Stock material or miscellaneous articles – Composite – Of addition polymer from unsaturated monomers
Reexamination Certificate
1998-09-14
2001-12-18
Copenheaver, Blaine (Department: 1773)
Stock material or miscellaneous articles
Composite
Of addition polymer from unsaturated monomers
C428S500000, C525S191000, C525S194000
Reexamination Certificate
active
06331360
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a thermoplastic elastomer composition, and a powder and a molded article of the same.
PRIOR ART
Sheet-form molded articles having complicated uneven decorations such as grains or stitches are used as skin materials of interior parts of automobiles and the like. As such molded articles, molded articles of thermoplastic elastomers are proposed as substitutes for conventional molded articles of vinyl chloride resins (see, for example, JP-A-5-001183 and JP-A-5-005050). However, the molded articles of thermoplastic elastomers have lower flexibility than those of vinyl chloride resins, and tend to be whitened when they are bent. Thus, the molded articles of the thermoplastic elastomers are easily whitened at bent portions when they are removed from a mold in the molding process for the production of molded articles or when they are preshaped before they are laminated onto substrates. Therefore, it is desired to provide molded articles of thermoplastic elastomers which are less whitened on bending.
SUMMARY OF THE INVENTION
The present inventors have made extensive study on thermoplastic elastomers which can provide molded articles which are less whitened on bending. As a result, it has been found that a thermoplastic elastomer composition comprising a polyolefin resin and a specific ethylene-&agr;-olefin copolymer rubber in a specific ratio can provide a molded article which is hardly whitened, and the present invention has been completed.
According to the first aspect, the present invention provides a thermoplastic elastomer composition comprising
(a) 100 wt. parts of a polyolefin resin,
(b) 5 to 250 wt. parts of an ethylene-&agr;-olefin copolymer rubber in which the content of the &agr;-olefin units is at least 50 wt. %, and
(c) 0 to 500 wt. parts of an ethylene-&agr;-olefin copolymer rubber in which the content of the &agr;-olefin units is less than 50 wt. %.
According to the second aspect, the present invention provides a powder comprising the above thermoplastic elastomer composition and having a sphere-converted average particle size of 1.2 mm or less and a bulk specific gravity of at least 0.38.
Such a powder is used in a powder molding method and can provide a molded article which has neither pinholes nor underfills and also good flexibility so that it is hardly whitened when it is bent.
According to the third aspect, the present invention provides a molded article comprising the above thermoplastic elastomer composition. The molded article of the present invention is hardly whitened when it is bent.
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patent: 5843577 (1998-12-01), Ouhadi et al.
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Hozumi Hidetake
Nakatsuji Yoshihiro
Sugimoto Hiroyuki
Copenheaver Blaine
Paulraj Christopher
Sumitomo Chemical Company Limited
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