JP2001222126A - Coating liquid for formation of intermediate layer of electrophotographic photoreceptor and electrophotographic photoreceptor using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating liquid for the formation of an intermediate layer of an electrophotographic photoreceptor which uses a solvent hardly causing problems for human health, which is free from problems of increase in the viscosity with time or gelation, and which does not cause brushing, and to provide an electrophotographic photoreceptor having excellent characteristics for repeated use and environmental characteristics by using that coating liquid. SOLUTION: The coating liquid is to be used for the formation of an intermediate layer of an electrophotographic photoreceptor having an intermediate layer and a photosensitive layer successively formed on a conductive substrate, and the coating liquid contains a mixture solvent of monohydric alcohol of methanol or ethanol and a 1-5C straight chain or branched chain dihydric alcohol, and a binder resin. The electrophotographic photoreceptor is produced by using the coating liquid.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a coating solution for forming an intermediate layer of an electrophotographic photosensitive member and an electrophotographic photosensitive member using the same. More specifically, the present invention relates to a coating solution for forming an intermediate layer of an electrophotographic photoreceptor using a solvent having less health problems, and an electrophotographic photoreceptor using the same and having excellent repetition characteristics and environmental characteristics.

[0002]

2. Description of the Related Art Electrophotographic technology using an electrophotographic photoreceptor (hereinafter, referred to as a "photoreceptor") is one of information recording means utilizing a photoconductive phenomenon of a photoreceptor. And are widely used in fields such as facsimile.

Heretofore, as a photoreceptor, an inorganic photoreceptor having a photosensitive layer mainly composed of an inorganic photoconductive compound such as selenium, zinc oxide, cadmium sulfide and silicon has been widely used. However, these inorganic photoreceptors have not always been satisfactory in terms of sensitivity, thermal stability, moisture resistance and durability. Also, some inorganic photoreceptors contain substances harmful to the human body, and thus have a problem in disposal.

In order to overcome the disadvantages of the inorganic photoreceptor, research and development of an organic photoreceptor having a photosensitive layer containing an organic photoconductive compound as a main component have been actively conducted in recent years. In particular, the function-separated type photoconductor in which the charge generation function and the charge transport function are respectively assigned to different materials has a wide range of material selection, and a photoconductor having any performance can be relatively easily manufactured. A lot of research has been done,
There are many examples that have been put to practical use.

In the preparation of an organic photoreceptor, a conductive substrate is immersed in a coating solution in which a material having a charge generating function and a charge transporting function is dispersed or dissolved, and a charge generating layer and a charge transporting layer are formed on the conductive substrate. A dip coating method for forming is generally used.

[0006] In a photoconductor which is currently put into practical use, since a photosensitive layer is formed directly on a conductive support, carriers are easily injected from the conductive support, and surface charges are microscopically generated. In this case, an image defect is likely to occur, which disappears or decreases to cause an increase in a bright portion potential and a variation in a dark portion potential. Preventing such image defects, and covering defects on the surface of the conductive support,
2. Description of the Related Art An intermediate layer (undercoat layer) is provided between a conductive support and a photosensitive layer for the purpose of improving chargeability, adhesiveness of a photosensitive layer, and coating property.

For example, when an aluminum plate is used as the conductive substrate, an alumite film is formed on the aluminum plate by anodic polarization (alumite processing). Although the characteristics of the photoreceptor are improved by the alumite film, this method has a problem in cost because equipment for alumite processing is required.

Generally, the intermediate layer is formed by a method of dipping and pulling up a conductive substrate in a coating solution in which a resin as a binder and a metal oxide are dissolved or dispersed in an appropriate solvent, that is, a dip coating method. In general, water-soluble nylon is often used as a binder resin, titanium oxide is used as a metal oxide, and an alcohol-based solvent is often used as a solvent (see, for example, Japanese Patent Application Laid-Open No. 7-234531).

However, when a coating solution containing an alcohol-based solvent is repeatedly used, problems such as an increase in viscosity of the coating solution with time and gelation occur. Such a problem,
This is a major obstacle in forming an intermediate layer having a uniform thickness over a long period of time. In particular, when the most common alcohol-based solvent is methanol, a clouding phenomenon called brushing occurs when the solvent evaporates from the coating film. This phenomenon occurs because moisture in the air condenses on the surface of the coating film due to heat absorption when methanol evaporates, and is an undesirable phenomenon that deteriorates the film characteristics of the formed intermediate layer.

[0010] Such brushing phenomenon can be prevented by slowing down the evaporation rate of the solvent. For example, a method of adding a high-boiling solvent to a low-boiling solvent or a method of replacing the solvent with a high-boiling solvent can be used. Specifically, there is a method using a mixed solvent of methanol and dichloroethane.However, since dichloroethane is a chlorinated solvent and has ozone hole destruction, environmental pollution, health problems, etc., there is no alternative solvent. It has been demanded.

[0011]

DISCLOSURE OF THE INVENTION The present invention relates to a method for forming an intermediate layer of a photoreceptor using a solvent having little health problem, free from problems such as viscosity increase and gelation over time and free from brushing. It is an object of the present invention to provide a coating solution of (1), and a photoreceptor using the same and having excellent repetition characteristics and environmental characteristics.

[0012]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, as a solvent for a coating solution for forming an intermediate layer of a photoreceptor, a solvent having a low health problem has been specified. By using a mixed solvent consisting of a monohydric alcohol and a dihydric alcohol, there is no problem such as viscosity increase or gelation over time, and brushing does not occur, and the photoreceptor using the same has repetitive characteristics and They have found that they have excellent environmental characteristics, and have completed the present invention.

Thus, according to the present invention, there is provided a coating solution for forming an intermediate layer of a photosensitive member in which an intermediate layer and a photosensitive layer are sequentially formed on a conductive substrate, wherein the coating solution is a monohydric alcohol of methanol or ethanol. And a linear or branched dihydric alcohol having 1 to 5 carbon atoms, and a coating solution for forming an intermediate layer of a photoreceptor, characterized by containing a binder resin. .

Further, according to the present invention, there is provided a photoconductor in which an intermediate layer and a photosensitive layer are sequentially formed on a conductive substrate, wherein the intermediate layer is formed using the above-mentioned coating solution. A photoreceptor is provided.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The solvent used for the coating solution for forming the intermediate layer of the photoreceptor of the present invention (hereinafter referred to as "coating solution for intermediate layer") is a monohydric alcohol of methanol or ethanol, It is a mixed solvent comprising 1 to 5 linear or branched dihydric alcohols.

Of the monohydric alcohols of methanol and ethanol, methanol is particularly preferred. Methanol is excellent in coating properties and drying properties, and is a preferable solvent for the environment. However, methanol alone causes a problem of brushing when evaporating from a coating film. The brushing problem is solved by adding a specific dihydric alcohol to methanol. Methanol is preferred because it not only increases the drying rate of the coating solution for the intermediate layer and increases the productivity of the intermediate layer, but also imparts excellent storage stability to the coating solution for the intermediate layer. On the other hand, a monohydric alcohol having a relatively high boiling point, such as isopropyl alcohol, is not preferable because the drying speed becomes higher and the coating liquid sags as compared with the case where methanol or ethanol is used.

Examples of the linear or branched dihydric alcohol having 1 to 5 carbon atoms include methylene glycol, ethylene glycol, propylene glycol, trimethylene glycol, butanediol, methylpropylene glycol and pentanediol. And
Of these, methylpropylene glycol is particularly preferred.

Among the above-mentioned dihydric alcohols, those having a high molecular weight are not preferable in terms of coating properties and drying properties, since the boiling point increases when a mixed solvent is used. The boiling point of methylpropylene glycol is 118 to 119 ° C., which is slightly higher than the boiling point of methanol. If the mixed solvent is a combination of methanol and methylpropylene glycol, the drying speed of the coating solution is higher than that of methanol alone. Can be slightly delayed, and aggregation of moisture in the air due to heat absorption when the solvent evaporates can be prevented, and as a result, brushing can be prevented. Further, excellent storage stability can be imparted to the coating solution for the intermediate layer.

It is preferable that the monohydric alcohol is contained more than the dihydric alcohol by weight. A more preferred weight ratio between the monohydric alcohol and the dihydric alcohol is 98/2 to
70/30.

When the weight ratio of the monohydric alcohol to the dihydric alcohol is in the range of 98/2 to 70/30, not only brushing does not occur, but also the drying speed of the coating liquid is moderately high, and the mass productivity of the intermediate layer is increased. And unevenness in film thickness during dip coating can be prevented. If the monohydric alcohol exceeds the above range, brushing tends to occur in drying the coating solution, which is not preferable. On the other hand, if the dihydric alcohol exceeds the above range, the drying speed of the coating solution is slowed, and the coating film tends to become non-uniform due to dripping and the drying time is prolonged, which is not preferable.

As the binder resin used in the coating solution for the intermediate layer of the present invention, a synthetic resin generally used in this field can be used, but water-soluble nylon is particularly preferred. By using water-soluble nylon as the binder resin, a coating liquid for an intermediate layer having excellent storage stability can be obtained.

The coating liquid for an intermediate layer of the present invention may further contain a metal oxide in order to adjust the electric resistance of the intermediate layer. By containing a metal oxide, a photoreceptor having excellent repetition characteristics and environmental characteristics can be obtained.

Examples of the metal oxide include titanium oxide, zinc oxide, tin oxide and indium oxide, among which titanium oxide is preferred. By using titanium oxide as the metal oxide, a photoconductor having excellent repetition characteristics can be obtained.

By using the above-mentioned mixed solvent of monohydric alcohol and dihydric alcohol as the solvent of the coating solution for the intermediate layer of the present invention, it is possible to prevent the viscosity of the coating solution from increasing over time and gelation. Although these mechanisms are unknown, it is presumed that the dihydric alcohol acts in a direction to stabilize the zeta potential of the metal oxide particles.

Titanium oxide includes rutile type and anatase type, but rutile type is preferred in view of dispersibility and coating properties. By using rutile type titanium oxide, a coating solution for an intermediate layer having excellent storage stability can be obtained.

The surface of titanium oxide may be coated with a metal oxide such as aluminum oxide or zirconium oxide in order to adjust the electric resistance of the intermediate layer.

It is preferable that the titanium oxide is contained in a larger proportion by weight than the binder resin (eg, water-soluble nylon). A more preferable weight ratio of the binder resin to the titanium oxide is 2/98 to 50/50.

When the titanium oxide is contained more than the binder resin, a coating solution for an intermediate layer having excellent storage stability can be obtained, and a photoreceptor having excellent repetition characteristics can be obtained. If the binder resin exceeds the above-mentioned range, the viscosity of the coating solution is increased, and the coating properties and the repetition properties are liable to decrease. On the other hand, when the content of titanium oxide exceeds the above range, the repetition characteristics and the dispersibility are likely to decrease due to the decrease in the electric resistance of the intermediate layer.

The weight ratio of the mixed solvent in the coating solution for the intermediate layer of the present invention is preferably 85 to 95%. If the amount of the mixed solvent exceeds 95%, the solid content in the coating solution is reduced, and the wet film thickness for obtaining the intermediate layer having a predetermined film thickness is not preferable. Therefore, it is not preferable to use a solvent having a low boiling point in consideration of productivity, because the drying (evaporation) rate is increased and brushing is easily caused. On the other hand, if the solid content exceeds 15%, the viscosity of the coating solution increases, and the long-term storage stability of the coating solution decreases, which is not preferable.

The coating solution for the intermediate layer of the present invention comprises a solvent mixture of the above-mentioned monohydric alcohol and dihydric alcohol, a binder resin, and a metal oxide optionally added to a paint shaker, a ball mill, a sand mill, an attritor. It is obtained by mixing by a known method using a vibration mill or an ultrasonic disperser, and uniformly dispersing the metal oxide.

The photoreceptor of the present invention is obtained by forming an intermediate layer on a conductive substrate using the coating liquid for an intermediate layer obtained as described above, and then forming a photosensitive layer on the intermediate layer. can get.

As a method for forming the intermediate layer, a method generally used in this field can be applied, but a dip coating method is particularly preferable. FIG. 1 is a schematic diagram of a dip coating apparatus 1 that can be used for forming an intermediate layer. The apparatus includes an elevating / lowering device for moving the photosensitive layer 3 including the conductive substrate 2, the elevating ball screw 5, the conductive substrate holding unit 6, the coating speed control device 7, and the motor 8 in the vertical direction;
And a circulating coating tank for accommodating the coating liquid 9 while stirring it, comprising the coating tank 10, the overflow tank 11, the circulation path 12, the stirring tank 13, the circulation path 14, the liquid feed pump 15 and the stirrer 17. . Arrow 16 indicates the direction of circulation of the coating liquid.

As the conductive substrate, those commonly used in this field are used, for example, aluminum, aluminum alloys (eg, aluminum tin oxide and indium oxide), metal drums such as copper, zinc, stainless steel and titanium. And a metal plate (sheet), a polymer material such as polyethylene terephthalate, nylon, and polystyrene; a drum, a sheet, and a seamless belt obtained by performing metal foil lamination or metal vapor deposition on hard paper.

The preferred thickness of the intermediate layer for achieving the performance required of the intermediate layer is in the range of 0.01 to 10 μm, particularly preferably 0.5 to 5 μm. When the thickness of the intermediate layer is less than 0.01 μm, the intermediate layer substantially does not function as an intermediate layer, and cannot cover the defects of the conductive substrate to obtain uniform surface properties. Cannot be prevented, and the chargeability is undesirably reduced. When the thickness of the intermediate layer exceeds 10 μm,
It is not preferable because not only the film formation becomes difficult but also the mechanical strength decreases. Further, the electric resistance of the intermediate layer is increased, the transport of carriers generated during light irradiation is prevented, the residual potential is increased, and the sensitivity of the photoreceptor is undesirably reduced.

The photoreceptor thus formed using the coating solution for an intermediate layer of the present invention has very excellent image characteristics due to its excellent coating properties and stability of the coating solution, and has excellent repetition. With characteristics and environmental characteristics.

The structure of the photosensitive layer in the photosensitive member of the present invention is as follows.
It is a function-separated type consisting of two layers, a charge generation layer and a charge transport layer. Hereinafter, the case where the charge generation layer and the charge transport layer are sequentially formed on the intermediate layer will be described, but the order of forming these two layers is not particularly limited.

The charge generation layer can be formed by a known method using a material usually used in this field. Specifically, a charge generation layer (CGM) is dispersed in a binder resin or a solvent as required, and a charge generation layer coating solution prepared by coating (for example, dip coating) on the intermediate layer is used for charge generation. Form a layer.

Examples of CGM include phthalocyanine compounds (pigments) of metal or metal, bisazo compounds (pigments) such as chlorodiane blue, azo compounds (pigments) such as trisazo compounds, squarium compounds, azurenium compounds, perylene System compounds, indigo compounds, quinacridone compounds, polycyclic quinone compounds, cyanine dyes, xanthene dyes, and charge transfer complexes composed of poly-N-vinylcarbazole and trinitrofluorene, and the like. Two or more kinds may be used as a mixture.

As the binder resin, polystyrene resin, polyethylene resin, polypropylene resin, polyacryl resin, polymethacryl resin, polybutyral resin,
Polyvinyl chloride resin, polyvinyl acetate resin, polyvinyl butyral resin, polyepoxy resin, polyurethane resin, polyphenol resin, polyester resin, polyalkyd resin, polycarbonate resin, polysilicon resin and polymelamine resin, and repeating units of these resins Copolymer resins containing two or more types are exemplified.

Examples of the solvent include halogenated hydrocarbons such as methylene chloride and dichloroethane; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; esters such as ethyl acetate and butyl acetate; ethers such as tetrahydrofuran and dioxane; Examples include aromatic hydrocarbons such as benzene, toluene and xylene, aprotic polar solvents such as N, N-dimethylformamide and N, N-dimethylacetamide, and mixed solvents thereof.

The coating solution for the charge generating layer is prepared by mixing the above-mentioned CGM, binder resin and solvent by a known method using a paint shaker, a ball mill, a sand mill, an attritor, a vibration mill or an ultrasonic disperser.
It is obtained by uniformly dispersing M and the binder resin.

As a method for applying the coating solution for the charge generation layer,
Examples include a spray method, a bar coating method, a roll coating method, a blade method, a ring method, and a dip coating method. A dip coating method is preferable in terms of productivity and cost.

The charge transport layer can be formed by a known method using a material usually used in this field. Specifically, a charge transport layer coating solution prepared by dissolving a charge transport material (CTM) in a solvent together with a binder resin as necessary is applied onto the charge generation layer (for example, dip coating).
Thus, a charge transport layer is formed.

Examples of CTM include carbazole derivatives, oxazole derivatives, oxadiazole derivatives,
Thiazole derivatives, thiadiazole derivatives, triazole derivatives, imidazole derivatives, imidazolone derivatives,
Imidazolidine derivative, bis imidazolidine derivative, hydrazone compound, styryl compound, benzidine derivative,
Examples thereof include poly-N-vinyl carbazole, poly-1-vinyl bilen, and poly-9-vinyl anthracene. These CTMs may be used as a mixture of two or more as necessary.

The binder resin is not particularly limited as long as it is a resin compatible with CTM. Polycarbonate resin, polyvinyl butyral resin, polyamide resin,
Examples include polyester resin, polyketone resin, polyepoxy resin, polyurethane resin, polyvinyl ketone resin, polystyrene resin, polyacrylamide resin, polyphenol resin, and polyphenoxy resin.

The coating solution for the charge transport layer is prepared by using a solvent (for example, tetrahydrofuran) exemplified in the above-mentioned CTM, binder resin, and coating solution for the charge generation layer, in a paint shaker, ball mill, sand mill, attritor, vibration mill or the like. It is obtained by mixing by a known method using an ultrasonic disperser or the like to form a uniform solution. Further, a known plasticizer, sensitizer, and silicone-based leveling agent may be added to the charge transport layer coating liquid.

The charge transport layer can be formed in the same manner as the intermediate layer and the charge generation layer.

To reduce the fatigue deterioration of the photoreceptor when repeatedly used or to improve the durability of the photoreceptor, a known antioxidant, an electron-accepting substance, a surface modification An appropriate amount of an agent, a plasticizer and an environment-dependent reducing agent may be added.

In order to improve the durability of the photosensitive member, a non-photosensitive layer such as a protective layer may be provided in addition to the photosensitive layer, if necessary. The protective layer can be formed using a thermoplastic resin, a photocurable resin, or a thermosetting resin, and includes inorganic materials such as ultraviolet inhibitors, antioxidants, and metal oxides, organometallic compounds, and electron-accepting materials. Etc. may be included.

The photosensitive layer and the protective layer may be mixed with a plasticizer such as a dibasic acid ester, a fatty acid ester, a phosphoric acid ester, a phthalic acid ester, and a chlorinated paraffin, if necessary, to improve processability and flexibility. The mechanical properties may be improved so as to impart properties, and a leveling agent such as a silicone resin may be added.

The photoreceptor of the present invention can be used as an image forming apparatus by a reversal development process, for example, an electrophotographic copying machine, a laser,
It can be used in various printers using an LED as a light source, an electrophotographic plate making system, and the like.

[0052]

EXAMPLES The present invention will be described specifically with reference to Examples and Comparative Examples, but the present invention is not limited by these Examples.

Example 1 Methyl alcohol 80.75
Parts by weight of a mixed solvent of 4.25 parts by weight of methyl propylene glycol and rutile type titanium oxide (manufactured by Ishihara Sangyo, TT
A mixture of 10 parts by weight of OM-1) and 5 parts by weight of a water-soluble copolymerized nylon resin (CM8000, manufactured by Toray Co., Ltd.) as a binder resin was subjected to a dispersion treatment for 8 hours using a paint shaker, and a coating solution for an intermediate layer was prepared. I got Table 1 shows the conditions for preparing the coating solution for the intermediate layer.

[0054]

[Table 1]

Using the dip coating apparatus shown in FIG. 1, the prepared intermediate layer coating liquid 9 is dip-coated on the conductive substrate 3.
An intermediate layer having a dry film thickness of about 1.3 μm was formed.

When the film thickness of the formed intermediate layer in the longitudinal direction (the pulling direction at the time of dip coating) was measured, it was found that the intermediate layer was coated uniformly. FIG. 2 shows the relationship (film thickness profile) between the distance from the upper end of the conductive substrate and the thickness of the intermediate layer. The storage stability of the coating solution for an intermediate layer obtained in Example 1 was good.

Next, a charge generating layer and a charge transporting layer were sequentially formed on the intermediate layer to obtain a laminated photoreceptor. Specifically, 1.5 parts by weight of a bisazo pigment (chlorodiane blue) having the chemical structure shown below, 1.5 parts by weight of a polybutyral resin (XYGS, manufactured by Union Carbide), and 97 parts by weight of methyl isobutyl ketone were mixed. The resultant was subjected to a dispersion treatment using a paint shaker for 10 hours to obtain a coating liquid for a charge generation layer. The conductive substrate on which the intermediate layer was formed was immersed in the coating liquid for a charge generation layer using the dip coating apparatus shown in FIG. 1 to form a 0.3 μm dry charge generation layer on the intermediate layer.

[0058]

Embedded image

Further, 1 part by weight of a hydrazone-based charge transporting material (ABPH, manufactured by Nippon Kayaku), 1 part by weight of a polycarbonate resin (Panlite L-1250, manufactured by Teijin Chemicals) and a silicone leveling agent (KF, manufactured by Shin-Etsu Chemical Co., Ltd.)
-96) 0.00013 parts by weight was added to 15 parts by weight of tetrahydrofuran, heated to 45 ° C, stirred and mixed,
After complete dissolution, the mixture was naturally cooled to obtain a coating solution for a charge transport layer. Similarly to the charge generation layer, the conductive substrate on which the intermediate layer and the charge generation layer were sequentially formed was immersed in the charge transport layer coating solution to form a charge transport layer having a dry film thickness of 20 μm on the charge generation layer.

The photoreceptor produced as described above was mounted on a copying machine (manufactured by Sharp, SF-2030), and image inspection and confirmation of electrical characteristics were carried out. Did not. The results obtained are shown in Table 2 together with the storage stability of the coating solution (storage stability of the coating solution).

[0061]

[Table 2]

Example 2 As a coating solution for the charge generation layer,
A mixture of 1 part by weight of a phthalocyanine pigment, 1 part by weight of a polybutyral resin (manufactured by Sekisui Chemical, Eslec BM-2) and 120 parts by weight of cyclohexanone was subjected to a dispersion treatment for 12 hours using a paint shaker, and the coating liquid for a charge generating layer was applied. I got

Except for forming a charge generation layer using the obtained coating solution for a charge generation layer, a laminated photoreceptor was prepared in the same manner as in Example 1, and image inspection and confirmation of electrical characteristics were performed. As a result, there was no problem in both the image and the electrical characteristics. Further, when the produced photoreceptor was mounted on a digital copying machine (AR-330, manufactured by Sharp) and image inspection and electric characteristics were confirmed, there was no problem in both image and electric characteristics. The results obtained are shown in Table 2 together with the storage stability of the coating solution.

Example 3 As a coating solution for the intermediate layer, a mixed solvent of ethyl alcohol 80.75 parts by weight and methylpropylene glycol 4.25 parts by weight was mixed with rutile type titanium oxide (TTOM-1 manufactured by Ishihara Sangyo). A mixture of 10 parts by weight and 5 parts by weight of a water-soluble copolymer nylon resin (CM8000, manufactured by Toray Co., Ltd.) as a binder resin was subjected to a dispersion treatment for 8 hours using a paint shaker to obtain a coating liquid for an intermediate layer. Table 1 shows the conditions for preparing the coating solution for the intermediate layer.

A laminated type photoreceptor was prepared in the same manner as in Example 1 except that an intermediate layer was formed using the obtained coating solution for an intermediate layer, and image inspection and electrical characteristics were confirmed. However, there was no problem in both the image and the electrical characteristics.

When the film thickness of the formed intermediate layer in the longitudinal direction (the pulling direction at the time of dip coating) was measured, it was found that the intermediate layer was uniformly coated. The storage stability of the coating solution for an intermediate layer obtained in Example 3 was good.
The results obtained are shown in Table 2 together with the storage stability of the coating solution.

Example 4 As a coating solution for an intermediate layer, a mixed solvent of methyl alcohol (59.5 parts by weight) and methyl propylene glycol (25.5 parts by weight) was mixed with rutile-type titanium oxide (TTOM-1 manufactured by Ishihara Sangyo). 10 parts by weight and a water-soluble copolymerized nylon resin as a binder resin (manufactured by Toray,
A mixture of 5 parts by weight of CM8000) was dispersed for 8 hours using a paint shaker to obtain a coating solution for an intermediate layer. Table 1 shows the conditions for preparing the coating solution for the intermediate layer.

Except for forming an intermediate layer using the obtained coating solution for an intermediate layer, a laminated photoreceptor was prepared in the same manner as in Example 1, and image inspection and confirmation of electrical characteristics were performed. However, there was no problem in both the image and the electrical characteristics.

When the film thickness of the formed intermediate layer in the longitudinal direction (the pulling direction at the time of dip coating) was measured, it was found that the intermediate layer was uniformly coated. The storage stability of the coating solution for an intermediate layer obtained in Example 4 was good.
The results obtained are shown in Table 2 together with the storage stability of the coating solution.

Example 5 As a coating solution for an intermediate layer, a mixed solvent of methyl alcohol 80.75 parts by weight and methyl propylene glycol 4.25 parts by weight was mixed with a water-soluble copolymer nylon resin as a binder resin (manufactured by Toray Industries, Ltd.). , CM80
00) A mixture of 15 parts by weight was subjected to a dispersion treatment for 8 hours using a paint shaker to obtain a coating solution for an intermediate layer.
Table 1 shows the conditions for preparing the coating solution for the intermediate layer. The coating liquid for the intermediate layer had low storage stability and showed an increase in viscosity two days after preparation.

A laminated photoreceptor was prepared in the same manner as in Example 1 except that an intermediate layer was formed using the obtained coating solution for an intermediate layer, and image inspection and electrical characteristics were confirmed. However, a remarkable increase in the electrical characteristics, especially the residual potential, upon repeated use was observed. The results obtained are shown in Table 2 together with the storage stability of the coating solution.

Example 6 As a coating solution for an intermediate layer, a mixed solvent of 34 parts by weight of methyl alcohol and 51 parts by weight of methylpropylene glycol was mixed with 10 parts by weight of rutile-type titanium oxide (TTOM-1 manufactured by Ishihara Sangyo Sangyo). Water-soluble copolymer nylon resin as a binder resin (CM80, manufactured by Toray)
00) A mixture of 5 parts by weight was subjected to a dispersion treatment for 8 hours using a paint shaker to obtain a coating solution for an intermediate layer. Table 1 shows the conditions for preparing the coating solution for the intermediate layer.

A laminated photoreceptor was prepared in the same manner as in Example 1 except that an intermediate layer was formed using the obtained coating solution for an intermediate layer, and image inspection and electrical characteristics were confirmed. . The results obtained are shown in Table 2 together with the storage stability of the coating solution. After the formation of the intermediate layer, the film thickness was measured in the longitudinal direction (the pulling direction at the time of dip coating), and it was found that there was film thickness unevenness (dripping). FIG. 2 shows the film thickness profile. In Example 6, the dispersibility of titanium oxide in the coating solution for the intermediate layer was low, and a uniform coating film could not be obtained.

Example 7 As a coating solution for the intermediate layer, a mixed solvent of 84.15 parts by weight of methyl alcohol and 0.85 parts by weight of methylpropylene glycol was mixed with rutile-type titanium oxide (TTOM-1 manufactured by Ishihara Sangyo). A mixture of 10 parts by weight and 5 parts by weight of a water-soluble copolymer nylon resin (CM8000, manufactured by Toray Co., Ltd.) as a binder resin was subjected to a dispersion treatment for 8 hours using a paint shaker to obtain a coating liquid for an intermediate layer. Table 1 shows the conditions for preparing the coating solution for the intermediate layer.

A laminated type photoreceptor was prepared in the same manner as in Example 1 except that an intermediate layer was formed using the obtained coating solution for an intermediate layer, and image inspection and electrical characteristics were confirmed. . The results obtained are shown in Table 2 together with the storage stability of the coating solution. Vertical streaks due to brushing of the intermediate layer appeared on the image as image defects.

Example 8 As a coating solution for the intermediate layer, 10 parts by weight of rutile type titanium oxide (TTOM-1 manufactured by Ishihara Sangyo) was mixed with a mixed solvent of 51 parts by weight of methyl alcohol and 34 parts by weight of methyl propylene glycol. Water-soluble copolymer nylon resin as a binder resin (CM80, manufactured by Toray)
00) A mixture of 5 parts by weight was subjected to a dispersion treatment for 8 hours using a paint shaker to obtain a coating solution for an intermediate layer. Table 1 shows the conditions for preparing the coating solution for the intermediate layer.

Except that an intermediate layer was formed using the obtained coating solution for an intermediate layer, a laminated photoreceptor was manufactured in the same manner as in Example 1, and image inspection and electrical characteristics were confirmed. . The results obtained are shown in Table 2 together with the storage stability of the coating solution. After the formation of the intermediate layer, the film thickness was measured in the longitudinal direction (the pulling direction at the time of dip coating), and it was found that there was film thickness unevenness (dripping). FIG. 2 shows the film thickness profile.

Comparative Example 1 Water 8 was used as the coating solution for the intermediate layer.
0.75 parts by weight and methyl propylene glycol 4.25
10 parts by weight of rutile type titanium oxide (manufactured by Ishihara Sangyo, TTOM-1) and a water-soluble copolymer nylon resin (manufactured by Toray, CM800) as a binder resin
0) The mixture containing 5 parts by weight was subjected to a dispersion treatment for 8 hours using a paint shaker to obtain a coating liquid for an intermediate layer. Table 1
Shows the preparation conditions of the coating solution for the intermediate layer.

Except that an intermediate layer was formed using the obtained coating solution for an intermediate layer, a laminated type photoreceptor was produced in the same manner as in Example 1, and image inspection and confirmation of electrical characteristics were performed. . The results obtained are shown in Table 2 together with the storage stability of the coating solution. Due to the poor solubility of the binder resin, the viscosity of the coating liquid increased significantly in one week. After the formation of the intermediate layer, the film thickness was measured in the longitudinal direction (the pulling direction at the time of dip coating), and it was found that there was film thickness unevenness (dripping). FIG. 2 shows the film thickness profile.

Example 9 As a coating solution for the intermediate layer, a mixed solvent of 80.75 parts by weight of methyl alcohol and 4.25 parts by weight of dipropylene glycol was mixed with rutile-type titanium oxide (TTOM-1 manufactured by Ishihara Sangyo). 10 parts by weight of a water-soluble copolymerized nylon resin as a binder resin (C
M8000) was dispersed for 8 hours using a paint shaker to obtain a coating solution for an intermediate layer. Table 1 shows the conditions for preparing the coating solution for the intermediate layer.

A laminated photoreceptor was prepared in the same manner as in Example 1, except that an intermediate layer was formed using the obtained coating solution for an intermediate layer, and image inspection and confirmation of electrical characteristics were performed. . The results obtained are shown in Table 2 together with the storage stability of the coating solution. After the formation of the intermediate layer, the film thickness was measured in the longitudinal direction (the pulling direction at the time of dip coating), and it was found that there was film thickness unevenness (dripping). FIG. 2 shows the film thickness profile. In Example 9, drying of the coating film of the coating solution for the intermediate layer was remarkably slow, and it was found that the productivity was extremely low.

Example 10 As a coating solution for the intermediate layer, 10 parts by weight of zinc oxide (manufactured by Sakai Chemical Co., SC-18) was mixed with a mixed solvent of 80.75 parts by weight of methyl alcohol and 4.25 parts by weight of methyl propylene glycol. And water-soluble copolymer nylon resin as binder resin (CM800, manufactured by Toray)
0) The mixture containing 5 parts by weight was subjected to a dispersion treatment for 8 hours using a paint shaker to obtain a coating liquid for an intermediate layer. Table 1
Shows the preparation conditions of the coating solution for the intermediate layer.

A laminated type photoreceptor was prepared in the same manner as in Example 1 except that an intermediate layer was formed using the obtained coating liquid for an intermediate layer, and image inspection and confirmation of electrical characteristics were performed. However, the electrical characteristics during repeated use, particularly the dark decay, were remarkably inferior. The results obtained are shown in Table 2 together with the storage stability of the coating solution.

Example 11 As a coating solution for the intermediate layer, an anatase-type titanium oxide (STT-65CS, manufactured by Titanium Industry Co., Ltd.) was added to a mixed solvent of 80.75 parts by weight of methyl alcohol and 4.25 parts by weight of methyl propylene glycol. A mixture of 5 parts by weight and 10 parts by weight of a water-soluble copolymer nylon resin (CM8000, manufactured by Toray Co., Ltd.) as a binder resin was subjected to a dispersion treatment using a paint shaker for 8 hours to obtain a coating liquid for an intermediate layer. Table 1 shows the conditions for preparing the coating solution for the intermediate layer. This coating solution for an intermediate layer had low storage stability, an increase in viscosity was observed 2 hours after preparation, and gelation was observed 1 day after preparation. Table 2 shows the storage stability of the coating solution.

Example 12 As a coating solution for the intermediate layer, a mixed solvent of 80.75 parts by weight of methyl alcohol and 4.25 parts by weight of methyl propylene glycol was mixed with rutile-type titanium oxide (TTOM-1 manufactured by Ishihara Sangyo). A mixture of 10 parts by weight and 5 parts by weight of PMMA (polymethyl methacrylate) as a binder resin was subjected to a dispersion treatment for 8 hours using a paint shaker to obtain a coating liquid for an intermediate layer. Table 1
Shows the preparation conditions of the coating solution for the intermediate layer. The coating liquid for the intermediate layer had low storage stability, and an increase in viscosity was observed 10 days after preparation. A laminated photoconductor was prepared in the same manner as in Example 1 except that an intermediate layer was formed using the obtained coating solution for an intermediate layer, and image inspection and confirmation of electrical characteristics were performed. The results obtained are shown in Table 2 together with the storage stability of the coating solution.

Example 13 As a coating solution for the intermediate layer, a mixed solvent of methyl alcohol (80.75 parts by weight) and methyl propylene glycol (4.25 parts by weight) was mixed with rutile-type titanium oxide (TTOM-1 manufactured by Ishihara Sangyo). A mixture of 5 parts by weight and 10 parts by weight of a water-soluble copolymer nylon resin (CM8000, manufactured by Toray Co., Ltd.) as a binder resin was subjected to a dispersion treatment using a paint shaker for 8 hours to obtain a coating liquid for an intermediate layer. Table 1 shows the conditions for preparing the coating solution for the intermediate layer.
This coating solution for an intermediate layer had low storage stability, and an increase in viscosity was observed one week after preparation.

Except that an intermediate layer was formed using the obtained coating solution for an intermediate layer, a laminated photoreceptor was manufactured in the same manner as in Example 1, and image inspection and confirmation of electrical characteristics were performed. However, a remarkable increase in the electrical characteristics, especially the residual potential, upon repeated use was observed. The results obtained are shown in Table 2 together with the storage stability of the coating solution.

[0088]

The coating solution for the intermediate layer according to the present invention comprises a mixed solvent comprising a monohydric alcohol of methanol or ethanol and a linear or branched dihydric alcohol having 1 to 5 carbon atoms as a solvent. Since it is used, there is little health problem, there is no problem such as viscosity increase or gelation over time, and brushing does not occur, and coating solution for photoconductor intermediate layer, and excellent repetition characteristics and environmental characteristics using it A photoreceptor can be provided.

By using methanol as the monohydric alcohol of the coating solution for the intermediate layer of the present invention, it is possible to provide a coating solution which not only has a high drying speed and improves mass productivity but also has excellent storage stability. By using methylpropylene glycol as the dihydric alcohol of the coating solution for the intermediate layer of the present invention, it is possible to provide a coating solution that prevents brushing and has excellent storage stability.

By using a mixed solvent containing a monohydric alcohol in a weight ratio higher than that of a dihydric alcohol, a coating liquid which not only prevents brushing but also has a moderately high drying speed and can enhance the mass productivity of the intermediate layer is provided. can do. The weight ratio of monohydric alcohol to dihydric alcohol is 9
By specifying 8/2 to 70/30, it is possible to provide a coating solution that prevents brushing and prevents unevenness in film thickness when forming the intermediate layer by dip coating.

By using water-soluble nylon as the binder resin of the coating solution for the intermediate layer of the present invention, a coating solution having excellent storage stability can be provided.

By including a metal oxide in the coating solution for an intermediate layer of the present invention, a photosensitive member having excellent repetition characteristics and environmental characteristics can be provided. Further, by using titanium oxide as the metal oxide, a photoreceptor having excellent repetition characteristics can be provided.

Further, by using rutile type titanium oxide, a photosensitive member having excellent storage stability can be provided. When the titanium oxide is contained more than the binder resin, a coating solution having excellent storage stability can be provided, and a photoreceptor having excellent repetition characteristics can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an example of a dip coating apparatus used in the present invention.

FIG. 2 is a graph showing the relationship (film thickness profile) between the distance from the upper end of a conductive substrate and the thickness of an intermediate layer in the photoconductors of Examples and Comparative Examples.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 dip coating device 2 conductive substrate 3 photosensitive layer 5 elevating ball screw 6 conductive substrate holding unit 7 coating speed control device 8 motor 9 coating liquid 10 coating tank 11 overflow tank 12 circulation path 13 stirring tank 14 circulation path 15 liquid feeding Pump 16 Circulation direction of coating liquid 17 Stirrer

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Rikiya Matsuo 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka Inside Sharp Corporation (72) Inventor Satoshi Katayama 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka (72) Inventor Yoshihide Shimoda 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka Sharp Corporation (72) Inventor Masaru Nakamura 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka Sharp Corporation F Terms (reference) 2H068 AA33 AA43 AA44 BA03 BB28 CA22 CA29 EA14

Claims (10)

[Claims] 1. A coating solution for forming an intermediate layer of an electrophotographic photoreceptor in which an intermediate layer and a photosensitive layer are sequentially formed on a conductive substrate, wherein the coating solution is a monohydric alcohol of methanol or ethanol; A coating solution for forming an intermediate layer of an electrophotographic photoreceptor, comprising a mixed solvent comprising a linear or branched dihydric alcohol represented by Formulas 1 to 5 and a binder resin. 2. The coating solution according to claim 1, wherein the dihydric alcohol is methyl propylene glycol. 3. The coating solution according to claim 1, wherein the monohydric alcohol is contained in a larger proportion than the dihydric alcohol by weight. 4. The coating solution according to claim 3, wherein the weight ratio between the monohydric alcohol and the dihydric alcohol is from 98/2 to 70/30. 5. The coating solution according to claim 1, wherein the binder resin is a water-soluble nylon. 6. The method according to claim 1, further comprising a metal oxide.
5. The coating liquid according to any one of 5. 7. The method according to claim 6, wherein the metal oxide is titanium oxide.
The coating solution according to the above. 8. The coating solution according to claim 7, wherein the titanium oxide is of a rutile type. 9. The coating liquid according to claim 7, wherein titanium oxide is contained in a larger proportion than the binder resin by weight. 10. An electrophotographic photoreceptor in which an intermediate layer and a photosensitive layer are sequentially formed on a conductive substrate, wherein the intermediate layer is formed by using the coating liquid according to any one of claims 1 to 9. An electrophotographic photoreceptor characterized in that: