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
1998-10-27
2001-01-30
Dawson, Robert (Department: 1712)
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...
C524S261000, C524S266000, C524S267000, C524S268000, C524S505000, C524S506000, C036S087000, C036S03200A, C036S03400R, C138SDIG007, C198S957000, C428S447000
Reexamination Certificate
active
06180703
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a rubber composition, more specifically relates to a rubber composition superior in the properties required for applications such as footwear, conveyor belt covers, rolls, hoses, cables, rubberized fabrics, and grips, depending upon those applications and relates to footwear, conveyor belt covers, rolls, hoses, cables, rubberized fabrics, and grips which are formed by such a rubber composition in whole or part.
BACKGROUND ART
In recent years, various processed products formed from rubber or elastomers have been used in a wide variety of fields. These processed products use, as the starting materials, rubber compositions which are comprised mainly of rubber or elastomers and secondarily contain various types of fillers, additives, coloring agents, reinforcing agents, etc. so as to both secure the inherent properties of the rubber or elastomer and also impart or improve various properties required for the specific applications. In general, a rubber or elastomer alone cannot give the required reinforcement, and therefore, carbon black is compounded or formulated as a filler. However, silica etc. is sometimes compounded, together with the carbon black or in place of the carbon black, when the rubber product required is not black. For example, in the applications such as footwear, conveyor belt covers, rolls, hoses, cables, rubberized fabrics, grips, various colors are required, depending upon the applications.
However, rubber compositions containing silica, suffer from phenomena such as the increase in the viscosity, the scorching, the delayed vulcanization, when unvulcanized, which cause inferior processability or poor productivity. These unique phenomena in rubber compositions containing silica are believed to be due to the silanol groups present on the silica surface. That is, the increase in the viscosity is due to the cohesion of the silanol groups, which forms structural body in the rubber composition, whereby the viscosity is increased, the vulcanization accelerator etc. are adsorbed by the polarity of the silanol groups and, as a result, the vulcanization reaction is delayed, the performance in mixing is decreased due to the insufficient compatibility with the nonpolar rubber and, as a result, the processability of the unvulcanized rubber composition is decreased.
Further, silane coupling agents are often used together with rubber compositions containing silica. However, silanol groups are also present in the internal cavities of the silica particles. These silanol groups are reacted with the silane coupling agent to cause a loss of the silane coupling agent and, as a result, the reinforcing effect is decreased. Therefore, there was the problem that a large amount of silane coupling agent had to be compounded.
Various methods have been proposed in the past to solve these problems unique to rubber compositions containing silica. For example, methods have been proposed of adding a polar substance such as diethylene glycol or a fatty acid (see
Rubber Industry Handbook
, 4th edition;
Tire Technology International
1995, p. 107 to 108; JP-A-6-248116, etc.). However, according to these methods, when the polar compounding agent such as diethylene glycol is added to the rubber composition, the adsorbing phenomenon of polar compounding agents such as vulcanization accelerator is prevented to a certain extent, but they cannot completely prevent it. They cannot prevent substances chemically bonding with silica such as the silane coupling agent from bonding in the internal cavities of the silica and, therefore, cannot be said to be methods which can be fully applied in practice to completely resolve all problems.
Further, elimination of these problems inherent to rubber compositions containing silica and the realization of excellent properties in such rubber compositions depending upon the applications of the final products have been sought. For example, in rubber compositions used for the soles of footwear or portions of boots etc. exposed to harsh wear, a superior abrasion resistance of the vulcanizate is sought. Further, in rubber covers of conveyor belts, since abrasion occurs due to the carrying of the transported loads and cracks occur due to the flexing at the pulley portions, a superior abrasion resistance and crack resistance are sought. In rubber compositions used for rolls, due to the abrasion caused by carrying the transported iron metal, paper, etc. and the load due to the transported products, a superior abrasion resistance and bondability with iron metal of the vulcanizate are sought. In rubber compositions used for hoses, since the hoses expand due to the water pressure, oil pressure, etc. and the hoses contact each other or other objects, a superior modulus and abrasion resistance are sought. In rubber compositions used for coverings of cables, considering the lifetime of the products, a superior abrasion resistance is sought. Further, in rubber compositions used for rubberized fabric, in recent years abrasion resistance has been increasingly demanded even for rubberized clothing such as boat parkers. Further, even in the grips attached to the gripping portions of equipment or parts such as golf clubs, bicycles, motorcycles, agricultural machinery, due to the abrasion which occurs each time the user or worker grips them, abrasion resistance is sought in the rubber compositions for the grips as well.
DISCLOSURE OF INVENTION
Accordingly, an object of the present invention is to provide rubber compositions which solve the problems inherent to rubber compositions containing silica and are superior in processability in the unvulcanized state and the physical properties of the vulcanizates and which are superior in the properties sought for the applications of footwear, conveyor belt covers, rolls, hoses, cables, rubberized fabrics, and grips depending upon those applications.
In accordance with the present invention, there is provided a rubber composition comprising (A) an elastomer, (B) a filler, (C) a polysiloxane having the formula (I) having an average degree of polymerization of 3 to 1000:
wherein, R
1
is a C
1
to C
18
substituted or unsubstituted monovalent hydrocarbon group which may contain an ether bond, R
2
is a hydrogen atom or a C
1
to C
18
substituted or unsubstituted monovalent hydrocarbon group, R
3
is a methyl group or phenyl group, m is an integer of 1 or more, and n is 0 or a positive integer and, optionally, (D) a silane coupling agent.
Namely, according to the first embodiment of the present invention, there is provided a rubber composition for footwear comprising (A) 100 parts by weight of an elastomer, (B) 5 to 150 parts by weight of a filler, and (C) 1 to 100 parts by weight, based upon 100 parts by weight of the filler (B), of a polysiloxane represented by the formula (I) having an average degree of polymerization of 3 to 1000.
According to the second embodiment of the present invention, there is provided a rubber composition for a cover of a conveyor belt comprising (A) 100 parts by weight of an elastomer, (B) 5 to 150 parts by weight of a filler, and (C) 1 to 50 parts by weight, based upon 100 parts by weight of the filler (B), of a polysiloxane represented by the formula (I) having an average degree of polymerization of 3 to 1000.
According to the third embodiment of the present invention, there is provided a rubber composition for a roll comprising (A) 100 parts by weight of an elastomer, (B) 5 to 150 parts by weight of a filler, and (C) 1 to 100 parts by weight, based upon 100 parts by weight of the filler (B), of a polysiloxane represented by the formula (I) having an average degree of polymerization of 3 to 1000.
According to the fourth embodiment of the present invention, there is provided a rubber composition for a hose comprising (A) 100 parts by weight of an elastomer, (B) 5 to 200 parts by weight of a filler, and (C) 1 to 40 parts by weight, based upon 100 parts by weight of the filler (B), of a polysiloxane represented by the formula (I) having an average degree of polymerizati
Ishikawa Kazunori
Kaido Hiroyuki
Onoi Hidekazu
Dawson Robert
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
Robertson Jeffrey B.
The Yokohama Rubber Co. Ltd.
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