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
1998-11-03
2001-08-28
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...
C526S348700, C524S579000, C525S067000, C525S064000, C525S066000, C525S078000, C525S070000
Reexamination Certificate
active
06281297
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to isobutylene rubber particles, isobutylene rubber-containing graft copolymer particles and a resin composition. More particularly the present invention relates to isobutylene rubber particles and isobutylene-based graft copolymer particles, which are useful as an impact resistant resin or an impact modifier having excellent weatherability and heat stability, and further to a thermoplastic resin composition containing these particles which exhibits a high impact resistance with maintaining properties such as weatherability and thermal stability and is suitable for production of molded articles such as sheet and film.
Impact modifiers have been used for imparting an impact resistance to various resins. Various impact modifiers have been proposed, and a core-shell graft copolymer prepared by graft-polymerizing a vinyl monomer (which forms a shell layer) onto a rubber-containing crosslinked particles (which forms a core layer) has been industrially widely used as an impact modifier. It has been recognized that the rubber component of the core layer serves to improve the impact resistance of thermoplastic resins, and the vinyl polymer of the shell layer serves to have a compatibility (namely dispersibility and adhesion property) with various resins. For example, as an impact modifier is well known a graft copolymer of a polybutadiene rubber and a vinyl monomer graft-polymerized onto the rubber. However, since a polybutadiene rubber contains unsaturated bonds and accordingly is thermally unstable, such an impact modifier having excellent thermal stability and weatherability has not been obtained.
A graft copolymer prepared by graft-polymerizing a vinyl monomer onto an acrylic rubber is also known as an impact modifier. An acrylic rubber is excellent in thermal stability and weatherability, but it has a relatively high Tg (glass transition temperature) and therefore the graft copolymer does not have a significant effect of improving impact resistance.
An impact modifier having a low Tg and being excellent in thermal stability and weatherability is known from JP-A-60-252613 and JP-A-2-8209, which disclose a graft copolymer prepared by graft-polymerizing a vinyl monomer onto a polyorganosiloxane rubber (silicone rubber). This impact modifier has, to some degree, the effect of improving impact resistance, but more improvement has been demanded. Also, this impact modifier deteriorates the processability and surface gloss of thermoplastic resins incorporated therewith.
Accordingly, an object of the present invention is to provide an impact modifier which is superior in weatherability and thermal stability and can improve the impact resistance of various thermoplastic resins without substantially lowering the processability and surface gloss.
A further object of the present invention is to provide rubber particles or rubber-containing graft copolymer particles which are useful as such an impact modifier.
Another object of the present invention is to provide a thermoplastic resin composition which is remarkably improved in impact resistance without substantially lowering the properties that the thermoplastic resins originally possess, such as excellent weatherability, heat stability and processability.
These and other objects of the present invention will become apparent from the description hereinafter.
SUMMARY OF THE INVENTION
It has been found that rubber particles comprising an isobutylene polymer and graft copolymer particles prepared by graft-polymerizing a vinyl monomer onto the isobutylene rubber particles are useful as an impact modifier and can improve the impact resistance of thermoplastic and thermosetting resins without substantially lowering the processability and surface gloss of the resins, thus providing resin compositions having a remarkably improved impact resistance and excellent processability, weatherability, thermal stability, surface gloss and the like.
In accordance with the present invention, there is provided isobutylene rubber particles comprising an isobutylene polymer.
The isobutylene polymer may contain a crosslinking agent, a graftlinking agent or a reactive functional group.
The present invention also provides particles of a graft copolymer of the above isobutylene rubber and a vinyl monomer graft-polymerized onto particles of the isobutylene rubber.
Further, the present invention provides a resin composition comprising 99 to 1 parts by weight of a thermoplastic resin and 1 to 99 parts by weight of at least one of the isobutylene rubber particles and the graft copolymer particles mentioned above.
DETAILED DESCRIPTION
The isobutylene polymer which constitutes the isobutylene rubber particles of the present invention can be prepared from a known isobutylene polymer and optionally a crosslinking agent and/or a graftlinking agent, for example, by finely dividing a raw material isobutylene polymer and subjecting the resulting isobutylene polymer particles to a crosslinking reaction of the isobutylene polymer.
The isobutylene polymer is a polymer which comprises at least 50% by weight, preferably at least 70% by weight, more preferably from 80 to 99% by weight, of units derived from isobutylene, and preferably which contains at least one functional group at its molecular end and/or in its molecular chain, e.g., a halogen-containing group, a radical-reactive unsaturated group or a silicon-containing group. The other units than the isobutylene unit, which constitute the isobutylene polymer, include, for instance, a unit derived from an initiator used when preparing the isobutylene polymer, a unit derived from a cationically polymerizable monomer which is used in the preparation of the isobutylene polymer as occasion demands, a unit derived from the reactive functional group introduced into the molecular end and/or the molecular chain of the isobutylene polymer, and the like.
Examples of the cationically polymerizable monomer which may be used in the preparation of the isobutylene polymer are, for instance, an aromatic alkenyl compound such as styrene, &agr;-methylstyrene or p-methylstyrene, vinyl ether, indene, vinyl carbazole and the like.
Examples of the reactive functional group which can be present in the molecular chain end(s) and/or molecular chain of the isobutylene polymer are, for instance, an unsaturated double bond derived from a conjugated diene monomer, a functional group represented by the formula (I):
—R—X (I)
wherein R is a single bond or a divalent hydrocarbon group having 1 to 20 carbon atoms, and X is a halogen atom, vinyl group, allyl group, isopropenyl group, allyloxy group, acryloyl group, methacryloyl group, epoxy group, amino group, cyano group, isocyano group, cyanate group, isocyanate group, carboxyl group, acid anhydride residue, hydroxyl group, mercapto group or a silicon-containing group represented by the formula:
wherein R
1
and R
2
are individually a hydrocarbon group having 1 to 20 carbon atoms or a triorganosiloxy group, Y
1
and Y
2
are individually hydrogen atom, hydroxyl group or a hydrolyzable group, a is 0 or an integer of 1 to 3, b is 0 or an integer of 1 to 2, and n is 0 or an integer of 1 to 18; provided that each of R
1
, R
2
, Y
1
and Y
2
may be the same or different when each group exists two or more times. Allyl group and silicon-containing group are preferable as the group X. The hydrolyzable group includes, for instance, alkoxyl, acyloyloxy, ketoximate, amino, amido, aminoxy, mercapto and alkenyloxy groups.
Examples of the isobutylene polymer used in the preparation of the isobutylene rubber particles are, for instance, a copolymer comprising units derived from isobutylene monomer and units derived from isoprene monomer, e.g., at most 5% by weight of isoprene units, which is generally known as so-called “butyl rubber” and is commercially available, e.g., JSR Butyl 268 (available from Japan Synthetic Rubber Co., Ltd.), KALAR5263 and KALENE800 (both available from HARDMAN INCORPORATED); a low molecular weight polyisobutylene oil having an avera
Aoyama Taizo
Kimura Katsuhiko
Armstrong Westerman Hattori McLeland & Naughton LLP
Gorr Rachel
Kaneka Corporation
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