MXPA01004022A - Polycarbonate resin blends containing titanium dioxide - Google Patents

Abstract

Thermoplastic resin compositions containing an aromatic polycarbonate resin and a surface modified titanium dioxide having a first coating and no further coatings are disclosed. The compositions may include a rubber modified graft copolymer comprising a discontinuous rubber phase dispersed in a continuous rigid thermoplastic phase, wherein at least a portion of the rigid thermoplastic phase is chemically grafted to the rubber phase;a rigid copolymer;a fluoropolymer;and/or a flame retarding amount of an organophosphorus flame retardant. Preferred titanium dioxide include first coating materials of polyols or polysiloxanes. The thermoplastic resin compositions exhibit improved resistance to streaking compared to such thermoplastic resin compositions which incorporate titanium dioxide having a first coating and at least one additional coating.

Description

POLYCARBONATE RESIN MIXTURES CONTAINING TITANIUM DIOXIDE FIELD OF THE INVENTION This invention relates to mixtures of moldable polycarbonate resin which contain titanium dioxide. The invention also relates to injection molding such resin blends and articles obtained therefrom.

BRIEF DESCRIPTION OF THE RELATED ART Thermoplastic flame retardant resin compositions containing an aromatic polycarbonate resin, an ABS graft copolymer, a fluoropolymer and an organophosphorus flame retardant are known and have been found to have good flame retardancy and good heat resistance.; see, for example, the patent of E.U.A. co-assigned No. 5,204,394. It is also known that it is desirable to incorporate titanium dioxide into various thermoplastic resin blends. The titanium dioxide is incorporated into resin blends as a coloring agent to obtain a desirable appearance.

The prior art, specifically in relation to polycarbonate resins, indicates that a preferred titanium dioxide for use in such resins consists of a plurality of coatings, typically two or three coatings which may comprise a first coat of polysiloxane or polyol, a second coat. silicone-type coating, and / or a third branched polyorganosiloxane with silanol functionality. See, for example, Kronos Titanium Dioxide Plastics, Publication 1993, commercial brochure; and Plastics Compoundinq, November / December 1993, pages 44-46. Said prior art indicates that titanium dioxide with such coatings provides polycarbonate resins with good physical and color properties. Suitable are polycarbonate resin blends compositions incorporating titanium dioxide to impart improved aesthetic appearance, particularly improved scratch resistance. It has been found that titanium dioxide preferred by the prior art, which has a plurality of coatings, results in scraping when blends of polycarbonate resin blends.

BRIEF DESCRIPTION OF THE INVENTION It has been found that by using only titanium dioxide with a coating, the thermoplastic polycarbonate resin blends can be molded with less scraping or essentially no scraping.

The polycarbonate resin compositions of the present invention comprise: (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 rigid copolymer, and (d) titanium dioxide having a first coating and being free of coatings The polycarbonate resin composition of the present invention may also comprise at least one of: (e) a fluoropolymer, (f) a flame retardant amount of an organophosphorus flame retardant, and (g) an impact modifier component. weather-resistant acrylic, as well as conventional additives The invention also relates to a method for making such a polycarbonate resin composition. by mixing the aforementioned components (a), (b), (c) and (d) and optionally at least one of (e), (f) and (g). The method of the invention also relates to the molding of polycarbonate resin compositions, which includes molding the compositions by injection. ^ &SZSg &L tii The invention also relates to the molded articles themselves, which show a very low or substantially no scrape.

DETAILED DESCRIPTION OF THE INVENTION In a preferred embodiment, the thermoplastic resin composition of the present invention comprises, based on 100 parts by weight ("pbw") of thermoplastic resin composition, from 50 to 90 pbw, preferably from 70 to 81 pbw, of the aromatic polycarbonate resin, from 4 to 30 pbw, preferably from 5 to 10 pbw, of the rubber modified graft copolymer, from 2 to 15 pbw, preferably from 5 to 10 pbw, of the rigid copolymer phase, of 5 to 15 pbw, preferably of 8 to 12 pbw of the organophosphorus flame retardant, of 0.2 to 1 pbw, preferably of 0.4 to 0.8 pbw of the fluoropolymer additive, and of 0.3 at 10 pbw, preferably from 0.8 to 2.5 pbw of titanium dioxide. The thermoplastic resin composition may also comprise from 0 to 8 pbw, preferably from 1.0 to 5 pbw of the weather resistant acrylic impact modifier. (a) Aromatic polycarbonate resin The aromatic polycarbonate resins suitable for use as the 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 resin component of aromatic polycarbonate of the present invention is the reaction product of a dihydric phenol according to the structural formula (I): HO-A-OH (I) wherein A is a divalent aromatic radical, with a carbonate precursor, and contains structural units according to the 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 individual aromatic ring urv 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 linked by non-aromatic bonds, such as, for example, an alkylene, alkylidene or Sulfonyl, any of which can be substituted at one or more sites in the aromatic ring with, for example, a halogen group or C-i-Cß alkyl group. In a preferred embodiment, A is a divalent aromatic radical according to formula (III): g g £ !! g (III) The 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'-d, hydroxyphenyl) propane, 2,6-dihydroxy naphthalene, 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, resins of polycarbonate from Ifisjenol A. Branched polycarbonates to emads are known and are obtained by reacting a polyfunctional aromatic compound with a dihydric phenol and a carbonate precursor to form a polymer. branched see, generally, the patents of E.UVtíífos. 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, 1-tri (4-hydroxyphenyl) ethane, 1, 3,5-trihydroxy-benzene, trimellitic anhydride, trimellitic acid, trimellitic trichloride, phthalic anhydride 4-chloroformil, pyromellitic acid, pyromellitic dianhydride, mellitic acid, mellitic anhydride, trimesic acid, benzophenonetracarboxylic acid or benzophenonetracarboxylic dianhydride. The 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 about 200,000 grams per mole ("g / mol"), as determined by gel permeation chromatography relative to polystyrene. Said resins typically exhibit 0.3 to about 1.5 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 are also suitable for use as the polycarbonate resin component of the present invention. The copolyester-carbonate resins suitable for use as the polycarbonate resin component 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 attached directly to the carbon atoms of ring of aromatic carbocyclic groups. In a preferred embodiment, the resin component of The copolyester-carbonate 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): wherein A 'is alkylene, alkylidene, cycloaliphatic or aromatic, and is preferably a phenylene radical not susilSrao 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 the formula (II) above, and second structural units according to the formula (V): O O II II - (O-C-A-C) - (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, softgel acid, terephthalic acid, dimethyl terephthalic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dimethyl malonic acid, acid 1, 12-dodecanoic acid, c / s-1,4 acid, cyclohexanedicarboxylic acid, frans-1, 4-cyclohexanedicarboxylic acid, 4,4'-bisbenzoic acid and naphthalene-2,6-d-carboxylic acid. Suitable dicarboxylic acid equivalents include, for example, anhydride, ester or halide derivatives of dicarboxylic acids ^^^^^^^^^^^^^^^^^^ JMg ^^ i ^^^ to ^^^^^^^^^^^^^^^^ described above such as, for example, phthalic anhydride / dimethyl lerephthalate 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. '1 &'; In a preferred embodiment, the ratio of ester linkages to carbonate linkages present in the copolyester-carbonate resin is 0.25 to 0.9 ester linkages per carbonate linkage. 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. (b) Rubber Modified Thermoplastic Resin Rubber modified thermoplastic resins suitable for use as the rubberized thermoplastic resin of the present invention are those rubber modified thermoplastic resins which are made by an emulsion polymerization process and which comprise a Discontinuous elastomeric phase dispersed in a continuous rigid thermoplastic phase, wherein at least about 40% of the rigid thermoplastic phase is chemically grafted to the elastomeric phase.

Suitable rubbers for use in the manufacture of the elastomeric phase are polymers having a glass transition temperature (Tg) less than or equal to 25EC, more preferably less than or equal to 0EC, and even more preferably less than or equal to -30EC As referred to herein, the Tg of a polymer is the Tg value of the polymer, measured by differential scanning calorimetry (heating rate of 20EC / minute, the value of Tg being determined at the inflection point). In a preferred embodiment, the rubber comprises a linear polymer having structural units derived from one or more conjugated diene monomers. Suitable conjugated diene monomers include, for example, 1,3-butadiene, isoprene, 1,3-heptadiene, methyl-1,3-pentadiene, 2,3-dimethylbuadiene, 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. Optionally, the rubber may include structural units derived from one or more monoethylenically unsaturated copolymerizable monomers selected from C2-Cs olefin monomers, vinyl aromatic monomers, monoethylenically unsaturated nitrile monomers, and C-alkyl (meth) acrylate monomers. ? -C? 2 As used herein, the term "C2-Cß olefin monomers" means a compound having from 2 to 8 carbon atoms per molecule and having a single site of ethylenic unsaturation per molecule. Suitable C2-Cβ 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 monomers vinyl aromatics 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. As used herein, the term "CrC-? 2 alkyl" means a linear or branched alkyl substituent group having from 1 to 12 carbon atoms per group, and includes, for example, methyl, ethyl, -butyl, sec-butyl, t-butyl, n-propyl, isopropyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl and dodecyl, and the terminology "(meth) acrylate monomers" refers collectively to acrylate monomers and methacrylate monomers. Suitable C-α-C- alquilo 2 alkyl (meth) acrylate monomers include C?-C-? Alkyl acrylate monomers, for example, ethyl acrylate, butyl acrylate, isopentyl acrylate, acrylate n-hexyl, 2-ethylhexyl acrylate, and its C1-C-12 alkyl methacrylate analogs such as, for example, methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, butyl methacrylate, Hexyl methacrylate and decyl methacrylate. In a first preferred embodiment, the rubber is a polybutadiene homopolymer. The elastomeric phase is made by aqueous emulsion polymerization in the presence of a free radical initiator, a polyacid surfactant, and optionally, an elastomeric phase of an aqueous agent is grafted to the elastomeric phase.

Chain transfer with one or more monovinylidene monomers having a Tg greater than about 90 C and coagulating to form particles of elastomeric phase material. Suitable initiators include 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, potassium persulfate, an azonitrile compound, such as, for example, 2,2'-azobis-2,3,3-trimethylbutyrronitrile, or a redox initiator system, such as for example a combination of eumeno hydroperoxide, ferrous sulfate, tetrasodium pyrophosphate and a reducing sugar or sodium formaldehyde sulfoxylate. Suitable chain transfer agents include, for example, a C9-C13 alkyl mercaptan compound such as nonylmercaptan, t-dodecyl mercaptan.

Suitable surface-active surfactants include soaps of a polycarboxylic acid having from 10 to 108 carbons, preferably from 32 to 60 carbon atoms per molecule. Suitable polycarboxylic acids can be formed by dimerizing a monobasic fatty acid containing ethylenic bonds and from about 14 to about 22 carbon atoms in length. Suitable monobasic fatty acids include, for example, oleic, elaidic, palmitoleic, linoleic, linolenic, lycanic, erucic, cylindrical and elaetearic acids. In commercial practice, natural mixtures of these acids are normally used for the production of dimerized fatty acids. Such acids can be derived from sources such as wood oil, fatty acids, bait fatty acids (animal fat) and vegetable oils, for example soybeans, flaxseed, cotton, and other oils comprising glycerides of unsaturated fatty acid. In cieneral, the dimerization is carried out by heating the monomeric acid to an elevated temperature, with or without a catalyst, while avoiding rupture and decarboxylation. The patents of E.U.A. 2,482,761, 2,664,429, 2,793,219, 2,793,220, 2,955,121, 3,076,003, 3,507,890 and 3,925,342 describe dimerization in more detail. For improved color, the dimerized fatty acids can be partially or completely saturated by hydrogenation in a subsequent reaction step, as described in Chapter 5 entitled "Hydrogenation of Fatty Acids" in the book "Fatty Acids in Industry" edited by Robert Johnson and Earle Fritz and published by Marcel Dekker, Inc. NY, NY. The dimeric acids k suitable are liquids at 25 ° C even * when their weight moleciaia || bromed¡o is usually more than 500g / m * In a preferred embodiment, the polyacid surfactant comprises more than or equal to 50% by weight of one or more fatty acid dimers and trimers. The fatty acids dim | l | s used to prepare the novel compositions of this invention, preferably, comprise a product having no more than about 70% tribasic acid and for very low bleed characteristics no more than 10% monobasic acids. And preferably, no more than 5% in p @ § © of monobasic acid based on the total weight of the polyacid component. The dimerized acid content is preferably at least 75% by weight based on the total weight of the surfactant. Preferred polyacids are acyclic aliphatic polyacids, cyclic aliphatic polyacids and cyclic aromatic polyacids. Preferably, the polyacid is a high molecular weight polyacid having from 30 to 108 carbon atoms and preferably from 32 to 60 carbon atoms. Preferably, the polyacid is soluble and / or miscible in the thermoplastic compositions. Preferably, the polyacid in the form of carboxylate salts of the polyacid function are surfactants, emulsifiers or soaps. Different types of dimerized fatty acids are commercially available and such products normally contain trimerized fatty acids, which are tribasic acids formed as a by-product through the polymerization of three molecules of the fatty acids monobasic Larger polybasic acids such as tetracarboxylic acids (C72) and hexacarboxylic acids (C-ioß) may also be present - In addition, commercial products may contain small percentages of isomerized monobasic acids or monomeric monobasic fatty acids completely saturated or unreacted which are not polymerized or which were not removed after the polymerization was performed. Although dimeric acid surfactants are preferred, other emulsifiers or surfactants can be used. In a preferred embodiment, the polyacid is used in the emulsion polymerization of the elastomeric phase of the rubber modified graft copolymer of the present invention in an amount of about 0.25 to 5% by weight, preferably 0.75 to 3.5% by weight thereof. , preferably from 1.5 to 2.75% by weight, based on 100 parts by weight of butadiene monomer. In a preferred embodiment, the rubber is polymerized in the presence of an amount of a chain transfer agent that is effective to provide a rubber having an expansion ratio in toluene greater than 15, preferably 20 to 150 and preferably 40. to 100. The rate of expansion is measured by immersing approximately 0.2 grams of a cast film of sample composition in approximately 96 milliliters of toluene for 16 hours at room temperature. The rate of expansion is calculated by dividing the weight of the dilated sample by the weight of the dry sample.

In a preferred embodiment, the emulsion polymerized particles of the elastomeric phase material have a weight average particle size of 50 to 180 nanometers ("nm"), preferably 70 to 150 nm, as measured by light transmission. The size of elastomeric particles polymerized by emulsion can optionally be increased through mechanical, colloidal or chemical agglomeration of the emulsion polymerized rubber particles, according to known techniques. The desirable average weight particle size ranges from 70 to 800 nm, preferably a bimodal particle distribution that ranges by about 300 nm. The rigid thermoplastic resin 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 preferably greater than or equal to 100 ° C. In a preferred embodiment, the rigid thermoplastic phase comprises one or more polymers, each having structural units derived from one or more monomers selected from the group consisting of monomers of (meth) alkyl acrylate of C -? - C-? 2, aromatic vinyl monomers and monoethylenically unsaturated nitrile monomers. The monomers of C.sub.1 -C.sub.2 -C.sub.2 alkyl methacrylate, aromatic vinyl monomers and suitable unsaturated monoethylenitrile nitrile monomers are those described above in the description of the elastomeric phase. In a preferred embodiment, the rigid thermoplastic resin phase comprises an aromatic vinyl polymer having first units sa-ag-wr »structural derivatives of one or more aromatic vinyl monomers, preferably styrene, and having second structural units derived from one or more monoethylenically unsaturated nitrile monomers, preferably acrylonitrile. Preferably, the rigid phase comprises from 55 to 99% by weight, preferably 60% by weight of structural units derived from styrene and from 1 to 45% by weight, preferably from 10 to 40% by weight of structural units derivatives of acrylonitrile. 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 25 to 55% by weight, preferably from 45 to 55% by weight, the rigid thermoplastic phase is chemically inserted to the elastomeric phase, and from 45 to 75% by weight, preferably from 40 to 75% by weight. 55% by weight of the rigid thermoplastic phase remains "free" that is, not grafted. Erv a preferred embodiment, one or more rigid polymerized thermoplastic polymers separately for a thermoplastic polymer that has been polymerized in the presence of the elastomeric phase in order to help adjust the viscosity of the composition of the present invention in the desired range. In a more preferred embodiment, the average molecular weight of one or more polymerized rigid thermoplastic polymers separately is from about 50,000 to about 250,000 g / mol. In a preferred embodiment, the rubber modified thermoplastic resin comprises an elastomeric phase comprising a polymer having .v structural units derived from uriiw more diamixed monomers and, optionally, further comprising structural units derived from one or more monomers selected from vinyl aromatic monomers and monoethylenically unsaturated nitrile monomers. In a highly preferred embodiment, the elastomeric phase of the graft copolymer modified with ^ t comprises a polybutadiene rubber or poly (styrene-butadiene) and the rigid grafted phase comprises a styrene-acrylonitrile copolymer. Each of the polymers of the elastomeric phase and of the rigid thermoplastic resin phase of the rubber-modified thermoplastic resin can optionally include, as long as the limitation of Tg of the respective phase is satisfied, up to 10% by weight of third units. Structurally derived from one or more other copolymerizable monomers such as, for example, monoethylenically unsaturated carboxylic acids such as, for example, acrylic acid, methacrylic acid, itaconic acid, C 1 -C 12 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, vinyl esters such as, for example, vinyl acetate and I / jβpo propionate, As used herein, the term "C-C2-cycloalkyl" means a cyclic alkyl substituent group having from 4 to 12 carbon atoms per group, the term "(meth) acrylamide" is SEEN together with acrylamides and methacrylamides. (c) Rigid copolymer The rigid copolymer can be formed from at least two ethylenically unsaturated monomers and is compatible with the graft copolymer. Suitable ethylenically unsaturated monomers, such as vinyl aromatics, vinyl substituted aromatics, acrylonitrile, substituted acrylonitriles, acrylates, methacrylates, alkyl acrylates, alkyl methacrylates, and ethylenically unsaturated carboxylic acids, diacids, dianhydrides, acid esters, diacid esters, amides and N-substituted imides. Preferably, the rigid polymer is formed from at least 2 monomers selected from the group consisting of styrene, alpha-methylstyrene, dibromostyrene, methyl methacrylate, acrylonitrile, maleic anhydride, maleimide, N-phenylmaleimide and acrylamide. Preferably, the rigid copolymer is formed from a first monomer selected from styrene, alpha-methylstyrene, dibromostyrene and methyl methacrylate and at least one other monomer selected from acrylonitrile, methacrylonitrile, methyl methacrylate, maleic anhydride, maleimide, N-phenylmaleimide and Acrylamide In such cases, it is preferred that the rigid copolymer be formed from about 60 to about 95 weight percent of the first monomer and from about 5 to about 40 weight percent of the second monomer. A preferred rigid copolymer comprises styrene and acrylonitrile. The rigid copolymer can be prepared by any method known in the art that includes emulsion, block and suspension polymerization processes, and combinations thereof. Examples of preferred rigid copolymers include the following: styrene-acrylonitrile; styrene-acrylonitrile-maleic anhydride; styrene-alpha-methylstyrene-acrylonitrile; styrene-alpha-methylstyrene-acrylonitrile-N-phenylmaleimide; methacrylate-acrylonitrile styrene-methyl; styrene-methyl methacrylate-acrylonitrile-maleic anhydride; styrene-methyl methacrylate-alfe-methylstyrene-acrylonitrile-N-phenyl maleimide; styrene-methyl methacrylate-acrylonitrile-N-phenyl maleimide; styrene-methylmethacrylate-acrylonitrile-N-phenyl maleimide maleic anhydride; styrene-dibromostyrene-acrylonitrile; styrene-dibromostyrene-acrylonitrile maleic anhydride; styrene-dibrQraoestirTfio-alpha-methylstyrene-acrylonitrile; and styrene-dibromostyrene-acrylonitrile-N-phenyl maleimide. In a preferred embodiment, the rigid copolymer comprises an aromatic vinyl polymer having first structural units derived from one or more vinyl aromatic monomers, preferably styrene, and having second structural units derived from one or more monoethylenically unsaturated nitrile monomers, preferably acrylonitrile. Preferably, the rigid copolymer comprises from about 55 to 99% by weight, preferably 60 to 90% by weight of structural units derived from styrene and from 1 to 45% by weight, preferably 10 to 40% by weight of structural units derived of acrylonitrile. Preferably, such preferred rigid copolymers have an average molecular weight of about 50,000 to 150,000 g / mol.

Fluoropolymer Additive In a preferred embodiment, the composition of the present invention includes a fluoropolymer. Typically, the fluoropolymer is provided in an amount of 0.01 to 1.0 pbw of fluoropolymer per 100 pbw of the thermoplastic resin composition, which is effective to provide anti-drip properties to the resin composition. 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 that comprise structural units derived from one or more fluorinated "-olefin monomers." The term "fluorinated olefin" monomer means an "-olefin monomer that includes at least one atom substituent. Fluorine Suitable fluorinated -olefin monomers include, for example, fluoroethylenes such as, for example, CF2 = CF2, CHF = CF2, CH2 = CF2 > CH2 = CHF, CCIF = CF2, CCI2 = CF2, CCIF = CCIF, CHF = CCI2, CH2 = CCIF and CCI2 = CCIF and fluoropropylenes, such as, for example, CF3CF = CF2, CF3CF = CHF, CF3CH = CF2, CF3CH = CH2, CF3CF = CHF, CHF2CH = CHF and CF3CH = CH2. In a preferred embodiment, the fluorinated -olefin monomer is one or more of tetrafluoroethylene (CF2 = CF2), chlorotrichloroethylene, (CCIF = CF2), fluoride and hexopropylene (CF2 = CFCF3). Suitable fluorinated "-olefman homopolymers include, for example, poly (tetrafluoroethylene) and poly (hexrofo-ethylene)." Suitable fluorinated jatene copolymers include copolymers comprising structural units derived from two or more fluorinated -olefin copolymers such as example, poly (tetrafluoroethylene-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, poly (tetrafluoroethylene-) copolymers. ethylene-propylene.) Suitable non-fluorinated monoethylenically unsaturated monomers include, for example, "-olefin monomers such as, for example, ethylene, propylenebutene, acrylate monomers such as, for example, methyl methacrylate, butyl acrylate, ethers vinyl such as, for 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. In a highly preferred embodiment, the fluoropolymer is a poly (tetrafluoroethylene) homopolymer ("PTFE"). Since the direct incorporation of a fluoropolymer in a thermoplastic resin composition tends to be difficult, it is preferred that the fluoropolymer be premixed in some manner with such as, for example, an aromatic polycarbonate resin or a styrene-acrylonitrile resin. For example, an aqueous dispersion of fluoropolymer and a polycarbonate resin can be precipitated by vapor to form a fluoropolymer concentrate to be used as a drip inhibitor additive in a thermoplastic resin composition, such as that described in, for example, the USA No. 5,521, 230 or, alternatively, an aqueous emulsion of styrene-acrylonitrile resin or an aqueous emulsion of acrylonitrile-butadiene-styrene resin and then precipitating and drying the thermoplastic resin composition of co-coagulated fluoropolymer to provide a powder of PTFE thermoplastic resin as described for example in the US patent No. 4,579,906. Other suitable methods for forming a fluoropolymer additive are described, for example, in the patents of > E.U.A. Nos. 5,539,036; 5,679,741 and 5,681, 875. In a preferred embodiment, the fluoropolymer additive comprises from 30 to 70% by weight of PTFE, most preferably 40 to 60% by weight of PTFE and from 30 to 70% by weight, more preferably 40 to 60% by weight of the second polymer , as referenced earlier in this section. 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 C1-C12 alkyl (meth) acrylate monomers. vinyl aromatic monomers, monoethylenically unsaturated nitrile monomer and C 1 -C 12 alkyl (meth) acrylate monomers are described above. In a highly preferred modality, 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. 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.

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 structural formula (VI): wherein Ri, R2, R3 and R4 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 on the one or more aromatic rings with one or more alkyl groups, each preferably Ci-Cß alkyl. As used herein, "arylene" means a divalent radical containing one or more aromatic rings per radical, which may be optionally substituted on the one or more aromatic rings with one or more alkyl groups, each preferably being C- alkyl? -C6 and which, in the case where the divalent radical contains two or more rings, the rings can be fused or can be bound by non-aromatic bonds, such as, for example, an alkylene, alkylidene, any of which can be substituted in one or more sites in the aromatic ring with a halogen group or alkyl group In a highly preferred embodiment, Ri, R2, R3 and * are each phenyl, a, b, c and d are each 1 and X is phenylene, very preferably 1,3-phenylene. In an alternative and highly preferred embodiment, R-i, R2, R3 and R4 are each phenyl, a, b, c and d are each 1 and X is a divalent radical according to the structural formula (VII): 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 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. (f) Titanium dioxide Inorganic treatments which are present in a variety of titanium dioxides are hydrated alumina, silicon dioxide, sodium silicates, sodium aluminates, aluminosilicate silicates, zinc oxide, zirconium oxide and mica. These are used as building blocks in the construction of the titanium dioxide particle. They can be precipitated selectively so that they occur near the surface in the individual particles. These treatments are typically used as dispersion aids and neutralization agents. In addition, raw or treated titanium dioxide particles can be coated with organic surface coatings such as silicone oil, alkyl silane compounds, alkyl acid polysiloxanes, polyorganosiloxanes, alcohols or polyols, alkyl phosphates or phosphorylated fatty acids. In addition, specialized coatings may be incorporated such as titanate coupling agents (eg, isopropyl triisostearoyl titanate). The thermoplastic resin composition of the invention contains a modified surface titanium dioxide having a first coating and being free of additional coatings. A suitable first coating material is for example, a polyol. A preferred polyol is trimethylol propane. Another suitable first coating material is, for example, a polysiloxane. A preferred polysiloxane is polydimethylsiloxane. The titanium dioxide is free of additional coatings, such as additional coatings of silbona and silanol. (q) Weather resistant acrylic impact modifiers In a preferred embodiment, the thermoplastic resin composition includes a weather resistant acrylic impact modifier. Suitable weather-resistant acrylic impact modifiers include, for example, polyorganosiloxane, polybutalacrylate, 2-ethylhexylacrylate and mixtures thereof, grafted to a poly (methyl methacrylate) homopolymer or acrylate or styrene copolymer and acrylonitrile. Preferably, the weather-resistant acrylic impact modifier comprises from about 50 to 80% by weight of rubber component and from about 20 to 50% by weight of grafted phase.

Additives The composition of resin- | érmoplástica of the present invention may also optionally contain various conventional additives such as antioxidants, such as organophosphites, eg, tris (nonylphenyl) phosphite, (2,4,6-tri- terbutylphenyl) (2-butyl-2-ethyl-1,3-propanediol) phosphite, bios (2,4-di-t-butylphenyl) pentaerythritol diphosphite or distearyl pentaerythritol diphosphite, as well as polyphenols, alkylated monophenols , alkylated reaction products of polyphenols with dienes, such as, for example, butylated reaction products of para-cresol and dicyclopentadiene, alkylated hydroquinones, hydroxylated thiodiphenyl ethers, alkylidene bisphenols, benzyl compounds, aminophenols, beta-beta esters (3,5-di-tertbutyl-4-hydroxyphenyl) -propiópico with monohydric or polyhydric alcohols, esters of beta- (5-tertbutyl-4-hydroxy-3-methylphenyl) -propionic acid with monohydric or polyhydric alcohols, acid esters beta- (5-terbut il-4-hydroxy-3-methylphenyl) -propionic with mono- or polyhydric alcohols, thioalkyl esters or thioaryl compounds, such as for example, diasteretylthiopropionate, dilaurylthiopropionate, ditridecylthiodipropionate, beta- (5-tert-butyl-4-amides) -hydroxy-3-methylphenyl) -propionic acid; UV absorbers and light stabilizers such as, for example, (i) 2- (2'-hydroxyphenyl) -benzotriazoles, 2-hydroxybenzophenones; (I) esters of substituted and unsubstituted benzoic acids, (iii) acrylates, hydrotalcite; impact modifiers; fillers and reinforcing agents, such as, for example, silicates, glass fibers, carbon black, graphite, calcium carbonate, talc, mica; and other additives ^ í ^^^^^ | > t | p¡B ^ ^ ^ setal FRJ for example, lubricants such as pentaerythritol tetrastearate, oligomeric propylene oxide and ethylene oxide, silicone fluids, plasticizers, optical brighteners, pigments, dyes tested surfactants of flames, antistatic agents; and blowing agents, as well as other flame retardants in addition to the flame retardant organophosphoric and fluoropolymer described above. 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 mixing using, for example, a two-roll mill, a Banbury mixer or a twin worm or individual worm extruder, and, optionally, then reducing the composition thus formed to particulate form, for example, by compressing or spraying the composition. The composition termopláetsca resin gives the present invention can be molded to create shaped articles useful by a variety of means such as injection molding, extrusion, rotational molding, blow molding and thermoforming to form articles such as, for example, cases for computers and home machines, and household appliances.

^? ^? ¡I? S ^ A ^^ EXAMPLES Examples 1-5 and Comparative Examples C1-C5 The respective thermoplastic resin compositions of the examples of the present invention were each made by combining the components described below in relative amounts (each expressed in parts by weight). The components used in the thermoplastic resin compositions were the following: PC-1 Linear polycarbonate resin having an absolute weight average molecular weight of about 30,000 g / mol; PC-2 Linear polycarbonate resin having an absolute weight average molecular weight of about 22,000 g / mol; PC-3 Linear polycarbonate resin having an absolute weight average molecular weight of about 27,500 g / mol; SAN-1 Copolymer of 75% by weight of styrene and 25% by weight of acrylonitrile having a relative weight average molecular weight of about 60,000 g / mol; SAN-2 Copolymer 75% by weight styrene and 25% by weight acrylonitrile having a relative weight average molecular weight of approximately 77,000 g / mol; SAN-3 Copolymer of 75 wt.% Styrene and 255 wt. Acrylonitrile having a relative weight average molecular weight of about 95,000 g / mol; ABS HRG A rubber graft copolymer prepared by grafting a styrene-acrylonitrile copolymer onto a butadiene rubber in a weight ratio of 50/50; FR Flame retardant organophosphoric; WA-IM Weather resistant acrylic impact modifier; PTFE-MB Additive made by copolymerizing styrene and acrylonitrile in the presence of an aqueous dispersion of PTFE (50 pbw PTFE, 50 pbw of a styrene-acrylonitrile copolymer containing 75% by weight of styrene and 25% by weight of acrylonitrile); LUB Lubricant; T02-1 Titanium dioxide particles purchased from SCM under the trade name RCL69 and comprising approximately 97% by weight of titanium dioxide and 1.5% by weight of alumina. The particles are coated with a first coating of about 0.33% by weight of polydimethylsiloxane and a second coating of about 1.0% by weight of a silicone hydride fluid and a third coating of about 1.1% by weight of a branched silanol fluid, all weights based on the total particle weight; TÍ02-2 Particles of titanium dioxide purchased from DuPont Co. under the trade name R103. The particles comprise approximately 96% by weight of titanium dioxide and approximately 3.2% by weight of alumina.

The particles are coated with a first coating of about 0.25% by weight (based on weight * of particle) of polyol coating without additional surface coating; and Pigments organic and inorganic coloring components. The mixtures were prepared by combining the components in a Henshel mixer for about one minute, and then the mixture was added into the hopper of an extruder. In a typical small-scale laboratory experiment, a six-barreled 30mm Welding Engineers extruder was used to combine these mixtures at 320-400 rpm with a melting temperature of approximately 287.7 ° C. The combined materials were injection molded at approximately 273.8 ° C to form sample plates. All the thermoplastic resin compositions were then classified as to scrape based on visual examination. The appearance of the injection molded plates was evaluated by 3 to 5 operators who classified 5 sample plates of each composition on a scale of 0 to 5, with lower numbers indicating less scrap and larger numbers indicating comparatively more scrapes. The values for all the samples of each composition were added and the sums were normalized each by dividing each sum by the number of samples evaluated (number of samples = 5 X (number of operators)) to obtain the average scrap values reported for each of the compositions in Table 1 below. The different components of each resin composition are provided in percent by weight, based on the total weight of the resin composition.

In addition, examples 1-3 and C1-C3 were compared when taking spectrophotometric measurements. The digital displacement measurements dL were made with a fiber optic probe spectrophotometer. The value L * of the scrape was measured and compared with the base color of the plate following the scrap that is measured. The difference, dL, is equal to L in the scrape minus L in the base color. Several samples were taken from each example and averaged to arrive at the displacement values dL shown below in table 1. The examples clearly show that thermoplastic resins containing titanium dioxide with a first coating, and without any additional coating, they result in a reduced scrap when molded in comparison with thermoplastic resins containing titanium dioxide with a first coating and at least one additional coating comprising silicone.

TABLE 1 C1 C2 C3 C4 C5 1 2 3 4 5 PC-1 44.03 44.03 44.03 - - 44.03 44.03 44.03 ~ - PC-2 29.36 29.36 29.36 ~ ~ 29.36 29.36 29.36 - ~ PC-3 ~ - ~ 70.05 70.05 - ~ ~ 70.05 70.05 SAN-1 8.8 - - - ~ 8.8 - - - ~ SAN-2 - 8.8 ~ - - - 8.8 - - - SAN-3 - - 8.8 8.3 8.3 - - 8.8 8.3 8.3 ABSHRG 6.5 6.5 6.5 9 9 6.5 6.5 6.5 9 9 FR 9.5 9.5 9.5 11.5 11.5 9.5 9.5 9.5 11.5 1 1.5 WA-IM 1 1 1 - - 1 1 1 - - Pl r-kJ B 0.5 0.5 0.5 0.4 0.4 0.5 0.5 0.5 0.4 0.4 Stabilizes 0.16 0.08 0.08 0.25 0.25 0.08 0.08 0.08 0.25 0.25 LUB. 0.15 0.15 0.15 0.5 0.5 0.15 0.15 0.15 0.5 0.5 Ti02-1 1.5 1.5 1.5 2.36 4.72 - - - - - Ti02-1 - - - - - 1.5 1.5 1.5 2.36 4.72 RgmeptDS 0.0842 0.0842 0.0842 0.1374 02748 0.0842 0.0842 0.0842 0.1374 02748 Scrape 3.2 2.92 1.78 3.27 3.87 1.47 0.93 0.80 1.53 3.47 Vata- from 0.54 0.38 0.33 - 0.27 0.20 0.21 despbzamerto cL prcrnsdb Although the above discussion includes a very particular description, one skilled in the art may think of different modifications to the description, and all such modifications should be considered within the scope of the claims appended thereto. "1U - • - l« fc lfr ^ 3i ^^^^^^ tfí t rtiíi ^ a

Claims (25)

NOVELTY OF THE INVENTION CLAIMS

1. - A scratch resistant, injection moldable 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, in wherein at least a portion of the rigid thermoplastic phase is chemically grafted to the elastomeric phase, (c) a rigid copolymer, and (d) a treated or raw surface modified titanium dioxide having a first organic surface coating and which is free of additional coatings.

2. The composition according to claim 1, further characterized in that said first coating comprises a coating selected from the group consisting of polyol and polysiloxane.

3. The composition according to claim 2, further characterized in that said polyol comprises trimethylol propane.

4. The composition according to claim 2, further characterized in that said polysiloxane comprises polydimethylsiloxane.

5. The composition according to claim 1, further comprising a fluoropolymer.

6. - The composition according to claim 5, further comprising a flame retardant amount of an organophosphorus flame retardant.

7. The composition according to claim 6, further characterized in that the composition comprises, based on 100 parts by weight of the thermoplastic resin composition, of about 50 to 90 parts by weight of the aromatic polycarbonate resin, of about 4 to 30 parts by weight of rubber-modified graft copolymer, from about 2 to 15 parts by weight of rigid copolymer, from about 0.2 to 1.0 parts by weight of fluoropolymer, from 5 to 15 parts by weight of flame retardant organophosphorus and 0.3 to 10 parts by weight of titanium dioxide.

8. The composition according to claim 7, further characterized in that the composition comprises, based on 100 parts by weight of the thermoplastic resin composition, of about 70 to 81 parts by weight of the aromatic polycarbonate resin, of about 5 to 10 parts by weight of rubber-modified graft copolymer, from about 5 to 10 parts by weight of rigid copolymer, from about 0.4 to 0.8 parts by weight of fluoropolymer, from 8 to 12 parts by weight of flame retardant organophosphorus and from 0.8 to 2.5 parts by weight of titanium dioxide.

9. The composition according to claim 1, further comprising a weather resistant acrylic impact modifier.

10. - The composition according to claim 9, further characterized in that said weather-resistant acrylic impact modifier comprises less than about 5 parts by weight of the total weight of the thermoplastic resin composition.

11. The composition according to claim 10, further characterized in that said weather-resistant acrylic impact modifier comprises from about 1.0 to 5.0 parts by weight of the total weight of the thermoplastic resin composition.

12. The composition according to claim 1, further characterized in that the elastomeric phase of the rubber-modified graft copolymer comprises a dimer-based surfactant.

13. The composition according to claim 1, further characterized in that the polycarbonate resin is derived from bisphenol A and phosgene.

14. The composition according to claim 1, further characterized in that the elastomeric phase comprises a butadiene polymer or a copolymer of poly (styrene-butadiene) and the rigid thermoplastic phase comprises structural units derived from one or more monomers selected from monomers vinyl aromatics and a monoethylenically unsaturated nitrile monomer.

15. The composition according to claim 14, further characterized in that the rigid phase comprises a copolymer derived ^^^^^^^^^^^^^ SBí ^^ of monomers selected from the group consisting of styrene, "-methylstyrene and acrylonitrile

16. The composition according to claim 8, further characterized in that the rigid copolymer it comprises styrene and acrylonitrile monomers with the composition ratio being between 60 to 90 weight percent to 10 to 40 weight percent

17. The composition according to claim 8, further characterized in that the rigid copolymer comprises at least about 85 weight percent methyl methacrylate and the remaining comonomers are ethyl acrylate, acrylonitrile, styrene, methyl methacrylate or mixtures thereof

18. The composition according to claim 6, further characterized in that the retardant of organophosphoric flame comprises one or more compounds according to the structural formula: wherein R-i, R2, R3 and R4 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.

19. - The composition according to claim 5, further characterized in that the fluoropolymer is provided in an amount effective to provide anti-drip properties to the composition.

20. The composition according to claim 19, further characterized in that the fluoropolymer is a tetrafluoroethylene polymer.

21. The composition according to claim 19, further characterized in that the fluoropolymer is added to the composition in the form of an additive made by emulsion polymerization of one or more monoethylenically unsaturated monomers in the presence of an aqueous dispersion of the fluoropolymer.

22. The composition according to claim 21, further characterized in that the additive is made by emulsion polymerization of styrene and acrylonitrile in the presence of an aqueous dispersion of polytetrafluoroethylene particles.

23. An article made when molding the composition of claim 1. 24.- The article according to claim 23, further characterized in that said molding is injection molding. 25. A method for injection molding the composition of claim 1, said method results in molded articles that essentially have no scraping.