JPH07219260A - Electrophotographic photoreceptor - Google Patents

Abstract

PURPOSE:To obtain a photoreceptor excellent in electrical characteristics and image quality, almost independent of the external environment and having stability. CONSTITUTION:An intermediate layer 2 formed by laminating a blocking layer 22 based on alcohol-soluble polyamide resin on a hardened film 21 based on one of melamine resin and arom. carboxylic acid (anhydride) and iodine fixed to them, is interposed between an electrically conductive substrate 1 and a photosensitive layer 3. The blocking layer 22 may be laminated on the hardened film 21 based on one of n-butylated melamine resin and an acid (correspondent) and iodine fixed on them.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photosensitive member, and more particularly to an electrophotographic photosensitive member having a novel intermediate layer, which has excellent electrical characteristics and image quality and is stable.

[0002]

2. Description of the Related Art Electrophotographic photoconductors (hereinafter also simply referred to as photoconductors) used in electrophotographic apparatuses starting from the invention of Carlson have hitherto been inorganic photoconductive materials such as selenium, selenium alloys, zinc oxide, and cadmium sulfide. The mainstream was the use of materials. However, recently, in view of nontoxicity, film-forming property, light weight, low price and the like, development of a photoconductor using an organic photoconductive material has been actively promoted. Among them, a so-called function-separated laminated type organic photoconductor in which a photosensitive layer is divided into a charge generation layer that receives light to generate charge carriers and a charge transfer layer that moves generated charge carriers is used. It is a mainstream of development because it has many advantages such as being able to significantly improve the sensitivity by forming and combining it with a material optimal for the function of the layer, and being able to increase its spectral sensitivity according to the wavelength of the exposure light. It has been put into practical use and has been used in electrophotographic devices such as copiers, printers and fax machines.

The mainstream of the function-separated laminated type organic photoconductors currently in practical use is a structure in which a photoconductive layer having a charge generation layer and a charge transfer layer laminated in this order on a conductive substrate. . Such a photosensitive member is obtained by sublimating or vapor-depositing an organic charge generating agent on a conductive substrate, or coating and drying a coating liquid in which the organic charge generating agent is dispersed and dissolved in an organic solvent together with a binder. Then, a charge generating layer is formed, and subsequently, a coating liquid in which a charge transfer agent is dissolved in an organic solvent together with a binder is applied and dried to form a charge transfer layer. Basically, the basic performance as a photoreceptor for image formation can be exhibited with such a layer structure. However, it is practically important to obtain a good image free from defects, and it is required that a good image quality be maintained even after repeated use for a long period of time. For that purpose, it is necessary to form a photosensitive layer having a uniform and defect-free film quality and to have excellent electrical properties of the photoconductor. In addition, even if it is used for a long period of time, the film quality and electrical properties are not deteriorated and stable. Is required.

By the way, the charge generation layer absorbs light to generate charge carriers, but the generated charge carriers move quickly without recombination, disappearance, or trapping, and the conductive substrate or It needs to be injected into the charge transfer layer. For this reason, it is desirable to make the charge generation layer as thin as possible, and in the currently practiced photoreceptors, the charge generation layer having a film thickness of the submicron order is usually formed. Since the charge generation layer is formed as such a thin film, dirt on the surface of the conductive substrate,
The non-uniformity and roughness of the shape and properties appear as film formation unevenness of the charge generation layer as they are, resulting in a problem that image defects such as white spots, black spots, and density unevenness occur in the resulting image. As the conductive substrate, an aluminum alloy drawn cylinder or a cylinder whose surface is cut and polished to be smoothed is generally used as the conductive substrate, but the surface roughness variation of the substrate, surface contamination, and alloy components are included. Due to variations in the amount and size of metal deposits and variations in surface properties due to variations in the degree of surface oxidation, film formation unevenness occurs in the charge generation layer formed on the surface, resulting in an image Will have a great impact on the quality of.

In order to prevent such unevenness of film formation and to obtain a blocking effect for preventing a decrease in charge retention of the photoconductor due to injection of holes from a conductive substrate, which is required separately, a conductive property is obtained. An intermediate layer made of N-conductivity type resin having low electric resistance has been provided on the surface of a flexible substrate.

[0006]

As the resin used for the intermediate layer for such purpose, solvent-soluble polyamide, polyvinyl alcohol, polyvinyl butyral,
Resins such as casein are known. These resins are
An ultrathin film, for example, a thin film having a thickness of 0.1 μm or less, can sufficiently perform the above-mentioned purpose only for the purpose of a blocking layer. But for other purposes,
That is, in order to cover the surface shape of the conductive substrate, the variation of the surface properties and the surface stain, and to improve the non-uniformity of the wetting of the coating liquid for the charge generation layer to eliminate the unevenness of the film formation,
A film thickness of 1 μm or more is required, and depending on the processing conditions of the substrate and the state of surface contamination, a film thickness of 1 μm or more is required in some cases. However, when such a thick resin layer is formed from the above-mentioned polyvinyl alcohol, solvent-soluble polyamide, casein, etc., the residual potential rises, and the electrical characteristics of the photoconductor fluctuate in low-temperature low-humidity and high-temperature high-humidity environments. There was a problem that. This problem is due to the fact that the resin layer has a large water absorption property, and the electric conductivity of the resin layer is mainly determined by the movement of H ions and OH ions due to the dissociation of the water absorbed in the resin layer, that is, the ion conduction. It occurs because it is liable to change depending on the moisture contained in the layer.

Various materials have been conventionally proposed as materials suitable for the intermediate layer because the electric resistance of the layer having such a film thickness is low and the electric resistance thereof is small even when the surrounding environment changes. There is. For example, regarding a solvent-soluble polyamide resin, JP-A-2-193152, JP-A-3-288157, JP-A-4-31870 and the like are known to specify the chemical structure of the polyamide resin. In addition, as an effect expected to suppress a change in electric resistance due to a change in environment by adding an additive to a polyamide resin, JP-B-2-59458, JP-A-3-150572, and JP-A-2-530.
No. 70 publication is known. Further, a mixture of a polyamide resin and another resin is used to adjust the electric resistance and to expect an effect of weakening the influence of a change in the environment, as disclosed in JP-A-3-145652 and JP-A-3-817.
Japanese Patent Laid-Open No. 78 and Japanese Patent Laid-Open No. 2-281262 are known. However, the main material used in these methods is a polyamide resin, and the influence of temperature and humidity cannot be avoided.

An example of using a cellulose dielectric as a material other than the polyamide resin (Japanese Patent Laid-Open No. 2384/1990).
59), examples using polyether urethane (JP-A-2-115858, JP-A-2-280170), examples using polyvinylpyrrolidone (JP-A-2-
No. 105349), examples using polyglycol ether (Japanese Patent Laid-Open No. 2-79859), and the like, and from the idea that the amount of water in the resin layer does not depend on environmental changes. It is also proposed to use a crosslinkable resin, for example, an example using a melamine resin (JP-A-4-22966 and JP-B-4-31576).
Japanese Patent Publication No. 4-31577), an example using a phenol resin (Japanese Patent Laid-Open No. 3-48256), and the like are known. However, these methods are also effective when the resin layer is extremely thin, but when the film is relatively thick such as several μm, the resistance of the photoconductor becomes high, which causes an increase in residual potential.

As one of the methods for eliminating the above-mentioned drawbacks, it is conceivable that the material forming the intermediate layer is made to have electronic conduction instead of ionic conduction. As a method based on such an idea, a method of providing a resin layer in which a conductive powder such as tin oxide or indium oxide is dispersed has been proposed (Japanese Patent Publication No. 1-51185, Japanese Patent Publication No. 2185/1990).
-48175, Japanese Patent Publication No. 2-60177, Japanese Patent Publication No. 2-62861). However, even with such a method, there are many difficulties in preparing a resin coating solution in which the conductive powder is uniformly dispersed, and the coating solution should be stored stably so that the conductive powder does not separate or settle. However, it is inevitable that minute projections are often formed on the surface of the resin layer formed by applying the conductive powder due to separation and aggregation of the conductive powder, which causes image defects on the photoreceptor. Therefore, there has been proposed a method of forming an intermediate layer by using an organometallic compound instead of the above-mentioned conductive powder, and applying a coating liquid in which the organometallic compound is dissolved in an organic solvent together with a resin (Patent Publication 3). -4904, Japanese Patent Laid-Open No. 2-59767). However, this method also has an unstable coating liquid and has many problems to be solved in order to carry out industrial mass production.

The present invention has been made in view of various problems associated with a resin layer as an intermediate layer provided on a conductive substrate as described above, and two layers each containing a specific component are provided. Providing a photoreceptor with excellent electrical properties and image quality, stable electrical properties and image quality that are not easily affected by the external environment, and high productivity by providing an intermediate layer having a laminated structure The purpose is to do.

[0011]

According to the present invention, the above object is to provide an electrophotographic photosensitive member comprising an electroconductive substrate on which an intermediate layer is provided, and a photosensitive layer on the intermediate layer.
Melamine resin and aromatic carboxylic acid and / or aromatic carboxylic acid anhydride (hereinafter, simply aromatic carboxylic acid (anhydride)
(Also referred to as “()”) and iodine fixed thereto as a main component, and a blocking layer containing an alcohol-soluble polyamide resin as a main component is laminated on a cured film to form a two-layer structure.

Further, in an electrophotographic photoreceptor having an intermediate layer provided on a conductive substrate and a photosensitive layer provided thereon, the intermediate layer comprises a normal butylated melamine resin and an acid and / or an acid equivalent (hereinafter, simply Or a blocking layer containing an alcohol-soluble polyamide resin as a main component is laminated on a cured film containing any of the acids (also referred to as “equivalents”) and iodine fixed thereto as a main component. Will be resolved.

The thickness of the intermediate blocking layer is preferably 1 μm or less. In addition, a photosensitive layer having a function-separated laminated structure in which a charge transfer layer is formed on a charge generation layer can be favorably formed on such an intermediate layer. The melamine resin according to the present invention is a resin in which melamine is reacted with formaldehyde to form a methylol compound, which is further butyl etherified with an alcohol such as butanol or isobutanol.

Aromatic carboxylic acids and aromatic carboxylic anhydrides are terephthalic acid, isophthalic acid, phthalic anhydride, trimellitic acid, trimellitic anhydride, pyromellitic acid, pyromellitic anhydride, and naphthalenecarboxylic acid. And so on. The total amount of the aromatic carboxylic acid (anhydride) added to the melamine resin is preferably 5 parts by weight to 100 parts by weight with respect to 100 parts by weight of the melamine resin. If the addition amount is less than 5 parts by weight, the degree of curing of the film is lowered and the solvent resistance is lowered, and problems such as swelling and dissolution of the film occur when the charge generation layer is applied thereon,
If the amount is more than the weight part, the pot life of the coating liquid becomes short, which is not preferable.

The normal butylated melamine resin according to the present invention is a resin obtained by reacting melamine with formaldehyde to obtain a methylol compound, which is further converted to normal butyl ether with normal butanol. The acid and the acid equivalent are a protic acid and a protic acid equivalent soluble in the above-mentioned normal butylated melamine resin solution, or a Lewis acid and a Lewis acid equivalent.

The protic acid and the protic acid equivalent are compounds capable of generating a proton (H ion) under the conditions of room temperature and heating. As the organic substance, an organic carboxylic acid and an organic carboxylic acid anhydride,
For example, acetic acid, propionic acid, caproic acid, chloroacetic acid, malonic acid, acrylic acid, adipic acid, sevalic acid, dodecanedicarboxylic acid, terephthalic acid, isophthalic acid, trimellitic acid, pyromellitic acid, naphthalenecarboxylic acid, maleic acid, Examples thereof include fumaric acid, itaconic acid, citraconic acid, and other organic galbonic acids, and their acid anhydrides and ammonium salts. Others include organic sulfonic acids (eg, paratoluene sulfonic acid, dodecylbenzene sulfonic acid, nacfurin-2-sulfonic acid) and their ammonium salts, and organic phosphoric acids (eg, methyl lylic acid, propyl phosphoric acid) and their ammonium salts. Examples include salt. Inorganic substances include sulfuric acid, phosphoric acid, hydrochloric acid, and ammonium salts thereof (for example, ammonium sulfate,
Ammonium phosphate, ammonium chloride, etc.).

Examples of Lewis acids include aluminum trichloride, boron trifluoride, boron trimethylate and tin tetrachloride. The total amount of acid (equivalent) added to the normal butylated melamine resin is 0.5 to 10 parts by weight based on 100 parts by weight of the normal butylated melamine resin.
Parts by weight are the preferred range. If the addition amount is less than 0.5 parts by weight, the degree of curing of the film is lowered and the solvent resistance is lowered, and problems such as swelling and dissolution of the film occur when the charge generation layer is applied thereon. If the amount is more than 10 parts by weight, the pot life of the coating liquid becomes short, which is not preferable.

The alcohol-soluble polyamide resin according to the present invention includes nylon 6, nylon 66,
Examples thereof include nylon 610, nylon 11, nylon 12, copolymer nylons thereof, and N-methoxymethylated nylon. In the present invention, the cured film, which is a component of the intermediate layer, has a mixed system of a melamine resin and an aromatic carboxylic acid (anhydride), or a mixed system of a normal butylated melamine resin and an acid (equivalent), Further fix the iodine. For this purpose, the mixed system is dissolved in a suitable solvent, and 1% by weight to 20% by weight of iodine is dissolved in the solution. The dissolved iodine is gradually adsorbed and fixed to the melamine resin and aromatic carboxylic acid (anhydride) or to the normal butylated melamine resin, and then this solution is applied on the substrate to form a coating film and heated. Then, when the cured film is formed, it is additionally fixed, and iodine that is not fixed and is free is sublimated and removed. If free iodine remains, the initial charge level will decrease, the charging performance will decrease during repeated use, and the memory phenomenon will appear in the image. It is necessary to complete the curing reaction and to completely remove the free iodine. Whether free iodine remains can be determined and confirmed by immersing the cured film in methanol and extracting iodine into the methanol.

The cured film which is a constituent element of the intermediate layer of the present invention contains nuramine resin, aromatic carboxylic acid (anhydride) and iodine which are essential main components, or normal butylated melamine resin, acid (equivalent ) And iodine are dissolved and dispersed in an appropriate solvent such as a mixed solvent of xylol and butanol, dichlormethane, methanol, etc. to prepare a coating solution, and the coating solution is sprayed on a conductive substrate, dipping method, etc. It is formed by applying sufficient heat and curing so that free iodine does not remain. The heating is usually performed at a temperature of 80 ° C to 150 ° C, preferably 120 ° C to 13 ° C.
It is sufficient to perform the treatment at 0 ° C for 20 minutes to 1 hour.

The blocking layer, which is another component of the intermediate layer of the present invention, has a dry film thickness of 1 μm or less obtained by applying a coating solution prepared by dissolving an alcohol-soluble polyamide resin in methanol onto the cured film. It is formed as a coating film.
As described above, the present invention is particularly effective for a function-separated laminated type photoreceptor in which a photosensitive layer is laminated in order of a charge generation layer and a charge transfer layer. In such a photoreceptor, the charge generation layer is a coating liquid in which a pigment such as a phthalocyanine-based pigment, an anthrone pigment, a perylene pigment, a perinone pigment, an azo pigment, or a disazo pigment is dispersed in a solution in which an appropriate binder resin is dissolved. Is coated on the above-mentioned intermediate layer and dried to form a coating film having a film thickness of 0.1 μm to 1 μm, and an enamine compound, a hydrazone compound, a styryl compound, an amine compound, etc. are formed on the film as a phase mixture with these compounds. A coating liquid dissolved in a suitable solvent together with a soluble binder resin such as polycarbonate, polyester, polystyrene, styrene acrylate, etc. is applied and dried to form a charge transfer layer having a film thickness of 5 μm to 40 μm.

Here, the resin used for the intermediate layer of the present invention will be further described. (1) Melamine resin Melamine is synthesized by performing methylolation and methylene condensation under an alkali catalyst in a large amount of butanol together with an excess of formaldehyde, and then performing butyl etherification under an acid catalyst. The degree of condensation varies depending on the amount of excess formaldehyde used and the strength of the alkali catalyst used, but generally a condensate having a number average molecular weight of 2000 to 4000 is produced. When the reaction is carried out with only the acid catalyst from the beginning, a condensate having a number average molecular weight of about 1000 is obtained.

The melamine resin thus obtained is
It has been known for a long time, and is commercially available under the trade names of, for example, U-ban (manufactured by Mitsui Toatsu Chemicals, Inc.) and Super Beckamine (manufactured by Dainippon Ink and Chemicals, Inc.). (2) Normal Butylated Melamine Resin Melamine is subjected to methylolation and methylene condensation under an alkaline catalyst in a large amount of normal butanol together with an excess of formaldehyde, and then under an acid catalyst.
It is synthesized by performing butyl etherification. The degree of condensation varies depending on the amount of excess formaldehyde used and the strength of the alkali catalyst used, but generally a condensate having a number average molecular weight of 2000 to 4000 is produced. If the reaction is carried out only with an acid catalyst from the beginning, the number average molecular weight is 1000.
Front and rear condensates are obtained.

The normal butylated melamine resin thus obtained has been known for a long time, and examples thereof include Uban 20SB, Uban 20HS, Uban 2020, Uban 2021 (all manufactured by Mitsui Toatsu Kagaku Co., Ltd.), Superbecamine. J-820-60, Super Beckamine L-1
17-60, Super Beckamine L-109-65 (all manufactured by Dainippon Ink and Chemicals, Inc.) and the like are commercially available.

(3) Alcohol-Soluble Polyamide Resin Nylon 6 is synthesized by ring-opening polymerization of ε-caprolactam, and nylon 66 is synthesized by polycondensation of hexamethylenediamine and adipic acid. Copolymerized polyamide resin is desirable for this invention. . Such a resin is, for example, Amilan C.
M4000, Amylan CM4001, Amylan CM80
It is marketed under the trade name such as 00 (above Toray Co., Ltd.).

[0025]

[Function] A melamine resin is blended with either an aromatic carboxylic acid (anhydride) and cured by adding iodine to it, or a normal butylated melamine resin is blended with an acid (equivalent) However, the cured film obtained by adding iodine to this and fixing it has a sufficiently low electric resistance and is stable against changes in temperature and humidity. On the other hand, a layer containing an alcohol-soluble polyamide resin as a main component has a large temperature-humidity dependency of electric resistance, but has excellent blocking performance that suppresses injection of charge carriers from the substrate to the photosensitive layer, and even a thin layer is sufficiently blocked. Performance is obtained. The above-mentioned cured film is provided as a first layer on a conductive substrate to a thickness sufficient to cover defects such as stains on the surface of the substrate, unevenness in shape and properties, and roughness, for example, 10 μm to 20 μm. By using the above-mentioned blocking layer as a second layer thereon as a thin layer having a film thickness of 1 μm or less, an intermediate layer of a laminated structure is formed. Dirt etc. are covered, a uniform photosensitive layer with few film defects can be formed on it, electric resistance is sufficiently low, electric resistance is stable in a wide environmental range from high temperature high humidity to low temperature low humidity, In addition, an intermediate layer with excellent blocking performance is obtained, which has excellent electrical properties, and even when it is repeatedly used, changes in electrical properties such as a decrease in charge position, a decrease in sensitivity, and an increase in residual potential hardly occur, resulting in image defects. Less It is possible to obtain a photosensitive body obtained image quality stably. In particular, even in the case of a function-separated laminated type photoreceptor in which the photosensitive layer is laminated in the order of the charge generation layer and the charge transfer layer, a thin charge generation layer can be easily formed without causing unevenness in film formation.

[0026]

Embodiments of the present invention will be described below. [Example of Material Used for Intermediate Layer] In the examples, the following materials were used for forming the intermediate layer. (1) Melamine resin A-1: 126 g of melamine, 400 g of n-butanol
A mixture of 150 g of r, paraformaldehyde and 0.3 g of a 1N hydrochloric acid aqueous solution was reacted for 2 hours while refluxing and dehydrating at a temperature of 100 ° C. to distill n-butanol.
A resin liquid having a solid content of 50% by weight was obtained.

The melamine resin thus obtained is
-1. Analysis of this melamine resin revealed a number average molecular weight of 1500, a methylol group of 1.7 and a butyl ether group of 2.0. A-2: U-ban 62 (trade name; Mitsui Toatsu Chemicals, Inc.)
(2) Aromatic carboxylic acid, aromatic carboxylic anhydride B-1: phthalic acid B-2: phthalic anhydride B-3: trimellitic acid B-4: trimellitic anhydride B-5: pyromellitic Acid B-6: Pyromellitic dianhydride (3) Normal butylated melamine resin C-1: 126 g of melamine, 400 g of n-butanol
A mixture of 150 g of r, paraformaldehyde and 0.3 g of a 1N hydrochloric acid aqueous solution was reacted for 2 hours while refluxing and dehydrating at a temperature of 100 ° C. to distill n-butanol.
A resin liquid having a solid content of 50% by weight was obtained.

The melamine resin obtained in this way is treated with C
-1. Analysis of this melamine resin revealed a number average molecular weight of 1500, a methylol group of 1.7 and a butyl ether group of 2.0. C-2: Euban 20HS (trade name: manufactured by Mitsui Toatsu Chemicals, Inc.) (4) Acid and its equivalent D-1: Adipic acid D-2: Ammonium acetate D-3: Ammonium chloride D-4: Ammonium sulfate D-5: Ammonium phosphate D-6: Paratoluenesulfonic acid D-7: 3 Aluminum chloride (5) Alcohol-soluble polyamide E-1: Amilan CM8000 (trade name: Toray Industries, Inc.)
Production) Example 1, Comparative Example 1 [Formation of intermediate layer] A mixed solvent of xylene and butanol at a ratio of 1: 1 (parts by weight) was used, and the composition shown in Table 1 consisting of the materials A and B and iodine was used. The coating liquids F-1 to F-6 for the cured film as the first layer of the example and the coating liquid S-1 for the blocking layer as the second layer of the example made of the material E were prepared.

[0029]

[Table 1]

Outer diameter 30 mm, inner diameter 28 mm, length 26
0.5 mm, the surface roughness maximum height R _{ma x} at 1.0μm aluminum cylinder on, coating solution F-1 to F-6 were coated with each dip coating method, after tack, Table 2 By baking and curing under the conditions shown, a cured film having a film thickness of 10 μm to 20 μm is formed as a first layer, and subsequently, the coating liquid S-1 is formed on the first layer.
Was applied by a dip coating method, dried by touch to the touch, and baked and cured under the conditions shown in Table 2 to form a blocking layer having a film thickness of 1 μm or less as a second layer. The intermediate layer U-1 of Example 1
~ U-6 was formed.

For comparison, as shown in Table 2,
The thickness of the second blocking layer of the intermediate layer U-1 is set to 1.5.
Intermediate layer u-1 and intermediate layer U- of Comparative Example 1 thickened to 0 μm
1, U-4, which is a single layer of the intermediate layers u-2 and u-3 of Comparative Example 1, which does not form a blocking layer, and which does not form a cured film of the first layer, and only the blocking layer of the second layer. Contrary to the single-layered intermediate layer u-4 and the intermediate layers U-1 and U-4 of Comparative Example 1, a block layer was used as a first layer and a cured film was formed thereon as a second layer. Intermediate layers u-5 and u-6 were formed.

[0032]

[Table 2]

[Production of Photoreceptor] 2.1 parts by weight of an azo compound having the following structural formula and polyvinyl acetal (manufactured by Sekisui Chemical Co., Ltd .; trade name) were placed on each aluminum cylinder provided with the intermediate layer as described above. 1.0 part by weight of "Eslex KS-1") was dispersed in a sand mill together with 16 parts by weight of methyl ethyl ketone and 9 parts by weight of cyclohexanone, and 75 parts by weight of methyl ethyl ketone was further added for dip coating to obtain a dry thickness of 0. A 2 μm charge generation layer was formed.

[0034]

[Chemical 1]

Subsequently, a hydrazone compound 1 having the following structural formula
0 parts by weight, polycarbonate resin (Mitsubishi Gas Chemical Co., Inc.)
Manufactured by trade name "Iupilon PCZ-300") 10 parts by weight and 80 parts by weight of tetrahydrofuran are applied onto the charge generation layer by dip coating to form a charge transfer layer having a dry thickness of 20 μm. 1-1-6 and Comparative Example 1
Each of the photoconductors -1 to 1-6 was produced.

[0036]

[Chemical 2]

[Evaluation of Photoreceptor] The photoconductor characteristics of each of the photoconductors thus produced were evaluated with a photoconductor process tester. The photoconductor is attached to the tester and the peripheral speed is 60 mm
While being rotated at a speed of about 1 sec / sec, it is charged to −600 v by a corotron, and the potential when no light is irradiated is defined as the dark part potential V _d (v). After that, the potential when left in the dark for 5 seconds is measured, and the potential holding ratio V _K5 (%) during that period is obtained. Subsequently, a halogen lamp is irradiated with 30 lux of light, and the potential after 0.2 seconds is set as the bright portion potential V _l (v). Furthermore, 1.5
The potential after second irradiation is defined as the residual potential V _r (v). The process of charging and exposing in one cycle as described above
After repeating 10,000 times, the characteristics of the photoconductor were measured at the initial stage (first time) and after repeating 10,000 times. The results are shown in Table 3.

[0038]

[Table 3]

As can be seen from Table 3, Comparative Examples 1-2 and 1-in which the intermediate layer is only the cured film which is the first layer of the present invention.
The photoconductor of No. 3 and the photoconductors and intermediate layers of Comparative Examples 1-5 and 1-6 in which the order of laminating the first layer and the second layer of the intermediate layer are opposite to those of the photoconductors of Examples are the second of the invention. The photoreceptor of Comparative Example 1-4 including only the blocking layer, which is a layer, shows a large decrease in charge and an increase in residual potential after repeating 10,000 times and a large fluctuation in V _l , as compared with the photoreceptor of the example. Further, even if the intermediate layer has the same stacking order as that of the photoreceptor of the example, the photoreceptor using the second layer, that is, the intermediate layer having a thick blocking layer is found in the photoreceptor of Comparative Example 1-1. In addition, the electrical characteristics are inferior to the photoconductors of the examples.

Further, the characteristics of these photoconductors are measured in a low temperature and low humidity environment (LL; temperature 10 ° C., relative humidity 50%) and a high temperature and high humidity environment (H, H; temperature 35 ° C., relative humidity 85%). And examined its environmental dependence. The results are shown in Table 4.

[0041]

[Table 4]

As is clear from Table 4, each of the photoconductors of the examples has less variation in characteristics with respect to environmental changes and is more stable than each of the photoconductors of the comparative examples. Next, a commercially available copying machine (manufactured by Sharp Corporation; trade name "Z-30") is used for these photoconductors.
It was attached to and evaluated for characteristics. The initial dark portion potential V _d (v) and the light portion potential V _l (v) of the photoconductor are set to −700, respectively.
v, -100v, changing the intensity of the exposure light to -7
The initial sensitivity E (lux · s) is defined as the amount of light required to reach −100 v from 00 v. The initial residual potential V _r (v) is defined as the potential when the light of 10 lux · s is exposed. Subsequently, under the process conditions in which the initial characteristics were measured, the dark part potential V _d , the light part potential V _l , and the sensitivity E after the charging / discharging process was repeated 20,000 times were measured to evaluate the characteristic variation during repeated use. did. The results are shown in Table 5.

[0043]

[Table 5]

As can be seen from Table 5, Comparative Examples 1-2 and 1-in which the intermediate layer consisted only of the cured film as the first layer of the present invention.
The photoconductor of No. 3 has a large decrease in the dark part potential after repeating 20,000 times as compared with the photoconductor of the example. Further, Comparative Example 1-4 in which the intermediate layer is composed only of the blocking layer which is the second layer of the present invention.
The photoreceptor has a large increase in the light-area potential after repeating 20,000 times. Further, the photoreceptors of Comparative Examples 1-5 and 1-6, in which the order of laminating the first layer and the second layer of the intermediate layer was the reverse of the photoreceptor of the example, had a high residual potential, and after repeating 20,000 times. The residual potential is particularly high as compared with other photoconductors, and the decrease in dark part potential and the increase in bright part potential are large after 20,000 repetitions. Further, even if the intermediate layer has the same stacking order as that of the photoreceptor of the example, if the thickness of the second layer, that is, the blocking layer is large, the residual potential is high as seen in the photoreceptor of Comparative Example 1-1, The increase in the bright part potential after repeating 20,000 times is also large.

Next, with respect to these photoconductors, a low temperature and low humidity environment (LL) and a normal temperature and normal humidity environment (N.
N; temperature 25 ° C., relative humidity 50%), and high-temperature high-humidity environment (H.H.), respectively, and the image quality was evaluated at the initial stage and after copying 20,000 sheets. The results are shown in Table 6.

[0046]

[Table 6]

As can be seen from Table 6, the image quality of the photoconductors of the examples is good, and the image quality of the photoconductors of the comparative examples does not deteriorate even when the environment changes or when copying is repeated. It hardly happens and is stable. Example 2 and Comparative Example 2 [Formation of Intermediate Layer] Example in which a mixed solvent of xylene and butanol at a ratio of 1: 1 (part by weight) was used, and the composition of the materials C and D and iodine as shown in Table 7 was used. The coating liquids F-7 to F-13 for the cured film of the first layer of No. 2 were prepared. For comparison, coating liquids f-1 to f-4 for the first layer of Comparative Example 2 having the same composition as shown in Table 7 were prepared. here,
The materials used for the first layer cured film coating solution of Comparative Example 2 are as follows.

(1) Isobutylated melamine resin a-1: Uban 62 (trade name: Mitsui Toatsu Chemicals, Inc.)
A-2: Super Beckamine TD-139-60 (trade name: manufactured by Dainippon Ink and Chemicals, Inc.) (2) Normal butylated benzoguanamine resin a-3: Super Beckamine TD-126 (trade name: large) (Nippon Ink Chemical Co., Ltd.) (3) Normal butylated benzoguanamine, melamine co-condensation resin a-4: Uvan 91-55 (trade name: Mitsui Toatsu Chemical Co., Ltd.)

[0049]

[Table 7]

Each of the coating liquids F-7 to F-13 was applied onto the same aluminum cylinder as in Example 1 by the dip coating method, dried by touching with fingers, and then baked and cured under the conditions shown in Table 8. To form a cured film having a film thickness of 5 μm to 10 μm as a first layer, and subsequently apply the same coating liquid S-1 as that used in Example 1 to each of the first layers by a dip coating method, After being dried by touch, it was baked and cured under the conditions shown in Table 8 to a film thickness of 0.
A 5 μm blocking layer was formed as the second layer to form the intermediate layers U-7 to U-13 of Example 2.

For comparison, each of the coating liquids f-1 to f-4 for the first layer of Comparative Example 2 was applied onto the same aluminum cylinder as in Example 1 by the dip coating method. After being dried to the touch, it was baked and cured under the conditions shown in Table 8 to give a film thickness of 5
A cured film having a thickness of μm is formed as a first layer, and subsequently, the same coating liquid S-1 as that used in Example 1 is applied onto each of the first layers by a dip coating method. The intermediate layers u-7 to u-10 of Comparative Example 2 were formed by baking and curing under the conditions shown in FIG. 8 to form a blocking layer having a thickness of 0.5 μm as a second layer.
Was formed.

[0052]

[Table 8]

[Production of Photoreceptor] Using each aluminum cylinder provided with the above-mentioned intermediate layer, in the same manner as in Example 1,
The photoconductors of Examples 2-1 to 2-7 and Comparative examples 2-1 to 2-4 were produced. [Production of Photoreceptor] With respect to each of the photoreceptors thus produced, the characteristics of the photoreceptor were evaluated in the same manner as in Example 1 using a photoreceptor process tester. The results are shown in Table 9.

[0054]

[Table 9]

As can be seen from Table 9, the photoconductor of the comparative example in which a resin other than the normal butylated melamine resin was used as the resin used for the cured film as the first intermediate layer, the initial sensitivity, potential holding property, The residual potential is poor, and the characteristics change significantly during repeated use over a long period of time. Further, the characteristics of these photoconductors were measured in a low temperature and low humidity environment (L, L) and a high temperature and high humidity environment (H, H), and their environment dependence was investigated. The results are shown in Table 10.

[0056]

[Table 10]

As can be seen from Table 10, the photoconductor of the example using the normal butylated melamine resin in the cured film of the first intermediate layer was the photoconductor of the comparative example using the resin other than the normal butylated melamine resin. Compared with the above, it is excellent in that there is little change in characteristics due to changes in the environment. Then, in the same manner as in Example 1, these photoconductors were put on a commercially available copying machine (Sharp Corp.).
Made: Product name "Z-30") attached to evaluate the characteristics,
In addition, the characteristic variation during repeated use was evaluated. The results are shown in Table 11.

[0058]

[Table 11]

As shown in Table 11, Comparative Examples 2-1 to 2-1
In the case of the photosensitive member No. 2-4, the charge is decreased repetitively and the bright portion potential and the residual potential are also increased. Next, in the same manner as in Example 1, a low temperature and low humidity environment (L, L), a normal temperature and normal humidity environment (N,
N) and the high-temperature and high-humidity environment (H, H) were evaluated for image quality at the initial stage and after copying 20,000 times, respectively. The results are shown in Table 12.

[0060]

[Table 12]

As can be seen from Table 12, the image quality of each of the photoconductors of the examples is good, and the image quality of the photoconductor of the comparative example is not deteriorated even when the environment is changed or when copying is repeated. It hardly happens and is stable.

[0062]

According to the present invention, in an electrophotographic photosensitive member comprising a conductive substrate and an intermediate layer provided thereon and a photosensitive layer provided thereon, the intermediate layer comprises a melamine resin and an aromatic carboxylic acid (anhydride). ) And iodine fixed to these as a main component on a cured film, or containing either a normal butylated melamine resin and an acid (equivalent) and iodine fixed to these as a main component. The cured film has a two-layer structure in which a blocking layer containing an alcohol-soluble polyamide resin as a main component is laminated.

The cured film as described above has a sufficiently low electric resistance and is stable against changes in temperature and humidity. On the other hand, a layer containing an alcohol-soluble polyamide as a main component has a large temperature-humidity dependency of electric resistance, but has excellent blocking performance for suppressing injection of charge carriers from the substrate to the photosensitive layer, and sufficient blocking performance even in a thin layer. Is obtained. Therefore, the above-mentioned cured film on the conductive substrate does not cause a problem of increasing the electric resistance of the photoconductor, and has a film thickness sufficient to cover defects such as stains on the surface of the substrate, unevenness in shape and properties, and roughness. , For example, a film thickness of 5 μm to 20 μm can be provided, and the blocking layer described above is provided as a thin layer thereon to form an intermediate layer of the laminated structure. It is possible to form a uniform photosensitive layer with few film defects on which roughness variations, dirt, etc. are covered, and the electric resistance is sufficiently low, and the electric resistance is wide in a wide environmental range from high temperature and high humidity to low temperature and low humidity. An intermediate layer that is stable and has excellent blocking performance can be obtained. The thickness of the blocking layer is preferably 1 μm or less. By forming a photosensitive layer on the intermediate layer of such a laminated structure, it has excellent electric characteristics, and even if it is repeatedly used, the electric characteristics hardly change,
It is possible to obtain a photoconductor that can stably obtain a high-quality image with few image defects. In particular, even in the case of a function-separated layered type photoconductor in which the photosensitive layer is laminated in order of the charge generation layer and the charge transfer layer, it is necessary to generate a thin film of the charge generation layer on the intermediate layer. It is preferable because it can be easily formed.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of an embodiment of a photoconductor of the present invention.

[Explanation of symbols]

 1 Conductive Substrate 2 Intermediate Layer 3 Photosensitive Layer 21 Cured Film 22 Blocking Layer 31 Charge Generation Layer 32 Charge Transfer Layer

Claims (4)

[Claims] 1. An electrophotographic photoreceptor comprising an electroconductive substrate having an intermediate layer provided thereon and a photosensitive layer provided thereon, wherein the intermediate layer comprises a melamine resin and an aromatic carboxylic acid and / or an aromatic carboxylic anhydride. An electrophotographic photoreceptor having a two-layer structure in which a blocking layer containing an alcohol-soluble polyamide resin as a main component is laminated on a cured film containing any of these and iodine fixed to these as a main component. 2. An electrophotographic photoreceptor comprising an electroconductive substrate having an intermediate layer provided thereon and a photosensitive layer provided thereon, wherein the intermediate layer comprises a normal butylated melamine resin and an acid and / or an acid equivalent thereof. An electrophotographic photosensitive member having a two-layer structure in which a blocking layer containing an alcohol-soluble polyamide resin as a main component is laminated on a cured film containing iodine fixed as a main component. 3. The electrophotographic photosensitive member according to claim 1, wherein the thickness of the intermediate blocking layer is 1 μm or less. 4. A photosensitive layer comprising a charge generation layer and a charge transfer layer formed on the charge generation layer.
The electrophotographic photosensitive member according to any one of 1.