JP2002528589A - Polycarbonate resin / ABS graft copolymer / SAN blend - Google Patents

Abstract

  (57) [Summary] Thermoplastic blends containing aromatic polycarbonate resins, acrylonitrile-butadiene-styrene graft copolymers, and styrene acrylonitrile with reduced styrene-acrylonitrile oligomer content have improved balance between flow properties and ductility.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD OF THE INVENTION

The present invention relates to thermoplastic resin compositions, and more specifically, to polycarbonate ("PC") resins, acrylonitrile-butadiene-styrene ("A
BS ") a thermoplastic resin composition comprising a graft copolymer and a styrene-acrylonitrile (" SAN ") copolymer.

[0002]

[Prior art]

Polycarbonate resin is a tough, hard engineering thermoplastic with good impact strength. However, processing may be difficult due to the flow characteristics of the polycarbonate resin. Various attempts have been made in the past to blend polycarbonate resins with other polymeric modifiers in order to improve their flow properties while maintaining the toughness and impact resistance of the polycarbonate resins. For example, ABS
By blending the graft copolymer with a polycarbonate resin, a low-cost blend having improved processing characteristics while maintaining good impact resistance has been obtained (Gra).
Bowski U.S. Pat. No. 3,130,177 and Plastics World
November 1977, pp. 5-58). However, various attempts to further improve the flow properties of polycarbonate resin / ABS graft copolymer blends have resulted in brittle materials and severely reduced heat deflection temperatures ("HDT"). I have. It would be highly desirable and useful to be able to produce a polycarbonate resin / ABS graft copolymer blend having good flow properties while having good low temperature ductility and high HDT.

[0003]

Summary of the Invention

In a first aspect, the present invention provides (a) an aromatic polycarbonate resin, (b) an acrylonitrile-butadiene-styrene graft copolymer, and (c) a styrene-acrylonitrile copolymer having a reduced styrene-acrylonitrile oligomer content. The present invention relates to a thermoplastic resin composition containing:

[0004] The resin composition of the present invention has an improved balance between flow characteristics and ductility.

In a second aspect, the invention involves blending an aromatic polycarbonate resin, an acrylonitrile-butadiene-styrene graft copolymer, and a styrene-acrylonitrile copolymer having a reduced styrene-acrylonitrile oligomer content. The present invention relates to a method for producing a thermoplastic resin composition.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION

In a preferred embodiment, the thermoplastic resin composition of the present invention comprises 40 to 95 pbw, preferably 50 to 100 parts by weight ("pbw") of the thermoplastic resin composition.
~ 90 pbw, more preferably 55-80 pbw aromatic polycarbonate resin and 3-58 pbw, preferably 7-47 pbw, more preferably 10-4
0 pbw ABS graft copolymer, 2-57 pbw, preferably 3-43 pbw
bw, more preferably 5-35 pbw SAN.

Aromatic polycarbonate resin The aromatic polycarbonate resin component of the composition of the present invention comprises one or more aromatic polycarbonate resins. Aromatic polycarbonate resins suitable for use as the aromatic polycarbonate resin component of the thermoplastic resin composition of the present invention are known compounds, and their production and properties are described, for example, in US Pat. No. 3,169,121.
Nos. 4,487,896 and 5,541,999, the disclosures of each of which are incorporated herein by reference.

In a preferred embodiment, the aromatic polycarbonate resin component of the present invention comprises a dihydric phenol of the following structural formula (I): HO-A-OH (I) wherein A is a divalent aromatic group ) And a carbonate precursor, and comprises a structural unit of the following formula (II):

[0009]

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Wherein A is as defined above.

The term “divalent aromatic group” as used herein refers to a divalent group containing only one aromatic ring, such as phenylene, for example, a divalent group containing a fused aromatic ring system, such as naphthalene. And divalent groups comprising two or more aromatic rings linked by non-aromatic bonds such as, for example, alkylene, alkylidene or sulfonyl groups, any one or more sites on which aromatic ring is, for example, a halogen group or It may be substituted with a (C ₁ -C ₆ ) alkyl group or the like.

In a preferred embodiment, A is a divalent aromatic group of formula (III)

[0013]

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Suitable dihydric phenols include, for example, 2,2-bis (4-hydroxyphenyl) propane (“bisphenol A”), 2,2-bis (3,5-dimethyl-4-)
Hydroxyphenyl) propane, bis (4-hydroxyphenyl) methane, 4,
4-bis (4-hydroxyphenyl) heptane, 3,5,3 ', 5'-tetrachloro-4,4'-dihydroxyphenylpropane, 2,6-dihydroxynaphthalene, hydroquinone, 2,4'-dihydroxyphenylsulfone There are one or more of these. In a highly preferred embodiment, the dihydric phenol is bisphenol A
It is.

[0015] The carbonate precursor is one or more of a carbonyl halide, a carbonate or a haloformate. Suitable carbonyl halides include, for example, carbonyl bromide and carbonyl chloride. Suitable carbonates include, for example, diphenyl carbonate, dichlorophenyl carbonate, dinaphthyl carbonate, phenyltolyl carbonate and ditolyl carbonate. Suitable haloformates include bishaloformates of dihydric phenols (such as hydroquinone) or glycols (such as ethylene glycol and neopentyl glycol). In a very preferred embodiment,
The carbonate precursor is carbonyl chloride.

[0016] Suitable aromatic polycarbonate resins include linear aromatic polycarbonate resins,
There are branched aromatic polycarbonate resins. Suitable linear aromatic polycarbonate resins include, for example, bisphenol A polycarbonate resins. Suitable branched polycarbonates are known and are made by reacting a polyfunctional aromatic compound with a dihydric phenol and a carbonate precursor to form a branched polymer. For example, US Pat. Nos. 3,544,514, 3,635,895 and 4001,
No. 184, the disclosure of each of which is incorporated herein by reference. Polyfunctional compounds are generally aromatic and contain three or more functional groups, the functional groups being carboxyl, carboxylic anhydride, phenol, haloformate or mixtures thereof, for example 1,1,1-tri- (4-hydroxyphenyl) ethane, 1,3,5-trihydroxybenzene, trimellitic anhydride, trimellitic acid, trimellityl trichloride, 4-chloroformylphthalic anhydride,
Examples include pyromellitic acid, pyromellitic dianhydride, mellitic acid, mellitic anhydride, trimesic acid, benzophenonetetracarboxylic acid, and benzophenonetetracarboxylic dianhydride. Preferred polyfunctional aromatic compounds are 1,1,1-tri (4-hydroxyphenyl) ethane, trimellitic anhydride or trimellitic acid, or a haloformate derivative thereof.

In a preferred embodiment, the polycarbonate resin component of the present invention is a linear polycarbonate resin derived from bisphenol A and phosgene.

In a preferred embodiment, the weight average molecular weight of the polycarbonate resin is about 10% as determined by gel permeation chromatography using polystyrene as a standard.
000 to about 200,000 g / mol, and in another preferred embodiment, the polycarbonate resin has a weight average molecular weight of about 10,000 to about 100,000 g / mol. Such resins are typically prepared in methylene chloride at 25 ° C. from about 0.3 to about 1.5 dl / g.
It has an intrinsic viscosity of.

The polycarbonate resin is produced by a known method such as interfacial polymerization, transesterification, solution polymerization or melt polymerization.

[0020] Copolyester-carbonate resins are also suitable for use as the aromatic polycarbonate resin component of the present invention. Copolyester-carbonate resins suitable for use as the aromatic polycarbonate resin component of the thermoplastic resin composition of the present invention are known compounds whose manufacture and properties are described, for example, in U.S. Pat. No. 3,169,91.
21, No. 4,430,484 and No. 4,487,896, the disclosures of each of which are incorporated herein by reference.

The copolyester-carbonate resin contains carbonate groups, carboxylate groups and aromatic carbocyclic groups as repeat units in the polymer chain, at least some of the carbonate groups being aromatic carbocyclic groups. Linear or random branched polymers directly attached to a ring carbon atom are included.

In a preferred embodiment, the copolyester-carbonate resin component of the present invention is derived from a carbonate precursor, one or more dihydric phenols and one or more dicarboxylic acids or dicarboxylic acid equivalents. In a preferred embodiment, the dicarboxylic acid is of the following formula (IV)

[0023]

Embedded image

Wherein A ′ is alkylene, alkylidene, cycloaliphatic or aromatic, preferably wherein one or more sites on the unsubstituted phenylene group or on the aromatic ring are each independently a (C ₁ -C ₆ ) alkyl Is a substituted phenylene group. The copolyester-carbonate resin comprises a first structural unit of the above formula (II) and a second structural unit of the following formula (V).

[0025]

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Wherein A ′ is as defined above.

[0027] Suitable carbonate precursors and dihydric phenols are those set forth above.

Suitable dicarboxylic acids include, for example, phthalic acid, isophthalic acid, terephthalic acid,
Dimethyl terephthalic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dimethylmalonic acid,
1,12-dodecanoic acid, cis-1,4-cyclohexanedicarboxylic acid, tra
There are ns-1,4-cyclohexanedicarboxylic acid, 4,4'-bisbenzoic acid, and naphthalene-2,6-dicarboxylic acid. Suitable dicarboxylic acid equivalents include, for example, the anhydride, ester or halide derivatives of the above dicarboxylic acids, such as phthalic anhydride, dimethyl terephthalate, succinyl chloride, and the like.

In a preferred embodiment, the dicarboxylic acid is an aromatic dicarboxylic acid, more preferably one or more of terephthalic acid and isophthalic acid.

In a preferred embodiment, the ratio of ester bonds to carbonate bonds present in the copolyester-carbonate resin is from 0.25 to 0.9 ester bonds per carbonate bond.

In a preferred embodiment, the copolyester-carbonate copolymer is about 1000
It has a weight average molecular weight of 0 to about 200,000 g / mol.

The copolyester-carbonate resin is manufactured by a known method such as, for example, interfacial polymerization, transesterification, solution polymerization or melt polymerization.

ABS Graft Copolymer The ABS graft copolymer component of the composition of the present invention comprises one or more ABS graft copolymers. ABS graft copolymers suitable for use as the ABS graft copolymer component of the compositions of the present invention are well known in the art. The ABS graft copolymer is a two-phase system based on a continuous phase of a styrene-acrylonitrile (SAN) copolymer and a dispersed elastomer phase (typically of a butadiene rubber type). A small amount of styrene and acrylonitrile are grafted on the rubber particles to compatibilize the two phases.

The three main methods that can be used for the synthesis of ABS include emulsion polymerization, bulk polymerization and suspension polymerization or a combination thereof. Emulsion polymerization of ABS is a two-step method in which butadiene is polymerized to synthesize a rubber latex and then acrylonitrile and styrene are added. In the second-stage polymerization, a SAN continuous phase is formed and the rubber is polymerized. Grafting occurs. The rubber content of the ABS graft synthesized by emulsion polymerization is about 10-9.
0% by weight, and the SAN may comprise about 10-9% of the ABS graft composition.
Graft 0% by weight. The ratio of styrene to acrylonitrile is 50:50 to 85:
Fifteen. When synthesized by emulsion polymerization, rubber latex is about 0.15 to about 0 by weight.
. It has a particle size of 8 microns, preferably 0.3 microns. In terms of composition, the rubber phase is polybutadiene, styrene-butadiene copolymer, butadiene-acrylonitrile copolymer, polyisoprene, EPM (ethylene / propylene rubber), EPD
M rubber (hexadiene as the diene - (1,5) or ethylene / propylene / diene rubber containing a small amount of nonconjugated diene such as norbornadiene) a, and C ₁ -C ₈ alkyl acrylate (especially ethyl acrylate, butyl acrylate and ethylhexyl acrylate) It may be composed mainly of a crosslinked alkyl acrylate rubber. About 10 to 90% by weight of a resin grafted on one or more rubbers and about 90%
% Can also be used. At the end of the polymerization, destroy the latex emulsion,
Collect ABS. In bulk polymerization, the polymerization is carried out in styrene / acrylonitrile monomer rather than in water. Instead of synthesizing the rubber, the rubber prepared beforehand is dissolved in the monomer liquid. Next, the rubber-monomer solution is supplied to a reactor to perform grafting / polymerization. When made by the bulk or bulk-suspension process, the soluble rubber ranges from about 5 to 25% by weight and the dispersed rubber phase has a diameter of about 0.5 to about 10 microns. The percentage by weight of free SAN phase present increases with the amount of rubber used.

Instead of the styrene monomer and acrylonitrile monomer used for the grafted or ungrafted resin, α-methylstyrene, p-methylstyrene,
Mono-, di- or tri-halostyrene, alkyl methacrylate, alkyl acrylate, maleic anhydride, methacrylonitrile, maleimide, N-alkylmaleimide, N-arylmaleimide, or alkyl- or halogen-substituted N
Monomers such as arylmaleimides may be used instead of or in addition to styrene or acrylonitrile. As in the bulk method, rubber dissolved in a monomer solution is used in suspension polymerization, but after polymerizing SAN to a low degree of polymerization, rubber / SAN
/ The monomer mixture is suspended in water to complete the polymerization.

SAN Copolymer The SAN copolymer component of the composition of the present invention comprises one or more SAN copolymers. Conventional SAN copolymers have an oligomer content of about 0.1 to about 10% by weight.
Here, the oligomer can be generally defined as a SAN component having a molecular weight of about 15,000 g / mol or less. More generally, oligomers have a molecular weight of about 10,000 g.
/ Mol or less.

Preferred SAN copolymers have a relative weight average molecular weight of about 40,000 to about 11,000.
0 g / mol, more preferably 50,000 to about 90000 g / mol, and even more preferably about 60,000 to about 85,000 g / mol SAN, where the molecular weight is determined by gel permeation chromatography against polystyrene standards of narrow dispersity. Measured. SAN copolymers typically contain about 10-40%, preferably 15-35%, more preferably 20-30% by weight of acrylonitrile, the balance being styrene.

The inventors can reduce the notched Izod ductile-brittle transition temperature by removing at least some of the low molecular weight side of the distribution (ie, at least some of the oligomer content) from the initially polymerized SAN. (This indicates an improvement in ductility). Except for at least some of the low molecular weight side of the distribution, the viscosity of the blend increases only slightly. Thus, the resulting viscosity-ductility balance is very favorable. Further, by selecting the amount of oligomer removed, the polycarbonate / ABS / SAN blend can be finished to have an acceptable blend viscosity while obtaining a product with a wide range of properties. Also, removing the low molecular weight side of the distribution increases the Tg (and HDT) of the blend. Such Tg (and HD
The increase in T) cannot be achieved simply by increasing the molecular weight of SAN.

Reduction of the content of low molecular weight substances (ie, styrene-acrylonitrile oligomers) in the styrene-acrylonitrile copolymer component of the composition of the present invention may be achieved in any suitable manner.

In a preferred embodiment, the oligomer content of the SAN copolymer component of the present invention is reduced by chemical fractionation. Suitable chemical fractionation techniques are well-known in the art.

In a preferred chemical fractionation technique, the SAN copolymer is dissolved in a first solvent, such as methyl ethyl ketone, in which the high molecular weight SAN copolymer species and the low molecular weight SAN oligomer species dissolve, and then the high molecular weight SAN copolymer is dissolved. A second solvent, such as isopropanol or methanol, where the coalesced species becomes relatively insoluble, is added to the solution with mixing at a rate slow enough to prevent precipitation of the high molecular weight SAN copolymer species. The resulting mixture is
Separate into layers (ie, a first solvent layer and a second solvent layer) and isolate the fractionated high molecular weight SAN copolymer species from the first solvent layer by further adding a second solvent. I do.

One preferred method of removing the oligomer content is chemical fractionation, but the invention is not limited thereto. Other methods may be used to eliminate the oligomer content, and the present invention includes such methods. Further, the oligomer content may be omitted at any time. That is, before blending with the polycarbonate component, the oligomer is SAN
The oligomer may be removed from the components, the oligomer may be removed after blending, or the oligomer may be removed both before and after blending.

Other Ingredients In addition, the resin composition of the present invention may contain certain additives such as an antistatic agent, a filler, a pigment, a dye, an antioxidant, a heat stabilizer, and an ultraviolet absorber. Agent, lubricant,
There are flame retardants and other additives commonly used in polycarbonate / ABS / SAN blends.

Suitable antistatic agents that may be incorporated as an optional component into the resin blend of the present invention include, but are not limited to, a polyethylene oxide block polymer and epichlorohydrin, polyurethane, polyamide, polyester or polyetheresteramide. There are reaction products.

Suitable fillers that may be optionally included in the resin blend of the present invention include, but are not limited to, talc, glass fiber, calcium carbonate, carbon fiber, clay, silica, mica, and conductive metals. .

The resin blend of the present invention may contain an appropriate release agent as an optional component. The product of the present invention may be obtained by mixing the components of the composition of the present invention under conditions suitable for forming a blend of the components, such as by melt mixing in a twin-roll mill, Banbury mixer or single or twin screw extruder. And optionally the composition thus obtained may be in particulate form, for example by pelletization or grinding.

The blends of the present invention can be formed into useful products by various means such as injection molding, extrusion, rotational molding, blow molding and thermoforming, for example, housings for computers and office equipment, household appliances, and the like. it can.

Various embodiments of the present invention are illustrated in the following examples. However, these examples are illustrative and do not limit the technical scope of the present invention defined in the claims.

[0049]

【Example】

The following abbreviations are used in the examples. PC-1: a linear polycarbonate resin having an absolute weight average molecular weight of about 29000 g / mol. PC-2: a linear polycarbonate resin having an absolute weight average molecular weight of about 24000 g / mol. ABS: Acrylonitrile-butadiene-styrene graft copolymer containing about 50% by weight butadiene and 50% by weight styrene-acrylonitrile copolymer (75% by weight styrene and about 25% by weight acrylonitrile). SAN-1: 75% by weight of styrene having a relative weight average molecular weight of about 62600 g / mol
And a copolymer of acrylonitrile and 25% by weight. SAN-2: SAN-1 having a relative weight average molecular weight of about 66600 g / mol with an oligomer content of about 3.5% by weight removed by chemical fractionation. SAN-3: SAN-1 having a relative weight average molecular weight of about 71500 g / mol with an oligomer content of about 7.0% by weight removed by chemical fractionation. SAN-4: a copolymer of about 75% by weight of styrene and 25% by weight of acrylonitrile with a relative weight average molecular weight of about 87600 g / mol.

Examples 1 and 2 and Comparative Examples C1 and C2 In each of the blends of Examples 1 and 2 and Comparative Examples C1 and C2 of the present invention, the components shown in Table I were used in the relative amounts indicated (each in parts by weight) By mixing. Blends containing the components shown in Table I were prepared by blending each component with a Henschel mixer for about 1 minute, and then the blend was added to the hopper of the extruder. In a typical small laboratory experiment, a 6 barrel Welding Engineers 20
These blends were melted at 320-400 rpm with a melt temperature of about 5
Compounded at 50 ° F. 28 tons of compounding material Eng
Injection molding was performed at about 525 ° F. using an el molding machine. Unless otherwise specified, specimens were 3.
It was 2 ± 0.2 mm. Notched Izod impact was measured according to the ASTM D256 test method. Notched Izod data was collected over a given temperature range. Ductile / brittle temperature was determined as the temperature at which the impact energy was below 8 ft-lb / in.

[0051] The viscosity of the sample was determined using a getfeld capillary rheometer (Goettfe).
rt Capillary Rheometer). The viscosity is
Measured at about 550 ° F. at a frequency of about 100 to about 6300 Hz.

The absolute weight average molecular weight of the polycarbonate resin was determined by gel permeation chromatography against an absolute molecular weight polycarbonate standard.

SAN-1 and SAN-4 are conventional grade SANs. SAN-2 is S
An AN-1 type SAN was prepared by dissolving about 300 grams of SAN in about 1.5 liters of methyl ethyl ketone and dropping about 2.1 liters of isopropanol dropwise while stirring the solution. The addition of isopropanol was slow enough so that the polymer did not precipitate. The mixture was left for about 1 hour. The upper layer was decanted and concentrated to dryness, leaving about 10.5 grams of residue. The lower layer dissolved polymer was precipitated by slow addition to methanol in a blender. The precipitate was filtered and dried in a vacuum oven at about 40 ° C. overnight and then at 80 ° C. for several days.

SAN-3 has about two SAN-1 type SANs in the same manner as the manufacture of SAN-2.
Take 50 grams and dissolve it in about 1.25 liters of methyl ethyl ketone,
It was prepared by dropwise addition of about 1.3 liters of isopropanol. SAN
SAN-2 was made using the same procedure used to make -3.

For each composition, the blend viscosity, notched Izod ductility / brittle transition results, Tg of the polycarbonate phase, and HDT are shown in Table I below.

[0056]

[Table 1]

The above Examples 1-2 and Comparative Examples C1-C2 were made of polycarbonate / ABS / SA
Demonstrating that removing at least some of the oligomer distribution from the SAN component of the N blend can provide an attractive notched Izod ductile / brittle transition temperature while maintaining relatively low blend viscosity.

Although the above description is of specific disclosure, those skilled in the art can make various modifications to the above disclosure, and all such modifications are considered to be within the scope of the appended claims. Should.

[Procedural Amendment] Submission of translation of Article 34 Amendment of the Patent Cooperation Treaty

[Submission date] August 9, 2000 (200.8.9)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

────────────────────────────────────────────────── ─── Continuing the front page (72) Inventor Langarajan, Platinum, United States, 12065, Clifton Park, New York, Dyer Driver, No. 2 (72) Inventor Urokjinski, Ronald James United States of America, 12303, New York State, Schenecta Day, Vinsenza Lane, No. 209 F term (reference) 4F071 AA12X AA22 AA22X AA34X AA50 AA77 AA81 AG01 BA01 BB05 BB06 BC07 4J002 BC063 BN15X CG00W CG01W CG02W

Claims (18)

[Claims] 1. A thermoplastic resin composition comprising (a) an aromatic polycarbonate resin, (b) an acrylonitrile-butadiene-styrene graft copolymer, and (c) a styrene-acrylonitrile copolymer having a reduced oligomer content. . 2. The composition of claim 1, wherein the oligomer content of the styrene-acrylonitrile copolymer has been reduced by chemical fractionation. 3. The method according to claim 1, wherein the styrene-acrylonitrile copolymer has a molecular weight of about 40,000 or more.
The composition of claim 1 having a weight average molecular weight of about 110,000 g / mol. 4. The method according to claim 1, wherein the styrene-acrylonitrile copolymer is about 50,000-
The composition of claim 3 having a weight average molecular weight of about 90000 g / mol. 5. The method according to claim 1, wherein the styrene-acrylonitrile copolymer is about 60,000 or more.
The composition of claim 4, having a weight average molecular weight of about 85,000 g / mol. 6. The method according to claim 1, wherein the aromatic polycarbonate resin has a content of about 10,000 to about 200.
The composition of claim 1 having a weight average molecular weight of 000 g / mol. 7. The composition according to claim 6, wherein said aromatic polycarbonate resin comprises two or more aromatic polycarbonate resins. 8. The method according to claim 1, wherein the aromatic polycarbonate resin has a weight average molecular weight of about 29.
7. The composition according to claim 6, comprising 000 g / mol of aromatic polycarbonate resin. 9. The aromatic polycarbonate resin has a weight average molecular weight of about 24.
7. The composition according to claim 6, comprising 000 g / mol of aromatic polycarbonate resin. 10. The composition of claim 1, wherein the thermoplastic resin composition comprises from about 4 to about 59 parts by weight, based on 100 parts by weight of the composition, of an acrylonitrile-butadiene-styrene copolymer. 11. The composition of claim 1, wherein the thermoplastic resin composition comprises from about 5 to about 46 parts by weight, based on 100 parts by weight of the composition, of an acrylonitrile-styrene copolymer. 12. The acrylonitrile-styrene copolymer comprises about 10 to about 40% by weight acrylonitrile and about 60 to about 40% by weight, based on the total weight of the copolymer.
The composition of claim 11, comprising about 90% by weight styrene. 13. A method for blending a thermoplastic resin composition, comprising blending an aromatic polycarbonate resin, an acrylonitrile-butadiene-styrene graft copolymer, and a styrene-acrylonitrile copolymer having a reduced oligomer content. 14. The method of claim 13, wherein the oligomer content of the styrene-acrylonitrile copolymer has been reduced by chemical fractionation. 15. The method according to claim 15, wherein the styrene-acrylonitrile copolymer is about 40,000.
14. The method of claim 13, having a weight average molecular weight of from about to about 110,000 g / mol. 16. The method according to claim 16, wherein the styrene-acrylonitrile copolymer is about 50,000.
14. The method of claim 13, having a weight average molecular weight of from about 90000 g / mol. 17. The method according to claim 17, wherein the styrene-acrylonitrile copolymer is about 60,000.
14. The method of claim 13, having a weight average molecular weight of from about 85,000 g / mol. 18. An article formed from the thermoplastic resin composition according to claim 1.