WO2002036688A2

WO2002036688A2 - Pc/asa composition having improved notched izod and reduced gate blush

Info

Publication number: WO2002036688A2
Application number: PCT/US2001/032494
Authority: WO
Inventors: Albin P. Berzinis; Jean R. Pierre
Original assignee: General Electric Company
Priority date: 2000-10-30
Filing date: 2001-10-17
Publication date: 2002-05-10
Also published as: WO2002036688A3; AU2002213366A1

Abstract

A thermoplastic composition having reduced gate blush comprises: a polycarbonate; an acrylonitrile-butylacrylate-styrene resin; and a high molecular weight acrylic copolymer processing aid. The high molecular weight processing aid is an acrylic copolymer, preferably selected from the group consisting of styrene-acrylonitrile, methylmethacrylate-butylmethacrylate, methylmethacrylate-ethylacrylate, and butylmethycrylate-methacrylate copolymers.

Description

PC/ ASA COMPOSITION HAVING IMPROVED NOTCHED IZOD AND

REDUCED GATE BLUSH

Field of the Invention

The present invention relates to thermoplastic compositions comprising a blend of polycarbonate , a grafted emulsion rubber with a glass transition temperature of less than 0 °C and a mean particule size of 50-1000 ran, preferably 50-600nm , which can be a graft acrylonitrile-butylacrylate- styrene (ASA) resin, a graft acrylonitrile-butadiene-styrene (ABS) resin or a graft acrylonitrile-(ethylene-proρylene-diene)-styrene (AES) resin, one or two amorphous non crosslinked linear copolymers such as SAN, AMSAN, PMMA or MMA-SAN and further containing a gate blush reducing component selected from the group consisting of high molecular weight polymers consisting of copolymers of styrene-acrylonitrile or alkylacrylates.

Background of the Invention

There are many references in the prior art to blends of polycarbonate and ABS, the first significant patent reference in this field being the Grabowski U.S. Pat. No. 3,130,177. There are also many references in the prior art to blends of polycarbonate and ASA to improve weathering properties. As improvements on the original Grabowski patent were developed, attention was focussed on the weld line strength problem, which characterized certain of these blends. In the Margorte et al. U.S. Pat. No. 3,988,389, the weld line strength of a polycarbonate/ ABS blend is said to be improved by using a very specific graft ABS formulation having a narrowly defined graft ratio, rubber particle size, rubber content, and the like.

Insofar as the use of poly (alkyl methacrylates) in rubber modified polycarbonates is concerned, British Patent 1,182,807 describes a blend of athermoplastic aryl polycarbonate and a poly(methylmethacrylate) which may optionally include a minor proportion of a "rubbery polymeric material." Examples of the latter "rubbery polymeric material "include SBR and nitrile rubbers as well as graft polymers, primarily rubbery acrylate copolymers. Graft ABS, and more particularly, high rubber graft/ styrene-acrylonitrile

(SAN) blends are not mentioned or suggested.

Weatherable thermoplastic compositions based on poly(butyI acrylate) rubbers grafted with styrene-acrylonitrile (ASA) are currently used for exterior automotive parts such as mirror housings, wind deflectors, front grills etc. Polycarbonate (PC)/ ASA blends provide long term heat resistance with good weathering characteristics. Because major applications are for unpainted exterior parts, aesthetics is very critical. Polymer blends based on PC often suffer from a "gate blush" defect, which is manifested as a dull zone on the surface of the part adjacent to the gate. The severity of this effect is somewhat dependent on the design of the gating into the part and also upon the shear stress applied during the injection molding process. This suggests that this defect is related to the distortion of the complex blend morphology during the injection process through the effect of the melt rheology of the individual blend components.

Summary of the Invention

The present invention relates to the use of high molecular weight processing aid polymers (SAN copolymers, Acrylic copolymers) to produce weatherable molded parts with good aesthetics, low gate blush, improved notched Izod impact characteristics and good property retention under long term thermal aging or weathering.

In the present invention, it has been discovered that the use of up to about 5 per cent by weight of a high weight average molecular weight acrylic or styrene-acrylonitrile copolymer, has a dramatic effect on the gate blush and improves the notched Izod impact of blends of polycarbonate, such as bisphenol A polycarbonate, and graft polymers of acrylate styrene acrylonitrile (ASA), acrylonitrile-butadiene-styrene (ABS) or acrylonitrile- (ethylene-propylene-diene)-styrene (AES), preferably those graft polymers formulated with a high rubber graft and a rigid phase comprising one or two amorphous non crosslinked linear copolymers such as SAN, AMSAN, PMMA or MMA-SAN.

A composition having reduced gate blush and an improved notched Izod is provided for by a thermoplastic composition comprising: a) polycarbonate; b) a grafted rubber preferably with a glass transition temperature of less than 0 °C and preferably with a mean particule size of 50-1000 ran, preferably 50-600nm , which can be a graft acrylonitrile- butylacrylate-styrene (ASA) resin, a graft acrylonitrile-butadiene- styrene (ABS) resin or a graft acrylorutrile-(ethylene-propylene- diene)-styrene (AES) resin and a rigid phase comprising one or two amorphous non crosslinked linear copolymers such as SAN, AMSAN, PMMA or MMA-SAN; and c) a high molecular weight acrylic copolymer processing aid.

Detailed Description of the Invention

As mentioned above in the summary portion of this Specification, the present invention relates generally to blends of ASA copolymer with polycarbonate, which blends further contain up to about 5 % by weight (based on the end product) of a high weight average molecular weight acrylic copolymer. As used herein when the phrase "up to about" is used in conjunction with a maximum amount and no specifically stated minimum amount the phrase should be taken to mean "from slightly greater than zero up to about."

The ASA comprises an acrylic monomer such as acrylonitrile, substituted acrylonitrile, and/ or an aery He acid ester, exemplified by alkyl acrylates such as ethyl acrylate and methyl methacrylate.

Examples of the cyano-containing alkenyl nitrile monomers include acrylonitrile, ethacrylonitrile, methacrylonitrile, alpha -chloroarylonitrile, beta -chloroacrylonitrile, alpha -bromoacrylonitrile, and beta -bromoacrylonitrile, while examples of the acrylic acid esters include methyl acrylate, alkyl methacrylate, ethyl acrylate, butyl acrylate, propyl acrylate, isopropyl acrylate and mixtures thereof. The preferred acrylic monomer is an alkenyl nitrile, particularly acrylonitrile. In a further preferred embodiment, the grafting monomers which form the ASA resin are essentially free of methylmethacrylate, i.e., the grafting monomers containing less than about 5 weight percent methyl methacrylate.

Generally the acrylate styrene acrylonitrile (ASA) component of the composition of the present invention is produced by a process that comprises the steps of emulsion polymerizing at least one alkyl acrylate monomer in the presence of from about 0.05% to about 10% by weight of a polyfunctional crossliriking monomer to form an aqueous latex of crosslinked acrylic elastomer particles, thereafter emulsion polymerizing a charge of styrene and acrylonitrile monomers in the presence of a crossliriking agent and the crosslinked latex particles to crosslink the styrene acrylonitrile charge, and thereafter adding a monomeric charge of styrene and acrylonitrile which does not contain a crossliriking agent but which does contain an initiator to polymerize the monomers and form a linear styrene-acrylonitrile polymer. The final product that is formed has impact and weather resistance and comprises from about 10 to 50% by weight of the crosslinked aery He elastomer, from about 5 to 35% by weight of the crosslinked styrene- acrylonitrile copolymer surrounding and penetrating the crosslinked acryHc elastomer, and from about 15 to 85% by weight of the polymerized linear styrene acrylonitrile.

In greater detail, now, the elastomer particles that are utilized in preparing the particles of this invention are made by means of conventional aqueous emulsion procedures well known to those skiUed in the art of using emulsifiers and water-soluble catalysts.

Thus, in conducting the aqueous emulsion polymerization step leading to the preparation of these elastomer particles, there is preferably first prepared a monomer charge comprising an aqueous emulsion containing about 10 to 50%, by weight, of one or more monomers, the identity of which will be described in detail hereinbelow, and from 0.2 to 2.0% by weight of a suitable emulsifier. From about 0.05 to 2.0% by weight of the monomer mixture, of a water-soluble catalyst, such as ammonium, sodium or potassium persulfate, hydrogen peroxide or a redox system, such as a mixture of a persulfate with an alkaH metal bisulfite, thiosulfate or hydrosulfite, is introduced, and the mixture is then heated at a temperature of from about 40° to 95°C for a period of about 0.5 to 8 hours.

The acrylic elastomer particles used in preparing the particles of this invention comprise crosslinked acrylic polymers or copolymers having a Tg, i.e., a glass transition temperature, of less than about 25°C which can be polymerized by means of free radical initiated emulsion techniques. These acryHc elastomer particles should be crosslinked so that they can retain their size and shape during subsequent polymer processing steps. This crossHnking can be achieved during the polymerization of the elastomer if a polyfunctional ethylenically unsaturated monomer is included in the polymerization recipe. As used in this disclosure, the term "crossHnked" denotes a polymer that at ambient temperatures is substantially insoluble in such organic solvents as tetrahydrofuran or cyclohexanone.

Examples of acrylic elastomers that can be used include the crosslinked polymers of the C2-C10 alkyl acrylate and the C.8-C22 alkyl methacrylate monomers, preferably the Gi-Cδ alkyl acrylates, such as poly(n-butyl acrylate),poly(ethyl acrylate) and poly(2-ethyl hexylacrylate). At least one acrylate monomer is utilized in this step. If desired, the monomer charge may contain smaU amounts, i.e., 1% to 20% by weight of the amount acrylate monomer, of optional monomers including styrene, acrylonitrile, methacrylonitrile, methyl methacrylate, mefhacryHc acid, acryHc acid, vinylidene chloride, vinyl toluene and any other ethylenically unsaturated monomer copolymerizable with the acrylate monomer selected for use.

In order to crosslink the acrylate monomer from about 0.05 % to about

10% by weight (preferably 0.1% to 5%) based on the weight of acrylate monomer, of at least one crosslinking agent is used. This crosslinking agent is for the purposes of this composition a di- or poly-functional ethylenicaUy unsaturated monomer having at least one vinyl group. As is weH known in the art the vinyl groups on the crosslinking monomer can be the same (e.g. divinyl benzene, trimethylol propane triacrylate, etc.) or different, (e.g., allyl methacrylate, diallyl fumarate, diaHyl maleate, etc.) Examples of other suitable crosslinking monomers which are known to persons in the art and which can be used are 1,3-butylene dimethacrylate, diethylene glycol dimethacrylate, ethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, ethylene bisacrylamide, diethylene glycol diacrylate, ethylene glycol diacrylate, divinyl ether, diaUyl phthalate, divinyl sulf one, divinyl sorbitol, triethylene glycol dimethacrylate, trimethylene glycol diacrylate, butylene glycol diacrylate, pentamethylene glycol diacrylate, glyceryl triacrylate, octylene glycol diacrylate, trimethylolpropane triacrylate, the tetra-acrylate ester of pentaerythritol and various diallyl phosphonates.

Optimum results are obtained by the use of a crosslinked copolymer containing from about 95 to 99.9% by weight of n-butyl acrylate and from about 0.1 to 5%, by weight, of butylene glycol diacrylate.

The emulsifier which is used is at least one of the f oHowing conventional types: an anionic emulsifier, e.g., the _- n carboxyHc acids, the sulfates or, sulfonates, of C6-C22 alcohols or alkyl phenols; a non-ionic emulsifier, e.g., the addition products of alkylene oxides to fatty acids, amines or amides; a combination of the foregoing anionic and non-ionic emulsifiers; or the cationic emulsifiers, e.g., a quaternary ammonium containing compound. The amount of emulsifier should be present from about 0.5% to about 5% by weight in the emulsion.

Moreover, in a preferred embodiment of the process of this invention, it has been found that regardless of the particular emulsifier being utilized in preparing the rubber polymer latex, its polymerization in large scale commercial equipment is greatly f aciHtated by introducing the monomer charge to the system in several portions over a period of from 1 to 3 hours. Thus, where this is not done and the total monomer charge is introduced in one portion, the resulting exothermic polymerization reaction often becomes virtually uncontroHable leading to overheating which, in turn, may set up, i.e., coagulate, the resulting polymer latex. However, by dividing the monomer charge and introducing it in about several portions, the resulting polymerization reaction remains controHable and overheating and coagulation can be prevented. An initiator is also present in the emulsion in an amount ranging from about 0.005% to 2% by weight of the acrylate monomer. Suitable for use are water-soluble peroxide compounds, e.g., hydrogen peroxide and alkaH metal and ammonium persulfates, oil soluble organic peroxides and azo compounds, e.g., benzoyl peroxide, azo-bis-isobutyronitrile and the like, used singly or in combination. Redox catalysts, e.g., mixtures of peroxide catalysts with reducing agents, such as hydrazine, alkali metal bisulfites, thiosuHates, and hydrosulfites, and soluble oxidizable sutfoxyl compounds can also be used.

A chain transfer agent such as an alkyl mercaptan, e.g., t-dodecyl mercaptan, toluene, xylene, chloroform, halogenated hydrocarbons and the Hke may also be used.

A buffer to keep the pH at 7.0 or higher is a final component of the emulsion.

The next step in the preferred embodiment of preparing the ASA polymer used in the compositions of the present invention is the emulsion polymerization of a mixture of styrene and acrylonitrile in the presence of a minor portion of at least one difunctional or polyfunctional crosslinking monomer to form a crosslinked styrene-acrylonitrile polymer. This emulsion polymerization is carried out in the presence of the crosslinked acryHc elastomer by adding the st rene-acryolonitrile charge to the previously prepared aqueous emulsion of crosslinked acrylate elastomer. The amount of styrene-acrylonitrile which is added ranges from 5 to 35% of the weight of the final product that wϋl be produced whereas the crosslinked acrylate elastomer is present from about 10% to 50% based upon the weight of the final product which will be formed. The monomer charge of styrene-acrylonitrile can comprise from about 50/50 to 85/15 weight parts of styrene to acrylonitrile with the preferred ratio being 76/24. If desired, minor amounts e.g., below about 20% by weight, of optional monomers can be included. Examples are t-butyl styrene, p- chlorostyrene, alpha -methyl styrene, methyl methacrylate, alkyl acrylate, vinylidene chloride, ethylene, propylene, isobutylene and other ethylenicaUy unsaturated compounds copolymerizable with styrene and acrylonitrile.

The crosslinking agent, emulsifiers, initiators and chain transfer agents discussed in the previous step can also be used in this step in the same amounts to form the crosslinked styrene-acrylonitrile on crosslinked acrylate elastomer.

If desired, the two steps described above may be reversed in sequence.

After the emulsion polymerization of the crosslinked styrene- acrylonitrile polymer onto the crosslinked acrylic elastomer or the reverse sequence of these two steps has been accompHshed, the final step of the present invention is performed. This is the formation of a linear styrene- acrylonitrile polymer which is not substantially grafted onto the crosslinked acryHc elastomer-crosslinked styrene-acrylonitrile copolymers. The amount of linear styrene-acrylonitrile polymer which is grafted is less than 30 weight percent, preferably less than 20 weight percent. This third step may be accompHshed by either suspension or emulsion polymerization of a charge of styrene and acrylonitrile monomers having the same general composition as the styrene and acrylonitrile charge used in the previous step in the absence of a crossHnking monomer. The combined amounts of styrene and acrylonitrile utilized in this step wiU vary from 15-85% by weight of the final product. The same emulsifiers, initiators, chain transfer agents and optional monomers utilized in previous steps may be used in this final polymerization procedure.

If suspension polymerization is chosen the suspending agent can be methyl ceUulose, hydroxyethyl cellulose, hydroxypropyl ceHulose, carboxymethyl ceUulose, talc, clay, polyvinyl alcohol, gelatin and the Hke.

Preferred for this purpose is hydroxypropyl methyl ceUulose which should, preferably, have a viscosity of at least about 3,000 and, preferably, about 15,000 cps. As determined, at 20 °C, with a 2%, by weight, aqueous solution of the polymer in an Ubbelohde viscometer according to ASTM Procedures D- 1347-64 and D-2363-65T.

Other additives can be used in forming the linear styrene-acrylonitrile matrix to confer desired properties upon the final product. Included are

conventional Hght, thermal and ultraviolet Hght stabilizers, antioxidants, dyes, pigments, mineral additives and fillers and reinforcing fillers.

Polycarbonates are a special class of polyesters derived from the reaction of carbonic acid derivatives with aromatic, aHphatic, or mixed diols. They may be produced by the reaction of phosgene with a diol in the presence of an appropriate hydrogen chloride receptor or by a melt transesterification reaction between the diol and a carbonate ester. Polycarbonate can be made from a wide variety of starting materials, however, the principal polycarbonate produced com erciaUy is bisphenol A polycarbonate, a polycarbonate made by reacting bisphenol A with phosgene by condensation.

For a more complete discussion of the chemistry of polycarbonates, one may refer to The irk-Othmer Encyclopedia of Chemical Technology, Third Edition (1982), Vol. 18, pp. 479-494. The article contained therein by D. W.

Fox is incorporated herein by reference in its entirety. Polymethylmethacrylate (PMMA) is produced by the polymerization of methyl methacrylate monomer, and may be derived by (1) the reaction of acetone cyanohydrin, methanol and sulfuric acid or (2) the oxidation of tert- butyl alcohol to methacrolein and then to methacryHc acid foUowed by the esterification reaction with methanol. PMMA homopolymer exists in its pure form only theoretically and is generaUy avaUable commerciaUy as a mixture of the homopolymer and various copolymers of methyl methacrylate and Ci- d alkyl acrylates, such as ethyl acrylate.

Preferably, the compositions according to the present invention contain from about 5 to about 95 weight percent polycarbonate, preferably from about 10 to about 90 weight percent polycarbonate, more preferably from about 20 to about 80 weight percent polycarbonate, and most preferably from about 25 to about 75 weight percent polycarbonate; from about 5 to about 70 weight percent ASA copolymer, preferably from about from about 10 to about 60 weight percent ASA copolymer, more preferably from about 15 to about 40 weight percent ASA copolymer and most preferably from about 12 to about 30 weight percent ASA copolymer; and from about 1 to about 10 weight percent processing aid, preferably from about 1.5 to about 8 weight percent processing aid, more preferably from about 2 to about 7 weight percent processing aid and most from about 2.5 to about 6 weight percent processing aid where the processing aid is a high weight average molecular weight acryHc copolymer selected from the group consisting of styrene-acrylonitrile, methylmethacrylate-butylmethacrylate, methylmethacrylate-ethylacrylate, and butylmethacrylate-methacrylate .

The weight average molecular weight (measured by GPC of solutions in chloroform using a calibration curve based on analysis of monodisperse fractions of reference polystyrene of known molecular weight) of the processing aid is above 400K daltons, preferably above 500K daltons, more preferably above 550K daltons and most preferably above 600K daltons. This invention has been described in connection with certain specific embodiments, but it should not be Hmited to the specific embodiments described herein.

Examples

An ASA was prepared by emulsion polymerization from a crosslinked butylacrylate (BA) rubber of broad particle size distribution (from 50 run to 1000 m, preferably from 50 to 700 nm) to which was grafted SAN (the AN composition in copolymer from 15 to 35%, preferably from 25 to 30%) to a final BA content of 30-70%, preferably from 45-60% . Blends with

Polycarbonate were obtained by first dry blending Polycarbonate powder with ASA powder, SAN suspension beads, high molecular weight processing aid powder and appropriate additives in a high speed mixer (Henschel or Papenmeier), followed by extrusion through a co-rotating intermeshing twin- screw extruder using a temperature profile from 200 to 260C. The granulated products so obtained were molded using a multicavity ISO tool using melt temperature varying from 250C to 260C and a mould temperature around 60C.

The foUowing processing aids were evaluated:

Blendex 869: SAN copolymer; Mw(*)=610K (GE-Specialty Chemicals)

Metablen P552: Methylmethacrylate-butylacrylate copolymer; Mw(*)=930K (ATO)

Paraloid K120N: Methylmethacrylate-ethylacrylate copolymer; Mw (*)=720K(Rohm and Haas) Kane Ace X210: Methylmethacrylate-butylacrylate copolymer; Mw(*)=830K(Kaneka)

Typical resin compositions comprise:

(i) 50-90 % polycarbonate (Mw(*)=25,000 to 200,000);

(u) 10-40% grafted polybutylacrylate rubber;

(Hi) 0-40% SAN copolymer (Mw(*)=60,000 to 300,000)

(iv) 2.5-5% High molecular weight processing aid (Mw(*)=400,000 to 1,500,000) based on SAN or AcryHc copolymers.

(v) Lubricants, antioxidants and light stabiHsers

(vi) FiUers, pigments and dyes

(*) Mw measured by GPC in Chloroform using monodisperse polystyrene calibration.

Performed experiments:

The tables 1 and 2 show results obtained on PC/ ASA blends containing 60 phr (parts per hundred parts resin) and 72 phr Polycarbonate and modified with 3.5phr of Blendex 869 SAN, Metablen P552, Paraloid K120N and Kane Ace X210 AcryHc processing aids. Data of formulations containing no processing aid are also given for comparison.

It appears that both SAN and Acrylic processing aids improve the gate. Addition of processing aids also increases the notched Izod impact of the blends. Moreover, aH other properties are retained. TABLE 1

TABLE 2

Table 3 shows that the same conclusions apply to PC/ ASA blends based on 45 phr Polycarbonate and 5 phr of aU four high molecular weight processing aids considered. The data indicate also that more than 2.5phr are required to completely remove the gate blush. It is important to note that an important die swell was observed during compounding for aU compositions containing high molecular weight processing aids.

To test whether bulk melt rheology alone is responsible for the effect of these processing aids on gate blush we compared the effects of the Metablen P-552 and Blendex 869 to that of a dispersion of UHMW Teflon in SAN. The Teflon is commonly added as an anti-drip agent in flame-retardant PC blends and is well known to cause substantial die swell when the blend formulations are extruded or injection molded. The blends described in Table 3 (45% PC, 25% ASA, medium grey pigment) were prepared as described above via extrusion compounding and then were injection-molded into ASTM test specimens. The test result units have been translated into ISO units for more convenience. The results show that while the Teflon additive did result in substantial die sweU, it was ineffective in either eliminating gate blush or in improving the notched Izod impact strength of the ASA/PC blends. The beneficial actions of the preferred process aids in ASA/ PC blends can not be anticipated from their effect on melt rheology alone.

TABLE 3

Mod= moderate

TABLE 4

The improvement in aesthetics and impact characteristics is also observed when SAN is prtly replaced by PMMA or when the ASA rubber is replaced by ABS rubber . The blends described in table 4 were prepared as described above via extrusion compounding and injected into ISO test specimens. The data show that the high MW acryHc processing aid is also effective in eliminating gate blush and increasing the notched izod impact of both types of formulation.

Claims

CLAIMSHaving described the invention that which is claimed is:

1. A thermoplastic composition comprising: a. polycarbonate; b. acrylonitrUe-butylacrylate-styrene resin; and c. a high molecular weight acryHc copolymer processing aid.

2. The composition of claim 1 wherein the notched Izod is at least 50 KJ/m².

3. The composition of claim 1 wherein the high molecular weight acryHc copolymer processing aid is an acryHc copolymer selected from the group consisting of styrene-acrylonitrile, methyHnethacrylate-butyhnethacrylate, methylmethacrylate-ethylacrylate, and butylmethacrylate-methacrylate copolymers.

4. The composition of claim 3 wherein the polycarbonate is present in an amount ranging from about 5.0 to about 95.0 weight percent, the acrylonitrUe-butylacrylate-styrene resin is present in an amount ranging from about 5.0 to about 70.0 weight percent and the high molecular weight acrylic copolymer processing aid is present in an amount ranging from sHghtly greater than zero up to about 5.0 weight percent.

5. The composition of claim 4 wherein the high molecular weight acryHc copolymer processing aid is a styrene-acrylonitrile copolymer.

6. The composition of claim 4 wherein the high molecular weight acryHc copolymer processing aid is a rneti ylmethacrylate-butyhnethacrylate copolymer.

7. The composition of claim 4 wherein the high molecular weight acrylic copolymer processing aid is a methylmethacrylate-ethylacrylate copolymer.

8. The composition of claim 4 wherein the high molecular weight acrylic copolymer processing aid is a butylmethacrylate-methacrylate copolymer.

9. The composition of claim 4 where the weight average molecular weight of the high molecular weight acryHc copolymer processing aid is above 400K daltons.

10. The compositoin of claim 5 where the weight average molecular weight of the high molecular weight acrylic copolymer processing aid is above

400K daltons.

11. A thermoplastic composition consisting essentiaUy of: a. polycarbonate; b. an aery lonitrile-butylacrylate-styrene resin; and c. a high molecular weight acryHc copolymer processing aid.

12. The composition of claim 11 wherein the notched Izod is at least 50 KJ/m*.

13. The composition of claim 11 wherein the high molecular weight acryHc copolymer processing aid is an acryHc copolymer selected from the group consisting of styrene-acrylonitrUe, methyknethacrylate- butylmethacrylate, methylmethacrylate-ethylacrylate, and butylmethacrylate-methacrylate copolymers.

14. The composition of claim 13 wherein the polycarbonate is present in an amount ranging from about 5.0 to about 95.0 weight percent, the acrylonitrile-butylacrylate-styrene resin is present in an amount ranging from about 5.0 to about 70.0 weight percent and the high molecular weight acryHc copolymer processing aid is present in an amount ranging from slightly greater than zero up to about 5.0 weight percent.

15. The composition of claim 14 wherein the high molecular weight acryHc copolymer processing aid is a styrene-acrylonitrile copolymer.

16. The composition of claim 14 wherein the high molecular weight acryHc copolymer processing aid is a methylmethacrylate-butylmethacrylate copolymer.

17. The composition of claim 14 wherein the high molecular weight acryHc copolymer processing aid is a methylmethacrylate-ethylacrylate copolymer.

18. The composition of claim 14 wherein the high molecular weight acryHc copolymer processing aid is a butyHnethacrylate-methacrylate copolymer.

19. The composition of claim 14 where the weight average molecular weight of the high molecular weight acrylic copolymer processing aid is above 400K daltons.

20. The compositoin of claim 15 where the weight average molecular weight of the high molecular weight acryHc copolymer processing aid is above 400K daltons.

21. A thermoplastic composition having reduced gate blush comprising: a. polycarbonate; b. an acrylonitrUe-butylacrylate-styrene resin; and c. a high molecular weight acryHc copolymer processing aid.