Compositions – Electrically conductive or emissive compositions – Elemental carbon containing
Reexamination Certificate
2003-04-11
2004-11-09
Gupta, Yogendra N. (Department: 1751)
Compositions
Electrically conductive or emissive compositions
Elemental carbon containing
C252S502000, C252S518100, C525S240000, C525S243000, C521S140000
Reexamination Certificate
active
06814892
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ethylene propylene rubber foam which is improved in its compression set. More particularly, the present invention pertains to an ethylene propylene rubber foam well suited for use as a material which forms a member to be installed in electrophotographic equipment and electrostatic recording equipment such as a copying machine, facsimile equipment and a printer; to a member such as a transfer member composed of this rubber foam; and image formation equipment (I) equipped with the above-mentioned member.
The present invention is of such a system that directly injects electrical charge by applying voltage so as to electrify an image formation body. Thus the present invention further relates to an electrifying member which comprises an electroconductive ethylene propylene rubber foam and which is capable of suppressing the generation of a defective image; and electrifying equipment and image formation equipment (II) each equipped with the above mentioned electrifying member.
2. Description of the Related Arts
In electrostatic recording equipment and electrophotographic system such as a copying machine, facsimile equipment and a printer, there have heretofore been employed a variety of members such as a transfer roller, a bias roller, a backup roller, a toner feeding roller, a cleaning roller and a paper feeding roller in addition to an electrifying roller used for the purpose of electrifying an image formation member. As the material for forming the above-mentioned member, an ethylene propylene rubber foam is used in the majority of cases.
The major reasons for the frequent use of the ethylene propylene rubber foam are that said rubber foam is stable against ozone, NO
x
, heat and the like, and has favorable durability.
However, because of its large compression set, the ethylene propylene rubber foam is involved in such a problem that the rubber foam sometimes causes defective image due to deformation when a member composed of an ethylene propylene rubber foam is brought into contact with an other member for a long period of time.
Under such circumstances, an attempt is made to improve the compression set of an ethylene propylene rubber foam through a method in which the content of the rubber component is increased by decreasing the contents of a filler and/or a process oil in a crude rubber composition. An increase in the content of the rubber component, however, brings about such problems that molding processability of the rubber composition is worsened and at the same time, foaming cells are made coarse.
On the one hand, in electrophotographic equipment and electrostatic recording equipment such as a printer and a copying machine, electrifying equipment of corona discharge system has heretofore been employed as electrifying equipment for electrifying an object of electrification such as an electrophotographic photoreceptor and electrostatic recording body. However, the aforesaid corona discharge system unfavorably requires a high voltage in the range of 5 to 10 kV, and besides is involved in an environmental problem due to the generation of a large amount of ozone in the course of corona discharge.
In such circumstances, a contact electrification system has recently been put into extensive practice wherein an electrifying member to which voltage is applied is brought into contact with an object of electrification such as a photoreceptor so as to electrify the aforesaid object. The above-mentioned electrification system is advantageous in that the applied voltage can be lowered and besides, the ozone generation can be decreased as compared with the corona discharge system. Nevertheless, the conventional contact electrification system, which majorly utilizes atmospheric discharge that is carried out through a slight clearance between an electrifying member and an image formation body, has not necessarily been satisfactory, since it is incapable of sufficiently preventing the ozone generation.
In addition, the application of direct current voltage only by bringing an electrifying member into contact with an object of electrification gives rise to the difficulty in uniformly electrifying the object of electrification, thereby causing a fear of uneven electrification. It is a general practice as a countermeasure thereagainst to superimpose alternate current and direct current, whereby serious problem is brought about in that vibration occurs between the object of electrification and the electrifying member, inevitably causing unfavorable noise.
Such being the case, the present inventors proposed the electrification system in which a charge is directly injected from an electrifying member to an object of electrification without being accompanied with atmospheric discharge {refer to Japanese Patent Application Laid-Open No. 210283/1993 (Heisei-5)}. In the above proposed system, electrification is carried out by means of direct charge injection by bringing an electrifying member into contact with an object of electrification so as to apply direct current voltage basically without being accompanied by atmospheric discharge through appropriate adjustment between the applied voltage and the electrostatic capacities of the electrifying member and the object of electrification. Thus, said system possesses such advantages that the system enables electrification at a low voltage, since the voltage for the start of discharge needed for atmospheric discharge is dispensed with, that the system is substantially free from ozone generation, and that the system is substantially free from the problem of noise generation caused by application of alternate current voltage.
As mentioned hereinbefore, the direct charge injection system is a favorable system in principle, but is involved in various problems to be solved in order that it is brought to practical use. That is to say, unless the object of electrification is brought into close contact with the electrifying member, part of the object of electrification which is non-electrified tends to remain. When an image is formed in such a state, there are sometimes caused in part such defects as fog, black points, white points, white streaks, black streaks and unevenness. When the pushing pressure is enhanced in order to bring the electrifying member into close contact with the object of electrification, part of the aforesaid object is scraped off, thereby causing the problem of defective image. As a countermeasure thereagainst it is proposed to constitute the electrifying member of an elastic foam, but as a matter of fact, the above-mentioned defect and trouble are not yet prevented at the present time.
SUMMARY OF THE INVENTION
The present invention was made in the light of the above-mentioned circumstances. Thus a general object thereof is to provide an ethylene propylene rubber foam which has improved compression set and stabilized microcells; a member which comprises the aforesaid ethylene propylene rubber foam, and which is used for a variety of image formation equipment; and image formation equipment (I) equipped with the aforesaid member.
Moreover, the present invention is of such a system that electrifies an image formation body through direct injection of electrical charge by applying voltage thereto. Thus another object thereof is to provide an electrifying member which comprises an electroconductive ethylene propylene rubber foam and which is capable of suppressing the generation of a defective image; and electrifying equipment and image formation equipment (II) each equipped with the above mentioned electrifying member.
Other objects of the present invention will be obvious from the text of this specification hereinafter disclosed.
In such circumstances, intensive research and investigation were carried out by the present inventors in order to achieve the above-mentioned objects. As a result, it has been found that it is made possible to obtain an ethylene propylene rubber foam which has improved compression set and stabilized microcell foam by
Kawagoe Takahiro
Nakajima Tadashi
Osaki Toshiyuki
Yamada Chikara
Bridgestone Corporation
Gupta Yogendra N.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Vijayakumar Kallambella
LandOfFree
Ethylene propylene rubber foam and image formation equipment does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Ethylene propylene rubber foam and image formation equipment, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Ethylene propylene rubber foam and image formation equipment will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3284312