Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
2001-11-14
2004-04-13
Seidleck, James J. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S474000
Reexamination Certificate
active
06720376
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a thermoplastic elastomer composition, particularly to a thermoplastic elastomer composition that can provide a molding superior in heat-aging resistance.
BACKGROUND ART
For the skin materials of interior parts of automobile instrumental panels, door trims and the like, soft poly(vinyl chloride) resins have heretofore been used mainly. However, from the viewpoint of seeking lightness of materials in recent years, olefinic thermoplastic elastomers has begun to be used.
In the case of passenger cars, higher heat-aging resistance has begun to be required because, though the temperature of the inside of cars shut tightly becomes considerably high especially under the blazing sun in summers, the recent inclination in the design of passenger cars is to use large-sized front glasses and this entails that the temperature of the skin of instrumental panels is elevated.
In order to improve the heat-aging resistance, usually heat stabilizers (antioxidants) are incorporated. This, however, raises the problem, causing the phenomenon called “bleed-out”, in that, depending to formulated amounts, the heat stabilizers ooze out from the inside to the surface and damage the appearance.
DISCLOSURE OF THE INVENTION
The present invention is to solve the problem as mentioned above accompanying the prior art. The first object of the present invention is to provide a thermoplastic elastomer composition that can give a molding excellent in heat-aging resistance. The second object of the present invention is to provide a thermoplastic elastomer composition that has the restrained bleed-out phenomenon.
The present invention includes the following inventions.
(1) A thermoplastic elastomer composition which comprises 10 to 60 parts by weight of a polyolefin (A), 30 to 87 parts by weight of a crosslinked rubber (B), 3 to 50 parts by weight of a softening agent (C) [the total amount of (A), (B) and (C) being 100 parts by weight] and 0.02 to 0.3 part by weight of a phenolic heat stabilizer (D) and which retains an elongation value at break by 80% or more, after aging for 500 hours in an air oven of 130° C., of the value before the aging.
(2) A thermoplastic elastomer composition as defined in the above (1), wherein the softening agent (C) is a paraffinic mineral oil.
(3) A thermoplastic elastomer composition as defined in the above (1) or (2), wherein the softening agent (C) has an aniline point of 140° C. or below and a sulfur content of 20 ppm or more.
(4) A thermoplastic elastomer composition as defined in any one of the above (1) to (3), wherein the softening agent (C) has a kinetic viscosity of 150 to 1000 cSt at 40° C.
(5) A thermoplastic elastomer composition as defined in any one of the above (1) to (4), which further contains 0.02 to 0.3 part by weight of a heat stabilizer other than the phenolic type.
(6) A thermoplastic elastomer composition as defined in the above (5), wherein the heat stabilizer other than the phenolic type is a sulfur-containing heat stabilizer.
(7) A thermoplastic elastomer composition as defined in any one of the above (1) to (6), which is produced by dynamically heat treating at least the whole of the crosslinked rubber (B) and part or the whole of the polyolefin (A) in the presence of a crosslinking agent.
(8) A thermoplastic elastomer composition as defined in any one of the above (1) to (7), wherein the crosslinked rubber (B) is at least one rubber selected from the group consisting of ethylene-&agr;-olefin-non-conjugated polyene copolymer rubbers, ethylene-&agr;-olefin copolymer rubbers, isoprene rubbers or hydrogenated products thereof, butadiene rubbers or hydrogenated products thereof, styrene-butadiene rubbers or hydrogenated products thereof, styrene-isoprene rubbers or hydrogenated products thereof, chloroprene rubbers, butyl rubbers, halogenated butyl rubbers, acrylonitrile-butadiene rubbers, chlorinated polyethylene rubbers, fluororubbers, silicone rubbers, polysulfide rubbers and urethane rubbers.
(9) A thermoplastic elastomer composition as defined in any one of the above (1) to (8), wherein the polyolefin (A) is a polymeric resin based on propylene and the crosslinked rubber (B) is an ethylene-&agr;-olefin-non-conjugated polyene copolymer rubber.
(10) A thermoplastic elastomer composition as defined in any one of the above (1) to (9), wherein the rubber is crosslinked by an organic peroxide.
(11) A thermoplastic elastomer composition as defined in any one of the above (1) to (10), which is produced by using a twin screw extruder.
(12) A method for producing a thermoplastic elastomer composition, which is characterized by dynamically heat treating 10 to 60 parts by weight of a polyolefin (A), 30 to 87 parts by weight of a rubber (B′), 3 to 50 parts by weight of a softening agent (C) [the total amount of (A), (B′) and (C) being 100 parts by weight] and 0.02 to 0.3 part by weight of a phenolic heat stabilizer (D) in the presence of a crosslinking agent.
Hereinafter the thermoplastic elastomer composition according to the present invention will be explained in detail.
The thermoplastic elastomer of the present invention is a composition including and comprising a polyolefin (olefinic resin) (A), a crosslinked rubber (B), a softening agent (C), a phenolic heat stabilizer (D) and a heat stabilizer other than the phenolic type, for example, a sulfuric stabilizer (E) incorporated where deemed necessary.
Polyolefin (Olefinic Resin) (A)
The polyolefin (olefinic resin) (A) used in the present invention usually comprises a polymeric solid product obtained by polymerizing one or more of monoolefin through a high pressure or low pressure method. Such resins include, for example, isotactic and syndiotactic polymeric resins of monoolefin. The typical resins of these are commercially available.
As suitable raw material olefins for the above-mentioned polyolefins (A), there are enumerated preferably &agr;-olefins having 2 to 20 carbon atoms, concretely, ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 2-polyene polyene copolymer rubbers, ethylene-&agr;-olefin copolymer rubbers, isoprene rubbers or hydrogenated products thereof, butadiene rubbers or hydrogenated products thereof, styrene-butadiene rubbers or hydrogenated products thereof, styrene-isoprene rubbers or hydrogenated products thereof, chloroprene rubbers, butyl rubbers, halogenated butyl rubbers, acrylonitrile-butadiene rubbers, chlorinated polyethylene rubbers, fluororubbers, silicone rubbers, polysulfide rubbers and urethane rubbers. Herein, the term “hydrogenated product” indicates a product in which the whole or part of the double bonds are saturated by hydrogen addition treatment.
Among these, ethylene-&agr;-olefin-non-conjugated polyene copolymer rubbers are favorable, and particularly favorable are ethylene-propylene-non-conjugated diene rubbers having the following properties.
Ethylene/propylene ratio: 50/50 to 90/10 (molar ratio)
Iodine value: 3 to 30 (g/100 g)
Mooney viscosity ML
1+4
(100° C.): 15 to 250
The non-conjugated dienes used for the above-mentioned ethylene-propylene-non-conjugated diene rubbers include, concretely, cyclic dienes such as dicyclopentadiene, cyclooctadiene, methylenenorbornene (for example, 5-methylene-2-norbornene), ethylidenenorbornene (for example, 5-ethylidene-2-norbornene), methyltetrahydroindene, 5-vinyl-2-norbornene, 5-isopropylidene-2-norbornene, 6-chloromethyl-5-isopropenyl-2-norbornene, norbornadiene; and chain dienes such as 1,4-hexadiene, 3-methyl-1,4-hexadiene, 4-methyl-1,4-hexadiene, 5-methyl-1,4-hexadiene, 4,5-dimethyl-1,4-hexadiene, 6-methyl-1,6-octadiene, 7-methyl-1,6-octadiene, 6-ethyl-1,6-octadiene, 6-propyl-1,6-octadiene, methyl-1-propene, 3-methyl-1-pentene, 4-methyl-1-pentene and 5-methyl-1-hexene. These olefins are used alone or in a mixture of two or more.
The polymerization mode can be either random or block mode as long as a resinous substance is obtained.
These polyolefins can be used singly or in a combination of two or more.
Among these polyolefi
Itoh Yuichi
Uchiyama Akira
Mitsui Chemicals Inc.
Rajguru Umakant
Seidleck James J.
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