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
2001-03-15
2003-09-16
Wu, David W. (Department: 1713)
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...
C524S081000, C525S232000, C525S236000, C525S237000, C525S326100
Reexamination Certificate
active
06620873
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a process for producing a rubber composition comprising an ethylene-&agr;-olefin based copolymer rubber as the rubber component and a rubber composition obtained by the process. In more particular, it relates to a process for producing a rubber composition comprising an ethylene-&agr;-olefin based copolymer rubber as the rubber component which is excellent in heat resistance and fatigue resistance as well as to a rubber composition obtained by the process.
BACKGROUND OF THE INVENTION
Previously, in the field of automobiles and industrial goods, ethylene-&agr;-olefin copolymer rubbers or ethylene-&agr;-olefin-non-conjugated diene rubbers typically represented by ethylene-propylene rubber (EPM) or ethylene-propylene-non-conjugated diene rubber (EPDM), respectively, have been in wide use by virtue of their desirable characteristic performances. In recent years, on the other hand, particularly in the automobile field, long-life automobile parts have been eagerly desired from the viewpoint of securing practically maintenance-free vehicles.
However, ethylene-&agr;-olefin copolymer rubber and ethylene-&agr;-olefin-non-conjugated diene copolymer rubber have a drawback in that they are inferior to natural rubber in reinforcing capability owing to the molecular weight and other factors, so that they are poor in fatigue resistance when subjected to repeated external force for a long time or to deformation under heavy load. Consequently, it has not been possible to use these rubbers under severe external force or severe deforming conditions.
SUMMARY OF THE INVENTION
In view of such situations, the object of this invention is to provide a process for producing a rubber composition comprising an ethylene-&agr;-olefin based copolymer rubber as the rubber component which is excellent in heat resistance and fatigue resistance as well as a rubber composition obtained by the said process.
Thus, one aspect of this invention relates to a process for producing a rubber composition comprising:
(A) an ethylene-&agr;-olefin based copolymer rubber having an intrinsic viscosity [&eegr;] of 2.0-10.0 as determined in xylene at 70° C.,
(B) a softening agent, and
(C) a filler,
which process comprises the steps of:
(I) dividing component (A) into portions (A
1
) and (A
2
), dividing component (B) into portions (B
1
) and (B
2
), dividing component (C) into portions (C
1
) and (C
2
), and kneading portions (A
1
), (B
1
) and (C
1
) together to obtain a first blend, and
(II) adding portions (A
2
), (B
2
) and (C
2
) to the first blend to obtain a second blend and kneading the second blend to obtain the rubber composition.
Another aspect of this invention relates to a rubber composition obtained by the above-mentioned process.
DETAILED DESCRIPTION OF THE INVENTION
Component (A) is an ethylene-&agr;-olefin based copolymer rubber having an intrinsic viscosity [&eegr;] of 2.0-10.0 as determined in xylene at 70° C.
The “ethylene-&agr;-olefin based copolymer rubber” herein refers to ethylene-&agr;-olefin copolymer rubber or ethylene-&agr;-olefin-non-conjugated diene copolymer rubber.
The&agr;a-olefin can be, for example, propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene and 1-decene. Particularly preferred among them is propylene. The non-conjugated dienes can be, for example, chain-like non-conjugated diene, such as 1,4-hexadiene, 1,6-octadiene, 2-methyl-1,5-hexadiene, 6-methyl-1,5-heptadiene and 7-methyl-1,6-octadiene; cyclic non-conjugated dienes, such as cyclohexadiene, dicyclopentadiene, methyltetrahydroindene, 5-vinyl-2-norbomene, 5-ethylidene-5-norbomene-2-methanol, 5-methylene-5-norbornene-2-methanol, 5-isopropylidene-5-norbomene-2-methanol, and 6-chloromethyl-5-isopropenyl-5-norbomene-2-methanol; and trienes, such as 2,3-disopropylidene-5-norbornene-2-methanol, 2-ethylidene-3-isopropylidene-5-norbomene-2-methanol, 2-propenyl-2-norbomadiene, 1,3,7-octatriene and 1,4,9-decatriene. They can be used alone or in admixture of two or more of them. Particularly preferred among them are 1,4-hexadiene, dicyclopentadiene and 5-ethylidene-2-norbornene-2-methanol. The ethylene-&agr;-olefin copolymer rubber or ethylene-&agr;-olefin-non-conjugated diene copolymer rubber can be used as oil-extended rubbers containing extending oil.
The molar ratio of ethylene to &agr;-olefin (ethylene/&agr;-olefin) in Component (A) ranges preferably 40/60-90/10. The content of diene, when it is used, is not more than 20% of the total weight of ethylene, &agr;-olefin and diene.
Component (A) has an intrinsic viscosity [&eegr;] of preferably 2.0-10.0, more preferably 2.5-5.0, as determined in xylene at 70° C. When the [&eegr;] is outside the above-mentioned range, the ultimately obtained rubber composition tends to be unsatisfactory in fatigue resistance.
Component (B) is a softening agent. The softening agent is not particularly limited and can be any softening agents which have been commonly used in the field of rubber industry, for example, petroleum-based materials, such as aromatic, naphthenic or paraffinic process oils, lubricant oils, paraffins, liquid paraffins, petroleum asphalts and vaselines; coal tars, such as coal tar and coal tar pitch; fatty oils, such as castor oil, linseed oil, rape seed oil and coconut oil; waxes, such as tall oil, factice, beeswax, carnauba wax and lanolin; and liquid diene-based polymers, such as liquid polybutadiene, modified liquid polybutadiene, liquid polyisoprene and hydrogenated liquid polyisoprene. The softening agents can be used each alone or in admixture of two or more of them.
Component (C) is a filler. The filler is not particularly restricted and can be any fillers which have been commonly used in the field of rubber industry, for example, carbon black; inorganic fillers, such as hydrated silica, anhydrous silica, talc, calcium carbonate, clay, titanium oxide, magnesium carbonate, magnesium oxide and aluminum hydroxide; and organic fillers, such as high styrene resin, coumarone-indene resin, phenol resin, lignin resin, modified melamine resin and petroleum resin. The fillers can be used either singly or in a combination of two or more thereof. From the viewpoint of obtaining good fatigue resistance, the use of carbon black is preferred. The carbon black include, for example, HAF, MAF, FEF and SRF black. Any of them can be used regardless of their reinforcing properties. The carbon black can be used each alone or in combination of two more kinds thereof, e.g., HAF together with MAF.
The process of this invention is a process for producing a rubber composition which comprises the following step (I) and step (II).
Step (I) is a step of dividing component (A) into portions (A
1
) and (A
2
), dividing component (B) into portions (B
1
) and (B
2
), dividing component (C) into portions (C
1
) and (C
2
), and kneading portions (A
1
), (B
1
) and (C
1
) together to obtain a first blend.
The proportion of portion (A
1
) used in step (I) ranges preferably 2-80% of component (A). When the proportion is outside the above-mentioned range, the rubber composition ultimately obtained is unsatisfactory with respect to fatigue resistance in some cases. The proportion of portion (B
1
) used in step (I) ranges preferably 2-95% of component (B). When the proportion is outside the above-mentioned range, the rubber composition ultimately obtained is unsatisfactory with respect to fatigue resistance in some cases. The proportion of portion (Cl) used in step (I) ranges preferably 2-60% of component (C). When the proportion is outside the above-mentioned range, the rubber composition ultimately obtained is unsatisfactory with respect to fatigue resistance in some cases.
The kneading can be conducted with an apparatus conventionally used in the rubber industry, for example, an open roll, internal kneader and extruder. The conditions for kneading can also be conventional ones and are not particularly limited.
Step (II) is a step of adding portions (A
2
), (B
2
) and (C
2
) to the first blend to obtain a second b
Nakano Sadayuki
Nishida Takashi
Hu Henry S.
Sughrue & Mion, PLLC
Sumitomo Chemical Company Limited
Wu David W.
LandOfFree
Process for producing rubber composition and rubber composition does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process for producing rubber composition and rubber composition, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for producing rubber composition and rubber composition will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3074554