Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Radiation-sensitive composition or product
Reexamination Certificate
2000-01-07
2001-07-10
Chapman, Mark (Department: 1753)
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Radiation-sensitive composition or product
C430S067000, C430S056000, C430S059600, C430S096000
Reexamination Certificate
active
06258499
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an electrophotographic photoreceptor, an image forming method employing said electrophotographic photoreceptor, an image forming apparatus and an apparatus unit removably attached to said image forming apparatus.
BACKGROUND OF THE INVENTION
Conventionally, inorganic photoreceptors comprised of inorganic photoconductive materials such as selenium, cadmium sulfide, amorphous silicon and the like have been employed. However, said inorganic photoreceptors have had many problems such that the production is complicated, many of them exhibit toxicity, and are not preferred from the viewpoint of environmental protection as well as health.
Accordingly, instead of the aforementioned inorganic photoconductors, research and development have been increasingly carried out for organic photoreceptors comprised of organic photoconductive materials, which are not toxic, are easily produced, and exhibit wide option for the selection. Of the aforementioned organic photoreceptors, a function separation type photoreceptor comprised of a charge generating layer (CGL) comprising a charge generating material and a charge transport layer (CTL) comprising a charge transport material (CTM) in this order is now in main stream. Further, digital imaging has been progressed in which an image is formed on said photoreceptor employing, for example, light from a light emitting diode, a laser beam, or the like. Being based on this, enhancement in image quality has been demanded.
However, the aforementioned organic photoreceptors have had problems in which the mechanical abrasion resistance is small and repeated charging and exposure readily result in fatigue deterioration, compared to inorganic photoreceptors.
Thus, as means to enhance the abrasion resistance of the aforementioned organic photoreceptor (hereinafter simply referred to as photoreceptor), are known methods in which a the polymerization degree of a binder resin is increased, filler is added to a binder resin, a solid lubricating agent such as polytetrafluoroethylene (PTFE) is added to the surface of a photoreceptor and a friction coefficient between the photoreceptor and the cleaning blade as a cleaning means is decreased, and the like.
SUMMARY OF THE INVENTION
The increase in polymerization degree of a binder resin and the addition of filler enhance the abrasion resistance of the photoreceptor when employed for repeated image formation, and the abraded amount of the photosensitive layer may be decreased. However, phenomena occur in which cleaning properties are degraded, and problems have occurred with the fatigue degradation of a photoreceptor due to filming, the reversing of a blade, and the like.
On the other hand, by applying the solid lubricating agent onto the surface of the photoreceptor, it is found that the cleaning properties are enhanced due to decrease in friction between the photoreceptor and the cleaning blade. However, problems have occurred in which the strength of the photosensitive layer decreases and no sufficient abrasion resistance is obtained.
An object of the present invention is to provide a photoreceptor which minimizes a decrease in the thickness of the photosensitive layer of said photoreceptor due to abrasion and exhibits excellent abrasion resistance when image formation is repeatedly carried out, and specifically is carried out at high speed, exhibits excellent cleaning properties, minimizes the variation of electric potential at an exposed and unexposed area, and consistently forms sharp and high density images without forming fog, and an image forming method as well as an image forming apparatus employing said photoreceptor, and a unit which is removably attached to the apparatus body of said image forming apparatus.
It has been discovered that the glass transition temperature (in ° C.) as well as the contact angle (in degree) of the surface layer of the photosensitive layer of a photoreceptor with respect to deionized water has a close relationship with the abrasion resistance as well as the cleaning properties of said photoreceptor when images are repeatedly formed.
The present invention and embodiments thereof will be described.
An electrophotographic photoreceptor which comprises an electrically conductive support having thereon a photosensitive layer in which the glass transition temperature of the surface layer of said photosensitive layer is at least 105° C. and the contact angle of said surface layer with respect to deionized water is at least 90°.
The glass transition temperature of the surface layer of the photosensitive layer is preferably at least 120° C. The contact angle of the same with respect to deionized water is preferably at least 97°.
The surface layer preferably comprises polycarbonate containing a Si atom or a F atom.
The viscosity average molecular weight of the polycarbonate is preferably at least 50,000.
Examples of preferred polycarbonates are copolymers having a structure unit represented by formula (1).
wherein Y
1
represents an alkylene group having from 1 to 6 carbon atoms or an alkylidene group, R
1
through R
8
each represents a hydrogen atom, a substituted or unsubstituted alkyl group having from 1 to 10 carbon atoms, or a substituted or unsubstituted aryl group, n represents an integer from 1 to 4, and the sum of p and q represents an integer of 1 to 200.
Examples of other preferred polycarbonates are copolymers having a structure unit represented by formula (2).
wherein X represents a straight chain or branched chain or a cyclic alkylidene group having from 1 to 15 carbon atoms, an alkylidene group substituted with an aryl group, an arylenediaklylidene group, —O—, —S—, —CO—, —SO—, or —SO
2
—, and at least one of Z
1
through Z
4
represents a Si atom-containing group represented by formula (2′) and each of others represents a hydrogen atom, an alkyl group having from 1 to 6 carbon atoms, and an aryl group.
wherein Y
2
represents an alkylene group having from 1 to 6 carbon atoms or an alkylidene group, R
9
through R
15
each represents a substituted or unsubstituted alkyl group having from 1 to 10 carbon atoms, or a substituted or unsubstituted aryl group, and the sum of r and s represents an integer of 1 to 200.
The polycarbonates preferably have a F atom containing structural units in the copolymer structure or at the terminal.
An electrophotographic photoreceptor which comprises an electrically conductive support having thereon a photosensitive layer in which the glass transition temperature of the surface layer of said photosensitive layer is at least 105° C. and said surface layer comprises fine organic resin particles having a volume average particle diameter of no more than 5 &mgr;m.
Fine organic resin particles are preferably those containing a F atom.
The example of the surface layer is a charge transport layer. Said charge transport layer preferably comprises a charge transport material having a molecular weight of at least 750, and more preferably comprises the same having a molecular weight of at least 900.
The content of the charge transport material in the charge transport layer is preferably no more than 30 percent by weight.
An image may be formed on said photoreceptor by employing a latent image forming means which forms an electrostatic latent image, a transfer means which transfers the toner image on said electrophotographic photoreceptor visualized by development, and a cleaning means which removes the toner which remains on said electrophotographic photoreceptor after transferring the toner image.
In an image forming method, an electrostatic latent image may be formed on the electrophotographic photoreceptor which moves in a line speed of 400 mm/second, and may be subjected to development, transfer, and cleaning.
An electrophotographic photoreceptor may be applied to an apparatus unit which is integrally supported with at least one of a latent image forming means which forms an electrostatic latent image on said electrophotographic photoreceptor, a transfer means which transfers the toner imag
Bierman Jordan B.
Bierman, Muserlian and Lucas
Chapman Mark
Konica Corporation
LandOfFree
Electrophotographic photoreceptor, an image forming method,... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Electrophotographic photoreceptor, an image forming method,..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Electrophotographic photoreceptor, an image forming method,... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2436568