JPS61254953A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To enable a good image to be formed, especially, even under low temp. and low humidity by forming an undercoat contg. an electrostatic charge transfer polymer complex composed of polyvinylpyridine and an electron acceptor having a specified value or more of electron affinity on the conductive substrate of an electrophotographic sensitive body. CONSTITUTION:The undercoat formed on the conductive substrate contains the electrostatic charge transfer polymer complex composed of polyvinlpyridine and an electron acceptor having an electron affinity of >=0.5eV, such as p- benzoquinone represented by the formula shown on the right, and it may be formed by using only said complex without using a binder. On this undercoat, a charge generating layer and a charge transfer layer are successively laminated to form a photosensitive layer, thus permitting the obtained electrophotographic sensitive body to be restrained in rise of potential in the light and variation of potential in the dark even at the time of repeated uses by using such a stable acceptor complex, and a superior image to be formed even under low temp. and low humidity.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electrophotographic photoreceptor, and more particularly to an electrophotographic photoreceptor provided with an undercoat layer that functions as an adhesive layer and a barrier layer.

Generally, Carlson type electrophotographic photoreceptors are charged with
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. However, a photosensitive layer has been proposed that has the following layer structure, with functions separated into a charge generation layer and a charge transport layer.
Generally, the charge generation layer is a very thin layer on the conductive layer, e.g.
．． Since the thickness is about 5 μm, very slight defects, dirt, deposits, scratches, etc. on the substrate surface affect the uniformity of the thickness of the charge generation layer.

Since nonuniform thickness of the charge generation layer may cause uneven sensitivity of the photoreceptor, 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 broken urethane, polyamide, polyvinyl alcohol, epoxy resin, casein, methylcellulose, nitrocellulose, or phenolic resin as a layer between the photosensitive layer and the conductive layer. When the photoreceptor used is used repeatedly, it tends to cause an increase in the bright area potential and a fluctuation in the dark area potential, and the increase in the bright area potential is particularly noticeable in low temperature and low humidity environments. It has the disadvantage that it cannot be obtained.

[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 after repeated use, and provides good image quality even under low temperature and low humidity conditions.

[Means for solving problems]

According to the present invention, in an electrophotographic photoreceptor having at least an undercoat layer and a photosensitive layer on a substrate, the core undercoat layer transfers polymer charge between polyvinylpyridine and an accessor compound having an electron affinity of 0.5 eV or more. An electrophotographic photoreceptor specially designed to contain a complex is provided.

Conventionally, ionic conductivity plays an important role in the electrical conductivity of the resins mentioned above used in the undercoat layer, but at low temperatures and low humidity, the electrical conductivity decreases and the carriers are efficiently charged. It is thought that because the light is separated and no longer escapes to the substrate side, the bright area potential increases and the dark area potential fluctuates.

Therefore, if a polymeric charge transfer complex is contained in the undercoat layer as in the present invention, carriers generated in the photosensitive layer can be efficiently separated and easily released to the substrate side even under low temperature and low humidity. This is thought to suppress the increase in bright area potential.

Conventionally, attempts have been made to achieve a similar effect by adding acceptor compounds to the undercoat layer, but in both cases it is clear that the acceptor compound is a polymeric substance that is the main component of the undercoat layer. There are few cases in which a charge transfer complex is formed, and even if a charge transfer complex is formed, the stability of the complex is poor.
In many cases, the effect was not stably expressed because the complex was decomposed due to heat drying or changes over time during the production of the photoreceptor, and the added acceptor compound volatilized.

In contrast, the I-divinylpyridines used in the present invention exhibit strong electron donating properties and form very stable complexes with acceptor compounds.

Various combinations of polyvinylpyridine and acceptor compounds are possible, but in the present invention, since formation of a stable complex is desired, Iso-4-vinylpyridine is preferred as polyvinylpyridine, and As an acceptor compound with an electron affinity of 0.5 eV or more, P-benzoquinone (electron affinity 0.77 eV)
, chloranil and the like are preferred. The reaction between poly-4-vinylpyridine and P-benzoquinone is as follows:
The complex formation reaction is carried out by mixing at room temperature.

The ratio of the hazardous accelerator compound to the vinyl pyridine unit is preferably 1 mol% to 50 mol%. vs. 10-100
It may be contained in an amount of 50%. The thickness of the undercoat layer is preferably 0.1 to 10.0 μm, particularly 0.5 to 5.0 μm. For coating, dip coating, spray coating, and roll coach coating methods are used.

In the case of a functionally separated photosensitive layer, the charge generation layer may contain azo pigments such as Sudan Red, Guianpuru, and Jenas Green B-nato, quinone pigments such as Algol Yellow, Pyrenequinone, and Indanthrene Brilliant Violet RRP, quinocyanine pigments, perylene pigments, indigo pigments, Indigo pigments such as thioindigo, bisbenzimidazole pigments such as Indo First Orange Toner, 7-thalocyanine pigments such as copper phthalocyanine, and charge-generating substances such as quinacridone pigments are combined with poly(lipinylbutyral, poly, tyrene, etc.).
It can be formed by dispersing it in a binder resin such as polyvinyl chloride, polyvinyl acetate, acrylic, pyrrolidone, methylcellulose, hydroxypropylmethylcellulose, and coating this dispersion on the above-mentioned subbing layer. . The thickness of such a charge generation layer is suitably 5 microns or less, preferably 0.01 micron to 1 micron.

The charge transport layer provided on the charge generation layer contains a polycyclic aromatic compound such as anthracene, pyrene, phenanthrene, coronene, etc., or indole, carbazole, oxazole, inoxazole, thiazole, imidazole, pyrazole, oxadiazole, etc. in the main chain or side chain. It is formed by dissolving a charge transporting substance such as a compound having a nitrogen-containing cyclic structure such as azole, pyrazoline, thiadiazole, or triazole, or a hydrazone compound 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. Such resins include polyester, polysulfone, polycargenate, polymethacrylic acid ester, etc. Examples include listyrene. The thickness of the charge transport layer is approximately 5 to 20 microns.

, the single-layer photosensitive layer used in the present invention, for example, C
Examples include a dS or ZuO resin dispersion layer, an organic photoconductive polymer layer such as poly-N-vinylcarbazole or polyvinylanthracene, a selenium vapor deposition layer, a selenium-tellurium vapor deposition layer, or an amorphous silicon layer.

The substrate used in the photoreceptor of the present invention is a conductive! ! Any substrate may be used as long as it has a layer, and specific examples include aluminum, steel, vanadium, molybdenum,
Chromium, nickel, titanium, zinc, indium, brass, etc. molded into drums or sheets, metal foils such as aluminum and steel laminated to plastic films, aluminum, indium oxide, tin oxide, etc. made into plastic films. Examples include vapor-deposited materials, or plastic films and paper whose surfaces are conductive-treated by applying a conductive material such as metal powder, carbon black, iodized steel, or polymer electrolyte material together with a suitable binder resin.

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

Next, the present invention will be further explained using examples.

Example 10 g of poly-4-vinylpyridine (manufactured by Koei Chemical Co., Ltd.) was mixed with MeO
H1001, BuOH1001! P-benzoquinone (II) was further added to prepare the undercoat layer coating solution.

As a substrate, the above-mentioned undercoat layer paint was coated by dip coating on an aluminum cylinder of 60 φ x 260 m to a film thickness of 2.0 μm, and dried at 60° C. for 30 minutes. Next, 10 parts of a disazo pigment with the following structure was added to cellulose acetate butyrate resin (commercial 2
6 parts of product name: CAB-381 (manufactured by Eastman Chemical) and 60 parts of cyclohexanone were dispersed for 20 hours in a sand mill apparatus using 1-rubbed beads. 100 parts of methyl ethyl ketone was added to this dispersion, and the mixture was applied by dip coating onto the undercoat layer, and dried by heating at 100°C for 10 minutes.
The ratio of forming a charge generation layer with a coating amount of "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 Seitetsu Kagaku Co., Ltd.) were dissolved in 80 parts of toluene. This liquid was applied onto the charge generation layer and dried with hot air at 100° C. for 1 hour to form a charge transport layer with a thickness of 16 μm.

The electrophotographic photoreceptor thus produced was heated to -5,6K
It is installed in an electrophotographic copying machine that has V corona charging, image exposure, dry toner development, toner transfer to plain paper, and cleaning process using urethane rubber grade (hardness 70°, pressure 10 gw/cms, angle 20@ to the photoreceptor), etc. ) to evaluate the electrophotographic properties. Low temperature/low humidity environment (15℃/
When Iooo images were taken continuously under R, H, 10 cm), very stable images were obtained with no rise in bright area potential.

Claims (3)

[Claims] (1) An electrophotographic photoreceptor comprising at least an undercoat layer and a photosensitive layer on a substrate, the undercoat layer comprising a polymeric charge transfer complex of polyvinylpyridine and an acceptor compound having an electron affinity of 0.5 eV or more. An electrophotographic photoreceptor characterized by containing (2) The electrophotographic photoreceptor according to claim 1, wherein the undercoat layer is composed only of the polymer charge transfer complex. (3) The electrophotographic photoreceptor according to claim 1, wherein the acceptor compound is parabenzoquinone or chloranil.