Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
1999-09-09
2002-11-26
Buttner, David J. (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C524S127000, C524S141000, C525S065000, C525S067000, C525S146000
Reexamination Certificate
active
06486241
ABSTRACT:
The present invention concerns a polycarbonate resin composition containing polycarbonate resin, and more specifically, a polycarbonate resin composition showing outstanding moisture resistance and little decrease in tensile properties.
Polymer alloys composed of a blend of polycarbonate resin (PC) and acrylonitrile-butadiene-styrene (ABS) resin are widely used in applications such as electrical and electronic products and office automation equipment. In recent years, with the increasing requirement for miniaturization and light weight of such products, new molding methods have been attempted, and resins used in such products must increasingly have thin-wall properties, precision molding properties, and high flame retardancy. There has been rapid growth in manufacturing and use in these applications in southeast Asia in recent years. Because of the use and storage of products in high-humidity environments in areas such as southeast Asia, there is frequently a risk of physical deterioration due to low moisture resistance of the resins used.
Generally speaking, polymer alloys containing blends of PC and ABS resin cannot be said to show high moisture resistance. In the case of flame-retardant resin compositions in particular, it is not possible to maintain a high level of moisture resistance.
The present invention provides a flame-retardant resin composition showing moisture resistance which is superior to that of conventional blended alloys of PC and ABS resin.
As a result of thorough research on polycarbonate resin compositions in order to solve the aforementioned problem, the inventors discovered that by using an ABS copolymer in which the alkali metal content of the polycarbonate composition is low and adding an epoxy stabilizer, it is possible to improve moisture resistance, thus arriving at the present invention. Moreover, concerning flame-retardant resin compositions, they discovered that a flame-retardant resin composition showing particularly high moisture resistance compared to conventional compositions could be obtained by using flame retardants in which the acid value of the phosphoric ester was low.
Specifically, the present invention comprises a polycarbonate resin composition containing (A) 1 to 99 parts by weight of polycarbonate resin having a viscosity average molecular weight of 10,000 to 100,000, and (B) 1 to 99 parts by weight of (B-1) a copolymer having as its component parts (a) an aromatic vinyl monomer component, (b) a cyanide vinyl monomer component, and (c) a rubber-like polymer, or (B-2) a copolymer having as its component parts (a) an aromatic vinyl monomer component and (b) a cyanide vinyl monomer component, the aforementioned B-2 being a copolymer having a weight average molecular weight of 30,000 to 200,000 and containing an amount of various alkali metals of 1 ppm or less, and blended in (C) 0 to 40 parts by weight of a phosphoric ester compound with respect to a total of 100 parts by weight of the aforementioned components (A) and (B).
Moreover, by adding to this resin composition 0 to 3 parts by weight of (E) an epoxy stabilizer with respect to a total of 100 parts by weight of the aforementioned components (A) and (B), and as an optional component, 0.01 to 3 parts, preferably 0.05 to about 2, and more preferably from about 0.1 to about 1, by weight of (F) polytetrafluoroethylene with respect to a total of 100 parts by weight of the aforementioned components (A) and (B), a polycarbonate resin composition having even more outstanding moisture resistance can be produced.
The following is an explanation of the various components of the resin composition of the present invention. The polycarbonate resin used in the present invention is an aromatic polycarbonate manufactured by the commonly-known phosgene method or the melt polymerization method (cf. Japanese Unexamined Patent Applications S63-215763 and H2-124934). Examples of the diphenols used as raw materials include 2,2-bis(4-hydroxyphenyl)propane (referred to as bisphenol A); 2,2-bis(3,5-dibromo-4-hydroxyphenyl)propane; 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane; 1,1-bis(4-hydroxyphenyl)cyclohexane; 1,1-bis(3,5-dimethyl-4-hydroxyphenyl)cyclohexane; 1,1-bis(3,5-dimethyl-4-hydroxyphenyl)cyclohexane; 1,1-bis(4-hydroxyphenyl)decane; 1,4-bis(4-hydroxyphenyl)propane; 1,1-bis(4-hydroxyphenyl)cyclododecane; 1,1-bis(3,5-dimethyl-4-hydroxyphenyl)cyclododecane; 4,4-dihydroxydiphenyl ether; 4,4-thiodiphenol; 4,4-dihydroxy-3,3-dichlorodiphenyl ether; and 4,4-dihydroxy-2,5-dihydroxydiphenyl ether. Moreover, examples of precursor substances for introducing the carbonate include phosgene and diphenylcarbonate.
In the present invention, the viscosity average molecular weight (Mv) of the polycarbonate resin should be 10,000 or more, preferably 16,000 or more and more preferably 21,000 or more, with a viscosity average molecular weight of 22,000 being particularly preferred. The upper limit of viscosity average molecular weight should be 100,000, and in practice, this limit is usually about 40,000. In the present invention, viscosity average molecular weight was measured based on intrinsic viscosity (limiting viscosity) in methylene chloride at 20° C., and it was calculated as follows using the Mark-Houwink viscosity formula:
Limiting viscosity=K(Mv)
a
In the formula, K and a are constants; K=1.23 E-4, a=0.83.
Component (B-1) is a copolymer containing (a) an aromatic vinyl monomer component, (b) a cyanide vinyl monomer component, and (c) a rubber-like polymer.
Examples of (a) the aromatic vinyl monomer include styrene, &agr;-methylstyrene,
o-, m-, or p-methylstyrene, vinyl xylene, monochlorostyrene, dichlorostyrene, monobromostyrene, dibromostyrene, fluorostyrene, p-tert-butylstyrene, ethylstyrene, and vinyl naphthalene, and these substances may be used individually or in combinations of two or more; &agr;-methylstyrene should preferably be used.
Examples of (b) the cyanide vinyl monomer component include acrylonitrile and methacrylonitrile, and these substances may be used individually or in combinations of two or more. There are no particular restrictions on the composition ratio of this component, and this ratio should be selected according to the application in question.
Examples of (c) the rubber-like polymer include polybutadiene, polyisoprene, styrene-butadiene random copolymer and block copolymer, hydrogenates of said block copolymers, diene rubbers such as acrylonitrile-butadiene copolymer and butadiene-isoprene copolymer, ethylene-propylene random copolymer and block copolymer, copolymers of ethylene and &agr;-olefins, ethylene-unsaturated carboxylic acid ester copolymers such as ethylene-methacrylate and ethylene-butylacrylate, acrylate ester-butadiene copolymers, for example, acrylic elastomeric polymers such as butylacrylate-butadiene copolymer, copolymers of ethylene and aliphatic vinyl such as ethylene-vinyl acetate, and ethylene-propylene non-conjugated diene terpolymers such as ethylene-propylene-hexadiene copolymer, butylene-isoprene copolymer, and chlorinated polyethylene, and these substances may be used individually or in combinations of two or more. Preferred rubber-like polymers are ethylene-propylene non-conjugated diene terpolymer, diene rubber, and acrylic elastomeric polymers, with polybutadiene and styrene-butadiene copolymer being particularly preferred.
In addition to the aforementioned components (a), (b), and (c) of component (B), one may also use (d) monomers which are copolymerizable with these components in amounts which do not adversely affect the purpose of the present invention. Examples of such copolymerizable monomers include &agr;,&bgr;-unsaturated carboxylic acids such as acrylic acid and methacrylic acid, &agr;,&bgr;-unsaturated carboxylic acid esters such as methyl(meth)acrylate, ethyl(meth)acrylate, propyl(meth)acrylate, butyl(meth)acrylate, 2-ethyl(meth)acrylate, and 2-ethylhexylmethacrylate; &agr;,&bgr;-unsaturated dicarboxylic anhydrides such as maleic anhydride and itaconic anhydride; imide compounds of &agr;,&bgr;-unsaturated dicarboxylic
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