Patent Application
20070072961
This invention is directed to thermoplastic compositions comprising aromatic polycarbonate, their method of manufacture, and method of use thereof, and in particular filled thermoplastic polycarbonate compositions having improved mechanical properties.
Aromatic polycarbonates are useful in the manufacture of articles and components for a wide range of applications, from automotive parts to electronic appliances. Impact modifiers are commonly added to aromatic polycarbonates to improve the toughness of the compositions. The impact modifiers often have a relatively rigid thermoplastic phase and an elastomeric (rubbery) phase, and may be formed by bulk or emulsion polymerization. Polycarbonate compositions comprising acrylonitrile-butadiene-styrene (ABS) impact modifiers are described generally, for example, in U.S. Pat. No. 3,130,177 and U.S. Pat. No. 3,130,177. Polycarbonate compositions comprising emulsion polymerized ABS impact modifiers are described in particular in U.S. Publication No. 2003/0119986. U.S. Publication No. 2003/0092837 discloses use of a combination of a bulk polymerized ABS and an emulsion polymerized ABS.
Of course, a wide variety of other types of impact modifiers for use in polycarbonate compositions have also been described. While suitable for their intended purpose of improving toughness, many impact modifiers may also adversely affect other properties, such as impact and flame performance in flame retardant compositions.
One known method of increasing stiffness in polycarbonates is with the addition of fillers, such as talc and mica. A problem with mineral filled polycarbonate compositions and blends of polycarbonate compositions is that the filler reduces performance, such as impact and toughness. There remains a continuing need in the art, therefore, for impact-modified filled thermoplastic polycarbonate compositions having a combination of good physical properties, such as impact strength, flow, flex modulus, and ductility, and optionally, flame performance.
In one embodiment, a thermoplastic composition comprises in combination a polycarbonate component; a functionalized silane coupling agent; a filler; and optionally an impact modifier, a polycarbonate-polysiloxane copolymer and/or a flame retardant.
In another embodiment, a thermoplastic composition comprises in combination a polycarbonate component; a functionalized silane coupling agent; an impact modifier; a filler; and optionally a polycarbonate-polysiloxane copolymer and/or a flame retardant.
In another embodiment, an article comprises the above thermoplastic composition.
In still another embodiment, a method of manufacture of an article comprises molding, extruding, or shaping the above thermoplastic composition.
In still another embodiment, a method for the manufacture of a thermoplastic composition having improved impact strength and other mechanical properties, and optionally, improved flame performance, the method comprising admixture of a polycarbonate, a functionalized silane coupling agent, a filler, and optionally an impact modifier, a polycarbonate-polysiloxane copolymer and/or a flame retardant.
It has been discovered by the inventors hereof that use of a specific type of functionalized silane coupling agent in a filled polycarbonate composition or a filled, impact modified polycarbonate composition, provides a greatly improved balance of physical properties such as impact strength, toughness and flex modulus to filled thermoplastic compositions containing polycarbonate. The particular functionalized silane coupling agent used in the composition of the invention has the formula: (X)3-n(CH3)nSi—R—Y, wherein R is monovalent hydrocarbon having from 1 to 8 carbon atoms; Y is a functional group selected from the group consisting of OCOC(R1)═CH2 (acrylate) and CH═CH2 (vinyl), wherein R1 is hydrogen or a monovalent hydrocarbon having from 1 to 8 carbon atoms; X is a hydrolytic group selected from the group consisting of CH3O—, C2H5O—, and CH3OC2H4O—; and n is 0 or 1.
The filled thermoplastic compositions of the invention also have good flame performance if a flame retardant is optionally added to the composition. The improvement in physical properties without significantly adversely affecting flow, and optionally flame performance, is particularly unexpected, as the physical properties and flame performance of similar compositions with different silane coupling agents or without any silane coupling agent can be significantly worse. It has further been discovered that an advantageous combination of other physical properties, in addition to good impact strength, can be obtained by use of the specific combination of materials.
As used herein, the terms “polycarbonate” and “polycarbonate resin” means compositions having repeating structural carbonate units of formula (1):
in which at least about 60 percent of the total number of R1 groups are aromatic organic radicals and the balance thereof are aliphatic, alicyclic, or aromatic radicals. In one embodiment each R1 is an aromatic organic radical and, more specifically, a radical of formula (2):
-A1-Y1-A2- (2)
wherein each of A1 and A2 is a monocyclic divalent aryl radical and Y1 is a bridging radical having one or two atoms that separate A1 from A2. In an exemplary embodiment, one atom separates A1 from A2. Illustrative non-limiting examples of radicals of this type are —O—, —S—, —S(O)—, —S(O2)—, —C(O)—, methylene, cyclohexylmethylene, 2-[2.2.1]-bicycloheptylidene, ethylidene, isopropylidene, neopentylidene, cyclohexylidene, cyclopentadecylidene, cyclododecylidene, and adamantylidene. The bridging radical Y1 may 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, which includes dihydroxy compounds of formula (3)
HO-A1-Y1-A2-OH (3)
wherein Y1, A1 and A2 are as described above. Also included are bisphenol compounds of general formula (4):
wherein Ra and Rb each 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 Xa represents one of the groups of formula (5):
wherein Rc and Rd each independently represent a hydrogen atom or a monovalent linear or cyclic hydrocarbon group and Re is 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 others known in the art. Combinations comprising at least one of the foregoing dihydroxy compounds may also be used.
A nonexclusive list of specific examples of the types of bisphenol compounds that may be represented by formula (3) includes 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 bisphenol compounds may also be used.
Branched polycarbonates are also useful, as well as blends comprising a linear polycarbonate and a branched polycarbonate. The branched polycarbonates may be prepared by adding a branching agent during polymerization, for example a polyfunctional organic compound 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-hydroxyphenylethane, 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 0.05-2.0 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.
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, for example, about 8 to about 10. The most commonly used water immiscible solvents include methylene chloride, 1,2-dichloroethane, chlorobenzene, toluene, and others known in the art. Suitable carbonate precursors include, for example, a carbonyl halide such as carbonyl bromide or carbonyl chloride, or a haloformate such as a bishaloformates of a dihydric phenol (for example, the bischloroformates of bisphenol A, hydroquinone, and others known in the art) or a glycol (for example, the bishaloformate of ethylene glycol, neopentyl glycol, polyethylene glycol, and others known in the art). Combinations comprising at least one of the foregoing types of carbonate precursors may also be used.
Among the exemplary phase transfer catalysts that may be used are catalysts of the formula (R3)4Q+X, wherein each R3 is the same or different, and is a C1-10 alkyl group; Q is a nitrogen or phosphorus atom; and X is a halogen atom or a C1-8 alkoxy group or C6-188 aryloxy 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 C1-8 alkoxy group or C6-188 aryloxy group. An effective 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. Generally, in the melt polymerization process, polycarbonates (or aromatic carbonate polymers) may be prepared by co-reacting, in a molten state, the aromatic dihydroxy reactant(s) and a diaryl carbonate ester, such as diphenyl carbonate, in the presence of a transesterification catalyst. As used herein, “melt process” means a method that relies on reacting the aromatic dihydroxy compound and the carbonate compound together at a sufficiently high temperature such that the mixture is molten in the substantial absence of a solvent. Volatile monohydric phenol is removed from the molten reactants by distillation and the polymer is isolated as a molten residue.
The aromatic dihydroxy compounds that can be used to form the aromatic carbonate polymers, are mononuclear or polynuclear aromatic compounds, containing as functional groups two hydroxy radicals, each of which can be attached directly to a carbon atom of an aromatic nucleus. Suitable dihydroxy compounds are, for example, resorcinol, 4-bromoresorcinol, hydroquinone, alkyl-substituted hydroquinone such as methylhydroquinone, 4,4′-dihydroxybiphenyl, 1,6-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, bis(4-hydroxyphenyl)methane, bis(4-hydroxyphenyl)diphenylmethane, bis(4-hydroxyphenyl)-1-naphthylmethane, 1,1-bis(4-hydroxyphenyl)methane, 1,1-bis(4-hydroxyphenyl)ethane, 1,2-bis(4-hydroxyphenyl)ethane, 1,1-bis(4-hydroxyphenyl)-1-phenylethane, 2,2-bis(4-hydroxyphenyl)propane (“bisphenol A”), 2-(4-hydroxyphenyl)-2-(3-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, bis(4-hydroxyphenyl)phenylmethane, 2,2-bis(4-hydroxy-1-methylphenyl)propane, 1,1-bis(4-hydroxy-tert-butylphenyl)propane, 2,2-bis(4-hydroxy-3-bromophenyl)propane, and 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, 2,7-dihydroxycarbazole and the like, as well as combinations and reaction products comprising at least one of the foregoing dihydroxy compounds.
In various embodiments, two or more different aromatic dihydroxy compounds or a copolymer of an aromatic dihydroxy compound with an aliphatic diol, with a hydroxy- or acid-terminated polyester or with a dibasic acid or hydroxy acid can be employed in the event a carbonate copolymer or terpolymer is desired. A copolymer, as used herein, encompasses combinations comprising two or more monomers. One example of copolymer is a combination of bisphenol-A, hydroquinone and methylhydroquinone.
In one specific embodiment, the polycarbonate is a linear homopolymer derived from bisphenol A, in which each of A1 and A2 is p-phenylene and Y1 is isopropylidene. The polycarbonates may have an intrinsic viscosity, as determined in chloroform at 25° C., of about 0.3 to about 1.5 deciliters per gram (dl/gm), specifically about 0.45 to about 1.0 dl/gm. The polycarbonates may have a weight average molecular weight of about 10,000 to about 200,000, specifically about 20,000 to about 100,000 as measured by gel permeation chromatography. The polycarbonates are substantially free of impurities, residual acids, residual bases, and/or residual metals that may catalyze the hydrolysis of polycarbonate.
“Polycarbonate” and “polycarbonate resin” as used herein further includes copolymers comprising carbonate chain units together with a different type of chain unit. Such copolymers may be random copolymers, block copolymers, dendrimers and others known in the art. One specific type of copolymer that may be used 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 E is a divalent radical derived from a dihydroxy compound, and may be, for example, a C2-10 alkylene radical, a C6-20 alicyclic radical, a C6-20 aromatic 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 divalent radical derived from a dicarboxylic acid, and may be, for example, a C2-10 alkylene radical, a C6-20 alicyclic radical, a C6-20 alkyl aromatic radical, or a C6-20 aromatic radical.
In one embodiment, E is a C2-6 alkylene radical. In another embodiment, E is derived from an aromatic dihydroxy compound of formula (7):
wherein each Rf is independently a halogen atom, a C1-10 hydrocarbon group, or a C1-10 halogen substituted hydrocarbon group, and n is 0 to 4. The halogen is preferably 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-tetrafluororesorcinol, 2,4,5,6-tetrabromo resorcinol, and others known in the art; 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-tetrafluorohydroquinone, 2,3,5,6-tetrabromo hydroquinone, and others known in the art; 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, E is a C2-6 alkylene 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).
The copolyester-polycarbonate resins are also prepared by interfacial polymerization. Rather than using 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, and mixtures thereof, it is possible to employ isophthaloyl dichloride, terephthaloyl dichloride, and mixtures thereof. The copolyester-polycarbonate resins may have an intrinsic viscosity, as determined in chloroform at 25° C., of about 0.3 to about 1.5 deciliters per gram (dl/gm), specifically about 0.45 to about 1.0 dl/gm. The copolyester-polycarbonate resins may have a weight average molecular weight of about 10,000 to about 200,000, specifically about 20,000 to about 100,000 as measured by gel permeation chromatography. The copolyester-polycarbonate resins are substantially free of impurities, residual acids, residual bases, and/or residual metals that may catalyze the hydrolysis of polycarbonate.
The polycarbonate component may further comprise, in addition to the polycarbonates described above, combinations of the polycarbonates with other thermoplastic polymers, for example combinations of polycarbonate homopolymers and/or copolymers with polyesters and others known in the art. As used herein, a “combination” is inclusive of all mixtures, blends, alloys, and others known in the art. 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.
Suitable polyesters are poly(alkylene esters) including poly(alkylene arylates) and poly(cycloalkylene esters). Poly(alkylene arylates) have a polyester structure according to formula (6) wherein T is a p-disubstituted arylene radical, and D is an alkylene radical. Useful esters are dicarboxylarylates include those derived from the reaction product of a dicarboxylic acid or derivative thereof wherein T is a substituted and/or unsubstituted 1,2-, 1,3-, and 1,4-phenylene; substituted and/or unsubstituted 1,4- and 1,5-naphthylenes; substituted and/or unsubstituted 1,4-cyclohexylene; and the like. Suitable alkylene radicals include those derived from the reaction product of a dihydroxy compound wherein D is a C2-30 alkylene radical having a straight chain, branched chain, cycloalkylene, alkyl-substituted cycloalkylene, a combination comprising one or more of these, and the like. Specifically useful alkylene radicals D are bis-(alkylene-disubstituted cyclohexane), such as, for example, 1,4-(cyclohexylene)dimethylene. Suitable polyesters include poly(alkylene terephthalates), where T is 1,4-phenylene. Examples of poly(alkylene terephthalates) include poly(ethylene terephthalate) (PET), poly(1,4-butylene terephthalate) (PBT), poly(propylene terephthalate) (PPT). Also useful are poly(alkylene naphthoates), such as poly(ethylene naphthanoate) (PEN), and poly(butylene naphthanoate), (PBN). A specifically suitable poly(cycloalkylene ester) is poly(cyclohexanedimethanol terephthalate) (PCT). Combinations comprising at least one of the foregoing polyesters may also be used. Also contemplated herein 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. Specifically useful ester units include different alkylene terephthalate units, which can be present in the polymer chain as individual units, or as blocks comprising multiple of the same units, i.e. blocks of specific poly(alkylene terephthalates).
Copolymers comprising repeating ester units of the above alkylene terephthalates with other suitable repeating ester groups are also useful. Suitable examples of such copolymers include poly(cyclohexanedimethanol terephthalate)-co-poly(ethylene terephthalate), abbreviated as PETG where the polymer comprises greater than or equal to 50 mole % of poly(ethylene terephthalate), and abbreviated as PCTG where the polymer comprises greater than 50 mole % of poly(cyclohexanedimethanol terephthalate). Suitable poly(cycloalkylene esters) can include poly(alkylene cyclohexanedicarboxylates). A specific example of a useful poly(alkylene cyclohexanedicarboxylates) polyester is poly(1,4-cyclohexane-dimethanol-1,4-cyclohexanedicarboxylate) (PCCD), having recurring units of the formula
wherein, as described using formula (6), D is a dimethylene cyclohexane radical derived from cyclohexane dimethanol, and T is a cyclohexane ring derived from cyclohexanedicarboxylate or a chemical equivalent thereof and is selected from the cis- or trans-isomer or a mixture of cis- and trans-isomers thereof. PCCD, where used, is generally completely miscible with the polycarbonate.
The blends of a polycarbonate and a polyester may comprise about 10 to about 99 wt. % polycarbonate and correspondingly about 1 to about 90 wt. % polyester, in particular a poly(alkylene terephthalate). In one embodiment, the blend comprises about 30 to about 70 wt. % polycarbonate and correspondingly about 30 to about 70 wt. % polyester. The foregoing amounts are based on the combined weight of the polycarbonate and polyester.
Although blends of polycarbonates with other polymers are contemplated, in one embodiment the polycarbonate component consists essentially of polycarbonate, for example, the polycarbonate component comprises polycarbonate homopolymers and/or polycarbonate copolymers, and no other resins that would significantly adversely impact the impact strength of the thermoplastic composition. In another embodiment, the polycarbonate component consists of polycarbonate, for example, is composed of only polycarbonate homopolymers and/or polycarbonate copolymers.
It has been found by the inventors hereof that a particular type of silane coupling agent, when combined with the polycarbonate, filler and optional impact modifier and/or flame retardant, can provide thermoplastic compositions having excellent physical properties and optionally flame retardance. Specifically, the silane coupling agent is a functionalized silane coupling agent having the formula: (X)3-n(CH3)nSi—R—Y, wherein R is monovalent hydrocarbon having from 1 to 8 carbon atoms; Y is a functional group selected from the group consisting of OCOC(R1)═CH2 (acrylate) and CH═CH2 (vinyl), wherein R1 is hydrogen or a monovalent hydrocarbon having from 1 to 8 carbon atoms; X is a hydrolytic group selected from the group consisting of CH3O—, C2H5O—, and CH3OC2H4O—, and n is 0 or 1.
Examples of the functionalized silane coupling agent suitable for use in the composition of the invention include, but are not limited to, vinyl alkoxy silanes and acrylate or methacrylate alkoxy silanes, such as vinyltriethoxysilane, vinylmethyldiethoxysilane, vinylmethyldimethoxysilane, vinyltris-(2-methoxyethoxy)silane, methacryloxypropyltrimethoxysilane, and methacryloxypropyltriethoxysilane. Particularly useful are vinyltriethoxysilane, vinyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, and γ-methacryloxypropyltriethoxysilane. Preferred functionality of the functionalized silane is vinyl and/or acrylate functionality.
The composition may further comprise an impact modifier. One type of impact modifier is a bulk polymerized ABS. The bulk polymerized ABS comprises an elastomeric phase comprising (i) butadiene and having a Tg of less than about 10° C., and (ii) a rigid polymeric phase having a Tg of greater than about 15° C. and comprising a copolymer of a monovinylaromatic monomer such as styrene and an unsaturated nitrile such as acrylonitrile. Such ABS polymers may be prepared by first providing the elastomeric polymer, then polymerizing the constituent monomers 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.
Polybutadiene homopolymer may be used as the elastomer phase. Alternatively, the elastomer phase of the bulk polymerized ABS comprises butadiene copolymerized with up to about 25 wt. % of another conjugated diene monomer of formula (8):
wherein each Xb is independently C1-C5 alkyl. Examples of conjugated diene monomers that may be used are 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 others known in the art, as well as mixtures comprising at least one of the foregoing conjugated diene monomers. A specific conjugated diene is isoprene.
The elastomeric butadiene phase may additionally be copolymerized with up to 25 wt %, specifically up to about 15 wt. %, of another comonomer, for example monovinylaromatic monomers containing condensed aromatic ring structures such as vinyl naphthalene, vinyl anthracene and others known in the art, or monomers of formula (9):
wherein each Xc is independently hydrogen, C1-C12 alkyl, C3-C12 cycloalkyl, C6-C12 aryl, C7-C12 aralkyl, C7-C12 alkaryl, C1-C12 alkoxy, C3-C12 cycloalkoxy, C6-C12 aryloxy, chloro, bromo, or hydroxy, and R is hydrogen, C1-C5 alkyl, bromo, or chloro. Examples of suitable monovinylaromatic monomers copolymerizable with the butadiene include styrene, 3-methylstyrene, 3,5-diethylstyrene, 4-n-propylstyrene, alpha-methylstyrene, alpha-methyl vinyltoluene, alpha-chlorostyrene, alpha-bromostyrene, dichlorostyrene, dibromostyrene, tetra-chlorostyrene, and others known in the art, and combinations comprising at least one of the foregoing monovinylaromatic monomers. In one embodiment, the butadiene is copolymerized with up to about 12 wt. %, specifically about 1 to about 10 wt. % styrene and/or alpha-methyl styrene.
Other monomers that may be copolymerized with the butadiene 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-C5 alkyl, bromo, or chloro, and Xc is cyano, C1-C12 alkoxycarbonyl, C1-C12 aryloxycarbonyl, hydroxy carbonyl, and others known in the art. 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 others known in the art, 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 butadiene.
The particle size of the butadiene phase is not critical, and may be, for example about 0.01 to about 20 micrometers, specifically about 0.5 to about 10 micrometers, more specifically about 0.6 to about 1.5 micrometers may be used for bulk polymerized rubber substrates. Particle size may be measured by light transmission methods or capillary hydrodynamic chromatography (CHDF). The butadiene phase may provide about 5 to about 95 wt. % of the total weight of the ABS impact modifier copolymer, more specifically about 20 to about 90 wt. %, and even more specifically about 40 to about 85 wt. % of the ABS impact modifier, the remainder being the rigid graft phase.
The rigid graft phase comprises a copolymer formed from a styrenic monomer composition together with an unsaturated monomer comprising a nitrile group. As used herein, “styrenic monomer” includes monomers of formula (9) wherein each Xc is independently hydrogen, C1-C4 alkyl, phenyl, C7-C9 aralkyl, C7-C9 alkaryl, C1-C4 alkoxy, phenoxy, chloro, bromo, or hydroxy, and R is hydrogen, C1-C2 alkyl, bromo, or chloro. Specific examples styrene, 3-methylstyrene, 3,5-diethylstyrene, 4-n-propylstyrene, alpha-methylstyrene, alpha-methyl vinyltoluene, alpha-chlorostyrene, alpha-bromostyrene, dichlorostyrene, dibromostyrene, tetra-chlorostyrene, and others known in the art. Combinations comprising at least one of the foregoing styrenic monomers may be used.
Further as used herein, an unsaturated monomer comprising a nitrile group includes monomers of formula (10) wherein R is hydrogen, C1-C5 alkyl, bromo, or chloro, and Xc is cyano. Specific examples include acrylonitrile, ethacrylonitrile, methacrylonitrile, alpha-chloroacrylonitrile, beta-chloroacrylonitrile, alpha-bromoacrylonitrile, and others known in the art. Combinations comprising at least one of the foregoing monomers may be used.
The rigid graft phase of the bulk polymerized ABS may further optionally comprise other monomers copolymerizable therewith, including other monovinylaromatic monomers and/or 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). Specific comonomers include C1-C4 alkyl(meth)acrylates, for example methyl methacrylate.
The rigid copolymer phase will generally comprise about 10 to about 99 wt. %, specifically about 40 to about 95 wt. %, more specifically about 50 to about 90 wt. % of the styrenic monomer; about 1 to about 90 wt. %, specifically about 10 to about 80 wt. %, more specifically about 10 to about 50 wt. % of the unsaturated monomer comprising a nitrile group; and 0 to about 25 wt. %, specifically 1 to about 15 wt. % of other comonomer, each based on the total weight of the rigid copolymer phase.
The bulk polymerized ABS copolymer may further comprise a separate matrix or continuous phase of ungrafted rigid copolymer that may be simultaneously obtained with the ABS. The ABS may comprise about 40 to about 95 wt. % elastomer-modified graft copolymer and about 5 to about 65 wt. % rigid copolymer, based on the total weight of the ABS. In another embodiment, the ABS may comprise about 50 to about 85 wt. %, more specifically about 75 to about 85 wt. % elastomer-modified graft copolymer, together with about 15 to about 50 wt. %, more specifically about 15 to about 25 wt. % rigid copolymer, based on the total weight of the ABS.
A variety of bulk polymerization methods for ABS-type resins are known. In multizone plug flow bulk processes, a series of polymerization vessels (or towers), consecutively connected to each other, providing multiple reaction zones. The elastomeric butadiene may be dissolved in one or more of the monomers used to form the rigid phase, and the elastomer solution is fed into the reaction system. During the reaction, which may be thermally or chemically initiated, the elastomer is grafted with the rigid copolymer (for example, SAN). Bulk copolymer (referred to also as free copolymer, matrix copolymer, or non-grafted copolymer) is also formed within the continuous phase containing the dissolved rubber. As polymerization continues, domains of free copolymer are formed within the continuous phase of rubber/comonomers to provide a two-phase system. As polymerization proceeds, and more free copolymer is formed, the elastomer-modified copolymer starts to disperse itself as particles in the free copolymer and the free copolymer becomes a continuous phase (phase inversion). Some free copolymer is generally occluded within the elastomer-modified copolymer phase as well. Following the phase inversion, additional heating may be used to complete polymerization. Numerous modifications of this basis process have been described, for example in U.S. Pat. No. 3,511,895, which describes a continuous bulk ABS process that provides controllable molecular weight distribution and microgel particle size using a three-stage reactor system. In the first reactor, the elastomer/monomer solution is charged into the reaction mixture under high agitation to precipitate discrete rubber particle uniformly throughout the reactor mass before appreciable cross-linking can occur. Solids levels of the first, the second, and the third reactor are carefully controlled so that molecular weights fall into a desirable range. U.S. Pat. No. 3,981,944 discloses extraction of the elastomer particles using the styrenic monomer to dissolve/disperse the elastomer particles, prior to addition of the unsaturated monomer comprising a nitrile group and any other comonomers. U.S. Pat. No. 5,414,045 discloses reacting in a plug flow grafting reactor a liquid feed composition comprising a styrenic monomer composition, an unsaturated nitrile monomer composition, and an elastomeric butadiene polymer to a point prior to phase inversion, and reacting the first polymerization product (grafted elastomer) therefrom in a continuous-stirred tank reactor to yield a phase inverted second polymerization product that then can be further reacted in a finishing reactor, and then devolatilized to produce the desired final product.
In addition to the bulk polymerized ABS, other impact modifiers known in the art may be used in the composition of the invention. Other impact modifiers include elastomer-modified graft copolymers comprising (i) an elastomeric (for example, rubbery) polymer substrate having a Tg less than about 10° C., more specifically less than about −10° C., or more specifically about −40° to −80° C., and (ii) a rigid polymeric superstrate grafted to the elastomeric polymer substrate. 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 C1-8 alkyl(meth)acrylates; elastomeric copolymers of C1-8 alkyl(meth)acrylates with butadiene and/or styrene; or combinations comprising at least one of the foregoing elastomers.
Suitable conjugated diene monomers for preparing the elastomer phase are of formula (8) above wherein each Xb is independently hydrogen, C1-C5 alkyl, and others known in the art. 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 others known in the art, 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 others known in the art, or monomers of formula (9) above, wherein each Xc is independently hydrogen, C1-C12 alkyl, C3-C12 cycloalkyl, C6-C12 aryl, C7-C12 aralkyl, C7-C12 alkaryl, C1-C12 alkoxy, C3-C12 cycloalkoxy, C6-C12 aryloxy, chloro, bromo, or hydroxy, and R is hydrogen, C1-C5 alkyl, 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, combinations comprising at least one of the foregoing compounds, and others known in the art. Styrene and/or alpha-methylstyrene are commonly 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-C5 alkyl, bromo, or chloro, and Xc is cyano, C1-C12 alkoxycarbonyl, C1-C12 aryloxycarbonyl, hydroxy carbonyl, and others known in the art. 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 others known in the art, 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.
Certain (meth)acrylate monomers may also be used to provide the elastomer phase, including cross-linked, particulate emulsion homopolymers or copolymers of C1-16 alkyl(meth)acrylates, specifically C1-9 alkyl(meth)acrylates, in particular C4-6 alkyl acrylates, for example n-butyl acrylate, t-butyl acrylate, n-propyl acrylate, isopropyl acrylate, 2-ethylhexyl acrylate, and others known in the art, and combinations comprising at least one of the foregoing monomers. The C1-16 alkyl (meth)acrylate monomers may optionally be polymerized in admixture with up to 15 wt. % of comonomers of generic formulas (8), (9), or (10) as broadly described above. Exemplary comonomers include but are not limited to butadiene, isoprene, styrene, methyl methacrylate, phenyl methacrylate, phenethylmethacrylate, 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 others known in the art, 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. The elastomer phase may be a particulate, moderately cross-linked copolymer derived from conjugated butadiene or C4-9 alkyl acrylate rubber, and preferably has a gel content greater than 70%. Also suitable are copolymers derived from mixtures of butadiene with styrene, acrylonitrile, and/or C4-6 alkyl acrylate rubbers.
The elastomeric phase may provide about 5 to about 95 wt. % of the elastomer-modified graft copolymer, more specifically about 20 to about 90 wt. %, and even more specifically about 40 to about 85 wt. %, 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 broadly 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, and others known in the art, or combinations comprising at least one of the foregoing monovinylaromatic monomers. Suitable comonomers include, for example, the above broadly described monovinylic monomers and/or monomers of the general formula (10). In one embodiment, R is hydrogen or C1-C2 alkyl, and Xc is cyano or C1-C12 alkoxycarbonyl. 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 others known in the art, and combinations comprising at least one of the foregoing comonomers.
In one specific embodiment, the rigid graft phase is formed from styrene or alpha-methyl styrene copolymerized with ethyl acrylate and/or methyl methacrylate. In other specific embodiments, the rigid graft phase is formed from styrene copolymerized with; styrene copolymerized with methyl methacrylate; and styrene copolymerized with methyl methacrylate and acrylonitrile.
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 additional elastomer-modified graft copolymer. Typically, such impact modifiers comprise about 40 to about 95 wt. % elastomer-modified graft copolymer and about 5 to about 65 wt. % rigid (co)polymer, based on the total weight of the impact modifier. In another embodiment, such impact modifiers comprise about 50 to about 85 wt. %, more specifically about 75 to about 85 wt. % rubber-modified rigid copolymer, together with about 15 to about 50 wt. %, more specifically about 15 to about 25 wt. % rigid (co)polymer, based on the total weight of the impact modifier.
Specific examples of elastomer-modified graft copolymers that differ from the bulk polymerized ABS include but are not limited to acrylonitrile-styrene-butyl acrylate (ASA), methyl methacrylate-acrylonitrile-butadiene-styrene (MABS), methyl methacrylate-butadiene-styrene (MBS), and acrylonitrile-ethylene-propylene-diene-styrene (AES). The MBS resins may be prepared by emulsion polymerization of methacrylate and styrene in the presence of polybutadiene as is described in U.S. Pat. No. 6,545,089, which process is summarized below.
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(Rd)C(O)OCH2CH2Re, wherein Rd is hydrogen or a C1-C9 linear or branched hydrocarbyl group and Re is a branched C3-C16 hydrocarbyl 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, for example, 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 others known in the art, alone or in combination. The polymerizable alkenyl-containing organic material may be, for example, a monomer of formula (9) or (10), for example, styrene, alpha-methylstyrene, acrylonitrile, methacrylonitrile, or an unbranched (meth)acrylate such as methyl methacrylate, 2-ethylhexyl methacrylate, methyl acrylate, ethyl acrylate, n-propyl acrylate, and others known in the art, 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, for example, (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 an 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 microns. At least one branched acrylate rubber monomer is then polymerized with the silicone rubber particles, optionally in 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.
In practice, any of the above described impact modifiers may be used if desired. Processes for the formation of the 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.
In one embodiment, the impact modifier is prepared by an emulsion polymerization process that avoids the use or production of any species that degrade polycarbonates. In another embodiment the impact modifier is prepared by an emulsion polymerization process that is free of basic species, for example species such as alkali metal salts of C6-30 fatty acids, for example sodium stearate, lithium stearate, sodium oleate, potassium oleate, and others known in the art, alkali metal carbonates, amines such as dodecyl dimethyl amine, dodecyl amine, and others known in the art, and ammonium salts of amines. Such materials are commonly used as polymerization aids, for example, 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, C1-22 alkyl or C7-25 alkylaryl sulfonates, C1-22 alkyl or C7-25 alkylaryl sulfates, C1-22 alkyl or C7-25 alkylaryl phosphates, substituted silicates, and combinations comprising at least one of the foregoing surfactants. A specific surfactant is a C6-16, specifically a C8-12 alkyl 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 addition, the impact modifier composition may optionally further comprise an ungrafted rigid copolymer. The rigid copolymer is additional to any rigid copolymer present in the bulk polymerized ABS or additional 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 others known in the art, 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.
The rigid copolymer may be manufactured by bulk, suspension, or emulsion polymerization, and is substantially free of impurities, residual acids, residual bases or residual metals that may catalyze the hydrolysis of polycarbonate. 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 average molecular weight of the rigid copolymer is about 70,000 to about 190,000.
The composition further comprises at least one filler. One useful class of fillers is the particulate fillers, which may be of any configuration, for example spheres, plates, fibers, acicular, flakes, whiskers, or irregular shapes. Suitable fillers typically have an average longest dimension of about 1 nanometer to about 500 micrometers, specifically about 10 nanometers to about 100 micrometers. The average aspect ratio (length:diameter) of some fibrous, acicular, or whisker-shaped fillers (e.g., glass or wollastonite) may be about 1.5 to about 1000, although longer fibers are also within the scope of the invention. The mean aspect ratio (mean diameter of a circle of the same area: mean thickness) of plate-like fillers (e.g., mica, talc, or kaolin) may be greater than about 5, specifically about 10 to about 1000, more specifically about 10 to about 200. Bimodal, trimodal, or higher mixtures of aspect ratios may also be used. Combinations of fillers may also be used.
The fillers may be of natural or synthetic, mineral or non-mineral origin, provided that the fillers have sufficient thermal resistance to maintain their solid physical structure at least at the processing temperature of the composition with which it is combined. Suitable fillers include clays, nanoclays, carbon black, wood flour either with or without oil, various forms of silica (precipitated or hydrated, fumed or pyrogenic, vitreous, fused or colloidal, including common sand), glass, metals, inorganic oxides (such as oxides of the metals in Periods 2, 3, 4, 5 and 6 of Groups Ib, IIb, IIIa, IIIb, IVa, IVb (except carbon), Va, VIa, VIIa and VIII of the Periodic Table), oxides of metals (such as aluminum oxide, titanium oxide, zirconium oxide, titanium dioxide, nanoscale titanium oxide, aluminum trihydrate, vanadium oxide, and magnesium oxide), hydroxides of aluminum or ammonium or magnesium, carbonates of alkali and alkaline earth metals (such as calcium carbonate, barium carbonate, and magnesium carbonate), antimony trioxide, calcium silicate, diatomaceous earth, fuller earth, kieselguhr, mica, talc, slate flour, volcanic ash, cotton flock, asbestos, kaolin, alkali and alkaline earth metal sulfates (such as sulfates of barium and calcium sulfate), titanium, zeolites, wollastonite, titanium boride, zinc borate, tungsten carbide, ferrites, molybdenum disulfide, asbestos, cristobalite, aluminosilicates including Vermiculite, Bentonite, montmorillonite, Na-montmorillonite, Ca-montmorillonite, hydrated sodium calcium aluminum magnesium silicate hydroxide, pyrophyllite, magnesium aluminum silicates, lithium aluminum silicates, zirconium silicates, and combinations comprising at least one of the foregoing fillers. Suitable fibrous fillers include glass fibers, basalt fibers, aramid fibers, carbon fibers, carbon nanofibers, carbon nanotubes, carbon buckyballs, ultra high molecular weight polyethylene fibers, melamine fibers, polyamide fibers, cellulose fiber, metal fibers, potassium titanate whiskers, and aluminum borate whiskers.
Of these, calcium carbonate, talc, glass, glass fibers, quartz, carbon fibers, magnesium carbonate, mica, silicon carbide, kaolin, wollastonite, calcium sulfate, barium sulfate, titanium, silica, carbon black, ammonium hydroxide, magnesium hydroxide, aluminum hydroxide, and combinations comprising at least one of the foregoing are useful. It has been found that talc, mica, wollastonite, clay, silica, quartz, glass, and combinations comprising at least one of the foregoing fillers are of specific utility.
Alternatively, or in addition to a particulate filler, the filler 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.
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 R1 is 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 A1 and A2 is p-phenylene and Y1 is isopropylidene.
The polydiorganosiloxane blocks comprise repeating structural units of formula (11) (sometimes referred to herein as ‘siloxane’):
wherein each occurrence of R is same or different, and is a C1-13 monovalent organic radical. For example, R may be a C1-C13 alkyl group, C1-C13 alkoxy group, C2-C13 alkenyl group, C2-C13 alkenyloxy group, C3-C6 cycloalkyl group, C3-C6 cycloalkoxy group, C6-C10 aryl group, C6-C10 aryloxy group, C7-C13 aralkyl group, C7-C13 aralkoxy group, C7-C13 alkaryl group, or C7-C13 alkaryloxy group. Combinations of the foregoing R groups may be used in the same copolymer.
The value of D in formula (11) 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 40 to about 60. Where D is of a lower value, for example, 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, for example, 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 (12):
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-C30 arylene radical, wherein the bonds are directly connected to an aromatic moiety. Suitable Ar groups in formula (12) may be derived from a C6-C30 dihydroxyarylene 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:
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 (13)
wherein R and D are as defined above. R2 in formula (13) is a divalent C2-C8 aliphatic group. Each M in formula (9) may be the same or different, and may be a halogen, cyano, nitro, C1-C8 alkylthio, C1-C8 alkyl, C1-C8 alkoxy, C2-C8 alkenyl, C2-C8 alkenyloxy group, C3-C8 cycloalkyl, C3-C8 cycloalkoxy, C6-C10 aryl, C6-C10 aryloxy, C7-C12 aralkyl, C7-C12 aralkoxy, C7-C12 alkaryl, or C7-C12 alkaryloxy, 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; R2 is a dimethylene, trimethylene or tetramethylene group; and R is a C1-8 alkyl, 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, R2 is a divalent C1-C3 aliphatic group, and R is methyl.
These units may be derived from the corresponding dihydroxy polydiorganosiloxane (14):
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 (15),
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 (14) 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, for example, 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 equivalent molar amount of another polydiorganosiloxane, with the balance being polycarbonate. In a particular embodiment, the copolymer may comprise about 20 wt. % siloxane.
The polycarbonate-polysiloxane copolymers have a weight-average molecular weight (MW, measured, for example, by gel permeation chromatography, ultra-centrifugation, or light scattering) of about 10,000 g/mol to about 200,000 g/mol, specifically about 20,000 g/mol to about 100,000 g/mol.
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 modifiers, fillers, 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 30 to about 95 wt. % polycarbonate component, about 0.01 to about 5 wt. % silane coupling agent, about 0.5 to about 20 wt. % filler, and optionally, about 0.5 to about 30 wt. % impact modifier, and about 2 to about 20 wt. % flame retardant. In another embodiment, the thermoplastic composition comprises about 40 to about 85 wt. % polycarbonate component, about 0.03 to about 3 wt. % silane coupling agent, about 2 to about 25 wt. % filler, and optionally about 2 to about 20 wt. % impact modifier, and about 5 to about 18 wt. % flame retardant. In another embodiment, the thermoplastic composition comprises about 45 to about 80 wt. % polycarbonate component, about 0.1 to about 2 wt. % silane coupling agent, about 5 to about 20 wt. % filler, and optionally about 5 to about 15 wt. % impact modifier, and about 5 to about 15 wt. % flame retardant. The foregoing compositions may further optionally comprise 1 about 30 wt. %, specifically 2 to about 25 wt. %, more specifically about 5 to about 20 wt. %, even more specifically about 5 to about 15 wt. %, most specifically about 8 to about 15 wt. % of a polycarbonate-polysiloxane copolymer. All of the foregoing amounts are based on the combined weight of the polycarbonate, the impact modifier, the filler, and optionally the polycarbonate-polysiloxane copolymer and/or flame retardant.
As a specific example of the foregoing embodiments, there is provided a thermoplastic composition that comprises about 50 to about 70 wt. % of a polycarbonate component; about 0.1 to about 1 wt. % of a silane coupling agent; about 5 to about 15 wt. % of an impact modifier; about 5 to about 18 wt. % of filler; about 5 to about 15 wt. % of flame retardant; and optionally, 5 to about 15 wt. % of a polycarbonate-polysiloxane copolymer. Use of the foregoing amounts may provide compositions having enhanced impact strength, tensile elongation and toughness together with good flame retardance.
In addition to the foregoing components, the polycarbonate compositions may further comprise a flame retardant if flame performance is desired. Examples of flame retardants that are suitable for use in the invention include, for example, an organic phosphate and/or an organic compound 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 others known in the art.
Di- or polyfunctional aromatic phosphorus-containing compounds are also useful, for example, compounds of the formulas below:
wherein each G1 is independently a hydrocarbon having 1 to about 30 carbon atoms; each G2 is independently a hydrocarbon or hydrocarbonoxy having 1 to about 30 carbon atoms; each X is independently a bromine or chlorine; m 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 others known in the art. Methods for the preparation of the aforementioned di- or polyfunctional aromatic compounds are described in British Patent No. 2,043,083.
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. The organic phosphorus-containing flame retardants are generally present in amounts of about 0.5 to about 20 parts by weight, based on 100 parts by weight of the combined weight of the resins in the composition, exclusive of any filler.
The thermoplastic composition may be essentially free of chlorine and bromine, particularly chlorine and bromine flame retardants. “Essentially free of chlorine and bromine” as used herein refers to materials produced without the intentional addition of chlorine, bromine, and/or chlorine or bromine containing materials. It is understood however that in facilities that process multiple products a certain amount of cross contamination can occur resulting in bromine and/or chlorine levels typically on the parts per million by weight scale. With this understanding it can be readily appreciated that essentially free of bromine and chlorine may be defined as having a bromine and/or chlorine content of less than or equal to about 100 parts per million by weight (ppm), less than or equal to about 75 ppm, or less than or equal to about 50 ppm. When this definition is applied to the fire retardant it is based on the total weight of the fire retardant. When this definition is applied to the thermoplastic composition it is based on the total weight of resins in the composition.
Optionally, inorganic flame retardants may also be used, for example sulfonate salts such as potassium perfluorobutane sulfonate (Rimar salt) and potassium diphenylsulfone sulfonate; salts formed by reacting for example an alkali metal or alkaline earth metal (preferably 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, BaCO3, and BaCO3 or fluoro-anion complex such as Li3AlF6, BaSiF6, KBF4, K3AlF6, KAlF4, K2SiF6, and/or Na3AlF6 or the like. When present, inorganic flame retardant salts are generally present in amounts of about 0.01 to about 1.0 parts by weight, more specifically about 0.05 to about 0.5 parts by weight, based on 100 parts by weight of the combined weight of all the resins in the composition.
Exemplary suitable flame retardant compounds containing phosphorus-nitrogen bonds include phosphonitrilic chloride and tris(aziridinyl) phosphine oxide. When present, phosphorus-containing flame retardants are generally present in amounts of about 1 to about 20 parts by weight, based on 100 parts by weight of the combined weight of all the resins in the composition.
Halogenated materials may also be used as flame retardants, for example halogenated compounds and resins of the formula (16):
wherein R is an alkylene, alkylidene or cycloaliphatic linkage, for example, methylene, propylene, isopropylidene, cyclohexylene, cyclopentylidene, and others known in the art; an oxygen ether, carbonyl, amine, or a sulfur containing linkage, for example, sulfide, sulfoxide, sulfone, and others known in the art; or two or more alkylene or alkylidene linkages connected by such groups as aromatic, amino, ether, carbonyl, sulfide, sulfoxide, sulfone, and others known in the art groups; Ar and Ar′ are each independently a mono- or polycarbocyclic aromatic group such as phenylene, biphenylene, terphenylene, naphthylene, and others known in the art, wherein hydroxyl and Y substituents on 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; each Y is independently an organic, inorganic or organometallic radical, for example (1) a halogen such as chlorine, bromine, iodine, or fluorine, (2) an ether group of the general formula —OE, wherein E is a monovalent hydrocarbon radical similar to X, (3) monovalent hydrocarbon groups of the type represented by R or (4) other substituents, for example, nitro, cyano, and others known in the art, said substituents being essentially inert provided there be at least one and preferably two halogen atoms per aryl nucleus; each X is independently a monovalent C1-18 hydrocarbon group such as methyl, propyl, isopropyl, decyl, phenyl, naphthyl, biphenyl, xylyl, tolyl, benzyl, ethylphenyl, cyclopentyl, cyclohexyl, and others known in the art, each optionally containing 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; and each a, b, and c is independently a whole number, including 0, with the proviso that when b is 0, either a or c, but not both, may be 0, and when b is not 0, neither a nor c may be 0.
Included within the scope of the above formula are bisphenols of which the following are representative: bis(2,6-dibromophenyl)methane; 1,1-bis-(4-iodophenyl)ethane; 2,6-bis(4,6-dichloronaphthyl)propane; 2,2-bis(2,6-dichlorophenyl)pentane; bis(4-hydroxy-2,6-dichloro-3-methoxyphenyl)methane; and 2,2-bis(3-bromo-4-hydroxyphenyl)propane. Also included within the above structural formula are 1,3-dichlorobenzene, 1,4-dibrombenzene, 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 others known in the art. Also useful are oligomeric and polymeric halogenated aromatic compounds, such as a copolycarbonate of bisphenol A and tetrabromobisphenol A and a carbonate precursor, for example, phosgene. Metal synergists, for example, antimony oxide, may also be used with the flame retardant. When present, halogen containing flame retardants are generally used in amounts of about 1 to about 50 parts by weight, based on 100 parts by weight of the combined weight of all the resins in the composition.
Inorganic flame retardants may also be used, for example salts of C2-16 alkyl sulfonates such as potassium perfluorobutane sulfonate (Rimar salt), potassium perfluorooctane sulfonate, tetraethylammonium perfluorohexane sulfonate, and potassium diphenylsulfone sulfonate; salts such as CaCO3, BaCO3, and BaCO3; salts of fluoro-anion complex such as Li3AlF6, BaSiF6, KBF4, K3AlF6, KAlF4, K2SiF6, and Na3AlF6; and others known in the art. When present, inorganic flame retardant salts are generally present in amounts of about 0.01 to about 25 parts by weight, more specifically about 0.1 to about 10 parts by weight, based on 100 parts by weight of the combined weight of all the resins in the composition.
In addition to the polycarbonate component, the impact modifier composition, the filler and optionally the polycarbonate-polysiloxane copolymer and/or the flame retardant, the thermoplastic composition may include various additives such as other fillers, reinforcing agents, stabilizers, and others known in the art, with the proviso that the additives do not adversely affect the desired properties of the thermoplastic compositions.
In one embodiment, the additives may be treated to prevent or substantially reduce any degradative activity if desired. Such treatments may include coating with a substantially inert substance such as silicone, acrylic, or epoxy resins. Treatment may also comprise chemical passivation to remove, block, or neutralize catalytic sites. A combination of treatments may be used. Additives such as fillers, reinforcing agents, and pigments may be treated.
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. Suitable fillers or reinforcing agents that may be used include, for example, silicates and silica powders such as aluminum silicate (mullite), synthetic calcium silicate, zirconium silicate, fused silica, crystalline silica graphite, natural silica sand, and others known in the art; boron powders such as boron-nitride powder, boron-silicate powders, and others known in the art; oxides such as TiO2, aluminum oxide, magnesium oxide, and others known in the art; calcium sulfate (as its anhydride, dihydrate or trihydrate); calcium carbonates such as chalk, limestone, marble, synthetic precipitated calcium carbonates, and others known in the art; talc, including fibrous, modular, needle shaped, lamellar talc, and others known in the art; wollastonite; surface-treated wollastonite; glass spheres such as hollow and solid glass spheres, silicate spheres, cenospheres, aluminosilicate (atmospheres), and others known in the art; kaolin, including hard kaolin, soft kaolin, calcined kaolin, kaolin comprising various coatings known in the art to facilitate compatibility with the polymeric matrix resin, and others known in the art; single crystal fibers or “whiskers” such as silicon carbide, alumina, boron carbide, iron, nickel, copper, and others known in the art; 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, and others known in the art; sulfides such as molybdenum sulfide, zinc sulfide and others known in the art; barium species such as barium titanate, barium ferrite, barium sulfate, heavy spar, and others known in the art; metals and metal oxides such as particulate or fibrous aluminum, bronze, zinc, copper and nickel and others known in the art; flaked fillers such as glass flakes, flaked silicon carbide, aluminum diboride, aluminum flakes, steel flakes and others known in the art; 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 and others known in the art; 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 and others known in the art; organic fillers such as polytetrafluoroethylene (Teflon®) and others known in the art; 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) and others known in the art; as well as additional fillers and reinforcing agents such as mica, clay, feldspar, flue dust, fillite, quartz, quartzite, perlite, tripoli, diatomaceous earth, carbon black, and others known in the art, and combinations comprising at least one of the foregoing fillers and reinforcing agents. The fillers/reinforcing agents may be coated to prevent reactions with the matrix or may be chemically passivated to neutralize catalytic degradation site that might promote hydrolytic or thermal degradation.
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 and others known in the art. Fibrous fillers may be supplied in the form of, for example, rovings, woven fibrous reinforcements, such as 0-90 degree fabrics and others known in the art; non-woven fibrous reinforcements such as continuous strand mat, chopped strand mat, tissues, papers and felts and others known in the art; or three-dimensional reinforcements such as braids. Fillers are generally used in amounts of about 0 to about 100 parts by weight, based on 100 parts by weight of the combined weight of all the resins in the composition.
Suitable antioxidant additives include, for example, alkylated monophenols or polyphenols; alkylated reaction products of polyphenols with dienes, such as tetrakis[methylene(3,5-di-tert-butyl-4-hydroxyhydrocinnamate)]methane, and others known in the art; butylated reaction products of para-cresol or dicyclopentadiene; alkylated hydroquinones; hydroxylated thiodiphenyl ethers; alkylidene-bisphenols; benzyl species; 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; and others known in the art; and combinations comprising at least one of the foregoing antioxidants. Antioxidants are generally used in amounts of about 0.01 to about 1, specifically about 0.1 to about 0.5 parts by weight, based on 100 parts by weight of parts by weight of the combined weight of all the resins in the composition.
Suitable heat and color stabilizer additives include, for example, organophosphites such as tris(2,4-di-tert-butyl phenyl) phosphite. Heat and color stabilizers are generally used in amounts of about 0.01 to about 5, specifically about 0.05 to about 0.3 parts by weight, based on 100 parts by weight of parts by weight of the combined weight of all the resins in the composition.
Suitable secondary heat stabilizer additives include, for example thioethers and thioesters such as pentaerythritol tetrakis (3-(dodecylthio)propionate), pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], dilauryl thiodipropionate, distearyl thiodipropionate, dimyristyl thiodipropionate, ditridecyl thiodipropionate, pentaerythritol octylthiopropionate, dioctadecyl disulphide, and others known in the art, and combinations comprising at least one of the foregoing heat stabilizers. Secondary stabilizers are generally used in amount of about 0.01 to about 5, specifically about 0.03 to about 0.3 parts by weight, based upon 100 parts by weight of parts by weight of the combined weight of all the resins in the composition.
Light stabilizers, including ultraviolet light (UV) absorbing additives, may also be used. Suitable stabilizing additives of this type include, for example, benzotriazoles and hydroxybenzotriazoles such as 2-(2-hydroxy-5-methylphenyl)benzotriazole, 2-(2-hydroxy-5-tert-octylphenyl)-benzotriazole, 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)-phenol (CYASORB™ 5411 from Cytec), and TINUVIN™ 234 from Ciba Specialty Chemicals; hydroxybenzotriazines; hydroxyphenyl-triazine or—pyrimidine UV absorbers such as TINUVIN™ 1577 (Ciba), and 2-[4,6-bis(2,4-dimethylphenyl)-1,3,5-triazin-2-yl]-5-(octyloxy)-phenol (CYASORB™ 1164 from Cytec); non-basic hindered amine light stabilizers (hereinafter “HALS”), including substituted piperidine moieties and oligomers thereof, for example 4-piperidinol derivatives such as TINUVIN™ 622 (Ciba), GR-3034, TINUVIN™ 123, and TINUVIN™ 440; benzoxazinones, such as 2,2′-(1,4-phenylene)bis(4H-3,1-benzoxazin-4-one) (CYASORB™ UV-3638); hydroxybenzophenones such as 2-hydroxy-4-n-octyloxybenzophenone (CYASORB 531); oxanilides; cyanoacrylates such as 1,3-bis[(2-cyano-3,3-diphenylacryloyl)oxy]-2,2-bis[[(2-cyano-3,3-diphenylacryloyl)oxy]methyl]propane (UVINUL™ 3030) and 1,3-bis[(2-cyano-3,3-diphenylacryloyl)oxy]-2,2-bis[[(2-cyano-3,3-diphenylacryloyl)oxy]methyl]propane; and nano-size inorganic materials such as titanium oxide, cerium oxide, and zinc oxide, all with particle size less than about 100 nanometers; and others known in the art, and combinations comprising at least one of the foregoing stabilizers. Light stabilizers may be used in amounts of about 0.01 to about 10, specifically about 0.1 to about 1 parts by weight, based on 100 parts by weight of parts by weight of the polycarbonate component and the impact modifier composition. 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 combined weight of all the resins in the 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, for example, methyl stearate; stearyl stearate, pentaerythritol tetrastearate, and others known in the art; mixtures of methyl stearate and hydrophilic and hydrophobic nonionic surfactants comprising polyethylene glycol polymers, polypropylene glycol polymers, and copolymers thereof, for example, methyl stearate and polyethylene-polypropylene glycol copolymers in a suitable solvent; waxes such as beeswax, montan wax, paraffin wax and others known in the art; and poly alpha olefins such as Ethylflo 164, 166, 168, and 170. Such materials are generally used in amounts of about 0.1 to about 20 parts by weight, specifically about 1 to about 10 parts by weight, based on 100 parts by weight of the combined weight of all the resins in the 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 and others known in the art; sulfides such as zinc sulfides, and others known in the art; aluminates; sodium sulfo-silicates sulfates, chromates, and others known in the art; 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, and combinations comprising at least one of the foregoing pigments. Pigments may be coated to prevent reactions with the matrix or may be chemically passivated to neutralize catalytic degradation site that might promote hydrolytic or thermal degradation. Pigments are generally used in amounts of about 0.01 to about 10 parts by weight, based on 100 parts by weight of parts by weight of the combined weight of all the resins in the composition.
Suitable dyes are generally organic materials and include, for example, coumarin dyes such as coumarin 460 (blue), coumarin 6 (green), nile red and others known in the art; lanthanide complexes; hydrocarbon and substituted hydrocarbon dyes; polycyclic aromatic hydrocarbon dyes; scintillation dyes such as oxazole or oxadiazole dyes; aryl- or heteroaryl-substituted poly (C2-8) 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, and others known in the art; luminescent dyes such as 5-amino-9-diethyliminobenzo(a)phenoxazonium perchlorate; 7-amino-4-methylcarbostyryl; 7-amino-4-methylcoumarin; 7-amino-4-trifluoromethylcoumarin; 3-(2′-benzimidazolyl)-7-N,N-diethylaminocoumarin; 3-(2′-benzothiazolyl)-7-diethylaminocoumarin; 2-(4-biphenylyl)-5-(4-t-butylphenyl)-1,3,4-oxadiazole; 2-(4-biphenylyl)-5-phenyl-1,3,4-oxadiazole; 2-(4-biphenyl)-6-phenylbenzoxazole-1,3; 2,5-bis-(4-biphenylyl)-1,3,4-oxadiazole; 2,5-bis-(4-biphenylyl)-oxazole; 4,4′-bis-(2-butyloctyloxy)-p-quaterphenyl; p-bis(o-methylstyryl)-benzene; 5,9-diaminobenzo(a)phenoxazonium perchlorate; 4-dicyanomethylene-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran; 1,1′-diethyl-2,2′-carbocyanine iodide; 1,1′-diethyl-4,4′-carbocyanine iodide; 3,3′-diethyl-4,4′,5,5′-dibenzothiatricarbocyanine iodide; 1,1′-diethyl-4,4′-dicarbocyanine iodide; 1,1′-diethyl-2,2′-dicarbocyanine iodide; 3,3′-diethyl-9,11-neopentylenethiatricarbocyanine iodide; 1,3′-diethyl-4,2′-quinolyloxacarbocyanine iodide; 1,3′-diethyl-4,2′-quinolylthiacarbocyanine iodide; 3-diethylamino-7-diethyliminophenoxazonium perchlorate; 7-diethylamino-4-methylcoumarin; 7-diethylamino-4-trifluoromethylcoumarin; 7-diethylaminocoumarin; 3,3′-diethyloxadicarbocyanine iodide; 3,3′-diethylthiacarbocyanine iodide; 3,3′-diethylthiadicarbocyanine iodide; 3,3′-diethylthiatricarbocyanine iodide; 4,6-dimethyl-7-ethylaminocoumarin; 2,2′-dimethyl-p-quaterphenyl; 2,2-dimethyl-p-terphenyl; 7-dimethylamino-1-methyl-4-methoxy-8-azaquinolone-2; 7-dimethylamino-4-methylquinolone-2; 7-dimethylamino-4-trifluoromethylcoumarin; 2-(4-(4-dimethylaminophenyl)-1,3-butadienyl)-3-ethylbenzothiazolium perchlorate; 2-(6-(p-dimethylaminophenyl)-2,4-neopentylene-1,3,5-hexatrienyl)-3-methylbenzothiazolium perchlorate; 2-(4-(p-dimethylaminophenyl)-1,3-butadienyl)-1,3,3-trimethyl-3H-indolium perchlorate; 3,3′-dimethyloxatricarbocyanine iodide; 2,5-diphenylfuran; 2,5-diphenyloxazole; 4,4′-diphenylstilbene; 1-ethyl-4-(4-(p-dimethylaminophenyl)-1,3-butadienyl)-pyridinium perchlorate; 1-ethyl-2-(4-(p-dimethylaminophenyl)-1,3-butadienyl)-pyridinium perchlorate; 1-ethyl-4-(4-(p-dimethylaminophenyl)-1,3-butadienyl)-quinolium perchlorate; 3-ethylamino-7-ethylimino-2,8-dimethylphenoxazin-5-ium perchlorate; 9-ethylamino-5-ethylamino-10-methyl-5H-benzo(a) phenoxazonium perchlorate; 7-ethylamino-6-methyl-4-trifluoromethylcoumarin; 7-ethylamino-4-trifluoromethylcoumarin; 1,1′,3,3,3′,3′-hexamethyl-4,4′,5,5′-dibenzo-2,2′-indotricarboccyanine iodide; 1,1′,3,3,3′,3′-hexamethylindodicarbocyanine iodide; 1,1′,3,3,3′,3′-hexamethylindotricarbocyanine iodide; 2-methyl-5-t-butyl-p-quaterphenyl; N-methyl-4-trifluoromethylpiperidino-<3,2-g>coumarin; 3-(2′-N-methylbenzimidazolyl)-7-N,N-diethylaminocoumarin; 2-(1-naphthyl)-5-phenyloxazole; 2,2′-p-phenylen-bis(5-phenyloxazole); 3,5,3″″,5″″-tetra-t-butyl-p-sexiphenyl; 3,5,3″″,5″″-tetra-t-butyl-p-quinquephenyl; 2,3,5,6-1H,4H-tetrahydro-9-acetylquinolizino-<9,9a,1-gh>coumarin; 2,3,5,6-1H,4H-tetrahydro-9-carboethoxyquinolizino-<9,9a,1-gh>coumarin; 2,3,5,6-1H,4H-tetrahydro-8-methylquinolizino-<9,9a,1-gh>coumarin; 2,3,5,6-1H,4H-tetrahydro-9-(3-pyridyl)-quinolizino-<9,9a,1-gh>coumarin; 2,3,5,6-1H,4H-tetrahydro-8-trifluoromethylquinolizino-<9,9a,1-gh>coumarin; 2,3,5,6-1H,4H-tetrahydroquinolizino-<9,9a,1-gh>coumarin; 3,3′,2″,3′″-tetramethyl-p-quaterphenyl; 2,5,2″″,5′″-tetramethyl-p-quinquephenyl; P-terphenyl; P-quaterphenyl; nile red; rhodamine 700; oxazine 750; rhodamine 800; IR 125; IR 144; IR 140; IR 132; IR 26; IRS; diphenylhexatriene; diphenylbutadiene; tetraphenylbutadiene; naphthalene; anthracene; 9,10-diphenylanthracene; pyrene; chrysene; rubrene; coronene; phenanthrene and others known in the art, and combinations comprising at least one of the foregoing dyes. Dyes are generally used in amounts of about 0.1 parts per million to about 10 parts by weight, based on 100 parts by weight of parts by weight of the combined weight of all the resins in the composition.
Monomeric, oligomeric, or polymeric antistatic additives that may be sprayed onto the article or processed into the thermoplastic composition may be advantageously used. Examples of monomeric antistatic agents include long chain esters such as glycerol monostearate, glycerol distearate, glycerol tristearate, and others known in the art, sorbitan esters, and ethoxylated alcohols, alkyl sulfates, alkylarylsulfates, alkylphosphates, alkylaminesulfates, alkyl sulfonate salts such as sodium stearyl sulfonate, sodium dodecylbenzenesulfonate and others known in the art, fluorinated alkylsulfonate salts, betaines, and others known in the art. Combinations of the foregoing antistatic agents may be used. Exemplary polymeric antistatic agents include certain polyetheresters, each containing polyalkylene glycol moieties such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and others known in the art. Such polymeric antistatic agents are commercially available, and include, 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 polythiophene (commercially available from Bayer), which retains some of its 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, specifically about based on 100 parts by weight of the combined weight of all the resins in the composition.
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 25 dioxide ammonia gas, such as azodicarbonamide, metal salts of azodicarbonamide, 4,4′-oxybis(benzenesulfonylhydrazide), sodium bicarbonate, ammonium carbonate, and others known in the art, or combinations comprising at least one of the foregoing blowing agents. Blowing agents are generally used in amounts of about 0.5 to about 20 parts by weight, based on 100 parts by weight of the combined weight of all the resins in the 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 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. Antidrip agents are generally used in amounts of about 0.1 to about 10 parts by weight, based on 100 parts by weight of the combined weight of all the resins in the composition.
The thermoplastic compositions may be manufactured by methods generally available in the art, for example, in one embodiment, in one manner of proceeding, powdered polycarbonate or polycarbonates, other resin if used, impact modifier composition, and/or other optional components are first blended, optionally with chopped glass strands or other fillers in a high speed mixer, such as a Henschel™ or other mixer known in the art. 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 additives may be added to either the polycarbonate base materials or the ABS base material to make a concentrate, before this is added to the final product. The extruder is generally operated at a temperature higher than that necessary to cause the composition to flow, typically 500° F. (260° C.) to 650° F. (343° C.). The extrudate is immediately quenched in a water batch 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 thermoplastic compositions are also provided. The thermoplastic 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, and others known in the art.
The compositions find particular utility in business equipment and equipment housings, such as computers, DVDs, printers, and digital camera, as well as for extruded sheet applications, and others known in the art.
The thermoplastic compositions described herein have significantly improved balance of properties. In a particularly advantageous feature, the thermoplastic compositions may achieve improved flame performance with a good balance of physical properties and without significant degradation in ductility and impact strength. The compositions described herein may further have additional excellent physical properties and good processability.
The invention is further illustrated by the following non-limiting Examples, which were prepared from the components set forth in Table 1.
Samples were prepared by melt extrusion on a JSW twin screw extruder, TEX-44, using a nominal melt temperature of 260° C. (500° F.), and 400 rpm. The extrudate was pelletized and dried at about 90° C. (194° F.) for about 4 hours.
To make test specimens, the dried pellets were injection molded on an 85-ton injection molding machine at a nominal temp of 525° C. (977° F.), wherein the barrel temperature of the injection molding machine varied from about 285° C. (545° F.) to about 300° C. (572° F.). Specimens were tested in accordance with ASTM standards or other special test methods as described below.
Notched Izod Impact strength (NII) was determined on one-eighth inch (3.12 mm) bars per ASTM D256. Izod Impact Strength ASTM D 256 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.
The thermoplastic polycarbonate compositions of the invention have a good balance of properties, and optionally, good flame performance, including a notched Izod Impact of greater than about 50 J/m, specifically greater than about 60 J/m, specifically greater than about 70 J/m, determined at 23° C. using a 3.2 mm thick bar per ASTM D256, a Flexural Modulus of at least 3500 MPa measured according to ASTM D790, and a toughness of at least about 4.0.
Flexural Modulus was determined using a one-fourth inch (4 mm) thick bar, pursuant to ASTM D790, at a speed of 2.5 mm/min.
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 a flat, 4 mm thick bar, molded Tensile bar subjected to 1.82 MPa.
Tensile elongation to break was determined using a 4 mm thick molded tensile bar tested per ASTM D638 using Type 13.2 mm bars
Toughness (Flex strain) was measured by using a flex-bending test on one-eighth inch (3.2 mm) ASTM IZOD bar with a test span of 30 mm at the speed of 2.5 mm/min. The toughness or flex strain is the maximum flexural strain before breaking.
Flammability tests were performed following the procedure of Underwriter's Laboratory Bulletin 94 entitled “Tests for Flammability of Plastic Materials, UL94”. Several ratings can be applied based on the rate of burning, time to extinguish, ability to resist dripping, and whether or not drips are burning. According to this procedure, materials may be classified as HB, V0, UL94 V1, V2, 5VA and/or 5VB on the basis of the test results obtained for five samples. The criteria for the flammability classifications or “flame resistance” tested for these compositions 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. 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.
V1: 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 none of the vertically placed samples produces drips of burning particles that ignite absorbent cotton. Five bar flame out time is the sum of the flame out time for five bars, each lit twice for a maximum flame out time of 250 seconds.
Samples were produced according to the method described above using the materials in Table 1, and testing according to the test methods previously described. The sample formulations and test results are shown in Table 2 below.
*the composition additionally included a stabilization package containing stabilizer and mold release
The above results illustrate that compositions in accordance with the present invention having a small amount of the particular vinyl or methacrylate functionalized silane coupling agent of the invention exhibit significant improvement in the impact results while also achieving the UL 94 V0 rating at a thickness of less than or equal to 1.2 mm, specifically a thickness of 0.8 mm. Blends without the preferred functionalized silane coupling agent of the invention, such as Comparative Examples 3, 4 and 5, exhibit a poor balance of properties, having poor impact, toughness and tensile elongation. The physical properties and the balance of properties are similar to the compositions having no silane coupling agent. Additionally, Comparative Example 4 achieves only a V1 UL94 rating at 0.8 mm. Comparing Example 6 and Comparative Example 7 shows that even with a small amount of filler and no polycarbonate-polysiloxane copolymer, the addition of the functionalized silane coupling agent improves the physical properties of the composition, particularly the toughness and the notched Izod impact.
As used herein, the terms “first,” “second,” and others known in the art do not denote any order or importance, but rather are used to distinguish one element from another, and the terms “the”, “a” and “an” do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item. All ranges disclosed herein for the same properties or amounts are inclusive of the endpoints, and each of the endpoints is independently combinable. All cited patents, patent applications, and other references are incorporated herein by reference in their entirety.
The modifier “about” used in connection with a quantity is inclusive of the stated value and has the meaning dictated by the context (for example, 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, and that the description includes instances where the event occurs and instances where it does not.
While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.
