US3839033A

US3839033A - Electrophotographic photosensitive member containing a nitrocellulose-polyvinyl pyrrolidone barrier layer

Info

Publication number: US3839033A
Application number: US00264334A
Authority: US
Inventors: H Matsuno; I Endo; K Suzki
Original assignee: Canon Inc
Current assignee: Canon Inc
Priority date: 1971-06-22
Filing date: 1972-06-19
Publication date: 1974-10-01
Anticipated expiration: 1991-10-01
Also published as: DE2229992B2; DE2229992C3; JPS5033778B1; DE2229992A1

Abstract

An electrophotographic photosensitive member comprises a support, a barrier layer overlying the support, the barrier layer comprising a composite of nitrocellulose and polyvinylpyrrolidone, and an organic photoconductive layer overlying the barrier.

Description

United States Patent [191 Matsuno et al.

[45] Oct. 1,1974

[ ELECTROPl-IOTOGRAPl-IIC PHOTOSENSITIVE MEMBER CONTAINING A NITROCELLULOSE-POLYVINYL PYRROLIDONE BARRIER LAYER [75] Inventors: I-Iiroshi Matsuno, Tokyo; Ichiro Endo, Kawasaki; Kiyoshi Suzki, Tokyo, all of Japan [73] Assignee: Canon Kabushiki Kaisha, Tokyo,

Japan [22] Filed: June 19, 1972 [21] Appl. No.: 264,334

[30] Foreign Application Priority Data June 22, 1971 Japan 46-44998 [52] US. Cl. ..96/1.5, 117/218 [51] Int. Cl. G03g 5/00, 603g 5/02 [58] Field of Search 96/15, 1.8; 117/218; 162/138 [56] References Cited UNITED STATES PATENTS 3,245,833 4/1966 Trevoy 117/201 OTHER PUBLICATIONS Chadwell et al., Barrier Layer Suitable For Accept- I ing Dichroic Sensitizer Particles, IBM Technical Disclosure Bulletin, Vol. 14, N0. 5, Oct. 1971, Pg. 1509.

Primary Examiner-David Klein Assistant Examiner-John R. Miller [5 7 ABSTRACT An electrophotographic photosensitive member comprises a support, a barrier layer overlying the support, the barrier layer comprising a composite of nitrocellulose and polyvinylpyrrolidone, and an organic photoconductive layer overlying the barrier.

3 Claims, No Drawings ELECTROPHOTOGRAPHIC PHOTOSENSITIVE MEMBER CONTAINING A NITROCELLULOSE-POLYVINYL PYRROLIDONE BARRIER LAYER BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to an electrophotographic photosensitive member utilizing an organic photoconductive material.

2. Description of the Prior Art Heretofore, there have been known various organic photoconductive materials forming high polymers or of low molecular weight such as poly-N-vinylcarbazole, brominated poly-N-vinylcarbazole, polyvinylanthracene, oxadiazoles, and acylhydrazones. If desired, sensitizers may be added to the organic photoconductors to produce electrophotographic photosensitive members.

Organic photoconductive materials are excellent in points of transparency, flexibility, selectivity of charging polarity and surface smoothness. Particularly, high polymer organic photoconductive materials have film-shapeability.

However, a photosensitive member composed of an organic photoconductive material merely overlying a conductive support is not satisfactory to electrophotographic application since electrostatic problems arise.

In other words, an electrophotographic photosensitive member comprising a conventional organic photoconductive material is often broken by spontaneous discharge after charging by corona discharging and the developed image contains white points which remarkably reduce the image quality.

For the purpose of solving such a drawback, it was proposed to provide a resin adhesive layer between an organic photoconductive layer and a support; However there does not yet exist a resin adhesive layer which does not reduce the sensitivity of a photosensitive layer and can sufficiently prevent discharging destroy.

In electrophotographic processes in which a photosensitive member is repeatedly used, there are various drawbacks, that is, fatigue phenomena such as lowering of charge amount, low uprising of charging, residual charge retention and loweringof sensitivity as well as discharge distruction.

Heretofore, it has been studied to apply a photosensitive member comprising an organic photoconductive material to an electrophotographic process using a photosensitive member repeatedly in charging, exposing, developing and transferring steps. Neither the above mentioned problem is recognized.

A photosensitive member comprising a support and a photosensitive layer composed of ZnO-binder resin, and a barrier layer being provided therebetween is known, but a photosensitive member comprising a support and an organic photoconductive material, and a barrier layer being provided therebetween, is impractical. Practically effective barrier materials have not yet been found.

The present inventors have found particular barrier materials capable of preventing both discharge destruction and fatigue of a photosensitive member used for electrophotographic processes using the photosensitive member repeatedly.

SUMMARY OF THE INVENTION In accordance with the present invention, there is provided an electrophotographic photosensitive member which comprises a support, a barrier layer overlying the support and comprising a composite of nitrocellulose and polyvinylpyrrolidone, and an organic photoconductive layer overlying the barrier layer.

It is an object of this invention to provide an electrophotographic photosensitive member free from discharge destruction and causing fatigue phenomenon only to a less extent upon repeating use.

. DESCRIPTION OF THE PREFERRED EMBODIMENTS Barrier layers used in this invention are to be selected in such a manner that the volume resistivity are of a certain appropriate values so as to completely prevent a discharge destruction and in a photosensitive member used repeatedly the fatigue phenomenon is prevented and the barrier does not disadvantageously effect the electrophotographic characteristics such as photosensitivity.

Barrier layer materials satisfying such requisites are a composite of nitrocellulose and polyvinylpyrrolidone.

There are various nitrocelluloses having various degrees of polymerization and degrees of nitration. These nitrocelluloses may be used for the present invention.

Providing such a barrier between an organic photoconductive layer and a support serves to prevent discharge destruction of the resulting photosensitive member and fatigue of the photosensitive member upon repeated use of the photosensitive member. Furthermore, such a barrier layer enables one to produce an electrophotographic photosensitive member having an electrophotosensitive layer of excellent film characteristics such as adhesivity, flexibility, tensile strength, stable performance and the like.

As a support used in this invention, there may be used various conventional supports used for electrophotographic photosensitive member. Representative supports are metal plates such as aluminum, copper and the like; paper; aluminum laminate paper; synthetic resin film containing surfactant; synthetic resin film treated with a quaternary ammonium salt for imparting conductivity; and glass, paper, and synthetic resin on which metal, metal oxide or metal halide is vapor-deposited. In general, surface resistivity is preferably less than 10 ohm and more preferably less than 10 ohm.

The barrier layer' is formed on the support in such a manner that the barrier material such as nitrocellulose and in an appropriate solvent at a ratio of from 2 8 to 8 2 by weight, and the viscosity is adjusted to such a value that is suitable for coating and the resulting solution is coated on the support according to conventional coating methods followed by drying such as air drying and heat drying to form a barrier layer.

Further, since the barrier layer composed of a composite of nitrocellulose and polyvinylpyrrolidone has a good flexibility, no plasticizer is necessary in preparing a coating solution, but film-shapeability may be more improved by adding 10 to 50 percent of good compatible plasticizer (for example, trichloroethylphosphate,

The film of the resulting barrier layer is soft and strong. and has sufficient flexibility.

Depending upon the purpose of the barrier layer. pigments and other additives may be added in a necessary amount to a coating solution for producing the barrier layer.

The film thickness about the barrier layer is preferably less than about microns, more preferably, 3 to 7 microns. Particularly, in a photosensitive plate for -a master a good result was obtained even when the film thickness of the barrier layer is about 1 micron. When the thickness of the barrier layer is thicker than 10 microns, some experiments show that the electrophotographic sensitivity is adversely affected. When the barrier layer is less than 10 microns thick, there is a hardly recognizable lowering of sensitivity and when the barrier layer is thicker than 3 microns thick, discharge destruction and fatigue phenomenon upon repeated use of the photosensitive member can be prevented.

An organic photoconductive layer is formed on the barrier layer according to conventional methods to produce an electrophotographic photosensitive member of this invention.

As the organic photoconductive materials, there may be used known organic photoconductive material. Particularly preferable materials are organic polymeric photoconductive materials such as poly-N- vinylcarbazole, chlorinated poly-N-vinylcarbazole, brominated poly-N-vinylcarbazole, cyanated poly-N- vinylcarbazole, polyvinylacenaphthene and the like.

Chlorinated poly-N-vinylcarbazole may be obtained by chlorinating poly-N-vinylcarbazole with chlorine gas or sulfuryl chloride, or by polymerizing a chlorinated vinylcarbazole. Detailed preparation methods are disclosed in German Offenlegungsschrift 2035679.

The following examples are given for illustrating the present invention, but not for restriction thereof. Example 1 An aqueous solution of an agent for lowering resistance poly-(N,N-dimethyl-3, S-methylene) piperidinium chloride was coated on a polyethyleneterephthalate film having an undercoating layer (75 microns thick) and dried to form a transparent conductive layer. Then, a 10 percent (by weight) solution of nitrocellulose (RS-2, trade name, supplied by Daiseru, degree of nitration of 11.5 to 12.2 percent) was mixed with a 10 percent solution of polyvinylpyrrolidone (PBP-K90, trade name, supplied by GAF Co.) at a ratio of 2:8 (by weight). Solvents in both solutions above are ethylalcohol-methylalcohol (7:3).

Methyl ethyl ketone was added, in an amount of one half of the mixture, to said mixture to obtain a coating solution of a barrier layer.

The solution thus obtained was coated on the transparent conductive layer at thickness of 3 to 4 microns (when dried) and dried to form a barrier layer. The resulting coating film (barrier layer) was highly transparent, strong and flexible and tightly adhered to the conductive layer. Further, on the barrier layer was coated a photosensitive agent composed of poly-N- vinylcarbazole, Crystal Violet, and benzenechlorobenzene (1:1) at 8 g./m. and dried to form a photosensitive layer. The resulting transparent organic photoconductive film was subjected to a known electrophotographic reproduction procedure, that is, charging, ex-

posing, reduction photographing. and wet-developing to form an excellent positive images. When the positive images were enlarged by a projector. it was found that the film was free from various electrostatic trouble and gave clear and sharp projected images. On the contrary, when a conventional photosensitive member having no barrier layer was used, there were formed considerable white points caused by discharge destroy.

Example 2 On a conductive support composed of polyester film (75 microns thick) having an aluminum vapor deposited layer of visible ray transmitting rate of percent there was coated a mixture obtained by mixing a 5 percent solution of nitrocellulose (RS 20, trade name, supplied by Daiseru, degree of nitration of 11.5 to 12.2 percent) with a 10 percent solution of polyvinylpyrrolidone (PEP-K90, trade name, supplied by GAF Co.) both in ethylalcohol-methylalcohol (7:3) at a ratio of 1:1 (by weight) and adding thereto methyl ethyl ketone and dimethylformamide, each amount of which is one fourth the weight of the above mixture, at 3 to 4 microns thick (when dried) to form a barrier layer and dried. The resulting barrier layer showed excellent properties similar to Example 1. A solution composed of chlorinated poly-N-vinylcarbazole 3 g., N- vinylcarbazole 0.1 g., carbon tetrabromide 0.2 g., and 45 ml. of a mixed solvent of benzene-chlorobenzene (1:1) was irradiated by ultraviolet rays for 20 minutes, stored in a dark place for 6 hours at ambient temperature and coated on the barrier layer. The resulting transparent organic photoconductive film was treated in a way similar to Example 1. Thus, there was obtained excellent transparent positive images free from white points.

Example 3 On a conductor composedof polyester film microns thick) having an aluminum vapor deposited layer of visible ray transmitting rate of 60 percent there was coated a mixture solution which was obtained by in such a way that a 15 percent solution of nitrocellulose (RS /2, trade name, supplied by Daiseru, degree of nitration of 1 1.5 to 12.2 percent) in ethylalcoholmethylalcohol (7:3) was mixed with a 15 percent solution of polyvinylpyrrolidone (PBP-K60, trade name, supplied by GAF Co.) in ethylalcoholmethylalcohol (7:3) at ratio of 8:2 (by weight), and amounts of methyl ethyl ketone and dimethylformamide amount one fourth the above mixture by weight, respectively, was added to said mixture, and 30 percent of trichloroethyl phosphate was added, at thickness of 4 to 5 microns (when dried) to form a barrier layer. As shown in Example l, the resulting barrier layer was transparent, strong, flexible and highly adhesive to the deposited layer.

On the barrier layer there was coated a photosensitive agent composed of a solution of chlorinated poly- N-vinylcarbazole and Rhodamine B in benzenechlorobenzene (1:1) at 5 to 6 g./m. and dried to produce a photosensitive layer.

The resulting photosensitive film was photographically reduced, in a way similar to Example 1, to prduce sharp positive images. The sensitivity was good. When the resulting positive images were enlarged with a projector, there were obtained projected images free from white points and of high fidelity to an original pattern. The film was strong, flexible and highly adhesive.

Example 4 On a baryta paper subjected to a treatment for imparting conductivity there was coated, in to microns thick (when dried), a mixture solution which was obtained by such a way that a 10 percent solution of nitrocellulose (RS-l, trade name, supplied by Daiseru, degree of nitration of 11.5 to 12.2 percent) in ethylalcohol-methylalcohol (7:3) was mixed with a 10 percent (by weight) solution of polyvinylpyrrolidone (PBP- K90, trade name, supplied by GAE Co.) in ethylalcohol-methylalcohol (7:3) at ratio of 2:8 (by weight) and an amount of methyl ethyl ketone which is one and a half the amount of the above mixture by weight was added to said mixture to form a barrier layer and dried.

Further, on the resulting barrier layer there was coated a photosensitive agent composed of poly-N- vinylcarbazole and Crystal Violet in benzenechlorobenzene (1:1) at 4 to 6 g./m. and dried.

The resulting photosensitive film was charged, exposed, and developed according to a conventional electrophotographic reproducing method to form clear visible images free from white points.

Example 5 On an aluminum plate (31 microns thick), conductive support, there was coated a mixture solution obtained in such a way that a 10 percent solution of nitrocellulose (RS 2, trade name, supplied by Daiseru, degree of nitration of 11.5 to 12.2 percent) was mixed with a 10 percent solution of polyvinylpyrrolidone (PBP-K90, trade name, supplied by GAF Co.) at ratio of 1:1 (by weight) both in ethylalcohol-methylalcohol (7:3 and amounts of methyl ethyl ketone and dimethylformamide each of which is one fourth the above mixture by weight, respectively was added to said mixture, at l to 2 microns thick (when dried) to form a barrier layer and dried. The resulting barrier layer was highly transparent, strong and flexible, and tightly adhered to the aluminum support. On the barrier layer there was coated a photosensitive agent composed of poly-N-vinylcarbazole 2 g., Rhodamine B 20 mg. and diphenyl chloride (Kanechlor, trade name, supplied by Kanegafuchi Kagaku Co.) as plasticizer in 40 ml. of benzene-chlorobenzene 1:1 to form a photosensitive layer of 9 microns thick. For the purpose of using as a master for electrophotography the resulting photosensitive plate was repeatedly subjected to an electrophotographic process which comprises corona-charging at 7.0 KV, exposing to a 500 W tungsten lamp at 40 lux. sec. and transferring the resulting electrostatic image to an electrostatic recording paper. When the electrostatic recording paper was developed with a liquid developer, the resulting image was excellent, and the effect of preventing discharge destroy was far better than conventional master having no barrier layer. The durable repeating number (the number of cycles that a photosensitive member may be sequentially charged, exposed, developed (if required) and transferred as a master for electrophotography without exhibiting fatigue phenomena) was as shown below.

Having no barrier about 100 times Having a barrier about 1500 times Example 6 A photosensitive plate prepared in a way similar to Example 5 was repeatedly subjected to a conventional xerographic process comprising charging at -7.0 KV, exposing a light pattern at about 100 lux. sec., developing with a liquid developer, transferring to an ordinary paper and cleaning the photosensitive plate. The sensitivity was excellent and the discharge destruction effect by the barrier layer was remarkable. The durable repeating number was as shown below.

Having no barrier about 50 times Having a barrier about 700 times Example 7 On an aluminum plate (31 microns thick), a conductive support, there was coated a mixture obtained by such a way that a 7 percent (by weight) solution of nitrocellulose (R840, trade name, supplied by Daiseru, degree of nitration 11.5 to 12.2 percent) was mixed with a 10 percent solution of polyvinylpyrrolidone (PBP-K30, trade name, supplied by GAF Co.) at ratio of 2:8 (by weight) both in ethylalcohol-methylalcohol (7:3), and an amount of methyl ethyl ketone, which is a half of the resulting mixture by weight, was added to said mixture, at 1 to 2 microns thick (when dried) to form a barrier layer and dried. This barrier layer had the same properties as those of Example 5.

On the barrier layer, there was coated a photosensitive agent composed of poly-n-vinylcarbazole 2g., and Crystal Violet 10 mg, and Coumarone RS /2 (trade name, supplied by Fuji Seitetsu) as plasticizer in 40 ml. of benzene-chlorobenzene (1:1) to form a photosensitive layer of about 8 microns thick. The resulting photosensitive plate was repeatedly subjected to a process for transferring an electrostatic image to an electrophotographic paper in a way similar to Example 5. The transferred electrostatic latent image was developed with a toner by a magnet brush method. The discharge destruction preventing effect was remarkable, and fatigue phenomenon was very little and the durable repeating number was as shown below.

Having no barrier layer about times Having a barrier layer about 1200 times Example 8 A photosensitive plate prepared in a way similar to Example 7 was repeatedly subjected to a conventional xerographic process comprising charging at -7.0 KV, exposing an image at lux. sec., developing by a cascade method, transferring to an ordinary paper and cleaning the photosensitive plate. It was found that the discharge destroy preventing effect was excellent. The durable repeating number was as shown below.

Having no barrier about 50 times Having a barrier about 700 times Example 9 On a support as used in Example 5 there was coated, in l to 2 microns thick when dried, a mixture obtained by such a way that a 12 percent solution of nitrocellulose (SS %a, trade name, supplied by Daiseru, degree of nitration of 10.7 to 11.9 percent) in ethylalcoholmethylalcohol (7:3) was mixed with a 10 percent solution of polyvinylpyrrolidone (PBP-90, trade name, supplied by GAF Co.) in the same solvent as above, at ratio 7:3 (by weight), and amounts of methyl ethyl ketone and dimethylformamide each of which is one fourth the above mixture by weight, respectively, was added to said mixture, to form a barrier layer and dried. The resulting barrier layer was highly transparent, strong and flexible, and furthermore, could tightly adhere to an aluminum base plate. On the barrier layer there was coated a photosensitive agent composed of 0.5 mole of chlorinated poly-N-vinylcarbazole 2 g., and 2,4,7-trinitrofluorenone 3.2 g., and diphenyl chloride as plasticizer in 40 ml. of tetrahydrofuran to form a Example An electrophotosensitive plate as used in Example 9 was repeatedly subjected to a xerographic process comprising charging at -7.0 KV, imagewise exposing at about 20 lux. sec., developing by a magnet brush method, transferring to an ordinary paper, and cleaning the photosensitive layer. The resulting image on the transferring paper was clear, and there was hardly observed the discharge destruction. The durable repeating number was as shown below.

Having no barrier about 200 times Having a barrier about 3000 times Example 1 I On a sandblasted aluminum plate (100 microns thick) as a conductive support there was coated, in l to 2 microns thick when dried, a mixture obtained by such a way that a 20 percent solution of nitrocellulose (RS-l/4, trade name, supplied by Daiseru, degree of nitration 11.5 to 12.2 percent) in a mixed solvent of ethylalcohol-methylalcohol (7:3) Was mixed with a 10 percent solution of polyvinylpyrrolidone (PEP-K90, trade name, supplied by GAF Co.) in the same solvent as above, at the ratio 1:1 (by weight), and amounts of methyl ethyl ketone and dimethylformamide each of which is one fourth the above mixture by weight, respectively was added to said mixture, to form a barrier layer and dried. The resulting barrier layer was highly strong and flexible, and furthermore, could tightly adhere to a support. On the barrier layer there was coated a photosensitive agent composed of poly-N vinylcarbazole 2 g., 2.4,5,7-tetranitrofluorenone 3.7 g., and 0.5 g. of diphenyl chloride (trade name, Kanechlor) in 40 ml. of tetrahydrofuran in about microns thick when dried. This photosensitive plate was repeatedly subjected to an electrostatic transferring method comprising charging at -7.0 KV, exposing to a light image at about 15 lux. sec. and transferring to an electrostaticrecording paper. The electrostatic recording paper was developed with a liquid developer. The discharge destruction preventing effect was remarkably improved. The durable repeating number was as shown below.

8 Having no barrier layer about 250 times Having a barrier layer about 3000 times Example 12 On a paper treated for imparting conductivity as a conductive support there was coated, in l to 2 microns thick when dried, a mixture obtained by such a way that a 10 percent solution of nitrocellulose (RS 2, trade name, supplied by Daiseru, degree of nitration of l 1.5 to 12.2 percent) in a mixed solvent of ethylalcoholmethylalcohol (7:3) was mixed with a 10 percent solution of polyvinylpyrrolidone (PBP-K60, trade name, supplied by GAF Co.) in the same solvent as above, at ratio of 3:7 (by weight), and an amount of methyl ethyl ketone which is a half of the resulting mixture by weight, was added to said mixture, to form a barrier layer and dried. The resulting barrier layer has film property similar to that of Example 5. On the barrier layer there was coated a photosensitive agent composed of 0.5 mole of chlorinated poly-N-vinylcarbazole 2 g., and 2,4,7-trinitrofluorenone 3.2 g., and 0.5 g. of diphenyl chloride as a plasticizer in 40 ml. of tetrahydrofuran at about 12 microns thick when dried.

The resulting photosensitive plate was repeatedly subjected to an electrostatic transferring process comprising charging at 7.0 KV, exposing to a light image at about 5 lux. sec., and transferring to an electrostatic recording paper. The electrostatic recording paper was developed by a magnet brush method to produce images of good quality. The discharge destruction preventing effect was also excellent. The durable repeating number was as shown below.

Having no barrier about 200 times Having a barrier about 4000 times Example 1 3 On a conductive member composed of polyester film microns thick) having an aluminum vapordeposited layer having a visible ray transmittance rate of 60 percent, there was coated, in l to 2 microns thick when dried, a mixture obtained by such a way that a 6 percent solution of nitrocellulose (RS-20, trade name, supplied by Daiseru, degree of nitration of l 1.5 to 12.2 percent) in a mixed solvent of ethylalcoholmethylalcohol (7:3) was mixed with a 10 percent solution of polyvinylpyrrolidone (PEP-K30, trade name, supplied by GAF Co.) in the same solvent as above, at ratio of 1:1 (by weight), and an amount of methyl ethyl ketone which is one fourth the resulting mixture by weight, was added to said mixture, to form a barrier layer and dried. This barrier layer had film property similar to that of Example 5. Further, on the barrier layer there was coated a photosensitive agent composed of poly-N-vinylcarbazole 2 g., Rhodamine B 20 mg., and diphenyl chloride as plasticizer in 40 ml. of benzene-chlorobenzene (1:1) to form a photosensitive layer of 10 microns thick when dried.

The resulting photosensitive member was repeatedly subjected to an electrostatic transferring method comprising charging at -7.0 KV, exposing a light image at about 50 lux. sec. and transferring to an electrostatic recording paper. The electrostatic recording paper was developed with a liquid developer. The discharge destruction preventing effect was remarkable.

Example 14 A 10 percent solution of nitrocellulose (RS-2, trade name, supplied by Daiseru, degree of nitration of 11.5 to 12.7 percent) in methyl ethyl ketone-methyl isobutyl ketone (6:4) was mixed with a percent solution of polyvinylpyrrolidone (PEP-K90, trade name, supplied by GAF Co.) in isopropanol-methanol (4:6) at ratio of 3:7 (by weight), and an amount of a mixed solvent of methyl ethyl ketone-dimethylformamide (1:1 which is a half of the resulting mixture by weight, was added to said mixture to obtain a transparent and low viscous liquid, as a solution for a barrier layer. Then, TiO was added to the above liquid at ratio of resin solid to TiO- 6:1, ball-milled for two days and filtered to obtain a coating solution. On a polycarbonate laminated support of aluminium foil therewas coated the resulting solution in 5 to 4 microns thick when dried to form a white barrier layer. The resulting coated film was highly strong adhesive and had a good hiding property.

Further, on the barrier layer there was coated a photosensitive agent composed of a solution of poly-N- vinylcarbazole, a trimethine dye, and a plasticizer such as Coumarone RS l/2, Coumarone LCR and chlorinated paraffin in toluene-monochlorobenzene (1:1) in 5 to 6 g./m. when dried to form a photosensitive plate.

The resulting photosensitive plate was subjected to charging by a known method and then loaded it in a conventional camera to take a photograph of an upper half figure of a man by exposing to a strobolight at a distance of 15 m. Removing the photosensitive plate out of the camera in a dark room when finished to photograph, it was developed with a liquid developer to obtain an excellent reflexion positive image of a man.

We claim:

1. An electrophotographic photosensitive member which comprises an electrically conductive support, a barrier layer overlying the electrically conductive support, the barrier layer comprising a blend of nitrocellulose and polyvinylpyrrolidone in which the ratio of nitrocellulose to polyvinylpyrrolidone is in the range of 2:8 to 8:2, by weight, and having a thickness of 1 to 10 microns and an organic photoconductive layer overlying the barrier layer.

2. An electrophotographic photosensitive member according to claim 1 in which the organic photoconductive layer is composed of organic polymeric photoconductive material.

3. An electrophotographic photosensitive member according to claim 2 in which the organic polymeric photoconductive material is an organic photoconductive material selected from the group consisting of poly-N-vinylcarbazole, chlorinated poly-N- vinylcarbazole, brominated poly-N-vinylcarbazole, cyanated poly-N-vinyl-carbazole, and polyvinylacenaphthene.

Claims

1. AN ELECTROPHOTOGRAPHIC PHOTOSENSITIVE MEMBER WHICH COMPRISES AN ELECTRICALLY CONDUCTIVE SUPPORT, A BARRIER LAYER OVERLYING THE ELECTRICALLY CONDUCTIVE SUPPORT, THE BARRIER LAYER COMPRISING A BLEND OF NITROCELLULOSE AND POLYVINYLPYRROLIDONE IS IN WJIHICH THE RATIO OF NITROCELLULOSE TO POLYVINYLPYRROLIDONE IS IN THE RANGE OF 2:8 TO 8:2, BY WEIGHT, AND HAVING A THICKNESS OF 1 TO 10 MICRONS AND AN ORGANIC PHOTOCONDUCTIVE LAYER OVERLYING THE BARRIER LAYER.

3. An electrophotographic photosensitive member according to claim 2 in which the organic polymeric photoconductive material is an organic photoconductive material selected from the group consisting of poly-N-vinylcarbazole, chlorinated poly-N-vinylcarbazole, brominated poly-N-vinylcarbazole, cyanated poly-N-vinyl-carbazole, and polyvinylacenaphthene.