Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Cellular products or processes of preparing a cellular...
Reexamination Certificate
2001-10-24
2003-04-01
Foelak, Morton (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Cellular products or processes of preparing a cellular...
C521S085000, C521S094000, C521S135000, C521S178000, C521S149000
Reexamination Certificate
active
06541529
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a polymer composition for powder foam molding, powder thereof, a foam obtained therefrom, a process for producing the foam, and a molded article comprising the foam. More specifically, the present invention relates to a polymer composition containing a polymer having an epoxy group as a polymer component, and being excellent in storage stability in an uncrosslinked state, capable of being crosslinked and foamed in a short period of time and capable of providing a foam having a small compression set, an excellent surface texture and little skin lack of hiding, powder thereof, a foam obtained from the composition, a process for producing the foam and a molded article comprising the foam.
PRIOR ART
Automobile interior parts such as instrument panels, head rests, arm rests, and door trims have remarkably shifted from conventional hard types to soft types. These parts are composed of an embossed surface layer and a foam layer as a cushioning layer. As a material of the foam layer, a crosslinkable foamable polymer composition is used, but it has a drawback in that the crosslinking thereof is promoted while being stored and properties of the composition change, therefore, there is a problem in that it is difficult to obtain stably compositions with desired properties.
Besides, in the production of automobile interior parts, after an article composed of a surface layer and a foam layer, integrally molded is formed by powder slush molding, a post-processing is required for applying a resin to a surface on the foam layer side by injection molding so as to form a reinforcing layer. Here since a high temperature and a high pressure (a temperature of approximately 100° C. to 280° C., and a pressure of approximately 15 Kgf/cm
2
to 600 Kgf/cm
2
) are applied to the foam layer side, a problem arises in that the foam layer is destroyed and the function as a cushioning member is significantly deteriorated.
At the present time, there has not been found a method which can stably obtain a foam having a smooth and excellent surface texture, and further a small compression set enough to resist under a high temperature and a high pressure during infection molding.
DISCLOSURE OF THE INVENTION
Under these circumstance, an object of the present invention is to provide a polymer composition containing a polymer having an epoxy group as a polymer component, excellent in storage stability in an uncrosslinked state, capable of being crosslinked and foamed in a short period of time, and also capable of providing a foam having a small compression set, an excellent surface texture and little surface lack of hiding, further, powder of the composition, a foam obtained from the composition, a method for producing a foam, and a molded article comprising the foam.
Namely, the present invention relates to a polymer composition for powder foam molding which comprises (A) a polymer having an epoxy group, (B) a peroxide having a temperature for obtaining a half-life of 10 hours of 100° C. or higher, (C) at least one of quaternary ammonium salts and quaternary phosphonium salts, and (D) a thermally decomposable foaming agent.
Further, the present invention relates to a powder comprising the polymer composition, a foam obtained by crosslinking and foaming the powder, and a method for producing the foam.
Furthermore, the present invention relates to a two-layer molded article obtained by laminating a non-foam layer of a thermoplastic elastomer composition or a vinyl-chloride-based resin composition on a foam layer made of the foregoing foam, and relates to a multi-layer molded article obtained by laminating a protective layer of a thermoplastic resin composition or a thermoplastic elastomer composition on the foam layer side of the foregoing two-layer molded article.
BEST MODE FOR CARRYING OUT THE INVENTION
In the present invention, the polymer (A) having an epoxy group is not particularly limited so far as it is a polymer containing an epoxy group used as a crosslinking point, and any one used for producing a crosslinked foam can be used.
A preferable epoxy group having polymer (A) is described below. A copolymer of a monomer containing an epoxy group used as a crosslinking point with a monomer copolymerizable therewith is preferably.
As the epoxy group-containing monomer, unsaturated glycidyl carboxylates such as glycidyl acrylate, glycidyl methacrylate, glycidyl itaconate and the like; and unsaturated glycidyl ethers such as vinyl glycidyl ether, allyl glycidyl ether, methacryl glycidyl ether and the like. Among these, glycidyl methacrylate and glycidyl acrylate are preferable.
As the monomer copolymerizable with the epoxy group-containing monomer, there are listed vinyl monomers having no epoxy group such as vinyl carboxylates (e.g. vinyl acetate, vinyl propionate), vinyl ketones (e.g. methyl vinyl ketone, ethyl vinyl ketone), and vinyl aromatic compounds (e.g. styrene, &agr;-methyl styrene, vinyl toluene), and esters of unsaturated carboxylic acid (e.g. methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, n-octyl acrylate, methoxy methyl acrylate, methoxy ethyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate); &agr;-olefins such as ethylene, propylene, 1-butene and the like; and dienes such as butadiene and the like. These monomers may be used alone or in combination of two or more so as to be copolymerized with the epoxy group-containing monomer.
Examples of the epoxy group-containing polymer (A) includes: ethylene-vinyl acetate-epoxy group-containing monomer copolymers (for example, ethylene-vinyl acetate-glycidyl acrylate copolymer and ethylene-vinyl acetate-glycidyl methacrylate copolymer); ethylene-(meth)acrylate-epoxy group-containing monomer copolymers (for example, ethylene-methyl acrylate-glycidyl acrylate copolymer, ethylene-methyl methacrylate-glycidyl acrylate copolymer, ethylene-methyl acrylate-glycidyl methacrylate copolymer, and ethylene-methyl methacrylate-glycidyl methacrylate copolymer); ethylene-vinyl acetate-(meth)acrylate-epoxy group-containing monomer copolymers (for example, ethylene-vinyl acetate-methyl acrylate-glycidyl acrylate copolymer, and ethylene-vinyl acetate-methyl methacrylate-glycidyl acrylate copolymer); ethylene-propylene-epoxy group-containing monomer copolymers (for example, ethylene-propylene-glycidyl methacrylate copolymer, and ethylene-propylene-glycidyl actylate copolymer); (meth)acrylate-acrylonitrile-epoxy group-containing monomer copolymers (for example, acrylonitrile-methyl acrylate-glycidyl methacrylate copolymer, and acrylonitrile-methyl methacrylate-glycidyl methacrylate copolymer), ethylene-butadiene-epoxy-group containing monomer copoblymers (for example, ethylene-butadiene-glycidyl methacrylate copolymer, and ethylene-butadiene-glycidyl acrylate copolymer); and styrene-butadiene-epoxy group-containing monomer copolymers (for example, styrene-butadiene-glycidyl methacrylate copolymer, and styrene-butadiene-glycidyl acrylate); and the like.
The epoxy group-containing copolymer (A) preferably contains 0.1 to 35 wt % of epoxy group-containing monomer units functioning as crosslinking points, in the total of monomer units. More preferably, the copolymer (A) is obtained by copolymerizing 0.1 to 35 wt % (further preferably, 1 to 30 wt %) of the epoxy group-containing monomer, 30 to 99.8 wt % (further preferably, 40 to 98 wt %) of ethylene, &agr;-olefin or diene, and 0.1 to 35 wt % (further more preferably, 1 to 25 wt %) of a vinyl monomer containing no epoxy group, or alternatively, 0.1 to 35 wt % (further preferably, 1 to 30 wt %) of the epoxy group-containing monomer, and 65 to 99.9 wt % (further preferably, 70 to 99 wt %) of the vinyl monomer containing no epoxy group, by a known polymerizing method such as solution polymerization, emulsion polymerization, suspension polymerization, slurry polymerization, or gas phase polymerization.
The peroxide (B) used in the present invention is a peroxide which has a temperature for obtaining a half-life of 10 hours of not lower than 100° C. W
Iketani Kohichi
Nakatsuji Yoshihiro
Ohtani Kohsuke
Birch & Stewart Kolasch & Birch, LLP
Foelak Morton
Sumitomo Chemical Company Limited
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