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
2001-09-07
2003-03-11
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...
C525S216000, C525S232000, C525S240000
Reexamination Certificate
active
06531546
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a rubber composition comprising an ethylene/&agr;-olefin
on-conjugated diene copolymer rubber as a major component, exhibiting superior processability, such as roll processability and extrusion processability, excellent tackiness (adhesiveness), and capable of producing vulcanized rubber having excellent mechanical characteristics and low and high temperature properties.
The rubber composition of the present invention can be suitably used for a wide variety of applications such as a hose, sponge material, sealing material, electric insulating material, injection processing material, industrial rubber product, rubber material for vehicles, and the like.
2. Description of the Background Art
Conventionally, ethylene/&agr;-olefin
on-conjugated diene copolymer rubbers have more excellent weather resistance, heat resistance, and ozone resistance than diene-type rubbers due to absence of unsaturated bonds in the main chain and, therefore, are used for a wide variety of applications such as a hose, sponge material, sealing material, injection processing material, rubber material for vehicles, and the like.
The extended area of applications of such products in recent years requires a rubber material exhibiting better properties and processability in both a high temperature region and a low temperature region.
Conventionally, when using an ethylene/&agr;-olefin
on-conjugated diene copolymer rubber as a rubber material exhibiting superior processability, either a low molecular weight copolymer among the ethylene/&agr;-olefin
on-conjugated diene copolymers is used or such a copolymer rubber is used in admixture with a larger amount of process oil.
However, an ethylene/&agr;-olefin
on-conjugated diene copolymer rubber having a small molecular weight results in formed products with poor properties, particularly poor strength. Addition of a large amount of process oil to an ethylene/&agr;-olefin
on-conjugated diene copolymer rubber not only may soil a mold due to bleed-out, but also may cause vulcanization-adhesion defects, resulting in formed products with inadequate properties.
An object of the present invention is to provide a rubber composition comprising an ethylene/&agr;-olefin
on-conjugated diene copolymer rubber, exhibiting superior processability, such as roll processability and extrusion processability, producing formed products with an excellent surface, and exhibiting excellent adhesiveness.
Another object of the present invention is to provide an ethylene/&agr;-olefin
on-conjugated diene copolymer rubber composition capable of producing vulcanized rubber having excellent mechanical characteristics and superior low and high temperature properties.
SUMMARY OF THE INVENTION
As a result of extended studies, the inventors of the present invention have found that the above object can be attained if a rubber composition comprises a specific low molecular weight ethylene/&agr;-olefin
on-conjugated diene copolymer rubber and a specific high molecular weight ethylene/&agr;-olefin
on-conjugated diene copolymer rubber in combination. The inventors have further found that processability of the copolymer rubber can be improved if such a rubber composition is combined with a specific ethylene/&agr;-olefin
on-conjugated diene copolymer rubber. These findings have led to the completion of the present invention.
The above object can be achieved in the present invention by a rubber composition comprising (a) a low molecular weight copolymer rubber which is an ethylene/&agr;-olefin
on-conjugated diene copolymer rubber having a limiting viscosity [&eegr;] of 0.4-1.6 dl/g measured in decalin at 135° C., an ethylene content of 40-60 wt %, and an iodine number of 5-35 and (b) a high molecular weight copolymer rubber which is an ethylene/&agr;-olefin
on-conjugated diene copolymer rubber having a Mooney viscosity (ML
1+4
, 100° C.) of 60-150, an ethylene content of 60-80 wt %, and an iodine number of 5-35, wherein the difference between the iodine number of the low molecular weight copolymer rubber (a) and the iodine number of the high molecular weight copolymer rubber (b) is 5 or less and the ratio by weight of the low molecular weight copolymer rubber (a) and the high molecular weight copolymer rubber (b) is 50/50 to 80/20, the rubber composition having a Mooney viscosity (ML1+4, 100° C.) of 20-50.
In the above rubber composition, the difference between the iodine number of the low molecular weight copolymer rubber (a) and the iodine number of the high molecular weight copolymer rubber (b) is preferably 3 or less.
In the above rubber composition, the &agr;-olefin in the low molecular weight copolymer rubber (a) or the high molecular weight copolymer rubber (b) is preferably one or more &agr;-olefins selected from the group consisting of propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, and 1-eicosene.
In the above rubber composition, the &agr;-olefin in the low molecular weight copolymer rubber (a) or the high molecular weight copolymer rubber (b) is preferably propylene, 1-butene, or 1-octene.
In the above rubber composition, the non-conjugated diene in the low molecular weight copolymer rubber (a) or the high molecular weight copolymer rubber (b) is preferably one or more non-conjugated dienes selected from the group consisting of 5-ethylidene-2-norbornene, 5-propylidene-2-norbornene, dicyclopentadiene, 5-vinyl-2-norbornene, 5-methylene-2-norbornene, 5-isopropylidene-2-norbornene, norbornadiene, 1,4-hexadiene, 4-methyl-1,4-hexadiene, 5-methyl-1,4-hexadiene, 5-methyl-1,5-heptadiene, 6-methyl-1,5-heptadiene, 6-methyl-1,7-octadiene, and 7-methyl-1,6-octadiene.
In the above rubber composition, the non-conjugated diene in the low molecular weight copolymer rubber (a) or the high molecular weight copolymer rubber (b) is preferably 1,4-hexadiene, dicyclopentadiene, or 5-ethylidene-2-norbornene.
The above object can be achieved in the present invention by a vulcanized rubber product obtained by vulcanizing the above rubber composition using sulfur, a sulfur compound, or an organic peroxide.
In the above vulcanized rubber product, the sulfur or sulfur compound is preferably used in an amount from 0.1 to 10 parts by weight for 100 parts by weight of the copolymer rubber.
The above object can be achieved in the present invention by a rubber composition comprising 30-80 wt % of the above rubber composition and 20-70 wt % of an ethylene/&agr;-olefin
on-conjugated diene copolymer rubber (c) having a Mooney viscosity (ML
1+4
, 100° C.) of 30-90, an ethylene content of 45-60 wt %, and an iodine number of 5-35, provided the total of the rubber composition and the ethylene/&agr;-olefin
on-conjugated diene copolymer rubber (c) is 100 wt % (the ethylene/&agr;-olefin
on-conjugated diene copolymer rubber (c) is hereinafter referred to simply as “copolymer rubber (c)”).
Other objects, features and advantages of the invention will hereinafter become more readily apparent from the following description.
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patent: 0 466 380 (1991-09-01), None
patent: 0 832 926 (1998-04-01), None
K.F. Heinisch, “EPDM Rubber”, Dictionary Of Rubber, Applied Science Publishers, Ltd. pp. V, 192-193, 1974.
Martin E. Samuels, “Ethylene-Propylene Rubbers”, The Vanderbilt Rubber Handbook, R.T. Vanderbilt Company Inc., pp. 147-169, 1978.
Jacqueline I. Kroschwitz, “Ethylene-Propylene Elastomers”, Concise Encyclopedia Of Polymer Science And Engineering, John Wiley & Sons, pp. 359-362, 1990.
“Ethylene-Propylene Elastomers”, Encyclopedia Of Polymer Science And Engineering, vol. 6, John Wiley & Sons, pp.522-524 & 562, 1986.
Abe Yutaka
Nishimura Toshihiro
Oka Katsumi
Tsutsumi Fumio
JSR Corporation
Nutter Nathan M.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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