JPS61254952A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To restrain rise of potential in the light and fluctuation of potential in the dark even at the time of repeated uses, and to obtain an electrophotographic sensitive body capable of forming a stable image by forming an undercoat contg. a polymer compd. having viologen structures on a substrate and laminating a photosensitive layer on it. CONSTITUTION:The undercoat is formed by coating the conductive substrate with a dimethylformamide soln. of a polymer compd. obtained by reacting viologen, that is, 1,1'-dialkyl-4,4'-bipyridinium with an acrylonitrile- chloromethylstyrene copolymer, and drying it, and a photoconductive layer is formed by successively laminating an electrostatic charge generating layer and a charge transfer layer on the undercoat, thus permitting the undercoat to be given functions as adhesive and barrier layers, and consequently, the obtained photosensitive layer to easily carry electrons generated in the photoconductive layer even under low temp. and low humidity to the side of the substrate and to form a stable image suitable for use in laser printers and the like without rise of potential in the light.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an electrophotographic photoreceptor, and more particularly to an electrophotographic photoreceptor in which an undercoat layer having functions as an adhesive layer and a barrier layer is provided on a substrate. It is.

[Prior art]

General K, Carlson type electrophotographic photoreceptors are charged -
In order to form an image with a constant image density and no background smudge upon repeated exposure, the stability of the dark area potential and the bright area potential is important. For this reason, it has been proposed to provide a layer having the function of a barrier layer between the photosensitive layer and the conductive layer. In addition, a layered structure in which the photosensitive layer is functionally separated into a charge generation layer and a charge transport layer has been proposed, but generally the charge generation layer is an extremely thin layer on the conductive layer, for example,
Since the thickness of the charge generating layer is approximately .mu., very slight defects, dirt, deposits, scratches, etc. on the surface of the substrate cause the thickness of the charge generation layer to be non-uniform. If the thickness of the charge generation layer is non-uniform, uneven sensitivity will occur in the photoreceptor, so it is required that the thickness of the charge generation layer be made as uniform as possible. For this reason, it has been proposed to provide an undercoat layer between the charge generation layer and the conductive layer, which functions as a barrier layer and an adhesive layer.

Until now, it has been known to use polyurethane, polyamide, polyvinyl alcohol, epoxy I [4 fat, casein, methylcellulose, nitrocellulose, or phenolic resin] as a layer between the photosensitive layer and the conductive layer. Photoreceptors using this layer as an undercoat layer tend to cause increases in bright area potential and fluctuations in dark area potential after repeated use.Especially in low temperature and low humidity environments, the increase in bright area potential is significant, and it is difficult to continuously It has the disadvantage that when used as a copy, it is not possible to obtain copies with a certain level of image quality.

[Problem that the invention seeks to solve]

SUMMARY OF THE INVENTION An object of the present invention is to provide an electrophotographic photoreceptor that suppresses increases in bright area potential and fluctuations in dark area potential even when used repeatedly.

[Means for solving problems]

According to the present invention, in an electrophotographic photoreceptor in which at least an undercoat layer and a photosensitive layer are provided on a substrate, the undercoat layer is a polymer compound having a viologen (1,1'-dialkyl-4,4'-bipyridinium) structure. An electrophotographic photoreceptor characterized by containing the following is provided.

Biolodan used in the present invention is known to have reversible redox ability and function as an electron transfer catalyst.When formed into a film, the redox reaction proceeds through the film. It has been reported that

Ionic conductivity plays an important role in the electrical conductivity of the above-mentioned resins conventionally used in the undercoat layer, but at low temperatures and low humidity, the electrical conductivity decreases and the carriers generated in the photosensitive layer are efficiently charge-separated and transferred to the substrate. It is thought that because the light cannot escape to the side, the bright area potential increases and the dark area potential fluctuates.

In the present invention, by introducing the above-mentioned viologen structure having electron transport properties into the undercoat layer, it is possible to
In the case of an electrophotographic process in which holes are moved as property carriers, electrons generated in the photosensitive layer can be easily released to the base side, which is thought to suppress an increase in bright area potential.

Various reactions have been proposed as a method for introducing a viologen structure into a polymer compound. For example, acrylonitrile-700 methylstyrene copolymer and 4,4'-
A method of mixing with bipyridyl and heating and stirring at 60° C. for 30 minutes to 1 hour is mentioned.

Still another method is to mix poly γ-methyl-D-glutamate and 1-propyl-4-(4-pyridyl)pyridinium bromide and to prepare the mixture at 60°C to 100°C.
Heat and stir for 0 minutes to 1 hour.

When an acrylonitrile-chloromethylstyrene copolymer is used as the polymer compound of the undercoat layer, the viologen content is 1 mol % to 50 mol % based on the chloromethyl styrene unit, depending on the copolymerization ratio of chloromethyl styrene. A ratio of . The thickness of the undercoat layer is 0.1 to 10
．． 0μ, particularly 0.5 to 5.0μ, is preferred and can be coated by dip coating, sougere coating, or roll coating.

In the present invention, the photosensitive layer may be of a single layer type or of a laminated structure type in which the charge generation layer and the charge transport layer are separated in function.

The charge generation layer is made of azo pigments such as Sudan Red, Diane Glue, and Jenas Green B, Algol Yellow,
Quinone pigments such as pyrenequinone and indanthrene brilliant violet RRP, quinocyanine pigments, (rylene pigments, insogo pigments such as indigo and thioindigo, bisbenzimidazole pigments such as India First Orange toner, heptalocyanine pigments such as phthalocyanine, quinacridone pigments, etc.) The charge-generating material is dispersed in a binder resin such as polyvinyl butyral, polystyrene, polyvinyl chloride, polyvinyl acetate, acrylic, polyvinylpyrrolidone, methylcellulose, hydroxypropyl methylcellulose, etc., and this dispersion is applied to the subbing layer described above. It can be formed by coating on top.

The thickness of such a charge generation layer is 5μ or less, preferably o
, oiμ to 1μ is appropriate.

The charge transport layer provided on the charge generation layer has a main chain or C side a.
Polycyclic aromatic compounds such as K anthracene, pyrene, phenanthrene, coronene, or indole, carbazole,
Oxazole, inoxazole, thiazole, imidazole, pyrazole, oxadiazole, pyrazoline,
It is formed using a coating liquid in which a charge-transporting substance such as a nitrogen-containing cyclic compound such as cyanoazole or doriapur, or a hydrazone compound is dissolved in a film-forming resin. This is because the charge transporting substance generally has a low molecular weight and has poor film-forming properties by itself. Examples of the strong resin include polyester, polysulfone, polycargonate, polymethacrylic acid esters, polystyrene, and the like.

The thickness of the charge transport layer is approximately 5 to 20 microns.

The photosensitive layer used in the present invention includes the above-mentioned photosensitive layers.
One layer of organic photoconductive polymer such as N-vinylcarbazole or polyvinylanthracene, selenium vapor deposited layer, selenium
Examples include a tellurium vapor deposited layer and an amorphous silicon layer.

The substrate used in the photoreceptor of the present invention may be any substrate as long as it has a conductive layer, and specific substrates include:
For example, aluminum, copper, vanadium, molybdenum, chromium, nickel, titanium, zinc, indium, brass, etc. molded into drums or sheets, metal foils such as aluminum or copper laminated onto plastic films, aluminum, indium oxide, etc. , tin oxide, etc., deposited on a glass film, or a plastic film whose surface is conductive-treated by coating a conductive substance such as metal powder, carbon blank, iodized steel, or polymer electrolyte together with a suitable adhesive resin. Examples include paper.

The electrophotographic photoreceptor of the present invention can be used not only in electrophotographic copying machines, but also in radar printers, CRT printers, electrophotographic plate-making systems, and the like.

Next, the present invention will be explained in more detail with reference to Examples.

〔Example〕

Copolymer of acrylonitrile and chloromethylstyrene (
Copolymerization ratio of chloromethylstyrene: 15rnol 10
g was dissolved in dimethylformamide (DIP) 2001, and 4,4'-bivitrite of o and sg were further added to prepare a coating solution for an undercoat layer.

The above-mentioned undercoat layer paint was dip-coated to a film thickness of 2.0 μm as desired onto an aluminum cylinder of 60φ×260μ as a substrate, and dried at 60° C. for 30 minutes.

Next, 10 parts of a disazo pigment having the following structure, 6 parts of cellulose acetate butyrate resin (trade name: CAB-381; Eastman Chemicals), and 760 parts of cyclohexano were dispersed for 20 hours in a sand mill apparatus using lφ rast beads. 100 parts of methyl ethyl ketone was added to this dispersion, which was applied onto the undercoat layer by dip coating, and dried by heating at 100°C for 10 minutes to form a charge generating layer with a coating weight of 0.1.97 m''.

Next, 10 parts of a hydrazone compound having the following structural formula and 15 parts of a styrene-methyl methacrylate copolymer resin (trade name: MS200, manufactured by Tetsutsu Kagaku ■) were mixed with 80 parts of toluene.
It was dissolved in parts. Apply this solution on the charge generation layer and
Hot air drying was performed at 00° C. for 1 hour to form a charge transport layer with a thickness of 16 μm.

The electrophotographic photoreceptor produced in this way was -5,6k
An electrophotographic copying machine that has Vfluoro charging, image exposure, dry toner development, toner transfer to plain paper, and a cleaning process using a urethane rubber blade (hardness 70°, pressure 10 gvr/cm, angle 20° to the photoreceptor), etc. It was installed and the electrophotographic characteristics were evaluated.

When 1000 images were continuously produced under a low temperature and low humidity environment (15° C./10%), very stable images were obtained with no increase in bright area potential.

Claims (1)

[Claims] In an electrophotographic photoreceptor in which at least an undercoat layer and a photosensitive layer are provided on a substrate, the undercoat layer is made of viologen (1,1'-
An electrophotographic photoreceptor characterized by containing a polymer compound having a dialkyl-4,4'-bipyridinium) structure.