JP3266952B2 - Manufacturing method of cylindrical coated body - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a cylindrical coated body for forming a continuous film having good uniformity of film thickness and no coating defects on the surface of a cylindrical substrate to be coated. More specifically, the present invention relates to a method of manufacturing an electrophotographic photoreceptor for forming a coating film of an organic photoconductor material on a surface of a cylindrical substrate as in the case of manufacturing an electrophotographic photoreceptor drum, for example. Things.

[0002]

2. Description of the Related Art Conventionally, a method of forming a continuous film by spirally coating a surface of a cylindrical substrate is disclosed in JP-B-39-810.
No. 4, JP-A-52-119651,
JP-A-1-231966, JP-A-3-11056
No. 5 and many others are disclosed. However, for example, when a multi-nozzle body as disclosed in JP-A-3-193161 is used for the discharge unit, the pressure inside the nozzle increases due to pressure loss due to the thin nozzle, and the coating liquid is discharged from the nozzle. Due to the release of pressure at the time of discharge, air dissolved in the coating liquid becomes bubbles and often causes coating defects.

[0003] When such coating defects are present on the electrophotographic photosensitive drum, they not only result in defects on the image, but when bubbles are large, the cleaning blade in a machine such as a copying machine or a printer is scratched. It also causes problems such as getting lost. Of course, such a defect is found in the inspection process, and in many cases, it does not occur until a problem occurs when the machine is actually used. However, in this case, there has been a problem that the yield is significantly reduced.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to prevent a coating defect caused by a gas dissolved in a coating liquid, and particularly, to cause a large pressure loss in a coating liquid discharge nozzle. In the case, a method of manufacturing a cylindrical coated body capable of preventing the air dissolved in the coating liquid from becoming bubbles by releasing the pressure when the coating liquid is discharged from the nozzle and preventing the occurrence of coating defects. Is to provide.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem. The gist of the present invention is to rotate a cylindrical substrate around its axis, and to apply a coating liquid from a liquid discharge nozzle. The method of manufacturing a cylindrical coating body, which spirally coats the substrate surface by moving the nozzle relatively in the axial direction of the base while discharging, forms a continuous film. And discharging a coating liquid having a gas solubility of less than the saturated solubility of the gas in the coating liquid under discharge conditions.

Hereinafter, the present invention will be described in detail. There are various methods for discharging a coating solution in which the gas dissolution amount of the coating solution is less than the saturated solubility of the gas in the coating solution under the discharging conditions by the gas reduction treatment in the present invention. Most commonly used methods can be applied, and specifically, there are the following methods.

[0007] A method in which a special synthetic resin film that selectively allows dissolved air to pass therethrough is placed in a vacuum vessel, and a coating solution is passed through the film to degas and then discharge. A method in which the coating liquid is degassed under reduced pressure, and is kept in a state where it does not come in contact with air, and then discharged. A method in which a coating solution is degassed and discharged using ultrasonic cavitation. Utilizing the fact that the higher the temperature of the liquid, the lower the saturated solubility of air, the more the coating liquid is heated and degassed, then cooled and discharged without contact with the gas, or the method of contacting the coating liquid with the gas Method of cooling and discharging in the absence of air.

In these methods, a special synthetic resin film is formed into a thin tube, and when a liquid having a relatively high viscosity such as a coating solution for forming a charge transfer layer of an organic photoconductor film is used, In order to obtain a flow rate corresponding to a large pressure loss and a coating speed, it is necessary to use several units in parallel when using a commercially available device. In order to avoid the reabsorption of degassed air, the methods (1) and (2) need to be equipped with equipment so that the coating solution does not come into contact with air after degassing.

In the method of (1), a stable degassed coating solution can be obtained at a low cost, and when a continuous film is formed by spiral coating on the surface of a cylindrical substrate, a charge transfer layer of an organic photoconductor is preferably used using a multi-nozzle body. This method is very suitable for deaeration of the coating solution used when forming the coating liquid. This method utilizes the difference in solubility of air due to the temperature difference of the coating liquid, and is achieved by discharging a coating liquid having a lower temperature at the time of discharge than the temperature of the coating liquid before coating in a coating liquid tank or the like. The same effect can be obtained even if the liquid supply system is cooled so that the temperature of the coating liquid at the time of discharge is lowered instead of heating the coating liquid tank to degas the coating liquid.

At this time, the larger the difference between the temperature of the coating solution in the coating solution tank and the temperature at the time of discharge, the greater the degassing effect, but it is usually about 10 ° C. or more, preferably about 20 ° C. It is sufficient if there is a temperature difference. However, the liquid temperature of the coating liquid must be lower than the boiling point of the solvent when heating, and higher than the freezing point and lower than the melting point when cooling.

In any case, the effect obtained is small if the liquid feeding system between the coating liquid tank and the coating liquid discharge nozzle is not structured so as not to come into contact with air. As the coating liquid in the present invention, for example, in the case of a coating liquid for an electrophotographic photoreceptor, one or two or more selected from electron transporting materials, photoconductive particles, dye pigments, electron withdrawing compounds and the like. A coating solution obtained by dissolving or dispersing a material and a binder in a solvent is used. The coating liquid is a lubricant, a leveling agent,
A known additive such as an antioxidant may be contained.

Known electron transport materials, photoconductive particles, dyes, electron withdrawing compounds, binders and the like can all be used. As the binder, for example, styrene, vinyl acetate, vinyl chloride, acrylate,
Various polymers such as polymers and copolymers of vinyl compounds such as methacrylic acid esters and butadiene, polyvinyl acetal, polycarbonate, polyester, polysulfone, polyphenylene oxide, polyurethane, cellulose ester, cellulose ether, phenoxy resin, silicon resin and epoxy resin Is mentioned.

As the charge transporting material, for example, 2, 4, 6
-Trinitrofluorenone, tetracyano methane,
Electron-withdrawing substances such as diphenoquinone derivatives, carbazole, indole, imidazole, oxazole, pyrazole, oxadiazole, heterocyclic compounds such as pyrazoline and thiadiazole, aniline derivatives, hydrazone compounds, aromatic amine derivatives, stilbene derivatives, or these And an electron-donating substance such as a polymer having a group consisting of the compound in the main chain or the side chain.

The photoconductive particles that generate charge carriers with extremely high efficiency when absorbing light include, for example, selenium,
Inorganic photoconductive particles such as selenium-tellurium alloy, selenium-arsenic alloy, cadmium sulfide, amorphous silicon; phthalocyanine pigments, perinone pigments, thioindigo, quinacridone, perylene pigments, anthraquinone pigments,
Organic photoconductive particles such as azo pigments, bisazo pigments, trisazo pigments, tetrakisazo pigments, and cyanine pigments are exemplified. Examples of the dye include a triphenylmethane dye, a thiazine dye, a quinone dye, a cyanine dye, a pyrylium salt, a thiapyrylium salt, and a benzopyrylium salt. Examples of the electron withdrawing compound that forms a charge transfer complex with a charge transfer material include quinones, aldehydes, tons, acid anhydrides, cyano compounds,
Electron-withdrawing compounds such as phthalides;

Examples of the solvent for adjusting the coating solution include ethers such as tetrahydrofuran and 1,4-dioxane; ketones such as methyl ethyl ketone and cyclohexanone; aromatic hydrocarbons such as toluene and xylene; N, N-dimethylformamide and acetonitrile Aprotic polar solvents such as, N-methylpyrrolidone, dimethyl sulfoxide;
Esters such as ethyl acetate, methyl formate and methyl cellosolve acetate; and solvents such as chlorinated hydrocarbons such as dichloroethane and chloroform.

As the cylindrical substrate in the present invention, for example, in the case of a cylindrical substrate for an electrophotographic photosensitive member, any of those used in a well-known electrophotographic photosensitive member can be used. Specifically, for example, a metal drum of aluminum, stainless steel, copper, or the like, or a laminate or a vapor-deposit of these metal foils can be used. Further, plastic drums, paper tubes, and the like, which have been subjected to a conductive treatment by applying a conductive substance such as metal powder, carbon black, copper iodide, and a polymer electrolyte together with a suitable binder, may be mentioned. Further, a plastic drum which contains a conductive substance such as metal powder, carbon black, and carbon fiber and is made conductive may be used.

For example, when the coating solution in the present invention is a coating solution for an electrophotographic photosensitive member, the solid content in the coating solution is determined mainly according to the thickness of the layer to be formed. When the charge generation layer is formed, the solid content concentration is preferably 10% by weight or less, more preferably 0.5 to 5% by weight. When a stacked charge transport layer or a single-layer photosensitive layer containing a charge generating material and a charge transport material is formed, a thicker photosensitive layer needs to be formed.
The content is preferably 0% by weight or less, more preferably 10 to 40% by weight.

The layer thickness of the charge generating layer is usually 0.05
The range from μm to 5 μm, preferably from 0.1 μm to 2 μm is suitable. The thickness of the layered charge transport layer is usually 5 μm to 80 μm, preferably 10 μm to 60 μm. The thickness of the single-layer type photosensitive layer is usually 5 μm to 80 μm.
m, preferably 10 μm to 60 μm. In the case of forming a polymer layer or a polymer layer in which conductive fine powder is dispersed, the solid content concentration is preferably 45% by weight or less, more preferably 1 to 35% by weight.

The thickness of the polymer layer or the polymer layer in which the conductive fine powder is dispersed is usually 0.1 μm to 100 μm.
m, preferably 0.2 μm to 80 μm.

[0020]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the following examples unless it exceeds the gist. Example 1 An outer diameter of 80 m was used as a cylindrical substrate to be coated.
m, a thickness of 1 mm, and a length of 340 mm made of an aluminum alloy substrate coated with a charge generation layer by dip coating, and tetrahydrofuran and 1,4-dioxane were mixed in a weight ratio of 65:35 as a coating solution. Solvent

[0021]

Embedded image

A solution prepared by dissolving and dissolving a solid content concentration of 30% by weight was used. The coating solution was heated to about 40 ° C. while slowly stirring with a magnetic stirrer, degassed for about 1 hour, and kept at 40 ° C. after degassing.
As a liquid discharge nozzle, a thin tube with an inner diameter of 0.4 mm is 1.25.
Using a multi-nozzle body arranged in one row at an interval of mm, the number of rotations of the substrate is 276 rpm, the moving speed of the multi-nozzle body is 10.6 mm / s, and the discharge flow rate of the coating liquid is 23.2 ml.
/ Min, and coating was performed in a solvent vapor atmosphere of tetrahydrofuran. At this time, the temperature of the coating liquid was lowered to 25 ° C., which is the room temperature, while passing through the discharge device and the liquid feeding tube, and no bubbles were generated at the time of coating. After this was dried with hot air and evaluated, the electrical characteristics and the image were good.

COMPARATIVE EXAMPLE 1 When the same coating solution as in the example was used without degassing the coating solution, bubbles were generated immediately after the coating solution was discharged from the multi-nozzle body, and the surface of the cylindrical substrate was Dozens of bubbles were formed on the entire coating film of No. 1 and coating defects were found.

[0024]

According to the coating method of the present invention, when a thin film is formed on a substrate, coating defects due to foaming of dissolved air in a coating solution can be prevented. For example, charge transport of an organic photoconductor film to a cylindrical substrate surface can be prevented. Even when a liquid having a relatively high viscosity such as a coating liquid for forming a layer is formed by spiral coating using a discharge part having a large pressure loss such as a multi-nozzle body,
An electrophotographic photosensitive member having no coating defects and no defects on images can be obtained.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B05D 1/00-7/26 G03G 5/05 102

Claims (4)

(57) [Claims] 1. Rotating a cylindrical substrate about its axis,
The coating liquid from the liquid discharge nozzle, by moving the nozzle relatively base body axis direction while discharging, comprising the step of applying to the substrate surface in a spiral shape, to form a continuous film
The manufacturing method of the electrophotographic photosensitive member, the reduction gas processing, an electrophotographic photosensitive that gas dissolved amount of the coating liquid, characterized in that for discharging the saturated solubility than the the coating liquid for the gas with respect to the coating solution discharge conditions How to make the body
Law . 2. The method of manufacturing an electrophotographic photoreceptor according to claim 1, wherein said degassing treatment comprises cooling the coating solution without contact with a gas. 3. The electronic device according to claim 1, wherein the degassing process is performed by heating the coating solution, degassing the coating solution, and then cooling and discharging the coating solution without contacting the gas.
Manufacturing method of photoreceptor . 4. A charge transport layer for an electrophotographic photosensitive member, wherein the coating solution is
Claims: It is a coating liquid for forming
4. The method for producing the electrophotographic photosensitive member according to any one of items 1 to
Law.