JPH05701B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for manufacturing an electrophotographic photoreceptor, and more particularly to a method for coating a charge transport layer of a functionally separated electrophotographic photoreceptor having a charge transport layer and a charge generation layer. Compared to inorganic photoconductive materials, organic photoconductive materials have
Although it has advantages such as non-polluting properties and high productivity, its low sensitivity has made it difficult to put it into practical use. For this reason, several sensitization methods have been proposed, but it is known that an effective method is to use a functionally separated photoreceptor in which a charge generation layer and a charge transport layer are laminated. The charge generation layer is made of azo pigments such as Sudan Red, Diane Blue, and Jenas Green B; quinone pigments such as Algol Yellow, Pyrene Quinone, and Indanthrene Brilliant Violet RRP;
Indigo pigments such as quinocyanine pigments, perylene pigments, indigo and thioindigo, bisbenzimidazole pigments such as India First Orange Toner, phthalocyanine pigments such as copper phthalocyanine, charge generating substances such as quinacridone pigments, polyesters, polystyrenes, fatty acid cellulose esters, It is formed by dispersing it in a binder resin such as polyvinyl acetate, acrylic, polyvinylpyrrolidone, methylcellulose, hydroxypropylmethylcellulose, or polyvinyl butyral and applying it onto a substrate. The charge transport layer provided on the charge generation layer contains a polycyclic aromatic compound such as anthracene, pyrene, phenanthrene, coronene, or indole, carbazole, oxazole, inoxazole, thiazole, imidazole, pyrazole, or oxadiazole in the main chain or side chain. It is formed by dissolving a charge transporting substance such as a compound having a nitrogen-containing cyclic compound such as azole, pyrazoline, thiadiazole, or triazole, or a hydrazone compound in a resin with film-forming properties. This is because the charge transporting substance generally has a low molecular weight and has poor film-forming properties by itself. Examples of such resins include polyester, polysulfone, polycarbonate, polymethacrylic acid esters, polystyrene, and styrene-acrylonitrile copolymer. Among these resins, it is preferable to use styrene or a polymer or copolymer of methyl methacrylate in consideration of electrophotographic properties such as film-forming properties, potential, sensitivity, and photomemory effect. Examples include polystyrene, polymethyl methacrylate, styrene methyl methacrylate copolymer, styrene acrylonitrile copolymer, styrene butadiene copolymer, methyl methacrylate butyl methacrylate copolymer, and the like. Methods for forming the charge transport layer include coating methods such as spraying, roll coater, bar coater, knife coater, blade coater, and dipping. A dip coating method is suitable as a simple coating method that provides a smooth surface. The application process is shown in the attached drawing. The object of the present invention is to set conditions for obtaining the best surface properties in terms of the relationship between the viscosity of the coating liquid and the pull-up coating speed when coating a charge transport layer by a dip coating method. The thickness of the charge transport layer contributes to acceptance potential, sensitivity, etc., and is usually selected in the range of about 10 to 20 μm, but in order to achieve this thickness by dip coating, it is necessary to increase the viscosity and the coating speed. There is a certain relationship. That is, it was found that the larger the values of both viscosity and coating speed, the thicker the film becomes, and where T is the film thickness, N is the viscosity, and S is the coating speed, there is a relationship of T∝NS.
Therefore, in order to obtain a predetermined film thickness, the coating speed may be increased if the viscosity of the coating liquid is low, and the coating speed may be slowed if the viscosity is high. However, as a result of the inventor's experiments, in the case of a coating liquid containing a polymer or copolymer of styrene or methyl methacrylate, if the viscosity is lower than 50 cP (centipoise), the coating speed should not be set to 40 cm/min. If applied under these conditions,
It was found that the vertical unevenness of the coating film thickness was 2μ or more, and the potential unevenness of the photoreceptor was large, making it unsuitable for practical use. Furthermore, since the proportion of solvent was high, dew condensation sometimes occurred due to drying of the solvent from the coating film during pulling. It was also found that when the viscosity is higher than 300 cP, the film thickness becomes too thick no matter how slow the coating speed is, and this is also not suitable for practical use. In the present invention, when dip-coating the charge transport layer, the viscosity N (cP) of the solution is adjusted to 50 to 300 cP, the pulling coating speed S (cm/min) is 40 cm/min or less, and the viscosity N (cP) is adjusted to 50 to 300 cP. ) and pulling application speed S (cm/min)
The solution is applied under conditions such that the relationship S=A/N. Here, A is a constant in the range of 300 to 3000, and it has been found that this depends on the type of resin and charge transport material used, and the desired film thickness. These numerical values will be explained using examples. According to the present invention, the charge transport layer is formed using a polymer containing styrene or methyl methacrylate at a solution viscosity of 50 to 300 cP and a pulling coating speed of 40 cP.
By coating at cm/min or less and in the relationship S=A/N (A=300 to 3000), a charge transport layer with smooth and uniform surface properties and good special properties was successfully formed. Example 1 A cylindrical 80φ x 300mm aluminum cylinder with one end closed as shown in the attached drawings was used as a base. A 4% methanol solution of polyamide resin (trade name: Amilan CM8000, manufactured by Toray Industries) was applied to this by a dipping method at a lifting coating speed of 10 cm/min, and then heated and dried at 80°C for 10 minutes to form a 0.6μ thick undercoat. Added layers. Next, add 10 parts (parts by weight, the same applies hereinafter) of the bisazo pigment with the following structural formula, Polyvinyl butyral resin (product name: ESLETSUKU)
8 parts of BXL (manufactured by Sekisui Chemical Co., Ltd.) and 60 parts of cyclohexanone were dispersed for 20 hours using a sand mill apparatus using 1φ glass beads. 100 parts of methyl ethyl ketone (MEK) was added to this dispersion to prepare a coating liquid. This was applied using the dip coating method at a lifting speed of 10 cm/min, and dried at 80°C for 10 minutes.
A charge generation layer of 0.07μ was formed. next, 7 parts of a hydrazone compound with the structural formula shown, polystyrene resin (product name: Dialex HF-
55 (manufactured by Mitsubishi Monsanto Chemical) was dissolved in monochlorobenzene. Table 1 shows the relationship between parts by weight of monochlorobenzene and solution viscosity.

[Table] These solutions were applied by dipping to a film thickness of 16 μm after drying. Table 2 shows the relationship with the pulling speed.

【table】

[Table] As shown above, good results were obtained at viscosities of 250, 120, and 60 (cP). In addition, the value of A at this time is
It was 1500. A charge transport layer was coated on the charge generation layer under the conditions shown in Table 2, and dried at 100° C. for 1 hour to obtain an electrophotographic photoreceptor. The electrophotographic photoreceptor thus manufactured was heated to -5.6KV.
Corona charging, image exposure, dry toner development, toner transfer to plain paper, urethane rubber blade (hardness
70°, pressure 5gw/cm, angle 20° to photoreceptor)
When I installed it in an electrophotographic copying machine that has a cleaning process such as
In the case of , uneven image density was observed. Example 2 A substrate was coated in the same manner as in Example 1 up to the charge generation layer. Further, 7 parts of the same hydrazone compound as in Example 1 and 10 parts of styrene-methyl methacrylate copolymer resin (trade name: MS200, manufactured by Tetsutsu Kagaku) were dissolved in toluene. Table 3 shows the relationship between the amount of toluene, the viscosity, and the coating speed at which the film thickness was 16 μm.

【table】

[Table] As shown above, good results were obtained at viscosities of 220, 150, and 100 cP, and the value of A was 2400. When copy images were taken using the obtained electrophotographic photoreceptor, images of good quality were obtained with those having a viscosity of 220, 150, and 100 cP, but those with a viscosity of 50 cP had large unevenness.

[Brief explanation of the drawing]

The figure shows an example of equipment for dip coating. The symbols in the diagram are 1...paint film, 2...liquid tank, 3...
...Coating liquid, 4... Cylindrical substrate with one end closed, 5...
Support part, 6... Drive motor (this rotation causes 7
...Turn the lifting screw and pull up the base. ),
8...Vent pipe, 9...Rubber air chamber (8 and 9 take out part of the air trapped inside the base body).

Claims (1)

[Claims] 1. In the step of dip coating a solution containing a polymer or copolymer containing styrene or methyl methacrylate and a charge transporting substance,
Adjust the viscosity N (cP) of the solution to 50 to 300 cP, and set the pulling application speed S (cm/min) to 40 cm/min or less,
Furthermore, the relationship between viscosity N and pulling coating speed S is S=
A method for producing a functionally separated electrophotographic photoreceptor, comprising forming a charge transport layer by applying the solution under conditions such that A/N (A is a constant in the range of 300 to 3000).