JPS6377060A - Manufacture of electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To suppress unevenness of image density by heating a support and supplying heat from the support to a coating film in drying it. CONSTITUTION:The reason why the surface of the coating film blushes, that is, becomes opaque and white in drying the coating film is because the temperature of the coating film is lowered below the dew point by the evaporation heat robbed from the coating film necessary for evaporating the solvent and water vapor in the air condenses on its surface. The temperature drop of the coating film can be suppressed with certainty and good reliability by supplying the evaporation heat taken off from the coating film from the heat accumulated by heating the support 3 and controlling the temperature of the support 3. A conductive substrate of an aluminum plate, aluminum drum, or aluminum vapor deposited film, a conductive underlayer 2a formed on the surface of an insulating substrate made of plastics or the like are used for the support, and all the material known as the photosensitive material can be used for the photosensitive film 1, thus permitting the obtained photosensitive body to be restrained from deterioration of photosensitivity and unevenness of printing.

Description

[Detailed Description of the Invention] [Summary] The present invention relates to a method for producing an electrophotographic photoreceptor, and in particular, to a method for producing an electrophotographic photoreceptor, in particular, the amount of heat required to fully heat the support and evaporate at least the coating solvent when producing a photosensitive film by a coating method. The present invention relates to a method for manufacturing an electrophotographic photoreceptor in an electrophotographic system. It is related to.

Electrophotographic systems are widely applied and popular in fields such as laser printers and copying machines. The process involves first uniformly charging the surface of the photoconductor positively or negatively, and then exposing it to light using a laser, LED, etc. to form an electrostatic latent image on the surface of the photoconductor. After developing it into a visible image, it is transferred onto paper, and a printed matter is obtained by melting and fixing it with heat or light.

[Conventional technology]

As electrophotographic photoreceptors for copying machines and laser printers, organic photoreceptors made of organic materials are attracting attention instead of inorganic photoreceptors using selenium or tellurium, which have traditionally been the mainstream. The reason for this is that inorganic photoreceptors are manufactured by vacuum evaporation and are therefore expensive to manufacture, whereas organic photoreceptors can be manufactured by a coating method, resulting in superior productivity @ mass production and lower costs.

The coating methods used to manufacture organic photoreceptors include the dipping method, the doctor blade method, and the wire bar method.

There are spray coating methods, etc., which are appropriately selected depending on the shape of the entire photoreceptor and the support to be coated. For example, in the dipping method, a support is immersed in a coating solution capable of forming a photosensitive M, and then pulled up at a predetermined speed to form a coating film of the coating solution on the support. This is a method of forming a photosensitive film by evaporating and drying (mainly a solvent). With this method, a photosensitive drum using a drum-shaped support can be manufactured seamlessly, and additional coatings can be easily formed, so that a photosensitive film having a multilayer structure can be easily manufactured. Also, according to the blade method, it is difficult to manufacture drum-shaped photoreceptors;
In manufacturing a sheet-like photoreceptor, a long sheet can be manufactured continuously and with a uniform film thickness, and multiple coatings can be applied at the same time.

L Problems to be Solved by the Invention] What is common to all photoresist film production methods using these coating methods is that a coating film of a coating liquid for forming a photoresist film is created, and the volatilization in the coating film is By removing the components, photosensitive MX'! i
-It means to form. Here, what evaporates from the coating film is mainly the volatile solvent that is a component of the coating liquid. The coating solution that forms the coating film comes into contact with the atmosphere over a wide area, but the vapor pressure of the volatile solvent in the atmosphere is generally controlled to be lower than its saturated vapor pressure. The solvent immediately vaporizes and is released from the coating film into the atmosphere, thereby drying and assimilating the coating film and forming a photosensitive film.

However, there was a problem in that when the coating film was dried, the six layers of the film became cloudy and opaque. If cloudiness occurs on the surface in this way, the incident light irradiated to form a layered image will be blocked, resulting in poor apparent sensitivity. In addition, since this clouding occurs unevenly on parts of the surface, there is a problem in that it causes uneven images when printed using a copier or printer. When the solvent evaporates from the membrane, a certain amount of heat is rapidly removed from the membrane as heat of vaporization.
This is because the temperature of the coating film drops to below the dew point, water vapor in the atmosphere condenses on the film surface, and this is incorporated into the film surface during the drying process, creating fine irregularities.

Conventionally, a method to solve this problem is to control the vapor pressure of the solvent in the atmosphere to a high level to slow down the rate of solvent evaporation from the coating film90. By slowing down the speed at which the solvent is taken away, the rapid temperature drop is alleviated and the result 1: prevented. ◇Also, if this method is applied to the immersion method, the solvent evaporation rate is slow and the coating film remains in a liquid state for a long time, so the flow of the coating solution is difficult. [Means for solving the problem] The above problem can be solved by the following manufacturing method. That is, in a method for producing an electrophotographic photoreceptor in which a coating solution T-coating is applied onto a support and dried to form a photoconductive film or at least one organic layer constituting the same, a support ( 3) can be solved by employing a method for producing an electrophotographic photoreceptor characterized by supplying heat from the support to the coating film at least during drying of the coating film.

[Effect]

As mentioned above, the reason why the film surface becomes cloudy and opaque is because the heat of vaporization required for solvent evaporation is taken away from the paint film, which causes the film temperature to drop below the dew point and condensation to form on the surface. I live by putting it away. However, according to the manufacturing method of the present invention, the heat of vaporization taken away from the coating film can be supplied from the support, which has stored heat through heating. temperature drop can be reliably and reliably suppressed.

The support (3) of the present invention includes an aluminum plate, an aluminum drum,
A conductive undercoat layer 2a having conductivity may be applied to the surface of a conductive substrate such as an aluminum vapor-deposited film or an insulating substrate such as plastic.

As the photoresist film 1, any known material can be used.

See Figure 3: Used in the production of so-called single-layer photoreceptors in which photoconductive substances such as polyvinylcarbazole and phthalocyanine are dispersed in a binder resin such as polyester along with a sensitizer such as trinitrofluorenone and chlorinated diazole. be able to.

Refer to FIG. 2. Furthermore, the manufacturing method of the present invention includes the charge generation layer 2c.
The present invention can be applied to the production of at least one layer of a photosensitive film (laminated photoreceptor) composed of a plurality of organic films including a charge transport layer 2d and a charge transport layer 2d. As the charge generation layer 2c, a material in which a charge generation substance such as a phthalocyanine compound or an azo compound is dispersed or dissolved in a binder resin such as polyester, polyvinyl butyral, polyamide, or hydroxypropyl cellulose can be used. Charge transport layer 2d
For example, charge transporting substances such as toracin compounds and pyrazoline compounds are used in polycarbonate, acrylic-styrene,
Examples include those dissolved in a binder resin such as polyester. Note that by the manufacturing method of the present invention, the charge transport layer 2d
In this case, the charge generation layer 2c may be a vapor deposited film of a charge generation substance.

See FIG. 1: Note that an adhesive undercoat layer 2b for improving adhesion and a conductive undercoat layer 2a for imparting conductivity may be provided between the charge generation layer 2d and the photoreceptor substrate 3.
The present invention is also applicable when it is coated by a coating method.

The same applies to the protective layer 20 that may be provided on the surface of the photoresist film for the purpose of preventing mechanical abrasion.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

Example 1. (See Figure 2) A mixture having the above composition was placed in a porcelain pot and dispersed for 40 hours using alumina balls to prepare a '6 charge raw layer coating solution.

Next, place a glass substrate on the hot plate, and fix the aluminum vapor-deposited PET7 (luminium) on top with the aluminum side facing up, and adjust the amount of heat generated by the hot plate so that the surface temperature of the A/side is 30℃. Adjusted 0 On this aluminum vapor deposition surface,
The coating solution was applied using a doctor blade. As a result, clouding of the surface, which often occurs during natural drying, did not occur.The solution was dried at 100° C. for 1 hour to prepare a solution having the above-mentioned charge composition, which was used as a charge transport layer coating solution. #The charge generation layer was heated to about 40° C. in the same manner as before. When the coating solution was applied onto this using a doctor blade, no white spiders that tend to appear on the surface were observed. This was dried at 90° C. for 30 minutes to form a charge transport layer 2d with a film thickness of 18 μm.
Obtained. Note that when applying the coating liquids for the charge generation layer 2c and the charge transport layer 2d, even if the film heated to each temperature is removed from the hot grate together with the glass substrate, the surface will not become cloudy. It didn't happen.

Comparative example 1. A photoreceptor of Comparative Example 1 was obtained in exactly the same manner as in Example 1 except that the film was not heated with a hot plate. Then, upon coating the charge generation layer 2c and the charge transport layer 2d, clouding occurred on the surface.

Regarding these two photoconductors, when the half-decreased exposure amount to helium neon laser light was measured, the photoconductor of Example 1 was 1.8 μJ/ct/l, whereas the photoconductor of Comparative Example 1 was 1.8 μJ/ct/l.
The photoreceptor is 4.5/JJ/C! II, the sensitivity was extremely low.

Example 2 (See Figures 3 and 4) An aluminum drum with an outer diameter of 60mm and a length of 240u was attached to the coating apparatus shown in Figure 4. In the figure, an aluminum drum 4 is connected by a support 8 to an elevator 9 of a dip coater.

A heater 7 is attached to the lower part of the support 8.
The temperature of the aluminum drum 4 was adjusted to about 40° C. by adjusting the power supplied from the heater power source.

The mixture having the above composition was placed in a porcelain pot and dispersed for 40 hours using an alumina ball to prepare a coating solution for a photosensitive film (6t).
The aluminum drum 4 was immersed in the coating solution with a coating amount of 5 and 0, and then pulled up at a rate of 20 cIL/min. No clouding occurred on the surface of the photoresist film 10 shown in FIG. 3 prepared in this manner. This is f! : A single-layer type photoreceptor of Example 2 was obtained by drying at 100° C. for one hour.

Comparative Example 2 When the entire photoreceptor of Comparative Example 2 was prepared in exactly the same manner as in Example 2 except that the drum was not heated, a white spider was observed on the surface.

When these drum-shaped photoreceptors were attached to a laser printer that uses a semiconductor laser as a light source and a printing test was conducted,
The photoconductor of Comparative Example 2 caused uneven printing, whereas the photoconductor of Example 2 had no such unevenness at all.Example 3 (See Figure 2) Aluminum Vapor Deposition Approximately 150 OA of aluminum chloride 7-thalocyanine was vapor-deposited on the aluminum surface of the PET film. This was exposed to gold tetrahydrofuran vapor for 12 hours to form a charge generating layer 2C.

On top of this, a spider-free charge transport layer 2d was coated in the same manner as in Example 1 to obtain a photoreceptor of Example 3. The half-decay exposure of this photoreceptor to 780 nm light was measured and found to be 0.6 μJ/cr/l.

Comparative Example 3 A photoreceptor of Comparative Example 3 was obtained in exactly the same manner as in Example 3, except that heating was not performed on the surface of the charge transport layer. The surface of the charge transport layer of this photoreceptor was white and cloudy.The half-decrease exposure amount of this photoreceptor to 780 um light was 2°0μJ/
It was d.

〔Effect of the invention〕

As described above, according to the manufacturing method of the present invention, it is possible to coat the surface of the photoreceptor 1 and the organic FF 11 constituting it without producing a cloudy sound, thereby reducing the sensitivity of the photoreceptor and printing. Unevenness can be suppressed.

[Brief explanation of the drawing]

FIG. 1 is a general diagram of an electrophotographic photoreceptor that can be manufactured by the manufacturing method of the present invention, and FIG. Cross-sectional views of the photoreceptors of Comparative Examples 1 and 3 degrees, and FIG. 3 are those of Example 2. Comparative Example 2 is a cross-sectional view of the photoreceptor, and the fourth factor is a cross-sectional view of the coating apparatus of the present invention. In the figure, l...Photoresist film, 2...Organic film, 2
a... Conductive subbing layer, 2b... Adhesive subbing layer, 2c... Charge generating layer, 2d...
... Charge transport layer, 2e ... Protective layer, 3...
...Support, 4...Aluminum drum, 5...
- Coating solution amount, 6... Coating liquid, 7... Heater, 8... Support tool, 9... Lifting machine, 0 ordinal 3 Figure Pearl 4 country

Claims (1)

[Claims] In the method of manufacturing an electrophotographic photoreceptor in which a photoconductive film or at least one organic layer constituting the photoconductive film is formed by coating and drying a solution on a support, when drying the coating film, . A method for producing an electrophotographic photoreceptor, comprising supplying heat from the support to the coating film at least during drying of the coating film by heating the support.