Stock material or miscellaneous articles – Web or sheet containing structurally defined element or... – Noninterengaged fiber-containing paper-free web or sheet...
Reexamination Certificate
1999-12-21
2001-06-12
Weisberger, Richard (Department: 1774)
Stock material or miscellaneous articles
Web or sheet containing structurally defined element or...
Noninterengaged fiber-containing paper-free web or sheet...
C428S295100, C428S500000, C492S025000, C399S130000, C399S154000, C399S162000, C525S403000
Reexamination Certificate
active
06245420
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to rubber belts and, more particularly, to a rubber belt that can be used to transfer an image to an object.
2. Background Art
Electrophotography is one form of electrostatography used in duplication. One process for performing electrophotographic duplication is carried out as follows. The first step is a charging step which involves applying a uniform electrostatic charge to a surface of a photoreceptor. An exposure step is then carried out to irradiate the charged photoreceptor with a light source, such as a laser light, to charge a predetermined pattern. In a development step, an image is formed by attaching a toner with the electrostatic charge. In a transfer step, the toner, defining the image, is transferred to ordinary paper or a film that is oppositely charged. The image is then fixed by transporting the paper or film, with the attached toner, through a heated fixing roll. Thereafter, the remaining charge and toner are removed to allow the photoreceptor to be reused.
In a conventional duplicating apparatus, the above development step is carried out by applying toner through the electrostatic charge developed on a transfer drum in contact with the photoreceptor. Generally, this mechanism involves a large number of parts, among which are a transfer drum, rollers, a charger, etc. As a result, the equipment tends to become complicated and expensive. With a large diameter transfer drum, operation of the transfer drum at high speeds tends to cause ordinary paper in contact with the transfer drum to attach thereto and cause clogs or jams.
In recent years, transfer belts have commonly replaced transfer drums. Transfer belts are often incorporated to produce a space efficient design. Further, the transfer belts are able to effect image transfer at high rotational speeds.
In a typical transfer belt, a conductive powder, such as conductive carbon black, graphite, metallic powder, and the like, is mixed with rubber. Electrical conductivity results from the contact of the particles in the conductive powder with each other. However, it is extremely difficult to uniformly disperse the conductive powder in the rubber. As a result, the resistance tends to vary throughout the transfer belt. As a result, the desired volume resistance may not be maintained in the desired medium resistance range of 10
8
to 10
11
&OHgr;cm.
It is also known to add carbon black to rubber to increase its modulus and thereby reduce the elongation of the belt. Carbon black is generally required to be added at a high density. However, at high density, the carbon black tends to be dispersed non-uniformly, again potentially resulting in non-uniform electrical resistance properties.
It is known to use silica to increase the viscosity of the rubber. However, this tends to reduce workability and the resulting rubber tends to be brittle.
It is also known to produce anti-static properties by mixing a surface active agent and a filler consisting of a metallic oxide in a conductive rubber composition.
However, to achieve desired anti-static properties using the metallic oxide, generally a relatively large amount thereof must be used. While this improves the anti-static characteristics of the rubber, the modulus and permanent distortion resistance tend to decrease. Further, the anti-static characteristics attributable to the use of a surface active agent may be temporary. Bleeding may produce stickiness on the transfer surface. Even after charge removal and cleaning steps are carried out, there may be some residual toner attached to the transfer surface.
It is also known to form a transfer belt using a rubber composition made by mixing rubber, such as ethylene-propylene rubber (EPR), ethylene-propylene-diene rubber (EPDM), natural rubber, SBR, and the like, with epichlorohydrin.
With belts having a rubber composition that is a mix of EPR or EPDM with epichlorohydrin, the problem of the toner clinging to the transfer surface is eliminated to at least a certain extent. However, because the volume resistance of EPDM is typically as high as from 10
15
to 10
18
&OHgr;cm, the amount of EPDM that can be mixed is limited to an amount that produces a resistance in the normally desired range of 10
8
to 10
11
&OHgr;cm. The resulting belt may have a low modulus, which may result in lack of a desired clarity of the transferred image.
SUMMARY OF THE INVENTION
In one form, the invention is directed to a transfer belt for use in an electrostatographic duplicator. The belt has a body defining an image transfer surface. The body is made up of a rubber composition including a combination of epichlorohydrin-ethyleneoxide copolymer and hydrogenated nitrile rubber, to which a metallic salt of an unsaturated carboxylic acid and an organic peroxide are added.
This construction lends itself to making a transfer belt with a volume specific resistance in the medium resistance range of 10
8
to 10
11
&OHgr;cm, with relatively uniform electrical resistance. With this structure a transfer belt may be made with a high modulus and a controlled degree of resistance to permit clear image transfer at relatively high speeds.
The body may further have short fibers embedded therein. The fibers may consist of a polymer graft-bonded to polyamide fibers. The polymer grafted to the fibers may be at least one of polyolefin and rubber.
The fibers may have a diameter not greater than 3.0 &mgr;m.
The short fibers may be present in an amount of no more than 30 parts by weight per 100 parts by weight of the combination of epichlorohydrin-ethyleneoxide copolymer and hydrogenated nitrile rubber.
The body may further include silica present in an amount of 1:50 parts by weight of silica per 100 parts by weight of the combination of epichlorohydrin-ethyleneoxide copolymer and hydrogenated nitrile rubber.
The body may have an endless shape.
The epichlorohydrin-ethyleneoxide copolymer may be at least one of epichlorohydrin-ethyleneoxide-allylglycidylether copolymer and an epichlorohydrin-ethyleneoxide-propyleneoxide-allylglycidylether copolymer.
The hydrogenated nitrile rubber may have an oxidation degree of at least 80%, and more preferably 90%.
The metallic salt of an unsaturated carboxylic acid may be formed by ion-bonding an unsaturated carboxylic acid having a carboxyl group with a metal.
The unsaturated carboxylic acid may have at least one of: a monocarboxylic acid; a monocarboxylic acid that is an acrylic acid; a methacrylic acid; a dicarboxylic acid; a dicarboxylic acid that is a maleic acid; a dicarboxylic acid that is a fumaric acid; and a dicarboxylic acid that is an itaconic acid.
The metal may be at least one of beryllium, magnesium, calcium, strontium, barium, titanium, chromium, molybdenum, manganese, iron, cobalt, nickel, copper, silver, zinc, aluminum, tin, and antimony.
The metallic salt may be an unsaturated carboxylic acid present in an amount of 5-200 parts by weight per 100 parts by weight of the combination of epichlorohydrin-ethyleneoxide copolymer and hydrogenated nitrile rubber.
The organic peroxide may be at least one of di-t-butylperoxide, dicumylperoxide, t-butylcumylperoxide, 1,1-t-butylperoxy-3,3,5-trimethylcyclohexane, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane-3, bis(t-butylperoxydiisopropyl)benzene, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, t-butylperoxy benzoate, and t-butylperoxy-2-ethylhexyl carbonate.
The organic peroxide may be present in an amount of 0.2-10 parts by weight of pure peroxide per 100 parts by weight of the combination of epichlorohydrin-ethyleneoxide copolymer and hydrogenated nitrile rubber.
The ratio of epichlorohydrin-ethyleneoxide copolymer to hydrogenated nitrile rubber may be between 10:90 and 90:10.
The transfer belt may further include a co-crosslinking agent to increase the crosslinking efficiency by the organic peroxide. The co-crosslinking agent may be at least one of TAIC, TAC, maleimide, quinonedioxime, trimethylolpropane trimethacrylate, and sulfur.
The transfer belt may further include
Hasegawa Arata
Hineno Yorifumi
Ishida Kazutoshi
Nishio Hiroyuki
Takada Toshimichi
Mitsuboshi Belting Ltd.
Weisberger Richard
Wood Phillips VanSanten Clark & Mortimer
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