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...
Patent
1998-05-11
2000-03-28
Cain, Edward J.
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...
524495, C08K 300
Patent
active
060433086
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to conductive rubber compositions and a production process thereof, and more particularly to conductive rubber compositions capable of controlling the hardness and electric resistance values of products molded or formed therefrom within respective predetermined ranges, and a production process thereof. The conductive rubber compositions according to the present invention are particularly suitable for use as rubber materials for conductive rubber members such as conductive rolls and conductive blades used in image forming apparatus (electrostatic developing machines) such as electrophotographic copying machines and electrostatic recording apparatus.
BACKGROUND ART
A rubber vulcanizate (molded or formed product of conductive rubber) obtained by forming a rubber composition, in which conductive particles have been incorporated, into a predetermined shape and then vulcanizing it is required to control the hardness and electric resistance value thereof within respective predetermined ranges according to the use application thereof. However, the rubber vulcanizate containing the conductive particles has involved a problem that when a compounding proportion of the conductive particles is made high to achieve a sufficiently low electric resistance value, its hardness becomes too high. When the hardness thereof is controlled by adding a compounding ingredient such as a softener in a great amount, there is offered a problem that the compounding ingredient bleeds out into the surface of the molded or formed product of the conductive rubber. Accordingly, a difficult problem is encountered on the provision of a molded or formed product of conductive rubber, which combines good electrical conductivity with good softness.
When the desired properties cannot be achieve by only one rubber component, it is generally conducted to use a plurality of rubber materials in combination. Even when at least two rubber components are used in combination, however, it is difficult to obtain a molded or formed product of conductive rubber combining good electrical conductivity with good softness by an ordinary method in which vulcanizing agents corresponding to the respective rubber components are used to vulcanize the rubber components at the same time. More specifically, when the individual rubber components are compatible with each other, the hardness of the resulting molded or formed product becomes high because conductive particles are evenly dispersed in the rubber components. Even when the individual rubber components are incompatible with each other, the hardness of the resulting molded or formed product becomes high because the conductive particles are also evenly dispersed in the rubber components unless there is a particular difference in affinity for the conductive particles between the rubber components.
When the individual rubber components are incompatible with each other, and there is a difference in affinity for the conductive particles between the rubber components, the conductive particles come to exist at a higher concentration in the phase of the rubber component having higher affinity for the conductive particles. In this case, the phase of the rubber component having lower affinity for the conductive particles and containing the conductive particles at a lower concentration contributes to good softness. However, the kinds of usable rubber components are naturally limited in the method of controlling the electrical conductivity and softness by the difference in the affinity for the conductive particles, so that it is difficult to satisfy other properties such as abrasion resistance.
Conductive members such as conductive rolls and conductive blades used in image forming apparatus such as electrophotographic copying machines and electrostatic recording apparatus are required to combine good softness with good electrical conductivity. Therefore, the above-described problems will hereinafter be described in more detail taking the case of these conductive members.
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REFERENCES:
patent: 5140371 (1992-08-01), Ishihara et al.
Maeda Kouichirou
Tanahashi Naoki
Cain Edward J.
Nippon Zeon Co. Ltd.
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