Thermoplastic Polycarbonate Compositions With Improved Static Resistance

BACKGROUND

This invention is directed to thermoplastic compositions comprising an aromatic polycarbonate copolymer, and in particular thermoplastic polycarbonate compositions having improved static resistance.

Thermoplastics having good static resistance (anti-dust properties) are useful in the manufacture of molded articles and components for a wide range of applications, from automobile components, to decorative articles, to housings for electronic appliances, such as computers and cell phones. This is particularly true of thermoplastics used in molded articles such as equipment housings, where it is important to have dust resistance or the avoidance of static charges that pick up dust during molding, assembly and transportation. It is known to add various surfactants to reduce static or surface charges, but the addition of surfactants to impact modified compositions often reduces mechanical properties, such as impact strength, and leads to reduced or poor flame performance.

There accordingly remains a need in the art for thermoplastic polycarbonate compositions having improved static or dust resistance. Desirable features of such materials also include both excellent mechanical properties and flame performance as well as ease of manufacture. The mechanical properties of the thermoplastic composition with improved static resistance are desirably comparable to those of other thermoplastic polycarbonate compositions.

SUMMARY

The above needs are met by a thermoplastic composition comprising an aromatic polycarbonate; an impact modifier; a flame retardant; and from 0.9 to 5.38 mol of an anti-static additive having the formula

wherein X is independently selected from halogen or hydrogen provided that at least one X is halogen; n, m and p are integers from 0 to 12; and Y is zero or a heterocyclic atom, other than carbon, of an atomic ring and is either nitrogen, oxygen, sulfur, selenium, phosphorus, arsenic, and the like; R₁, R₂, and R₃are the same, each having an aliphatic hydrocarbon radical with 1 to 8 carbon atoms or an aromatic hydrocarbon radical of 6 to 12 carbon atoms and R₄is a hydrocarbon radical with 1 to 18 carbon atoms; wherein the amount of the anti-static additive is based on 100 kg of the composition.

In another embodiment, a thermoplastic composition comprises from 50 to 98 wt. % of an aromatic polycarbonate; from 1 to 30 wt. % of an impact modifier; from 1 to 20 wt. % of a flame retardant; and from 0.9 to 5.38 mol of an anti-static additive having the formula

In another embodiment, a thermoplastic composition comprises from 50 to 97.9 wt. % of an aromatic polycarbonate; from 1 to 30 wt. % of an impact modifier comprising ABS or bulk ABS; from 1 to 20 wt. % of a phosphorous containing flame retardant; from 0. 1 to 2 wt. % TSAN; and from 0.9 to 5.38 mol of an anti-static additive, wherein the anti-static additive is tetrabutylphosphonium perfluorobutylsulfonate; wherein the amount of the anti-static additive is based on 100 kg of the composition.

In another embodiment, an article comprises the above-described thermoplastic composition.

One method for forming an article comprises molding, extruding, shaping or forming the composition to form the article.

The above-described and other features are exemplified by the following detailed description.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a bar chart showing the surface resistivity of samples of Examples 1, 2 and 3.

FIG. 2 is a photograph of a molded chip of Example 1 after 45 days exposure in an open office area.

FIG. 3 is a photograph of a molded chip of Example 2 after 45 days exposure in an open office area.

FIG. 4 is a photograph of a molded chip of Example 3 after 45 days exposure in an open office area.

DETAILED DESCRIPTION

Surprisingly, it has been found that a thermoplastic composition comprising n aromatic polycarbonate; an impact modifier; a flame retardant; and from 0.9 to 5.38 mol, based on 100 kg of the composition, of an anti-static additive static resistant. Articles prepared from the thermoplastic composition are static resistant, have excellent flame retardant properties as well as good mechanical properties. In some embodiments, the thermoplastic composition is capable of achieving a UL94 V0 rating at 1.5 mm. In some embodiments, a molded sample consisting of the composition has a surface resistivity of less than or equal to 2E+15 ohms/cm².

In an embodiment, a thermoplastic composition comprises a thermoplastic composition comprising an aromatic polycarbonate; an impact modifier; a flame retardant; and from 0.9 to 5.38 mol of an anti-static additive having the formula

In another embodiment, a thermoplastic composition comprises from 50 to 97.9 wt. % of an aromatic polycarbonate; from 1 to 30 wt. % of an impact modifier comprising ABS or bulk ABS; from 1 to 20 wt. % of a phosphorous containing flame retardant; from 0.1 to 2 wt. % TSAN; and from 0.9 to 5.38 mol of an anti-static additive, wherein the anti-static additive is tetrabutylphosphonium perfluorobutylsulfonate; wherein the amount of the anti-static additive is based on 100 kg of the composition.

As used herein, “static resistant” means resistance to static electricity, which could be characterized by surface resistivity, which is measured according to ASTM D257. A composition or article may be characterized as static resistant if the surface resistivity level is less than or equal to 2E+15 ohms/cm², optionally less than or equal to 1E+14 ohms/cm².

The thermoplastic composition comprises a polycarbonate. As used herein, the term “polycarbonate” refers to a polymer comprising the same or different carbonate units, or a copolymer that comprises the same or different carbonate units, as well as one or more units other than carbonate (i.e. copolycarbonate); the term “aliphatic” refers to a hydrocarbon radical having a valence of at least one comprising a linear or branched array of carbon atoms which is not cyclic; “aromatic” refers to a radical having a valence of at least one comprising at least one aromatic group; “cycloaliphatic” refers to a radical having a valence of at least one comprising an array of carbon atoms which is cyclic but not aromatic; “alkyl” refers to a straight or branched chain monovalent hydrocarbon radical; “alkylene” refers to a straight or branched chain divalent hydrocarbon radical; “alkylidene” refers to a straight or branched chain divalent hydrocarbon radical, with both valences on a single common carbon atom; “alkenyl” refers to a straight or branched chain monovalent hydrocarbon radical having at least two carbons joined by a carbon-carbon double bond; “cycloalkyl” refers to a non-aromatic alicyclic monovalent hydrocarbon radical having at least three carbon atoms, with at least one degree of unsaturation; “cycloalkylene” refers to a non-aromatic alicyclic divalent hydrocarbon radical having at least three carbon atoms, with at least one degree of unsaturation; “aryl” refers to a monovalent aromatic benzene ring radical, or to an optionally substituted benzene ring system radical system fused to at least one optionally substituted benzene rings; “aromatic radical” refers to a radical having a valence of at least one comprising at least one aromatic group; examples of aromatic radicals include phenyl, pyridyl, furanyl, thienyl, naphthyl, and the like; “arylene” refers to a benzene ring diradical or to a benzene ring system diradical fused to at least one optionally substituted benzene ring; “alkylaryl” refers to an alkyl group as defined above substituted onto an aryl as defined above; “arylalkyl” refers to an aryl group as defined above substituted onto an alkyl as defined above; “alkoxy” refers to an alkyl group as defined above connected through an oxygen radical to an adjoining group; “aryloxy” refers to an aryl group as defined above connected through an oxygen radical to an adjoining group; the modifier “about” used in connection with a quantity is inclusive of the stated value and has the meaning dictated by the context (e.g., includes the degree of error associated with measurement of the particular quantity); “optional” or “optionally” means that the subsequently described event or circumstance may or may not occur, or that the subsequently identified material may or may not be present, and that the description includes instances where the event or circumstance occurs or where the material is present, and instances where the event or circumstance does not occur or the material is not present; and “direct bond”, where part of a structural variable specification, refers to the direct joining of the substituents preceding and succeeding the variable taken as a “direct bond”.

Compounds are described herein using standard nomenclature. For example, any position not substituted by any indicated group is understood to have its valency filled by a bond as indicated, or a hydrogen atom. A dash (“−”) that is not between two letters or symbols is used to indicate a point of attachment for a substituent. For example, —CHO is attached through the carbon of the carbonyl (C═O) group. The singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. The endpoints of all ranges reciting the same characteristic or component are independently combinable and inclusive of the recited endpoint. All references are incorporated herein by reference. The terms “first,” “second,” and the like herein do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. The modifier “about” used in connection with a quantity is inclusive of the stated value and has the meaning dictated by the context (e.g., includes the degree of error associated with measurement of the particular quantity).

As used herein, the terms “polycarbonate” and “polycarbonate resin” mean compositions having repeating structural carbonate units of the formula (1):

in which at least about 60 percent of the total number of R¹groups are aromatic organic radicals and the balance thereof are aliphatic, alicyclic, or aromatic radicals. In one embodiment, each R¹is an aromatic organic radical, for example a radical of the formula (2):

A¹-Y¹-A²- (2)

wherein each of A¹and A²is a monocyclic divalent aryl radical and Y¹is a bridging radical having one or two atoms that separate A¹from A². In an exemplary embodiment, one atom separates A¹from A². Illustrative non-limiting examples of radicals of this type are —O—, —S—, —S(O)—, —S(O₂)—, —C(O)—, methylene, cyclohexyl-methylene, 2-[2.2.1]-bicycloheptylidene, ethylidene, isopropylidene, neopentylidene, cyclohexylidene, cyclopentadecylidene, cyclododecylidene, and adamantylidene. The bridging radical Y¹may be a hydrocarbon group or a saturated hydrocarbon group such as methylene, cyclohexylidene, or isopropylidene.

Polycarbonates may be produced by the interfacial reaction of dihydroxy compounds having the formula HO—R¹—OH, wherein R¹is as defined above. Dihydroxy compounds suitable in an interfacial reaction include the dihydroxy compounds of formula (A) as well as dihydroxy compounds of formula (3)

HO-A¹-Y¹-A²-OH (3)

wherein Y¹, A¹and A²are as described above. Also included are bisphenol compounds of general formula (4):

wherein R^aand R^beach represent a halogen atom or a monovalent hydrocarbon group and may be the same or different; p and q are each independently integers of 0 to 4; and X^arepresents one of the groups of formula (5):

wherein R^cand R^deach independently represent a hydrogen atom or a monovalent linear or cyclic hydrocarbon group and R^eis a divalent hydrocarbon group.

Some illustrative, non-limiting examples of suitable dihydroxy compounds include the following: resorcinol, 4-bromoresorcinol, hydroquinone, 4,4′-dihydroxybiphenyl, 1,6-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, bis(4-hydroxyphenyl)methane, bis(4-hydroxyphenyl)diphenylmethane, bis(4-hydroxyphenyl)-1-naphthylmethane, 1,2-bis(4-hydroxyphenyl)ethane, 1,1-bis(4-hydroxyphenyl)-1-phenylethane, 2-(4-hydroxyphenyl)-2-(3-hydroxyphenyl)propane, bis(4-hydroxyphenyl)phenylmethane, 2,2-bis(4-hydroxy-3-bromophenyl)propane, 1,1-bis(hydroxyphenyl)cyclopentane, 1,1-bis(4-hydroxyphenyl)cyclohexane, 1,1-bis(4-hydroxyphenyl)isobutene, 1,1-bis(4-hydroxyphenyl)cyclododecane, trans-2,3-bis(4-hydroxyphenyl)-2-butene, 2,2-bis(4-hydroxyphenyl)adamantine, (alpha, alpha-bis(4-hydroxyphenyl)toluene, bis(4-hydroxyphenyl)acetonitrile, 2,2-bis(3-methyl-4-hydroxyphenyl)propane, 2,2-bis(3-ethyl-4-hydroxyphenyl)propane, 2,2-bis(3-n-propyl-4-hydroxyphenyl)propane, 2,2-bis(3-isopropyl-4-hydroxyphenyl)propane, 2,2-bis(3-sec-butyl-4-hydroxyphenyl)propane, 2,2-bis(3-t-butyl-4-hydroxyphenyl)propane, 2,2-bis(3-cyclohexyl-4-hydroxyphenyl)propane, 2,2-bis(3-allyl-4-hydroxyphenyl)propane, 2,2-bis(3-methoxy-4-hydroxyphenyl)propane, 2,2-bis(4-hydroxyphenyl)hexafluoropropane, 1,1-dichloro-2,2-bis(4-hydroxyphenyl)ethylene, 1,1-dibromo-2,2-bis(4-hydroxyphenyl)ethylene, 1,1-dichloro-2,2-bis(5-phenoxy-4-hydroxyphenyl)ethylene, 4,4′-dihydroxybenzophenone, 3,3-bis(4-hydroxyphenyl)-2-butanone, 1,6-bis(4-hydroxyphenyl)-1,6-hexanedione, ethylene glycol bis(4-hydroxyphenyl)ether, bis(4-hydroxyphenyl)ether, bis(4-hydroxyphenyl)sulfide, bis(4-hydroxyphenyl)sulfoxide, bis(4-hydroxyphenyl)sulfone, 9,9-bis(4-hydroxyphenyl)fluorine, 2,7-dihydroxypyrene, 6,6′-dihydroxy-3,3,3′,3′-tetramethylspiro(bis)indane (“spirobiindane bisphenol”), 3,3-bis(4-hydroxyphenyl)phthalide, 2,6-dihydroxydibenzo-p-dioxin, 2,6-dihydroxythianthrene, 2,7-dihydroxyphenoxathin, 2,7-dihydroxy-9,10-dimethylphenazine, 3,6-dihydroxydibenzofuran, 3,6-dihydroxydibenzothiophene, and 2,7-dihydroxycarbazole, and the like, as well as combinations comprising at least one of the foregoing dihydroxy compounds.

Specific examples of the types of bisphenol compounds that may be represented by formula (3) include 1,1-bis(4-hydroxyphenyl)methane, 1,1-bis(4-hydroxyphenyl)ethane, 2,2-bis(4-hydroxyphenyl)propane (hereinafter “bisphenol A” or “BPA”), 2,2-bis(4-hydroxyphenyl)butane, 2,2-bis(4-hydroxyphenyl)octane, 1,1-bis(4-hydroxyphenyl)propane, 1,1-bis(4-hydroxyphenyl)n-butane, 2,2-bis(4-hydroxy-1-methylphenyl)propane, and 1,1-bis(4-hydroxy-t-butylphenyl)propane. Combinations comprising at least one of the foregoing dihydroxy compounds may also be used.

Branched polycarbonates are also useful, as well as blends of a linear polycarbonate and a branched polycarbonate. The branched polycarbonates may be prepared by adding a branching agent during polymerization. These branching agents include polyfunctional organic compounds containing at least three functional groups selected from hydroxyl, carboxyl, carboxylic anhydride, haloformyl, and mixtures of the foregoing functional groups. Specific examples include trimellitic acid, trimellitic anhydride, trimellitic trichloride, tris-p-hydroxy phenyl ethane, isatin-bis-phenol, tris-phenol TC (1,3,5-tris((p-hydroxyphenyl)isopropyl)benzene), tris-phenol PA (4(4(1,1-bis(p-hydroxyphenyl)-ethyl)alpha, alpha-dimethyl benzyl)phenol), 4-chloroformyl phthalic anhydride, trimesic acid, and benzophenone tetracarboxylic acid. The branching agents may be added at a level of about 0.05 wt. % to about 2.0 wt. %. All types of polycarbonate end groups are contemplated as being useful in the polycarbonate composition, provided that such end groups do not significantly affect desired properties of the thermoplastic compositions.

“Polycarbonates” and “polycarbonate resins” as used herein further includes blends of polycarbonates with other copolymers comprising carbonate chain units. A specific suitable copolymer is a polyester carbonate, also known as a copolyester-polycarbonate. Such copolymers further contain, in addition to recurring carbonate chain units of the formula (1), repeating units of formula (6)

wherein D is a divalent radical derived from a dihydroxy compound, and may be, for example, a C_2-10alkylene radical, a C_6-20alicyclic radical, a C_6-20aromatic radical or a polyoxyalkylene radical in which the alkylene groups contain 2 to about 6 carbon atoms, specifically 2, 3, or 4 carbon atoms; and T is a divalent radical derived from a dicarboxylic acid, and may be, for example, a C_2-10alkylene radical, a C_6-20alicyclic radical, a C_6-20alkyl aromatic radical, or a C_6-20aromatic radical.

In one embodiment, D is a C_2-6alkylene radical. In another embodiment, D is derived from an aromatic dihydroxy compound of formula (7):

wherein each R^kis independently a halogen atom, a C_1-10hydrocarbon group, or a C_1-10halogen substituted hydrocarbon group, and n is 0 to 4. The halogen is usually bromine. Examples of compounds that may be represented by the formula (7) include resorcinol, substituted resorcinol compounds such as 5-methyl resorcinol, 5-ethyl resorcinol, 5-propyl resorcinol, 5-butyl resorcinol, 5-t-butyl resorcinol, 5-phenyl resorcinol, 5-cumyl resorcinol, 2,4,5,6-tetrafluoro resorcinol, 2,4,5,6-tetrabromo resorcinol, or the like; catechol; hydroquinone; substituted hydroquinones such as 2-methyl hydroquinone, 2-ethyl hydroquinone, 2-propyl hydroquinone, 2-butyl hydroquinone, 2-t-butyl hydroquinone, 2-phenyl hydroquinone, 2-cumyl hydroquinone, 2,3,5,6-tetramethyl hydroquinone, 2,3,5,6-tetra-t-butyl hydroquinone, 2,3,5,6-tetrafluoro hydroquinone, 2,3,5,6-tetrabromo hydroquinone, or the like; or combinations comprising at least one of the foregoing compounds.

Examples of aromatic dicarboxylic acids that may be used to prepare the polyesters include isophthalic or terephthalic acid, 1,2-di(p-carboxyphenyl)ethane, 4,4′-dicarboxydiphenyl ether, 4,4′-bisbenzoic acid, and mixtures comprising at least one of the foregoing acids. Acids containing fused rings can also be present, such as in 1,4-, 1,5-, or 2,6-naphthalenedicarboxylic acids. Specific dicarboxylic acids are terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid, cyclohexane dicarboxylic acid, or mixtures thereof. A specific dicarboxylic acid comprises a mixture of isophthalic acid and terephthalic acid wherein the weight ratio of terephthalic acid to isophthalic acid is about 10:1 to about 0.2:9.8. In another specific embodiment, D is a C_2-6alkylene radical and T is p-phenylene, m-phenylene, naphthalene, a divalent cycloaliphatic radical, or a mixture thereof. This class of polyester includes the poly(alkylene terephthalates).

In one specific embodiment, the polycarbonate is a linear homopolymer derived from bisphenol A, in which each of A¹and A²is p-phenylene and Y¹is isopropylidene.

Suitable polycarbonates can be manufactured by processes such as interfacial polymerization and melt polymerization. Although the reaction conditions for interfacial polymerization may vary, an exemplary process generally involves dissolving or dispersing a dihydric phenol reactant in aqueous caustic soda or potash, adding the resulting mixture to a suitable water-immiscible solvent medium, and contacting the reactants with a carbonate precursor in the presence of a suitable catalyst such as triethylamine or a phase transfer catalyst, under controlled pH conditions, e.g., about 8 to about 10. The most commonly used water immiscible solvents include methylene chloride, 1,2-dichloroethane, chlorobenzene, toluene, and the like. Suitable carbonate precursors include, for example, a carbonyl halide such as carbonyl bromide or carbonyl chloride, or a haloformate such as a bishaloformate of a dihydric phenol (e.g., the bischloroformates of bisphenol A, hydroquinone, or the like) or a glycol (e.g., the bishaloformate of ethylene glycol, neopentyl glycol, polyethylene glycol, or the like). Combinations comprising at least one of the foregoing types of carbonate precursors may also be used.

Among the phase transfer catalysts that may be used are catalysts of the formula (R³)₄Q⁺X, wherein each R³is the same or different, and is a C_1-10alkyl group; Q is a nitrogen or phosphorus atom; and X is a halogen atom or a C_1-8alkoxy group or C_6-188aryloxy group. Suitable phase transfer catalysts include, for example, [CH₃(CH₂)₃]₄NX, [CH₃(CH₂)₃]₄PX, [CH₃(CH₂)₅]₄NX, [CH₃(CH₂)₆]₄NX, [CH₃(CH₂)₄]₄NX, CH₃[CH₃(CH₂)₃]₃NX, and CH₃[CH₃(CH₂)₂]₃NX, wherein X is Cl⁻, Br⁻, a C_1-8alkoxy group or a C_6-18effective amount of a phase transfer catalyst may be about 0.1 to about 10 wt. % based on the weight of bisphenol in the phosgenation mixture. In another embodiment an effective amount of phase transfer catalyst may be about 0.5 to about 2 wt. % based on the weight of bisphenol in the phosgenation mixture.

Alternatively, melt processes may be used to make the polycarbonates. Generally, in the melt polymerization process, polycarbonates may be prepared by co-reacting, in amolten state, the dihydroxy reactant(s) and a diaryl carbonate ester, such as diphenyl carbonate, in the presence of a transesterification catalyst in a Banbury® mixer, twin screw extruder, or the like to form a uniform dispersion. Volatile monohydric phenol is removed from the molten reactants by distillation and the polymer is isolated as a molten residue.

The polycarbonate resins may also be prepared by interfacial polymerization. Rather than utilizing the dicarboxylic acid per se, it is possible, and sometimes even preferred, to employ the reactive derivatives of the acid, such as the corresponding acid halides, in particular the acid dichlorides and the acid dibromides. Thus, for example, instead of using isophthalic acid, terephthalic acid, or mixtures thereof, it is possible to employ isophthaloyl dichloride, terephthaloyl dichloride, and mixtures thereof.

In addition to the polycarbonates described above, it is also possible to use combinations of the polycarbonate with other thermoplastic polymers, for example combinations of polycarbonates and/or polycarbonate copolymers with polyesters. As used herein, a “combination” is inclusive of all mixtures, blends, alloys, and the like. Suitable polyesters comprise repeating units of formula (6), and may be, for example, poly(alkylene dicarboxylates), liquid crystalline polyesters, and polyester copolymers. It is also possible to use a branched polyester in which a branching agent, for example, a glycol having three or more hydroxyl groups or a trifunctional or multifunctional carboxylic acid has been incorporated. Furthermore, it is sometime desirable to have various concentrations of acid and hydroxyl end groups on the polyester, depending on the ultimate end use of the composition.

In one embodiment, poly(alkylene terephthalates) are used. Specific examples of suitable poly(alkylene terephthalates) are poly(ethylene terephthalate) (PET), poly(1,4-butylene terephthalate) (PBT), poly(ethylene naphthanoate) (PEN), poly(butylene naphthanoate), (PBN), (polypropylene terephthalate) (PPT), polycyclohexanedimethanol terephthalate (PCT), and combinations comprising at least one of the foregoing polyesters. Also contemplated are the above polyesters with a minor amount, e.g., from about 0.5 to about 10 percent by weight, of units derived from an aliphatic diacid and/or an aliphatic polyol to make copolyesters.

Blends and/or mixtures of more than one polycarbonate may also be used. For example, a high flow and a low flow polycarbonate may be blended together.

The thermoplastic composition further includes one or more impact modifier compositions to increase the impact resistance of the thermoplastic composition. These impact modifiers may include an elastomer-modified graft copolymer comprising (i) an elastomeric (i.e., rubbery) polymer substrate having a Tg less than about 10° C., more specifically less than about −10° C., or more specifically about −40° C. to −80° C., and (ii) a rigid polymeric superstrate grafted to the elastomeric polymer substrate. As is known, elastomer-modified graft copolymers may be prepared by first providing the elastomeric polymer, then polymerizing the constituent monomer(s) of the rigid phase in the presence of the elastomer to obtain the graft copolymer. The grafts may be attached as graft branches or as shells to an elastomer core. The shell may merely physically encapsulate the core, or the shell may be partially or essentially completely grafted to the core.

Suitable materials for use as the elastomer phase include, for example, conjugated diene rubbers; copolymers of a conjugated diene with less than about 50 wt. % of a copolymerizable monomer; olefin rubbers such as ethylene propylene copolymers (EPR) or ethylene-propylene-diene monomer rubbers (EPDM); ethylene-vinyl acetate rubbers; silicone rubbers; elastomeric C_1-8alkyl(meth)acrylates; elastomeric copolymers of C_1-8alkyl(meth)acrylates with butadiene and/or styrene; or combinations comprising at least one of the foregoing elastomers. As used herein, the terminology “(meth)acrylate monomers” refers collectively to acrylate monomers and methacrylate monomers.

Suitable conjugated diene monomers for preparing the elastomer phase are of formula (8):

wherein each X^bis independently hydrogen, C₁-C₅alkyl, or the like. Examples of conjugated diene monomers that may be used are butadiene, isoprene, 1,3-heptadiene, methyl-1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, 2-ethyl-1,3-pentadiene; 1,3- and 2,4-hexadienes, and the like, as well as mixtures comprising at least one of the foregoing conjugated diene monomers. Specific conjugated diene homopolymers include polybutadiene and polyisoprene.

Copolymers of a conjugated diene rubber may also be used, for example those produced by aqueous radical emulsion polymerization of a conjugated diene and one or more monomers copolymerizable therewith. Monomers that are suitable for copolymerization with the conjugated diene include monovinylaromatic monomers containing condensed aromatic ring structures, such as vinyl naphthalene, vinyl anthracene and the like, or monomers of formula (9):

wherein each X^cis independently hydrogen, C₁-C₁₂alkyl, C₃-C₁₂cycloalkyl, C₆-C₁₂aryl, C₇-C₁₂aralkyl, C₇-C₁₂alkaryl, C₁-C₁₂alkoxy, C₃-C₁₂cycloalkoxy, C₆-C₁₂aryloxy, chloro, bromo, or hydroxy, and R is hydrogen, C₁-C₅alkyl, bromo, or chloro. Examples of suitable monovinylaromatic monomers that may be used include styrene, 3-methylstyrene, 3,5-diethylstyrene, 4-n-propylstyrene, alpha-methylstyrene, alpha-methyl vinyltoluene, alpha-chlorostyrene, alpha-bromostyrene, dichlorostyrene, dibromostyrene, tetra-chlorostyrene, and the like, and combinations comprising at least one of the foregoing compounds. Styrene and/or alpha-methylstyrene may be used as monomers copolymerizable with the conjugated diene monomer.

Other monomers that may be copolymerized with the conjugated diene are monovinylic monomers such as itaconic acid, acrylamide, N-substituted acrylamide or methacrylamide, maleic anhydride, maleimide, N-alkyl-, aryl-, or haloaryl-substituted maleimide, glycidyl(meth)acrylates, and monomers of the generic formula (10):

wherein R is hydrogen, C₁-C₅alkyl, bromo, or chloro, and X^dis cyano, C₁-C₁₂alkoxycarbonyl, C₁-C₁₂aryloxycarbonyl, hydroxy carbonyl, or the like. Examples of monomers of formula (10) include acrylonitrile, ethacrylonitrile, methacrylonitrile, alpha-chloroacrylonitrile, beta-chloroacrylonitrile, alpha-bromoacrylonitrile, acrylic acid, methyl(meth)acrylate, ethyl(meth)acrylate, n-butyl(meth)acrylate, t-butyl(meth)acrylate, n-propyl(meth)acrylate, isopropyl(meth)acrylate, 2-ethylhexyl(meth)acrylate, and the like, and combinations comprising at least one of the foregoing monomers. Monomers such as n-butyl acrylate, ethyl acrylate, and 2-ethylhexyl acrylate are commonly used as monomers copolymerizable with the conjugated diene monomer. Mixtures of the foregoing monovinyl monomers and monovinylaromatic monomers may also be used.

Suitable (meth)acrylate monomers suitable for use as the elastomeric phase may be cross-linked, particulate emulsion homopolymers or copolymers of C_1-8alkyl(meth)acrylates, in particular C_4-6alkyl acrylates, for example n-butyl acrylate, t-butyl acrylate, n-propyl acrylate, isopropyl acrylate, 2-ethylhexyl acrylate, and the like, and combinations comprising at least one of the foregoing monomers. The C_1-8alkyl(meth)acrylate monomers may optionally be polymerized in admixture with up to 15 wt. % of comonomers of formulas (8), (9), or (10). Exemplary comonomers include but are not limited to butadiene, isoprene, styrene, methyl methacrylate, phenyl methacrylate, penethylmethacrylate, N-cyclohexylacrylamide, vinyl methyl ether or acrylonitrile, and mixtures comprising at least one of the foregoing comonomers. Optionally, up to 5 wt. % a polyfunctional crosslinking comonomer may be present, for example divinylbenzene, alkylenediol di(meth)acrylates such as glycol bisacrylate, alkylenetriol tri(meth)acrylates, polyester di(meth)acrylates, bisacrylamides, triallyl cyanurate, triallyl isocyanurate, allyl(meth)acrylate, diallyl maleate, diallyl fumarate, diallyl adipate, triallyl esters of citric acid, triallyl esters of phosphoric acid, and the like, as well as combinations comprising at least one of the foregoing crosslinking agents.

The elastomer phase may be polymerized by mass, emulsion, suspension, solution or combined processes such as bulk-suspension, emulsion-bulk, bulk-solution or other techniques, using continuous, semibatch, or batch processes. The particle size of the elastomer substrate is not critical. For example, an average particle size of about 0.001 to about 25 micrometers, specifically about 0.01 to about 15 micrometers, or even more specifically about 0.1 to about 8 micrometers may be used for emulsion based polymerized rubber lattices. A particle size of about 0.5 to about 10 micrometers, specifically about 0.6 to about 1.5 micrometers may be used for bulk polymerized rubber substrates. Particle size may be measured by simple light transmission methods or capillary hydrodynamic chromatography (CHDF). The elastomer phase may be a particulate, moderately cross-linked conjugated butadiene or C_4-6alkyl acrylate rubber, and preferably has a gel content greater than 70%. Also suitable are mixtures of butadiene with styrene and/or C_4-6alkyl acrylate rubbers.

The elastomeric phase may provide about 5 wt. % to about 95 wt. % of the total graft copolymer, more specifically about 20 wt. % to about 90 wt. %, and even more specifically about 40 wt. % to about 85 wt. % of the elastomer-modified graft copolymer, the remainder being the rigid graft phase.

The rigid phase of the elastomer-modified graft copolymer may be formed by graft polymerization of a mixture comprising a monovinylaromatic monomer and optionally one or more comonomers in the presence of one or more elastomeric polymer substrates. The above-described monovinylaromatic monomers of formula (9) may be used in the rigid graft phase, including styrene, alpha-methyl styrene, halostyrenes such as dibromostyrene, vinyltoluene, vinylxylene, butylstyrene, para-hydroxystyrene, methoxystyrene, or the like, or combinations comprising at least one of the foregoing monovinylaromatic monomers. Suitable comonomers include, for example, the above-described monovinylic monomers and/or monomers of the general formula (10). In one embodiment, R is hydrogen or C₁-C₂alkyl, and X^dis cyano or C₁-C₁₂alkoxycarbonyl. Specific examples of suitable comonomers for use in the rigid phase include acrylonitrile, ethacrylonitrile, methacrylonitrile, methyl(meth)acrylate, ethyl(meth)acrylate, n-propyl(meth)acrylate, isopropyl(meth)acrylate, and the like, and combinations comprising at least one of the foregoing comonomers.

The relative ratio of monovinylaromatic monomer and comonomer in the rigid graft phase may vary widely depending on the type of elastomer substrate, type of monovinylaromatic monomer(s), type of comonomer(s), and the desired properties of the impact modifier. The rigid phase may generally comprise up to 100 wt. % of monovinyl aromatic monomer, specifically about 30 to about 100 wt. %, more specifically about 50 to about 90 wt. % monovinylaromatic monomer, with the balance being comonomer(s).

Depending on the amount of elastomer-modified polymer present, a separate matrix or continuous phase of ungrafted rigid polymer or copolymer may be simultaneously obtained along with the elastomer-modified graft copolymer. Typically, such impact modifiers comprise about 40 wt. % to about 95 wt. % elastomer-modified graft copolymer and about 5 wt. % to about 65 wt. % graft (co)polymer, based on the total weight of the impact modifier. In another embodiment, such impact modifiers comprise about 50 wt. % to about 85 wt. %, more specifically about 75 wt. % to about 85 wt. % rubber-modified graft copolymer, together with about 15 wt. % to about 50 wt. %, more specifically about 15 wt. % to about 25 wt. % graft (co)polymer, based on the total weight of the impact modifier.

Another specific type of elastomer-modified impact modifier comprises structural units derived from at least one silicone rubber monomer, a branched acrylate rubber monomer having the formula H₂C═C(R^g)C(O)OCH₂CH₂R^h, wherein R^gis hydrogen or a C₁-C₈linear or branched hydrocarbyl group and Rh is a branched C₃-C₁₆hydrocarbyl group; a first graft link monomer; a polymerizable alkenyl-containing organic material; and a second graft link monomer. The silicone rubber monomer may comprise, for example, a cyclic siloxane, tetraalkoxysilane, trialkoxysilane, (acryloxy)alkoxysilane, (mercaptoalkyl)alkoxysilane, vinylalkoxysilane, or allylalkoxysilane, alone or in combination, e.g., decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane, trimethyltriphenylcyclotrisiloxane, tetramethyltetraphenylcyclotetrasiloxane, tetramethyltetravinylcyclotetrasiloxane, octaphenylcyclotetrasiloxane, octamethylcyclotetrasiloxane and/or tetraethoxysilane.

Exemplary branched acrylate rubber monomers include iso-octyl acrylate, 6-methyloctyl acrylate, 7-methyloctyl acrylate, 6-methylheptyl acrylate, and the like, alone or in combination. The polymerizable alkenyl-containing organic material may be, for example, a monomer of formula (9) or (10), e.g., styrene, alpha-methylstyrene, acrylonitrile, methacrylonitrile, or an unbranched (meth)acrylate such as methyl methacrylate, 2-ethylhexyl methacrylate, methyl acrylate, ethyl acrylate, n-propyl acrylate, or the like, alone or in combination.

The at least one first graft link monomer may be an (acryloxy)alkoxysilane, a (mercaptoalkyl)alkoxysilane, a vinylalkoxysilane, or an allylalkoxysilane, alone or in combination, e.g., (gamma-methacryloxypropyl)(dimethoxy)methylsilane and/or (3-mercaptopropyl)trimethoxysilane. The at least one second graft link monomer is a polyethylenically unsaturated compound having at least one allyl group, such as allyl methacrylate, triallyl cyanurate, or triallyl isocyanurate, alone or in combination.

The silicone-acrylate impact modifier compositions can be prepared by emulsion polymerization, wherein, for example at least one silicone rubber monomer is reacted with at least one first graft link monomer at a temperature from about 30° C. to about 110° C. to form a silicone rubber latex, in the presence of a surfactant such as dodecylbenzenesulfonic acid. Alternatively, a cyclic siloxane such as cyclooctamethyltetrasiloxane and a tetraethoxyorthosilicate may be reacted with a first graft link monomer such as (gamma-methacryloxypropyl)methyldimethoxysilane, to afford silicone rubber having an average particle size from about 100 nanometers to about 2 micrometers. At least one branched acrylate rubber monomer is then polymerized with the silicone rubber particles, optionally in the presence of a cross linking monomer, such as allylmethacrylate in the presence of a free radical generating polymerization catalyst such as benzoyl peroxide. This latex is then reacted with a polymerizable alkenyl-containing organic material and a second graft link monomer. The latex particles of the graft silicone-acrylate rubber hybrid may be separated from the aqueous phase through coagulation (by treatment with a coagulant) and dried to a fine powder to produce the silicone-acrylate rubber impact modifier composition. This method can be generally used for producing the silicone-acrylate impact modifier having a particle size from about 100 nanometers to about two micrometers.

Processes known for the formation of the foregoing elastomer-modified graft copolymers include mass, emulsion, suspension, and solution processes, or combined processes such as bulk-suspension, emulsion-bulk, bulk-solution or other techniques, using continuous, semibatch, or batch processes.

If desired, the foregoing types of impact modifiers may be prepared by an emulsion polymerization process that is free of basic materials such as alkali metal salts of C_6-30fatty acids, for example sodium stearate, lithium stearate, sodium oleate, potassium oleate, and the like, alkali metal carbonates, amines such as dodecyl dimethyl amine, dodecyl amine, and the like, and ammonium salts of amines, or any other material, such as an acid, that contains a degradation catalyst. Such materials are commonly used as surfactants in emulsion polymerization, and may catalyze transesterification and/or degradation of polycarbonates. Instead, ionic sulfate, sulfonate or phosphate surfactants may be used in preparing the impact modifiers, particularly the elastomeric substrate portion of the impact modifiers. Suitable surfactants include, for example, C_1-22alkyl or C_7-25alkylaryl sulfonates, C_1-22alkyl or C_7-25alkylaryl sulfates, C_1-22alkyl or C_7-25alkylaryl phosphates, substituted silicates, and mixtures thereof. A specific surfactant is a C_6-16, specifically a C_8-12alkyl sulfonate. This emulsion polymerization process is described and disclosed in various patents and literature of such companies as Rohm & Haas and General Electric Company. In the practice, any of the above-described impact modifiers may be used providing it is free of the alkali metal salts of fatty acids, alkali metal carbonates and other basic materials.

A specific impact modifier of this type is a methyl methacrylate-butadiene-styrene (MBS) impact modifier wherein the butadiene substrate is prepared using above-described sulfonates, sulfates, or phosphates as surfactants. Other examples of elastomer-modified graft copolymers besides MBS include but are not limited to acrylonitrile-butadiene-styrene (ABS or bulk ABS), acrylonitrile-styrene-butyl acrylate (ASA), methyl methacrylate-acrylonitrile-butadiene-styrene (MABS), and acrylonitrile-ethylene-propylene-diene-styrene (AES).

In some embodiments, the impact modifier is a graft polymer having a high rubber content, i.e., greater than or equal to about 50 wt. %, optionally greater than or equal to about 60 wt. % by weight of the graft polymer. The rubber is preferably present in an amount less than or equal to about 95 wt. %, optionally less than or equal to about 90 wt. % of the graft polymer.

The rubber forms the backbone of the graft polymer, and is preferably a polymer of a conjugated diene having the formula (11):

wherein X^eis hydrogen, C₁-C₅alkyl, chlorine, or bromine. Examples of dienes that may be used are butadiene, isoprene, 1,3-hepta-diene, methyl-1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, 2-ethyl-1,3-pentadiene; 1,3- and 2,4-hexadienes, chloro and bromo substituted butadienes such as dichlorobutadiene, bromobutadiene, dibromobutadiene, mixtures comprising at least one of the foregoing dienes, and the like. A preferred conjugated diene is butadiene. Copolymers of conjugated dienes with other monomers may also be used, for example copolymers of butadiene-styrene, butadiene-acrylonitrile, and the like. Alternatively, the backbone may be an acrylate rubber, such as one based on n-butyl acrylate, ethylacrylate, 2-ethylhexylacrylate, mixtures comprising at least one of the foregoing, and the like. Additionally, minor amounts of a diene may be copolymerized in the acrylate rubber backbone to yield improved grafting.

After formation of the backbone polymer, a grafting monomer is polymerized in the presence of the backbone polymer. One preferred type of grafting monomer is a monovinylaromatic hydrocarbon having the formula (12):

wherein X^bis as defined above and X^fis hydrogen, C₁-C₁₀alkyl, C₁-C₁₀cycloalkyl, C₁-C₁₀alkoxy, C₆-C₁₈alkyl, C₆-C₁₈aralkyl, C₆-C₁₈aryloxy, chlorine, bromine, and the like. Examples include styrene, 3-methylstyrene, 3,5-diethylstyrene, 4-n-propylstyrene, alpha-methylstyrene, alpha-methyl vinyltoluene, alpha-chlorostyrene, alpha-bromostyrene, dichlorostyrene, dibromostyrene, tetra-chlorostyrene, mixtures comprising at least one of the foregoing compounds, and the like.

A second type of grafting monomer that may be polymerized in the presence of the polymer backbone are acrylic monomers of formula (13):

wherein X^bis as previously defined and Y²is cyano, C₁-C₁₂alkoxycarbonyl, or the like. Examples of such acrylic monomers include acrylonitrile, ethacrylonitrile, methacrylonitrile, alpha-chloroacrylonitrile, beta-chloroacrylonitrile, alpha-bromoacrylonitrile, beta-bromoacrylonitrile, methyl acrylate, methyl methacrylate, ethyl acrylate, butyl acrylate, propyl acrylate, isopropyl acrylate, mixtures comprising at least one of the foregoing monomers, and the like.

A mixture of grafting monomers may also be used, to provide a graft copolymer. An example of a suitable mixture comprises a monovinylaromatic hydrocarbon and an acrylic monomer. Examples of graft copolymers suitable for use include, but are not limited to, acrylonitrile-butadiene-styrene (ABS) and methacrylonitrile-butadiene-styrene (MBS) resins. Suitable high-rubber acrylonitrile-butadiene-styrene resins are available from General Electric Company as BLENDEX® grades 131, 336, 338, 360, and 415. Bulk ABS resins, having lower rubber content, are also suitable. Bulk ABS resins having about 17 wt. % polybutadiene are available from General Electric Company as well as Nippon A&L Co.

The composition may optionally comprise a polycarbonate-polysiloxane copolymer comprising polycarbonate blocks and polydiorganosiloxane blocks. The polycarbonate blocks in the copolymer comprise repeating structural units of formula (1) as described above, for example wherein R¹is of formula (2) as described above. These units may be derived from reaction of dihydroxy compounds of formula (3) as described above. In one embodiment, the dihydroxy compound is bisphenol A, in which each of A¹and A²is p-phenylene and Y¹is isopropylidene.

The polydiorganosiloxane blocks comprise repeating structural units of formula (14) (sometimes referred to herein as ‘siloxane’):

wherein each occurrence of R is same or different, and is a C_1-13monovalent organic radical. For example, R may be a C₁-C₁₃alkyl group, C₁-C₁₃alkoxy group, C₂-C₁₃alkenyl group, C₂-C₁₃alkenyloxy group, C₃-C₆cycloalkyl group, C₃-C₆cycloalkoxy group, C₆-C₁₀aryl group, C₆-C₁₀aryloxy group, C₇-C₁₃aralkyl group, C₇-C₁₃aralkoxy group, C₇-C₁₃alkaryl group, or C₇-C₁₃alkaryloxy group. Combinations of the foregoing R groups may be used in the same copolymer.

The value of D in formula (14) may vary widely depending on the type and relative amount of each component in the thermoplastic composition, the desired properties of the composition, and like considerations. Generally, D may have an average value of 2 to about 1000, specifically about 2 to about 500, more specifically about 5 to about 100. In one embodiment, D has an average value of about 10 to about 75, and in still another embodiment, D has an average value of about 20 to about 60. Where D is of a lower value, e.g., less than about 40, it may be desirable to use a relatively larger amount of the polycarbonate-polysiloxane copolymer. Conversely, where D is of a higher value, e.g., greater than about 40, it may be necessary to use a relatively lower amount of the polycarbonate-polysiloxane copolymer.

A combination of a first and a second (or more) polycarbonate-polysiloxane copolymers may be used, wherein the average value of D of the first copolymer is less than the average value of D of the second copolymer.

In one embodiment, the polydiorganosiloxane blocks are provided by repeating structural units of formula (15):

wherein D is as defined above; each R may be the same or different, and is as defined above; and Ar may be the same or different, and is a substituted or unsubstituted C₆-C₃₀arylene radical, wherein the bonds are directly connected to an aromatic moiety. Suitable Ar groups in formula (15) may be derived from a C₆-C₃₀dihydroxyarylene compound, for example a dihydroxyarylene compound of formula (3), (4), or (7) above. Combinations comprising at least one of the foregoing dihydroxyarylene compounds may also be used. Specific examples of suitable dihydroxyarlyene compounds are 1,1-bis(4-hydroxyphenyl)methane, 1,1-bis(4-hydroxyphenyl)ethane, 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(4-hydroxyphenyl)butane, 2,2-bis(4-hydroxyphenyl)octane, 1,1-bis(4-hydroxyphenyl)propane, 1,1-bis(4-hydroxyphenyl)n-butane, 2,2-bis(4-hydroxy-1-methylphenyl)propane, 1,1-bis(4-hydroxyphenyl)cyclohexane, bis(4-hydroxyphenyl sulphide), and 1,1-bis(4-hydroxy-t-butylphenyl)propane. Combinations comprising at least one of the foregoing dihydroxy compounds may also be used.

Such units may be derived from the corresponding dihydroxy compound of the following formula (16):

wherein Ar and D are as described above. Such compounds are further described in U.S. Pat. No. 4,746,701 to Kress et al. Compounds of this formula may be obtained by the reaction of a dihydroxyarylene compound with, for example, an alpha, omega-bisacetoxypolydiorangonosiloxane under phase transfer conditions.

In another embodiment the polydiorganosiloxane blocks comprise repeating structural units of formula (17):

wherein R and D are as defined above. R²in formula (17) is a divalent C₂-C₈aliphatic group. Each M in formula (17) may be the same or different, and may be a halogen, cyano, nitro, C₁-C₈alkylthio, C₁-C₈alkyl, C₁-C₈alkoxy, C₂-C₈alkenyl, C₂-C₈alkenyloxy group, C₃-C₈cycloalkyl, C₃-C₈cycloalkoxy, C₆-C₁₀aryl, C₆-C₁₀aryloxy, C₇-C₁₂aralkyl, C₇-C₁₂aralkoxy, C₇-C₁₂alkaryl, or C₇-C₁₂alkaryloxy, wherein each n is independently 0, 1, 2, 3, or 4.

In one embodiment, M is bromo or chloro, an alkyl group such as methyl, ethyl, or propyl, an alkoxy group such as methoxy, ethoxy, or propoxy, or an aryl group such as phenyl, chlorophenyl, or tolyl; R²is a dimethylene, trimethylene or tetramethylene group; and R is a C_1-8alkyl, haloalkyl such as trifluoropropyl, cyanoalkyl, or aryl such as phenyl, chlorophenyl or tolyl. In another embodiment, R is methyl, or a mixture of methyl and trifluoropropyl, or a mixture of methyl and phenyl. In still another embodiment, M is methoxy, n is one, R²is a divalent C₁-C₃aliphatic group, and R is methyl.

These units may be derived from the corresponding dihydroxy polydiorganosiloxane (18):

wherein R, D, M, R², and n are as described above.

Such dihydroxy polysiloxanes can be made by effecting a platinum catalyzed addition between a siloxane hydride of the formula (19),

wherein R and D are as previously defined, and an aliphatically unsaturated monohydric phenol. Suitable aliphatically unsaturated monohydric phenols included, for example, eugenol, 2-alkylphenol, 4-allyl-2-methylphenol, 4-allyl-2-phenylphenol, 4-allyl-2-bromophenol, 4-allyl-2-t-butoxyphenol, 4-phenyl-2-phenylphenol, 2-methyl-4-propylphenol, 2-allyl-4,6-dimethylphenol, 2-allyl-4-bromo-6-methylphenol, 2-allyl-6-methoxy-4-methylphenol and 2-allyl-4,6-dimethylphenol. Mixtures comprising at least one of the foregoing may also be used.

The polycarbonate-polysiloxane copolymer may be manufactured by reaction of diphenolic polysiloxane (18) with a carbonate source and a dihydroxy aromatic compound of formula (3), optionally in the presence of a phase transfer catalyst as described above. Suitable conditions are similar to those useful in forming polycarbonates. For example, the copolymers are prepared by phosgenation, at temperatures from below 0° C. to about 100° C., preferably about 25° C. to about 50° C. Since the reaction is exothermic, the rate of phosgene addition may be used to control the reaction temperature. The amount of phosgene required will generally depend upon the amount of the dihydric reactants. Alternatively, the polycarbonate-polysiloxane copolymers may be prepared by co-reacting in a molten state, the dihydroxy monomers and a diaryl carbonate ester, such as diphenyl carbonate, in the presence of a transesterification catalyst as described above.

In the production of the polycarbonate-polysiloxane copolymer, the amount of dihydroxy polydiorganosiloxane is selected so as to provide the desired amount of polydiorganosiloxane units in the copolymer. The amount of polydiorganosiloxane units may vary widely, i.e., may be about 1 wt. % to about 99 wt. % of polydimethylsiloxane, or an equivalent molar amount of another polydiorganosiloxane, with the balance being carbonate units. The particular amounts used will therefore be determined depending on desired physical properties of the thermoplastic composition, the value of D (within the range of 2 to about 1000), and the type and relative amount of each component in the thermoplastic composition, including the type and amount of polycarbonate, type and amount of impact modifier, type and amount of polycarbonate-polysiloxane copolymer, and type and amount of any other additives. Suitable amounts of dihydroxy polydiorganosiloxane can be determined by one of ordinary skill in the art without undue experimentation using the guidelines taught herein. For example, the amount of dihydroxy polydiorganosiloxane may be selected so as to produce a copolymer comprising about 1 wt. % to about 75 wt. %, or about 1 wt. % to about 50 wt. % polydimethylsiloxane, or an equivalent molar amount of another polydiorganosiloxane. In one embodiment, the copolymer comprises about 5 wt. % to about 40 wt. %, optionally about 5 wt. % to about 25 wt. % polydimethylsiloxane, or an equivalentmolar amount of another polydiorganosiloxane, with the balance being polycarbonate. In a particular embodiment, the copolymer may comprise about 20 wt. % siloxane.

The composition optionally comprises an ungrafted rigid copolymer. In one embodiment, the ungrafted rigid copolymer comprises acrylonitrile monomer. The rigid copolymer is additional to any rigid copolymer present in the impact modifier. It may be the same as any of the rigid copolymers described above, without the elastomer modification. The rigid copolymers generally have a Tg greater than about 15° C., specifically greater than about 20° C., and include, for example, polymers derived from monovinylaromatic monomers containing condensed aromatic ring structures, such as vinyl naphthalene, vinyl anthracene and the like, or monomers of formula (9) as broadly described above, for example styrene and alpha-methyl styrene; monovinylic monomers such as itaconic acid, acrylamide, N-substituted acrylamide or methacrylamide, maleic anhydride, maleimide, N-alkyl, aryl or haloaryl substituted maleimide, glycidyl(meth)acrylates, and monomers of the general formula (10) as broadly described above, for example acrylonitrile, methyl acrylate and methyl methacrylate; and copolymers of the foregoing, for example styrene-acrylonitrile (SAN), styrene-alpha-methyl styrene-acrylonitrile, methyl methacrylate-acrylonitrile-styrene, and methyl methacrylate-styrene.

The rigid copolymer may comprise about 1 to about 99 wt. %, specifically about 20 to about 95 wt. %, more specifically about 40 to about 90 wt. % of vinylaromatic monomer, together with 1 to about 99 wt. %, specifically about 5 to about 80 wt. %, more specifically about 10 to about 60 wt. % of copolymerizable monovinylic monomers. In one embodiment the rigid copolymer is SAN, which may comprise about 50 to about 99 wt. % styrene, with the balance acrylonitrile, specifically about 60 to about 90 wt. % styrene, and more specifically about 65 to about 85 wt. % styrene, with the remainder acrylonitrile.

In another embodiment, the ungrafted rigid copolymer comprises a (meth)acrylate monomer. The rigid copolymers include, for example, a poly(alkyl (meth)acrylate), wherein the alkyl group is straight or branched-chain, and has 1 or 2 carbons atoms. In one embodiment the rigid copolymer is a poly(alkyl(meth)acrylate), specifically a poly(methyl methacrylate) (PMMA). PMMA may be produced by the polymerization of methyl methacrylate monomer, and may be derived by (1) the reaction of acetone cyanohydrin, methanol, and sulphuric acid or (2) the oxidation of tert-butyl alcohol to methacrolein and then to methacrylic acid followed by the esterification reaction with methanol. As is known, PMMA homopolymer is difficult to obtain, and therefore is available commercially and used herein as a mixture of the homopolymer and various copolymers of methyl methacrylate and C₁-C₄alkyl acrylates, such as ethyl acrylate. “PMMA” as used herein therefore includes such mixtures, which are commercially available from, for example, Atofina under the trade designations V825, V826, V920, V045, and VM, and from Lucite under the trade names CLG340, CLG356, CLG960, CLG902, CMG302.

Blends comprising more than one ungrafted rigid copolymer may also be used, if desired.

The rigid copolymer may be manufactured by bulk, suspension, or emulsion polymerization. In one embodiment, the rigid copolymer is manufactured by bulk polymerization using a boiling reactor. The rigid copolymer may have a weight average molecular weight of about 50,000 to about 300,000 as measured by GPC using polystyrene standards. In one embodiment, the weight averagemolecular weight of the rigid copolymer is about 50,000 to about 200,000.

The thermoplastic composition further comprises an anti-static additive. The anti-static additive comprises a halogenated carbon sulfonic acid salt of a polysubstituted phosphonium compound. The substituted phosphonium salts of the medium and short chain sulfonic acids have the general formula (20):

wherein X is independently selected from halogen or hydrogen provided that at least one X is halogen; n, m and p are integers from 0 to 12; and Y is zero or a heterocyclic atom, other than carbon, of an atomic ring and is either nitrogen, oxygen, sulfur, selenium, phosphorus, arsenic, and the like; R₁, R₂, and R₃are the same, each having an aliphatic hydrocarbon radical with 1 to 8 carbon atoms or an aromatic hydrocarbon radical of 6 to 12 carbon atoms and R₄is a hydrocarbon radical with 1 to 18 carbon atoms. The halogens may be independently selected from bromine, chlorine, fluorine and iodine. In one embodiment, the halogen is fluorine.

In one embodiment, the phosphonium sulfonate is fluorinated phosphonium sulfonate and is composed of a fluorocarbon containing an organic sulfonate anion and an organic phosphonium cation. Examples of such organic sulfonate anions include perfluoro methane sulfonate, perfluoro butane sulfonate, perfluoro hexane sulfonate, perfluoro heptane sulfonate and perfluoro octane sulfonate. Examples of the aforementioned phosphonium cation include aliphatic phosphonium such as tetramethyl phosphonium, tetraethyl phosphonium, tetrabutyl phosphonium, triethylmethyl phosphonium, tributylmethyl phosphonium, tributylethyl phosphonium, trioctylmethyl phosphonium, trimethylbutyl phosphonium trimethyloctyl phosphonium, trimethyllauryl phosphonium, trimethylstearyl phosphonium, triethyloctyl phosphonium and aromatic phosphoniums such as tetraphenyl phosphonium, triphenylmethyl phosphonium, triphenylbenzyl phosphonium, tributylbenzyl phosphonium.

The fluorinated phosphonium sulfonate of the present invention can be obtained by any combination of any of these organic sulfonate anions and organic cations but this invention is not limited by the examples given above. Fluorinated phosphonium sulfonate may be produced in a very pure form by mixing the corresponding sulfonic acid and the quaternary phosphonium hydroxide in a solvent mixture followed by evaporation of the solvent mixture. Tetrabutyl phosphonium perfluoro butane sulfonate, for example, can be produced with a yield of about 95% by placing 98.6 g. of perfluoro butane sulfonic acid, 200 ml. of a 40 wt. % solution of tetrabutyl phosphonium hydroxide and a 500 ml of a solvent mixture in a flask, stirring the mixture for one hour at room temperature, isolating phosphonium sulfonate which separates as an oily layer, washing it with 100 ml of water, followed by evaporation of the solvents using a vacuum pump.

As previously stated, in one embodiment the phosphonium sulfonate is a fluorinated phosphonium sulfonate having the general formula (21):

wherein F is fluorine; n is an integer of from 1 to 12, S is sulfur; R₁, R₂and R₃are the same, each having an aliphatic hydrocarbon radical of 1 to 8 carbon atoms or an aromatic hydrocarbon radical of 6 to 12 carbon atoms and R₄is a hydrocarbon radical of 1 to 18 carbon atoms.

The anti-static additive is generally present in an amount of from 0.5 to about 12.5 mol, based on 100 kg of the thermoplastic composition, optionally from 0.9 to 5.38 mol per 100 kg of the thermoplastic composition. When tetrabutylphosphonium perfluorobutylsulfonate (“FC-1”) is used as the anti-static additive, it is generally present in an amount of less than 7 wt. %, generally from 0.5 to less than 5 wt. %.

The thermoplastic composition further comprises a flame retardant additive. Suitable flame retardants that may be added may be organic compounds that include phosphorus, bromine, and/or chlorine. Non-brominated and non-chlorinated phosphorus-containing flame retardants may be preferred in certain applications for regulatory reasons, for example organic phosphates and organic compounds containing phosphorus-nitrogen bonds.

One type of exemplary organic phosphate is an aromatic phosphate of the formula (GO)₃P═O, wherein each G is independently an alkyl, cycloalkyl, aryl, alkaryl, or aralkyl group, provided that at least one G is an aromatic group. Two of the G groups may be joined together to provide a cyclic group, for example, diphenyl pentaerythritol diphosphate, which is described by Axelrod in U.S. Pat. No. 4,154,775. Other suitable aromatic phosphates may be, for example, phenyl bis(dodecyl)phosphate, phenyl bis(neopentyl)phosphate, phenyl bis(3,5,5′-trimethylhexyl)phosphate, ethyl diphenyl phosphate, 2-ethylhexyl di(p-tolyl)phosphate, bis(2-ethylhexyl)p-tolyl phosphate, tritolyl phosphate, bis(2-ethylhexyl)phenyl phosphate, tri(nonylphenyl)phosphate, bis(dodecyl)p-tolyl phosphate, dibutyl phenyl phosphate, 2-chloroethyl diphenyl phosphate, p-tolyl bis(2,5,5′-trimethylhexyl)phosphate, 2-ethylhexyl diphenyl phosphate, or the like. A specific aromatic phosphate is one in which each G is aromatic, for example, triphenyl phosphate, tricresyl phosphate, isopropylated triphenyl phosphate, and the like.

Di- or polyfunctional aromatic phosphorus-containing compounds are also useful, for example, compounds of the formulas below:

wherein each G¹is independently a hydrocarbon having 1 to about 30 carbon atoms; each G²is independently a hydrocarbon or hydrocarbonoxy having 1 to about 30 carbon atoms; each X^ais as defined above; each X is independently a bromine or chlorine; m is 0 to 4, and n is 1 to about 30. Examples of suitable di- or polyfunctional aromatic phosphorus-containing compounds include resorcinol tetraphenyl diphosphate (RDP), the bis(diphenyl)phosphate of hydroquinone and the bis(diphenyl)phosphate of bisphenol-A, respectively, their oligomeric and polymeric counterparts, and the like.

Exemplary suitable flame retardant compounds containing phosphorus-nitrogen bonds include phosphonitrilic chloride, phosphorus ester amides, phosphoric acid amides, phosphonic acid amides, phosphinic acid amides, tris(aziridinyl)phosphine oxide.

Some formulations are required to meet certain environmental or ECO standards, and certain materials, such as halogens, cannot be present, or can only be present in extremely low levels. If halogens are not a concern in the composition, halogenated materials may also be used as flame retardants, for example halogenated compounds and resins of formula (22):

wherein R is an alkylene, alkylidene or cycloaliphatic linkage, e.g., methylene, ethylene, propylene, isopropylene, isopropylidene, butylene, isobutylene, amylene, cyclohexylene, cyclopentylidene, or the like; or an oxygen ether, carbonyl, amine, or a sulfur containing linkage, e.g., sulfide, sulfoxide, sulfone, or the like. R can also consist of two or more alkylene or alkylidene linkages connected by such groups as aromatic, amino, ether, carbonyl, sulfide, sulfoxide, sulfone, or the like.

Ar and Ar′ in formula (22) are each independently mono- or polycarbocyclic aromatic groups such as phenylene, biphenylene, terphenylene, naphthylene, or the like.

Y is an organic, inorganic, or organometallic radical, for example (1) halogen, e.g., chlorine, bromine, iodine, fluorine or (2) ether groups of the general formula OE, wherein E is a monovalent hydrocarbon radical similar to X or (3) monovalent hydrocarbon groups of the type represented by R or (4) other substituents, e.g., nitro, cyano, and the like, said substituents being essentially inert provided that there is at least one and optionally two halogen atoms per aryl nucleus.

When present, each X is independently a monovalent hydrocarbon group, for example an alkyl group such as methyl, ethyl, propyl, isopropyl, butyl, decyl, or the like; an aryl groups such as phenyl, naphthyl, biphenyl, xylyl, tolyl, or the like; and aralkyl group such as benzyl, ethylphenyl, or the like; a cycloaliphatic group such as cyclopentyl, cyclohexyl, or the like. The monovalent hydrocarbon group may itself contain inert substituents.

Each d is independently 1 to a maximum equivalent to the number of replaceable hydrogens substituted on the aromatic rings comprising Ar or Ar′. Each e is independently 0 to a maximum equivalent to the number of replaceable hydrogens on R. Each a, b, and c is independently a whole number, including 0. When b is not 0, neither a nor c may be 0. Otherwise either a or c, but not both, may be 0. Where b is 0, the aromatic groups are joined by a direct carbon-carbon bond.

The hydroxyl and Y substituents on the aromatic groups, Ar and Ar′ can be varied in the ortho, meta or para positions on the aromatic rings and the groups can be in any possible geometric relationship with respect to one another.

Included within the scope of the above formula are bisphenols of which the following are representative: 2,2-bis-(3,5-dichlorophenyl)-propane; bis-(2-chlorophenyl)-methane; bis(2,6-dibromophenyl)-methane; 1,1-bis-(4-iodophenyl)-ethane; 1,2-bis-(2,6-dichlorophenyl)-ethane; 1,1-bis-(2-chloro-4-iodophenyl)ethane; 1,1-bis-(2-chloro-4-methylphenyl)-ethane; 1,1-bis-(3,5-dichlorophenyl)-ethane; 2,2-bis-(3-phenyl-4-bromophenyl)-ethane; 2,6-bis-(4,6-dichloronaphthyl)-propane; 2,2-bis-(2,6-dichlorophenyl)-pentane; 2,2-bis-(3,5-dibromophenyl)-hexane; bis-(4-chlorophenyl)-phenyl-methane; bis-(3,5-dichlorophenyl)-cyclohexylmethane; bis-(3-nitro-4-bromophenyl)-methane; bis-(4-hydroxy-2,6-dichloro-3-methoxyphenyl)-methane; and 2,2-bis-(3,5-dichloro-4-hydroxyphenyl)-propane 2,2-bis-(3-bromo-4-hydroxyphenyl)-propane. Also included within the above structural formula are: 1,3-dichlorobenzene, 1,4-dibromobenzene, 1,3-dichloro-4-hydroxybenzene, and biphenyls such as 2,2′-dichlorobiphenyl, polybrominated 1,4-diphenoxybenzene, 2,4′-dibromobiphenyl, and 2,4′-dichlorobiphenyl as well as decabromo diphenyl oxide, and the like.

Also useful are oligomeric and polymeric halogenated aromatic compounds, such as a copolycarbonate of bisphenol A and tetrabromobisphenol A and a carbonate precursor, e.g., phosgene. Metal synergists, e.g., antimony oxide, may also be used with the flame retardant.

Inorganic flame retardants may also be used, for example salts of C_1-16alkyl sulfonate salts such as potassium perfluorobutane sulfonate (Rimar salt), potassium perfluoroctane sulfonate, tetraethylammonium perfluorohexane sulfonate, and potassium diphenylsulfone sulfonate, and the like; salts formed by reacting for example an alkali metal or alkaline earth metal (for example lithium, sodium, potassium, magnesium, calcium and barium salts) and an inorganic acid complex salt, for example, an oxo-anion, such as alkali metal and alkaline-earth metal salts of carbonic acid, such as Na₂CO₃, K₂CO₃, MgCO₃, CaCO₃, and BaCO₃or a fluoro-anion complex such as Li₃AlF₆, BaSiF₆, KBF₄, K₃AlF₆, KAlF₄, K₂SiF₆, and/or Na₃AlF₆or the like.

The relative amount of each component of the thermoplastic composition will depend on the particular type of polycarbonate(s) used, the presence of any other resins, and the particular impact modifier(s), the flame retardant additive, and anti-static additive, and any optional components, as well as the desired properties of the composition. Particular amounts may be readily selected by one of ordinary skill in the art using the guidance provided herein.

In one embodiment, the thermoplastic composition comprises about 50 to about 98 wt. % polycarbonate, about 1 to about 30 wt. % impact modifier, and about 1 to about 20 flame retardant additive, and about 0.9 to about 5.38 mol of anti-static additive, wherein the amount of anti-static additive is based on 100 kg of the thermoplastic composition. The thermoplastic composition optionally comprises an anti-drip agent and/or a polycarbonate-polysiloxane copolymer.

In addition, the thermoplastic composition may include various additives such as fillers, reinforcing agents, stabilizers, and the like, with the proviso that the additives do not adversely affect the desired properties of the thermoplastic compositions.

Examples of suitable fillers or reinforcing agents include any materials known for these uses. For example, suitable fillers and reinforcing agents include silicates and silica powders such as aluminum silicate (mullite), synthetic calcium silicate, zirconium silicate, fused silica, crystalline silica graphite, natural silica sand, or the like; boron powders such as boron-nitride powder, boron-silicate powders, or the like; oxides such as TiO₂, aluminum oxide, magnesium oxide, or the like; calcium sulfate (as its anhydride, dihydrate or trihydrate); calcium carbonates such as chalk, limestone, marble, synthetic precipitated calcium carbonates, or the like; talc, including fibrous, modular, needle shaped, lamellar talc, or the like; wollastonite; surface-treated wollastonite; glass spheres such as hollow and solid glass spheres, silicate spheres, cenospheres, aluminosilicate (atmospheres), or the like; kaolin, including hard kaolin, soft kaolin, calcined kaolin, kaolin comprising various coatings known in the art to facilitate compatibility with the polymeric matrix resin, or the like; single crystal fibers or “whiskers” such as silicon carbide, alumina, boron carbide, iron, nickel, copper, or the like; fibers (including continuous and chopped fibers) such as asbestos, carbon fibers, glass fibers, such as E, A, C, ECR, R, S, D, or NE glasses, or the like; sulfides such as molybdenum sulfide, zinc sulfide or the like; barium compounds such as barium titanate, barium ferrite, barium sulfate, heavy spar, or the like; metals and metal oxides such as particulate or fibrous aluminum, bronze, zinc, copper and nickel or the like; flaked fillers such as glass flakes, flaked silicon carbide, aluminum diboride, aluminum flakes, steel flakes or the like; fibrous fillers, for example short inorganic fibers such as those derived from blends comprising at least one of aluminum silicates, aluminum oxides, magnesium oxides, and calcium sulfate hemihydrate or the like; natural fillers and reinforcements, such as wood flour obtained by pulverizing wood, fibrous products such as cellulose, cotton, sisal, jute, starch, cork flour, lignin, ground nut shells, corn, rice grain husks or the like; organic fillers such as polytetrafluoroethylene; reinforcing organic fibrous fillers formed from organic polymers capable of forming fibers such as poly(ether ketone), polyimide, polybenzoxazole, poly(phenylene sulfide), polyesters, polyethylene, aromatic polyamides, aromatic polyimides, polyetherimides, polytetrafluoroethylene, acrylic resins, poly(vinyl alcohol) or the like; as well as additional fillers and reinforcing agents such as mica, clay, feldspar, flue dust, fillite, quartz, quartzite, perlite, tripoli, diatomaceous earth, carbon black, or the like, or combinations comprising at least one of the foregoing fillers or reinforcing agents.

The fillers and reinforcing agents may be coated with a layer of metallic material to facilitate conductivity, or surface treated with silanes to improve adhesion and dispersion with the polymeric matrix resin. In addition, the reinforcing fillers may be provided in the form of monofilament or multifilament fibers and may be used either alone or in combination with other types of fiber, through, for example, co-weaving or core/sheath, side-by-side, orange-type or matrix and fibril constructions, or by other methods known to one skilled in the art of fiber manufacture. Suitable cowoven structures include, for example, glass fiber-carbon fiber, carbon fiber-aromatic polyimide (aramid) fiber, and aromatic polyimide fiberglass fiber or the like. Fibrous fillers may be supplied in the form of, for example, rovings, woven fibrous reinforcements, such as 0-90 degree fabrics or the like; non-woven fibrous reinforcements such as continuous strand mat, chopped strand mat, tissues, papers and felts or the like; or three-dimensional reinforcements such as braids. Fillers are generally used in amounts of about zero to about 50 parts by weight, optionally about 1 to about 20 parts by weight, and in some embodiments, about 4 to about 15 parts by weight, based on 100 parts by weight of the thermoplastic composition.

In addition, the thermoplastic composition may include various additives ordinarily incorporated in resin compositions of this type, with the proviso that the additives are preferably selected so as to not significantly adversely affect the desired properties of the thermoplastic composition. Mixtures of additives may be used. Such additives may be mixed at a suitable time during the mixing of the components for forming the composition.

The compositions described herein may comprise a primary antioxidant or “stabilizer” (e.g., a hindered phenol and/or secondary aryl amine) and, optionally, a secondary antioxidant (e.g., a phosphate and/or thioester). Suitable antioxidant additives include, for example, organophosphites such as tris(nonyl phenyl)phosphite, tris(2,4-di-t-butylphenyl)phosphite, bis(2,4-di-t-butylphenyl)pentaerythritol diphosphite, distearyl pentaerythritol diphosphite or the like; alkylated monophenols or polyphenols; alkylated reaction products of polyphenols with dienes, such as tetrakis[methylene(3,5-di-tert-butyl-4-hydroxyhydrocinnamate)]methane, or the like; butylated reaction products of para-cresol or dicyclopentadiene; alkylated hydroquinones; hydroxylated thiodiphenyl ethers; alkylidene-bisphenols; benzyl compounds; esters of beta-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionic acid with monohydric or polyhydric alcohols; esters of beta-(5-tert-butyl-4-hydroxy-3-methylphenyl)-propionic acid with monohydric or polyhydric alcohols; esters of thioalkyl or thioaryl compounds such as distearylthiopropionate, dilaurylthiopropionate, ditridecylthiodipropionate, octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, pentaerythrityl-tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate or the like; amides of beta-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionic acid or the like, or combinations comprising at least one of the foregoing antioxidants. Antioxidants are generally used in amounts of about 0.01 to about 1 parts by weight, optionally about 0.05 to about 0.5 parts by weight, based on 100 parts by weight of the thermoplastic composition.

Suitable heat stabilizer additives include, for example, organophosphites such as triphenyl phosphite, tris-(2,6-dimethylphenyl)phosphite, tris-(mixed mono-and di-nonylphenyl)phosphite or the like; phosphonates such as dimethylbenzene phosphonate or the like, phosphates such as trimethyl phosphate, or the like, or combinations comprising at least one of the foregoing heat stabilizers. Heat stabilizers are generally used in amounts of about 0.01 to about 5 parts by weight, optionally about 0.05 to about 0.3 parts by weight, based on 100 parts by weight of the thermoplastic composition.

Light stabilizers and/or ultraviolet light (UV) absorbing additives may also be used. Suitable light stabilizer additives include, for example, benzotriazoles such as 2-(2-hydroxy-5-methylphenyl)benzotriazole, 2-(2-hydroxy-5-tert-octylphenyl)-benzotriazole and 2-hydroxy-4-n-octoxy benzophenone, or the like, or combinations comprising at least one of the foregoing light stabilizers. Light stabilizers are generally used in amounts of about 0.01 to about 10 parts by weight, optionally about 0.1 to about 1 parts by weight, based on 100 parts by weight of the thermoplastic composition.

Suitable UV absorbing additives include for example, hydroxybenzophenones; hydroxybenzotriazoles; hydroxybenzotriazines; cyanoacrylates; oxanilides; benzoxazinones; 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)-phenol (CYASORB™ 5411); 2-hydroxy-4-n-octyloxybenzophenone (CYASORB™ 531); 2-[4,6-bis(2,4-dimethylphenyl)-1,3,5-triazin-2-yl]-5-(octyloxy)-phenol (CYASORB™ 1164); 2,2′-(1,4-phenylene)bis(4H-3,1-benzoxazin-4-one) (CYASORB™ UV-3638); 1,3-bis[(2-cyano-3,3-diphenylacryloyl)oxy]-2,2-bis[[(2-cyano-3,3-diphenylacryloyl)oxy]methyl]propane (UVINUL™ 3030); 2,2′-(1,4-phenylene)bis(4H-3,1-benzoxazin-4-one); 1,3-bis[(2-cyano-3,3-diphenylacryloyl)oxy]-2,2-bis[[(2-cyano-3,3-diphenylacryloyl)oxy]methyl]propane; nano-size inorganic materials such as titanium oxide, cerium oxide, and zinc oxide, all with particle size less than about 100 nanometers; or the like, or combinations comprising at least one of the foregoing UV absorbers. UV absorbers are generally used in amounts of about 0.1 to about 5 parts by weight, based on 100 parts by weight of the thermoplastic composition.

Plasticizers, lubricants, and/or mold release agents additives may also be used. There is considerable overlap among these types of materials, which include, for example, phthalic acid esters such as dioctyl-4,5-epoxy-hexahydrophthalate; tris-(octoxycarbonylethyl)isocyanurate; tristearin; di- or polyfunctional aromatic phosphates such as resorcinol tetraphenyl diphosphate (RDP), the bis(diphenyl)phosphate of hydroquinone and the bis(diphenyl)phosphate of bisphenol-A; poly-alpha-olefins; epoxidized soybean oil; silicones, including silicone oils; esters, for example, fatty acid esters such as alkyl stearyl esters, e.g., methyl stearate; stearyl stearate, pentaerythritol tetrastearate, and the like; mixtures of methyl stearate and hydrophilic and hydrophobic nonionic surfactants comprising polyethylene glycol polymers, polypropylene glycol polymers, and copolymers thereof, e.g., methyl stearate and polyethylene-polypropylene glycol copolymers in a suitable solvent; waxes such as beeswax, montan wax, paraffin wax or the like. Such materials are generally used in amounts of about 0.1 to about 20 parts by weight, optionally about 1 to about 10 parts by weight, based on 100 parts by weight of the thermoplastic composition.

Other antistatic agents may also be included in the thermoplastic composition if desired. Other examples of antistatic agents include monomeric, oligomeric, or polymeric materials that can be processed into polymer resins and/or sprayed onto materials or articles to improve conductive properties and overall physical performance. Examples of monomeric antistatic agents include glycerol monostearate, glycerol distearate, glycerol tristearate, ethoxylated amines, primary, secondary and tertiary amines, ethoxylated alcohols, alkyl sulfates, alkylarylsulfates, alkylphosphates, alkylaminesulfates, alkyl sulfonate salts such as sodium stearyl sulfonate, sodium dodecylbenzenesulfonate or the like, quaternary ammonium salts, quaternary ammonium resins, imidazoline derivatives, sorbitan esters, ethanolamides, betaines, or the like, or combinations comprising at least one of the foregoing monomeric antistatic agents.

Exemplary polymeric antistatic agents include certain polyesteramides, polyether-polyamide(polyetheramide) block copolymers, polyetheresteramide block copolymers, polyetheresters, or polyurethanes, each containing polyalkylene glycol moieties such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and the like. Such polymeric antistatic agents are commercially available, such as, for example, Pelestat™ 6321 (Sanyo), Pebax™ MH1657 (Atofina), and Irgastat™ P18 and P22 (Ciba-Geigy). Other polymeric materials that may be used as antistatic agents are inherently conducting polymers such as polyaniline (commercially available as PANIPOL®EB from Panipol), polypyrrole and polythiophene (commercially available from Bayer), which retain some of their intrinsic conductivity after melt processing at elevated temperatures. In one embodiment, carbon fibers, carbon nanofibers, carbon nanotubes, carbon black, or any combination of the foregoing may be used in a polymeric resin containing chemical antistatic agents to render the composition electrostatically dissipative. Antistatic agents are generally used in amounts of about 0.1 to about 10 parts by weight, based on 100 parts by weight of the thermoplastic composition.

Colorants such as pigment and/or dye additives may also be present. Suitable pigments include for example, inorganic pigments such as metal oxides and mixed metal oxides such as zinc oxide, titanium dioxides, iron oxides or the like; sulfides such as zinc sulfides, or the like; aluminates; sodium sulfo-silicates sulfates, chromates, or the like; carbon blacks; zinc ferrites; ultramarine blue; Pigment Brown 24; Pigment Red 101; Pigment Yellow 119; organic pigments such as azos, di-azos, quinacridones, perylenes, naphthalene tetracarboxylic acids, flavanthrones, isoindolinones, tetrachloroisoindolinones, anthraquinones, anthanthrones, dioxazines, phthalocyanines, and azo lakes; Pigment Blue 60, Pigment Red 122, Pigment Red 149, Pigment Red 177, Pigment Red 179, Pigment Red 202, Pigment Violet 29, Pigment Blue 15, Pigment Green 7, Pigment Yellow 147 and Pigment Yellow 150, or combinations comprising at least one of the foregoing pigments. Pigments are generally used in amounts of about 0.01 to about 10 parts by weight, based on 100 parts by weight of the thermoplastic composition.

Suitable dyes are generally organic materials and include, for example, coumarin dyes such as coumarin 460 (blue), coumarin 6 (green), nile red or the like; lanthanide complexes; hydrocarbon and substituted hydrocarbon dyes; polycyclic aromatic hydrocarbon dyes; scintillation dyes such as oxazole or oxadiazole dyes; aryl- or heteroaryl-substituted poly (C_2-8) olefin dyes; carbocyanine dyes; indanthrone dyes; phthalocyanine dyes; oxazine dyes; carbostyryl dyes; napthalenetetracarboxylic acid dyes; porphyrin dyes; bis(styryl)biphenyl dyes; acridine dyes; anthraquinone dyes; cyanine dyes; methine dyes; arylmethane dyes; azo dyes; indigoid dyes, thioindigoid dyes, diazonium dyes; nitro dyes; quinone imine dyes; aminoketone dyes; tetrazolium dyes; thiazole dyes; perylene dyes, perinone dyes; bis-benzoxazolylthiophene (BBOT); triarylmethane dyes; xanthene dyes; thioxanthene dyes; naphthalimide dyes; lactone dyes; fluorophores such as anti- stokes shift dyes which absorb in the near infrared wavelength and emit in the visible wavelength, or the like; luminescent dyes such as 7-amino-4-methylcoumarin; 3-(2′-benzothiazolyl)-7-diethylaminocoumarin; 2-(4-biphenylyl)-5-(4-t-butylphenyl)-1,3,4-oxadiazole; 2,5-bis-(4-biphenylyl)-oxazole; 2,2′-dimethyl-p-quaterphenyl; 2,2-dimethyl-p-terphenyl; 3,5,3″″,5″″-tetra-t-butyl-p-quinquephenyl; 2,5-diphenylfuran; 2,5-diphenyloxazole; 4,4′-diphenylstilbene; 4-dicyanomethylene-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran; 1,1′-diethyl-2,2′-carbocyanine iodide; 3,3′-diethyl-4,4′,5,5′-dibenzothiatricarbocyanine iodide; 7-dimethylamino-1-methyl-4-methoxy-8-azaquinolone-2; 7-dimethylamino-4-methylquinolone-2; 2-(4-(4-dimethylaminophenyl)-1,3-butadienyl)-3-ethylbenzothiazolium perchlorate; 3-diethylamino-7-diethyliminophenoxazonium perchlorate; 2-(1-naphthyl)-5-phenyloxazole; 2,2′-p-phenylen-bis(5-phenyloxazole); rhodamine 700; rhodamine 800; pyrene; chrysene; rubrene; coronene, or the like, or combinations comprising at least one of the foregoing dyes. Dyes are generally used in amounts of about 0.1 to about 10 ppm, based on 100 parts by weight of the thermoplastic composition.

Anti-drip agents may also be used, for example a fibril forming or non-fibril forming fluoropolymer such as polytetrafluoroethylene (PTFE). The anti-drip agent may be encapsulated by a rigid copolymer as described above, for example SAN. PTFE encapsulated in SAN is known as TSAN. Encapsulated fluoropolymers may be made by polymerizing the encapsulating polymer in the presence of the fluoropolymer, for example, in an aqueous dispersion. TSAN may provide significant advantages over PTFE, in that TSAN may be more readily dispersed in the composition. A suitable TSAN may comprise, for example, about 50 wt. % PTFE and about 50 wt. % SAN, based on the total weight of the encapsulated fluoropolymer. The SAN may comprise, for example, about 75 wt. % styrene and about 25 wt. % acrylonitrile based on the total weight of the copolymer. Alternatively, the fluoropolymer may be pre-blended in some manner with a second polymer, such as for, example, an aromatic polycarbonate resin or SAN to form an agglomerated material for use as an anti-drip agent. Either method may be used to produce an encapsulated fluoropolymer.

Where a foam is desired, suitable blowing agents include, for example, low boiling halohydrocarbons and those that generate carbon dioxide; blowing agents that are solid at room temperature and when heated to temperatures higher than their decomposition temperature, generate gases such as nitrogen, carbon dioxide or ammonia gas, such as azodicarbonamide, metal salts of azodicarbonamide, 4,4′-oxybis(benzenesulfonylhydrazide), sodium bicarbonate, ammonium carbonate, or the like; or combinations comprising at least one of the foregoing blowing agents.

The thermoplastic compositions may be manufactured by methods generally available in the art, for example, in one embodiment, in one manner of proceeding, the polycarbonate, impact modifier, flame retardant additive and anti-static agent, and any other optional components (such as antioxidants,mold release agents, and the like) are first blended, in a Henschel^Tmhigh speed mixer or other suitable mixer/blender. Other low shear processes including but not limited to hand mixing may also accomplish this blending. The blend is then fed into the throat of a twin-screw extruder via a hopper. Alternatively, one or more of the components may be incorporated into the composition by feeding directly into the extruder at the throat and/or downstream through a sidestuffer. Such additives may also be compounded into a masterbatch with a desired polymeric resin and fed into the extruder. The extruder is generally operated at a temperature higher than that necessary to cause the composition to flow. The extrudate is immediately quenched in a water bath and pelletized. The pellets, so prepared, when cutting the extrudate may be one-fourth inch long or less as desired. Such pellets may be used for subsequent molding, shaping, or forming.

Shaped, formed, or molded articles comprising the polycarbonate compositions are also provided. The polycarbonate compositions may be molded into useful shaped articles by a variety of means such as injection molding, extrusion, rotational molding, blow molding and thermoforming to form articles such as, for example, computer and business machine housings such as housings for monitors, handheld electronic device housings such as housings for cell phones, electrical connectors, and components of lighting fixtures, ornaments, home appliances, roofs, greenhouses, sun rooms, swimming pool enclosures, electronic device casings and signs and the like. In addition, the polycarbonate compositions may be used for such applications as automotive panel and trim. Examples of suitable articles are exemplified by but are not limited to aircraft, automotive, truck, military vehicle (including automotive, aircraft, and water-borne vehicles), scooter, and motorcycle exterior and interior components, including panels, quarter panels, rocker panels, trim, fenders, doors, deck-lids, trunk lids, hoods, bonnets, roofs, bumpers, fascia, grilles, mirror housings, pillar appliques, cladding, body side moldings, wheel covers, hubcaps, door handles, spoilers, window frames, headlamp bezels, headlamps, tail lamps, tail lamp housings, tail lamp bezels, license plate enclosures, roof racks, and running boards; enclosures, housings, panels, and parts for outdoor vehicles and devices; enclosures for electrical and telecommunication devices; outdoor furniture; aircraft components; boats and marine equipment, including trim, enclosures, and housings; outboard motor housings; depth finder housings; personal water-craft; jet-skis; pools; spas; hot tubs; steps; step coverings; building and construction applications such as glazing, roofs, windows, floors, decorative window furnishings or treatments; treated glass covers for pictures, paintings, posters, and like display items; wall panels, and doors; counter tops; protected graphics; outdoor and indoor signs; enclosures, housings, panels, and parts for automatic teller machines (ATM); computer; desk-top computer; portable computer; lap-top computer; hand held computer housings; monitor; printer; keyboards; FAX machine; copier; telephone; phone bezels; mobile phone; radio sender; radio receiver; enclosures, housings, panels, and parts for lawn and garden tractors, lawn mowers, and tools, including lawn and garden tools; window and door trim; sports equipment and toys; enclosures, housings, panels, and parts for snowmobiles; recreational vehicle panels and components; playground equipment; shoe laces; articles made from plastic-wood combinations; golf course markers; utility pit covers; light fixtures; lighting appliances; network interface device housings; transformer housings; air conditioner housings; cladding or seating for public transportation; cladding or seating for trains, subways, or buses; meter housings; antenna housings; cladding for satellite dishes; coated helmets and personal protective equipment; coated synthetic or natural textiles; coated painted articles; coated dyed articles; coated fluorescent articles; coated foam articles; and like applications. The invention further contemplates additional fabrication operations on said articles, such as, but not limited to, molding, in-mold decoration, baking in a paint oven, lamination, and/or thermoforming. The articles made from the composition of the present invention may be used widely in automotive industry, home appliances, electrical components, and telecommunications.

The compositions are further illustrated by the following non-limiting examples, which were prepared from the components set forth in Table 1.

TABLE 1

Material
Description
Source

PC-1
BPA polycarbonate resin made by an interfacial process with a
GE Plastics

number average molecular weight of 21,800

Daltons measured on a PC standard basis

PC-2
BPA polycarbonate resin made by an interfacial process
GE Plastics

with a number average molecular weight of 30,000

Daltons measured on a PC standard basis

BABS
Bulk ABS comprising about 16–17 wt. % polybutadiene
GE Plastics

and 83–84 wt. % SAN

BPADP
Bisphenol A bis(diphenylphosphate)
Daihaichi/

Asahi Denko

TSAN
PTFE encapsulated in SAN (50 wt. % PTFE, 50 wt. %
GE Plastics

SAN)

AS-1
Tetrabutylphosphonium perfluorobutylsulfonate
DuPont

AS-2
Dodecylbenzene phosphonium sulfonate (EPA202)
Takemoto Oil

& Fat Co., Ltd.

AS-3
Polyether-ester-amide block copolymer (trade name
Sanyo

PELESTAT NC6321)
Chemical

Industries, Ltd.

Each of the sample compositions was prepared according to formulations in Table 2. All amounts are in weight percent unless otherwise noted. In each of the examples, samples were prepared by melt extrusion on a Werner & Pfleiderer™ 25 mm co-rotating twin screw extruder at a nominal barrel temperature of about 260° C., about 1 bar of vacuum, and about 450 rpm. The extrudate was pelletized and dried at about 85° C. for at least 4 hours. To make test specimens, the dried pellets were injection molded on an Engel ES500/110 HLV 110-ton injection molding machine at a nominal barrel temperature of 260° C.

The compositions of Table 2 were tested for mechanical properties, surface resistivity and flame retardance. The details of these tests used in the examples are known to those of ordinary skill in the art, and may be summarized as follows:

Melt volume rate (MVR) was determined at 260° C. using a 2.16-kilogram weight, over 10 minutes, in accordance with ASTM D1238. The preheat time used was 6 minutes.

Heat Deflection Temperature (HDT) is a relative measure of a material's ability to perform for a short time at elevated temperatures while supporting a load. The test measures the effect of temperature on stiffness: a standard test specimen is given a defined surface stress and the temperature is raised at a uniform rate. Heat Deflection Test (HDT) was determined per ASTM D648, using 6.4 mm thick bar subjected to 1.82 MPa.

Notched Izod Impact strength (NII) was determined on 3.2 mm (one-eighth inch) bars per ASTM D256. Izod Impact Strength ASTM D256 is used to compare the impact resistances of plastic materials. The results are defined as the impact energy in Joules used to break the test specimen, divided by the specimen area at the notch. Results are reported in J/m.

Percent ductility was determined on 3.2 mm thick NII test bars at room temperature using the impact energy as well as stress whitening of the fracture surface. Generally, significant stress whitening of the fractured surface accompanied by gross deformation at the fractured tip can indicate ductile failure mode; conversely, lack of significant stress whitening of the fractured surface accompanied by gross deformation at the fractured tip can indicate brittle failure mode. Ten bars were tested, and percent ductility is expressed as a percentage of impact bars that exhibited ductile failure mode. Ductility tends to decrease with temperature, and the ductile-brittle transition temperature is the temperature at which the possibility of ductile failure is equal to the possibility of brittle failure (that is, % ductility equals 50%).

Tensile properties such as Tensile Stress and Tensile Elongation at Break were determined using 4 mm thick molded tensile bars tested per ISO 527 at a pull rate of 1 mm/min. until 1% strain, followed by a rate of 50 mm/min. until the sample broke. It is also possible to measure at 5 mm/min. if desired for the specific application, but the samples measured in these experiments were measured at 50 mm/min. Tensile Strength results are reported as MPa, and Tensile Elongation at Break is reported as a percentage.

Surface Resistivity was measured according to ASTM D257. Surface resistivity is the resistance to leakage current along the surface of an insulating material. The electrical resistance is measured between two parallel electrodes in contact with the specimen surface and separated by a distance equal to the contact length of the electrodes. The resistivity is therefore the quotient of the potential gradient, in V/m, and the current per unit of electrode length, A/m. It can also be referred to as the ratio of the voltage drop per unit length to the surface current per unit width for electric current flowing along a surface, expressed in ohms. Since the four ends of the electrodes define a square, the lengths in the quotient cancel and surface resistivities are reported in ohms, although it is common to see the more descriptive unit of ohms per square (often also used to difference between surface resistance and surface resistivity).

Flammability tests were performed following the procedure of Underwriter's Laboratory Bulletin 94 entitled “Tests for Flammability of Plastic Materials, UL94.” According to this procedure, materials may be classified as HB, V0, V1, V2, 5VA and/or 5 VB on the basis of the test results obtained for five samples at the specified sample thicknesses. The criteria for each of these flammability classifications are described below.

V0: In a sample placed so that its long axis is 180 degrees to the flame, the average period of flaming and/or smoldering after removing the igniting flame does not exceed five seconds and none of the vertically placed samples produces drips of burning particles that ignite absorbent cotton, and no specimen burns up to the holding clamp after flame or after glow. Five bar flame out time (FOT) is the sum of the flame out time for five bars, each lit twice for a maximum flame out time of 50 seconds. FOTI is the average flame out time after the first light. FOT2 is the average flame out time after the second light.

V1, V2, FOT: In a sample placed so that its long axis is 180 degrees to the flame, the average period of flaming and/or smoldering after removing the igniting flame does not exceed twenty-five seconds and, for a V1 rating, none of the vertically placed samples produces drips of burning particles that ignite absorbent cotton. The V2 standard is the same as V1, except that drips are permitted. Five bar flame out time (FOT) is the sum of the flame out time for five bars, each lit twice for a maximum flame out time of 250 seconds.

5VB: a flame is applied to a vertically fastened, 5-inch (127 mm) by 0.5-inch (12.7 mm) test bar of a given thickness above a dry, absorbent cotton pad located 12 inches (305 mm) below the bar. The thickness of the test bar is determined using calipers with 0.1 mm accuracy. The flame is a 5-inch (127 mm) flame with an inner blue cone of 1.58 inches (40 mm). The flame is applied to the test bar for 5 seconds so that the tip of the blue cone touches the lower corner of the specimen. The flame is then removed for 5 seconds. Application and removal of the flame is repeated for until the specimen has had five applications of the same flame. After the fifth application of the flame is removed, a timer (T-0) is started and the time that the specimen continues to flame (after-flame time), as well as any time the specimen continues to glow after the after-flame goes out (after-glow time), is measured by stopping T-0 when the after-flame stops, unless there is an after-glow and then T-0 is stopped when the after-glow stops. The combined after-flame and after-glow time must be less than or equal to 60 seconds after five applications of a flame to a test bar, and there may be no drips that ignite the cotton pad. The test is repeated on 5 identical bar specimens. If there is a single specimen of the five that does not comply with the time and/or no-drip requirements then a second set of 5 specimens are tested in the same fashion. All of the specimens in the second set of 5 specimens must comply with the requirements in order for material in the given thickness to achieve the 5VB standard.

TABLE 2

Units
1
2
3
4
5

Component

PC-1
%
35.25
35.25
35.25
35.25
35.25

PC-2
%
35.44
35.44
35.44
35.44
35.44

BABS
%
17.0
17.0
17.0
17.0
17.0

BPADP
%
11.0
11.0
11.0
11.0
11.0

TSAN
%
0.65
0.65
0.65
0.65
0.65

AS-1
%
0
0.75
1.5
0
0

AS-2
%
0
0
0
2
0

AS-3
%
0
0
0
0
5

Others*
%
0.66
0.66
0.66
0.66
0.66

AS-1 mol
Mol/
0
1.34
2.69
0
0

amount
100 kg

Physical

Properties

MVR
cm³/
17.2
16.5
19.4
27.4
15.6

260° C./
10 min

2.16 kg

ASTM HDT
° C.
91.1
92
91
92
94

¼″

ASTM NII @
J/m
663
610
535
166
653

23° C.

Ductility
%
100
100
100
0
100

Tensile Stress
MPa
59
58
56
57
57

Tensile
%
74
90
90
90
100

Elongation

Surface
Ohm
6E+15
2E+15
2E+13
2E+15
2E+15

Resistivity

UL94V0
Pass/
Pass
Pass
Pass
Fail
Fail

at 1.5 mm
Fail

*OTHERS - standard additives, including hindered phenol antioxidant (0.08 wt %), phosphite stabilizer (0.08 wt %) and pentaerythritol tetrastearate (0.5 wt %) were also added to the compositions.

The results of Table 2 show that the samples comprising the Tetrabutylphosphonium perfluorobutylsulfonate (AS-1) as an antistatic agent at a level of 0.75 or 1.5 wt. % (1.34 or 2.69 mol per 100 kg of the composition) had significantly better surface resistivity while maintaining the mechanical properties and flame retardancy. The samples having either no antistatic agent (Example 1, which is a control sample) or a comparative material (Examples 4 and 5, which had AS-2 or AS-3 as the anti-static agent) had worse surface resistivity and poor flame retardant properties. Example 4 also had poor Notched Izod Impact as well. The molar amount of anti-static agent (AS-1, AS-2 or AS-3) in the compositions is based on 100 kg of the combined composition, excluding the anti-static agent. The weight percent is based on 100% of the combined composition, excluding the anti-static agent.

FIG. 1 graphically shows the difference in surface resistivity of Examples 1, 2 and 3, which have no AS-1, 0.75 wt. % AS-1 and 1.5 wt. % AS-1 respectively. FIGS. 3 and 4 show the reduction in dust build up on a molded chip after 45 days exposure when the anti-static agent, AS-1, is added. The molded chip of FIG. 2, which has no anti-static agent, has considerably more dust than the molded chip of FIG. 3, which has a low level of AS-1. The molded chip of FIG. 4, which comprises the composition of Example 3 having 1.5 wt. % AS-1, has no noticeable dust on the chip after 45 days exposure.

Additional samples were produced using the materials in Table 1 in the amounts shown below in Table 3 at different levels of antistatic agent AS-1 to determine the optimum operating range. All amounts are parts by weight. The molar amount of anti-static agent (AS-1) is based on 100 kg of the combined composition, excluding the anti-static agent. The weight percent is based on 100% of the combined composition, excluding the anti-static agent. The compositions were molded and tested, as detailed above, and the results are shown in Table 3 below.

TABLE 3

Units
6
7
8
9
10
11
12

Component

PC-1
%
35.25
35.25
35.25
35.25
35.25
35.25
35.25

PC-2
%
35.44
35.44
35.44
35.44
35.44
35.44
35.44

BABS
%
17.0
17.0
17.0
17.0
17.0
17.0
17.0

BPADP
%
11.0
11.0
11.0
11.0
11.0
11.0
11.0

TSAN
%
0.65
0.65
0.65
0.65
0.65
0.65
0.65

AS-1
%
0
0.5
1.0
2.0
3.0
5.0
7.0

Others*
%
0.66
0.66
0.66
0.66
0.66
0.66
0.66

AS-1 (mol
Mol/
0
0.90
1.79
3.58
5.38
8.96
12.54

amount)
100 kg

Physical

Properties

MVR
cm³/10 min
17.2
19.8
19.0
21.3
22.3
26.2
30.0

260° C./2.16 kg

ASTM HDT
° C.
91.1
91.6
92.8
90.1
92.5
94.4
90.4

¼″

ASTM NII @
J/m
663
604
607
447
435
406
386

23° C.

Tensile Stress
MPa
59.0
58.8
58.2
57.0
56.0
53.6
51.7

Tensile
%
74
54
68
87
87
28
12

Elongation

Surface
Ohm
6E+15
1E+15
9E+13
2E+13
2E+13
3E+12
4E+12

Resistivity

*OTHERS - standard additives, including hindered phenol antioxidant (0.08 wt %), phosphite stabilizer (0.08 wt %) and pentaerythritol tetrastearate (0.5 wt %) were also added to the compositions.

The results in Table 3 show that the addition of tetrabutylphosphonium perfluorobutylsulfonate (AS-1) as an anti-static agent up to a level of 3.0 wt. % (or 5.38 mol per 100 kg of the composition) helped to reduce or improve surface resistivity while maintaining the mechanical properties. At higher levels of antistatic agent, the mechanical properties were adversely affected. Example 6 is a control sample having no anti-static agent. The physical properties of Examples 11 and 12, which have 5.0 and 7.0 wt. % (8.96 and 12.54 mol/100 kg of the composition) AS-1 respectively, start to deteriorate, as indicated by the significant drop in Tensile Elongation and the lower Notched Izod Impact results.

While typical embodiments have been set forth for the purpose of illustration, the foregoing descriptions should not be deemed to be a limitation on the scope herein. Accordingly, various modifications, adaptations, and alternatives may occur to one skilled in the art without departing from the spirit and scope herein.

Thermoplastic Polycarbonate Compositions With Improved Static Resistance

Information

Publication Number

Date Filed

Date Published

Inventors

Original Assignees

CPC

US Classifications

International Classifications

Abstract

Description

Claims