| PATENT ASSIGNEE'S COUNTRY | Japan |
| UPDATE | 08.00 |
| PATENT NUMBER | This data is not available for free |
| PATENT GRANT DATE | 08.08.00 |
| PATENT TITLE |
Electrophotographic photoreceptor and a production method of the same |
| PATENT ABSTRACT |
An electrophotographic photoreceptor is disclosed. The topmost layer comprises a binder comprising a crosslinked resin having, as a recurring unit, (a) a portion comprising a constituent having a fluorine or silicon atom at the side chain, (b) a portion having an aromatic group in the main or side chain, and (c) a portion having a hydroxyl group or an amino group. |
| PATENT INVENTORS | This data is not available for free |
| PATENT ASSIGNEE | This data is not available for free |
| PATENT FILE DATE | 16.07.98 |
| PATENT FOREIGN APPLICATION PRIORITY DATA | This data is not available for free |
| PATENT REFERENCES CITED | This data is not available for free |
| PATENT CLAIMS |
What is claimed is: 1. An electrophotographic photoreceptor comprising a support having a photosensitive layer, wherein the topmost layer of the photoreceptor is a charge transport layer, and comprises charge transport material and a binder comprising a crosslinked resin having, as a recurring unit, (a) a portion comprising a constituent having a fluorine or silicon atom at the side chain, (b) a portion having an aromatic group in the main or side chain, and (c) a portion having a hydroxyl group or an amino group. 2. The electrophotographic photoreceptor of claim 1 wherein water contact angle of the photosensitive layer is not less than 90 degrees. 3. The electrophotographic photoreceptor of claim 1 wherein the resin is crosslinked by employing a two or more valent or higher valent isocyanate compound crosslinking agent. 4. The electrophotographic photoreceptor of claim 3 wherein the resin is crosslinked by employing a divalent isocyanate compound crosslinking agent. 5. The electrophotographic photoreceptor of claim 1 wherein a resin before crosslinking comprises at least one of a partial structure represented by general formulas (1) through (8); ##STR9## wherein R.sub.1 and R.sub.2 each is an alkyl group or an aryl group; X is a hydrogen atom, or an alkyl group, an aryl group, or an organic group comprising a fluorine or silicon atom, each of which groups may combine directly or indirectly via a carbonyl group. R.sub.3 is a hydrogen atom or an alkyl group having from 1 to 3 carbon atoms; R.sub.4 is a hydrogen atom, an alkyl group, or an aryl group; R.sub.5 is a hydrogen atom, a halogen atom, an alkyl group having from 1 to 4 carbon atoms, an aryl group, or an alkoxy group, and the number of R.sub.5 may be 1 or more, while n is a positive integer; R.sub.6 and R.sub.7 each is a hydrogen atom, an alkyl group or an aryl group and R.sub.6 and R.sub.7 may combine with each other to form a ring; R.sub.8 and R.sub.9 each is a hydrogen atom, a halogen atom, an alkyl group, an aryl group, or an alkoxy group, and the number of R.sub.8 and R.sub.9 each may be 1 or more. 6. The electrophotographic photoreceptor of claim 5 wherein X is an alkyl or aryl group substituted by one or more fluorine atoms or a group represented by a formula; ##STR10## wherein Y.sub.1, Y.sub.2, and Y.sub.3 each is an alkyl group, an aryl group or --SiY.sub.11 Y.sub.21 Y.sub.31, wherein each of Y.sub.11, Y.sub.21 and Y.sub.31 is an alkyl or aryl group. 7. The electrophotographic photoreceptor of claim 5 wherein a resin before crosslinking comprises a partial structure represented by general formula (8). 8. The electrophotographic photoreceptor of claim 1 wherein the topmost layer is provided by coating composition comprising a resin, before crosslinking, and an isocyanate compound having two functional groups or more per molecule is coated employing a circular flow amount control coating device. 9. The electrophotographic photoreceptor of claim 1 wherein the photosensitive layer has a charge generation layer under the charge transport layer. 10. The electrophotographic photoreceptor of claim 9 wherein the support is electroconductive, an interlayer is provided between the charge generation layer and the support. |
| PATENT DESCRIPTION |
BACKGROUND OF THE INVENTION The present invention relates to an electrophotographic photoreceptor employed in copiers, printers and the like, and more specifically to an electrophotographic photoreceptor which exhibits excellent durability. Thirty years, and more, have passed since electrophotographic copiers were introduced onto the market. In the early years, photoreceptors, comprised of inorganic photoconductive materials such as selenium, zinc oxide, cadmium sulfide, etc., were widely employed. However, in recent years, electrophotographic organic photoconductors have been mainly employed which exhibit lower cost, non-toxicity, excellent processability, and large selection range to match specific requirements. However, such organic photoreceptors present various problems. Generally, in order to form an image employing an electrophotographic method, the surface of a photoreceptor is subjected to charging, image exposure, and development to form a toner image; the resulting toner image is transferred onto a transfer material, and is then fixed to obtain an image. After the transfer of the toner image, the photoreceptor is subjected to cleaning of the residual toner and discharging, and is repeatedly utilized over an extended period. Accordingly, the above-mentioned photoreceptor is required to exhibit excellent electrophotographic properties such as charge potential, dark decay potential, residual potential, etc.; excellent physical properties such as printing durability over repeated usage, abrasion resistance, moisture resistance, etc.; excellent durability against ozone generated during corona discharging and image exposure light. Fatigue degradation of a photoreceptor caused by the repeated usage is considered to be caused by the abrasion and damage of the photoreceptor surface due to friction and adhesion of paper dust onto the surface during each process of the transfer of a toner image formed on the photoreceptor onto a transfer material, separation, and cleaning of the surface of the photoreceptor after the transfer, and furthermore, decomposition, deterioration, etc. of the photosensitive layer during each process of charging, image exposure, discharging subjected to the surface of the photoreceptor. Accordingly, in order to minimize the fatigue degradation of the organic photoreceptor, improvements in the physical properties of the photosensitive layer are required. The photosensitive layer of the organic photoreceptor is softer than that of the inorganic photoreceptor, and because the photoconductive material is an organic one, the fatigue degradation of the photoreceptor during the repeated usage is more pronounced. Thus, improvement in the binder employed in the photosensitive layer becomes critical. Proposed for the purpose of improving the mechanical strength of the photoreceptor, for example, are those in which a charge generating material is dispersed into a crosslinking resin such as a urethane resin (Japanese Patent Publication Open to Public Inspection No. 51-23738) and those in which a crosslinking resin is employed in a charge transport layer (Japanese Patent Publication Open to Public Inspection No. 56-48637); and further, Japanese Patent Publication Open to Public Inspection No. 56-48637 discloses a technique in which a protective layer is provided on the photosensitive layer. Such techniques known in the art improve physical properties. On the contrary, however, some charge transport material is deposited in the charge transport layer due to insufficient compatibility between the charge transport material and the resin. This exhibits a disadvantage which adversely affects electrostatic properties such as sensitivity of the photoreceptor, residual potential, etc. Therefore, recently, a photoreceptor has been proposed which comprises a modified phenoxy resin in which physical properties are improved (Japanese Patent Publication Open to Public Inspection No. 7-160012). According to inventions mentioned above, results to meet requirements, to some extent, have been obtained for the improvement in mechanical strength of the organic photoreceptor, and compatibility between the resin and the charge transport material. However, in recent years, the improvements in durability of the photoreceptor have been increasingly demanded, and actually, these requirements have not yet been fully met. SUMMARY OF THE INVENTION An object of the present invention is to provide a photoreceptor which exhibits high mechanical durability, and improvements in cleaning properties as well as paper dust adhesion properties. Another object of the present invention is to provide a photoreceptor which exhibits, in addition to the above performance, excellent compatibility with a charge transport material and minimized effect of temperature on the electrical properties. The present invention and its preferable embodiments are described. An electrophotographic photoreceptor comprises, at the topmost layer, a binder comprising a crosslinked a resin having, as a recurring unit, (a) a portion comprising a constituent having a fluorine or silicon atom at the side chain, (b) a portion having an aromatic group in the main or side chain, and (c) a portion having a hydroxyl group or an amino group. The water contact angle of the photosensitive layer of the electrophotographic photoreceptor is preferably not less than 90 degrees. In the electrophotographic photoreceptor a divalent or higher isocyanate compound as a crosslinking agent is preferably employed. In the electrophotographic photoreceptor a resin before crosslinking comprises a partial structure represented by general formulas (1) through (8) mentioned below. ##STR1## wherein R.sub.1 and R.sub.2 each represents an alkyl group or an aryl group. In general formulas (1) through (8), X represents a hydrogen atom or an alkyl group, an aryl group, or an organic group comprising a fluorine or silicon atom. Each of the alkyl group, the aryl group and the organic group may combine directly or indirectly via a carbonyl group. In general formulas (2) through (7), R.sub.3 represents a hydrogen atom or an alkyl group having from 1 to 3 carbon atoms; R.sub.4 represents a hydrogen atom, an alkyl group, or an aryl group; R.sub.5 represents a hydrogen atom, a halogen atom, an alkyl group having from 1 to 4 carbon atoms, an aryl group, or an alkoxy group, and the number of R.sub.5 may be 1 or more, while n represents a positive integer. n is preferably 0 to 10 and more preferably 0 to 6. In general formula (8), R.sub.6 and R.sub.7 each represents a hydrogen atom, an alkyl group or an aryl group and R.sub.6 and R.sub.7 may combine with each other to form a ring. R.sub.8 and R.sub.9 each represents a hydrogen atom, a halogen atom, an alkyl group, an aryl group, or an alkoxy group, and the number of R.sub.7 or R.sub.8 may be 1 or more. The recurring unit (8) is preferable among the recurring unit represented by general formulae (1) to (8). Example of the organic group comprising a fluorine includes an alkyl or aryl group substituted by one or more fluorine atoms. Example of the organic group comprising a silicon atom includes those represented by the formula; ##STR2## wherein Y1, Y2, and Y3 each represents an alkyl group, an aryl group or --SiY.sub.11 Y.sub.21 Y.sub.31, wherein each of Y.sub.11, Y.sub.21 and Y.sub.31 is an alkyl or aryl group. In a production method of a photoreceptor described above, the electrophotographic photoreceptor is produced by coating composition comprising a resin, before crosslinking, and an isocyanate compound having two functional groups or more per molecule is coated employing a circular flow amount control type coating device. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view showing a layer constitution of an electrophotographic photoreceptor. FIG. 2 is a schematic sectional view of the coating device according to the invention. FIG. 3 is a perspective view of the coating device according to the present invention. FIG. 4 is a schematic sectional view of the coating device according to the present invention. FIG. 5 is a schematic sectional view of the coating device according to the present invention. |
| PATENT EXAMPLES | This data is not available for free |
| PATENT PHOTOCOPY | Available on request |
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