JPH07234532A - Electrophotographic photoreceptor - Google Patents

Abstract

PURPOSE:To obtain an electrophotographic photoreceptor which is excellent in electric characteristics and image quality in repeated use, and has good productivity by providing an intermediate layer containing a specified component. CONSTITUTION:In an electrophotographic photoreceptor comprising a photosensitive layer 11 provided on a conductive substrate 1, the photosensitive layer 11 is formed by sequentially stacking an intermediate layer 2, a charge generation layer 3 and a charge transport layer 4 in order on the conductive substrate 1, and a compound expressed by the following formula is contained as an antioxidant in the intermediate layer 2 by 0.1-20%. In the formula, R1, R2 indicate an alkyl group with C1 to C12.

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 for electrophotography, and more particularly to an electrophotographic photosensitive member having an intermediate layer.

[0002]

2. Description of the Related Art A photoconductor for electrophotography (hereinafter referred to as a photoconductor) used in an electrophotographic apparatus starting from the invention of Carlson.
In the past, those using inorganic photoconductive materials such as selenium, selenium alloys, zinc oxide, and cadmium sulfide have been the mainstream. However, recently, development of a photoconductor using an organic photoconductive material has been actively promoted from the viewpoints of nontoxicity, film-forming property, lightweight property, low price and the like. Among them, a so-called function-separated laminated type organic photoconductor, which is divided into a charge generation layer that receives light in the photosensitive layer to generate charge carriers and a charge transport layer that moves the generated charge carriers, has each layer. The mainstream of development is that there are many advantages such as that sensitivity can be significantly improved by forming and combining layers of materials that are optimal for the function of the layer, and that spectral sensitivity can be increased according to the wavelength of the exposure light. Since then, it has been put into practical use and is being used in electrophotographic devices such as copiers and fax machines.

Currently, the mainstream of the functionally separated type organic photoconductors that have been put into practical use is a structure in which a photoconductive layer having a charge generation layer and a charge transport layer laminated in this order on a conductive substrate. In such a photoreceptor, an organic charge generating agent is sublimated or vapor-deposited on a conductive substrate, or a coating liquid in which the organic charge generating agent is dispersed and dissolved in an organic solvent together with a binder is applied and dried. Is formed by forming a charge transport layer. Basically, the basic performance as a photoconductor for image formation can be exhibited by such a layer structure. But,
Practically, it is important to obtain a good image without defects, and it is required that a good image 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 electric characteristics of the photoreceptor. Further, it is required that the film thickness and electrical characteristics are stable without being deteriorated even after long-term use.

By the way, the charge generation layer absorbs light to generate charge carriers, but the generated charge carriers move promptly without recombination and disappearance or trapping, and the conductive substrate or the charge. It needs to be injected into the transport layer. For this reason, it is desirable that the charge generation layer be as thin as possible, and in the currently practically used photoconductors, the charge generation layer having a thickness of submicron order is usually formed. Since the charge generation layer is formed as such a thin film, stains on the surface of the conductive substrate, non-uniformity in shape and properties, and roughness appear as film formation unevenness of the charge generation layer, resulting in an image obtained. There arises a problem that image defects such as white spots, black dots, and uneven density occur.
As the conductive substrate, an aluminum alloy drawn cylinder or a cylinder whose surface is smoothed by cutting and polishing is generally used, but it is included as a variation in surface roughness of the conductive substrate, stains, and alloy components. Due to variations in the amount and size of metal deposits and variations in surface texture due to variations in the degree of oxidation on the surface, film formation unevenness occurs in the charge generation layer formed on the surface, which can be obtained. This will have a major impact on the quality of the image. In order to prevent such unevenness of film formation and to obtain a blocking effect that prevents a decrease in charge retention of the photoconductor due to injection of holes from a conductive substrate, which is required separately, a conductive substrate An intermediate layer made of N-type resin having low electric resistance is provided on the surface.

On the other hand, a copy is usually obtained by repeating steps such as corona charging, exposure, development, transfer, cleaning and charge removal, but the photosensitive member is required to exhibit stable characteristics during that period. However, the function-separated type organic photoconductor has not been sufficiently satisfactory in terms of repeated stability life. That is, with repeated use, the chargeability is lowered and the residual potential is increased, resulting in a reduction in copy image quality. Various factors are considered to be the causes of these problems. Generally, when a photoconductor is used in a copying machine, it is always exposed to a corona discharge atmosphere, and deterioration thereof progresses under the influence of these gases. In particular ozone by a negative corona discharge, there is the generation of active gas such as NO _X, is greater their influence. As a method of preventing the deterioration of the photosensitive layer as described above, it has been proposed to add various antioxidants such as trialkylphenol derivatives and dilaurylthiopropionate to the photosensitive layer. (Japanese Patent Publication No. 50-33857, Japanese Patent Publication No. 51-34736, Japanese Patent Publication No. 56-130759, Japanese Patent Publication No. 57-12244).
issue)

[0006]

Resins such as solvent-soluble polyamide, polyvinyl alcohol, polyvinyl butyral, and casein are known as resins used for the intermediate layer. For the purpose of the blocking layer, these resins can sufficiently fulfill their functions even with an extremely thin film, for example, a thin film of 0.1 μm or less. However, for other purposes, that is, in order to prevent unevenness of film formation by coating the surface shape of the conductive substrate, variations in surface properties and surface stains, and improving non-uniformity of wetting of the charge generation layer coating liquid, 0.
A film thickness of 5 μm or more is required, and depending on the processing conditions of the conductive substrate and the state of surface contamination, depending on the case, 1
A film thickness of at least μm or several tens of μm is required. However, when the thick resin layer forming such an intermediate layer is formed of the above-mentioned polyvinyl alcohol solvent-soluble polyamide, casein, etc., the residual potential is increased, and the photoreceptor is exposed to the environment of low temperature and low humidity and high temperature and high humidity. There is a problem that the electric characteristics fluctuate. This problem is because the resin layer has a large water absorption property, and the electric conductivity of the resin layer is determined mainly by the movement of H ions and OH ions due to the dissociation of water absorbed in the resin layer, that is, the ion conduction. It occurs because it is liable to change depending on the water content contained in.

Such an intermediate layer has a low electric resistance,
Conventionally, various materials have been proposed as materials that have little change in electrical resistance even with changes in the surrounding environment. For example, regarding a solvent-soluble polyamide resin, the one that specifies the chemical structure of the polyamide resin is disclosed in JP-A-2-
193152, JP-A-3-288157,
JP-A-4-31870 is known, and
As an effect of adding an additive to a polyamide resin to suppress a change in electric resistance with respect to a change in environment, JP-B-2-59458, JP-A-3-150572, JP-A-2-53070, etc. It has been known. Further, as a mixture of a polyamide resin and another resin, which is expected to have an effect of adjusting electric resistance and weakening the influence of environmental changes, JP-A-3-145652 and JP-A-3-81778 disclose. Publication, JP-A-2-281
No. 262 publication is 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 (Japanese Patent Publication No. 4-22966, Japanese Patent Publication No. 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 an object thereof is to provide an intermediate layer containing a specific component. Accordingly, it is to provide an electrophotographic photosensitive member which is excellent in repeated electric characteristics and image quality and has good productivity.

[0011]

According to the present invention, in an electrophotographic photoreceptor having a photosensitive layer provided on a conductive substrate, the photosensitive layer comprises at least an intermediate layer, a charge generating layer and a charge transporting layer. This is achieved by laminating the compound on the conductive substrate in this order and containing 0.1 to 20% of the compound represented by the following general formula (I) as an antioxidant in the intermediate layer.

[0012]

[Chemical 2]

[In the formula, R ₁ and R ₂ represent a C ₁ to C ₁₂ alkyl group. The intermediate layer is a cured film containing a melamine resin, an aromatic carboxylic acid and / or an aromatic carboxylic acid anhydride, and iodine fixed to these as a main component. Further, it is effective that the intermediate layer is a cured film containing a normal butylated melamine resin, an acid and / or an acid equivalent, and iodine fixed thereto as a main component.

[0014]

When the photoconductor is repeatedly used, it is stressed by heat, ozone, strong light, etc., and especially the intermediate layer undergoes oxidative deterioration, transfer or injection of charges is blocked, and the residual potential increases and sensitivity decreases. Focusing on this, the theoretical elucidation has not yet been satisfactorily carried out through intensive research and experimentation on a method for preventing oxidative deterioration of the intermediate layer, but an alkylthio group-substituted triazine ring is incorporated into the molecule that is the antioxidant used in this invention. It has been discovered that the hindered phenols contained therein are particularly effective in preventing oxidative deterioration of the melamine resin.

The amount of the antioxidant added was 0.1 to 20% based on the total weight of the intermediate layer, which was determined from experimental values, and it was confirmed that 5 to 15% was the best.

[0016]

EXAMPLE The melamine resin according to the present invention means that melamine is subjected to methylolation and methylene condensation under an alkali catalyst in a large amount of butanol together with an excess of formaldehyde, and then subjected to butyl etherification under an acid catalyst. Is synthesized by. The degree of condensation varies depending on the amount of excess formaldehyde used and the strength of the alkali catalyst, but generally the number average molecular weight is 2000 to 400.
A condensate of 0 is formed. 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 has been known for a long time. For example, Uban (manufactured by Mitsui Toatsu Chemical), Super Beckamine (manufactured by Dainippon Ink and Chemicals).
It is marketed under the trade name such as. The aromatic carboxylic acid and the aromatic carboxylic acid anhydride are terephthalic acid, isophthalic acid, phthalic anhydride, trimellitic acid, trimellitic anhydride, pyromellitic acid, pyromellitic dianhydride, naphthalenecarboxylic acid and the like.

The total amount of aromatic carboxylic acid (anhydride) added to the melamine resin is preferably 5 to 100 parts by weight per 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 means melamine together with an excess of formaldehyde in a large amount of normal butanol under an alkali catalyst.
It is synthesized by methylolation and methylene condensation followed by butyl etherification in the presence of an acid catalyst.
Although the degree of condensation varies depending on the amount of excess formaldehyde used and the strength of the alkali catalyst used, a condensate having a number average molecular weight of 2000 to 4000 is generally 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. For example, Uban 20SB, 20HS, 2020, 2021 (manufactured by Mitsui Toatsu Kagaku Co., Ltd.), Super Pabeccamin J-820. -6
0, L-117-60, L-109-65 (manufactured by Dainippon Ink and Chemicals, Inc.) and the like.
The acid and the acid equivalent are a protic acid and a protic acid equivalent soluble in the normal butylated melamine resin solution, or a Lewis acid and a Lewis acid equivalent.

The protonic acid and the protonic acid equivalent are compounds which generate a proton (H ion) under the conditions of room temperature or under heating. Examples of organic substances include organic carboxylic acids and organic carboxylic acid equivalents, such as acetic acid, propionic acid, caproic acid, chloroacetic acid, malonic acid, acrylic acid, adipic acid, sebacic acid, dodecanedicarboxylic acid, terephthalic acid, isophthalic acid, fumaric acid. Organic carboxylic acids such as acid, itaconic acid, citraconic acid,
Examples thereof include acid anhydrides and ammonium salts. Others include organic sulfonic acids (eg paratoluene sulfonic acid, dodecylbenzene sulfonic acid, naphthalene-2-
Examples thereof include sulfonic acid) and ammonium salts thereof, and organic phosphoric acid (eg, methylphosphoric acid, propylphosphoric acid) and ammonium salts thereof. Further, as inorganic substances, sulfuric acid, phosphoric acid, hydrochloric acid, ammonium salts thereof (for example,
Ammonium sulfate, ammonium phosphate, ammonium chloride, etc.) can be mentioned.

As the Lewis acid, ammonium trichloride,
Examples thereof include boron trifluoride and trimethyl boron trichloride. The total amount of acid (equivalent) added to the normal butylated melamine resin is preferably 0.5 to 10 parts by weight with respect to 100 parts by weight of the normal butylated melamine resin. If the amount added is less than this, the degree of curing of the film will decrease, and problems such as swelling and dissolution of the film will occur when the charge generation layer is applied thereon, and if it is too large, the pot life of the coating liquid will be shortened. It is not preferable.

In the present invention, iodine is further fixed to 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). For this purpose, the mixed system is dissolved in a suitable solvent, and the solution contains 1% by weight to 20% of the mixed system.
Dissolve wt% iodine. The dissolved iodine is gradually adsorbed and added to the melamine resin and the aromatic carboxylic acid (anhydride) or to the normal butylated melamine resin, and this solution is applied on a substrate to form a coating film and heated. The iodine that is added and fixed when the cured film is formed is sublimated and removed without being fixed. If free iodine remains, the initial charge potential will decrease, the chargeability will decrease with repeated use, and the memory phenomenon will appear in the image. It is necessary to complete the 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 intermediate layer of the present invention contains melamine resin, an aromatic carboxylic acid (anhydride) and iodine, which are essential main components, or normal butylated melamine resin, an acid (equivalent), which is an essential main component. And iodine with 0.1 to 2 of the antioxidant of the general formula (I) based on the total weight of the intermediate layer.
0% (preferably 5 to 15%, if the addition amount is small, it has no effect, and if it is too large, it causes adverse effects such as increase in dark decay), a suitable solvent, for example, a mixed solvent of xylol and butanol, It is formed by dissolving and dispersing in chlormethane, methanol, tetrahydrofuran, etc. to prepare a coating solution, applying the coating solution on a conductive substrate by a spray method, a dipping method, etc. and heating and curing. Heating is usually
Temperature 80 ℃ -150 ℃, desirably 120 ℃ -140 ℃
20 minutes to 1 hour is sufficient.

The intermediate layer thus formed has a sufficiently low electric resistance and is stable, and even if the thickness of the intermediate layer is increased to 10 μm to 20 μm, the photoreceptor has excellent electric characteristics. Even if it is repeatedly used, there is almost no change in electrical characteristics such as a decrease in charge level, a decrease in sensitivity, and an increase in residual potential. Further, by forming such an intermediate layer of a thick film, variations in the properties of the conductive substrate surface, shape defects, variations in roughness, stains, etc. are covered, and a uniform photosensitive layer with few film defects is formed thereon. In particular, even in the case of a function-separated laminated type photoreceptor in which the photosensitive layer is laminated in order of the charge generation layer and the charge transport layer, a thin charge generation layer can be easily formed without causing unevenness in film formation. be able to. As a result, it is possible to obtain a photoconductor that can stably obtain a high-quality image with few image defects.

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 transport 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 solution dissolved in a suitable solvent together with a soluble binder resin such as polycarbonate, polyester, polystyrene, styrene acrylate is applied and dried to form a charge transport layer having a film thickness of 5 μm to 40 μm.

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. When this melamine resin was analyzed, it was found to have a number average molecular weight of 1,500, a melalol group of 1.7 and a butyl ether group of 2.0. A-2: Euban 62 (trade name: manufactured by Mitsui Toatsu Chemicals) (2) Aromatic carboxylic acid, aromatic carboxylic acid anhydride B-1: Phthalic acid B-2: Phthalic anhydride B-3: Trimellitic acid B-4: trimellitic anhydride B-5: pyromellitic acid B-6: pyromellitic anhydride (3) Normal butylated melamine resin C-1: 126 gr of melamine, 40 normal butanol
A mixed solution of 0 gr, 150 g of paraformaldehyde and 0.3 gr of a 1N hydrochloric acid aqueous solution was reacted for 2 hours while refluxing and dehydrating at a temperature of 100 ° C. to distill normal butanol to obtain a resin solution having a solid content of 50% by weight. . The normal butylated melamine resin thus obtained is designated as G-1. When this normal butylated melamine resin was analyzed, it was found to have a number average molecular weight of 1500, a methylol group of 1.7 and a butyl ether group of 2.0.

C-2: Uban 20HS (trade name: manufactured by Mitsui Toatsu Chemicals) (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) Antioxidant E-1: 2,4 Bis (n-offylthio) -4- (4-
Hydroxy-3,5-di-tert-butylanilino)
-1,2,3-Triazine (IRGANOX565: trade name: manufactured by Ciba Geigy) A specific example will be described with reference to FIG. FIG. 1 is a sectional structural view of a photoconductor showing an embodiment of the present invention. [Example 1] Outer diameter 30 mm, inner diameter 28 mm, length 250 mm,
The intermediate layer 2 is formed on the conductive substrate 1 having a maximum surface roughness Rmax of 1.0 μm. Coating materials T-1 to T-1 of Examples having the compositions shown in Table 1 using the materials A to E and a mixed solvent of xylene and butanol 1: 1 (parts by weight).
T-8 was compounded. Each of the coating liquids was applied onto the conductive substrate 1 by a dip coating method, dried by touch to the touch, and then baked and cured under the conditions shown in Table 2 to form U as the intermediate layer 2 of Example 1 shown in Table 2. -1 to U-8 were formed. For comparison, the coating liquids t-1 to t-3 of Comparative Example 1 having the compositions shown in Table 1 were used.
Were prepared, and each of the coating solutions was applied onto the conductive substrate 1 by a dip coating method to form u-1 to u- as the intermediate layer 2 of Comparative Example 1.
Formed 3.

On each conductive substrate 1 provided with the intermediate layer 2, 2.1 parts by weight of an azo compound represented by the following structural formula (II), polyvinyl acetal (manufactured by Sekisui Chemical Co., Ltd .: trade name "S-Rex K"
S-1 ") 1.0 part by weight is 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 is further added to the intermediate layer 2 for dip coating to obtain a dry thickness. 0.2 μm
The charge generation layer 3 was formed.

[0031]

[Chemical 3]

Next, a coating liquid consisting of 10 parts by weight of a hydrazone compound represented by the following structural formula (III), 10 parts by weight of a polycarbonate (trade name "Corpiron PCZ-300" manufactured by Mitsubishi Gas Chemical Co., Inc.), and 80 parts by weight of tetrahydrofuran is charged. It is applied by dip coating on the generation layer 3, and a charge transport layer 4 having a dry thickness of 20 μm is provided, and Examples 1-1 to 11 and Comparative examples 1-1 to 1-3 are provided.
Each of the photoconductors was prepared.

[0033]

[Chemical 4]

The photoconductor characteristics of each of the photoconductors thus produced were evaluated by a photoconductor process tester. The photoconductor is attached to a tester and rotated at a peripheral speed of 60 mm / s, charged to −600 V by a corotron, and the potential when no light is irradiated is defined as the dark part potential V ₀ . After that, the potential when left in the dark for 5 seconds was measured, and the potential holding ratio V _K5 during that period was measured.
Calculate (%). Then, the illuminance on the photoconductor is 30
Light from a halogen lamp is irradiated in the state of (lx), and the potential after 0.2 seconds is set as the bright portion potential V _L. The potential after irradiation for 1.5 seconds is defined as the residual potential Vr. The process of charging and exposing for one cycle as described above was repeated 10,000 times, and the characteristics of the photoconductor were measured after the initial (first) and 10,000 times. The results are shown in Table 3.

[0035]

[Table 1]

[0036]

[Table 2]

[0037]

[Table 3]

As is clear from Table 3, Comparative Examples 1-1 to 1-3 in which the intermediate layer 2 does not contain the antioxidant (E-1).
Shows a large decrease in charge and a large increase in residual charge. Next, the mounting characteristics were evaluated on a commercially available copying machine (manufactured by Sharp: product name "Z-30"). The initial dark potential (Vd) and bright potential ( _VL ) of the photoconductor are set to -700V and -100V, respectively, and the light intensity of the exposure light is changed to -100V from -700V.
The initial sensitivity is defined as the amount of light (lx · s) required to reach (1). Further, the potential when the light amount of 10 (lx · s) is exposed is defined as the initial residual potential (Vr).
Then, under the process conditions in which the initial characteristics were measured, the dark area potential (V
d), bright part potential (V _L ), sensitivity (lx · s) and residual potential (Vr) were measured to evaluate characteristic fluctuations during repeated use. The results are shown in Table 4.

[0039]

[Table 4]

As shown in Table 4, in Comparative Examples 1-1 to 1-3 in which the intermediate layer 2 does not contain the antioxidant (E-1), the residual potential drop due to repetition is large as compared with the Examples. The electric potential is also high. Next, the image quality of these photoconductors was evaluated at the initial stage and after the image was printed on 20,000 sheets. The results are shown in Table 5.

[0041]

[Table 5]

As can be seen from Table 5, the image quality of the photoconductor of the example is good, and even if the printing is repeated, the image quality of the photoconductor of the comparative example is not deteriorated and is stable. [Embodiment 2] Conductive substrate 1 having an outer diameter of 30 mm, an inner diameter of 28 mm, a length of 250 mm and a surface roughness of 1.0 μm at the maximum height Rmax.
The intermediate layer 2 is formed on top. Using the materials C, D, and E described above, and using a mixed solvent of xylene and butanol 1: 1 (parts by weight), the coating liquid T-9 of Composition Example 2 as shown in Table 6 was used.
To T-15 were blended, dried by touch to the touch, and baked and cured under the conditions shown in Table 7 to form U-9 to U-1 as the intermediate layer 2 of Example 2.
5 was formed. For comparison, a melamine resin other than the normal butylated melamine resin described below was used to prepare coating liquids t-4 to t-9 of Comparative Example 2 having the composition shown in Table 6, and the coating liquids were respectively prepared. It was applied onto the conductive substrate 1 by a dip coating method, dried by touch to the touch, and baked and hardened under the conditions shown in Table 7 to form u-4 to u-9 as the intermediate layer 2 of Comparative Example 2. (1) Isobutylated melamine resin a-1: Uban 62 (trade name: manufactured by Mitsui Toatsu Chemicals) a-2: Super Beckamine TD-139-60 (trade name: manufactured by Dainippon Ink and Chemicals) (2) Normal butyl Benzoguanamine resin a-3: Super Beckamine TD-126 (trade name: manufactured by Dainippon Ink and Chemicals) (3) Normal butylated benzoguanamine, melamine co-condensation resin a-4: Uban 91-55 (trade name: Mitsui Toatsu) Made by chemistry)

[0043]

[Table 6]

[0044]

[Table 7]

2.1 parts by weight of the disazo compound represented by the above structural formula (II), polyvinyl acetal (manufactured by Sekisui Chemical Co., Ltd .: trade name "Essless KS" is formed on each conductive substrate 1 provided with the intermediate layer 2.
-1 ") 1.0 part by weight was dispersed with 16 parts by weight of methylethylketone and 9 parts by weight of cyclohexanone by a n-d mill, and 75 parts by weight of methylethylketone was further added to the intermediate layer for dip coating to obtain a dry thickness. 0.2 μm
The charge generation layer of was formed. Next, the structural formula (III
10 parts by weight of the hydrazone compound and 80 parts by weight of tetrahydrofuran are applied by dip coating to obtain a dry thickness of 2
A charge transport layer 4 having a thickness of 0 μm is formed to form Examples 2-1 to 2-7.
And each photoconductor of Comparative Examples 2-1 to 2-6 was produced.

With respect to the thus prepared photoconductor, the photoconductor characteristics were evaluated by an optical process tester in the same manner as in Example 1. The results are shown in Table 8.

[0047]

[Table 8]

As is clear from Table 8, Comparative Examples 2-1 and 2-2 in which the intermediate layer 2 does not contain an antioxidant have large reductions in charge and increase in residual charge. In addition, other than the normal butylated melamine resins as in Comparative Examples 2-3 to 2-6, which contain an antioxidant, the initial potential holding property and residual potential are poor, and the characteristic variation during repeated use is remarkable. . Next, in the same manner as in Example 1, these photoconductors were attached to a commercially available copying machine (manufactured by Sharp: product name "Z-30") and evaluated for characteristics. The initial dark portion potential (Vd) and the light portion potential ( _VL ) of the photoconductor are set to -700V and -100V, respectively, and the light intensity required to reach -100V from -700V by changing the light intensity of the exposure light ( Let lx · s) be the initial sensitivity. The potential when the light amount of 10 (lx · s) is exposed is defined as the initial residual potential (Vr). Subsequently, after the static elimination process was repeated 20,000 times under the process conditions in which the initial characteristics were measured, the dark potential (Vd), the light potential ( _VL ),
The sensitivity (lx · s) and the residual potential (Vr) were measured, and the characteristic variation during repeated use was evaluated. The results are shown in Table 9.

[0049]

[Table 9]

As shown in Table 9, Comparative Examples 2-1 to 2-
In the case of No. 6, the decrease in charge was large with repetition, and the increase in the residual charge potential was large. Next, the image quality of these photoconductors was evaluated at the initial stage and when 20,000 sheets were printed. The results are shown in Table 10.

[0051]

[Table 10]

As can be seen from Table 10, the photoconductors of the examples have good image quality, and even if the environment is changed, and the repeated printing is performed, the image quality of the photoconductors of the comparative examples is hardly deteriorated and is stable. ing.

[0053]

According to the present invention, in an electrophotographic photoreceptor having an intermediate layer provided on a conductive substrate and a photosensitive layer provided thereon, the intermediate layer comprises a melamine resin and an aromatic carboxylic acid (anhydride). Or a cured film containing a normal butylated melamine resin and an acid (equivalent) with iodine as a main component,
Further, hindered phenols containing an alkylthio group-substituted triadi ring in the molecule are used as antioxidants. By having such an intermediate layer, it is possible to obtain a photosensitive member excellent in stability with less deterioration of charging characteristics and increase of residual potential even after repeated use. By forming such a thick film intermediate layer, various defects on the surface of the conductive substrate can be covered, and a uniform photosensitive layer with few film defects can be formed thereon. Even in the case of the functional type photoreceptor in which the charge generating layer and the charge transporting layer are laminated in this order, the thin charge generating layer can be easily formed without causing unevenness in film formation. As a result, it is possible to manufacture a photoconductor that can stably obtain a high-quality image with few image defects.

[Brief description of drawings]

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

[Explanation of symbols]

 1 Conductive Substrate 2 Intermediate Layer 3 Charge Generation Layer 4 Charge Transport Layer 11 Photosensitive Layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takashi Tanaka 1-1-1 Tanabe Nitta, Kawasaki-ku, Kawasaki-shi, Kanagawa Fuji Electric Co., Ltd.

Claims (3)

[Claims] 1. An electrophotographic photoreceptor comprising a photosensitive layer provided on a conductive substrate, wherein the photosensitive layer comprises at least an intermediate layer, a charge generating layer and a charge transport layer and is laminated on the conductive substrate in this order. The electrophotographic photoreceptor, wherein the intermediate layer contains the compound represented by the following general formula (I) as an antioxidant in an amount of 0.1 to 20%. [Chemical 1] [In the formula, R ₁ and R ₂ represent a C ₁ to C ₁₂ alkyl group. ] 2. The photoreceptor according to claim 1, wherein the intermediate layer comprises a melamine resin, an aromatic carboxylic acid and / or an aromatic carboxylic anhydride, and a curing agent containing iodine fixed thereto as a main component. An electrophotographic photoreceptor, which is a film. 3. The photoreceptor according to claim 1, wherein the intermediate layer is a cured film containing a normal butylated melamine resin, an acid and / or an acid equivalent, and iodine fixed thereto as a main component. An electrophotographic photoreceptor characterized by the following.