JPH02222965A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To form an intermediate layer which maintains a low resistance characteristic and to stabilize characteristics in all atmospheres by incorporating iodine into an intermediate layer which blocks overcurrent between a conductive base body and a photosensitive layer. CONSTITUTION:Halogen, particularly the iodine as the representative example of the halogen is incorporated into the intermediate layer 2 between the conductive base body 1 and the photosensitive layer 3. The addition of the halogen, more particularly the iodine to the intermediate layer 2 corresponds to the dispersion of electrons having an exceedingly high electron cloud density into the structure; in addition, the increase of the electron density in the material coupled with the strong electronegativity of the iodine lead to a decrease in resistance. The intermediate layer added with the iodine takes both of the factor to lower the resistance of moisture sensitiveness and the factor to lower the resistance of non-moisture sensitiveness into acquisition and maintains the low resistance regardless of the atmosphere humidity. The characteristics of the photosensitive body having the intermediate layer are stabilized in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Object of the Invention (Field of Industrial Application) The present invention relates to an electrophotographic photoreceptor that is employed in, for example, copying machines, printers, etc., and forms a latent latent image on its surface.

(Prior art) In conventional copiers, printers, etc., photoreceptors are made by vapor deposition method or coating method, and even photoreceptors made by coating method use a single photosensitive layer. There are also those that use multiple photosensitive layers. Most of the photoreceptors manufactured by the coating method have a thin, low-resistance intermediate layer between a photosensitive layer and a conductive substrate that supports the photosensitive layer. The role of this intermediate layer is to block excessive current flow and prevent deterioration of the photosensitive layer over its entire surface or locally. The selection of the intermediate layer is particularly important when the conductive support is metal or when the photosensitive fine powder in the photosensitive layer has coarse particles. If the intermediate layer is inappropriate, local defects will occur, resulting in so-called plots or a decrease in sensitivity. Since the role of the intermediate layer is as described above, the resistance value preferably used is 10aΩ-eI11~101! It is about Ω-country. Examples of resistors that have been favorably used in the past include casein, polyvinyl butyral, and certain nylons, all of which are characterized by containing a large amount of OH groups. The presence of OH groups imparts water absorption to the intermediate layer, and the action of adsorbed water ensures an appropriate reduction in resistance. Even when other materials are used, in most cases the lower resistance due to adsorbed moisture is utilized.

(Problem to be Solved by the Invention) However, since the intermediate layer as described above maintains low resistance depending on the balance of adsorbed water, the amount of adsorbed water decreases in an extremely low humidity atmosphere. As a result, resistance increases, which obstructs the photocurrent that should flow to the photoreceptor, causing a decrease in sensitivity and an increase in residual potential.

Configuration of the Invention (Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention has a configuration in which a halogen is contained in the intermediate layer between the conductive substrate and the photosensitive layer. In particular, a typical example of a halogen is iodine.

(Function) Adding halogen, especially iodine, to the intermediate layer corresponds to dispersing atoms (or molecules) with extremely high electron cloud density in the structure.

The increase in electron density within the material, combined with the strong erectronegativity of iodine, causes a decrease in resistance.

:Example) First, conductive substrate 1, for example, a smooth aluminum cylindrical surface with a diameter of 80φ, is coated with iodine as intermediate layer 2 using, for example, a coating liquid with the following composition, so that the thickness after completely drying is 1μ. It was constructed by coating a thin layer of polymeric material containing the material.

Composition l 0M8000 10gr (manufactured by Toyo Rayon Co., Ltd., nylon resin) Ethyl alcohol 81gr Toluene
9grl,
The Igr coating method is a type of dipping method, and drying was performed at room temperature. On top of the completed intermediate layer, a photosensitive layer 3 using a finely powdered photoreceptor is further coated using, for example, a photosensitive coating liquid of the second composition so that the thickness after complete drying is 16 μm. did.

Composition 2 α type steel phthalocyanine 10.6 grP −
64536,75gr (manufactured by Mitsui Toatsu Co., Ltd., polyester resin) Kneepan 20-H813,8gr (manufactured by Mitsui Toatsu Co., Ltd., melamine resin) Microhexanone 170 grThe coating liquid with the above composition was sufficiently mechanically mixed before use. . The processed photosensitive layer 3 was dried at room temperature or at a low salt temperature, and when most of the microhexanone had evaporated, it was heated in a cold oven at 150° C. for 2 hours to complete the crosslinking of the polyester and melamine.

When the resulting photoreceptor was used in place of a 5eAs photoreceptor in a printer using a commercially available 5eAsl photoreceptor, very good images were obtained. +550 in dark areas of light image
A latent image of +15V was obtained in the bright part of the photoimage, and the image quality visualized by the normal development method was much sharper than when using the 5eAs photoreceptor.

To check humidity resistance, from 15°C8%RH to 35°C80
Tests were conducted by changing the atmosphere up to %RH, but no significant change was observed in the image forming characteristics. Particularly in low temperature and low humidity conditions, the product was left to stand for a sufficiently long period of time, and was operated and carefully tested, but no major changes in characteristics were observed.

In order to clarify the function of iodine in the examples, a photoreceptor from which only iodine was removed was prepared as a reference example, and its characteristics were investigated.

Reference Example: Using the same aluminum cylinder as in Example, using the first coating liquid with iodine removed, and making the intermediate layer 1μ thick, the first coating had the same composition as Example 2. The solution was applied to the surface of the intermediate layer, and after completely drying in the same manner as in Example 1,
A photosensitive layer with a thickness of μ was formed and heated to obtain a photoreceptor. This photoreceptor behaved differently from the photoreceptor made in the example, and firstly, the photoreceptor did not work immediately after fabrication. The details of the malfunction were extremely low sensitivity and extremely large reciprocal potential. This malfunction occurred when the photoconductor regained its 0-order operation after being left in a room at room temperature and humidity for more than 72 hours at 15°C.
%RH to 35° C. and 80% RH. As a result, poor operation was observed at low temperature and low humidity. The first cause of malfunction is an increase in the reciprocal potential.To give an example, the reciprocal potential in an atmosphere of 60% at 25°C was approximately 25V, but in an atmosphere of 15°C and CB%, the reciprocal potential increased to 250 volts. Reached. Sensitivity also appeared to be decreasing. Practically speaking, the limit that could be guaranteed was about 30% at 15°C.

As is clear from the numerical values of the reference example, the intermediate layer of the reference example loses adsorbed water in a low-humidity atmosphere and loses its usefulness as a low-resistance layer. Therefore, it is thought that the photocurrent was limited and malfunction occurred.

Note that the materials containing OH groups that have been used as the intermediate layer 2 are soluble in alcohol in most cases, and their solubility in other solvents is often very low. When coating photosensitive layers in layers after coating has dried, there is a technical issue in which the previously coated intermediate layer is not affected by the coating liquid for the photosensitive layer, which uses a non-alcoholic and often non-hydrophilic solvent. This is an important point.

Of course, if it becomes blue and the intermediate layer is contaminated by the coating liquid of the next superposed photosensitive layer, it will not work as a photoreceptor. on the other hand! is well soluble in alcohol. Therefore, it is easy to uniformly distribute the concentration in the material forming the intermediate layer.

Adding halogen, especially iodine, to the intermediate layer corresponds to dispersing atoms (or molecules) with extremely high electron cloud density in the structure.

The increased electron density within the material, combined with the strong eroctronegativity of iodine, causes a decrease in resistance.

More importantly, the way the resistance decreases in this case is unrelated to moisture. Therefore, the intermediate layer to which iodine is added has both a moisture-sensitive resistance-reducing factor and a non-moisture-sensitive resistance-reducing factor, and maintains low resistance regardless of atmospheric humidity. The properties of are stable.

The purpose of the present invention is to impart humidity stability to the material by simply adding iodine to it, without changing the material conventionally used for the intermediate layer 2. . There is no need to change the material of the intermediate layer 2 in order to add iodine; of course, there is a method of incorporating iodine into a polymer material that does not have OH groups, and this would be effective in lowering the resistance of the material. However, even if such complicated measures are taken, no effect beyond the above can be expected.

In this embodiment, the intermediate layer 2 containing iodine has been described, but the above-mentioned effects can be expected from halogen.

However, since low-mass halogens below bromine are difficult to handle and unstable, it is most suitable to use iodine from a practical technical point of view.

Furthermore, as a result of a separate test, in an example of 0M8000 with iodine added, even if the thickness of the intermediate layer was 5 μm, no large change in characteristics occurred and it was practical, and the amount of iodine added was 1% or more with respect to CM8000. If so, it is sufficiently effective. Furthermore, iodine addition has similar effects on casein and other materials.

C1 As described in detail, according to the present invention, by containing iodine in the intermediate layer provided between the conductive substrate and the photosensitive layer for the purpose of preventing overcurrent, it is possible to easily operate in a low humidity atmosphere. It can be used as an intermediate layer that maintains the low resistance characteristics required even in various environments, and provides an electrophotographic photoreceptor that is stable in all atmospheres.

[Brief explanation of the drawing]

The figure conceptually shows an embodiment of the present invention. ・Conductive substrate middle class ・Photosensitive layer

Claims (2)

[Claims] (1) An electrophotographic photoreceptor characterized in that a halogen-containing intermediate layer is provided between a conductive substrate and a photosensitive layer. (2) An electrophotographic photoreceptor characterized in that an intermediate layer containing iodine is provided between the conductive substrate and the photosensitive layer.