JP2618054B2 - Electrophotographic photoreceptor and manufacturing method thereof - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photosensitive member used in an image forming apparatus such as a copying machine and a method for producing the same.

<Related Art> In recent years, in an image forming apparatus such as a copying machine using a so-called Carlson process, a charge generating material that generates charges by light irradiation and a charge transporting material that transports generated charges are used in combination. By separating the charge generation function and the charge transport function, so-called function separation type,
It is widely used because it is easy to increase the sensitivity. As the function-separated type photoreceptor, a laminated photosensitive layer including a charge generation layer containing the above-described charge generation material and a charge transport layer containing the charge transport material was formed on the surface of a conductive substrate. There are a laminate type and a single layer type in which a single layer type photosensitive layer containing a charge generation material and a charge transport material is formed on the surface of a conductive substrate.

Further, in the function-separated type photoreceptor, the entirety of the single-layer or stacked-type photosensitive layer formed on the surface of the conductive substrate is formed by bonding the functional components such as the charge generation material and the charge transport material to a binder resin. An organic photoreceptor with an organic layer contained therein,
A composite type photoreceptor having a part of the above-mentioned laminated type photosensitive layer and the above-mentioned organic layer is preferably used for a wide selection of materials, excellent productivity, and a high degree of freedom in functional design. I have.

Further, recently, when an image forming process such as charging, exposure, and static elimination is repeatedly performed, the organic layer in the organic photoconductor or the composite photoconductor may be fatigued to cause a reduction in charge amount or a reduction in sensitivity. In addition to the ordinary charge transporting material, m is excellent in preventing action such as the decrease in the amount of charge and the decrease in sensitivity.
Photoreceptors containing a phenylenediamine compound as a charge transport material have been proposed.

<Problems to be Solved by the Invention> However, the photoreceptor containing the m-phenylenediamine compound is particularly suitable for a fluorescent lamp or a xenon lamp when the photoreceptor is heated, for example, during operation of an image forming apparatus. Alternatively, when irradiated with sunlight or the like, there is a problem in that the sensitivity is reduced due to ultraviolet rays contained in these lights.

In addition, the sensitivity is reduced by the above-mentioned UV irradiation (UV deterioration).
Forms a layer containing the m-phenylenediamine compound from a coating solution using tetrahydrofuran (THF) as a solvent or a dispersion medium, which is particularly excellent in volatility and is frequently used in the production of organic photoreceptors. Was remarkable.

The present invention has been made in view of the above circumstances, and contains an m-phenylenediamine-based compound which is excellent in the action of preventing a decrease in charge amount or sensitivity when an image forming process is repeatedly performed. Further, it is an object of the present invention to provide an electrophotographic photoreceptor which is hardly deteriorated by ultraviolet rays and a method for producing the same.

<Means and Actions for Solving the Problems> In order to solve the above problems, the inventors examined the relationship between the amount of THF remaining in the formed layer and the reduction in sensitivity.

That is, in the ultraviolet degradation, the m-phenylenediamine-based compound is excited by its own ultraviolet absorption or energy transfer from the ultraviolet absorbing substance of the charge generation material, causing a dimerization reaction or a decomposition reaction to cause the photoreceptor to degrade. It is thought to be due to the change to a substance that acts as a carrier trap that lowers the sensitivity.
F was also studied assuming that F was involved in the dimerization reaction and decomposition reaction of the m-phenylenediamine compound as the ultraviolet absorbing substance.

As a result, it has been found that an image having no practical problem can be obtained if the amount of residual THF is 2.5 × 10 ⁻³ μ / mg or less, and the present invention has been completed based on this finding. Therefore, the electrophotographic photoreceptor of the present invention has an electrophotographic photoreceptor having a layer formed by applying a coating solution containing a binder resin, an m-phenylenediamine compound as a charge transport material, and THF. In the body, the amount of residual THF in the layer is previously set to 2.5 × 10 ⁻³ μ / mg or less, and the method for producing an electrophotographic photoreceptor of the present invention comprises a binder resin and a charge generation material. M-phenylenediamine compound and a layer formed by applying a coating solution containing THF is heat-treated at a temperature of 110 ° C. or more for 30 minutes or more to reduce the amount of residual THF in the layer to 2.5 × 10 ^−3. It is characterized in that it is not more than μ / mg.

 Hereinafter, the present invention will be described in detail.

The structure of the present invention includes various types including an organic layer formed by applying a coating solution containing a binder resin, an m-phenylenediamine compound, and THF (hereinafter, referred to as a “specific layer”). The specific layer includes, for example, the following layers.

A single-layer organic photosensitive layer containing a charge generation material and a charge transport material in a binder resin.

The charge transport layer in a stacked organic photosensitive layer in which an organic charge generation layer and an organic charge transport layer are laminated.

The charge transport layer in a composite photosensitive layer in which a charge generation layer composed of a thin film of a semiconductor material and an organic charge transport layer are laminated.

The m-phenylenediamine compound contained in the specific layer is represented by the following general formula [I].

(However, R ^{1 to} R ⁵ in the above formula [I] each represent the same or different groups selected from the group consisting of an alkyl group, an alkoxy group, a halogen atom and a hydrogen atom.) The m-phenylenediamine-based compound As a preferable example, a compound in which the groups R ^{1 to} R ⁵ in the formula [I] are hydrogen, a lower alkyl group having 1 to 6 carbon atoms, a lower alkoxy group having 1 to 6 carbon atoms, or halogen is mentioned. Can be
Examples of the lower alkyl group include a methyl group, an ethyl group, a normal propyl group, an isopropyl group, a normal butyl group, an isobutyl group, a tert-butyl group, a pentyl group, and a hexyl group.Examples of the lower alkoxy group include a methoxy group, Ethoxy group, normal propoxy group, isopropoxy group, normal butoxy group, isobutoxy group, tert-
Examples include a butoxy group, a pentyloxy group, and a hexyloxy group.

Specifically, N, N, N ', N'-tetraphenyl-1,3-phenylenediamine, N, N, N', N'-tetrakis (3-tolyl) -1,3-phenylenediamine, N , N, N ', N'-tetraphenyl-3,5-tolylenediamine, N, N, N', N'-tetrakis (3-tolyl) -3,5-tolylenediamine, N,
N, N ', N'-tetrakis (4-tolyl) -1,3-phenylenediamine, N, N, N', N'-tetrakis (4-tolyl)
-3,5-tolylenediamine, N, N, N ', N'-tetrakis (3-ethylphenyl) -1,3-phenylenediamine,
N, N, N ', N'-tetrakis (4-propylphenyl)-
1,3-phenylenediamine, N, N, N ', N'-tetraphenyl-5-methoxy-1,3-phenylenediamine, N, N-bis (3-tolyl) -N', N'-diphenyl- 1,3-phenylenediamine, N, N'-bis (4-tolyl) -N, N'-
Diphenyl-1,3-phenylenediamine, N, N'-bis (4-tolyl) -N, N'-bis (3-tolyl) -1,3-phenylenediamine, N, N'-bis (4-tolyl ) −N, N ′
-Bis (3-tolyl) -3,5-tolylenediamine, N, N '
-Bis (4-ethylphenyl) -N, N'-bis (3-ethylphenyl) -1,3-phenylenediamine, N, N'-bis (4-ethylphenyl) -N, N'-bis (3 -Ethylphenyl) -3,5-tolylenediamine, N, N, N ', N'-tetrakis (2,4,6-trimethylphenyl) -1,3-phenylenediamine, N, N, N', N '-Tetrakis (2,4,6-trimethylphenyl) -3,5-tolylenediamine, N, N, N',
N'-tetrakis (3,5-dimethylphenyl) -1,3-phenylenediamine, N, N, N ', N'-tetrakis (3,5-dimethylphenyl) -3,5-tolylenediamine, N, N, N ′,
N'-tetrakis (3,5-diethylphenyl) -1,3-phenylenediamine, N, N, N ', N'-tetrakis (3,5-diethylphenyl) -3,5-tolylenediamine, N, N, N ′,
N'-tetrakis (3-chlorophenyl) -1,3-phenylenediamine, N, N, N ', N'-tetrakis (3-bromophenyl) -1,3-phenylenediamine, N, N, N', N '-
Tetokis (3-iodophenyl) -1,3-phenylenediamine, N, N, N ', N'-tetrakis (3-fluorophenyl) -1,3-phenylenediamine and the like are preferred m-phenylenediamine compounds. Can be And
Among the above compounds, the groups R ^{1 to} R ^{5 in the} general formula (I)
Is a compound bonded to the carbon at the meta-position to the carbon to which the nitrogen atom is bonded in each benzene ring, or a group
R ¹ and R ⁵ are bonded to the carbon at a position para to the carbon to which the nitrogen atom is bonded in the benzene ring, and the groups R ² and R ⁴ are bonded to the nitrogen atom in the benzene ring. The compound bonded to the carbon at the meta position with respect to the carbon that has a high degree of molecular asymmetry, small interaction between the molecules and difficult to crystallize, can be easily dispersed in the binder resin. To
More preferable examples are given. Specifically, N, N,
N ', N'-tetrakis (3-tolyl) -1,3-phenylenediamine, N, N'-bis (4-tolyl) -N, N'-bis (3-tolyl) -1,3-phenylenediamine And the like are exemplified as more preferable.

On the other hand, as the binder resin constituting the photosensitive layer together with the m-phenylenediamine compound, for example, a thermosetting silicone resin; an epoxy resin; a urethane resin; a curable acrylic resin; an alkyd resin;
Diallyl phthalate resin; phenolic resin; urea resin;
Benzoguanamine resin; Melamine resin; Styrene polymer; Acrylic polymer; Styrene-acrylic copolymer; Olefinic polymer such as polyethylene, ethylene-vinyl acetate copolymer, chlorinated polyethylene, polypropylene, ionomer, etc .; Vinyl; vinyl chloride-vinyl acetate copolymer; polyvinyl acetate; saturated polyester; polyamide; thermoplastic urethane resin; polycarbonate such as bisphenol A type, bisphenol Z type; polyarylate; polysulfone; ketone resin; polyvinyl butyral; Is mentioned. In addition, the binder resin is, in addition to the specific layer, a charge generation layer of a laminated organic photosensitive layer, and a surface protective layer formed as needed on the outermost layer of each type of photosensitive layer. It is also used to form an organic layer.

The specific layer contains at least the binder resin and the m-phenylenediamine compound as a solvent or a dispersion medium.
The coating liquid contained in THF is applied by a normal coating method such as a spray coating method, a dipping method, or a flow coating method, and is formed by solidification or curing. 2.5x THF
It must be less than 10 ^-3 μ / mg. The amount of residual THF in the layer
If it exceeds 2.5 × 10 ^-3 μ / mg, it remains
The amount of excitation energy transferred from THF to the m-phenylenediamine-based compound is too large, and a large amount of the m-phenylenediamine-based compound undergoes a dimerization reaction or a decomposition reaction. Particularly, in a halftone image (gray image), the deteriorated portion becomes dark and unevenness or the like occurs, so that a practical image cannot be obtained.

As described above, the amount of THF remaining in the specific layer is 2.5 × 10
Various methods are conceivable for reducing the concentration to ^-3 μ / mg or less.However, the heat treatment at a temperature of 110 ° C. or more for 30 minutes or more allows the THF remaining in the specific layer to be vaporized and evaporated. According to the production method, the amount of residual THF can be reduced by simply heating, so that the electrophotographic photoreceptor of the present invention can be easily produced without requiring a large-scale apparatus or the like.

In the production method of the present invention, the heat treatment temperature of the specific layer is limited to 110 ° C. or more and the heat treatment time is limited to 30 minutes or more because the heat treatment temperature is less than 110 ° C. or the heat treatment time is less than 30 minutes. This is because the amount of residual THF cannot be sufficiently reduced.

The heat treatment temperature is preferably 130 ° C. or lower in order to prevent sublimation, decomposition, and the like of the functional components such as the charge generation material and the charge transport material contained in the specific layer.

The heat treatment under the above heating conditions may be performed on the specific layer that has already been solidified or cured, or may be performed simultaneously with the solidification or curing of the specific layer.

The specific layer preferably contains, in addition to the m-phenylenediamine-based compound, other conventionally known other charge transport materials (hereinafter, simply referred to as “other charge transport materials”). As other charge transporting materials contained in the specific layer together with the m-phenylenediamine compound,
For example, tetracyanoethylene; 2,4,7-trinitro-9-
Fluorenone compounds such as fluorenone; fluorene compounds such as 9-carbazolyliminofluorene; nitrated compounds such as dinitroanthracene; succinic anhydride; maleic anhydride; dibromomaleic anhydride; triphenylmethane compounds; -Di (4-dimethylaminophenyl)
Oxadiazole compounds such as -1,3,4-oxadiazole; styryl compounds such as 9- (4-diethylaminostyryl) anthracene; carbazole compounds such as poly-N-vinylcarbazole; 1-phenyl-3 Pyrazoline compounds such as-(p-dimethylaminophenyl) pyrazoline; 4,4 ', 4 "-tris (N, N-diphenylamino) triphenylamine, 3,3'-dimethyl-N, N, N', N'-tetrakis-4-methylphenyl (1,1'-biphenyl)
Amine derivatives such as -4,4'-diamine; 1,1-bis (4-
Conjugated unsaturated compounds such as diethylaminophenyl) -4,4-diphenyl-1,3-butadiene; hydrazone compounds such as 4- (N, N-diethylamino) benzaldehyde-N, N-diphenylhydrazone; indole compounds; oxazole Nitrogen-containing cyclic compounds such as a series compound, an isoxazole-based compound, a thiazole-based compound, a thiadiazole-based compound, an imidazole-based compound, a pyrazole-based compound, a pyrazoline-based compound, and a triazole-based compound; and a condensed polycyclic compound. Among the other charge transporting materials, a polymer material having photoconductivity such as poly-N-vinylcarbazole can be used also as a binder resin for the specific layer.

The mixing ratio of the other charge transporting material and the m-phenylenediamine compound in the specific layer is not particularly limited, but is in a range of 95: 5 to 25:75 by weight, particularly 80:20 to 5 by weight.
It is preferably within the range of 0:50. The mixing ratio of the other charge transporting material to the m-phenylenediamine compound is 95: 5.
Below, when the image forming process is repeated,
The effect of preventing a reduction in the amount of charge and a reduction in sensitivity becomes insufficient. Conversely, if the compounding ratio exceeds 25:75, the sensitivity of the photoconductor may become insufficient.

In the coating solution for the specific layer, another solvent or dispersion medium can be used in combination with THF as a solvent or dispersion medium.

Other solvents or dispersion media that can be used in combination with THF include, for example, aliphatic hydrocarbons such as n-hexane, octane, and cyclohexane; aromatic hydrocarbons such as benzene, xylene, and toluene; dichloromethane, carbon tetrachloride,
Halogenated hydrocarbons such as chlorobenzene and methylene chloride; alcohols such as methyl alcohol, ethyl alcohol, isopropyl alcohol, allyl alcohol, cyclopentanol, benzyl alcohol, furfuryl alcohol and diacetone alcohol; dimethyl ether, diethyl ether, ethylene glycol dimethyl ether , Ethylene glycol diethyl ether, ethers such as diethylene glycol dimethyl ether; acetone, methyl ethyl ketone, methyl isobutyl ketone,
Various solvents such as ketones such as cyclohexanone; esters such as ethyl acetate and methyl acetate; dimethylformamide; dimethyl sulfoxide, and the like are used alone or as a mixture of two or more. When preparing the coating liquid, a surfactant, a leveling agent, and the like may be used in combination in order to improve dispersibility, coatability, and the like.

The coating solution can be prepared by a conventional method, for example, using a mixer, a ball mill, a paint shaker, a sand mill, an attritor, an ultrasonic disperser, or the like.

In the electrophotographic photoreceptor of the present invention, portions other than the specific layer described above can be configured in the same manner as in the related art.

For example, among the above types of photosensitive layers, in the composite photosensitive layer, as a semiconductor material constituting a thin film used as a charge generation layer, for example, α-Se, α-As ₂ Se ₃ , α-
Amorphous chalcogenide amorphous silicon (α-Si) such as SeAsTe; The thin-film charge generation layer made of the semiconductor material can be formed on the surface of the conductive substrate by a known thin-film forming method such as a vacuum evaporation method and a glow discharge decomposition method.

Further, a single-layer type organic photosensitive layer (the specific layer), or used for the charge generation layer in the laminated organic photosensitive layer, as the organic or inorganic charge generation material, for example, the powder of the semiconductor material; ZnO, Group II-VI microcrystals such as CdS; pyrylium salts; azo compounds; bisazo compounds; α-type, β-type, γ
Phthalocyanine compounds such as aluminum phthalocyanine, copper phthalocyanine, metal-free phthalocyanine, titanyl phthalocyanine, etc. having a crystal form such as a type; anthanthrone compounds; indigo compounds; triphenylmethane compounds; slen compounds; toluidine compounds;
Pyrazoline compounds; quinacridone compounds; pyrrolopyrrole compounds. These charge generating materials can be used alone or in combination of two or more.

Of the above-mentioned types of photosensitive layers, the content of the charge generation material with respect to 100 parts by weight of the binder resin in the single-layer type organic photosensitive layer is in the range of 2 to 20 parts by weight, particularly 3 to 15 parts by weight. It is preferable that it is within the range. Further, the content of the other charge transporting material with respect to 100 parts by weight of the binder resin is 40 to 200.
It is preferably in the range of parts by weight, especially in the range of 50 to 100 parts by weight. The charge generation material content is less than 2 parts by weight,
Alternatively, if the content of the other charge transporting material is less than 40 parts by weight, the sensitivity of the photoconductor may be insufficient or the residual potential may be increased. On the other hand, when the content of the charge generating material exceeds 20 parts by weight, or when the content of the other charge transporting materials exceeds 200 parts by weight, the abrasion resistance of the photoconductor may be insufficient. .

The thickness of the single-layer type organic photosensitive layer is not particularly limited, but the same as that of the conventional single-layer type organic photosensitive layer, that is, 10
It is preferably in the range of 5050 μm, especially 15-25 μm.

Among the layers constituting the laminated organic photosensitive layer, the content of the charge generation material relative to 100 parts by weight of the binder resin in the organic charge generation layer is in the range of 5 to 500 parts by weight, particularly 10 to 2 parts by weight.
Preferably it is in the range of 50 parts by weight. When the content of the charge generation material is less than 5 parts by weight, the charge generation ability is too small,
If it exceeds 500 parts by weight, there is a possibility that the adhesion to the base material and other adjacent layers may be reduced.

The thickness of the charge generation layer is not particularly limited, but is 0.01 to
It is preferably within a range of 3 μm, especially 0.1 to 2 μm.

Among the layers constituting the laminated organic photosensitive layer or the composite photosensitive layer, in the charge transporting layer, the content of the other charge transporting material with respect to 100 parts by weight of the binder resin is in the range of 10 to 500 parts by weight, particularly It is preferably in the range of 25 to 200 parts by weight. If the content of the other charge transporting material is less than 10 parts by weight,
If the charge transporting ability is insufficient and exceeds 500 parts by weight, the mechanical strength of the charge transporting layer may be reduced.

The thickness of the charge transport layer is not particularly limited, but may be 2 to 10
It is preferably within a range of 0 μm, particularly 5 to 30 μm.

Further, the surface protective layer which can be formed on the outermost layer of each type of photosensitive layer contains the above-mentioned binder resin as a main component and, if necessary, adds a conductivity-imparting material or a benzoquinone-based ultraviolet absorbing material. The agent can be contained in an appropriate amount.

The thickness of the surface protective layer is 0.1 to 10 μm, particularly 2 to 5 μm.
It is preferably within the range of μm.

When an antioxidant is used in combination with the organic layer of the above-described types of photosensitive layers, the surface protective layer, and the like, deterioration due to oxidation of a functional component such as a charge transport material having a structure that is easily affected by oxidation. Can be prevented.

As the antioxidant, 2,6-di-tert-butyl-
p-cresol, triethylene glycol-bis [3-
(3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], pentane Erythrityl-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 2,2-thio-diethylenebis [3- (3,5-di-tert-butyl-4-) Hydroxyphenyl) propionate], 2,2-thiobis (4-
Methyl-6-tert-butylphenol), N, N'-hexamethylenebis (3,5-di-tert-butyl-4-hydroxy-hydrocinnamide), 1,3,5-trimethyl-2,
Examples include phenolic antioxidants such as 4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene.

The conductive substrate on which the photosensitive layer of each type is formed on the surface is formed into an appropriate shape, such as a sheet or a drum, corresponding to the mechanism and structure of the image forming apparatus in which the electrophotographic photosensitive member is incorporated. You.

The conductive base material may be entirely formed of a conductive material such as metal, or the base material itself may be formed of a structural material having no conductivity, and the surface may be provided with conductivity. Is also good.

The entirety of the conductive base is made of a conductive material, and the conductive material used in the former case includes alumite-treated or untreated aluminum, copper, tin,
Platinum, silver, vanadium, molybdenum, chromium, cadmium, titanium, nickel, palladium, indium, stainless steel, brass, and other metal materials are preferable, and in particular, aluminum anodized by alumite sulfate method and sealed with nickel acetate Is preferably used.

On the other hand, in the latter case of imparting conductivity to the surface of a substrate made of a structural material having no conductivity, the above-described metal or aluminum iodide may be applied to the surface of a synthetic resin substrate or a glass substrate. A structure in which a thin film made of a conductive material such as tin oxide, indium oxide, or the like is formed by a known film forming method such as a vacuum evaporation method or a wet plating method; A structure in which a film of a material or the like is laminated, a structure in which a substance imparting conductivity is injected into the surface of the synthetic resin base or the glass base, or the like can be employed.

The conductive substrate may be subjected to a surface treatment with a surface treatment agent such as a silane coupling agent or a titanium coupling agent, as necessary, to increase the adhesion to the photosensitive layer.

Of the photosensitive layers of each type described above, each of the organic layers and the surface protective layer other than the specific layer adjusts a coating solution for each layer containing each component described above, and these coating solutions are used for the specific layer. In order to form the above-described layer configuration together with the coating liquid, each layer may be sequentially coated on a conductive substrate and dried or cured to form a laminate.

In preparing the coating solution, one or two or more of the various solvents or dispersion media described above can be appropriately selected and used depending on the type of the binder resin or the like to be used.

<Example> Examination of heat treatment conditions 100 parts by weight of poly- (4,4'-cyclohexylidenediphenyl) carbonate (manufactured by Mitsubishi Gas Chemical Company, trade name: Z-200) as a binder resin, and 4 as a charge generation material , 10-Bromo-dibenzo [def, mno] chrysene 6,12-dione (2,7
5 parts by weight of dibromoanthanthrone) and 0.2 parts by weight of X-type metal-free phthalocyanine (manufactured by Dainippon Ink), 3,3'-dimethyl-N, N, N ', as a charge transport material
N'-tetrakis-4-methylphenyl (1,1'-biphenyl) -4,4'-diamine 70 parts by weight and N, N, N ', N'-
Tetrakis (3-tolyl) -1,3-phenylenediamine 3
0 parts by weight, 2,6-di-tert-butyl- as antioxidant
p-Cresol (manufactured by Kawaguchi Chemical Co., Ltd., trade name Antage BH)
T) 5 parts by weight and a predetermined amount of THF were mixed and dispersed with an ultrasonic disperser to prepare a single layer type photosensitive layer coating solution. This coating solution is applied on an aluminum tube having an outer diameter of 78 mm and a length of 344 mm, dried at room temperature, and then heat-treated at a temperature shown in Fig. 1 for 30 minutes in a dark place to obtain a single layer having a thickness of about 22 µm. A photosensitive layer was formed to produce a drum-type electrophotographic photosensitive member. Then, the remaining THF in the single-layer photosensitive layer of each electrophotographic photosensitive member
The amount was measured by pyrolysis gas chromatography. The results are shown in FIG.

From the results shown in FIG. 1, it was found that when the heating temperature was set to 110 ° C. or higher, the amount of residual tetrahydrofuran in the layer could be reduced to 2.5 × 10 ⁻³ μ / mg or less by a heat treatment for 30 minutes.

Examination of heat treatment conditions The above-mentioned coating solution for a single-layer type photosensitive layer was used for an outer diameter of 78 mm × length of 344 mm.
After coating on an aluminum base tube and drying at room temperature,
In a dark place, heat-treated at 110 ° C. for the time shown in FIG.
A single-layer photosensitive layer having a thickness of about 22 μm was formed to produce a drum-type electrophotographic photosensitive member. Then, the amount of residual THF in the single-layer type photoreceptor of each electrophotographic photoreceptor was measured by a pyrolysis gas chromatograph. The results are shown in FIG.

From the results shown in FIG. 2, when the heating time is set to 30 minutes or longer, the amount of residual THF in the layer is reduced to 2.5 × 10 ⁻³ μm by the heat treatment at 110 ° C.
/ mg or less was found to be possible.

Examination of heat treatment conditions The above single-layer photosensitive layer coating solution was coated with an outer diameter of 78 mm and a length of 34 so that the thickness of the photosensitive layer after the heat treatment had the thickness shown in FIG.
After coating on a 4 mm aluminum tube and drying at room temperature, it was heat-treated at 110 ° C. for 30 minutes in a dark place to form a single-layer photosensitive layer, thereby producing a drum-type electrophotographic photosensitive member.
Then, the residual in the single-layer type photosensitive layer of each electrophotographic photosensitive member
THF was measured by pyrolysis gas chromatography.
The results are shown in FIG.

According to the results shown in FIG. 3, in the range of 15 to 25 μm, which is the general thickness of the single-layer type photosensitive layer, heat treatment at 110 ° C. for 30 minutes is performed regardless of the thickness of the photosensitive layer. Residual THF in
It was found that the amount could be less than 2.5 × 10 ⁻³ μ / mg.

Examples 1 to 3 and Comparative Examples 1 and 2 The coating solution for a single-layer type photosensitive layer prepared in the examination of the heat treatment conditions was applied onto an aluminum tube having an outer diameter of 78 mm and a length of 344 mm, and dried at room temperature. Thereafter, in a dark place, heat treatment was performed under the heat treatment conditions shown in Table 1, and the amount of THF shown in the table remained in the layer. A drum-type electrophotographic photosensitive member having a single-layer photosensitive layer having a thickness of about 22 μm. Was prepared.

The following tests were performed on the electrophotographic photoreceptors produced in the above Examples and Comparative Examples.

The initial surface potential measuring each potential photosensitive member, an electrostatic copying test apparatus (Gen-Tech Co., Gen-Tech Cynthia 30M) was charged to the measured positively charged so the surface potential V ₁ sp (V) of the surface did.

Measurement of half-reduction exposure amount and residual potential Each electrophotographic photosensitive member in the charged state is exposed using a halogen lamp as an exposure light source of the electrostatic copying test apparatus, and the surface potential V ₁ sp (V) is reduced to half. The half-exposure amount E1 / 2 (μJ / cm ² ) was calculated.

Further, the surface potential 0.19 seconds after the start of the exposure was measured as a residual potential V ₁ rp (V).

Surface potential change value and residual potential change value measurement after ultraviolet irradiation At two points on each electrophotographic photoreceptor, surface potentials V _1a sp, V _1b sp, and
After measuring the residual potentials V _1a rp and V _1b rp [or more, unit (V)], the electrophotographic photosensitive member was preheated to 60 ° C. in a dark place.
Store 20 minutes, then, while kept at 60 ° C., it was masked by the light shielding bodies V _1b side of the point of the two places, on the surface of the electrophotographic photosensitive member, a white fluorescent lamp (trade name National High Using a light FL, 15 W), 1500 lux of white light containing ultraviolet light was exposed for 20 minutes. Then, the exposed electrophotographic photoreceptor is left in a dark place at room temperature for 30 minutes, cooled, and then loaded into an electrostatic copying test apparatus (Gentec Cynthia 30M, manufactured by Gentec Corporation), and the surface thereof is correctly adjusted After charging, the two surface potentials V _2a sp (exposure side) and V _2b sp
(Light blocking side), residual potential V _2a rp (exposure side), V _2b
rp (light shielding side) [the unit (V)] was measured.

Based on the above measured values, a surface potential displacement value ΔV _1-2 sp (V) after shielding from ultraviolet rays is calculated using the following equation (a), and is calculated using the following equation (b). Residual potential change value ΔV
_1-2 rp (V) was calculated.

ΔVs.p. = (V _2a sp−V _1a sp) − (V _2b sp−V _1b sp)... (A) ΔVr.p. = (V _2a rp−V _1a rp) − (V _2b rp−V _1b rp) ... (b) Practical test Each electrophotographic photoreceptor after ultraviolet irradiation was loaded into a copying machine (Mita Kogyo Co., Ltd., DC-1655 model), and a halftone original was copied to reduce unevenness in image density. Observation was made by visual observation, and those without density unevenness were evaluated as ○, and those with density unevenness were evaluated as x.

 The results are shown in the following table.

From the results in the above table, the amount of residual THF in the single-layer type photosensitive layer was 2.5%.
× 10 ⁻³ μm / mg or less, the electrophotographic photoreceptors of Examples 1 to 3 each had an amount of change in surface potential due to ultraviolet irradiation compared to Comparative Examples 1 and 2 in which the amount of residual THF exceeded the above value. Is 20 V or less, and the amount of change in the residual potential is as small as 20 V or less. This indicates that the electrophotographic photoreceptors of Examples 1 to 3 were hardly deteriorated by ultraviolet rays.

<Effects of the Invention> The electrophotographic photoreceptor of the present invention is configured as described above, and is excellent in an action of preventing a decrease in charge amount and a decrease in sensitivity when an image forming process is repeatedly performed. The above m- residue remaining in the layer containing the system compound
TH promotes UV degradation of phenylenediamine compounds
Since the amount of F is set to 2.5 × 10 ⁻³ μ / mg or less in advance, particularly when the photoconductor is heated, such as during operation of an image forming apparatus, ultraviolet light such as a fluorescent lamp, a xenon lamp, or sunlight. , The sensitivity is unlikely to decrease even when irradiated with light containing.

Further, according to the method of manufacturing an electrophotographic photoreceptor of the present invention, the amount of residual THF in the layer can be reduced by simply heating the above layer, so that a large-scale apparatus or the like is not required, and the present invention can be easily performed. An electrophotographic photoreceptor can be manufactured.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the heat treatment temperature and the amount of residual THF in the single-layer type photosensitive layer, FIG. 2 is a graph showing the relationship between the heat treatment time and the amount of residual THF in the single-layer type photosensitive layer, and FIG. 4 is a graph showing the relationship between the thickness of a single-layer photosensitive layer and the amount of residual THF after heat treatment.

Claims (2)

(57) [Claims] An electrophotographic photoreceptor comprising a layer formed by applying a coating solution containing a binder resin, an m-phenylenediamine compound as a charge transport material, and tetrahydrofuran. Wherein the residual amount of tetrahydrofuran is previously 2.5 × 10 ⁻³ μ / mg or less. 2. A layer formed by applying a coating solution containing a binder resin, an m-phenylenediamine compound as a charge transporting material, and tetrahydrofuran is heat-treated at a temperature of 110 ° C. or more for 30 minutes or more. Wherein the amount of residual tetrahydrofuran in the layer is adjusted to 2.5 × 10 ⁻³ μ / mg or less.