JP2000010303A - Electrophotographic photoreceptor and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the toner filming on a drum surface and the generation of black point on an image by preventing the waterdrop trace by dew condensation on the surface of a photosensitive layer. SOLUTION: In order to prevent the dew condensation on the top surface of a photosensitive layer, it is necessary to set the photosensitive layer surface temperature higher than the dew point of application environment in the formation of the photosensitive layer. As a suitable method for suppressing the temperature reduction of the photosensitive layer surface by evaporation heat of a solvent, for example, the solid component ratio of an applying solution is increased, and the solvent quantity remaining in the photosensitive layer is reduced; or the surface temperature of the photosensitive layer in the application is controlled to the dew point of the application environment or higher; or the photoreceptor base under application is heated. The conductive base is formed of aluminum alloy, other metallic materials, or resin, film or paper to which conductivity is imparted, and the photosensitive layer is formed on the conductive base. The charge generating material consists of an organic pigment conductive material such as phthalocyanine pigment, azo pigment or the like. The charge transport layer is formed by applying, for example, a hydrazone or enamine compound together with polyester resin as a solution.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photoreceptor (hereinafter, also simply referred to as "photoreceptor") mounted on an electrophotographic application apparatus using the Carlson method, such as a copying machine, a printer, and a facsimile, and a manufacturing method thereof. Regarding the method, in particular,
The present invention relates to an organic photoreceptor for electrophotography which prevents toner filming on a drum surface and black spots on an image, and a method of manufacturing the same.

[0002]

2. Description of the Related Art Many photoconductors used in the above-mentioned electrophotographic application apparatuses use inorganic photoconductive materials such as selenium, selenium alloys, zinc oxide and cadmium sulfide. However, recently, photoconductors using an organic photoconductive material have been actively developed, taking advantage of their non-polluting properties, film-forming properties, and light weight. Above all, a so-called function-separated type organic photoreceptor in which the charge generation layer and the charge transport layer are separated, the sensitivity can be greatly improved by forming each layer with a material optimal for each function, In addition, there are many advantages such as the spectral sensitivity can be set according to the wavelength of the desired exposure light.

[0003]

Many of the functionally separated organic photoconductors that are currently in practical use are of the negative charge type in which a charge generation layer and a charge transport layer are laminated in this order on a conductive substrate. It is. In the production of such a photoreceptor, first, a charge generation material is dispersed in a solvent together with a resin binder, and a dissolved coating solution is formed on a conductive substrate by a dip coating method.
Next, this is dried to form a charge generation layer. Next, a coating solution in which a charge transport material is dissolved together with a binder in a solvent is formed on the charge generation layer by a dip coating method, and dried.

[0004] It has been found that the photoreceptor having the organic photosensitive layer laminated in this manner has a problem that toner filming occurs particularly on the drum surface and black spots occur on an image.

Accordingly, an object of the present invention is to prevent toner filming on the drum surface and occurrence of black spots on an image in an organic photoreceptor for electrophotography in which a photosensitive layer is formed by a dip coating method.

[0006]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result have obtained the following knowledge. That is, since the layer (charge transport layer), which is the outermost surface of the organic photosensitive layer laminated as described above, requires printing durability, its thickness is usually 10 to 40 μm. If the film thickness is so large, a residual solvent will be present in the film during dip coating. As a result, due to the heat of vaporization when the residual solvent is volatilized, the temperature of the conductive substrate decreases, and the temperature of the conductive substrate becomes lower than the dew point of the coating environment. Remains on the outermost surface of the photosensitive layer. The trace of dew condensation had a size of about 0.1 to 10 μm, which could be observed by enlarging with an optical microscope. Based on this finding, the present inventor believes that the presence of this dew mark on the surface of the photosensitive layer causes the toner component to be present in the pores, that is, black spots on the image and toner filming on the drum surface occur. The inventors have found that the above object can be achieved when the surface is prevented from leaving a trace of water droplets due to dew condensation, and have completed the present invention.

That is, in the electrophotographic photoreceptor of the present invention, in an electrophotographic organic photoreceptor manufactured by forming a photosensitive layer by a dip coating method, water droplets due to condensation formed on the outermost surface of the photosensitive layer when the photosensitive layer is formed. It is characterized by having no trace.

The present invention also relates to the method of manufacturing a photoreceptor for electrophotography, wherein the solid content ratio of the coating solution by the dip coating method is adjusted by evaporating the coating solution so that the temperature of the substrate is reduced by the dew point of the coating environment. It is characterized in that the ratio is increased up to the following value.

Further, the present invention is a method of manufacturing a photoreceptor for electrophotography, characterized in that the surface temperature of the photosensitive layer during coating by the dip coating method is controlled to be equal to or higher than the dew point of the coating environment.

Further, the present invention provides a method of manufacturing a photoreceptor for electrophotography, wherein the photoreceptor substrate is heated during application by a dip coating method.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to prevent dew condensation on the outermost surface of the photosensitive layer, the surface temperature of the photosensitive layer needs to be higher than the dew point of the coating environment when the photosensitive layer is formed. However, heretofore, the surface temperature of the photosensitive layer has dropped below the dew point due to heat of vaporization of the solvent when forming the photosensitive layer by coating, and dew condensation has occurred on the outermost surface of the photosensitive layer. Therefore, in order to prevent such dew condensation, it is only necessary to suppress a decrease in the temperature of the photosensitive layer surface due to heat of vaporization of the solvent. Examples of suitable methods include, for example, increasing the solid content ratio of the coating solution, reducing the amount of solvent remaining in the photosensitive layer, controlling the surface temperature of the photosensitive layer at the time of coating to be equal to or higher than the dew point of the coating environment, and coating. Heating the inner photosensitive body substrate, or using a solvent having a high vapor pressure and a high boiling point. When the solvent shown in the following is used, it is necessary that the solvent has good compatibility with the photosensitive material.

The photoreceptor of the present invention is not particularly limited in its constitution and materials used except that there is no trace of water droplets on the outermost surface of the photosensitive layer by the above-mentioned method. Etc. can be adopted.

For the conductive substrate, known aluminum alloys such as JIS3003, JIS5000,
An IS6000 type or the like, another metal material, a resin imparted with conductivity, a film, paper, or the like can be used.

These conductive substrates are finished to a predetermined dimensional accuracy by extruding or drawing a metal material or by injection molding of a resin. The surface of the conductive substrate may be finished to an appropriate surface roughness by cutting with a diamond tool or the like as necessary, or may be left uncut as necessary. Thereafter, cleaning is performed to remove the cutting oil or the like used in the drawing process or the cutting process and obtain a clean conductive substrate surface. In this case, a conventional chlorinated organic solvent such as trichlene or chlorofluorocarbon or an aqueous cleaning such as a weak alkaline detergent is used.

Most of the function-separated organic photoreceptors are obtained by laminating a charge generation layer and a charge transport layer on a conductive substrate in this order. These photosensitive layers are formed on a conductive substrate, and if necessary, an undercoat layer having both a barrier function against injected charges and a function of improving adhesion can be provided between the conductive substrate and the charge generation layer. The undercoat layer is formed of polyvinyl alcohol, polyamide, polyurethane, melamine resin, phenol resin, aluminum oxide, or the like. The thickness of the intermediate layer is 0.05 to 30 μm, preferably 0.1 to 30 μm.
20 μm.

In the photoreceptor of the present invention, the charge generating material is not particularly limited as long as it is a material having photosensitivity to the wavelength of the light source. Examples thereof include phthalocyanine pigments, azo pigments, quinacridone pigments, and indigo. Pigments,
Perylene pigments, polycyclic quinone pigments, anthantrone pigments, organic pigment conductive materials such as benzimidazole pigments can be used, and these materials, for example, polyester resin, polyvinyl acetate, polymethacrylate resin,
It is used by being dispersed or dissolved in various binder resins such as polycarbonate resin, polyvinyl butyral resin, and phenoxy resin. In this case, the mixing ratio is 30 to 500 parts by weight with respect to 100 parts by weight of the binder resin, and the film thickness is usually preferably 0.1 to 0.6 μm.

As the charge transport layer, for example, hydrazone-based compounds, enamine-based compounds, styryl-based compounds, amine-based compounds, butadiene-based compounds, and the like can be used. A solution is formed together with a methacrylic acid ester resin, a polystyrene resin, or the like, and applied with a dry film thickness of 10 to 40 μm. If necessary, an antioxidant, an ultraviolet absorber, a leveling agent and the like can be added.

[0018]

EXAMPLES The present invention will be described in detail with reference to examples below, but the present invention is not limited to these examples. Example 1 10 parts by weight of a melamine resin (trade name: Uban 2020, manufactured by Mitsui Toatsu Chemicals, Inc.) as an undercoat layer on an aluminum conductive support having an outer diameter of 30 mm and a length of 255 mm were mixed with 50 parts by weight of methanol. Dissolve in a mixture of 50 parts by weight of methylene chloride, apply the prepared solution by dipping,
Drying was performed at 40 ° C. for 15 minutes to form a 10 μm undercoat layer.

Next, 2 parts by weight of the X-type phthalocyanine and 98 parts by weight of a polyvinyl butyral resin solution dissolved in tetrahydrofuran (THF) are mixed, dispersed by a ball mill for 30 hours, and then dipped on the undercoat layer. It was applied by coating and dried at 100 ° C. for 10 minutes to obtain a charge generation layer.

Next, a hydrazone compound (trade name: CTC)
191, manufactured by Anan Perfume Co., Ltd.) and 10 parts by weight of polycarbonate (trade name: L-1225, manufactured by Teijin Chemicals Limited) 10
Parts by weight were uniformly dissolved in 80 parts by weight of dichloromethane, and this was applied on the charge generation layer by dipping. When applying the charge transport layer, the surface of the charge transport layer was pulled up while being heated by an infrared heater, and the surface temperature of the charge transport layer at this time was observed, and it was confirmed that the temperature was higher than the dew point. Thereafter, the resultant was dried at 100 ° C. for 30 minutes to provide a charge transport layer having a thickness of 20 μm, thereby producing a photoreceptor.

Example 2 A film similar to that of Example 1 was prepared by coating the charge transport layer without heating, and adding 70 parts by weight of dichloromethane in which the charge transport material was dissolved. A photoconductor was prepared in the same manner as in Example 1, except that the thickness was formed.

Example 3 In the same manner as in Example 1 except that the charge transport layer was applied without heating and the dew point was lowered by dehumidifying the coating environment when the charge transport layer was applied. Thus, a photoreceptor was prepared.

Comparative Example A photoconductor was prepared in the same manner as in Example 1, except that the coating was performed without heating with a heater.

After observing the surface of the photoreceptor produced as described above with an optical microscope, the photoreceptor was mounted on a laser beam printer and subjected to a continuous printing test of 50,000 sheets. The results obtained are shown in Table 1 below.

[0025]

[Table 1] * 1: Minimum temperature reached on the surface of the charge transport layer at the time of coating * 2: Dew point of the coating environment when the charge transport layer was coated * 3: Dew condensation when the outermost surface of the charge transport layer was observed at 400 times with an optical microscope The presence of traces of water droplets

As is clear from Table 1 above, Examples 1 to
Photoconductor No. 3 had no black spots and no toner filming on the photoconductor surface, had good image quality, and had no image defects even when used repeatedly.

[0027]

As described above, in the electrophotographic photoreceptor of the present invention, since there is no trace of water droplets due to dew condensation on the outermost surface of the photosensitive layer, toner filming on the drum surface and generation of black spots on the image occur. Could be prevented.

Claims (4)

[Claims] 1. An electrophotographic organic photoreceptor manufactured by forming a photosensitive layer by a dip coating method, wherein the outermost surface of the photosensitive layer has no trace of water droplets due to dew condensation generated during formation of the photosensitive layer. Photoreceptor. 2. The method of manufacturing an electrophotographic photoreceptor according to claim 1, wherein the solid content ratio of the coating solution by the dip coating method is determined by the heat of vaporization at the time of volatilization of the coating solution and the dew point of the coating environment. A method for producing a photoconductor for electrophotography, wherein the ratio is increased to a level that does not result in the following. 3. The method for producing an electrophotographic photosensitive member according to claim 1, wherein the surface temperature of the photosensitive layer at the time of application by the dip coating method is controlled to be equal to or higher than the dew point of the application environment. How to make the body. 4. The method for producing an electrophotographic photoconductor according to claim 1, wherein the photoconductor substrate is heated during application by a dip coating method.