Polymer composition for conductive roller, polymer composition, conductive roller, and conductive belt

Abstract

A polymer composition for a conductive roller composed of a rubber component whose main component is an epichlorohidrin rubber containing ethylene oxide at not less than 55 mol % nor more than 95 mol %. Thioureas are added to 100 g of the rubber component as a crosslinking agent at a rate not less than 0.014 mol nor more than 0.080 mol. In a compression set test of a vulcanized rubber described in JIS K6262, a compression set measured at 70° C. for 22-24 hours is less than 15%; and in a volume resistivity value test described in JIS K6911, a volume resistivity value measured at an applied voltage of 1000V is less than 107.5 [Ω·cm].

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a polymer composition for a conductive roller, a polymer composition, a conductive roller, and a conductive belt. More particularly, the conductive roller and the conductive belt are used for a conductive mechanism of an electrophotographic device of office appliances such as a copying machine, a printer, and the like. The polymer composition can be used effectively for conductive rollers, having a low electric resistance value, such as a developing roller, a charging roller, and a transfer roller for a color copying machine and a color printer. The present invention also relates to improvement of the state of the polymer composition when it is foamed to form the conductive roller such as the transfer roller, the developing roller, the charging roller, and a toner supply roller thereof and productivity of the conductive roller. [0003] 2. Description of the Related Art [0004] It is ne...

AI Technical Summary

Benefits of technology

[0035] The polymer composition for the conductive roller of the first invention contains the rubber component whose main component is the epichlorohidrin rubber containing the specified amount of the ethylene oxide. Therefore it is possible to prevent occurrence of bleeding and stain of a photosensitive member. It is also possible to reduce the volume resistivity value and compression set of the polymer composition. Since the value of the volume resistivity and that of the compression set are specified to the above range respectively, the polymer composition can be very favorably used to compose the conductive roller.

[0112] As the age resistor, it is possible to list imidazoles such as 2-melcaptobenzimidazole; amines such as phenyl-α-naphthylamine, N,N′-di-β-naphthyl-p-phenylenediamine; N-phenyl-N′-isopropyl-p-phenylenediamine; and phenols such as di-t-butyl-p-cresol, and styrenated phenol. In particular, CD (4,4′(α,α-dimethylbenzyl)diphenylamine) of the amines, MB (2-melcaptobenzimidazole) of the imidazoles, MBZ (zinc salt of 2-melcaptobenzimidazole), NBC (nickel dibutyldithiocarbamate) of the phenols are effective. Although these age resistors can be used singly, it is preferable to use two or three thereof in combination to prevent occurrence of blooming.

Problems solved by technology

Thus it is very difficult to control the electric resistance.

In addition, because it is difficult for the conductive filler to disperse uniformly in the polymer composition, an electric resistance value has variations in the circumferential and widthwise directions of the roller.

In particular, in the case where the carbon black is used as the conductive filler, there is no stable correlation between the addition amount of the carbon black and the volume resistivity of the polymer.

However, it is difficult to lower the electric resistance value of the ionic-conductive polymer composition.

However it is difficult to obtain a volume resistivity value lower than 107.8 or 107.9.

Even though an additive for increasing the ionic conductivity is used, it is impossible to make the electric resistance value of the acrylonitrile-butadiene rubber lower than 108.0 [Ω·cm].

However, the electric resistance will increase and the compression set will deteriorate.

Thus, the use of the peroxide vulcanizing system is unpractical.

Thus the vulcanizing system using the derivative of the 2,3 dimethyl quinoxaline is not of practical use.

Therefore it is difficult to use the epichlorohidrin rubber composition for a charging roller or a developing roller which contacts the photosensitive member directly.

Further since the epichlorohidrin rubber composition has a high compression set, there occurs problems in the durability and precision maintenance of an image-forming process system including the roller.

However, the use of the ethylene thiourea and the hydrotalcite does not have a sufficient crosslinking efficiency.

Therefore the rubber composition is not of practical use

Furthermore the former has problems in preventing the photosensitive member from being stained and realizing a low compression set.

Thus the manufacturing cost is high owing to the labor of setting the mixture in the receiving die and equipment expense and the productivity will be low.

Thus the productivity is low.

Consequently the vulcanizing speed will decrease, the productivity will be low, the strength of the foamed polymer composition will be low, and the photosensitive member may be stained in dependence on a case.

In this case, a scorch time takes long even though the urea assistant foaming agent is not used and inhibition of vulcanization occurs.

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