight of 92,000 (Mw) manufactured by LG MMA Ltd. of South Korea (product name: L84) was used.

Examples 1—6 and Comparative Examples 1—3

The components as shown in Table land a MBS-based impact modifier were added to a conventional mixer, and the mixture was extruded through a conventional twin screw extruder (L/D=29, F=45 mm) to prepare a product in pellet form. The pellets were dried at 80 °C for 6 hours and then molded into test specimens in a 6 Oz injection molding machine.

The compatibility and the transparency were estimated by measuring flow mark, transparency, color and transmittance. The flow mark, transparency and color appeared on the test specimen were measured by naked eyes. The improved compatibility was confirmed by phase separation behavior through TEM images. The test specimen with dimensions of L 90 mm x W 50 mm x T 2.5 mm was used for measuring the above appearance properties.

The total light transmittance was measured by Haze meter NDH 2000 manufactured by Nippon Denshoku, and calculated by adding diffuse light transmittance (DF) and parallel transmittance (PT). It can be estimated that the higher total light transmittance is, the better transparency is.

The meltflow index of the test specimen was measured in accordance with

ASTM D 1238 at 220 "C using a balance weight of 10 kg.

The scratch resistance was measured by ball-type scratch profile (BSP) test. The BSP was conducted by applying a scratch of a length of 10—20 mm onto resin specimens with dimensions of L 90 mm x W 50 mm x T 2.5 mm at a load of 1,000 g and a scratch speed of 75 mm/min, using a metal spherical tip with a diameter of 0.7 mm and measuring a profile of the applied scratch through a surface profile analyzer (XP-I) manufactured by Ambios Corporation which provides a scratch profile through surface scanning using a metal stylus tip with a diameter of 2 μm. The scratch resistance was evaluated from a scratch width by the measured profile.

FIG. Ka) was a scratch profile picture of a test specimen prepared in Example 2 measured by BSP test, and FIG Kb) was a scratch profile picture of a test specimen prepared in Comparative Example 3. The results of scratch width were shown in the following Table 1.

On the other hand, in order to analyze phase behavior, TEM images of resin compositions of Example 2 and Comparative Example 2 were respectively shown in FIGS. 2(a) and 2(b).

The viscosity behaviors of resin compositions of Example 2 and Comparative Example 2 were measured by ARES (Advanced Rheometric Expansion System) manufactured by Rheometric Scientific Corporation at 240 "C , and were shown in FIG. 3.

[Table 1]

(*) : impossible to obtain the result of Meltflow index of Comparative Example 3 in the above conditions.

As shown in Table 1, when the polycarbonate, (meth)acrylic resin and the branched acrylic copolymer resin are blended, improved scratch resistance is exhibited, compared to using the polycarbonate only as in Comparative Example 3, which is also confirmed by the scratch profile of FIG. 1.

It is seen that Comparative Examples 1 and 2 in which the branched acrylic copolymer resin (B) was not added show flow mark and opaque milky appearance due to low compatibility between the two resins. Examples 1 to 6 using the branched acrylic copolymer (B) exhibit better transparency and flow mark and high total light transmittance, compared to Comparative Examples 1 to 2. Furthermore, Example 2 and Example 5 including two different branched copolymers which had the same refractive index, but were prepared using different amounts of acrylic monomer exhibit similar levels of transparency and flow mark. Also, Example 6 using two different acrylic monomers which have a high refractive index exhibits similar results.

The improved compatibility is caused by the control of refractive index and the minimization of phase separation, and the result of complex viscosity of the composition is confirmed through the results of ARES. As shown in FIG.3, the complex viscosity measured by ARES shows a tendency to decrease, as the frequency (rad/s) increases from 0.1 to 100, and Example 2 exhibits a more significant decrease than Comparative Example 2.

Furthermore, when two similar branched acrylic copolymers are used, Example 2 including the branched acrylic copolymer with a high refractive index exhibits better transparency and compatibility and high total light transmittance, as compared to Example 1.

The improved compatibility between polycarbonate and polymethylmethacrylate is confirmed in TEM image, and also shown in FIG. 2. Although Comparative Example 2 exhibits that the polymethylmethacrylate has a continuous phase and large domain in a polycarbonate base due to lowered compatibility, Example 2 exhibits improved compatibility since the phase size of polymethylmethacrylate decreases and spherical phase behavior is shown.

In the above, the present invention was described based on the specific preferred embodiments, but it should be apparent to those ordinarily skilled in the art that various changes and modifications can be added without departing from the spirit and scope of the present invention which will be defined in the appended claims.