JPH06332202A - Production of electrophotographic sensitive body - Google Patents

Abstract

(57) [Summary] [Object] An object of the present invention is to provide a method for producing an electrophotographic photosensitive member capable of stably producing a high-quality electrophotographic photosensitive member free from image defects even during continuous coating for a long period of time. Especially. The present invention is a method for producing an electrophotographic photosensitive member, which comprises a step of applying a coating liquid on a conductive support, wherein the electrophotographic photosensitive member is produced by heating the coating liquid. [Effects] According to the present invention, a gelled product, a crystallized product, an aggregate, etc. do not occur in a coating solution even after continuous coating for a long period of time, so that a high-quality electrophotographic photoreceptor having no image defect can be stably produced. A method of manufacturing an electrophotographic photosensitive member has been made possible.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an electrophotographic photosensitive member, and more particularly to a method for continuously manufacturing an electrophotographic photosensitive member having no image defect.

[0002]

2. Description of the Related Art An electrophotographic photosensitive member is manufactured by forming a photosensitive layer on a support and, if necessary, a conductive layer or an intermediate layer. As a method for producing each of these layers, for example, a selenium photoconductor, a method of directly depositing a substance on the surface of a support by a method such as vacuum deposition, sputtering, and CVD such as an amorphous silicon photoconductor, and a photoconductive substance,
There is a method in which a binder resin or the like is dispersed or dissolved in a solvent to prepare a coating liquid and the substance is attached to the surface of the support by a coating means. The latter is excellent in mass productivity and production cost. In recent years, electrophotographic photoreceptors, especially organic photoreceptors (OPC)
Widely used in the manufacture of.

[0003]

However, this method of manufacturing an electrophotographic photosensitive member has the following problems depending on the composition of the coating liquid.

(1) When the coating solution has a property of gelling with the passage of time, a gelled substance, sol, etc. are generated in the coating solution during long-term continuous coating, which causes coating defects.

(2) When the dissolved substance has a property of crystallizing and is in a supersaturated state, crystals are deposited in the coating liquid with the passage of time, which causes coating defects.

(3) In the case of a coating liquid in which a pigment and a binder resin are dispersed in a solvent, pigment particles form an aggregate with the passage of time in the coating liquid, which causes coating defects.

In particular, when the electrophotographic photoconductor is required to have high sensitivity and high image quality, there are many cases where the photoconductor has a multi-layer structure in which the functions are separated. The following is an example of a four-layer structure.

Conductive layer: A layer coated on a support for the purpose of controlling charge injection properties, preventing diffuse reflection of light, and complementing defects in the support. Intermediate layer: photosensitive layer and support, or conductive layer. A layer that is located in the middle of the layers and functions as a barrier layer against the injection of charges. Charge generation layer: A layer that generates charges upon exposure. Charge transport layer: A layer that transports the charges generated in the charge generation layer. In that case, a low coating defect rate is required for each layer. In selecting materials and solvents, appropriate ones should be selected so that the above problems do not occur, but each layer requires a high level function in order to satisfy the characteristics as an electrophotographic photoreceptor. Therefore, it is unavoidable to use even a material having a problem in coatability, which is a problem in maintaining a good yield rate at all times.

The present invention solves the above problems and provides a method for stably producing a high-quality electrophotographic photosensitive member free from coating defects over a long period of time.

[0010]

That is, the present invention is characterized in that the coating solution is heated in a method for producing an electrophotographic photoreceptor having a step of coating the coating solution on a conductive support. A method for manufacturing an electrophotographic photoreceptor.

The coating liquid used in the present invention is as follows.

The coating liquid used for coating the conductive layer includes, for example, metal powders of aluminum, copper, nickel, silver, etc .; conductive metal oxides such as antimony oxide, indium oxide, tin oxide; polypyrrole, polyaniline, polymer electrolytes. Polymer conductive material such as; carbon fiber, carbon black, graphite powder; or conductive material such as conductive powder whose surface is coated with these conductive materials, and acrylic resin, polyester resin, polyamide resin, polyvinyl acetate Thermoplastic resin such as resin, polycarbonate resin, polyvinyl butyral resin: thermosetting resin such as polyurethane resin, phenol resin, epoxy resin; binder resin such as photocuring resin; alcohol such as methanol, ethanol, butanol, isopropyl alcohol; Methyle Ketone, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone;
Ethers such as diethyl ether, tetrahydrofuran, etc .; Esters such as ethyl acetate, propyl acetate, etc .; Hydrocarbons such as normal hexane, toluene, etc .; those dispersed in other suitable solvents, or additives added as necessary There are things.

Examples of the coating liquid for the intermediate layer include gelatin, ethylene / acrylic acid copolymer, nitrocellulose resin, polyamide resin, polyvinyl alcohol resin,
Polyvinyl alcohol resin and other resins, alcohols such as methanol, ethanol, butanol, and isopropyl alcohol; ketones such as methyl ethyl ketone, acetone, and methyl isobutyl ketone; other substances dissolved in appropriate solvents, or additives as necessary The thing which added. Purified polyamide resins, particularly alcohol-soluble nylon resins such as copolymerized nylon and N-alkoxymethylated nylon, have excellent film-forming properties and electrical properties as an intermediate layer, but easily gel, and the present invention is particularly effective.

The photosensitive layer may have a single layer structure or a laminated structure in which a charge generating layer and a charge transporting layer are functionally separated.

Examples of the coating liquid for the charge generation layer of the laminated structure photoreceptor include azo pigments such as sudan red and chlordian blue; phthalocyanine pigments such as copper phthalocyanine and titanyl phthalocyanine; quinone pigments such as anthanthrone; perylene pigments; indigo. Charge generating substances such as pigments and thermoplastic resins such as acrylic resin, polyester resin, polyamide resin, polyvinyl acetate resin, polycarbonate resin, polyvinyl butyral resin, polyvinyl benzal resin; thermosetting of polyurethane resin, phenol resin, epoxy resin, etc. Binder resin such as resin, alcohol such as methanol, ethanol, butanol, isopropyl alcohol; keto such as methyl ethyl ketone, acetone, methyl isobutyl ketone, cyclohexanone Ethers such as diethyl ether and tetrahydrofuran; Ethyl acetate; Esters such as propyl acetate; Hydrocarbons such as normal hexane and toluene; Other substances dispersed in a suitable solvent, or additives as necessary Examples include those added.

Examples of the coating liquid for the charge transport layer include charge transport substances such as hydrazone compounds, stibene compounds, pyrazoline compounds, oxazole compounds, thiazole compounds and triarylmethane compounds, and acrylic resins, polyester resins, Thermoplastic resin such as polyarylate resin, polyvinyl chloride resin, polycarbonate resin, polyvinyl butyral resin, polymethacrylate resin; binder resin such as polyurethane resin, phenol resin, thermosetting resin such as epoxy resin, methanol, ethanol, butanol , Alcohols such as isopropyl alcohol; ketones such as methyl ethyl ketone, acetone, methyl isobutyl ketone and cyclohexanone; ethers such as diethyl ether and tetrahydrofuran; acetic acid Esters such as chill and propyl acetate; Hydrocarbons such as normal hexane, petroleum ether and toluene; Halogenated hydrocarbons such as monochlorobenzene and dichloromethane; Dispersed in other suitable solvents, or added as necessary The thing which added the agent is mentioned. Further, an example of a coating liquid in which a conductive polymer is dissolved in a solvent is also given. Further, a substance that reduces wear such as Teflon powder may be dispersed.

Furthermore, the manufacturing method of the present invention can be applied not only to the coating of the electroconductive layer, the intermediate layer, the charge generation layer and the charge transport layer of the electrophotographic photoreceptor, but also to the coating of other layers such as an overcoat layer.

The solvent used in the present invention has good solubility with respect to the binder resin in the coating liquid, dispersibility with respect to the pigment, and coating properties, and also boils at a heating temperature of the coating liquid and has a large evaporation amount. It is preferable to select one that is not too much.

In the preparation of the coating liquid for the electrophotographic photosensitive member used in the present invention, simple stirring and mixing may be performed, but if necessary, a dispersing means such as a ball mill, a roll mill or a sand mill is used.

Examples of the heating means used in the present invention include an electric heater and a heat pump. However, when the solvent of the coating liquid is flammable, it is necessary to pay sufficient attention to electric sparks, overheating, etc., and it is preferable to circulate warm water and gently heat it with a heat exchanger.

In the present invention, the location where the coating solution is heated is not particularly limited and may be selected in the coating tank, the coating solution tank, the circulation pipe, or the like.

Regarding the temperature for heating the coating liquid, it is preferable to select a temperature below the boiling point of the solvent that does not impair the characteristics of the coating liquid and is effective in the present invention.

Considering the evaporation and stability of the solvent, 25
The range of 50 ° C to 50 ° C is preferable.

Further, a means for stirring may be provided at an appropriate position such as in the coating tank or the coating liquid tank to make the temperature of the coating liquid uniform.

The present invention is a dip coating method, a spray coating method,
Although it can be applied to a roll coater coating method, a gravure coater coating method, etc., it is particularly effective for a dip coating method in which the residence time of the coating liquid is long.

Further, when the coating liquid is heated, the amount of evaporation of the solvent increases. Therefore, means for preventing evaporation in the coating tank or the like (for example, a lid is provided) or a solvent is automatically dropped to supplement the evaporated solvent. It is effective to provide means.

The principle of the present invention will be described below. Generally, a resin solution has a property of exhibiting crystallinity or forming a gel or sol at a certain temperature or lower, but if the temperature of the solution is increased by heating to increase the Brownian motion, the gelation rate may be decreased, or Gelation can be prevented, and even when the pigment has an aggregating property, the aggregating rate can be reduced or the aggregating can be prevented by heating.

Further, for example, when the charge transporting substance and the resin are dissolved in a solvent, it is necessary to increase the ratio of the charge transporting substance to the resin in order to make the photosensitive member highly sensitive. But,
When the ratio of the charge transporting substance is increased, the charge transporting substance is likely to be precipitated as crystals in the coating liquid, and this degree becomes larger as the temperature of the coating liquid is lower. Therefore, the coating liquid is heated to prevent the precipitation of crystals.

An example of the coating apparatus used in the present invention is shown in FIG.

The coating tank 1 and the coating solution tank 2 are filled with the coating solution. The object to be coated 3 (aluminum cylinder) is immersed in the coating liquid in the coating tank 1 by the object moving device 8 and further pulled up at a constant speed. The coating liquid is constantly supplied from the coating liquid tank 2 to the coating tank 1 by the circulation pump 4. Hot water is supplied from the warm water generator 5 to the heat exchanger 6 to heat the coating liquid. Furthermore, the stirring propeller 7 is used to stir the inside of the coating liquid tank in order to make the temperature uniform and improve the heat exchange efficiency. The replenishing solvent tank 9 replenishes an amount of the solvent corresponding to the solvent evaporated through the flow rate adjusting valve 10.

The electrophotographic photosensitive member manufactured according to the present invention includes a copying machine, a laser printer, an LED printer,
The present invention can be generally applied to electrophotographic devices such as liquid crystal shutter printers, but can also be widely applied to devices such as displays, recording, light printing, plate making, and facsimiles to which electrophotographic technology is applied.

[0032]

EXAMPLES The present invention will be described in more detail with reference to specific examples. (Example 1) High-purity N- obtained by reprecipitation purification of the coating liquid for the intermediate layer
It was prepared by dissolving 1000 parts by weight of methoxymethylated nylon 6 in 4500 parts by weight of methanol and 450 parts by weight of n-butanol. The dissolution was carried out by heating to 40 ° C., and residual non-dissolved material, dust and the like were removed by a filter having an opening diameter of 1 μm. This coating solution was put into the dip coating apparatus of FIG. 1 and adjusted so that the temperature of the coating solution was 37 ° C.

Next, an aluminum cylinder (φ30 mm, 3
60 mm) was prepared, and dip coating was continuously performed for 120 hours with a tact of 2 minutes. Then, the coated aluminum cylinder was dried at 100 ° C. for 20 minutes to form an intermediate layer having a film thickness of 0.7 μm. The obtained coating drum is 100 from the start of coating.
The number of samples was further sampled by 100 every 24 hours, and visual inspection was performed to measure the defective rate due to coating defects.

As a result, as shown in Table 1, in the continuous coating for 120 hours, the defective rate was always low.

Example 2 As a charge generation layer coating liquid, the following structural formula was used.

[0036]

[Chemical 1]

800 parts of disazo pigment, polyvinyl butyral (butyralization ratio 68%, weight average molecular weight 240
00) 400 parts and cyclohexanone 6800 parts
After dispersing for 42 hours with a sand mill using 1 mm glass beads, methyl ethyl ketone (MEK) 12000
Parts were added to prepare a charge generation layer coating solution.

This coating solution was put into the dip coating apparatus shown in FIG. 1 and the coating bath temperature was adjusted to 32 ° C.

Next, an aluminum cylinder (φ30 mm, 360 mm) coated with the intermediate layer of Example 1 was prepared, and dip coating was continuously performed for 120 hours with a 2-minute tact. Then, the coated aluminum cylinder was dried at 80 ° C. for 20 minutes to form a charge generation layer having a thickness of 0.15 μm. 100 coating drums were sampled from the start of coating, and 100 coatings were sampled every 24 hours, and visual inspection was performed to measure the defective rate of coating defects on the charge generation layer.

As a result, as shown in Table 1, in the continuous coating for 120 hours, the defective rate was always low.

Example 3 Next, as a coating liquid for the charge transport layer, the following structural formula was used.

[0042]

[Chemical 2]

4000 parts of the styryl compound and 3000 parts of polycarbonate (weight average molecular weight of 46000) were added to 6000 parts of dichloromethane and 120 parts of monochlorobenzene.
A coating solution for a charge transport layer was prepared by dissolving it in 00 parts of a mixed solvent. Dissolution is performed by heating to 40 ° C, opening diameter 5 μm
The residual non-dissolved material dust and the like were removed by the filter of No. 3. This coating solution was put into the dip coating device shown in FIG.
The temperature was adjusted to 5 ° C.

Next, an aluminum cylinder (φ30 mm, 360 mm) coated with the intermediate layer and the charge generation layer was prepared, and dip coating was continuously performed for 120 hours with a 2-minute tact. Then, apply the coated aluminum cylinder at 120 ℃ 60
After being dried for a minute, a charge transport layer having a film thickness of 20 μm was formed.
100 coatings from the start of coating, and 2 coatings
100 samples were sampled every 4 hours, and visual inspection was performed to measure the defective rate due to coating defects in the charge transport layer.

As a result, as shown in Table 1, the defect rate was always low.

Example 4 As a coating liquid for the conductive layer, the following composition was used: 500 parts by weight of conductive titanium oxide coated with tin oxide (average particle size 0.5 μm) Phenol resin 250 parts by weight Methyl Cellosolve 400 parts by weight Methanol 50 A part by weight was dispersed for 2 hours by a sand mill using glass beads to prepare a coating solution. This coating solution was put into the dip coating apparatus of FIG. 1 and adjusted so that the temperature of the coating solution was 33 ° C.

Next, an aluminum cylinder (φ30 mm, 3
60 mm) was prepared, and dip coating was continuously performed for 120 hours with a tact of 2 minutes. Then, the coated aluminum cylinder was dried at 100 ° C. for 20 minutes to form a conductive layer having a film thickness of 0.7 μm. The obtained coating drum is 100 from the start of coating.
The number of samples was further sampled by 100 every 24 hours, and visual inspection was performed to measure the defective rate due to coating defects.

As a result, as shown in Table 1, the defect rate was always low.

(Comparative Example 1) In Example 1, the hot water generator was turned on.
Except for using FF, the same coating solution adjustment, dip coating, and defect rate measurement as in Example 1 were performed. Liquid temperature of immersion coating liquid is 18 ℃
Met.

As a result, as shown in Table 1, the defective rate increased with time.

(Comparative Example 2) In Example 2, the hot water generator was turned on.
Except for using FF, exactly the same coating preparation, dip coating, and defect rate measurement as in Example 2 were performed. The liquid temperature of the immersion coating liquid was 18 ° C.

As a result, as shown in Table 1, the defective rate increased with time.

(Comparative Example 3) In Example 3, the hot water generator was turned on.
Except for using FF, the same coating material adjustment, dip coating, and defect rate measurement as in Example 3 were performed. The liquid temperature of the immersion coating liquid was 18 ° C.

As a result, as shown in Table 1, the defective rate increased with time.

(Comparative Example 4) In Example 4, the hot water generator was turned on.
Except for using FF, the same paint adjustment, dip coating, and defect rate measurement as in Example 4 were performed. The liquid temperature of the immersion coating liquid was 18 ° C.

As a result, as shown in Table 1, the defective rate increased with time.

In Examples 1 to 4, it can be seen that the failure rate hardly changes even after continuous coating for 120 hours, and the stability of the coating liquid over time is high. However, in Comparative Examples 1 to 4, 120
The defective rate increased with time in continuous coating.

In addition, as a result of observing the coated surface under a microscope after 120 hours of continuous failure in Comparative Example 1 with a microscope, a gelled mass of the resin was observed. In Example 1, no gelled substance was observed, and the defective glass was due to defects on the aluminum base or adhesion of dust.

In Comparative Example 2, after continuous application for 120 hours, the gelled coating solution adhered to the inner walls of the coating tank and the coating tank. Further, the drum having the coating failure was one in which streaky coating unevenness was generated, or an aggregate was attached. In the case of Example 2, the adhesion of the gelled material was very small.

As a result of observing with a microscope the drum in which the coating failure occurred in Comparative Example 3, the crystal of the crystallized charge transport material was found in the charge transport layer.

As a result of observing the drum in which the coating failure occurred in Comparative Example 4 with a microscope, aggregates were found in the conductive layer.

[0062]

[Table 1]

(Example 5) The coating devices used in Examples 1 to 3 were arranged in the order of the intermediate layer, the charge generation layer and the charge transport layer, and a necessary drying device was arranged in the subsequent step of each coating device. Then 3
A continuous automatic coating line for a layer electrophotographic photosensitive member was prepared. The coating conditions for each layer were the same as in Examples 1-3.

The composition after coating was as follows. Coating solution for intermediate layer 6,12,66,610 Copolymer nylon (weight average molecular weight 180,000) 500 parts by weight 6,66,610 Copolymer nylon (weight average molecular weight 140,000) 500 parts by weight Methanol 3000 parts by weight n-butanol 7000 parts by weight The same charge generating layer coating solution as in Example 2 was used.

The following composition was used as the charge generation layer coating liquid.

The following structural formula

[0067]

[Chemical 3]

Hydrazone compound of 5000 parts by weight Polycarbonate (weight average molecular weight of 46000) 3500 parts by weight Monochlorobenzene 14000 parts by weight Dichloromethane 5000 parts by weight Continuous application was carried out for 120 hours using the above continuous automatic application line. From the start of coating, 100 drums were sampled and then every 24 hours, 100 drums were sampled, and these samples were mounted on a copying machine using the Carlson process to perform image evaluation.

As a result, as shown in Table 2, the defective rate was always low in the continuous coating for 120 hours.

(Comparative Example 5) A photosensitive drum was prepared by performing the same continuous coating as in Example 5, but the hot water generator of the intermediate layer coating apparatus was turned off.

Comparative Example 6 A photosensitive drum was prepared by carrying out the same continuous coating as in Example 5, but the hot water generating device of the charge generating layer coating device was turned off.

(Comparative Example 7) A photosensitive drum was prepared by applying the same continuous coating as in Example 5, but the hot water generator of the charge transport layer coating apparatus was turned off.

[0073]

[Table 2]

In Example 5, the defect rate was low and constant even after continuous coating for 120 hours. Most of the defects were due to dust adhesion. However, in Comparative Examples 5 to 7, the defective rate increased with time in continuous coating.

In Comparative Example 5, the number of image defects in which solid white black spots occurred increased with time. The photosensitive drum portion corresponding to the image defect portion had a resin lump on the intermediate layer, and the resin lump generated when the charge generation layer was applied was a coating defect because the charge generation layer coating material was removed. It was a thing.

In the case of Comparative Example 6, streak-shaped image unevenness in the halftone image and image defects of white spots on the black solid image increased with time. In the photosensitive drum portion corresponding to the image defect portion, coating unevenness of the charge generating layer or agglomerates of the charge generating substance were observed.

In the case of Comparative Example 7, black spots and white spot image defects increased with time. Microcrystals of the charge transport material were found in the charge transport layer on the photosensitive drum corresponding to the image defect portion.

[0078]

As is apparent from the above, in the method for producing an electrophotographic photosensitive member of the present invention, by applying the coating solution while heating it, high-quality electrophotography without image defects even in continuous coating for a long period of time. The photoconductor can be stably produced.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing an example of a coating apparatus used in a method for manufacturing an electrophotographic photosensitive member according to the present invention.

[Explanation of symbols]

 1 coating tank 2 coating liquid tank 3 coating object (aluminum cylinder) 4 circulation pump 5 heating water generator 6 heat exchanger 7 stirring propeller 8 coating object moving device 9 replenishing solvent tank 10 flow rate adjusting valve

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Junichi Kishi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (4)

[Claims] 1. A method for manufacturing an electrophotographic photosensitive member, comprising: heating the coating liquid in a method for manufacturing an electrophotographic photosensitive member, including a step of applying a coating liquid on a conductive support. 2. The method for producing an electrophotographic photosensitive member according to claim 1, wherein the coating solution is an intermediate layer coating solution. 3. The method for producing an electrophotographic photosensitive member according to claim 1, wherein the coating liquid is a polyamide resin solution. 4. The method for producing an electrophotographic photosensitive member according to claim 1, wherein the heating temperature of the coating liquid is 25 to 50 ° C.