Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Patent
1997-05-07
1998-09-08
Short, Patricia A.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
525100, 525102, 525105, C08F28312, C08G 77442
Patent
active
058046550
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to silicone-modified acyrlic rubber particles, graft copolymer particles of silicon-modified acrylic rubber which are prepared by using the above-mentioned rubber particles and are excellent in impact resistance and weather resistance, and a thermoplastic resin composition which comprises the above-mentioned graft copolymer particles and a thermoplastic resin and is excellent in weather resistance and impact resistance.
BACKGROUND ART
Enhancement of impact resistance of a thermoplastic resin has been heretofore made widely by blending, to the resin, a modifier comprising graft copolymer particles containing a rubber particle component.
As the rubber particle component contained in the above-mentioned graft copolymer particles there are widely used, for example, polybutadiene rubber particles, styrene-butadiene copolymer rubber particles, acrylic rubber particles, and the like.
In order to enhance the above-mentioned impact resistance, for example, a modifier prepared by graft-copolymerizing methyl methacrylate and styrene to the above-mentioned styrene-butadiene copolymer rubber particles (so-called MBS resin), or a modifier prepared by graft-polymerizing methyl methacrylate to the above-mentioned acrylic rubber particles is commercially available as an impact modifier used for vinyl chloride resin (which include vinyl chloride homopolymer resin and a vinyl chloride copolymer resin obtained by copolymerizing vinyl chloride with not more than 50% (% by weight, hereinafter the same) of a monomer copolymerizable therewith, for example, vinyl acetate, ethylene, acrylic acid ester, vinyl bromide or two or more thereof, and further include a chlorinated polyvinyl chloride (chlorine content: 60 to 68%).
Also there is known so-called rubber reinforced resin obtained by blending, to the thermoplastic resin, graft copolymer particles as the impact modifier, which are prepared by graft-polymerizing, to the above-mentioned rubber particles, a vinyl monomer (which includes not only a vinyl monomer but also a monomer having polymerizable C.dbd.C bond, such as vinylidene monomer). As the graft copolymer particles, there are well known, for example, an impact resistance polystyrene (HIPS) prepared by graft-polymerizing styrene to polybutadiene rubber particles, an acrylonitrile/butadiene/styrene copolymer (ABS) prepared by graft-copolymerizing acrylonitrile and styrene to polybutadiene rubber particles.
The above-mentioned impact modifier obtained by using the polybutadiene rubber particles exhibits a large effect of improvement of impact resistance because its glass transition temperature (Tg) is as low as around -80.degree. C., but has a problem such that since polybutadiene has unsaturated bonds in its structure, deterioration due to oxidation is easy to occur and weather resistance is worse.
On the contrary, the impact modifier obtained by using the acrylic rubber particles has a good weather resistance, but has a drawback such that impact resistance, particularly one at a low temperature is not sufficient since the Tg is relatively high, i.e. around -50.degree. C.
In order to overcome these drawbacks, it was proposed to use graft copolymer particles of silicone rubber particles or of a composite rubber ontaining silicone rubber particles.
In case where the above-mentioned silicone rubber particles are used, weather resistance is excellent, and in addition, it can be expected that weather resistance and impact resistance are improved since the Tg is -120.degree. C. which is lower than that in case of the above-mentioned polybutadiene rubber particles.
For example, JP-A-100812/1992 discloses the use of composite rubber (graft copolymer) particles having such a structure that a polyorganosiloxane rubber component and a polyalkyl (meth)acrylate rubber component are entangled with each other so as not to be separated. Those composite rubber particles are prepared by emulsifying and dispersing a cyclic siloxane in an aqueous medium by using alkylbenzenesulfonic acid with a
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Database WPI, Section Ch, Week 9250, Derwent Publications Ltd., London, GB AN 92-410440, XP002053807, JP 04 306 251 A (Mitsubishi Rayon Co Ltd), Oct. 29, 1992 Abstract.
Hosoi Hideki
Miyatake Nobuo
Yoshino Hiroki
Kaneka Corporation
Short Patricia A.
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