Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
2000-11-13
2002-11-05
Buttner, David J. (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
active
06476127
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a thermoplastic molding composition and more particularly to a composition containing polycarbonate and grafted rubber.
SUMMARY OF THE INVENTION
A thermoplastic molding composition suitable for preparing molded articles having improved properties, most notably high ductility and impact strength at low temperature, is disclosed. The composition contains a resinous blend of aromatic polycarbonate and a mixture of at least two grafted rubbers. The mixture of grafted rubbers contains a “small-mode” component having a weight average particle size of less than 0.3 microns and a “large-mode” component having a weight average particle size of 0.3 microns or larger. The inventive composition is characterized in the absence of flaky filler having an aspect ratio is at least 1.7 and particle size of 1-100 microns therefrom.
TECHNICAL BACKGROUND OF THE INVENTION
Thermoplastic molding compositions containing grafted rubber, such as ABS, and polycarbonate resin are known. Commercial products based on such compositions, notably Bayblend compositions that are available from Bayer Corporation, have long enjoyed wide market acceptance. U.S. Pat. Nos. 3,954,905 and 4,560,725 are noted to have disclosed relevant compositions. Also known are compositions which include ABS components, the rubber particles of which conform to bimodal size distributions. The art is noted to include U.S. Pat. No. 3,509,237 which disclosed a composition containing first and second graft copolymers having a rubber substrate and a superstrate of an interpolymer of a monovinylidene aromatic hydrocarbon and an unsaturated nitrile. The first and second graft copolymers have a number average particle size, of 0.8 to 2.0 microns and 0.01 to 0.25 microns respectively. The first graft is said to be a product of suspension polymerization and the second is produced by emulsion. U.S. Pat. No. 4,677,162 is noted for its disclosed composition, which contains polycarbonate, a graft copolymer and an impact modifier. While the graft copolymer entails particles averaging more than 0.75 microns, the impact modifier entailed in the working examples embraces a second graft copolymer having presently relevant chemical makeup and particle size. JP (Kokai) 8 193157 is noted to have disclosed a flame retardant thermoplastic resin composition that contains 15-70 parts by weight (pbw) of rubber reinforced vinyl-based resin that contains 1-5 pbw of small particle size rubber (weight average particle size is less than 0.3 &mgr;m (micron) and 3 to 10 pbw of a large particle size rubber, of which the particle size is at least 0.3 micron but not larger than 2 microns. The composition also contains polycarbonate (30-85 pbw) and per 100 parts by weight of such composition it contains 5 to 30 pbw of a flaky filler, such as talc, mica, wollastonite and glass flake, having an aspect ratio is at least 2 and the particle size is 1-100 microns. The present invention is characterized in, among others, the absence of such flaky filler having aspect ratio of at least 1.7. The absence of such flaky filler from the composition of the present invention renders these composition greater ductility—see the experimental section below.
DETAILED DESCRIPTION OF THE INVENTION
The inventive composition contains a resinous blend of about 60 to 80 percent polycarbonate resin and 20 to 40 percent of a mixture of at least two grafted rubbers. In a preferred embodiment, the blend contains 65 to 75 percent polycarbonate and 25 to 35 percent of the mixture; in all instances, the percents are in relation to the weight of the blend. The mixture of grafted rubbers contains a “small-mode” component (ABS-s) having a weight average particle size smaller than 0.3 microns, preferably about 0.15 to 0.28 microns, and a “large-mode” component (ABS-I), wherein weight average particle size is at least 0.3 micron, preferably about 0.35 to 0.65 micron. The weight ratio ABS-s/ABS-I in the mixture ranges from 3/27 to 7.5/22.5,preferably 3/27 to 5/25. In the preferred embodiments, ABS-s is a product of the well-known emulsion polymerization process and ABS-I is a product of the known mass, more preferably continuous mass, polymerization process. The inventive composition is characterized in the absence therefrom of flaky filler having an aspect ratio is at least 2 and the particle size is 1-100 microns.
The aromatic polycarbonate resins useful in the context of the present invention include homopolycarbonates and copolycarbonates and mixtures thereof. The suitable polycarbonates have a weight average molecular weight of 10,000 to 200,000, preferably 20,000 to 80,000 and their melt flow rate, per ASTM D-1238 at 300° C., is about 1 to about 65 g/10 min., preferably about 2 to 24 g/10 min. These resins may be prepared, for example, by the known diphasic interface process from a carbonic acid derivative such as phosgene and dihydroxy compounds by polycondensation (see German Offenlegungsschriften 2,063,050; 2,063,052; 1,570,703; 2,211,956; 2,211,957 and 2,248,817; French Patent 1,561,518; and the monograph H. Schnell, “Chemistry and Physics of Polycarbonates”, Interscience Publishers, New York, N.Y., 1964, all incorporated herein by reference).
In the present context, dihydroxy compounds suitable for the preparation of the polycarbonates of the inventor conform to the structural formulae (1) or (2).
wherein
A denotes an alkylene group with 1 to 8 carbon atoms, an alkylidene group with 2 to 8 carbon atoms, a cycloalkylene group with 5 to 15 carbon atoms, a cycloalkylidene group with 5 to 15 carbon atoms, a carbonyl group, an oxygen atom, a sulfur atom, —SO—, or —SO
2
— or a radical conforming to
e and g both denote the number 0 to 1; Z denotes F, Cl, Br or C
1-4
-alkyl and if several
Z radicals are substituents in one aryl radical, they may be identical or different from one another;
d denotes an integer of from 0 to 4; and
f denotes an integer of from 0 to 3.
Among the dihydroxy compounds useful in the practice of the invention are hydroquinone, resorcinol, bis-(hydroxyphenyl)-alkanes, bis-(hydroxyphenyl)-ethers, bis-(hydroxyphenyl)-ketones, bis-(hydroxy-phenyl)-sulfoxides, bis-(hydroxyphenyl)-sulfides, bis-(hydroxyphenyl)-sulfones, and &agr;, &agr;-bis-(hydroxyphenyl)-diisopropylbenzenes, as well as their nuclear-alkylated compounds. These and further suitable aromatic dihydroxy compounds are described, for example, in U.S. Pat. Nos. 5,126,428; 5,104,723; 5,041,521; 5,034,457; 3,028,356; 2,999,835; 3,148,172; 2,991,273; 3,271,367; and 2,999,846, all incorporated herein by reference.
Further examples of suitable bisphenols are 2,2-bis-(4-hydroxy-phenyl)-propane (bisphenol A), 2,4-bis-(4-hydroxyphenyl)-2-methyl-butane, 1,1-bis-(4-hydroxyphenyl)-cyclohexane, &agr;, &agr;′-bis-(4-hydroxy-phenyl)-p-diisopropylbenzene, 2,2-bis-(3-methyl-4-hydroxyphenyl)-propane, 2,2-bis-(3-chloro-4-hydroxyphenyl)-propane, bis-(3,5-dimethyl-4-hydroxyphenyl)-methane, 2,2-bis-(3,5-dimethyl4-hydroxyphenyl)-propane, bis-(3,5-dimethyl-4-hydroxyphenyl)-sulfide, bis-(3,5-dimethyl-4-hydroxy-phenyl)-sulfoxide, bis-(3,5-dimethyl-4-hydroxyphenyl)-sulfone, dihydroxy-benzophenone, 2,4-bis-(3,5-dimethyl-4-hydroxyphenyl)-cyclohexane, &agr;,&agr;′-bis-(3,5-dimethyl-4-hyd roxyphenyl)-p-diisopropyl-benzene and 4,4′-sulfonyl diphenol.
Examples of particularly preferred aromatic bisphenols are 2,2-bis-(4-hydroxyphenyl)-propane, 2,2-bis-(3,5-dimethyl-4-hydroxyphenyl)-propane and 1,1-bis-(4-hydroxyphenyl)-cyclohexane.
The most preferred bisphenol is 2,2-bis-(4-hydroxyphenyl)-propane (bisphenol A).
The polycarbonates of the invention may entail in their structure units derived from one or more of the suitable bisphenols.
Among the resins suitable in the practice of the invention is included phenolphthalein-based polycarbonate, copolycarbonates and terpolycar-bonates such as are described in U.S. Pat. Nos. 3,036,036 and 4,210,741, both incorporated by reference herein.
The polycarbonates of the invention may also be branched by condensing therein small quantities, e
Janarthanan Venkatarayaloo
Spangler Lora L.
Bayer Corporation
Buttner David J.
Franks James R.
Gil Joseph C.
Preis Aron
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