JP5608458B2 - Electrophotographic photoreceptor and image forming apparatus having the same - Google Patents

Description

The present invention relates to an electrophotographic photosensitive member and an image forming apparatus including the same.
Specifically, the present invention relates to an electrophotographic photosensitive material in which the intermediate layer contains a blocked isocyanate compound and an active hydrogen-containing group capable of reacting with an isocyanate group, and the photosensitive layer contains a specific triphenylamine compound as a charge transport material. About the body.
More specifically, the present invention relates to an intermediate layer prepared from a coating solution for forming an intermediate layer of an electrophotographic photosensitive member using an aqueous medium as a solvent, wherein the intermediate layer contains an active hydrogen-containing group capable of reacting with a blocked isocyanate compound and an isocyanate group. The present invention relates to a photosensitive layer containing a triphenylamine compound having a specific triphenylamine structure having a high charge mobility as a charge transport material, and an image forming apparatus including the same.

An electrophotographic photosensitive member (hereinafter also referred to as a “photosensitive member”) used in an electrophotographic image forming apparatus (also referred to as an “electrophotographic device”) that is frequently used in digital multi-function peripherals, printers, and the like is mounted on a conductive support. And a photosensitive layer containing a photoconductive material.
Conventionally, inorganic photoconductive materials such as selenium and organic photoconductive materials have been used as photoconductive materials.
Although organic photoconductive materials are slightly inferior to inorganic photoconductive materials in terms of sensitivity, durability, and environmental stability, they are inorganic photoconductive in terms of toxicity, manufacturing cost, and freedom of material design. In recent years, it is widely used for electrophotographic photoreceptors.

In addition, the structure of the photoreceptor has changed from a single layer type in which a charge generation material and a charge transport material are dispersed in a binder resin to a functional separation type in which the charge generation layer and the charge transport layer are separated. Performance has also improved.
For example, there has been proposed a technique for realizing a reduction in size of an image forming apparatus and an increase in image forming speed by using a photoconductor provided with a charge transport layer having a specific charge mobility (Japanese Patent Laid-Open No. 8-62862). No. (Patent Document 1)).

Such a function-separated type photoconductor has an advantage that the charge generation material and the charge transport material can be selected separately, so that the material selection range of the charge generation material and the charge transport material is wide. Therefore, a high-performance photoreceptor can be provided by combining materials so that electrophotographic characteristics such as charging characteristics, sensitivity, residual potential characteristics, repetition characteristics, and printing durability are optimized.
Further, since the photosensitive layer can be formed by coating, it is possible to provide an inexpensive photoconductor with extremely high productivity.
In addition, the photosensitive wavelength range of the photosensitive member can be freely controlled by appropriately selecting the charge generating material.

Because of such many advantages, a function-separated type organic photoconductor has been used in most commonly used copying machines and printers.
In recent years, image forming apparatuses such as a copying machine, a printer, a facsimile machine, and an electrophotographic plate making machine are required to be downsized, increase the image forming speed, and extend the life. In such an image forming apparatus, a photoreceptor having a photosensitive layer provided on the outer peripheral surface of a cylindrical or columnar conductive support is generally used. For the downsizing of the image forming apparatus, the photoreceptor is used. It is necessary to reduce the diameter. However, since the distance from the exposure position to the development position is short for a photoconductor having a small diameter, performing an electrophotographic process at a high speed in order to increase the image formation speed shortens the time from exposure to development. The following problems arise.

  For example, if a photoconductor with low responsiveness, that is, a photoconductor with a slow decay rate of the surface potential after exposure is used, the next image is developed in a state where the surface potential of the portion to be erased by exposure is not sufficiently attenuated. Will be. As a result, in the case of regular development, a phenomenon called background smearing occurs in which toner adheres to the white portion of the image, and in the case of reversal development, the image density decreases.

Therefore, in order to achieve both a reduction in the size of the image forming apparatus and an increase in the image forming speed, improvement in the responsiveness of the photoreceptor is required. Further, in order to extend the life of the image forming apparatus, it is required to extend the life of the photoreceptor.
In order to meet the above requirements, the present inventors have devised the use of a triphenylamine compound having a specific structure with extremely high mobility and strong printing durability for the charge transport layer.

On the other hand, in recent years, a configuration in which an intermediate layer (undercoat layer) is laminated between a conductive support, a charge generation layer, and a charge transport layer has become mainstream.
The intermediate layer can be used to improve the adhesion of the photosensitive layer by coating the defects on the conductive support, improve the film formability (coatability), prevent unnecessary charge injection from the conductive support, and improve the chargeability associated therewith. It has a function.

An intermediate | middle layer is divided roughly into what consists of resin independent, and what consists of resin containing the pigment.
Examples of the resin used for the intermediate layer include water-soluble resins such as polyvinyl alcohol and casein; alcohol-soluble resins such as copolymer nylon resins; three-dimensional such as polyurethane, melamine resin, phenol resin, alkyd resin, epoxy resin, and siloxane resin. Examples thereof include a thermosetting resin that forms a network structure.

However, since water-soluble resins and alcohol-soluble resins are rich in moisture adsorbability and affinity, the physical properties of these resins are very dependent on the environment, and there is a problem that the characteristics of the photoreceptor change depending on humidity. is there.
Especially at high humidity, the intermediate layer absorbs a large amount of moisture, so the characteristics of the photoconductor change greatly when the photoconductor is used repeatedly at high and high humidity and low and low humidity, resulting in abnormal images such as black spots and reduced density. Is caused.

Therefore, a thermosetting resin that forms a three-dimensional network structure excellent in solvent resistance and environmental stability was adopted.
However, for example, a melamine resin disclosed in Japanese Patent No. 3657138 (Patent Document 2); for example, a phenol resin and a methoxymethylated nylon resin disclosed in Japanese Patent No. 2707341 (Patent Document 3); It is said to be one of the causative substances of sick house syndrome during resin production, and a large amount of formaldehyde, which is currently a target substance of the Air Pollution Control Law, is used. Therefore, there is a problem that unreacted substances during production are occluded in the resin, and formaldehyde is generated in the process of thermal crosslinking after the formation of the intermediate layer of the photoreceptor. In order to prevent the release of the generated formaldehyde into the atmosphere, a recovery facility is necessary, and it is obviously expensive to introduce the facility.

In addition, for example, in the urethane resin disclosed in Japanese Patent No. 2790380 (Patent Document 4), an active hydrogen-containing group such as a polyol compound and an isocyanate group of an isocyanate compound that is a curing agent have a three-dimensional network crosslinking reaction. Since a cured film is formed by this, formaldehyde is not generated.
However, since the reactivity of the isocyanate group is very high, there is a problem that the pot life of the coating liquid using these is very short.

Therefore, a method using a blocked isocyanate compound in which an isocyanate group is protected with a blocking agent such as oxime has been reported, and the pot life of a coating solution using an organic solvent has been considerably improved (for example, JP-A-2005-115351). (Patent Document 5), JP-A-2006-285077 (Patent Document 6)).
In addition, the intermediate layer and the photosensitive layer are coated with a coating solution containing water and alcohol as the main components, and both are thermally cured to reduce the total environmental impact and improve the printing durability of the photoreceptor. (For example, JP 2002-6516 A (Patent Document 7)).

However, although the printing durability is improved by thermosetting the photosensitive layer, at the low temperature, the charge transport ability is lowered, the residual potential is increased, and the sensitivity is lowered, which eventually affects the image density.
As described above, an electrophotographic photoreceptor using an intermediate layer using an alcohol-soluble resin such as a copolymer nylon resin and a triphenylamine-based compound having a specific structure for a charge transport layer is excellent in responsiveness and printing durability. Long life was achieved.

JP-A-8-62862 Japanese Patent No. 3657138 Japanese Patent No. 2707341 Japanese Patent No. 2790380 JP-A-2005-115351 JP 2006-285077 A JP 2002-6516 A

However, in recent years, fluctuations in image density have become a problem when used in areas where air conditioning equipment is not sufficient due to the expansion of use areas, and during use in the time when air conditioning is not sufficient in the morning due to expansion of usage time. .
This problem is caused by the large dependence of the electrophotographic photosensitive member on temperature and humidity, particularly in the case where the sensitivity is significantly reduced at low temperatures and low humidity, and sometimes it cannot be solved by adjusting the development process.

As a result of further examination, the moisture in the resin used for the intermediate layer is desorbed at low humidity and the intermediate layer has high resistance, while moisture is adsorbed and low resistance at normal to high humidity. It was found that the chargeability of the body changed significantly and the image density changed.
As a countermeasure against this, there is a method of increasing the ratio of the resin binder resin used for the charge transport layer on the surface side, thereby blocking the permeation of moisture and suppressing the change in the amount of moisture in the intermediate layer. However, increasing the resin binder resin means lowering the concentration of the charge transport agent, particularly at low temperatures, the charge transport ability is lowered, the residual potential is increased, the sensitivity is lowered, and eventually the image density is affected. It does not lead to a solution.
These problems can be almost solved by the above-mentioned thermosetting intermediate layer. However, due to the recent trend of strengthening regulations on environmental conservation measures, the above-mentioned thermosetting intermediate layer that causes environmental pollution during production can be used in practice. It has become difficult.

A compound having a triarylamine compound having a specific structure as a charge transport material has a feature that it has a high charge mobility even in a low humidity environment, but on the other hand, it is dependent on humidity and is sensitive to the environment. There is a drawback that it is easy to cause fluctuations. Such a variation in sensitivity may appear as an image defect such as dirt on an actual image.
At the same time, it aims to reduce environmental impact and improve production stability in the photoreceptor manufacturing process.

That is, the present invention uses an aqueous medium having the smallest environmental load as a solvent, and has excellent stability over time of liquid physical properties in production, small change in volume resistance due to humidity, small change in sensitivity due to environmental changes, and stability. By using a compound having a specific triphenylamine structure as a charge transport material having a high charge mobility in the intermediate layer coated from the coating solution excellent in the above, a reduction in environmental load in the photoreceptor manufacturing process, The goal is to improve production stability.
Furthermore, the present invention has little sensitivity fluctuation due to environment dependence, exhibits high responsiveness even in a low temperature and low humidity environment, is small in size, has a high image forming speed, and can provide a high quality image even in an environment such as low temperature and low humidity. . In addition, by using a compound having a triphenylamine structure having high printing durability, the durability of the drum is remarkably improved, and an electrophotographic photosensitive member having high reliability over a long period of time and an image forming apparatus using the same are provided. Let it be an issue.

In the present invention, a combination of a blocked isocyanate compound, a resin having an active hydrogen-containing group capable of reacting with an isocyanate group in the blocked isocyanate compound, and a triphenylamine structure having a specific structure provides high sensitivity and high moisture resistance, that is, an environment. The above-mentioned problems are solved by a photoconductor that has a very low variation in water concentration even if it fluctuates.
In order to realize an intermediate layer coating solution using an aqueous medium that does not generate a volatile organic compound (VOC) and does not cause a fire as described above, the present inventors have prepared a blocked isocyanate compound, an isocyanate group, An intermediate layer formed by a coating solution for forming an intermediate layer in which an active hydrogen-containing group-reactive resin is dissolved or suspended in an aqueous medium has been devised.

  Furthermore, by combining a photosensitive layer containing a triphenylamine compound having a specific structure as a charge transport material with the intermediate layer, the environmental load in the photoreceptor manufacturing process is reduced, the production stability is high, and the environment Sensitivity fluctuation due to dependence is small, high responsiveness is exhibited even in a low-temperature and low-humidity environment, and high-quality images can be provided in various environments such as a compact, high-speed image formation speed and a low-temperature and low-humidity environment. In addition, a photoconductor having a triphenylamine compound having a specific structure is superior in mechanical durability, so that it is high without increasing the binder resin content at the expense of electrical characteristics as in the case of using a normal charge transport material. It has become possible to maintain the responsiveness and to devise a highly reliable electrophotographic photosensitive member and to devise an image forming apparatus using the same.

Thus, according to the present invention, an intermediate layer; a charge generating layer containing a charge generating material and a charge transporting layer containing a charge transporting material are laminated in this order on the conductive support, or a reverse layered photosensitive layer. A layer or a single-layer type photosensitive layer containing a charge generating material and a charge transport material;
The intermediate layer includes at least a blocked isocyanate compound and a binder resin having an active hydrogen-containing group capable of reacting with an isocyanate group,

The photosensitive layer has the following general formula (I) as a charge transport material:

Wherein R is a 2,2-diphenylethenyl group optionally substituted by a C ₁ -C ₆ alkyl or C ₁ -C ₆ alkyl group, and R ₁ -R ₇ are independently of each other halogen atom is any one of substituents selected from the group consisting of C ₁ -C ₆ alkyl groups and C ₆ -C ₁₂ aryl group, a to f represents an integer of 0 to 3, g is 0 It is an integer of ~ 2)
An electrophotographic photoreceptor characterized by containing a triphenylamine compound represented by the formula:

  According to the invention, the intermediate layer comprises a coating solution for forming an intermediate layer in which at least a blocked isocyanate compound and a binder resin having an active hydrogen-containing group capable of reacting with an isocyanate group are dissolved or dispersed in an aqueous medium. A method for producing the electrophotographic photoreceptor obtained by applying and thermosetting is provided.

  Further, according to the present invention, the electrophotographic photosensitive member, the charging means for charging the electrophotographic photosensitive member, and the charged electrophotographic photosensitive member are exposed to form an electrostatic latent image. An exposure unit; a developing unit that develops the electrostatic latent image to form a toner image; a transfer unit that transfers the toner image onto a recording material; and the transferred toner image is fixed onto the recording material. The image forming apparatus includes at least a fixing unit that forms an image, a cleaning unit that removes and collects toner remaining on the electrophotographic photosensitive member, and a neutralizing unit that neutralizes surface charges remaining on the electrophotographic photosensitive member. An image forming apparatus is provided.

  The present invention uses an aqueous medium having the smallest environmental load as a solvent, and has excellent stability over time of liquid physical properties even in production, changes in volume resistance due to humidity are small, changes in sensitivity due to environmental changes are small, and stability is improved. An intermediate layer obtained from an excellent coating solution is combined with a photosensitive layer containing a charge transport material having a specific triphenylamine structure. Therefore, according to the present invention, the environmental load is smaller, the production stability is higher, the sensitivity fluctuation due to the environment is less, the responsiveness in a low-temperature and low-humidity environment is higher, and the image formation is smaller than the conventional photoconductor manufacturing process. A high-quality image can be obtained even in an environment such as high speed and low temperature and low humidity, and the printing durability of the photoconductor can be remarkably improved, thereby providing an electrophotographic photoconductor that has high reliability over a long period of time.

Further, by using an aqueous medium instead of an organic solvent as a solvent for the coating solution, air pollution due to VOC in the manufacturing process can be eliminated. In addition, since no CO ₂ emissions as petroleum solvent which has been conventionally used, which contributes to the prevention of global warming. Furthermore, since there is no risk of fire, the manufacturing system can be simplified and the manufacturing cost can be reduced.
In addition, when the solvent is an aqueous medium, a binder resin having a high affinity for water can be used, but in this case, the moisture resistance of the electrophotographic photosensitive member may be lowered. However, the above moisture resistance property is obtained by applying a coating solution for forming an intermediate layer in which a binder resin having an active hydrogen-containing group capable of reacting with an isocyanate group and a blocked isocyanate compound is dissolved or dispersed on a conductive support. By subjecting this to a thermosetting reaction, by reacting the above active hydrogen-containing group and an isocyanate group, the hydrophilic functional group is reduced, and the coating film is densified as a cured film, whereby the moisture resistance of the photoreceptor is increased. Can be improved, and excellent environmental stability can be obtained.

Furthermore, according to the present invention, an isocyanate group that easily reacts with water usually uses a blocked isocyanate compound in which the isocyanate group is protected, so that it is equal to or higher than a conventional organic solvent-based coating solution even in an aqueous medium. It has been found that pot life can also be realized.
Further, since the photosensitive layer contains a triphenylamine compound having a high charge mobility and excellent printing durability represented by the general formula (I), it exhibits high responsiveness even in a low-temperature and low-humidity environment, and printing durability. An electrophotographic photoreceptor excellent in the above can be obtained.
Therefore, even when the electrophotographic photosensitive member is miniaturized and used in a high-speed electrophotographic process, high-quality images can be provided over a long period of time in various environments such as a low temperature and low humidity environment. By using such an electrophotographic photosensitive member, it is possible to provide a stable and high-quality image even in various environments such as a small size, a high image forming speed, and a low temperature and low humidity environment. A high image forming apparatus can be realized.

In addition, the electrophotographic photosensitive member using the triphenylamine compound represented by the general formula (I) is excellent in abrasion and can ensure stable image characteristics over a long period of time.
Further, since the triphenylamine compound represented by the general formula (I) can be easily produced, the cost of the electrophotographic photosensitive member can be reduced.
Furthermore, by using a resin having two or more active hydrogen-containing groups capable of reacting with an isocyanate group such as a hydroxyl group or an amide group, the resin can be easily thermoset with an isocyanate compound.

When the isocyanate group is present in the blocked isocyanate compound at a molar ratio of 0.5 to 1.5 with respect to the active hydrogen-containing group in the resin, a dense cured film can be formed, Excellent environmental characteristics can be realized.
Furthermore, when the blocked isocyanate compound has a specific blocked structure, a photoreceptor having better properties can be provided.

Still further, when the binder resin is selected from specific resins, it is possible to provide a photoconductor having better properties.
Further, when the coating liquid for forming an intermediate layer contains inorganic oxide fine particles, when the inorganic oxide fine particles are titanium oxide or zinc oxide, when having a specific average primary particle size, the electric resistance of the intermediate layer is reduced. Since it can be easily controlled, it is possible to prevent image defects such as repetitive characteristics and black spots of the electrophotographic photosensitive member.

Moreover, when the coating liquid for forming an intermediate layer further contains an antifoaming agent, an intermediate layer having excellent properties can be provided.
According to the image forming apparatus provided with the electrophotographic photosensitive member, it is possible to improve repetitive characteristics and environmental stability.

FIG. 3 is a schematic cross-sectional view illustrating a configuration of a main part of the photoreceptor of the present invention. FIG. 3 is a schematic cross-sectional view illustrating a configuration of a main part of the photoreceptor of the present invention. FIG. 3 is a schematic cross-sectional view illustrating a configuration of a main part of the photoreceptor of the present invention. 1 is a schematic side view illustrating a configuration of an image forming apparatus of the present invention.

The intermediate layer constituting the electrophotographic photoreceptor of the present invention is obtained by dissolving or dispersing a blocked isocyanate compound, that is, a binder resin having at least one active hydrogen-containing group capable of reacting with an isocyanate group in the blocked isocyanate compound in an aqueous medium. It is obtained by applying and heat-curing the intermediate layer forming coating solution.
The binder resin preferably has two or more active hydrogen-containing groups.

The term “block isocyanate compound” in the present invention means an organic isocyanate compound that can be dissolved or dispersed in water, and further means a compound in which the isocyanate group of the compound is protected with a blocking agent such as oxime. This blocked isocyanate compound reacts with the removal of the blocking agent due to the progress of an addition reaction with a hydroxyl group or amide group, which is an active hydrogen-containing group capable of reacting with the isocyanate group contained in the binder resin, to form a crosslinked structure. To do.
That is, the blocked isocyanate compound in the present invention serves as a crosslinking agent for the binder resin.

  The organic isocyanate compound used in the present invention is dissolved or self-emulsified by modifying an organic polyisocyanate having a plurality of isocyanate groups in one molecule with various hydrophilic groups such as polyethylene oxide, carboxyl groups or sulfonic acid groups. Or a compound that is forcibly emulsified with a surfactant or the like so as to be dispersible in water.

  Examples of the organic polyisocyanate include phenylene diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, naphthylene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, hydrogenated diphenylmethane diisocyanate, polymethylene polyphenyl polyisocyanate, hydrogenated toluene. And diisocyanate, tetramethylene xylylene diisocyanate; and biuret, uretdione, carbodiimide, isocyanurate, and uretonimine modifications of the isocyanate.

These organic polyisocyanates can be used alone or in combination of two or more.
Among these organic polyisocyanates, aliphatic diisocyanates such as hexamethylene diisocyanate and isophorone diisocyanate are easy to have an affinity for water, so that they can be easily dissolved and dispersed in water, and the crosslinking density can be easily increased. Therefore, it is particularly preferable.

In addition, various prepolymers derived from organic polyisocyanates, and further as blocking agents for blocking isocyanate groups in these organic polyisocyanates include active methylene compounds such as ethyl acetate and acetylacetone; butyl mercaptan , Mercaptan compounds such as dodecyl mercaptan, acid amide compounds such as acetanilide and acetic acid amide; lactam compounds such as ε-caprolactam, δ-valerolactam and γ-butyrolactam; acid imides such as succinimide and maleic acid imide Compounds: Imidazole compounds such as imidazole and 2-methylimidazole; Urea compounds such as urea, thiourea and ethyleneurea; Formamide oxime, acetoaldoxime, acetone oxime, methyl ethyl keto Shim, methyl isobutyl ketoxime, oxime compounds such as cyclohexanone oxime; diphenylaniline, aniline, carbazole, ethyleneimine, include amine compounds such as polyethyleneimine.
These blocking agents can be used alone or in combination of two or more.
Among these blocking agents, oxime compounds such as methyl ethyl ketoxime and lactam compounds such as ε-caprolactam are particularly preferable from the viewpoint of versatility, ease of production, and workability.

Also, since the isocyanate group easily reacts with water, it is preferable to use a blocking agent having a dissociation temperature of 110 ° C. or higher so that the blocking agent dissociates after the water in the coating film volatilizes.
Therefore, the block isocyanate compound preferably has a structure in which hexamethylene diisocyanate or isophorone diisocyanate is blocked with an oxime or lactam blocking agent.

As the blocked isocyanate compound, for example,
Manufactured by Sumika Bayer Urethane Co., Ltd., product names: Bihijoule BL5140, BL5235 and VPLS2310;
Product name: Takenate WB-700, WB-820 and WB-920, manufactured by Mitsui Chemicals Polyurethane Co., Ltd .;
Product name: BWD-102, manufactured by Nippon Polyurethane Industry Co., Ltd.
Asahi Kasei Chemicals Corporation, developed product name: X1238, X1248 and X1258
Etc.

The active hydrogen-containing group in the binder resin having two or more active hydrogen-containing groups that can react with the isocyanate group in the blocked isocyanate compound is preferably a hydroxyl group or an amide group that can react with the isocyanate group in a high yield.
That is, it has two or more hydroxyl groups or amide groups to form a crosslinked structure with the blocked isocyanate as a curing agent (if it has only one functional group, it does not have a crosslinked structure but has a high molecular weight). Polyol resins and polyamide resins are preferred. In addition, by controlling the structure of these polyol resins and polyamide resins, it can be dispersed and dissolved in water satisfactorily. Furthermore, these resins have high adhesiveness to the substrate, and the substrate and the substrate when it is used as a photoreceptor. Image defects due to poor contact can also be effectively prevented.

Examples of the binder resin include:
Product name: AQD-457 and AQD-473, Asahi Glass Co., Ltd., product name: Exenol 420 and 720, Sanyo Chemical Industries, Ltd., product name: Sannix GP-400, GP-700 And polyether polyol resins (polyol compound resins) such as SP-750;
Hitachi Chemical Co., Ltd., product name: Phthalkid W2343, DIC Corporation, product name: Watersol S-118, CD-520 and BCD-3040, Harima Kasei Co., Ltd., product name: Hallidip WH-1188, etc. Polyester polyol resins of

Product name: Burnock WE-300, WE-304 and WE-306, manufactured by Asia Industry Co., Ltd., product name: WAP-473-FD and WAP-548 (polyol compound series) resin);
Manufactured by Kuraray Co., Ltd., product name: polyvinyl alcohol resins such as modified polyvinyl alcohols such as Kuraray Poval PVA-203 and PVA-205;

Manufactured by Sekisui Chemical Co., Ltd., product name: polyvinyl acetal resins such as ESREC K KW-1 and KW-3;
Manufactured by Shin-Etsu Chemical Co., Ltd., product name: cellulose such as water-soluble cellulose ethers such as Metroles 65SH-50 and 65SH-400;
Made by Nagase ChemteX Corporation, product name: Water-soluble nylon (polyamide compound resin) such as Toresin FS-350 and FS-500
Etc.

The isocyanate group H of the blocked isocyanate compound is preferably used in a molar ratio (H / B) of 0.5 to 1.5 with respect to the active hydrogen-containing group B of the binder resin, and 0.5 to 1.2 is used. More preferred is 0.6 to 1.1.
When this molar ratio (H / B) is less than 0.5 or exceeds 1.5, many unreacted active hydrogen-containing groups remain, the crosslinking density is lowered, and the formed intermediate layer is In some cases, the environmental stability of the photoconductor may decrease.

The intermediate layer forming coating solution of the present invention may further contain inorganic oxide fine particles.
The inorganic oxide fine particles adjust the volume resistance value of the intermediate layer when it is used as a photoconductor to prevent the injection of carriers from the conductive support to the photoconductive layer, and to improve the electric characteristics of the photoconductor in various environments. It has a function to maintain.

Examples of the inorganic oxide fine particles include fine particles such as titanium oxide, aluminum oxide, tin oxide, zinc oxide, antimony oxide, silicon oxide, indium oxide, zirconium oxide, magnesium oxide, and barium sulfate. Among these, fine particles of titanium oxide, zinc oxide and aluminum oxide are preferable in terms of dielectric constant, and fine particles of titanium oxide and zinc oxide are particularly preferable.
The shape of the inorganic oxide fine particles may be any of dendritic, acicular and granular.
The number average primary particle size of the inorganic oxide fine particles is preferably about 20 to 500 nm.

Examples of inorganic oxide fine particles include:
Ishihara Sangyo Co., Ltd., product name: TTO-55D (shape: granular, average primary particle size: 30-50 nm), TTO-D-1 (shape: dendritic, average primary particle size: minor axis 40-70 nm, long Axis 200-300 nm), ST-21 (shape: granular, average primary particle size (measured by X-ray) 70 nm), PT-401M (shape: granular, average primary particle size: 70 nm) and CR-EL (shape: granular) Average primary particle size: 250 nm),
Product name: GTR100 (shape: granular, average primary particle size: 260 nm), manufactured by Sakai Chemical Industry Co., Ltd.

Product name: MT-500SAS (shape: granular, average primary particle size: 35 nm) and JR-603 (shape: granular, average primary particle size: 280 nm)
Fine particles of titanium oxide such as
Ishihara Sangyo Co., Ltd., product name: FZO-50 (shape: granular, average primary particle size: 21 nm),
Product name: FINEX30 (shape: granular, average primary particle size: 35 nm), STR-60 (shape: needle shape), manufactured by Sakai Chemical Industry Co., Ltd.
Product name: MZ-300 (shape: granular, average primary particle size: 30-40 nm)
Examples thereof include fine particles of zinc oxide such as product name: F-2 (shape: rod shape, average primary particle size: 65 nm) manufactured by Hakusui Tech Co., Ltd.

The inorganic oxide fine particles (P) are preferably in a weight ratio (P / R) in the range of 5/5 to 9/1 with respect to the crosslinked resin (total of blocked isocyanate compound and resin: R).
When this weight ratio (P / R) is less than 5/5, the characteristics of the intermediate layer depend on the characteristics of the crosslinked resin, and the characteristics of the photoconductor may change greatly particularly when the temperature and humidity are changed and used repeatedly. On the other hand, when the weight ratio (P / R) exceeds 9/1, the dispersibility of the inorganic oxide fine particles is lowered, and the possibility of forming an aggregate is increased, and the adhesiveness to the conductive support is lowered. As a result, image defects such as black spots may occur.

The intermediate layer forming coating solution of the present invention may further contain an antifoaming agent.
The antifoaming agent is intended to suppress foam by adding a very small amount to the intermediate layer forming coating solution.
When an aqueous medium is used as a solvent as in the coating solution for forming an intermediate layer of the present invention, and particularly when a water-soluble resin is added, foaming is caused by dispersion or stirring during preparation to reduce dispersion or stirring efficiency. In addition, it may foam at the time of application and cause coating film defects. Antifoaming agents suppress these problems.

Examples of the antifoaming agent include a silicone system, a surfactant system, a polyether system, a higher alcohol system, an emulsion system, and an oil compound system. Among these, an oil compound system containing silica powder having a strong foam breaking property is particularly preferable.
As an antifoamer, for example, product name: SN deformer 444, 470, 485, PC (polyether type), SN deformer 1311, 1316 (silicone type), SN deformer-777, 328, 480, manufactured by San Nopco Co., Ltd. H-2 (oil compound system), manufactured by Nissho Sangyo Co., Ltd., product name: TSA750 (oil compound system), TSA770 (emulsion system), manufactured by Toray Dow Corning Co., Ltd .: product name: DK Q1-1247 Examples include silicone emulsions.
The defoaming agent is preferably 0.0005 to 0.05 parts by weight with respect to 1 part by weight of the cross-linked resin (total of blocked isocyanate compound and resin: R).
When the defoaming agent is 0.05 parts by weight or more, the electrical characteristics of the photoreceptor may be deteriorated, and when it is less than 0.0005 parts by weight, an effective foam breaking effect may not be obtained.

The coating solution for forming an intermediate layer of the present invention may contain additives such as a viscoelasticity adjusting agent, a preservative, and a curing catalyst as long as the effects of the present invention are not impaired.
As the viscoelasticity modifier, for example, manufactured by San Nopco Corporation, product names: SN thickener 601, A816 (polyether type), SN thickener 607 (urethane modified polyether type), SN thickener 617 (modified polyacrylic acid type), A product name: Water-soluble cellulose ether such as Metroze 65SH-4000 manufactured by Shin-Etsu Chemical Co., Ltd. can be mentioned.

As an antiseptic | preservative, the organic nitrogen sulfur type compound like the product made from San Nopco Co., Ltd. product name: Nopcoside SN-135W etc. are mentioned, for example.
Examples of the curing catalyst include amine compounds such as triethylamine, diethylethanolamine, and hexamethylenediamine; and organotin compounds such as dibutyltin dilaurate and dioctyltin dilaurate.

Moreover, the coating liquid for intermediate | middle layer formation may contain the electron transport substance in order to adjust electroconductivity.
Examples of the electron transport material include perylene dyes, quinones such as diphenoquinone and naphthoquinone derivatives, cyano compounds such as tetracyanoethylene and terephthalmalondinitrile, aldehydes such as 4-nitrobenzaldehyde, anthraquinone and alizarin. Anthraquinones are mentioned.

The coating solution for forming an intermediate layer can be prepared by dissolving or dispersing a blocked isocyanate compound, a binder resin having at least one active hydrogen-containing group capable of reacting with an isocyanate group, and an optional additive in an aqueous medium.
The aqueous medium means water or a mixed medium of water and a hydrophilic organic solvent such as a lower alcohol. In the present invention, only water is preferable.

  In order to disperse the components of the coating solution for forming the intermediate layer, especially inorganic oxide fine particles in an aqueous medium, a general dispersing machine such as a paint shaker, ball mill, sand mill, ball mill, sand mill, attritor, vibration mill, ultrasonic dispersion A general pulverizer such as a pulverizer may be used.

In order to stabilize the dispersion, a dispersion stabilizer may be added to the intermediate layer forming coating solution.
Examples of the dispersion stabilizer include Sanyo Kasei Co., Ltd., product names: Caribon L-400, Elestat AP 130, Sunspear PS 8, PDN-173, Ionette S-85 and New Pole PE-61, San Nopco Co., Ltd. Product name: Rome PWA-40, Nobco Santo RFA, SN Dispersant 2060, 5020, 5029, 5468, 7347C and SN Wet P, manufactured by Nissin Chemical Industry Co., Ltd., Product name: Surfinol 104E and Olphin PD-003, Kao Product name: Poise 520, 530, Homogenol L 100, Daiichi Kogyo Seiyaku Co., Ltd., Charoru AN-103P, AH-144P, Discoat N-14, Toho Chemical Industry Co., Ltd., Product name: Dibrozin A-100, Neoscope 30 etc. And the like.

  In the photoreceptor of the present invention, at least an intermediate layer and an organic photosensitive layer are laminated in this order on a conductive support, and the intermediate layer supports the coating solution for forming an intermediate layer of the present invention. It is obtained by coating on the body and curing the resulting coating film. The photoreceptor of the present invention will be specifically described with reference to the drawings.

1 to 3 are schematic cross-sectional views showing the structure of the main part of the photoreceptor of the present invention.
FIG. 1 shows the structure of the main part of a laminated photoreceptor in which the photosensitive layer is a laminated photosensitive layer in which a charge generation layer and a charge transport layer are laminated in this order (also referred to as “function-separated photosensitive layer”). It is a schematic cross section.
FIG. 2 is a schematic cross-sectional view showing the configuration of the main part of a laminated photoreceptor, which is an inverted two-layer laminated photosensitive layer in which a charge transport layer and a charge generation layer are laminated in this order.
FIG. 3 is a schematic cross-sectional view showing the configuration of the main part of a single-layer type photoreceptor that is a single-layer type photosensitive layer having a single photosensitive layer.
1 and 2 may be any, but the multilayer photosensitive layer of FIG. 1 is preferred.

In the photoreceptor of FIG. 1, an intermediate layer 2, a charge generation layer 3 containing a charge generation material, and a charge transport layer 4 containing a charge transport material are laminated in this order on the surface of a conductive support 1. The laminated photosensitive layer 5 is formed in this order.
In the photoreceptor of FIG. 2, an intermediate layer 2, a charge transport layer 4 containing a charge transport material, and a charge generation layer 3 containing a charge generation material are laminated in this order on the surface of the conductive support 1. The reverse two-layer type laminated photosensitive layer 5 is formed in this order.
In the photoreceptor of FIG. 3, an intermediate layer 2, a single-layer type photosensitive layer 5 ′ containing a charge generation material and a charge transport material are formed in this order on the surface of the conductive support 1.

[Conductive support 1]
The conductive support serves as an electrode for the photoreceptor and also functions as a support member for other layers.
The constituent material of the conductive support is not particularly limited as long as it is a material used in this field.
Specifically, metals and alloy materials such as aluminum, aluminum alloy, copper, brass, zinc, nickel, stainless steel, chromium, molybdenum, vanadium, indium, titanium, gold, platinum: polyethylene terephthalate, polyamide, polyester, polyoxy Polymer material such as methylene, polystyrene, cellulose, polylactic acid, hard paper, glass substrate laminated with metal foil, metal material or alloy material deposited, conductive polymer, tin oxide, oxidation Examples thereof include those obtained by depositing or applying a layer of a conductive compound such as indium or carbon black.
Examples of the shape of the conductive support include a sheet shape, a cylindrical shape, a columnar shape, and an endless belt (seamless belt) shape. Among these, a cylindrical or columnar conductive support having a diameter of 10 to 180 mm is preferable.

If necessary, the surface of the conductive support is subjected to irregular reflection treatment such as anodizing film treatment, surface treatment with chemicals, hot water, coloring treatment, and surface roughening within a range that does not affect the image quality. May be given.
The irregular reflection treatment is particularly effective when the photoreceptor according to the present invention is used in an electrophotographic process using a laser as an exposure light source. That is, in the electrophotographic process using a laser as an exposure light source, the wavelength of the laser beam is uniform, so the laser beam reflected on the surface of the photoconductor and the laser beam reflected inside the photoconductor cause interference, Interference fringes due to this interference may appear in the image and cause image defects. Therefore, by performing irregular reflection processing on the surface of the conductive support, it is possible to prevent image defects due to interference of laser light having a uniform wavelength.

[Intermediate layer (also called “undercoat layer”) 2]
The intermediate layer has a function of preventing charge injection from the conductive support to the single-layer type photosensitive layer or the laminated type photosensitive layer. That is, the decrease in chargeability of the single-layer type photosensitive layer or the multilayer type photosensitive layer is suppressed, the decrease in surface charge other than the portion to be erased by exposure is suppressed, and the occurrence of image defects such as fog is prevented. In particular, during image formation by the reversal development process, it is possible to prevent the occurrence of image fogging called black spots in which minute black dots made of toner are formed on a white background portion.

In addition, the intermediate layer covering the surface of the conductive support reduces the degree of unevenness, which is a defect on the surface of the conductive support, makes the surface uniform, and forms a single layer type photosensitive layer or a multilayer type photosensitive layer. And the adhesion (adhesiveness) between the conductive support and the single-layer type photosensitive layer or the multilayer type photosensitive layer can be improved.
The intermediate layer is obtained, for example, by applying the above-described intermediate layer forming coating solution to the surface of the intermediate layer formed on the conductive support and curing the resulting coating film.

In the case of a sheet, the application method of the intermediate layer forming coating solution is the Baker applicator method, bar coater method (for example, wire bar coater method), casting method, spin coating method, roll method, blade method, bead method, curtain method. In the case of a drum, a spray method, a vertical ring method, a dip coating method and the like can be mentioned.
From these coating methods, an optimum method can be selected in consideration of physical properties and productivity of the coating liquid. In particular, a dip coating method, a blade method and a spray method are suitable.

  The dip coating method is a method of forming a layer on the conductive support 1 by immersing the conductive support 1 in a coating tank filled with a coating solution, and then pulling it up at a constant speed or a sequentially changing speed. Since this method is relatively simple and excellent in terms of productivity and cost, it is widely used for manufacturing a photoreceptor. In addition, you may provide the coating liquid dispersion | distribution apparatus represented by the ultrasonic generator in the apparatus used for the dip coating method in order to stabilize the dispersibility of a coating liquid.

  When the coating agent is removed from the blocked isocyanate compound, the resin having one or more active hydrogen-containing groups capable of reacting with the isocyanate group in the blocked isocyanate compound starts an addition reaction with the isocyanate compound, and the resin is crosslinked. Thermal curing is preferable.

The heat curing can be performed using a known apparatus such as a hot air drying furnace and a far-infrared drying furnace, and the conditions may be appropriately set depending on the type of block isocyanate compound or resin used, the mixing ratio, etc. The temperature is 110 to 150 ° C, preferably 130 to 150 ° C, and the time is about 10 minutes to 1 hour.
Although the film thickness of an intermediate | middle layer is not specifically limited, 0.1-20 micrometers is preferable and 0.5-10 micrometers is especially preferable. If the film thickness of the intermediate layer is less than 0.1 μm, the film substantially does not function as an intermediate layer, and a uniform surface property cannot be obtained by covering defects of the conductive support, and carriers are injected from the conductive support. May not be prevented, and the chargeability may be reduced. On the other hand, when the film thickness of the intermediate layer exceeds 20 μm, it is difficult to form a uniform coating film, and the sensitivity of the photoreceptor may be lowered.

The intermediate layer in the photoreceptor of the present invention may be not only a single layer but also a plurality of layers.
For example, a first intermediate layer (conductive layer) having a thickness of 2 to 20 μm containing conductive inorganic oxide fine particles and a second intermediate layer (insulating layer) having a thickness of 0.2 to 1 μm not containing inorganic oxide fine particles In combination, a first intermediate layer (insulating layer or blocking layer) having a film thickness of 0.2 to 1 μm containing no inorganic oxide fine particles and conductive inorganic oxide fine particles (particle diameter of 400 to 800 nm) on the first intermediate layer. Examples thereof include a combination with a second intermediate layer (moire prevention layer) having a film thickness of 3 to 10 μm.

[Photosensitive layer 5]
The photosensitive layer in the electrophotographic photosensitive member according to the present invention includes, on the intermediate layer formed on the conductive support, a charge generation layer containing at least a charge generation material and a charge transport layer containing at least a charge transport material in this order. It is a laminated type photosensitive layer or an inversely laminated type photosensitive layer, or a single-layer type photosensitive layer containing at least a charge generating substance and a charge transporting substance.

[Charge transport material]
The charge transport material contained in the photosensitive layer in the invention has the following general formula (I):

(In the formula, R, R _{1 to} R ₇ , a to f and g are as defined in the general formula (I)).
It is a triphenylamine compound shown by these.
In the triphenylamine compound of the above general formula (I), when the β-aryl diaryl groups of β-arylstilbene bonded to the nitrogen atom in the molecule are the same, transstilbene and cis stilbene are added to the stilbene skeleton. There is no distinction. However, when the β-position diaryl groups are different from each other, the triphenylamine compound of the general formula (I) can include both β-aryl-trans stilbene and β-aryl-cis stilbene.

In the charge transport material contained in the photosensitive layer in the present invention, preferably, R is a methyl group, a 2,2-diphenylethenyl group, or a 2,2-di (p-methyl) phenylethenyl group.
In the charge transport material contained in the photosensitive layer in the present invention, preferably, the above ag are integers of 0 to 2, and the R _{1 to} R ₇ are 2-methyl, 3-methyl and / or 4 -A triphenylamine compound which is a methyl group.

Furthermore, the charge transport material contained in the photosensitive layer in the present invention is preferably such that R is a methyl group, a 2,2-diphenylethenyl group or a 2,2-di (p-methyl) phenylethenyl group, The a to d are integers of 0 to 2, the e and f are 0, the g is 0 or 1, and the R _{1 to} R ₅ are 2-methyl, 3-methyl and / or 4 -A triphenylamine compound which is a methyl group.

The charge transport material contained in the photosensitive layer in the present invention is more preferably:
R is a methyl group, a to d and g are 1, e and f are 0, R _{1 to} R ₄ are 4-methyl groups, and R ₇ is a 2-methyl group. Formula (1):
A compound (1) represented by:

The R is a methyl group, the a to f are 0, the g is 1, the R ₇ is a 2-methyl group, and the formula (2):
A compound (2) represented by:

The R is a 2,2-diphenylethenyl group, the a to f are 0, the g is 1, the R ₇ is a 2-methyl group, and the formula (3):
Compound (3) represented by

R is a 2,2-diphenylethenyl group, a to g are 0, and the formula (4):
Compound (4) represented by

The R is a 2,2-di (p-methyl) phenylethenyl group, the a to d are 1, the e to g are 0, and the R _{1 to} R ₄ are 4-methyl groups. Yes, formula (5):
Or a compound (5) represented by

The R is a methyl group, the a to d are 1, the e to g are 0, the R _{1 to} R ₄ are 4-methyl groups, and the formula (6):
It is a triphenylamine compound which is a compound (6) represented by these.

Said compounds (1)-(6) are each synthesize | combined by the reaction scheme shown below.
The compound (1) represented by the formula (1) can be synthesized according to the following schemes 1 to 4.
Scheme 1

  4,4′-dimethylbenzophenone (manufactured by Aldrich, product number: 22,527-4, CAS registration number: 611-97-2) and anhydrous methanol (manufactured by Aldrich, product number: 32,241-5, CAS registration number: 67) -56-1), reduced with sodium borohydride (manufactured by Aldrich, product number: 21,346-2, CAS registration number: 16940-66-2). (Aldrich, product number: 28,450-5, CAS registration number: 107-06-2), phosphorus tribromide (Aldrich, product number: 25,653-6, CAS registration number: 7789-60-8) The compound (i) can be obtained according to the above scheme 1.

Scheme 2
Add triethyl phosphite (manufactured by Aldrich, product number: T6,120-4, CAS registration number: 122-52-1) to compound (i) obtained according to Scheme 1 above, and heat at 100 to 120 ° C. By reacting, compound (ii) can be obtained according to Scheme 2 above.

Scheme 3
To the compound (ii) obtained according to the above scheme 2, 4-bromobenzaldehyde (manufactured by Aldrich, product number: B5,740-0, CAS registration number: 1122-91-4) was added at 0 ° C. in a THF solvent. And according to Scheme 3 above, compound (iii) can be obtained as an aryl stilbene derivative.

Scheme 4
2,4-Dimethylaniline (manufactured by Aldrich, product number: 24,091-5, CAS registration number: 95-68-1) was converted to arylamino in the presence of a palladium catalyst in the presence of a palladium catalyst. The compound (1) can be synthesized by substituting the amino group of the aniline derivative according to Scheme 4 above.

Bromodiphenylmethane (manufactured by Aldrich, product number: B6,540-3, CAS registration number: 776-74-9) instead of the compound (i) used in Scheme 2 above:
And according to scheme 2 formula (iv):

Then, compound (iv) represented by formula (v) is synthesized, and then using this compound, according to scheme 3, formula (v):

Compound (v) represented by the above formula (2) is synthesized by using the above-mentioned compound (v) instead of compound (iii) in Scheme 4 above.

(2) can be synthesized.

Scheme 5

4-Nitrobenzaldehyde (manufactured by Aldrich, product number: 13,017-6, CAS registration number: 555-16-8) and chloromethane (manufactured by Aldrich, product number: 29,550-7, CAS registration number: 74-87-3 ) Was subjected to Friedel-Crafts alkylation reaction in the presence of AlCl _{3 by} a conventional method to give 4-nitro-3-methylbenzaldehyde. A nitrobenzene derivative is synthesized by reacting this compound with the above compound (iv) at 0 ° C. in a THF solvent in the same manner as in the above scheme 3. This compound is reacted with tin chloride in an aqueous acid solution to reduce the nitro group to produce an aniline derivative. Further, this aniline derivative was subjected to an arylamination reaction in the presence of a palladium catalyst according to the above-mentioned scheme 5 in the presence of a palladium catalyst, and the amino group of the aniline derivative was substituted to give compound (3). Can be synthesized.

Scheme 6

  4-Nitrobenzaldehyde (manufactured by Aldrich, product number: 13,017-6, CAS registration number: 555-16-8) was prepared in the same manner as in the above Scheme 3 using the above compound (iv) in a THF solvent. Nitrobenzene derivatives are synthesized by reacting at 0 ° C. This compound is reacted with tin chloride in an aqueous acid solution to reduce the nitro group to produce an aniline derivative. Further, this aniline derivative was subjected to an arylamination reaction in the presence of a palladium catalyst according to the above-mentioned scheme 6 in the presence of a palladium catalyst, and the amino group of the aniline derivative was substituted to give compound (4). Can be synthesized.

Scheme 7

  4-Nitrobenzaldehyde (manufactured by Aldrich, product number: 13,017-6, CAS registration number: 555-16-8) was prepared in the same manner as in the above scheme 6 using the compound (ii) in a THF solvent. Nitrobenzene derivatives are synthesized by reacting at 0 ° C. This compound is reacted with tin chloride in an aqueous acid solution to reduce the nitro group to produce an aniline derivative. Further, this aniline derivative was subjected to an arylamination reaction in the presence of a palladium catalyst according to the above-mentioned scheme 7 in the presence of a palladium catalyst, and the amino group of the aniline derivative was substituted to give compound (5). Can be synthesized.

Scheme 8
In the above scheme 4, p-toluidine (manufactured by Aldrich, product number: 23,631-4, CAS registry number: 106-49-0) was used instead of 2,4-dimethylaniline, Compound (6) can be synthesized by subjecting the compound (iii) to an arylamination reaction in the presence of a palladium catalyst and substituting the amino group of the aniline derivative.

By using the triphenylamine compound represented by the general formula (I) according to the present invention, the binder resin can be sacrificed at the expense of electrical characteristics as in the case of using a normal charge transporting substance, because the mechanical durability is excellent. The durability of the photoreceptor can be improved without increasing the content of.
Therefore, the life of the electrophotographic photosensitive member can be extended. Moreover, since the triphenylamine compounds represented by the chemical formulas (1) to (6) can be easily produced, the productivity of the electrophotographic photosensitive member can be improved.

[Laminated Photosensitive Layer 5]
The laminated photosensitive layer 5 includes a charge generation layer 3 and a charge transport layer 4. As described above, by assigning the charge generation function and the charge transport function to separate layers, the optimum material constituting each layer can be independently selected.
In the following description, a stacked photosensitive layer (FIG. 1) in which a charge generation layer and a charge transport layer are stacked in this order will be described. In the case of an inverted two-layer stacked photosensitive layer (FIG. 2), It is basically the same except that the stacking order is different.

[Charge generation layer 3]
The charge generation layer is mainly composed of a charge generation material having a charge generation capability of generating charges by absorbing irradiated light, and optionally contains a known additive and a binder resin (binder).
As the charge generation material, a compound used in this field can be used.

Specifically, an azo pigment (having a carbazole skeleton, a styryl stilbene skeleton, a triphenylamine skeleton, a dibenzothiophene skeleton, an oxadiazole skeleton, a fluorenone skeleton, a bis-stilbene skeleton, a distyryl oxadiazole skeleton, or a distyryl carbazole skeleton. Monoazo pigments, bisazo pigments, trisazo pigments, etc.) perylene pigments (perylene imide, perylene acid anhydride, etc.); polycyclic quinone pigments (quinacridone, anthraquinone, pyrenequinone, etc.); phthalocyanine pigments (metal phthalocyanine, no Metal phthalocyanines, halogenated metal-free phthalocyanines, etc.); indigo pigments (indigo, thioindigo, etc.); squarylium dyes, azurenium dyes, thiopyrylium dyes, pyrylium salts, triphenylmethane Organic pigments or dyes such as dyes, further selenium, inorganic materials such as amorphous silicon.
These charge generating materials can be used alone or in combination of two or more.
Among these charge generation materials, phthalocyanine pigments, azo pigments, and perylene pigments are particularly preferable because of their high sensitivity.

  The charge generation layer is a chemical sensitizer, an optical sensitizer, an antioxidant, an ultraviolet absorber, a dispersion stabilizer, a sensitizer, a leveling agent, a plasticizer, as long as the preferable characteristics of the present invention are not impaired. An appropriate amount of one or more known additives selected from fine particles of inorganic compounds or organic compounds may be contained. These additives may be contained in the charge transport layer described later, or may be contained in both the charge generation layer and the charge transport layer.

The chemical sensitizer and the optical sensitizer improve the sensitivity of the photoreceptor, suppress an increase in residual potential and fatigue due to repeated use, and improve electrical durability.
Examples of chemical sensitizers include acid anhydrides such as succinic anhydride, maleic anhydride, phthalic anhydride, and 4-chloronaphthalic anhydride; cyano compounds such as tetracyanoethylene and terephthalmalondinitrile, 4-nitrobenzaldehyde, and the like. Aldehydes; anthraquinones such as anthraquinone and 1-nitroanthraquinone; polycyclic or heterocyclic nitro compounds such as 2,4,7-trinitrofluorenone and 2,4,5,7-tetranitrofluorenone; diphenoquinone compounds Examples thereof include electron-withdrawing materials and those obtained by polymerizing these electron-withdrawing materials.

  Examples of the optical sensitizer include xanthene dyes, quinoline pigments, organic photoconductive compounds such as copper phthalocyanine, triphenylmethane dyes represented by methyl violet, crystal violet, knight blue and victoria blue; erythrosin, Acridine dyes typified by rhodamine B, rhodamine 3R, acridine orange and frappeocin; thiazine dyes typified by methylene blue and methylene green; oxazine dyes typified by capri blue and meldra blue; cyanine dyes; styryl dyes; Examples include pyrylium salt dyes and thiopyrylium salt dyes.

Antioxidants can maintain sensitivity stability over a long period of time.
Antioxidants include phenolic antioxidants such as hindered phenols such as 2,6-di-t-butyl-4-methylphenol (2,6-di-t-butyl-p-cresol: BHT). , Amine antioxidants such as hindered amines, vitamin E, hydroquinone, paraphenylenediamine, arylalkanes and derivatives thereof, organic sulfur compounds, organic phosphorus compounds, etc., and these may be used alone or in combination of two or more. Can be used.

The addition amount of the antioxidant is preferably 0.1 to 40 parts by weight, particularly preferably 0.5 to 15 parts by weight, based on 100 parts by weight of the charge generating material.
If the addition amount of the antioxidant is less than 0.1 part by weight, a sufficient effect may not be obtained for improving the stability of the coating solution and improving the durability of the photoreceptor. On the other hand, if the amount of the antioxidant added exceeds 40 parts by weight, the photoreceptor characteristics may be adversely affected.

Leveling agents and plasticizers can improve film formability, flexibility and surface smoothness.
Examples of the leveling agent include a silicone leveling agent.
Examples of the plasticizer include dibasic acid esters such as phthalate esters, fatty acid esters, phosphate esters, chlorinated paraffins, and epoxy type plasticizers.
Fine particles of an inorganic compound or an organic compound can enhance mechanical strength and improve electrical characteristics. Examples of such fine particles include fine particles exemplified in an intermediate layer described later.

The charge generation layer can be formed by a known dry method and wet method.
Examples of the dry method include a method of vacuum-depositing a charge generating material on the surface of a conductive support.
As the wet method, for example, a charge generating material, and optionally an additive and a binder resin are dissolved or dispersed in an appropriate organic solvent to prepare a coating solution for forming a charge generating layer, and this coating solution is used as a conductive support. The method of apply | coating to the intermediate | middle layer surface formed above, and then drying and removing an organic solvent is mentioned.

The binder resin can improve the mechanical strength and durability of the charge generation layer, the binding property between layers, and the like, and a resin having a binding property used in this field can be used.
Specifically, vinyl resins such as polymethyl methacrylate, polystyrene, polyvinyl chloride, polycarbonate, polyester, polyester carbonate, polysulfone, polyarylate, polyamide, methacrylic resin, acrylic resin, polyether, polyacrylamide, polyphenylene oxide, etc. Thermoplastic resin; epoxy resin, silicone resin, polyurethane, phenol resin, alkyd resin, melamine resin, phenoxy resin, polyvinyl butyral, polyvinyl formal, and other thermosetting resins, partially crosslinked products of these resins, included in these resins Copolymer resins containing two or more of the structural units (vinyl chloride-vinyl acetate copolymer resin, vinyl chloride-vinyl acetate-maleic anhydride copolymer resin, acrylonitrile-styrene) Insulation, such copolymer resins resins). These binder resins can be used alone or in combination of two or more.

The mixing ratio of the charge generation material and the binder resin is not particularly limited, but the charge generation material is usually about 10 to 99% by weight.
When the charge generation material is less than 10% by weight, the sensitivity of the photoreceptor may be lowered.
On the other hand, when the charge generation material exceeds 99% by weight, not only the film strength of the charge generation layer decreases, but also the dispersibility of the charge generation material decreases and coarse particles may increase. For this reason, surface charges other than those that should be erased by exposure are reduced, and image fogging, particularly fogging of an image called black spots where toner adheres to a white background and minute black spots are formed may increase.

Examples of the organic solvent include aromatic hydrocarbons such as benzene, toluene, xylene, mesitylene, tetralin, diphenylmethane, dimethoxybenzene, and dichlorobenzene; halogenated hydrocarbons such as dichloromethane, dichloroethane, and tetrachloropropane; tetrahydrofuran (THF) , Ethers such as dioxane, dibenzyl ether, dimethoxymethyl ether, 1,2-dimethoxyethane; ketones such as methyl ethyl ketone, cyclohexanone, acetophenone, isophorone; esters such as methyl benzoate, ethyl acetate, butyl acetate, diphenyl sulfide Sulfur-containing solvents such as: Fluoro-based solvents such as hexafluoroisopropanol; aprotic electrodes such as N, N-dimethylformamide and N, N-dimethylacetamide Solvent and the like, which may be used alone or as a mixed solvent.
A mixed solvent obtained by adding alcohols, acetonitrile, or methyl ethyl ketone to such a solvent can also be used. Among these solvents, non-halogen organic solvents are preferably used in consideration of the global environment.

Prior to dissolving or dispersing the constituent materials in the resin solution, the charge generating material may be pre-ground.
The preliminary pulverization can be performed using, for example, a general pulverizer such as a ball mill, a sand mill, an attritor, a vibration mill, or an ultrasonic disperser.
The dissolution or dispersion of the constituent materials in the resin solution can be performed using, for example, a general disperser such as a paint shaker, a ball mill, or a sand mill. At this time, it is preferable to appropriately set the dispersion condition so that impurities are generated from the container and the members constituting the disperser due to wear and the like and are not mixed into the coating liquid.

The application method of the charge generation layer forming coating solution is a baker applicator method, a bar coater method, a casting method, a spin coating method, a roll method, a blade method or the like in the case of a sheet, and a spray method or a vertical ring method in the case of a drum. And a dip coating method.
Although it will not specifically limit if the temperature in the drying process of a coating film is the temperature which can remove the used organic solvent, 50-140 degreeC is suitable and 80-130 degreeC is especially preferable.
When the drying temperature is less than 50 ° C., the drying time may be long. On the other hand, if the drying temperature exceeds 140 ° C., the electrical characteristics during repeated use of the photoreceptor may deteriorate and the resulting image may deteriorate.

  The thickness of the charge generation layer is not particularly limited, but is preferably 0.05 to 5 μm, particularly preferably 0.1 to 1 μm. When the thickness of the charge generation layer is less than 0.05 μm, the light absorption efficiency is lowered and the sensitivity may be lowered. On the other hand, when the film thickness of the charge generation layer exceeds 5 μm, charge transport inside the charge generation layer becomes a rate-determining step in the process of erasing charges on the surface of the photoreceptor, and the sensitivity may be lowered.

[Charge transport layer]
The charge transport layer in the present invention mainly comprises a binder resin and a triphenylamine compound represented by the general formula (I), more specifically, a triphenylamine compound represented by the compounds (1) to (7). Contains as a charge transport material.

  Usually, the ratio E / B between the weight E of the charge transport material and the weight B of the binder resin is 10/12 to 10/25, preferably 10/16 to 10/20. When the ratio E / B is less than 10/25, the relative amount ratio of the binder resin to the charge transport material becomes high, and sufficient sensitivity may not be obtained. On the other hand, when the ratio E / B exceeds 10/12, the printing durability of the charge transport layer and the durability of the photoreceptor may be lowered.

As the binder resin, one or more of the same binder resins as those contained in the charge generation layer can be used. Among these resins, polycarbonate-based resins, polyarylate resins and polystyrene resins are photochemically stable, excellent in compatibility with charge transport materials, and have a volume resistance of 10 ¹³ Ω or more. It is preferable because it is excellent in electrical insulation and has excellent film forming properties and potential characteristics.

The charge transport layer may contain an appropriate amount of the same additive as that contained in the charge generation layer, if necessary, within the range not impairing the effects of the present invention.
The charge transport layer is prepared by dissolving or dispersing a charge transport material, a binder resin and, if necessary, other additives in a suitable organic solvent to prepare a coating solution for forming a charge transport layer. It can be formed by applying to the surface and then drying to remove the organic solvent.

More specifically, for example, a coating liquid for forming a charge transport layer is prepared by dissolving or dispersing a charge transport material and other additives as required in a resin solution obtained by dissolving a binder resin in an organic solvent. To do.
Other processes and conditions are in accordance with the formation of the charge generation layer.

  Although the film thickness of a charge transport layer is not specifically limited, 10-60 micrometers is preferable and 10-40 micrometers is especially preferable. If the thickness of the charge transport layer is less than 10 μm, the charge retention ability may be reduced. Conversely, if the thickness of the charge transport layer is more than 60 μm, the sharpness is reduced and the residual potential is increased. Image degradation may occur significantly.

[Single layer type photosensitive layer 5 ']
The single-layer type photosensitive layer contains a charge generation material, a charge transport material represented by the general formula (I), and a binder resin (binder) as main components.
The single-layer type photosensitive layer may contain an appropriate amount of the same additive as that contained in the charge generation layer, if necessary, within the range not impairing the effects of the present invention.
A single-layer type photosensitive layer is prepared by dissolving and / or dispersing a charge generation material, a charge transport material and other additives as required in a suitable organic solvent to prepare a coating solution for forming a single-layer type photosensitive layer. It can be formed by applying the coating solution to the surface of the intermediate layer formed on the conductive support, and then drying to remove the organic solvent.

Other processes and conditions are in accordance with the formation of the charge generation layer and the charge transport layer.
The film thickness of the single-layer type photosensitive layer is not particularly limited, but is preferably 10 to 100 μm, and particularly preferably 15 to 50 μm. If the film thickness of the single-layer type photosensitive layer is less than 10 μm, the charge holding ability on the surface of the photoreceptor may be lowered, and if the film thickness of the single-layer type photosensitive layer exceeds 100 μm, the productivity may be lowered. is there.

[Protective layer (not shown)]
The photoreceptor of the present invention may have a protective layer (not shown) on the surface of the multilayer photosensitive layer 5 and the single-layer photosensitive layer 5 ′.
The protective layer has functions of improving the abrasion of the photosensitive layer and preventing chemical adverse effects caused by ozone, nitrogen oxides, and the like.
The protective layer is prepared by, for example, preparing a protective layer-forming coating solution by dissolving or dispersing a binder resin in an appropriate organic solvent and, if necessary, an additive such as an antioxidant or an ultraviolet absorber. It can be formed by applying a coating solution on the surface of a single-layer type photosensitive layer or a laminated type photosensitive layer, and removing the organic solvent by drying.

Other processes and conditions are in accordance with the formation of the charge generation layer.
The thickness of the protective layer is not particularly limited, but is preferably 0.5 to 10 μm, and particularly preferably 1 to 5 μm. If the thickness of the surface protective layer 5 is less than 0.5 μm, the surface resistance of the photoreceptor is inferior and the durability may be insufficient. Conversely, if it exceeds 10 μm, the resolution of the photoreceptor may be reduced. There is.

  The image forming apparatus of the present invention includes a photosensitive member of the present invention, a charging unit that charges the photosensitive member, an exposure unit that exposes the charged photosensitive member, and an electrostatic latent image formed by the exposure. Developing means for forming a toner image, transfer means for transferring the developed toner image onto the recording material, fixing means for fixing the transferred toner image on the recording material to form an image, and a photoconductor At least a cleaning unit that removes and collects toner remaining on the photosensitive member, and a neutralizing unit that neutralizes surface charge remaining on the photosensitive member.

The image forming apparatus of the present invention will be described with reference to the drawings, but is not limited to the following description.
FIG. 4 is a schematic side view showing the configuration of the image forming apparatus of the present invention.
The image forming apparatus 20 in FIG. 4 includes a photoreceptor 21 of the present invention (for example, one of the photoreceptors in FIGS. 1 to 3), a charging unit (charger) 24, an exposure unit 28, and a developing unit ( A developing unit) 25, a transfer unit (transfer unit) 26, a cleaning unit (cleaner) 27, a fixing unit (fixing unit) 31, and a charge eliminating unit (not shown, provided together with the cleaning unit 27). Consists of. Reference numeral 30 denotes a transfer sheet.

The photosensitive member 21 is rotatably supported by the main body of the image forming apparatus 20 (not shown), and is driven to rotate in the direction of the arrow 23 around the rotation axis 22 by a driving unit (not shown).
The drive means includes, for example, an electric motor and a reduction gear, and transmits the driving force to a conductive support constituting the core of the photoconductor 21, thereby rotating the photoconductor 21 at a predetermined peripheral speed. .

The charger 24, the exposure unit 28, the developing unit 25, the transfer unit 26, and the cleaner 27 are arranged in this order along the outer peripheral surface of the photoconductor 21 from the upstream side in the rotation direction of the photoconductor 21 indicated by the arrow 23. It is provided toward the side.
The charger 24 is a charging unit that charges the outer peripheral surface of the photoconductor 21 to a predetermined potential. Specifically, for example, the charger 24 is realized by a contact-type charging roller 24a, a charging brush, or a charger wire such as a corotron or a scorotron. Reference numeral 24b denotes a bias power source.

The exposure unit 28 includes, for example, a semiconductor laser as a light source, and is charged by irradiating exposure light 28a such as a laser beam output from the light source between the charger 24 and the developing unit 25 of the photosensitive member 21. The outer peripheral surface of the photoreceptor 21 is exposed according to the image information. The exposure light 28 a is repeatedly scanned in the main scanning direction in the direction in which the rotation axis 22 of the photoconductor 21 extends, and accordingly, electrostatic latent images are sequentially formed on the surface of the photoconductor 21.
The developing unit 25 is a developing unit that develops an electrostatic latent image formed on the surface of the photoreceptor 21 by exposure with a developer. The developing unit 25 is provided facing the photoreceptor 21, and applies toner to the outer peripheral surface of the photoreceptor 21. A developing roller 25a to be supplied and a casing 25b for supporting the developing roller 25a so as to be rotatable around a rotation axis parallel to the rotation axis 22 of the photosensitive member 21 and containing a developer containing toner in the internal space thereof.

The transfer device 26 supplies a toner image, which is a visible image formed on the outer peripheral surface of the photoconductor 21 by development, between the photoconductor 21 and the transfer device 26 from the direction of the arrow 29 by a conveying unit (not shown). It is a transfer means for transferring onto the transfer paper 30 as a recording medium. The transfer unit 26 is, for example, a non-contact type transfer unit that includes a charging unit and transfers the toner image onto the transfer paper 30 by applying a charge having a polarity opposite to that of the toner to the transfer paper 30.
The cleaner 27 is a cleaning unit that removes and collects toner remaining on the outer peripheral surface of the photoconductor 21 after the transfer operation by the transfer device 26, and includes a cleaning blade 27 a that peels off toner remaining on the outer peripheral surface of the photoconductor 21, and a cleaning device. A recovery casing 27b for storing the toner separated by the blade 27a. The cleaner 27 is provided together with a charge eliminating lamp (not shown).

Further, the image forming apparatus 20 is provided with a fixing device 31 as fixing means for fixing the transferred image on the downstream side where the transfer paper 30 that has passed between the photoreceptor 21 and the transfer device 26 is conveyed. . The fixing device 31 includes a heating roller 31a having a heating unit (not shown), and a pressure roller 31b that is provided to face the heating roller 31a and is pressed by the heating roller 31a to form a contact portion.
The image forming operation by the image forming apparatus 20 is performed as follows. First, when the photosensitive member 21 is rotationally driven in the direction of the arrow 23 by the driving means, the charger 24 provided upstream in the rotational direction of the photosensitive member 21 with respect to the imaging point of the exposure light 28a by the exposure means 28 The surface of the body 21 is uniformly charged to a predetermined positive or negative potential.

Next, exposure light 28 a corresponding to image information is irradiated from the exposure means 28 to the surface of the photoreceptor 21. With this exposure, the surface charge of the portion irradiated with the exposure light 28a is removed from the surface of the photosensitive member 21, and the surface potential of the portion irradiated with the exposure light 28a and the surface potential of the portion not irradiated with the exposure light 28a are reduced. A difference occurs and an electrostatic latent image is formed.
Toner is supplied to the surface of the photosensitive member 21 on which the electrostatic latent image is formed from a developing unit 25 provided on the downstream side in the rotation direction of the photosensitive member 21 with respect to the imaging point of the exposure light 28a by the exposure unit 28. The latent image is developed to form a toner image.

In synchronization with the exposure of the photosensitive member 21, the transfer paper 30 is supplied between the photosensitive member 21 and the transfer device 26. The transfer device 26 applies a charge having a polarity opposite to that of the toner to the supplied transfer paper 30, and the toner image formed on the surface of the photoreceptor 21 is transferred onto the transfer paper 30.
The transfer paper 30 onto which the toner image has been transferred is conveyed to a fixing device 31 by a conveying means, and is heated and pressurized when passing through a contact portion between a heating roller 31a and a pressure roller 31b of the fixing device 31, and toner The image is fixed on the transfer paper 30 and becomes a robust image. The transfer paper 30 on which the image is formed in this way is discharged to the outside of the image forming apparatus 20 by the conveying means.

  On the other hand, the toner remaining on the surface of the photoconductor 21 even after the transfer of the toner image by the transfer unit 26 is separated from the surface of the photoconductor 21 by the cleaner 27 and collected. The charge on the surface of the photoconductor 21 from which the toner has been removed in this manner is removed by the light from the static elimination lamp, and the electrostatic latent image on the surface of the photoconductor 21 disappears. Thereafter, the photosensitive member 21 is further driven to rotate, and a series of operations starting from charging is repeated to continuously form images.

  EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to these examples.

Example 1
As the conductive support, a cylindrical conductive support made of aluminum having a diameter of 30 mm, a length of 357 mm, and a thickness of 0.8 mm was used to produce the photoreceptor shown in FIG.
First, fine particles of dendritic titanium oxide surface-treated with aluminum oxide (Al ₂ O ₃ ) and zirconium dioxide (ZrO ₂ ) as inorganic oxide fine particles (average primary particle size: minor axis 40-70 nm, major axis 200 ˜300 nm, manufactured by Ishihara Sangyo Co., Ltd., product name: TTO-D-1) 12 parts by weight; aqueous polyacrylic polyol (solid content: 45%, OH number: 80, manufactured by DIC Corporation, product name: Burnock WE) -300) 8.4 parts by weight; and blocked isocyanate compound (solid content: 40%, NCO content: 5.4%, manufactured by Mitsui Chemicals Polyurethanes, product name: Takenate WB-920) 10.5 parts by weight; Was added to 69 parts by weight of water and dispersed using a paint shaker for 6 hours to prepare a coating solution for forming an intermediate layer (total amount: 1 kg).

The isocyanate group (H) of the blocked isocyanate compound is 1.0 molar ratio (H / B) to the active hydrogen-containing group (B) of the resin, and the inorganic oxide fine particles (P) are crosslinked resin (block isocyanate). The weight ratio (P / R) was 6/4 with respect to the sum of compounds and resins: R).
The obtained coating solution for forming an intermediate layer is filled in a coating tank in the same manner as in Example 1, and the conductive support is dipped and then pulled up, and the obtained coating film is dried and cured at a temperature of 150 ° C. for 30 minutes to form a film. An intermediate layer having a thickness of 1.0 μm was formed.

Next, 2 parts by weight of Y-type oxotitanium phthalocyanine (manufactured by Nippon Materials Co., Ltd.) as a charge generating substance; 1 part by weight of polyvinyl butyral resin (manufactured by Sekisui Chemical Co., Ltd., product name: ESREC B BM-S) as a binder resin; organic 97 parts by weight of methyl ethyl ketone as a solvent was mixed and dispersed using a paint shaker to prepare a coating solution for forming a charge generation layer (total amount: 1 kg).
This charge generation layer forming coating solution was applied on the previously formed intermediate layer by the same dip coating method as that for the intermediate layer, and naturally dried to form a charge generation layer having a thickness of 0.4 μm.

Next, 10 parts by weight of a triphenylamine compound represented by the compound (1) as a charge transport material; 18 parts by weight of a polycarbonate resin (product name: Iupilon Z400, manufactured by Mitsubishi Engineering Plastics Co., Ltd.) as a binder resin; 0.5 parts by weight of 2,6-di-t-butyl-4-methylphenol; and 0.004 parts by weight of dimethylpolysiloxane (manufactured by Shin-Etsu Chemical Co., Ltd., product name: KF-96) as a leveling agent; Then, it was dissolved in 110 parts by weight of tetrahydrofuran (THF) as an organic solvent to prepare a coating solution for forming a charge transport layer (total amount: 1 kg).
This charge transport layer forming coating solution is applied onto the previously formed charge generation layer by the same dip coating method as that for the intermediate layer and dried at a temperature of 130 ° C. for 1 hour to form a charge transport layer having a thickness of 23 μm. did.
The photoreceptor of Example 1 was produced as described above.

Example 2
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the triphenylamine compound of Compound (2) was used instead of Compound (1) of Example 1 as a charge transport material.

Example 3
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the triphenylamine compound of Compound (3) was used instead of Compound (1) of Example 1 as a charge transport material.

Example 4
An electrophotographic photoreceptor was produced in exactly the same manner as in Example 1, except that the triphenylamine compound of Compound (4) was used in place of Compound (1) of Example 1 as a charge transport material.

Example 5
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the triphenylamine compound of Compound (5) was used instead of Compound (1) of Example 1 as a charge transport material.

Example 6
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the triphenylamine compound of Compound (6) was used instead of Compound (1) of Example 1 as the charge transport material.

Example 7
A photoconductor of Example 7 was produced in the same manner as in Example 1 except that the coating solution for forming the intermediate layer was prepared with the following components.
Titanium oxide fine particles (Ishihara Sangyo Co., Ltd., product name: TTO-D-1) 12 parts by weight as inorganic oxide fine particles;
8.4 parts by weight of an aqueous polyacrylic polyol as resin (solid content: 45%, OH value: 80, manufactured by DIC Corporation, product name: Burnock WE-300);
Block isocyanate compound (solid content: 40%, NCO content: 5.4%, manufactured by Mitsui Chemicals Polyurethane Co., Ltd., product name: Takenate WB-920) 10.5 parts by weight;
Antifoaming agent (polyether antifoaming agent, manufactured by San Nopco, product name: SN deformer 470) 0.08 parts by weight; and water 67 parts by weight;
The isocyanate group (H) of the blocked isocyanate compound is 1.0 molar ratio (H / B) to the active hydrogen-containing group (B) of the resin, and the inorganic oxide fine particles (P) are crosslinked resin (block isocyanate). The weight ratio (P / R) was 6/4 with respect to the sum of compounds and resins: R).

Example 8
A photoconductor of Example 8 was produced in the same manner as in Example 1 except that the coating solution for forming an intermediate layer was prepared with the following components.
Titanium oxide fine particles (Ishihara Sangyo Co., Ltd., product name: TTO-D-1) 12 parts by weight as inorganic oxide fine particles;
8.4 parts by weight of an aqueous polyacrylic polyol as resin (solid content: 45%, OH value: 80, manufactured by DIC Corporation, product name: Burnock WE-300);
Block isocyanate compound (solid content: 40%, NCO content: 5.4%, manufactured by Mitsui Chemicals Polyurethane Co., Ltd., product name: Takenate WB-920) 10.5 parts by weight;
Antifoaming agent (polyether foam suppressor, manufactured by San Nopco, product name: SN deformer 470) 0.08 parts by weight;
Dispersion stabilizer (manufactured by San Nopco, product name: Roma PWA-40) 0.03 parts by weight; and 67 parts by weight of water;
The isocyanate group (H) of the blocked isocyanate compound is 1.0 molar ratio (H / B) to the active hydrogen-containing group (B) of the resin, and the inorganic oxide fine particles (P) are crosslinked resin (block isocyanate). The weight ratio (P / R) was 6/4 with respect to the sum of compounds and resins: R).

Example 9
A photoconductor of Example 9 was produced in the same manner as in Example 1 except that the coating solution for forming the intermediate layer was prepared with the following components.
Titanium oxide fine particles (Ishihara Sangyo Co., Ltd., product name: TTO-D-1) 12 parts by weight as inorganic oxide fine particles;
Polyether polyol (solid content: 35%, OH value: 60, manufactured by Nippon Polyurethane Industry Co., Ltd., product name: AQD-473) as a resin, 14.3 parts by weight;
Block isocyanate compound (solid content: 42%, NCO content: 7.5%, manufactured by Nippon Polyurethane Industry Co., Ltd., developed product name: BWD-102) 7.1 parts by weight;
Antifoaming agent (polyether foam suppressor, manufactured by San Nopco, product name: SN deformer 470) 0.08 parts by weight;
Dispersion stabilizer (manufactured by San Nopco, product name: SN Dispersant 2060) 0.03 parts by weight;
67 parts by weight of water;
The isocyanate group (H) of the blocked isocyanate compound is 1.0 molar ratio (H / B) to the active hydrogen-containing group (B) of the resin, and the inorganic oxide fine particles (P) are crosslinked resin (block isocyanate). The weight ratio (P / R) was 6/4 with respect to the sum of compounds and resins: R).

Example 10
A photoconductor of Example 10 was produced in the same manner as in Example 1 except that the coating solution for forming the intermediate layer was prepared with the following components.
Titanium oxide fine particles (average primary particle size: 35 nm, manufactured by Teika Co., Ltd., product name: MT-500SAS) as inorganic oxide fine particles 12 parts by weight;
Polyvinyl acetal as resin (solid content: 20%, OH value: 960, manufactured by Sekisui Chemical Co., Ltd., product name: KW-1) 4.0 parts by weight;
10.3 parts by weight of a blocked isocyanate compound (solid content: 70%, NCO content: 7.9%, manufactured by Asahi Kasei Chemicals Corporation, developed product name: X1248);
Defoaming agent (oil compound type, manufactured by San Nopco, product name: SN deformer 777) 0.08 parts by weight;
Dispersion stabilizer (manufactured by Sanyo Chemical Industries, product name: Caribon L-400) 0.03 parts by weight;
74 parts by weight of water;
The isocyanate group (H) of the blocked isocyanate compound is 1.0 molar ratio (H / B) to the active hydrogen-containing (B) group of the resin, and the inorganic oxide fine particles (P) are crosslinked resin (block isocyanate). The weight ratio (P / R) was 6/4 with respect to the sum of compounds and resins: R).

Example 11
A photoconductor of Example 11 was produced in the same manner as in Example 1 except that the coating solution for forming the intermediate layer was prepared with the following components.
Zinc oxide fine particles (average primary particle size: 35 nm, manufactured by Sakai Chemical Industry Co., Ltd., product name: FINEX 30) as inorganic oxide fine particles 12 parts by weight;
Water-soluble cellulose (OH value: 360, manufactured by Shin-Etsu Chemical Co., Ltd., product name: Metroles 65SH-50) 0.96 parts by weight as resin;
Block isocyanate compound (solid content: 37.5%, NCO content: 3.7%, product name: Bihijoule VPLS2310, manufactured by Sumika Bayer Urethane Co., Ltd., product name: Bihijoule VPLS2310) 18.8 parts by weight;
Defoaming agent (oil compound type, manufactured by San Nopco, product name: SN deformer 777) 0.08 parts by weight;
Dispersion stabilizer (manufactured by Sanyo Chemical Industries, product name: Elestat AP-130) 0.03 parts by weight; and 65 parts by weight of water;
The isocyanate group (H) of the blocked isocyanate compound is 1.0 molar ratio (H / B) to the active hydrogen-containing group (B) of the resin, and the inorganic oxide fine particles (P) are crosslinked resin (block isocyanate). The weight ratio (P / R) was 6/4 with respect to the sum of compounds and resins: R).

Example 12
A photoconductor of Example 12 was produced in the same manner as in Example 1 except that the coating solution for forming an intermediate layer was prepared with the following components.
12 parts by weight of zinc oxide fine particles (average primary particle size: 30 to 40 nm, manufactured by Teika Co., Ltd., product name: MZ300) as inorganic oxide fine particles;
8.8 parts by weight of water-soluble nylon (solid content: 20%, NH content: 10%, manufactured by Nagase ChemteX Corporation, product name: Toresin FS-350) as a resin;
Block isocyanate compound (solid content: 45%, NCO content: 7.0%, manufactured by Mitsui Chemicals Polyurethanes, product name: Takenate WB-820) 13.9 parts by weight;
Defoaming agent (oil compound type, manufactured by San Nopco, product name: SN deformer 777) 0.08 parts by weight;
Dispersion stabilizer (manufactured by San Nopco, product name: SN Dispersant 2060) 0.03 parts by weight;
65 parts by weight of water;
The isocyanate group (H) of the blocked isocyanate compound is 1.0 molar ratio (H / B) to the active hydrogen-containing group (B) of the resin, and the inorganic oxide fine particles (P) are crosslinked resin (block isocyanate). The weight ratio (P / R) was 6/4 with respect to the sum of compounds and resins: R).

Example 13
A photoconductor of Example 13 was produced in the same manner as in Example 1 except that the coating solution for forming the intermediate layer was prepared with the following components.
10 parts by weight of tin oxide fine particles (average primary particle size: 30 nm, manufactured by Mitsubishi Materials Corporation, product name: S-2000) as inorganic oxide fine particles;
2.8 parts by weight of polyvinyl acetal as a resin (solid content: 20%, OH value: 960, manufactured by Sekisui Chemical Co., Ltd., product name: KW-1);
13.5 parts by weight of a block isocyanate compound (solid content: 70%, NCO content: 4.3%, manufactured by Asahi Kasei Chemicals Corporation, developed product name: X1458);
Defoaming agent (oil compound type, manufactured by San Nopco, product name: SN deformer 777) 0.08 parts by weight;
Dispersion stabilizer (manufactured by Sanyo Chemical Industries, product name: Caribon L-400) 0.025 parts by weight; and 74 parts by weight of water;
The isocyanate group (H) of the blocked isocyanate compound is 1.0 molar ratio (H / B) to the active hydrogen-containing group (B) of the resin, and the inorganic oxide fine particles (P) are crosslinked resin (block isocyanate). The weight ratio (P / R) was 5/5 with respect to the sum of compounds and resins: R).

Example 14
A photoconductor of Example 14 was produced in the same manner as Example 1 except that the coating solution for forming an intermediate layer was prepared using the following components.
Antimony oxide fine particles (average primary particle size: 100 to 500 nm, manufactured by Nippon Seiko Co., Ltd., product name: PATOX CF) as inorganic oxide fine particles 10 parts by weight;
11.0 parts by weight of water-soluble nylon as resin (solid content: 20%, NH content: 10%, manufactured by Nagase ChemteX Corporation, product name: Toresin FS-350);
Block isocyanate compound (solid content: 45%, NCO content: 7.0%, manufactured by Mitsui Chemicals Polyurethane Co., Ltd., product name: Takenate WB-820) 17.3 parts by weight;
Defoaming agent (oil compound type, manufactured by San Nopco, product name: SN deformer 777) 0.08 parts by weight;
Dispersion stabilizer (manufactured by San Nopco, product name: SN Dispersant 5468) 0.025 parts by weight; and 74 parts by weight of water;
The isocyanate group (H) of the blocked isocyanate compound is 1.0 molar ratio (H / B) to the active hydrogen-containing group (B) of the resin, and the inorganic oxide fine particles (P) are crosslinked resin (block isocyanate). The weight ratio (P / R) was 5/5 with respect to the sum of compounds and resins: R).

Example 15
A photoconductor of Example 15 was produced in the same manner as Example 1 except that the coating solution for forming the intermediate layer was prepared using the following components.
Titanium oxide fine particles (Ishihara Sangyo Co., Ltd., product name: TTO-D-1) 12 parts by weight as inorganic oxide fine particles;
Polyether polyol (solid content: 35%, OH value: 60, manufactured by Nippon Polyurethane Industry Co., Ltd., product name: AQD-473) as a resin 18.4 parts by weight;
Block isocyanate compound (solid content: 42%, NCO content: 7.5%, manufactured by Nippon Polyurethane Industry Co., Ltd., developed product name: BWD-102) 3.7 parts by weight;
Antifoaming agent (polyether, San Nopco, product name: SN deformer 470) 0.08 parts by weight;
Dispersion stabilizer (manufactured by San Nopco, product name: SN Dispersant 2060) 0.03 parts by weight; and 66 parts by weight of water;
The isocyanate group (H) of the blocked isocyanate compound is 0.4 molar ratio (H / B) to the active hydrogen-containing group (B) of the resin, and the inorganic oxide fine particles (P) are crosslinked resin (block isocyanate). The weight ratio (P / R) was 6/4 with respect to the sum of compounds and resins: R).

Example 16
A photoconductor of Example 16 was produced in the same manner as in Example 1 except that the coating solution for forming an intermediate layer was prepared using the following components.
Titanium oxide fine particles (Ishihara Sangyo Co., Ltd., product name: TTO-D-1) 12 parts by weight as inorganic oxide fine particles;
11.7 parts by weight of a polyether polyol (solid content: 35%, OH value: 60, manufactured by Nippon Polyurethane Industry Co., Ltd., product name: AQD-473) as a resin;
Block isocyanate compound (solid content: 42%, NCO content: 7.5%, manufactured by Nippon Polyurethane Industry Co., Ltd., developed product name: BWD-102) 9.3 parts by weight;
Antifoaming agent (polyether, San Nopco, product name: SN deformer 470) 0.08 parts by weight;
Dispersion stabilizer (manufactured by San Nopco, product name: SN Dispersant 2060) 0.03 parts by weight; and 67 parts by weight of water;
The isocyanate group (H) of the blocked isocyanate compound has a molar ratio (H / B) of 1.6 to the active hydrogen-containing group (B) of the resin, and the inorganic oxide fine particles (P) are crosslinked resin (block isocyanate). The weight ratio (P / R) was 6/4 with respect to the sum of compounds and resins: R).

Example 17
A coating solution for forming a first intermediate layer containing no inorganic oxide fine particles was prepared in the same manner as in Example 1 except that the following components were used.
17.9 parts by weight of a polyether polyol (solid content: 35%, OH value: 60, manufactured by Nippon Polyurethane Industry Co., Ltd., product name: AQD-473) as a resin;
8.9 parts by weight of a blocked isocyanate compound (solid content: 42%, NCO content: 7.5%, manufactured by Nippon Polyurethane Industry Co., Ltd., developed product name: BWD-102); and 73 parts by weight of water;
The isocyanate group of the blocked isocyanate compound was 1.0 molar ratio to the active hydrogen-containing group of the resin.
The obtained coating solution for forming the first intermediate layer is filled in a coating tank, the conductive support is dipped and then pulled up, and the obtained coating film is dried and cured at a temperature of 150 ° C. for 30 minutes to obtain a film thickness of 0.3 μm. The first intermediate layer (blocking layer) was formed.

Next, a second intermediate layer forming coating solution containing inorganic oxide fine particles was prepared in the same manner as in Example 1 except that the following components were used.
Titanium oxide fine particles (average primary particle size: 250 nm, manufactured by Ishihara Sangyo Co., Ltd., product name: CR-EL) as inorganic oxide fine particles 14 parts by weight;
10.7 parts by weight of polyether polyol (solid content: 35%, OH value: 60, manufactured by Nippon Polyurethane Industry Co., Ltd., product name: AQD-473) as resin;
Block isocyanate compound (solid content: 42%, NCO content: 7.5%, manufactured by Nippon Polyurethane Industry Co., Ltd., developed product name: BWD-102) 5.4 parts by weight;
Defoaming agent (polyether foam inhibitor, manufactured by San Nopco, product name: SN deformer 470) 0.06 parts by weight;
Dispersion stabilizer (manufactured by San Nopco, product name: SN Dispersant 2060) 0.035 parts by weight; and water 69 parts by weight;

The isocyanate group (H) of the blocked isocyanate compound is 1.0 molar ratio (H / B) to the active hydrogen-containing group (B) of the resin, and the inorganic oxide fine particles (P) are crosslinked resin (block isocyanate). The weight ratio (P / R) was 7/3 with respect to the total of compound and resin: R).
The obtained coating solution for forming the second intermediate layer was applied onto the previously formed first intermediate layer by the same dip coating method as that for the first intermediate layer, and the obtained coating film was heated at 150 ° C. for 30 minutes. A second intermediate layer having a thickness of 10 μm was formed by drying and curing.
Next, in the same manner as in Example 1, a charge generation layer and a charge transport layer were sequentially formed on the second intermediate layer to produce a photoconductor of Example 17.

Example 18
A photoconductor of Example 18 was produced in the same manner as Example 1 except that the coating solution for forming an intermediate layer was prepared using the following components.
Titanium oxide fine particles (average primary particle size: 35 nm, manufactured by Teika Co., Ltd., product name: MT-500SAS) as inorganic oxide fine particles 12 parts by weight;
Polyvinyl acetal as resin (solid content: 20%, OH value: 960, manufactured by Sekisui Chemical Co., Ltd., product name: KW-1) 4.0 parts by weight;
10.3 parts by weight of a blocked isocyanate compound (solid content: 70%, NCO content: 7.9%, manufactured by Asahi Kasei Chemicals Corporation, developed product name: X1248);
Dispersion stabilizer (manufactured by Sanyo Chemical Industries, product name: Caribon L-400) 0.03 parts by weight; and 74 parts by weight of water;
The isocyanate group (H) of the blocked isocyanate compound is 1.0 molar ratio (H / B) to the active hydrogen-containing group (B) of the resin, and the inorganic oxide fine particles (P) are crosslinked resin (block isocyanate). The weight ratio (P / R) was 6/4 with respect to the sum of compounds and resins: R).

Comparative Example 1
As a charge transport material, instead of the compound (1), the following structural formula (A):
An electrophotographic photosensitive member of Comparative Example 1 was produced in the same manner as in Example 1 except that the compound (A) represented by the formula (A) was used (H / B = 1.0, P / R = 6/4).

Scheme 9
In place of 2,4-dimethylaniline used in Scheme 4 above, di-p-tolylamine (manufactured by Aldrich, product number: 46,108-3, CAS registration number: 620-93-9) was used. The compound (A) can be synthesized by subjecting (v) to an arylamination reaction in the presence of a palladium catalyst, and substituting the amino group of the amine derivative according to the scheme 9 above.

Comparative Example 2
A photoconductor of Comparative Example 2 was produced in the same manner as in Example 1 except that the coating solution for forming an intermediate layer was prepared with the following components (organic solvent system, no curing).
6 parts by weight of titanium oxide fine particles (Ishihara Sangyo Co., Ltd., product name: TTO-D-1) as inorganic oxide fine particles;
Copolymer nylon (product name: Amilan CM8000, manufactured by Toray Industries, Inc.) 4 parts by weight as a resin; and methanol: 50 parts by weight and 1,3-dioxolane: 40 parts by weight as an organic solvent.

Comparative Example 3
An electrophotographic photoreceptor of Comparative Example 3 was produced in the same manner as Comparative Example 2 except that the comparative compound (A) represented by the structural formula (A) was used instead of Compound 1 as the charge transport material. (Organic solvent, no curing).

Comparative Example 4
A photoconductor of Comparative Example 4 was produced in the same manner as in Example 1 except that the intermediate layer forming coating solution was prepared with the following components (aqueous, uncured).
6 parts by weight of titanium oxide fine particles (Ishihara Sangyo Co., Ltd., product name: TTO-D-1) as inorganic oxide fine particles;
As a resin, polyvinyl acetal (solid content: 20%, OH value: 570, manufactured by Sekisui Chemical Co., Ltd., product name: KW-3) 20 parts by weight; and 74 parts by weight of water;

Comparative Example 5
An electrophotographic photoreceptor of Comparative Example 5 was produced in the same manner as Comparative Example 4 except that the comparative compound (A) represented by the structural formula (A) was used instead of Compound 1 as the charge transport material. (Aqueous, no curing).

Comparative Example 6
A photoreceptor of Comparative Example 6 was prepared in the same manner as in Example 1 except that the coating solution for forming the intermediate layer was prepared with the following components (an aqueous, non-block type isocyanate compound (NCO group at 20 ° C. for 20 hours). Use completely)).
Titanium oxide fine particles (Ishihara Sangyo Co., Ltd., product name: TTO-D-1) 12 parts by weight as inorganic oxide fine particles;
As a resin, polyvinyl acetal (solid content: 20%, OH value: 570, manufactured by Sekisui Chemical Co., Ltd., product name: KW-3) 11.2 parts by weight;
5.8 parts by weight of water-dispersed isocyanate (NCO content: 16.5, manufactured by Asahi Kasei Chemicals Corporation, product name: Duranate WB40-100);
0.5 parts by weight of an antifoaming agent (polyether antifoaming agent, manufactured by San Nopco, product name: SN deformer 470); and 71 parts by weight of water;
The isocyanate group (H) of the blocked isocyanate compound is 1.0 molar ratio (H / B) to the active hydrogen-containing group (B) of the resin, and the inorganic oxide fine particles (P) are crosslinked resin (block isocyanate). The weight ratio (P / R) was 6/4 with respect to the sum of compounds and resins: R).

Comparative Example 7
An electrophotographic photoreceptor of Comparative Example 7 was produced in the same manner as Comparative Example 6 except that the comparative compound (A) represented by the structural formula (A) was used instead of Compound 1 as the charge transport material. (Aqueous, non-block type isocyanate compound (NCO group completely decomposes in 20 hours at 20 ° C.) is used; H / B = 1.0, P / R = 6/4).

Evaluation of Examples 1 to 18 and Comparative Examples 1 to 7 (1) Electrical Characteristics and Environmental Stability of the Photoreceptor The photoreceptors obtained in Examples 1 to 18 and Comparative Examples 1 to 7 were used in the image forming process. Mounted on a commercially available digital copying machine (manufactured by Sharp Corporation, model: MX-3100FG) provided with a surface potentiometer (manufactured by Gentec Corporation, model: CATE751) so that the surface potential of each photosensor can be measured. The body's electrical properties and environmental stability were evaluated.
First, in an N / N environment at a temperature of 22 ° C. and a relative humidity of 65%, the surface potential of the photoreceptor immediately after the charging operation by the charger was measured as a charging potential V0 (V). Further, the surface potential of the photoreceptor immediately after being exposed by laser light (wavelength: 780 nm) was measured as a residual potential VL (V) in an N / N environment.

  Further, the residual potential VL (V) is measured in an N / H environment at a temperature of 25 ° C. and a relative humidity of 85% and in an N / L environment at a temperature of 25 ° C. and a relative humidity of 5% in the same manner as in the N / N environment. These differences were obtained as potential fluctuation ΔVL (V). That is, it can be evaluated that the smaller the potential fluctuation ΔVL (V), the better the environmental stability (environmental characteristics).

Next, in a N / N environment at a temperature of 22 ° C. and a relative humidity of 65%, a test image having a predetermined pattern (a character test chart defined in ISO 19752) was continuously copied on 100,000 sheets of recording paper, In the same manner as in the initial stage, the surface potential of the photoconductor immediately after the charging operation is measured as a charging potential V0 (V), and the surface potential of the photoconductor after exposure is measured as a residual potential VL (V). It was determined as a potential fluctuation ΔVLS (V) which is an index of fatigue characteristics.
Further, after the intermediate layer forming coating solutions of Examples 1 to 18 and Comparative Examples 1 to 7 were stored at room temperature and humidity for 3 months, photoconductors were prepared in the same manner, and a residual potential was obtained in an N / N environment. The difference between the value when VL [V] was measured and the value of the initial residual potential VL was obtained as the potential fluctuation ΔV _LP .
In addition to the N / N environment, the residual potential VL (V) in an L / L environment at a temperature of 5 ° C. and a relative humidity of 10% was also measured.

(2) Curing degree 0.5 g of the intermediate layer-forming coating solution prepared in Examples 1 to 19 and Comparative Examples 1 to 7 was applied to the surface of a glass plate having dimensions of 50 mm × 50 mm × thickness 2 mm by the wire bar method. The sample was uniformly applied, and the resulting coating film was dried and cured at a temperature of 150 ° C. for 30 minutes to obtain a sample.
The obtained samples were immersed in acetone at a temperature of 20 ° C. for 1 day with stirring at a rotation speed of 30 rpm, and the degree of cure (%) was determined from the weight difference between the initial weight before immersion and the weight after immersion from the following formula. It was.
Curing degree (%) = (1− (initial weight−weight after immersion) / (initial weight)) × 100
Further, the degree of cure (%) was determined in the same manner as above except that the obtained sample was immersed in acetone for 3 months.
The degree of cure (%) after 3 months was determined in the same manner as above.

(3) Image quality Evaluation of the quality of the image formed using a photoconductor was performed as follows.
A commercially available laser beam printer (manufactured by Sharp Corporation: MX-3100FG) using a laser as an exposure light source can be normally developed, and the exposure light amount to the photosensitive member and the rotational peripheral speed of the photosensitive member can be changed. Each of the photoreceptors produced in Examples 1 to 19 and Comparative Examples 1 to 7 was mounted on the apparatus obtained by remodeling as described above, and an image was formed on the recording paper. At this time, by changing the rotational peripheral speed of the photoconductor, the time from the start of exposure to the end of development on the photoconductor is set to 50 milliseconds (50 msec), 90 milliseconds (msec), or 130 milliseconds (msec). Adjustments were made and images were formed at each set time. The obtained image was visually observed to evaluate the quality of the image.

(4) Evaluation of printing durability The image exposure light source of a digital copying machine (manufactured by Sharp Corporation: AR-451S) with a process speed of 225 mm / sec was replaced with a 405 nm semiconductor laser (image writing by a polygon mirror). Each electrophotographic photosensitive member was mounted. After forming 50,000 images, the film thickness d1 of the photosensitive layer is measured, and the difference between this value and the film thickness d0 of the photosensitive layer at the time of production is obtained as a film reduction amount Δd (= d0−d1) An evaluation index for printing durability was used.
These evaluation results are shown in the following table.
(5) Comprehensive evaluation Comprehensive evaluation is performed for the evaluation items (1) to (4) above, and “G”: good (good), “B”: bad (bad), and “VB” for each example. : Shown with a very bad evaluation index.

As shown in Table 1, the photoreceptors of the present invention (Examples 1 to 12, 17 and 18) are more conjugated than the compounds (1) to (6) used in the present invention as in Comparative Example 1. It can be seen that the half-exposure amount (E1 / 2) is smaller than that of a photoreceptor using a triphenylamine compound having a narrow spread and a slow charge mobility as a charge transporting material, and the sensitivity is excellent.
Further, it was confirmed that the photoconductors of Examples 1 to 18 were superior to the photoconductor of Comparative Example 1 in printing durability.

Furthermore, in contrast to the organic solvent-based comparative example 2 using a polyamide-based binder resin that is often used in current photoreceptors, despite the fact that the solvent of the coating solution is water, the photoreceptors of the examples are In addition, it was confirmed that the performance was equivalent or better in terms of electrical characteristics, environmental stability, fatigue characteristics, and coating liquid stability.
As in Comparative Example 3 in the same system, a triphenylamine compound having a narrow conjugated system spread and slow charge mobility compared to the compounds (1) to (6) used in the present invention is used as a charge transport material. The photoconductor used has low sensitivity in the L / L environment as in Comparative Example 1, and it can be confirmed that the printing durability is inferior to the photoconductors of the present invention (Examples 1 to 12, 17 and 18). It was.

Moreover, the photoreceptor by Example 10 using the coating liquid for intermediate | middle layer formation containing an antifoamer (prescription other than an antifoamer is the same) implementation using the coating liquid for intermediate | middle layer formation which does not contain an antifoamer. Compared to the photoreceptor of Example 18, it was found that the electrical characteristics and pot life were slightly better.
This is presumably because the coating liquid for forming an intermediate layer containing an antifoaming agent decreased the foaming at the time of dispersion and increased the dispersibility, thereby reducing the remaining coarse particles in the coating liquid for forming an intermediate layer.
Therefore, it has been found that when a dispersion stabilizer and an antifoaming agent are added, a coating agent having a better pot life is produced.

In addition, a photoconductor using an intermediate layer forming coating solution containing a dispersion stabilizer (Example 8: the same formulation other than the dispersion stabilizer) is a photosensitive material using an intermediate layer forming coating solution not containing a dispersion stabilizer. As compared with the body (Example 7), it was found that the electrical characteristics and pot life were slightly superior.
This is considered to be because the dispersibility of the particles during long-term storage is excellent by including a dispersion stabilizer in the coating liquid.
Further, the examples using titanium oxide or zinc oxide fine particles as the inorganic oxide fine particles are more charged than the case of using fine particles other than titanium oxide or zinc oxide as in Examples 13 and 14, and the charging characteristics and fatigue characteristics of the photoreceptor. Was observed to be excellent.

Further, it was found that when the amount of the curing agent is small (the number of NCO groups is small) as in Example 15, the degree of curing becomes low, so that the ratio of hydrophilic groups in the film increases and the environmental stability deteriorates. .
On the contrary, when the amount of the curing agent was increased as in Example 16, the environmental characteristics were not deteriorated so much, but the fatigue characteristics and the storage stability of the coating liquid were deteriorated. This is probably because excess isocyanate groups reacted with moisture to produce impurities that affect electrical properties.
Moreover, when the water-based binder resin which is not hardened like Comparative examples 4 and 5 was used, it has also confirmed that an environmental characteristic deteriorated very much.

In the same system, a photoconductor using a charge transport material and a triphenylamine compound having a slow charge mobility, which is not the subject of the present invention in Comparative Example 5, has a residual potential in an L / L environment as in Comparative Example 1. The sensitivity was poor, and it was confirmed that the printing durability was improved as compared with the photoreceptors of the present invention (Examples 1-11, 17, 17).
It can also be seen that when a water-dispersed isocyanate compound that is not a block type is used as the curing agent as in Comparative Examples 6 and 7, the storage stability of the coating liquid is extremely poor. This is because the NCO group of the isocyanate compound is completely decomposed at 20 ° C. for 20 hours according to the manufacturer's data. For this reason, the characteristics of the photoconductor produced immediately after the coating solution adjustment shows a certain level of performance. However, since the curing agent decomposed in about one day, no curing occurred in the coating solution after three months, and the decomposition of the isocyanate group occurred. This is thought to be due to the deterioration of electrical characteristics due to the composition.

  In the same system, the photoconductor using the charge transport material having a low charge mobility of Comparative Example 7 has a low residual potential and sensitivity in the L / L environment as in Comparative Example 1, and the photoconductor of the present invention. It was confirmed that the printing durability was inferior to those of Examples 1 to 14, 17 and 18.

Further, since the photosensitive layer contains a triphenylamine compound having a high charge mobility and excellent printing durability represented by the general formula (I), it exhibits high responsiveness even in a low-temperature and low-humidity environment, and printing durability. An electrophotographic photoreceptor excellent in the above can be obtained.
Therefore, even when the electrophotographic photosensitive member is miniaturized and used in a high-speed electrophotographic process, high-quality images can be provided over a long period of time in various environments such as a low temperature and low humidity environment. By using such an electrophotographic photosensitive member, it is possible to provide a stable and high-quality image even in various environments such as a small size, a high image forming speed, and a low temperature and low humidity environment. A high image forming apparatus can be realized.

1 conductive support 2 intermediate layer (undercoat layer)
DESCRIPTION OF SYMBOLS 3 Charge generation layer 4 Charge transport layer 5 Laminated type photosensitive layer 5 'Single layer type photosensitive layer 20 Image forming apparatus 21 Electrophotographic photosensitive member 22 Rotating axis 23, 29 Arrow 24 Charging means (charger)
24a Charging roller 24b Bias power supply 25 Developing means (developer)
25a Developing roller 25b Casing 26 Transfer means (transfer device)
27 Cleaning means (cleaner)
27a Cleaning blade 27b Recovery casing 28 Exposure means 28a Exposure light 30 Transfer paper 31 Fixing means (fixing device)
31a Heating roller 31b Pressure roller

Claims (12)

An intermediate layer on a conductive support; a laminated photosensitive layer or reverse laminated photosensitive layer in which a charge generating layer containing a charge generating material and a charge transporting layer containing a charge transporting material are laminated in this order; A single-layer type photosensitive layer containing a charge transport material;
The intermediate layer includes at least a blocked isocyanate compound and a binder resin having an active hydrogen-containing group capable of reacting with an isocyanate group,
The photosensitive layer has the following general formula (I) as a charge transport material:
In a triphenylamine compound in to that electronic photoreceptors containing indicated,
The triphenylamine compound is
R is a methyl group, a to d and g are 1, e and f are 0, R _{1 to} R ₄ are 4-methyl groups, and R ₇ is a 2-methyl group. Formula (1):
A compound (1) represented by:
The R is a methyl group, the a to f are 0, the g is 1, the R ₇ is a 2-methyl group, and the formula (2):
A compound (2) represented by:
The R is a 2,2-diphenylethenyl group, the a to f are 0, the g is 1, the R ₇ is a 2-methyl group, and the formula (3):
A compound (3) represented by:
R is a 2,2-diphenylethenyl group, a to g are 0, and the formula (4):
A compound (4) represented by:
The R is a 2,2-di (p-methyl) phenylethenyl group, the a to d are 1, the e to g are 0, and the R _{1 to} R ₄ are 4-methyl groups. Yes, formula (5):
Or a compound (5) represented by:
The R is a methyl group, the a to d are 1, the e to g are 0, the R _{1 to} R ₄ are 4-methyl groups, and the formula (6):
An electrophotographic photosensitive member which is a compound (6) represented by the formula: The photoreceptor according to claim 1, wherein the binder resin has two or more active hydrogen-containing groups. The active hydrogen-containing group is, photosensitive member according to claim 1 or 2 is a hydroxyl group or an amide group. Photosensitive member according to the isocyanate group, any one of claims 1 to 3 present in the blocked isocyanate compound in a molar ratio of 0.5 to 1.5 relative to the active hydrogen-containing group. The photoreceptor according to any one of claims 1 to 4 , wherein the blocked isocyanate compound has a structure in which hexamethylene diisocyanate or isophorone diisocyanate is blocked with an oxime or lactam blocking agent. It said binder resin is a polyether polyol resin, polyester polyol resin, polyacryl polyol resins, polyvinyl alcohol resins, polyvinyl acetal resins, either one of claims 1 to 5 which is selected from cellulose and polyamide resin 1 The photoreceptor described in 1. Photosensitive member according to the intermediate layer, any one of claims 1-5, further comprising an inorganic oxide fine particles. The intermediate layer, the photosensitive member according to any one of claims 1-7 comprising titanium oxide or zinc oxide fine particles as the inorganic oxide fine particles. The intermediate layer, the photosensitive member according to any one of claims 1-8 as the inorganic oxide fine particles containing fine particles having an average primary particle size 20 to 500 nm. The intermediate layer is coated with a coating solution for forming an intermediate layer in which at least a blocked isocyanate compound and a binder resin having an active hydrogen-containing group capable of reacting with an isocyanate group are dissolved or dispersed in an aqueous medium, and then thermally cured. The method for producing an electrophotographic photosensitive member according to any one of claims 1 to 9 , which is obtained. The manufacturing method according to claim 10 , wherein the intermediate layer forming coating solution further contains an antifoaming agent. An electrophotographic photosensitive member according to any one of claims 1 to 9 , a charging means for charging the electrophotographic photosensitive member, and an electrostatic latent image formed by exposing the charged electrophotographic photosensitive member. An exposure means for forming the toner, a developing means for developing the electrostatic latent image to form a toner image, a transfer means for transferring the toner image onto the recording material, and the transferred toner image on the recording material. At least a fixing unit that forms an image by fixing the toner onto the electrophotographic photosensitive member, a cleaning unit that removes and collects toner remaining on the electrophotographic photosensitive member, and a neutralizing unit that neutralizes surface charge remaining on the electrophotographic photosensitive member. An image forming apparatus.