Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Patent
1997-12-22
1999-11-02
Buttner, David
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
525193, 525194, C08L 2316, C08L 900
Patent
active
059772590
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a thermoplastic elastomer composition and a molded article comprising the same.
PRIOR ART
Molded articles having complicated patterns such as leather grains or stitches are used as skin materials of interior parts of automobiles, and molded articles made of compositions comprising vinyl chloride resins are widely used as the skin materials. However, the molded articles of the vinyl chloride resins generate hydrogen chloride gas and the like when they are incinerated after the use, and thus require specially designed incinerators.
To solve such problems, thermoplastic elastomer molded articles comprising an ethylene-.alpha.-olefin copolymer rubber and a polyolefin resin are proposed (EP-A-479 580 and EP-A-482 778). However, the thermoplastic elastomer molded articles are more easily whitened on bending than the vinyl chloride resin molded articles. Thus, the molded articles tend to have poor appearance since they are whitened at portions which have been bent when they are released from a mold after their production, or they are preformed in desired shapes. Furthermore, the thermoplastic elastomer molded articles doesn't have enough flexibility and poor feeling when touched.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a thermoplastic elastomer composition which provides a molded article that is not easily whitened on bending and has good flexibility.
Another object of the present invention is to provide a molded article of a thermoplastic resin composition, which is not easily whitened on bending and has good flexibility.
According to the first aspect, the present invention provides a thermoplastic elastomer composition comprising:
100 wt. parts, in total, of an ethylene-.alpha.-olefin copolymer rubber and a polyolefin resin, and
0.1 to 150 wt. parts of at least one hydrogenated diene polymer having a hydrogenation degree of at least 70% selected from the group consisting of hydrogenated conjugated diene polymers and hydrogenated products of random copolymers comprising conjugated dienes and aromatic vinyl compounds in which the content of the aromatic vinyl compound units is 25 wt. % or less, wherein said composition has a complex dynamic viscosity .eta.*(1) of 1.5.times.10.sup.5 poise or less, and a Newtonian viscosity index n of 0.67 or less.
According to the second aspect, the present invention provides a molded article comprising the above thermoplastic elastomer composition according to the present invention.
According to the third aspect, the present invention provides a molded article produced by powder molding the powder of the above thermoplastic elastomer composition according to the present invention.
According to the fourth aspect, the present invention provides a method for producing a molded article comprising powder molding the powder of the above thermoplastic elastomer composition according to the present invention.
DETAILED DESCRIPTION OF THE INVENTION
The ethylene-.alpha.-olefin copolymer rubbers contained in the thermoplastic elastomer composition of the present invention are amorphous copolymers obtained by copolymerizing ethylene and an .alpha.-olefin as essential monomers, and optionally other polymerizable monomer such as a non-conjugated diene.
Examples of the .alpha.-olefins are .alpha.-olefins having 3 to 10 carbon atoms such as propylene, 1-butene, 3-methyl-1-butene, and the like. Examples of the non-conjugated diene are those having 5 to 15 carbon atoms such as dicyclopentadiene, ethylidenenorbornene, 1,4-hexadiene, cycloocatadiene, methylenenorbornene, and the like.
Examples of the ethylene-.alpha.-olefin copolymer rubbers are ethylene-propylene copolymer rubbers, ethylene-propylene-ethylidenenorbornene copolymer rubbers (hereinafter referred to as "EPDM") and the like. Among them, EPDM is preferable since it can give a thermoplastic elastomer composition which provides molded articles having good heat resistance, tensile properties, and the like.
The ethylene-.alpha.-olefin copolyme
REFERENCES:
patent: 4745149 (1988-05-01), Eisele et al.
Database WPI, Section Ch, Week 9523, Derwent Publications Ltd., London, GB; Class A18, AN 95-175069, XP002073354 & JP 07 096 529 A (Mitsui Petrochem Ind.Co. Ltd), 1995.
Patent Abstracts of Japan, vol. 095, No. 009, Oct. 31, 1995 & JP 07 145278 A (Okamoto Ind Inc.), Jun. 6, 1995.
The Polymer Dictionary (p. 421, Asakura Shoten Ltd., 2.sup.nd edition 1989) .
Gotoh Yuji
Moritomi Satoru
Nagai Shinichiro
Nakatsuji Yoshihiro
Sugimoto Hiroyuki
Buttner David
Sumitomo Chemical Company Ltd.
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