Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Radiation-sensitive composition or product
Reexamination Certificate
2000-12-21
2002-04-09
Goodrow, John (Department: 1753)
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Radiation-sensitive composition or product
C430S132000
Reexamination Certificate
active
06368764
ABSTRACT:
This application is based on the application No. 364334/1999 filed in Japan, the contents of which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a photosensitive member for electrophotography.
2. Description of the Related Art
In the photosensitive member which is recently employed for an electrophotographic equipment, such as an image forming equipment and the like, it is a general technical matter to form a surface protective layer on a surface of an organic photosensitive layer from the viewpoints of preventing an abrasion of the photosensitive layer caused by a cleaning member and the like as well as an injection of a surface charge into the photosensitive layer.
Silicone resin has been known as a material to form the surface protective layer, said silicone resin being constituted by a three-dimensional network of siloxane bond (Si—O—Si bond). However, in the case where the silicone resins are independently employed, a problem of the adhesion between the photosensitive layer and the protective layer has been occurred because the inorganic material is laminated on the organic material, said problem being caused by a difference of a coefficient of thermal expansion between both materials.
Accordingly, a surface protective layer which consists of the silicone resin and a thermoplastic resin has been proposed. However, this proposal brings about the various problems that a sensitivity is worse, an electric potential increases at the time of plate wearing, and an image noise, such as a fog, and image flowing and the like are brought about on the image quality.
In addition, at the time of forming the surface protective layer, it is a general technical matter to apply a coating solution for the surface protective layer which is prepared by dissolving the material for the protective layer such as the silicone resin as well as optional thermoplastic resin and the like in a solvent is applied on the organic photosensitive layer and to cure the applied coating solution. Furthermore, in order to avoid a formation of ununiform interface between the surface protective layer and the photosensitive layer, said formation being caused by a dissolution of the organic photosensitive layer at the time of forming the surface protective layer, it is a general technical matter to employ a solvent which does not dissolve the materials for the photosensitive layer, such as the binder resin, photoconductive material and the like, for example, alcohols, such as methanol, ethanol, 2-propanol and the like (see, for example, Japanese Patent Publication (Kokai) Nos. 51155/1986, 141365/1991, 211561/1991). When the interface between the surface protective layer and the photosensitive layer becomes ununiform, a difference will occur depending on a part of one photosensitive member with respect to the qualities, such as the adhesion between the surface protective layer and the photosensitive layer, the electrostatic properties and the like, said difference bringing about a problem that it becomes a cause of the image noise, such as a image shading and the like.
SUMMARY OF THE INVENTION
The present invention has been carried out in view of the aforementioned situation.
The object of the present invention is to provide a photosensitive member for electrophotography which has excellent adhesion between a surface protective layer and a photosensitive layer as well as electrostatic properties, such as sensitivity and the like, and which prevents an occurrence of an image noise over a long period of time.
The present invention relates to a photosensitive member for electrophotography which comprises:
(i) an electroconductive support,
(ii) an organic photosensitive layer which comprises a charge generating material, a charge transporting material, and a binder resin, and
(iii) a surface protective layer which comprises a thermosetting silicone resin, said surface protective layer being prepared by applying a coating solution comprising the thermosetting silicone resin and a solvent, which can dissolve the binder resin and has a boiling point of 60-130° C. and a solubility parameter of 8-11, onto the organic photosensitive layer and then curing the applied coating solution.
DETAILED DESCRIPTION OF THE INVENTION
The photosensitive member for electrophotography of the present invention is prepared by laminating at least the organic photosensitive layer and the surface protective layer on the electroconductive support in this order. According to the present invention, the specific solvent is employed when the surface protective layer is formed.
To say more precisely, the surface protective layer of the present invention is formed by applying the coating solution for the surface protective layer comprising the specific solvent and the thermosetting silicone resin onto the organic photosensitive layer and then curing the applied coating solution. The coating solution is prepared by dissolving at least the thermosetting silicone resin in the specific solvent.
The solvent employed in the present invention can dissolve the organic photosensitive layer on which the surface protective layer is directly formed or can dissolve at least the binder resin which is one of the components of the organic photosensitive layer, and has the boiling point (under a pressure of 760 mmHg) of 60-130° C., preferably 60-120° C., more preferably 65-115° C. as well as the solubility parameter of 8-11, preferably 8.5-10.5, more preferably 8.5-10. It is thinkable that the adhesion between the surface protective layer and the organic photosensitive layer as well as the electrostatic properties, such as the sensitivity and the like can be improved and the occurrence of the image noise can be prevented over a long period of time because the materials of the organic photosensitive layer can uniformly penetrate into the surface protective layer without making the interface between the surface protective layer and the organic photosensitive layer ununiform by forming the surface protective layer with the specific solvent.
In the present specification, the wording of “the interface between the surface protective layer and the organic photosensitive layer becomes ununiform” means that a clear boundary is not formed between the surface protective layer and the organic photosensitive layer, and a layer wherein the components of the surface protective layer and the organic photosensitive layer exist ununiformly is formed in the region situated in the neighborhood of the boundary between the surface protective layer and the organic photosensitive layer. Although the clear boundary is not formed between the surface protective layer and the organic photosensitive layer in the present invention, it is thinkable that the object of the present invention can be achieved because a layer wherein the components of both layers exist in a comparatively uniform manner is formed between both layers.
As regards the solvent, the wording of “can dissolve the organic photosensitive layer” used in the present specification means that the solvent dissolve the organic photosensitive layer or at least the binder resin of the organic photosensitive layer when the surface protective layer is formed in such a way that the surface protective layer to be prepared has an aftermentioned gradient of ionization potential energy in the inside thereof. When the binder resin is excessively dissolved in the solvent, the formation of the surface protective layer becomes difficult. On the other hand, when the solubility of the binder resin in the solvent is lowered to an undue extent, it is impossible to obtain the effects of the present invention that the adhesion between the surface protective layer and the organic photosensitive layer as well as the electrostatic properties, such as the sensitivity and the like are improved, and that the occurrence of the image noise is prevented over a long period of time. In the case where the organic photosensitive layer on which the surface protective layer is directly formed
Edo Teiko
Inagaki Keiichi
Tokutake Shigeaki
Goodrow John
McDermott & Will & Emery
Minolta Co. , Ltd.
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