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
1998-11-04
2001-03-13
Gorr, Rachel (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S100000, C525S101000, C525S104000, C525S106000
Reexamination Certificate
active
06201064
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to crosslinked rubber particles, raft copolymer particles containing the crosslinked rubber particles and thermoplastic resin compositions containing these particles. More particularly, the invention relates to crosslinked rubber particles and graft copolymer particles, which can be used as impact resistant resins having excellent weatherability and heat stability or as impact modifiers, and to thermoplastic resin compositions containing these particles.
Crosslinked rubber particles and graft copolymer particles wherein vinyl monomers are graft-polymerized onto the crosslinked rubber particles, have been widely used as impact resistant resins or as impact modifiers.
As the impact resistant resins, there are well known, for example, a high impact polystyrene (HIPS) obtained by graft-polymerizing styrene onto polybutadiene particles, and an acrylonitrile-butadiene-styrene copolymer (ABS) obtained by graft-polymerizing acrylonitrile and styrene onto polybutadiene particles.
Known also as the impact modifier are an impact modifier (MBS resin) obtained by graft-polymerizing methyl methacrylate and styrene onto polybutadiene rubber particles or styrene-butadiene copolymer rubber particles, and a weathering resistant impact modifier obtained by graft-polymerizing methyl methacrylate onto acrylic rubber particles.
The reason why the crosslinked rubber particles as mentioned above have been widely used as an impact resistant resin or an impact modifier is that even if they pass through a molten state during molding processing, they can maintain the particle shape and therefore are easy to exhibit properties as designed. The above-mentioned impact modifiers obtained by using polybutadiene rubber particles have a high effect of improving impact resistance because the glass transition temperature (Tg) of polybutadiene is low. However, these modifiers have the problem of being thermally unstable and poor in weatherability because they have unsaturated bonds in their structure.
On the other hand, the above-mentioned impact modifier obtained by using acrylic rubber particles is superior in weatherability, but the effect of improving impact resistance is not so good because the Tg is higher than polybutadiene.
For the purpose of improving the above-mentioned defects, an impact modifier using particles of a polyorganosiloxane (silicone) rubber which has a lower Tg and an excellent weatherability, is proposed. For example, Japanese Patent Publication Kokai No. 60-252613 (Japanese Patent Publication Kokoku No. 6-29303) discloses a graft polymerization product of a vinyl monomer onto silicone rubber particles, and Japanese Patent Publication Kokai No. 64-6012 and Japanese Patent Publication Kokai No. 4-100812 disclose a graft polymerization product of a vinyl monomer onto a composite rubber composed of a polyorganosiloxane rubber component and a polyalkyl (meth)acrylate rubber component.
However, even such impact modifiers are not always satisfactory in impact resistance, particularly in low temperature impact resistance, so further improvement has been desired.
An object of the present invention is to provide crosslinked rubber particles and graft copolymer particles containing the crosslinked rubber particles, which can be used as an impact resistant resin or impact modifier having a remarkably improved impact resistance, particularly low temperature impact resistance.
SUMMARY OF THE INVENTION
As a result of making an intensive study in view of such circumstances, the present inventors have found that crosslinked rubber particles comprising an isobutylene polymer component and an organosiloxane polymer component or comprising an isobutylene polymer component, an organosiloxane polymer component and a vinyl polymer component, and graft copolymer particles which are prepared by graft-polymerizing at least one vinyl monomer onto such crosslinked rubber particles, are suitable as an impact modifier which can improve the impact resistance of various kinds of resins without substantially deteriorating the weatherability of these resins.
Thus, the present invention provides crosslinked rubber particles comprising an isobutylene polymer component and an organosiloxane polymer component.
The present invention also provides crosslinked rubber particles comprising an isobutylene polymer component, an organosiloxane polymer component and a vinyl polymer component.
Further, the present invention provides graft copolymer particles characterized in that at least one vinyl monomer is graft-polymerized onto crosslinked rubber particles comprising an isobutylene polymer component and an organosiloxane polymer component.
Still further, the present invention provides graft copolymer particles characterized in that at least one vinyl monomer is graft-polymerized onto crosslinked rubber particles comprising an isobutylene polymer component, an organosiloxane polymer component and a vinyl polymer component.
Also, the present invention provides a thermoplastic resin composition comprising at least one of a crosslinked rubber comprising an isobutylene polymer component and an organosiloxane polymer component, and a graft copolymer comprising a vinyl monomer graft-polymerized onto said crosslinked rubber, and a thermoplastic resin.
Further, the present invention provides a thermoplastic resin composition comprising at least one of a crosslinked rubber comprising an isobutylene polymer component, an organosiloxane polymer component and a vinyl polymer component, and a graft copolymer comprising a vinyl monomer graft-polymerized onto said crosslinked rubber, and a thermoplastic resin.
DETAILED DESCRIPTION
The crosslinked rubber particles of the present invention comprise an isobutylene polymer component and an organosiloxane polymer component, or comprise an isobutylene polymer component, an organosiloxane polymer component and a vinyl polymer component.
Inclusion of the isobutylene polymer component and the organosiloxane polymer component exhibits an excellent effect on improvement in impact resistance, particularly in low temperature impact resistance, as compared with conventional impact modifiers. Further, the cost can be reduced by inclusion of the vinyl polymer component without impairing the effects produced by inclusion of the isobutylene polymer component and the organosiloxane polymer component.
On the other hand, the graft copolymer particles of the present invention comprise at least one vinyl monomer graft-polymerized onto the above-mentioned crosslinked rubber particles. By forming the above-mentioned crosslinked rubber particles to graft copolymer particles, the crosslinked rubber particles themselves are enabled to use as an impact resistant resin and, when used as an impact modifier, the compatibility with thermoplastic resins to be incorporated therewith, dispersibility and adhesion property are enhanced.
The unit particle which constitutes the crosslinked rubber particles of the present invention includes (A) a particle wherein the isobutylene polymer component, the organosiloxane polymer component and the vinyl polymer component are present together in a single particle, (B-1) a particle wherein the isobutylene polymer component and the organosiloxane polymer component are present together in a single particle, (B-2) a particle wherein the isobutylene polymer component and the vinyl polymer component are present together in a single particle, (B-3) a particle wherein the organosiloxane polymer component and the vinyl polymer component are present together in a single particle, (C-1) a particle wherein the isobutylene polymer component is present alone in a single particle, (C-2) a particle wherein the organosiloxane polymer component is present alone in a single particle, and (C-3) a particle wherein the vinyl polymer component is present alone in a single particle.
Of these, in the unit particles (A), (B-1), (B-2) and (B-3) a plurality of polymer components are present in a single particle, but the state thereof in the particle is not particu
Aoyama Taizo
Kimura Katsuhiko
Armstrong Westerman Hattori McLeland & Naughton LLP
Gorr Rachel
Kaneka Corporation
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