MXPA00009616A - Polycarbonate/rubber-modified graft copolymer resin blends having improved thermal stability - Google Patents

Abstract

A thermoplastic resin composition that contains a branched polycarbonate resin, a rubber modified graft copolymer that contains a discontinuous elastomeric phase dispersed in a continuous rigid thermoplastic phase, wherein at least a portion of the rigid thermoplastic phase is chemically grafted to the elastomeric phase, a sterically hindered phenol stabilizer compound, a thioester stabilizer compound and a phosphite stabilizer compound, exhibits improved stability.

Description

POLYCARBONATQ RESIN MIXTURES AND GRAINED, GRAINED COPQLIMERQ WITH HULE THAT HAVE ENHANCED THERMAL STABILITY FIELD OF THE INVENTION The present invention relates to thermoplastic resin compositions based on blends of a polycarbonate resin and a grafted copolymer modified with rubber, and exhibiting improved thermal stability.

BRIEF DESCRIPTION OF THE RELATED ART The use of various phenolic, sulfur-containing, phosphite stabilizers is known generically in the art, either individually or in combination, to stabilize thermoplastic resin compositions; see, for example, the patent of E.U.A. No. 4,525,514. Thermoplastic resin compositions exhibiting improved thermal stability are desired.

BRIEF DESCRIPTION OF THE INVENTION The thermoplastic resin composition of the present invention comprises: a) an aromatic polycarbonate resin, b) a grafted copolymer modified with rubber, comprising a discontinuous elastomer phase dispersed in a continuous rigid thermoplastic phase, wherein at least a portion of the rigid thermoplastic phase is chemically grafted to the elastomeric phase , c) a sterically hindered phenolic stabilizing compound according to the structural formula: wherein 1 and R2 are each independently C 1 -C 12 alkyl, and R 3 is C 1 -C 12 alkyl, C 1 -C 12 hydroxyalkyl or C 1 -C 4 alkoxycarboxy-C 1 -C 12 alkyl, d) a stabilizing compound of thioester according to the structural formula: wherein R4 is C1-C24 alkyl, or according to the structural formula: O II [R5- S-CH ^ r ^ - C-O-CH ^ -C wherein R5 is C1-C24 alkyl, and e) a phosphite stabilizing compound according to the structural formula: wherein Re is C1-C24 alkyl or monocyclic aryl, optionally substituted with up to three C1-C12 alkyl groups, or according to the structural formula: wherein R7, R8, R9, R10 and R11 are each independently dC? 2 alkyl. The composition of the present invention exhibits unexpectedly improved thermal stability.

DETAILED DESCRIPTION OF THE INVENTION In a first preferred embodiment, the thermoplastic resin composition of the present invention comprises from 15 to 85 parts by weight ("pbw"), more preferably from 50 to 80 pbw, even more preferably from 60 to 75 pbw, of the aromatic polycarbonate resin, from 15 to 85 pbw, more preferably from 20 to 50 pbw, even more preferably from 25 to 50 pbw, 40 pbw of the grafted copolymer modified with rubber, from 0.01 to 1.0 pbw, more preferably from 0.05 to 0.5 pbw, even more preferably from 0.1 to 0.4 pbw, of the sterically hindered phenolic stabilizing compound, and from 0.01 to 1.0 pbw, more preferably from 0.05 to 0.5 pbw, even more preferably 0.1 to 0.4 pbw, of the thioester stabilizing compound, and 0.01 to 1.0 pbw, more preferably 0.05 to 0.5 pbw, even more preferably 0.1 to 0.4 pbw of the phosphite stabilizing compound, each one based on 100 pbw of the combined amount of aromatic polycarbonate resin and rubber modified graft copolymer. In a second preferred embodiment, the thermoplastic resin composition of the present invention comprises an aromatic polycarbonate resin, a rubber modified graft copolymer, a sterically hindered phenolic stabilizer, a thioester stabilizer and a phosphite stabilizer as described above, and further comprises a phosphate flame retardant. In a more highly preferred embodiment, the composition comprises from 55 to 90 pbw, more preferably from 60 to 85 pbw, even more preferably from 68 to 82 pbw, of the aromatic polycarbonate resin, from 3 to 11 pbw, more preferably from 4 at 10 pbw, even more preferably from 4.5 to 9.5 pbw, of the rubber modified graft copolymer, from 2 to 20 pbw, more preferably from 5 to 15 pbw, even more preferably from 7 to 12 pbw, phosphate flame retardant, from 0.01 to 1.0 pbw, more preferably from 0.05 to 0.5 pbw, even more preferably more than 0.15 to 0.4 pbw, of the sterically hindered phenolic stabilizing compound, and from 0.01 to 1.0 pbw, more preferably from 0.05 to 0.5 pbw, even more preferably more than 0.15 to 0.4 pbw, of the thioester stabilizing compound, and 0.01 to 1.0 pbw, more preferably 0.05 to 0.5 pbw, even more preferably more than 0.15 to 0.4 pbw of the phosphite stabilizing compound, each based on 100 pbw of the combined amount of aromatic polycarbonate resin, rubber modified graft copolymer and phosphate flame retardant.

Aromatic Polycarbonate Resin Aromatic polycarbonate resins suitable for use as the aromatic polycarbonate resin component of the thermoplastic resin composition of the present invention are known compounds whose preparation and properties have been described; see, generally, the patents of E.U.A. Nos. 3,169,121, 4,487,896 and 5,411, 999, the respective descriptions of which are incorporated herein by reference. In a preferred embodiment, the aromatic polycarbonate resin component of the present invention is a reaction product of a dihydric phenol according to structural formula (I): HO-A-OH (I) wherein A is a divalent aromatic radical, with a carbonate precursor, and contains structural units according to formula (II): O - (O-A-O-C) - (II) where A is as defined above. As used herein, the term "divalent aromatic radical" includes those divalent radicals containing an individual aromatic ring such as phenylene, those divalent radicals containing a fused aromatic ring system such as, for example, naphthalene, those divalent radicals containing two or more aromatic rings joined by non-aromatic bonds, such as, for example, an alkylene, alkylidene or sulfonyl group, any of which may be substituted at one or more sites on the aromatic ring with, for example, a group halogen or C ^ Ce alkyl group. As used herein to modify an organic substituent group, the notation "(Cx-Cy)", wherein x and y are each integer, means that the organic substituent group contains x carbon atoms a and carbon atoms per group. In a preferred embodiment, A is a divalent aromatic radical according to formula (III): (III) ^ J ^ g ^^^ 3¡ »^^^^^^^^^^^^^ g¡ > ^ Suitable dihydric phenols include, for example, one or more of 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'-dihydroxyphenyl) propane, 2,6-dihydroxynaphthalene, hydroquinone and 2,4'-dihydroxyphenyl sulfone. In a highly preferred embodiment, the dihydric phenol is bisphenol A. The carbonate precursor is one or more of a carbonyl halide, a carbonate ester or a halogenoformate. Suitable carbonyl halides include, for example, carbonyl bromide and carbonyl chloride. Suitable carbonate esters include, for example, diphenyl carbonate, dichlorophenyl carbonate, dinaphthyl carbonate, phenyl tolyl carbonate, and ditolyl carbonate. Suitable halogenoformates include, for example, bishalogenoformates and dihydric phenols such as, for example, hydroquinone, or glycols such as, for example, ethylene glycol or neopentyl glycol. In a highly preferred embodiment, the carbonate precursor is carbonyl chloride. Suitable aromatic polycarbonate resins include linear aromatic polycarbonate resins and branched aromatic polycarbonate resins. Suitable linear aromatic polycarbonate resins include, for example, bisphenol A polycarbonate resin. Suitable branched polycarbonates are known and are obtained by reacting a polyfunctional aromatic compound with a dihydric phenol and a carbonate precursor to form a branched polymer; see, generally, the patents of E.U.A. Nos. 3,544,514; 3,635,895 and 4,001, 184, the respective descriptions of which are incorporated herein by reference. The polyfunctional compounds are generally aromatic and contain at least three functional groups which are carboxyl, carboxylic anhydrides, phenols, halogenoformates, or mixtures thereof, such as, for example, 1,1-tri (4-hydroxyphenyl) ethane, 1, 3,5-trihydroxy-benzene, trimellitic anhydride, trimellitic acid, trimellitic trichloride, 4-chloroformyl phthalic anhydride, pyromellitic acid, pyromellitic dianhydride, mellitic acid, mellitic anhydride, trimesic acid, benzophenonetracarboxylic acid or benzophenonetracarboxylic dianhydride. Preferred polyfunctional aromatic compounds are 1, 1, 1-tri (4-hydroxyphenyl) ethane, trimellitic anhydride or trimellitic acid or their halogenoformate derivatives. 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 from about 10,000 to more than 200,000 g / mol, as determined by gel permeation chromatography relative to polystyrene. Said resin typically exhibits an intrinsic viscosity of from about 0.3 to about 1.5 deciliters per gram in methylene chloride at 25 ° C.

The polycarbonate resins are obtained by known methods such as, for example, interfacial polymerization, transesterification, solution polymerization or polymerization of molten material. The copolyester-carbonate resins suitable for use as component (c) of the thermoplastic resin composition of the present invention are known compounds whose preparation and properties have been described; see, generally, the patents of E.U.A. Nos. 3,169,121, 4,430,484 and 4,487,896, the respective descriptions of which are incorporated herein by reference. The copolyester-carbonate resins comprise linear or randomly branched polymers containing recurring carbonate groups, carboxylate groups and aromatic carbocyclic groups in the polymer chain, in which at least some of the carbonate groups are directly attached to the carbon atoms of ring of aromatic carbocyclic groups. In a preferred embodiment, the copolyester-carbonate resin component of the present invention is derived from a carbonate precursor, at least one dihydric phenol and at least one dicarboxylic acid or dicarboxylic acid equivalent. In a preferred embodiment, the dicarboxylic acid is one according to formula (IV): O O II II HO-C-A'-C-OH (IV) wherein A 'is alkylene, alkylidene, cycloaliphatic or aromatic, and is preferably an unsubstituted phenylene radical or a substituted phenylene radical which is substituted at one or more sites on the aromatic ring, wherein each of said substituent groups is independently Ci-Cß alkyl, and the copolyester-carbonate resin comprises first structural units according to formula (II) above, and second structural units according to formula (V): OO II II - (OCAC) - (V ) where A 'is as defined above. Suitable dihydric phenols and carbonate precursors are those described 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, acid malonic dimethyl, 1,2-dodecanoic acid, c / s-1,4 acid, cyclohexanedicarboxylic acid, fraps-1,4-cyclohexanedicarboxylic acid, 4,4'-bisbenzoic acid and naphthalene-2,6-dicarboxylic acid. Suitable dicarboxylic acid equivalents include, for example, anhydride, ester or halide derivatives of the dicarboxylic acids described above such as, for example, phthalic anhydride, dimethyl terephthalate and succinyl chloride.

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: carbonate bonds present in the copolyester-carbonate resin is 0.25 to 0.9 ester bonds per carbonate bond. In a preferred embodiment, the copolyester-carbonate copolymer has a weight average molecular weight of from about 10,000 to about 200,000 g / mol. The copolyester-carbonate resins are obtained by known methods such as, for example, interfacial polymerization, transesterification, solution polymerization or polymerization of molten material.

Rubber Modified Thermoplastic Resin Rubber-modified thermoplastic resins such as the rubber modified thermoplastic resin of the present invention comprise a discontinuous elastomer phase dispersed in a continuous rigid thermoplastic phase, wherein at least a portion of the rigid thermoplastic phase is grafted chemically to the elastomeric phase, and are known compounds whose preparation and properties have been described. (a) Elastomeric phase The materials suitable for use as the elastomeric phase are those polymers having a glass transition temperature (Tg) less than or equal to 25 ° C., more preferably less than or equal to 0 ° C, and even more preferably less than or equal to -30 ° C. As referred to herein, the Tg of a polymer is the Tg value of the polymer, as measured by differential scanning calorimetry (heating rate of 20 ° C / minute, the value of Tg being determined at the inflection point). In a preferred embodiment, the elastomeric phase comprises a polymer having structural units derived from one or more monoethylenically unsaturated monomers selected from conjugated diene monomers, non-conjugated diene monomers or C 1 -C 12 alkyl (meth) acrylate monomers. Suitable conjugated diene monomers include, for example, 1,3-butadiene, isoprene, 1,3-heptadiene, methyl-1,3-pentadiene, 2,3-dimethylbutadiene, 2-ethyl-1,3-pentadiene, 1 , 3-hexadiene, 2,4-hexadiene, dichlorobutadiene, bromobutadiene and dibromobutadiene, as well as mixtures of conjugated diene monomers. In a preferred embodiment, the conjugated diene monomer is 1,3-butadiene. Suitable non-conjugated diene monomers include, for example, ethylidene norbornene, dicyclopentadiene, hexadiene or phenyl norbornene.

As used herein, the term "C 1 -C 12 alkyl" means a linear or branched alkyl substituent group having from 1 to 12 carbon atoms. carbon per group, and includes, for example, methyl, ethyl, n-butyl, sec-butyl, t-butyl, n-propyl, isopropyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl and dodecyl, and The term "(meth) acrylate monomers" refers collectively to acrylate monomers and methacrylate monomers. Suitable C 1 -C 12 alkyl (meth) acrylate monomers include C 1 -C 2 alkyl acrylate monomers, for example, ethyl acrylate, butyl acrylate, isopentyl acrylate, n-hexyl acrylate, 2-ethyl acrylate. hexyl, and its C1-C12 alkyl methacrylate analogs such as, for example, methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, butyl methacrylate, hexyl methacrylate and decyl methacrylate. The elastomeric phase may optionally include up to about 40 weight percent of one or more monomers selected from C-C8 olefin monomers, vinyl aromatic monomers and monoethylenically unsaturated nitrile monomers. As used herein, the term "olefin monomers of C2-Cβ "means a compound having from 2 to 8 carbon atoms per molecule and having a single site of ethylenic unsaturation per molecule.The suitable C2-C8 olefin monomers include, for example, ethylene, propene, 1 - butene, 1-pentene and heptene Suitable vinyl aromatic monomers include, for example, styrene and substituted styrenes having one or more alkyl, alkoxy, hydroxyl or halogen substituent groups attached to the aromatic ring, including, for example, methyl styrene, p-methyl styrene, vinyl toluene, vinyl xylene, trimethyl styrene, butyl styrene, chlorostyrene, dichlorostiene, bromostyrene, p-hydroxystyrene, methoxystyrene and vinyl substituted fused aromatic ring structures such as, for example, vinyl naphthalene, vinyl anthracene, as well as mixtures of vinyl aromatic monomers. As used herein, the term "monoethylenically unsaturated nitrile monomer" means an acyclic compound that includes an individual nitrile group and an individual site of ethylenic unsaturation per molecule, and includes, for example, acrylonitrile, methacrylonitrile, and -chloro acrylonitrile. . The elastomeric phase may optionally include a minor amount, for example, up to 5% by weight, of structural units derived from a polyethylenically unsaturated "entanglement" monomer, for example, butylene diacrylate, divinyl benzene, butenediol dimethacrylate or tri (methyl) ) trimethylolpropane acrylate. As used herein, the term "pohetylenically unsaturated" means having two or more sites of ethylenic unsaturation per molecule. The elastomeric phase can include, particularly in those embodiments wherein the elastomeric phase has structural units derived from alkyl (meth) acrylate monomers, a minor amount, for example, up to 5% by weight of structural units derived from a monomer of "polyethylenically unsaturated" graft binding. Suitable graft-binding monomers include those monomers having a first site of ethylenic unsaturation with a reactivity similar to that of the monoethylenically unsaturated monomers from which the substrate or respective supersubstrate is derived, and a second ethylenic supersaturation site with a relative reactivity that is substantially different from that of the monoethylenically unsaturated monomers from which the elastomeric phase is derived, so that the first site reacts during the synthesis of the elastomeric phase, and the second site is available for subsequent reaction under different reaction conditions, for example, during the synthesis of the rigid thermoplastic phase. Suitable graft-binding monomers include, for example, allyl methacrylate, diallyl maleate and triallyl cyanurate. In a preferred embodiment, the elastomeric phase comprises from 60 to 100% by weight of structural units derived from one or more conjugated diene monomers and from 0 to 40% by weight of structural units derived from one or more monomers selected from aromatic monomers of vinyl and monoethylenically unsaturated nitrile monomers such as, for example, a styrene-butadiene copolymer, an acrylonitrile-butadiene copolymer or a styrene-butadiene-acrylonitrile copolymer. In a preferred alternative embodiment, the elastomeric phase comprises structural units derived from one or more C C 2 alkyl acrylate monomers. In a more highly preferred embodiment, the elastic polymeric substrate comprises from 40 to 95% by weight of structural units derived from one or more C12 alkyl acrylate monomers, more preferably from one or more monomers selected from ethyl acrylate, acnlate of butyl and n-hexyl acrylate.

In a preferred embodiment, the elastomeric phase is obtained by aqueous emulsion polymerization in the presence of a free radical initiator, for example, an azonitrile initiator, an organic peroxide initiator, a persulfate initiator or a redox initiator system and , optionally, in the presence of a chain transfer agent, for example, an alkyl mercaptan and coagulated to form particles of elastomeric phase material. In a preferred embodiment, the emulsion polymerized particles of the elastomeric phase material have a weight average particle size of 50 to 800 nm, more preferably 100 to 500 nm, as measured by light transmission. The size of the emulsion polymerized elastomeric particles can optionally be increased by mechanical or chemical agglomeration of the emulsion polymerized particles, according to known techniques. (b) Rigid thermoplastic phase The rigid thermoplastic ream phase comprises one or more thermoplastic polymers, and exhibits a Tg greater than 25 ° C, preferably greater than or equal to 90 ° C, and even more preferably greater than or equal to 100. ° C. In a preferred embodiment, the rigid thermoplastic phase comprises a polymer or a mixture of two or more polymers, each having structural units derived from one or more monomers selected from the group consisting of C1-C12 alkyl (meth) acrylate monomers. , vinyl aromatic monomers and monoethylenically unsaturated nitrile monomers. The C 1 -C 12 alkyl (meth) acrylate monomers, vinyl aromatic monomers and suitable monoethylenically unsaturated nitrile monomers are those described above in the description of the elastomeric phase. In a highly preferred embodiment, the rigid thermoplastic phase comprises one or more vinyl aromatic polymers. Suitable vinyl aromatic polymers comprise at least 50% by weight of structural units derived from one or more vinyl aromatic monomers. In a preferred embodiment, the rigid thermoplastic resin phase comprises an aromatic vinyl polymer having first structural units derived from one or more vinyl aromatic monomers, and having second structural units derived from one or more monoethylenically unsaturated nitrile monomers. The rigid thermoplastic phase is obtained according to known processes, for example, bulk polymerization, emulsion polymerization, suspension polymerization, or combinations thereof, wherein at least a portion of the rigid thermoplastic phase is chemically bonded, is say, "grafted" to the elastomeric phase by reaction with unsaturated sites present in the elastomeric phase. The unsaturated sites in the elastomeric phase are provided, for example, by residual unsaturated sites in structural units derived from a conjugated diene or by residual unsaturated sites in structural units derived from a graft-binding monomer.

In a preferred embodiment, at least a portion of the rigid thermoplastic phase is obtained by an aqueous emulsion reaction or polymerization reaction in aqueous suspension, in the presence of an elastomeric phase and a polymerization initiator system, for example, a system of thermal initiator or redox. In a preferred alternative embodiment, at least a portion of the thermoplastic phase is obtained by a bulk polymerization process, wherein particles of the material from which the elastomeric phase will be formed, are dissolved in a solvent, and added to a mixture. of the monomers from which the rigid thermoplastic phase will be formed, and the monomers of the mixture are then polymerized to form the rubber modified thermoplastic resin. The degree of grafting that takes place between the rigid thermoplastic phase and the elastomeric phase varies with the relative amount and composition of the elastomeric phase. In a preferred embodiment, from 10 to 90% by weight, preferably from 25 to 60% by weight, from the rigid thermoplastic phase is chemically inserted into the elastomeric phase, and from 10 to 90% by weight, preferably from 40 to 75% by weight of the rigid thermoplastic phase, remains "free" that is, not grafted. The rigid thermoplastic phase of the rubber modified thermoplastic resin can be formed: (i) only by polymerization carried out in the presence of the elastomeric phase, or (ii) by the addition of one or more rigid thermoplastic polymers separately polymerized to a polymer rigid thermoplastic that has been polymerized in the presence of the elastomeric phase. In a preferred embodiment, the rubber modified thermoplastic resin comprises an elastomeric phase comprising a polymer having structural units derived from one or more conjugated diene monomers and, optionally, further comprising structural units derived from one or more monomers selected from aromatic monomers of vinyl and monoethylenically unsaturated nitrile monomers, and the rigid thermoplastic phase comprises a polymer having structural units derived from one or more monomers selected from vinyl aromatic monomers and monoethylenically unsaturated nitrile monomers. Each of the polymers of the elastomeric phase and of the rigid thermoplastic resin phase of the rubber-modified thermoplastic resin may optionally include, so long as the Tg limitation of the respective phase is satisfied, up to 10% by weight of the third units. structural derivatives of one or more other copolymerizable monomers such as, for example, monoethylenically unsaturated carboxylic acids such as, for example, acrylic acid, methacrylic acid, itaconic acid, C1-C12 hydroxyalkyl (meth) acrylate monomers such as, for example, hydroxyethyl methacrylate; C4-C12 cycloalkyl (meth) acrylate monomers such as, for example, cyclohexyl methacrylate; (meth) acrylamide monomers such as, for example, acrylamide and methacrylamide; maleimide monomers such as, for example, N-alkyl maleimides, N-aryl maleimides, maleic anhydride, esters of vinyl such as, for example, vinyl acetate and vinyl propionate. As used herein, the term "C4-C12 cycloalkyl" means a cyclic alkyl substituent group having from 4 to 12 carbon atoms per group, the term "(meth) acrylamide" refers collectively to acrylamides and methacrylamides.

Sterically hindered phenolic stabilizer The sterically hindered phenolic stabilizing compounds suitable for use as the sterically hindered phenolic stabilizing compound of the present invention are known compounds, and are obtained by known methods and are commercially available. In a preferred embodiment, the phenolic stabilizing component of the composition is a monophenolic stabilizer according to structural formula (VI): wherein: R1 and R are each independently C? -C12 alkyl, and R3 is C1-C12 alkyl, C1-C12 hydroxyalkyl or C? -C24 alkoxycarbonyl C1-C12 alkyl. ? ? *. ^? -.._ In a preferred embodiment, Ri and R2 are each C2-C8 alkyl. In a more highly preferred embodiment, R1 and R2 are each t-butyl. In a preferred embodiment, R3 is Ci-Cβ hydroxyalkyl or C1-C16 alkoxycarbonyl CrC12 alkyl. In a more highly preferred embodiment, R3 is octadecyloxycarbonylethyl. Suitable compounds according to formula (VI) include, for example, 2,6-di-t-butyl-p-cresol, 4- (hydroxymethyl) -2,6-di-t-butylphenol and 2,6- di-t-butyl-4-sec-butylphenol. In a highly preferred embodiment, the phenolic stabilizing component of the composition of the present invention comprises octadecyl 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate.

Thioester Stabilizing Compound The thioester stabilizing compounds suitable for use as the thioester stabilizing compound of the present invention are known compounds, are obtained by known methods and are commercially available. In a preferred embodiment, the thioester stabilizing component of the composition of the present invention is a compound according to structural formula (VII) or (VIII): wherein R 4 is C 1 -C 24 alkyl, or wherein R5 is C1-C24 alkyl. In a preferred embodiment, 4 is C 8 -C 6 alkyl. Suitable compounds according to formula (VII) include, for example, dilauryl thiodipropionate, dimyristyl thiodipropionate and distearyl thiodipropionate. In a preferred embodiment, R5 is C8-Ci6 alkyl. Suitable compounds according to formula (VIII) include, for example, pentaerythritol tetrakis (3- (dodecylthio) propionate.) In a highly preferred embodiment, the thioester stabilizing component of the composition of the present invention is tetrakis (3- Pentaerythritol (dodecylthio) propionate.

Phosphite stabilizer compound Phosphite stabilizer compounds suitable for use as the phosphite stabilizer compound of the present invention are known compounds, are obtained by known methods and are commercially available.

In a preferred embodiment, the phosphite stabilizing component of the composition of the present invention is a compound according to structural formula (IX): wherein Re is C 1 -C 24 alkyl or monocyclic aryl, optionally substituted with up to three C 1 -C 12 alkyl groups; or according to the structural formula (X): wherein R7, R8, R9, R and Rn are each independently selected from C1-C12 alkyl. In a preferred embodiment, Re is C8-C24 alkyl or phenyl substituted with two independently selected C6-C6 alkyl groups.

In a more preferred embodiment, R6 is 2,4-di-t-butylphenyl. Suitable compounds according to formula (IX) include, for example, distearylpentaerythritol diphosphite and bis (2,4-di-tert-butyl) pentaerythritol diphosphite.

In a preferred embodiment, R7, R8, Rg, Rio and Rn are each independently C? -C6 alkyl. In a most preferred embodiment, R7 is n-butyl, R8 is ethyl and Rg, R10 and Rn are each t-butyl. In a highly preferred embodiment, the phosphite stabilizer comprises bis (2,4-di-tert-butyl) pentaerythritol.

Orqanophosphoric Flame Retardant Organophosphorous compounds suitable as the organophosphorus flame retardant of the present invention are known compounds which include monophosphate esters such as, for example, triphenyl phosphate, tricresyl phosphate, tritolyl phosphate, diphenyltrisyl phosphate, phosphate phenylbisdodecyl, ethyldiphenyl phosphate, as well as diphosphate esters and oligomeric phosphates such as, for example, resorcinol diphosphate, diphenyl acid phosphate, 2-ethylhexyl acid phosphate. Suitable oligomeric phosphate compounds are described in the U.S.A. co-assigned number 5,672,645, to Johannes C. Gossens et al., for "Polymeric Blend Having Aromatic Polycarbonate, Copolymer Containing Styrene and / or Graft Copolymer and a Flame Retardant, Articles Formed From The Same", the description of which is incorporated in the present as a reference. In a preferred embodiment, the organophosphorus flame retardant of the present invention comprises one or more compounds according to the structural formula (XI): OO Rl 2 - (O) - P-CJ- [XCP- (0) d-] n-Ri 5 (O) b (0) C R 13 14 (where R 12, R 13, R 14 and R 15 are each independently aryl, which may be optionally substituted with halogen or alkyl, X is arylene, optionally substituted with halogen or alkyl, a, b, c and d are each independently 0 or 1, and n is an integer from 0 to 5, most preferably from 1 to 5. As used herein, "aryl" means a monovalent radical containing one or more aromatic rings per radical, which, in the case where the radical contains two or more rings, may be fused rings and which may be optionally substituted in the one or more aromatic rings with one or more alkyl groups, each preferably Ci-Ce alkyl. As used herein, arylene means a divalent radical containing one or more aromatic rings per radical, which may be optionally substituted in the one or more aromatic rings with one or more groups alq uilo, each preferably C-C alkyl and which, in the case where the divalent radical contains two or more rings, the rings can be fused or can be joined by non-aromatic bonds, such as, for example, an alkylene, alkylidene , any of which can be substituted at one or more sites in the aromatic ring with a halogen group or C1-C6 alkyl group.

In a highly preferred embodiment, R 12, R 13, R 14 and R 15 are each phenyl, a, b, c and d are each 1 and X is phenylene, most preferably 1,3-phenylene. In an alternative and highly preferred embodiment, R12, R13, R14 and R15 are each phenyl, a, b, c and d are each 1 and X is a divalent radical according to structural formula (XII): (XII) In a preferred embodiment, the organophosphorus flame retardant comprises a mixture of organophosphorus oligomers, each according to formula (VI), wherein n is, independently for each oligomer, an integer from 1 to 5, and in wherein the mixture of oligomers has an average n of more than 1 to less than 5, most preferably more than 1 to less than 3, still more preferably more than 1 to less than 2, even more preferably 1.2 to 1. 7 Fluoropolymer Additive In a preferred embodiment, the composition of the present invention includes a fluoropolymer, in an amount typically from 0.01 to 0.5 pbw of fluoropolymer per 100 pbw of the thermoplastic resin composition, which is effective to provide anti-drip properties to the composition of resin.

Suitable fluoropolymers and methods for making such fluoropolymers are known, see, for example, U.S.A. Nos. 3,671, 487, 3,723,373 and 3,383,092. Suitable fluoropolymers include homopolymers and copolymers comprising structural units derived from one or more fluorinated α-olefin monomers. The term "fluorinated α-olefin monomer" means an α-olefin monomer that includes at least one fluorine atom substituent. Suitable fluorinated α-olefin monomers include, for example, fluoroethylenes such as, for example, CF 2 = CF 2, CHF = CF 2, CH 2 = CF, CH 2 = CHF, CCIF = CF 2, CCI 2 = CF 2, CCIF = CCIF, CHF = CCI2, CH2 = CCIF and CCI2 = CCIF and fluoropropylenes, such as, for example, CFsCF = CF2, CF3CF = CHF, CF3CH = CF2, CF3CH = CH2, CF3CF = CHF, CHF2CH = CHF and CF3CH = CH2. In a preferred embodiment, the fluorinated α-olefin monomer is one or more of tetrafluoroethylene (CF2 = CF), chlorotrichloroethylene (CCIF = CF), vinyliene fluoride (CH2 = CF) and hexafluoropropylene (CF2 = CFCF3). Suitable fluorinated α-olefin homopolymers include, for example, poly (tetrafluoroethylene) and poly (hexafluoroethylene). Suitable fluorinated α-olefin copolymers include copolymers comprising structural units derived from two or more fluorinated α-olefin copolymers such as, for example, polytetrafluoroethylene-hexafluoroethylene), and copolymers comprising structural units derived from one or more fluorinated monomers and from one or more non-fluorinated monoethylenically unsaturated monomers which are copolymerizable with the fluorinated monomers such as, for example, copolymers of poly (tetrafluoroethylene-ethylene-propylene). Suitable non-fluorinated monoethylenically unsaturated monomers include, for example, α-olefin monomers such as, for example, ethylene, propylenebutene, acrylate monomers such as, for example, methyl methacrylate, butyl acrylate, vinyl ethers such as, for example, example, cyclohexyl vinyl ether, ethyl vinyl ether, n-butyl vinyl ether, vinyl esters such as, for example, vinyl acetate and vinyl versatate. In a preferred embodiment, the fluoropolymer particles vary in size from 50 to 500 nm, as measured by electron microscopy.

PTFE thermoplastic as described, for example, in the US patent. No. 4,579,906. In a preferred embodiment, the fluoropolymer additive comprises from 30 to 70% by weight, most preferably 40 to 60% by weight of the fluoropolymer and from 30 to 70% by weight, more preferably 40 to 60% by weight of the second polymer. In a preferred embodiment, a fluoropolymer additive is made by emulsion polymerization of one or more monoethylenically unsaturated monomers in the presence of the aqueous fluoropolymer dispersion of the present invention to form a second polymer in the presence of the fluoropolymer. Suitable monoethylenically unsaturated monomers are described above. The emulsion is then precipitated, for example, by the addition of sulfuric acid. The precipitate is dehydrated, for example, by centrifugation, and then dried to form a fluoropolymer additive comprising fluoropolymer and a second associated polymer. The dry emulsion polymerized fluoropolymer additive is in the form of a free flowing powder. In a preferred embodiment, the monoethylenically unsaturated monomers which are the emulsion polymerized to form the second polymer comprise one or more monomers selected from vinyl aromatic monomers, monoethylenically unsaturated nitrile monomer and monomers from C 1 -C 12 alkyl (meth) acrylate. Vinyl aromatic monomers, monoethylenically unsaturated nitrile monomer and C 1 -C 12 alkyl (meth) acrylate monomers are described above. In a highly preferred embodiment, the second polymer comprises structural units derived from styrene and acrylonitrile. Most preferably, the second polymer comprises from 60 to 90% by weight of structural units derived from styrene and from 10 to 40% by weight of structural units derived from acrylonitrile. The emulsion polymerization reaction mixture may optionally include emulsified or dispersed particles of a third polymer, such as, for example, an emulsified butadiene rubber latex. The emulsion polymerization reaction is initiated using a conventional free radical initiator such as, for example, an organic peroxide compound, such as, for example, benzoyl peroxide, a persulfate compound, such as, for example, persulfate potassium, an azonitrile compound such as, for example, 2,2'-azobis-2,3,3-trimethylbutyronitrile, or a reduction oxide initiator system, such as, for example, a combination of eumenal hydroperoxide, ferrous sulfate , tetrasodium thyrophosphate and a reducing sugar or sodium formaldehyde sulfoxylate. A chain transfer agent, such as, for example, a (C9-C13) alkylmercaptan compound such as nonylmercaptan, t-dodecyl mercaptan, can optionally be added to the reaction vessel during the polymerization reaction to reduce molecular weight of the second polymer. In a preferred embodiment, no chain transfer agent is used. In a preferred embodiment, the stabilized fluoropolymer dispersion is charged to a container and heated with stirring. The initiator system and the one or more monoethylenically unsaturated monomers are then charged to a reaction vessel and heated to polymerize the monomers in the presence of the fluoropolymer particles of the dispersion to thereby form the second polymer. Suitable fluoropolymer additives and emulsion polymerization methods are described in EP 0 739 914 A1. In a preferred embodiment, the second polymer exhibits a weight average molecular weight of from about 10,000 to about 200,000 g / mol.

Other additives The thermoplastic resin composition of the present invention may also optionally contain various conventional additives, such as UV absorbers and light stabilizers, fillers and reinforcing agents, lubricants, plasticizers, optical brighteners, pigments, dyes, dyes, agents flameproof; antistatic agents; blowing agents and flame retardant additives, as well as other antioxidants, stabilizers and flame retardant compounds in addition to those described above.

In a preferred embodiment, the composition contains a modified surface Ti0 which is coated with one or more layers of one or more organopolysiloxane polymers selected from the linear organosiloxane polymers, branched organosiloxane polymers and mixtures thereof. In a highly preferred embodiment, the coating contains an organosiloxapo polymer having Si-H bonds, such as, for example, a dimethylpolysiloxane in which all or part of the dimethylpolysiloxane units are replaced with methyl acid siloxane units. Suitable surface modified TIO2 and suitable organopolysiloxane polymers are described, for example, in the US patent. No. 5,389,714, the disclosure of which is incorporated herein by reference. The thermoplastic resin composition of the present invention is made by combining and mixing the components of the composition of the present invention under conditions suitable for the formation of a mixture of the components, such as, for example, melt blending using, for example, a two-roll mill, a Banbury mixer or an individual worm or worm extruder, and, optionally, then reducing the composition thus formed to a particulate form, for example, by pelletizing or spraying the composition. The thermoplastic resin composition of the present invention can be molded to create shaped articles useful by a variety of means such as injection molding, extruder, rotary molding, molding. by blowing and thermoforming to form articles such as, for example, cases for computers and home-made machines, and home appliances.

Examples 1-4 and Comparative Examples C1-C5 The respective thermoplastic resin compositions of Comparative Examples C1-C5 and Examples 1-4 of the present invention were each made by combining the components described below in the relative amounts (each expressed in parts by weight) described in tables l-ll. The components used in the thermoplastic resin compositions were as follows: PC-1: Linear polycarbonate resin derived from bisphenol A, phosgene and having a melt flow index of about 10 grams per minute at 300 ° C, using a weight of 1.2 kilograms; PC-2: Linear polycarbonate resin derived from bisphenol A, phosgene and having a melt flow rate of about 7 grams per minute at 300 ° C, using a weight of 1.2 kilograms; ABS: Emulsion polymerized acrylonitrile-butadiene-styrene graft copolymer comprising 50% by weight of a discontinuous elastomeric phase (polybutadiene) and 50% by weight of a rigid thermoplastic phase (copolymer of 75% by weight of styrene and 25% by weight) by weight of acrylonitrile); SAN-1: 75% styrene and 25% acrylonitrile copolymer having a weight average molecular weight of about 95,000 g / mol; SAN-2: Copolymer of 75% by weight of styrene and 25% by weight of acrylonitrile having a weight average molecular weight of approximately 62,000 g / mol. PHOS-1: Bis (2,4-di-tert-butyl) pentaerythritol diphosphite (Ultranox 626, GE Specialty Chemicals, Inc.); PHOS-2: 2,4-Di-ter- (butylphenyl) phosphite (Irgafos 168, Ciba-Geigy) PHENYL: octadecyl 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate (Irganox 1076, Ciba-Geigy); THIO: Tetrakis (3- (dodecylthio) propionate) of pentaerythritol (Seenox 412S, Argus Chemical Company); TSAN: Additive made by copolymerizing styrene and acrylonitrile in the presence of an aqueous dispersion of PTFE (50% by weight of PTFE, 50% by weight of a styrene-acrylonitrile copolymer containing 75% by weight of styrene and 25% by weight of acrylonitrile ); COLOR: Mixture of dyes and RDP: Resorcinol diphosphate (Fyroflex ™ RDP, Akzo Chemicals). Each of the compositions of examples 1 and 2 and comparative examples C1-C4 also contained 0.9 pbw of dyes, including Ti02 coated, and 0.5 pbw of a lubricant additive, and each of the compositions of example 3 and 4 and comparative example C5 also contained 0.15 pbw of a lubricant additive. In a series of runs, the components were combined in a Henschel mixer at room temperature for approximately one minute to form each of the respective compositions of Examples 1-3 and Comparative Examples C1-C5. The compositions were then extracted into strands, chopped into pellets. The compositions of Examples 1 and 2 and Comparative Examples C1-C4 were compression molded to form specimens (each approximately 1/16 of 25.4 mm thick) for the color test. The specimens of each of the compositions of Examples 1-2 and Comparative Examples C1-C4 were aged by heat at 210 ° C. The color change of the specimens with heat aging was monitored accordingly using a MacBeth 20/20 spectrophotometer. The readings of the spectrophotometer were used as a basis to calculate the CIELAB? E values for each of the specimens in each of the different residence times of heat aging. The results are described in table 1 as values? E at various residence times of heat aging for each of the compositions of examples 1 and 2 and comparative examples C1-C4.

TABLE I C1 C2 C3 C4 1 2 PC 70.5 70.5 70.5 70.5 70.5 70.5 ABS 9 9 9 9 9 9 SAN 8.3 8.3 8.3 8.3 8.3 8.3 RDP 11.5 11.5 11.5 11.5 11.5 11.5 TSAN 0.4 0.4 0.4 0.4 0.4 0.4 PHOS1 0.3 0.3 - - 0.3 0.15 POS2 - - - 0.3 - - PHENYL 0.3 - 0.3 0.3 0.3 0.15 THIO - 0.3 0.3 0.3 0.3 0.15 ? E at tt = 0 0 0 0 0 0 0 t = 2 hr 1.28 1.33 3.76 3.21 1.63 1 61 t = 3 hr 2.35 2 86 4.06 13.72 1.56 5.41 t = 6 hr 31.13 26.47 13.83 23.80 5.68 32.28 t = 12 hr 34.41 36.09 33.18 34.57 31.93 34.62 t = 24 hr 40.82 40.47 40.47 43.11 35.92 42.57 The compositions of Examples 1 and 2 exhibited improved stability, as evidenced by the less pronounced increase in the? E values with heat aging, as compared to the compositions of Comparative Examples C1-C4. The physical properties of the compositions of Examples 3 and 4 and Comparative Example C5 were sent as follows. The melt flow index ("MFI") was measured at 260 ° C using a weight of 5 kilograms. The resistance to Dart impact was measured according to ASTM D3763 (using disks with a diameter of 10 cm by 0.32 cm at a speed of 6.7 meters per second). Notch impact strength was measured, using a sample size of 6.35 cm by 1.27 cm by 0.317 cm, in accordance with ASTM D256. The tensile strength and elongation were measured in accordance with ASTM D638. The heat distortion temperature was measured at 18.56 kilograms per square centimeter on untempered 0.317 cm thick test specimens in accordance with ASTM D648. The results of the test are described below for comparative example C5 and example 3 in table II as follows: the heat distortion temperature, expressed in degrees centigrade ("HDT, ° C") MFI, expressed in grams per minute ("g / min"), notch impact resistance at room temperature and -40 ° C, expressed in kilograms-meter per centimeter ("kg-m / cm"), dart impact at -30 ° C and -40 ° C, expressed in kilograms-meter ("kg-m"), noting the percentage of specimens that exhibited a ductile fracture modulus ("ductile%"), tensile strength at elongation and rupture, expressed in kilolibres per inch square ("kpsi"), the elongation at break, expressed as a percentage of the original sample length ("%") and the melt viscosity at 288 ° C and at a shear rate of 100 s "1, expressed in Poise.

TABLE II C5 3 4 PC-1 - 69 - PC-2 69 - 69 ABS 15 18.2 15 SAN-2 16 12.8 16 POLIBUTENE 2 - 2 Black smoke - 0.5 - PHOS1 - 0.15 0.25 PHENYL - 0.25 0.25 THIO - 0.25 0.25 Properties Fusion viscosity (Poise) 3183 - 2982 MFI at 260 ° C (g / min) ~ 11.8 - Impact of notch, TA (kg-m / cm) 0.737 0.689 0.751 Notch impact, -40 ° C (kg- 0.445 0.592 0.549 m / cm) Dart impact, -30 ° C (m / kg) (0.6719 28.88 30.43 31.11 % ductile 70 100 100 Impact of dart, -40 ° C (m / kg) 30.00 30.90 33.68 % ductile 30 90 60 Resistance to tension at relaxation 8.25 7.62 8.40 (kpsi) Resistance to breaking stress 9.00 8.44 9.34 (kpsi) Elongation at break (%) 203 200 212 HDT (° C) 108 109 107 The composition of Examples 3 and 4 exhibited improved low temperature ductility, compared to the composition of Comparative Example 5.

Claims (15)

NOVELTY OF THE INVENTION CLAIMS

1. - A thermoplastic resin composition comprising: a) an aromatic polycarbonate resin, b) a rubber modified graft copolymer, comprising a discontinuous elastomer phase dispersed in a continuous rigid thermoplastic phase, wherein at least a portion of the phase rigid thermoplastic is chemically grafted to the elastomeric phase, c) a sterically hindered phenolic stabilizing compound according to the structural formula: wherein Ri and R2 are each independently C? -C12 alkyl, and 3 is C1-C12 alkyl, C1-C12 hydroxyalkyl or CrC24 alkoxycarbonyl-C1-C12 alkyl, d) a thioester stabilizing compound in accordance to the structural formula: wherein R 4 is C 1 -C 24 alkyl, or according to the structural formula:

O II [R5- S-CH2CH2- C-O-CH ^ -C wherein R 5 is C 24 alkyl, and e) a phosphite stabilizing compound according to the structural formula: wherein R 6 is C 24 alkyl or monocyclic aryl, optionally substituted with up to three C 1 -C 12 alkyl groups, or according to the structural formula: wherein R7, R8, R9, R10 and Rn are each independently C12 alkyl. 2. The composition according to claim 1, further characterized in that the composition comprises from 15 to 85 parts by weight of polycarbonate resin, from 15 to 85 parts by weight of the grafted copolymer modified with rubber, from 0.01 to 1.0 parts in weight of the sterically hindered phenolic stabilizing compound, 0.01 to 1.0 parts by weight of the thioester stabilizing compound and 0.01 to 1.0 parts by weight of the compound phosphite stabilizer, based on the combined amount of the aromatic polycarbonate resin and the rubber modified graft copolymer.

3. The composition according to claim 1, further characterized in that the composition further comprises a flame retardant amount of a phosphate flame retardant.

4. The composition according to claim 3, further characterized in that the composition comprises from 55 to 90 parts by weight of polycarbonate resin, from 3 to 11 parts by weight of the rubber modified graft copolymer, from 2 to 20 parts by weight. weight of the phosphate flame retardant, from 0.05 to 0.5 parts by weight of the sterically hindered phenolic stabilizing compound, from 0.01 to 1.0 parts by weight of the thioester stabilizing compound and from 0.01 to 1.0 parts by weight of the phosphite stabilizing compound, based on in the combined amount of the aromatic polycarbonate resin and the rubber modified graft copolymer.

5. The composition according to claim 3, further comprising a drip reducing amount of a fluoropolymer additive.

6. The composition according to claim 1, further characterized in that the aromatic polycarbonate resin comprises a ream of linear aromatic polycarbonate derived from bisphenol A and phosgene, and has a weight average molecular weight of the polycarbonate resin of about 10,000 at approximately 200,000 grams per mole.

7. - The composition according to claim 1, further characterized in that the rubber modified thermoplastic resin comprises an elastomeric phase comprising structural units derived from one or more conjugated diene monomers and a rigid thermoplastic phase comprising structural units derived from one or more monomers selected from vinyl aromatic monomers and monoethylenically unsaturated nitrile monomers.

8. The composition according to claim 3, further characterized in that the flame retardant organophosphorus of the present invention comprises one or more compounds according to the structural formula (XI): OO Rl2- (O) - P ??? O- fX-OP ?? - (0) d-] n-Ri5 (O) b (O) c R13 R14 (XI) wherein R 2, R 13, R 14 and R 15 are each independently aryl, which can be optionally substituted with halogen or alkyl, X is arylene, optionally substituted with halogen or alkyl, a, b, c and d are each independently 0 or 1 and n is an integer from 0 to 5. 9.- The composition of conformity with claim 8, further characterized in that the organophosphorus flame retardant comprises a mixture of organophosphorus compounds according to formula (XI), wherein, independently for each organophosphorus compound of the mixture, R 12, R 3, R and R 15 are each phenyl, a, b, c and d are each 1, X is 1,3-phenylene and n is an integer from 1 to 5, and wherein the mixture of oligomers has an average of more than 1 to less than 3. 10. The composition according to claim 5, further characterized in that the fluoropolymer additive comprises polytetrafluoroethylene. 11. The composition according to claim 1, further characterized in that the phenolic stabilizer comprises octadecyl 3- (3,5-di-tert-butyl-4-hydroxy-phenyl) propionate. 12. The composition according to claim 1, further characterized in that the thioester stabilizing component comprises pentaeptritol tetrakis (3- (dodecylthio) propionate.) 13. The composition according to claim 1, further characterized in that the stabilizer Contains phosphorus comprises bis (2,4-di-tert-butyl) pentaerythritol diphosphite 14.- A shaped article made by molding the composition according to claim 1. 15.- A thermoplastic resin composition, which is obtained by mixing: a) an aromatic polycarbonate resin, b) a rubber modified graft copolymer, comprising a discontinuous elastomer phase dispersed in a continuous rigid thermoplastic phase, wherein at least a portion of the rigid thermoplastic phase is chemically grafted to the elastomeric phase , c) a phenolic stabilizing compound sterically hindered according to the structural formula: wherein Ri and R2 are each independently C1-C12 alkyl, and R3 is C? -C12 alkyl, C1-C12 hydroxyalkyl or C? -C24 alkoxycarbon C1-C12 alkyl, d) a stabilizing compound of thioester according to the structural formula: wherein R 4 is C 1 -C 24 alkyl, or according to the structural formula: II [R5- S-CH ^ I-k- C-0-CH2C wherein 5 is C 24 alkyl, and e) a phosphite stabilizing compound according to the structural formula: wherein Re is C 24 alkyl or monocyclic aryl, optionally substituted with up to three C 1 -C 12 alkyl groups, or according to the structural formula: wherein R7, R8, Rg, R10 and R11 are each independently C1-C12 alkyl.