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
2002-11-14
2004-10-12
Nutter, Nathan M. (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...
C525S240000
Reexamination Certificate
active
06803418
ABSTRACT:
This application is the national phase under 35 U.S.C. § 371 of PCT International Application No. PCT/JP02/02357 which has an International filing date of Mar. 13, 2002, which designated the United States of America.
TECHNICAL FIELD
The present invention relates to an olefinic thermoplastic elastomer composition. More particularly, the present invention relates to an olefinic thermoplastic elastomer composition comprising a polypropylene resin and an &agr;-olefinic copolymer which composition has excellent rubbery elasticity.
BACKGROUND ART
There have heretofore been employed a variety of materials for parts or portions requiring rubbery elasticity in the field of automobile parts, industrial machinery parts, electric and electronic parts, constructional materials and the like. These materials include, for example, vulcanized rubber. Usually, the vulcanized rubber is produced via the vulcanization process wherein a rubber is kneaded with crosslinking agents, crosslinking aids, additives and subsidiary materials to prepare an unvulcanized rubber compound and then is vulcanized with heat. Because of this, it poses a problem that the process is complicated and costs much. Further, the vulcanized rubber cannot be put to recycled use because it is a thermosetting rubber.
Meanwhile, as a material not requiring the vulcanization process but possessing rubber-resembling performances, there is named vinyl chloride resin. Its use, however, is limited since it is inferior in rubbery elasticity to the vulcanized rubber.
Further, as a high molecular weight material which is plasticized at high temperatures and can be molded like plastics and which has rubbery elasticity at ordinary temperatures, there is known a thermoplastic elastomer. As an olefinic thermoplastic elastomer there is known a dynamically crosslinked product of polypropylene and ethylene-&agr;-olefinic copolymer. In this case, too, the dynamic crosslinking process is necessary, thus raising the same problem as mentioned above.
DISCLOSURE OF THE INVENTION
The object of the present invention, which is aimed at solving the problem mentioned above, is to provide an olefinic thermoplastic elastomer composition which can be produced simply by one process in the absence of a crosslinking agent, and with low cost, and which is excellent in rubbery elasticity and in addition easy to be put for recycling.
The present invention includes the following inventions.
(1) An olefinic thermoplastic elastomer composition which is obtainable by dynamically heat treating 5 to 50 parts by weight of a polypropylene resin (A) and 50 to 95 parts by weight of an &agr;-olefinic copolymer (B) having a Mooney viscosity ML
1+4
(100° C.) of 60 to 250 [the total amount of (A) and (B) being 100 parts by weight] in the absence of a crosslinking agent wherein the glass transition temperature (Tg) in dynamic visco-elasticity measurement derived from the polypropylene resin (A) in the elastomer composition is lower than the glass transition temperature (Tg) of the polypropylene resin (A), and wherein the &agr;-olefinic copolymer (B) is at least one of &agr;-olefinic copolymers selected from the following (b-1) and (b-2):
(b-1) ethylene-&agr;-olefinic copolymers which have an ethylene content of 51 to 60 mol % to the total amount of the copolymer-constituting ethylene and &agr;-olefin other than ethylene,
(b-2) propylene-&agr;-olefinic copolymers which have a propylene content of 60 to 90 mol % to the total amount of the copolymer-constituting propylene and &agr;-olefin other than propylene.
(2) An olefinic thermoplastic elastomer composition according to the above (1), wherein the &agr;-olefin other than ethylene that constitutes the ethylene-&agr;-olefinic copolymers of (b-1) is 1-butene and/or 1-octene.
(3) An olefinic thermoplastic elastomer composition according to the above (1), wherein the &agr;-olefin other than propylene that constitutes the propylene-&agr;-olefinic copolymers of (b-2) is ethylene and/or 1-butene.
(4) An olefinic thermoplastic elastomer composition according to any one of the above (1) to (3), which contains 5 to 100 parts by weight of a mineral oil type softening agent to the total 100 parts by weight of the polypropylene resin (A) of 5 to 50 parts by weight and the &agr;-olefinic copolymer (B) of 50 to 95 parts by weight that has a Mooney viscosity ML
1+4
(100° C.) of 60 to 250 [the total amount of (A) and (B) being 100 parts by weight].
The olefinic thermoplastic elastomer composition of the present invention comprises a polypropylene resin (A) and an &agr;-olefinic copolymer (B) having a Mooney viscosity ML
1+4
(100° C.) of 60 to 250.
<<Polypropylene Resin (A)>>
As the polypropylene resin (A) employed in the present invention, known polypropylene resins can be used without limitation. Examples thereof are the following polypropylene resins.
1) Propylene homopolymer
2) Random copolymer comprising propylene of 90 or more mol % and other &agr;-olefin of 10 or less mol % (propylene-&agr;-olefin random copolymer)
3) Block copolymer comprising propylene of 70 or more mol % and other &agr;-olefin of 30 or less mol % (propylene-&agr;-olefin block copolymer)
The above-mentioned other &agr;-olefin to be copolymerized with propylene includes, concretely, &agr;-olefins having 2 to 20, preferably 2 to 8 carbon atoms, such as ethylene, 1-butene, 4-methyl-1-pentene, 1-hexene and 1-octene.
One preferred as the polypropylene resin (A) is a propylene homopolymer of the above 1) and a propylene-&agr;-olefin random copolymer of the above 2). Particularly preferred is that having a MFR (ASTM D 1238, 230° C., 2.16 kg load) of 0.1 to 50 g/10 min.
The polypropylene resin (A) can be used alone or in a combination of two or more.
The content of the polypropylene resin (A) in the olefinic thermoplastic elastomer composition of the invention is 5 to 50 parts by weight, preferably 5 to 45 parts by weight, more preferably 5 to 40 parts by weight to the total 100 parts by weight of the polypropylene resin (A) and the &agr;-olefinic copolymer (B) having a Mooney viscosity ML
1+4
(100° C.) of 60 to 250.
When the content of the polypropylene resin (A) is within the above range, there can be obtained an olefinic thermoplastic elastomer composition which has good rubbery elasticity and gives good appearance with scarce rough surfaces and less adhesiveness.
<<&agr;-olefinic copolymer (B) >>
The &agr;-olefinic copolymer (B) used in the present invention is one that has a Mooney viscosity ML
1+4
(100° C.) of 60 to 250, preferably 95 to 200, and more preferably 95 to 180.
The above &agr;-olefinic copolymer (B) is at least one &agr;-olefinic copolymer rubber selected from the following (b-1) and (b-2).
(b-1) ethylene-&agr;-olefinic copolymer which has an ethylene content of 51 to 60 mol % to the total amount of the copolymer-constituting ethylene and &agr;-olefin other than ethylene,
(b-2) propylene-&agr;-olefinic copolymer which has a propylene content of 60 to 90 mol % to the total amount of the copolymer-constituting propylene and &agr;-olefin other than propylene.
The above &agr;-olefinic copolymers, (b-1) and (b-2), may further have a monomer other than &agr;-olefin in a copolymerised form. As the monomer other than &agr;-olefin, non-conjugated polyenes are enumerated. The &agr;-olefinic copolymer (B) may be a random copolymer or a block copolymer.
The above-mentioned &agr;-olefin includes, concretely, ethylene, propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene and 1-octene. The &agr;-olefin can be used alone or in a combination of two or more.
The &agr;-olefin constituting the above ethylene-&agr;-olefinic copolymer (b-1) is preferably one having 3 to 10 carbon atoms, more preferably 4 to 10 carbon atoms. The &agr;-olefin constituting the above propylene-&agr;-olefinic copolymer (b-2) is preferably one having 2 to 10 carbon atoms other than propylene.
The above non-conjugated polyene includes, for example, dicyclopenetadiene, 1,4-hexadiene, cyclooctadiene, methylenenorbornene and et
Itou Yuichi
Kobayashi Kyoko
Onogi Takayuki
Uchiyama Akira
Birch & Stewart Kolasch & Birch, LLP
Mitsui Chemicals Inc.
Nutter Nathan M.
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