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
2001-07-13
2003-12-16
Moore, Margaret G. (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...
C525S109000, C525S481000, C008S115600, C008S115610, C428S365000, C428S375000, C428S395000, C523S206000
Reexamination Certificate
active
06664325
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a reinforcing fiber embedded in rubber or resin to enhance the strength and dimensional stability of the same, and also relates to a fiber processing agent for use in a reinforcing fiber of this kind and a rubber product reinforced by the reinforcing fiber.
BACKGROUND ART
Rubber products and resin products in general have glass fibers or organic fibers embedded therein to enhance the dimensional stability and strength thereof. Glass fibers of this kind have a low affinity to rubber and resin which are organic substances, and therefore have their surfaces coated with films of isocyanate, a halogen-containing polymer, or the like. For example, a glass fiber for reinforcing rubber matrices is disclosed in Japanese Patent Publication (Kokoku) No. 5-71710, which is coated with a three-layer film having a first layer containing a water soluble condensate of resorcinol formaldehyde (hereinafter referred to as “RFL”) and rubber, a second layer containing a halogen-containing polymer and isocyanate, and a third layer formed of rubber which is the same as the rubber matrix. Further, a glass fiber is disclosed in Japanese Laid-Open Patent Publication (Kokai) No. 1-221433, which is coated with a film containing RFL, butadiene-styrene-vinylpyridine-terpolymer, and chlorosulfonated polyethylene.
These films exhibit intermediate properties between those of the glass fiber and those of the rubber matrix or the resin matrix (hereinafter abbreviated as “the matrix”) and have an affinity to both of them to enhance their adhesive strength.
On the other hand, organic fibers have a higher affinity to the matrix compared with glass fibers. However, they still do not have satisfactorily sufficient adhesive strength. To further enhance the adhesive strength, an organic fiber to be used is coated with a film similar to those coated over the glass fibers. For example, Japanese Laid-Open Patent Publication (Kokai) No. 6-25978 discloses an aromatic polyamide-reinforcing fiber which is coated with a two-layer film having a first layer containing a polyepoxide compound having two or more epoxy radicals, and a second layer containing RFL. Further, Japanese Laid-Open Patent Publication (Kokai) No. 10-204780 discloses a polyester fiber which is coated with polyvinyl formaldehyde, aromatic epoxide compound, blocked polyisocyanate compound, and RFL.
The prior art, however, has the following problems:
The above-indicated glass fiber coated with the three-layer film has high adhesive strength since the glass fiber progressively changes in nature or property from the glass fiber to the rubber matrix, so that the glass fiber exhibits high adhesive strength. However, it has a problem of a complicated manufacturing process. On the other hand, the glass fiber coated with the single layer film and the organic fibers as indicated above can be manufactured by simple manufacturing processes, but they cannot be considered to have sufficient strength of adhesion to the matrix.
Besides, it is difficult for the glass fibers and the organic fibers to use a common fiber processing agent due to their different materials. Therefore, respective different exclusive fiber processing agents have been used for the glass fibers and the organic fibers.
The present invention has been devised in order to solve the above problems with the prior art, and it is an object of the invention to provide a reinforcing fiber which can exhibit sufficient adhesive strength even with single layer film coating, a fiber processing agent which can enhance the strength of adhesion between the fiber and the matrix, and a rubber product employing the reinforcing fiber.
DISCLOSURE OF THE INVENTION
To attain the above object, according to a first aspect of the present invention, there is provided a fiber processing agent comprising a rubber modified epoxy resin obtained by epoxidating an acrylonitrile-butadiene copolymer latex.
To attain the above object, according to a second aspect of the present invention, there is provided a fiber processing agent comprising a rubber modified epoxy resin, and a phenol resin.
Preferably, in the fiber processing agent according to the second aspect, the rubber modified epoxy resin and the phenol resin each have a solids content thereof falling within a range of 10 to 90 weight % relative to a total solids content of the fiber processing agent.
More preferably, the rubber modified epoxy resin and the phenol resin are each in an emulsified state.
Preferably, the rubber modified epoxy resin of the fiber processing agent of the second aspect is obtained by epoxidating a butadiene-styrene copolymer latex or an acrylonitrile-butadiene copolymer latex.
Also preferably, in the fiber processing agent according to the first or second aspect, the concentration of the total solids is 10 to 50 weight %.
To attain the above object, according to a third aspect of the present invention, there is provided a reinforcing fiber which has been processed by the fiber processing agent according to the first or second aspect of the invention.
Preferably, the reinforcing fiber according to the present invention comprises a glass fiber or an aramid fiber processed by the fiber processing agent.
More preferably, in the reinforcing fiber according to the present invention, an amount of solids of the fiber processing agent deposited on the fiber is 10 to 30 weight % relative to the weight of the reinforcing fiber.
To attain the above object, according to a fourth aspect of the present invention, there is provided a rubber product which has the reinforcing fiber according to the present invention embedded therein.
Preferably, the rubber product according to the present invention contains the reinforcing fiber in an amount of 10 to 70 weight %.
More preferably, the rubber product according to the present invention comprises a reinforcing fiber including an aramid fiber, and a single-layer film coated over the aramid fiber, and a rubber matrix having the reinforcing fiber embedded therein, and the strength of adhesion between the aramid fiber, the single-layer film, and the rubber matrix is at least 200 kgf/25 mm in width.
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will now be described in detail.
The present invention provides a fiber processing agent which comprises rubber modified epoxy resin. The rubber modified epoxy resin is obtained by epoxidating a high molecular compound having high rubber elasticity which possesses both high elasticity peculiar to rubber, and high adhesive strength due to the epoxidation. The high molecular compound having high rubber elasticity may include a butadiene-styrene copolymer latex, an acrylonitrile-butadiene copolymer latex, a butadiene rubber latex, and an isoprene rubber latex, for example.
These high molecular compounds having a hydroxyl group or an epoxy group as a side chain thereof when epoxidated. The hydroxyl group or epoxy group (hereinafter simply referred to as “the epoxy group”) is a polar group and easily chemically reacts so that it coacts with peripheral substance(s) to enhance the strength of adhesion between high molecular compounds in the film and also enhance the strength of adhesion between the film and the fiber or the matrix. Therefore, a rubber product and a resin product in which is embedded a reinforcing fiber processed by the fiber processing agent according to the invention (hereinafter simply referred to as “the product”) has high solidity as well as high durability and strength.
These rubber modified epoxy resins may be each used singly or may be used in the form of a mixture of two or more of them. In many cases, it is preferable that two or more of the rubber modified epoxy resins should be used in the form of a mixture, though it depends upon the compatibility between the fiber and the matrix. The reason for this is considered to be that the film is required to be intermediate in property between the fiber and the matrix. If a mixture of two or more of the rubber modified epoxy resins is used, the res
Frishauf Holtz Goodman & Chick P.C.
Moore Margaret G.
Nippon Sheet Glass Co. Ltd.
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