JP2853336B2 - Manufacturing method of photoreceptor for electrophotography - 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 an organic function-separated laminated electrophotographic photosensitive member having at least a charge generating layer and a charge transporting layer on a conductive support, and more particularly to a method for producing a charge generating layer. The present invention relates to a method for forming a layer.

[0002]

2. Description of the Related Art An organic pigment such as a phthalocyanine pigment is frequently used as a charge generating substance to be contained in a charge generating layer in an organic function-separated laminated electrophotographic photosensitive member. In this case, the charge generation layer is made of tetrahydrofuran (T) with an organic pigment together with a vinyl chloride resin, a polycarbonate resin, a polyester resin or the like as a binder resin.
It is formed by applying a coating solution dispersed in a solvent such as HF), cyclohexane or dichloroethane on a conductive support by a dipping method or the like.

However, when the charge generation layer is formed by coating as described above, unevenness in film thickness occurs, a ring-shaped stripe pattern,
Poor appearance such as dripping may occur. Many of the causes are related to the viscosity of the coating solution and the evaporation rate of the solvent, and as a countermeasure, other types of resins are mixed with the binder resin of the coating solution or used as a solvent for the coating solution. Low viscosity solvent such as THF (viscosity 0.4
A high viscosity solvent (viscosity of about 2.5 cP to about 3.5 cP) such as butyl carbitol is used as a mixture with the solvent.

[0004]

However, when a solvent in which a high-viscosity solvent is mixed is used for the coating solution for the charge generation layer, the dispersibility of the organic pigment deteriorates, and the organic pigment tends to agglomerate after preparing the coating solution. The problem is that the life of the film becomes short, and the film forming property deteriorates. SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems and to provide an auxiliary method for manufacturing an electrophotographic photoconductor having a charge generation layer with reduced thickness unevenness and poor appearance.

[0005]

According to the present invention, there is provided a method for producing an electrophotographic photoreceptor comprising at least a charge generation layer and a charge transport layer on a conductive support. The generating layer is formed by applying a coating liquid in which a phthalocyanine pigment and a material mainly comprising polyvinyl butyral resin are dispersed in a mixed solvent of a low-viscosity solvent and a high-viscosity solvent, and the weight mixing of the high-viscosity solvent with respect to the low-viscosity solvent is performed. The problem is solved when the ratio is in the range of 10% or more and 30% or less. It is preferable that the weight mixing ratio of the phthalocyanine pigment and the polyvinyl butyral resin in the coating liquid is in the range of 1: 0.5 to 1: 1.5. It is preferable that the low-viscosity solvent is tetrahydrofuran (THF) and the high-viscosity solvent is any one of isophorone, carbitol acetate, and butyl carbitol.

Another object of the present invention is to provide a method for manufacturing an electrophotographic photoreceptor comprising at least a charge generation layer and a charge transport layer on a conductive support, wherein the charge generation layer comprises a phthalocyanine pigment and a polyvinyl butyral resin. It is formed by applying a coating solution in which a material as a main component is dispersed in a mixed solvent of a low-viscosity solvent and a high-viscosity solvent, the low-viscosity solvent is tetrahydrofuran (THF), the high-viscosity solvent is isophorone,
The problem is solved by using one of carbitol acetate and butyl carbitol.

Another object of the present invention is to provide a method of manufacturing an electrophotographic photoreceptor comprising at least a charge generation layer and a charge transport layer on a conductive support, wherein the charge generation layer comprises a phthalocyanine pigment and a polyvinyl butyral resin. It is formed by applying a coating liquid in which a main component material is dispersed in a mixed solvent of a low-viscosity solvent and a high-viscosity solvent. 0.5 to 1: 1.5, wherein the low viscosity solvent is tetrohydrofuran (THF) and the high viscosity solvent is any of isophorone, carbitol acetate and butyl carbitol. You.

[0008]

The polyvinyl butyral resin dissolves well in a wide range of organic solvents, has excellent dispersibility of organic pigments, and has good adhesion to metals and plastics. By making the binder resin of the coating solution of the charge generation layer a material mainly composed of a polyvinyl butyral resin, it is possible to prevent the dispersibility of the organic pigment from being deteriorated by mixing a high-viscosity solvent with the solvent of the coating solution. In addition, a low-viscosity solvent (having a viscosity of 0.4
The weight mixing ratio of the high-viscosity solvent (viscosity of about 2.5 cP to about 3.5 cP) to the cP) is preferably in the range of 10% to 30%. Mixing ratio of high viscosity solvent is 10
If it is less than 30%, the effect of mixing is small. If it exceeds 30%, the effect of the high-viscosity solvent having a high boiling point and a low evaporation rate becomes a problem, which is not preferable. Further, it is preferable that the weight mixing ratio of the phthalocyanine pigment and the polyvinyl butyral resin is in the range of 1: 0.5 to 1: 1.5. If the amount of the phthalocyanine-based pigment is too small, the sensitivity of the obtained electrophotographic photoreceptor will be low, and if it is too large, the film-forming property will be reduced. By using a coating liquid as in the present invention,
Organic pigments are stably and uniformly dispersed and contained over a long period of time, and a coating solution having an appropriate viscosity can be prepared. It can be formed.

[0009]

Embodiments of the present invention will be described below in detail. Example 1 10 parts by weight of metal-free phthalocyanine and polyvinyl butyral resin (Elex B. BM- manufactured by Sekisui Chemical Co., Ltd.)
2) 10 parts by weight of THF using a paint shaker
It was dissolved and dispersed in a mixed solvent of 1,000 parts by weight and 100 parts by weight of carbitol acetate to prepare a coating liquid for a charge generation layer. This coating solution was applied to the outer surface of a cylindrical aluminum support to form a charge generation layer having a thickness of 0.5 μm.
For coating, hold a ring slightly larger than the outer diameter of the cylindrical support so that the ring surface is horizontal, and place the cylindrical support vertically in the ring so that its center axis matches the center axis of the ring. Inserting and supplying a coating liquid between the outer surface of the cylindrical support and the ring to form a coating film on the outer surface of the cylindrical support by moving the two relative to each other in the vertical direction, but of course, the so-called ring coating method was used. It is not limited to this method. On this charge generation layer, 1-phenyl-3- (p-diethylaminostyryl) as a charge transport material
100 parts by weight of 5- (p-diethylaminophenyl) -2-pyrazoline (ASPP) and a polycarbonate resin as a binder resin (C-1 manufactured by Mitsubishi Gas Chemical Co., Ltd.)
400) 100 parts by weight of a coating solution prepared by dissolving 100 parts by weight in 2800 parts by weight of dichloromethane was applied by a dipping method to form a film having a thickness of 18 μm.
m of the charge transport layer was formed to obtain a photoreceptor. Example 2 In Example 1, except that the amount of the polyvinyl butyral resin in the coating solution for the charge generation layer was reduced to half, that is, 5 parts by weight,
A photoconductor was produced in the same manner as in Example 1. Example 3 A photoconductor was prepared by the same way as that of Example 1 except that the amount of polyvinyl butyral resin in the coating solution for the charge generation layer was changed to 15 parts by weight. Each of the coating solutions for the charge generation layer used in the above examples was applied to a viscosity distribution meter (BROOKH
AVEN INSTRUMENTS Corp., BI-90 PARTICLE SIZER)
And the dispersibility was evaluated. The result is shown in FIG.
In FIG. 1, the abscissa indicates the number of days left after the preparation of the coating solution, the ordinate indicates the average particle size of the phthalocyanine pigment, the solid line indicates the value for each coating solution in the examples, and the vertical solid line at the measurement point indicates the variation in the measured values. Show. As can be seen in FIG. 1, the average particle size of the pigment immediately after preparation is 200 nm to 300 nm, but after standing for 7 days is 300 nm to 400 nm. Obviously, this is prevented by the present invention. Therefore, in each of the examples, when the charge generation layer is formed using the coating solution immediately after preparation, a charge generation layer having less unevenness in film thickness and less appearance defects such as liquid dripping is obtained,
Good results were obtained in the evaluation of adhesion by peeling off the adhesive tape. The mixing ratio of the phthalocyanine pigment and the polyvinyl butyral resin in the charge generation layer coating solution is such that the more the phthalocyanine pigment is, the lower the dispersibility, the lower the adhesiveness, the lower the film formability, and the lower the ratio, the lower the photosensitivity as a photoreceptor. Therefore, it was found that a weight mixing ratio in the range of 1: 0.5 to 1: 1.5 was preferable. Also, when the mixing ratio of the high-viscosity solvent to the low-viscosity solvent was examined, the effect of reducing the unevenness of the film thickness and the poor appearance was small when the amount was low, and the evaporation rate of the solvent when viewed as the whole mixed solvent was high when the ratio was high. It was found that the mixing ratio was preferably in the range of 10% by weight or more and 30% by weight or less because the appearance was poor and the appearance defects such as uneven coating increased. In the above embodiments, carbitol acetate was used as the high-viscosity solvent. However, the present invention is not limited to this. For example, butyl carbitol, isophorone, and the like are preferably used. Further, the stacking order of the charge generation layer and the charge transport layer is not limited to the order in the embodiment.

[0010]

According to the present invention, it is possible to form a charge generation layer with less film thickness unevenness and poor appearance, to obtain an excellent electron with less sensitivity unevenness, and to obtain an output image with good image quality and few image defects. A photoreceptor can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing the relationship between the number of days left after preparation of a coating solution and the average particle size of pigments for the coating solution for a charge generation layer of an example.

Claims (5)

(57) [Claims] 1. A method for producing an electrophotographic photoreceptor comprising at least a charge generation layer and a charge transport layer on a conductive support, wherein the charge generation layer comprises a material mainly comprising a phthalocyanine pigment and a polyvinyl butyral resin. Is formed by applying a coating liquid in which is dispersed in a mixed solvent of a low-viscosity solvent and a high-viscosity solvent, and the weight mixing ratio of the high-viscosity solvent to the low-viscosity solvent is 10%.
A method for producing a photoconductor for electrophotography, wherein the content is within the range of 30% or less. 2. The composition according to claim 1, wherein the weight mixing ratio of the phthalocyanine pigment and the polyvinyl butyral resin in the coating solution is in the range of 1: 0.5 to 1: 1.5.
The method for producing the electrophotographic photosensitive member according to the above. 3. The low-viscosity solvent is tetrahydrofuran (TH).
3. The method according to claim 1, wherein F) is selected from the group consisting of isophorone, carbitol acetate and butyl carbitol. 4. A method for producing an electrophotographic photoreceptor comprising at least a charge generation layer and a charge transport layer on a conductive support, wherein the charge generation layer comprises a material mainly comprising a phthalocyanine pigment and a polyvinyl butyral resin. Is formed by applying a coating solution in which is dispersed in a mixed solvent of a low-viscosity solvent and a high-viscosity solvent. The low-viscosity solvent is tetrahydrofuran (THF), and the high-viscosity solvents are isophorone, carbitol acetate and butyl carbyl. A method for producing an electrophotographic photoreceptor according to any of Toll. 5. A method for producing an electrophotographic photoreceptor comprising at least a charge generation layer and a charge transport layer on a conductive support, wherein the charge generation layer comprises a material mainly comprising a phthalocyanine pigment and a polyvinyl butyral resin. Is formed by applying a coating solution in which is dispersed in a mixed solvent of a low-viscosity solvent and a high-viscosity solvent, wherein the weight mixing ratio of the phthalocyanine pigment and the polyvinyl butyral resin in the coating solution is 1: 0.5 to 1: 1.5
Wherein the low viscosity solvent is tetrohydrofuran (THF) and the high viscosity solvent is any of isophorone, carbitol acetate and butyl carbitol.