Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Patent
1996-06-13
1998-08-25
Zitomer, Fred
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
525 70, 525 71, 525 78, 525 80, C08L 5104
Patent
active
057984140
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a resin composition excelled in impact strength, planar impact strength in particular, moldability, heat resistance (heat distortion resistance) and surface gloss.
BACKGROUND ART
Alloys of acrylonitrile-styrene-(.alpha.-methylstyrene)-(phenylmaleimide) copolymers and graft-copolymers made by grafting acrylonitrile and styrene to polybutadiene are generally called ABS resins and are widely used for their excellent moldability et cetera. When heat resistance is especially demanded, .alpha.-methylstyrene-copolymerized ABS resins or maleimide-copolymerized ABS resins are used lately.
In the field of home electric appliances which are known as a main source of demand for ABS resins, there has been a strong desire for high-gloss materials which are known to impart added values to such products.
The physical properties of ABS resins depend largely on such factors as resin composition, molecular weight, and composition, gel content, particle size, particle size distribution and content of the incorporated rubber. For the desired high-gloss feature, it is known to be effective to decrease the rubber content as well as its particle size but it is accompanied by such problems as deterioration of impact strength and mechanical properties known as features of ABS resins. Heat resistance of ABS resins is improved by copolymerization of .alpha.-methylstyrene or maleimide but this, in turn, causes lowering of impact strength.
In paying attention to the significance of rubber particle size distribution, attempts have been made to use various rubbery polymers for improving gloss with positive preservation of impact strength.
For example, joint use of a small particle size rubber and a large particle size rubber proposed in 1 Japanese Laid-open Patent Publication No. 144747/'75, joint use of a low-gel small particle size rubber and a high-gel medium particle size rubber proposed in 2 Japanese Laid-open Patent Publication No. 11713/'87, use of rubber of a given particle size distribution with majority of rubber particles being fine proposed in 3 Japanese Laid-open Patent Publication No. 264658/'88, joint use of a rubber medium in particle size and rubber large in particle size, a few microns, proposed in 4 Japanese Laid-open Patent Publication No. 232138/'84, use of a graft polymer prepared by simultaneous grafting to a mixture of rubber particles small and medium in size proposed in 5 Japanese Laid-open Patent Publication No. 23438/'85 and joint use of low-grafting rate mixture of rubber particles small and medium in size proposed in 6 Japanese Laid-open Patent Publication No. 199645/'87.
According to the methods 1 and 4, however, it is difficult to sufficiently improve planar impact strength and gloss, while the methods 2, 3, 5 and 6, being effective in improving Izod impact strength, were low in practical planar impact strength attainable.
After intensive studies for solution of the aforementioned problems about ABS resins, the present inventors have found that the planar impact strength could be improved when rubber particles small and medium in size having given graft parts were present in predetermined ratio, the effect being particularly remarkable when said medium-size rubber particles were those prepared by a given growing method, and thus arrived at the present invention.
DISCLOSURE OF THE INVENTION
The present invention relates to a resin composition excellent in impact strength comprising:
a graft copolymer (I) comprizing a rubber polymer part (A) whose volume average particle size determined by the transmission type electron microscope analysis-image analysis method (TEM method) is 250-800 nm and a graft part (a) whose volume ratio to said rubber copolymer part (A): (a)/(A) is 0.10-0.80, and
a graft copolymer (II) comprizing a rubber polymer part (B) whose volume average particle size by the TEM method is 60-160 nm and a graft part (b) whose volume ratio to said rubber copolymer part (B): (b)/(B) is 0.30-1.00, and
a copolymer (III) comprizing 15-60 mol % of
REFERENCES:
patent: 4009227 (1977-02-01), Ott
patent: 5283287 (1994-02-01), Kim
Doi Norito
Matsumoto Shigemi
Matsumura Youichi
Mishima Ikuhiro
Kanegafuchi Kagaku Kogyo & Kabushiki Kaisha
Zitomer Fred
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