JP2010249871A - Electrophotographic photoreceptor and image forming apparatus having the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coating liquid for a charge generating layer of a photoreceptor having an organic photosensitive layer that uses water with the smallest environmental load as a solvent and is excellent in temporal stability of liquid physical property also in production; to provide the photoreceptor having a charge generating layer formed using it, high repetition characteristics, and high environmental stability; and to provide an image forming apparatus having the photoreceptor. <P>SOLUTION: The electrophotographic photoreceptor is formed by stacking at least the charge generating layer and a charge transport layer on an electroconductive support. The charge generating layer is formed by thermosetting coating liquid for the charge generating layer containing a charge generating material, block isocyanate compound, resin having an active hydrogen-containing group capable of reacting with an isocyanate group in the block isocyanate compound, and an aqueous medium. The charge generating material is oxo titanium phthalocyanine having a crystal structure. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to an electrophotographic photosensitive member provided with a charge generation layer formed of a coating solution for a charge generation layer using water containing oxotitanium phthalocyanine having a crystal structure as a charge generation material, which has extremely high sensitivity. The present invention relates to 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. A photosensitive layer containing a photoconductive material is laminated on the surface, and an inorganic photoconductive material such as selenium has been conventionally used as the photoconductive material.
On the other hand, the organic photoconductive material is slightly inferior in terms of sensitivity, durability and stability to the environment as compared with the inorganic photoconductive material, but from the viewpoint of toxicity, manufacturing cost, freedom of material design, etc. In recent years, it has been widely used.

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, and the performance is also improved. It is improving.
At present, the mainstream is a configuration in which an intermediate layer, a stacked type (functional separation type) photosensitive layer in which a charge generation layer and a charge transport layer are stacked in this order are stacked in this order on a conductive support. It has become.

  When coating an organic material on a conductive support, constituent materials soluble in a solvent such as a resin can be dissolved in a solvent and applied, but constituent materials that are generally insoluble in a solvent such as a pigment are Since it cannot be applied as it is, a dispersion method is required. Here, “dispersion” means that a pigment or the like is finely divided in a solvent to form a suspended state without a precipitate, and “dispersion stability” means that the particle diameter is uniform and long in the solvent. Means stable storage over time.

  When the dispersibility of pigments and the like is deteriorated in the dispersion, the coated surface of the formed coating film is rough, which causes image defects such as pinholes and density unevenness of the photoreceptor. In addition, if coarse particles with poor dispersion exist in the dispersion, it may cause deterioration of repeated stability of electric characteristics and fogging such as black spots on a copy image. Furthermore, if the dispersed particles settle out over time and the concentration of the dispersion is not uniform, a uniform photosensitive layer cannot be formed, resulting in uneven image density, and the coating amount increases due to thickening of the dispersion. It may cause fluctuations in productivity.

  As a method for obtaining a good pigment dispersion, the molecular structure of a part of the pigment is changed, or the aggregation state is controlled by mixing pigments of different molecular structures. The pigment surface is soluble in a solvent. There is a method of adsorbing resin. However, these methods have a problem that the electrophotographic properties of the pigment itself, that is, the sensitivity and the repetitive characteristics change, and the basic purpose of the pigment cannot achieve its initial purpose as a photoreceptor.

Thus, various attempts have been made so far to improve such problems.
For example, JP-A-8-29991 (Patent Document 1) and JP-A-2000-330305 (Patent Document 2) disclose a method using a specific organic solvent as a dispersion solvent, JP-A-9-304950 (Patent Document 2). Document 3) discloses a method of dispersing a heat-treated binder in a solvent, and JP-A-7-152167 (Patent Document 4) discloses a method of diluting a binder with a solvent that does not dissolve at the end of the pigment dispersion step. Has been.
The optimization of these dispersion solvents and the improvement of binders have greatly contributed to the acquisition of high dispersibility and high electrophotographic characteristics, but since both use petroleum-based solvents as solvents, they have recently been rapidly closed up. In order to reduce environmental loads such as reduction of volatile organic compounds (VOC) and CO _2, reduction of these petroleum solvents is an urgent task.

On the other hand, for the binder, a highly dispersible resin such as polyvinyl butyral resin has been developed and widely used. However, since these resins have many polar groups such as hydroxyl groups for improving dispersibility, they are inferior in moisture resistance. In particular, in a high-temperature and high-humidity environment, carrier injection increases due to the influence of humidity, and black It causes the deterioration of image quality due to image defects such as.
Therefore, as a method for improving the influence of such humidity, JP-A-8-160643 (Patent Document 5) discloses a method of thermosetting the charge generation layer using a melamine resin. However, melamine resin is said to be one of the causative substances of sick house syndrome at the time of resin production, and a large amount of formaldehyde currently listed as a target substance in 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 clearly expensive to introduce the facility.

On the other hand, a highly sensitive oxotitanium phthalocyanine has recently been found as a charge generating material used in the photosensitive layer, and oxotitanium phthalocyanine having a crystalline form (also referred to as “crystalline oxotitanium phthalocyanine”) is used for light in a long wavelength range. Have been reported to exhibit particularly high sensitivity.
Crystalline oxotitanium phthalocyanine is known to be classified into a number of crystal types based on the difference in diffraction angle of the X-ray diffraction spectrum (for example, Moto Miyazaki, “Digital Imaging Technology-Photoconductor”, Electrophotographic Society of Japan). Journal, 1993, Vol. 32, No. 3, p. 282-289).
Examples of such crystal types include α type, A type, C type, Y type, M type, M-α type, I type, Phase I type, and Phase II type.

  Further, in the structural analysis of crystalline oxotitanium phthalocyanine, it has been found from its lattice constant that Phase II type belongs to the triclinic system, and Phase I type and C type belong to the monoclinic system. When the above crystal types are analyzed from these known lattice constants, it can be seen that the A type and the I type belong to the Phase I type, the α and B types belong to the Phase II type, and the M type belongs to the C type.

  As crystalline oxotitanium phthalocyanine, for example, Japanese Patent Publication No. 7-91486 (Patent Document 6) shows a maximum diffraction peak at a Bragg angle 2θ (2θ ± 0.2 °) of 27.3 ° in an X-ray diffraction spectrum. , 7.4 °, 9.7 °, and crystalline oxotitanium phthalocyanine having diffraction peaks at 24.2 °, Japanese Patent No. 2700859 (Patent Document 7), Bragg angle 2θ (2θ ± 0.2 °) Crystalline oxotitanium phthalocyanine having major diffraction peaks at 9.5 °, 9.7 °, 11.7 °, 15.0 °, 23.5 °, 24.1 ° and 27.3 °, Japanese Patent No. 128973 (Patent Document 8) discloses crystalline oxotitania having major diffraction peaks at Bragg angles 2θ (2θ ± 0.2 °) of 9.0 °, 14.2 °, 23.9 ° and 27.1 °. Photoreceptors using phthalocyanine is described.

  Japanese Patent No. 3569422 (Patent Document 9) discloses an X-ray diffraction spectrum having a maximum diffraction peak at a Bragg angle 2θ (2θ ± 0.2 °) of 9.4 °, at least 7.3 °, Diffraction peaks are shown at 9.7 ° and 27.3 °, and 9.4 ° and 9.7 ° have distinct branching peaks, both of which are larger than the diffraction peak at 27.3 °. Crystalline oxotitanium phthalocyanine is described, and a photoreceptor using it as a charge generation material is particularly sensitive to light in a long wavelength region, and is described to have good stability of characteristics in repeated use. Yes.

JP-A-8-29991 JP 2000-330305 A JP-A-9-304950 JP-A-7-152167 JP-A-8-160643 Japanese Examined Patent Publication No. 7-91486 Japanese Patent No. 2700859 Japanese Patent Laid-Open No. 3-128973 Japanese Patent No. 3569422

Moto Miyazaki, “Digital Imaging Technology-Photoconductor”, Journal of Electrophotographic Society, 1993, Vol. 32, No. 3, p. 282-289

However, a photoconductor using oxotitanium phthalocyanine having a crystal structure as a charge generation material is humidity-dependent, and is susceptible to fluctuations in sensitivity due to environmental dependence, and image defects such as black spots appear in an actual image. There is a problem.
It has been reported that oxotitanium phthalocyanine having a crystal structure changes its charge generation efficiency by coexistence with water. Although its clear mechanism has not been elucidated, oxotitanium phthalocyanine having a crystal structure is thought to generate charges due to the interaction with water, so the charge generation efficiency varies depending on the amount of water around the crystal. Presumed.

  The present invention uses a coating solution for a charge generation layer of a photoreceptor having an organic photosensitive layer, which uses water having the smallest environmental load as a solvent and has excellent liquid property over time in production. It is an object of the present invention to provide a photoconductor having a repeated charge generation layer and excellent in repetitive characteristics and environmental stability, and an image forming apparatus including the same.

  As a result of intensive studies to solve the above problems, the present inventors have found that a charge generating material, a blocked isocyanate compound, and a resin having an active hydrogen-containing group capable of reacting with an isocyanate group in the blocked isocyanate compound, In addition, the coating solution for the charge generation layer containing an aqueous medium, that is, water that has the lowest environmental impact and does not cause VOC and has no danger of fire is used as a solvent. A photoconductor with excellent repetitive characteristics and environmental stability, which is formed using a coating solution for a charge generation layer of a photoconductor, has extremely low variation in water concentration due to environmental fluctuations, and has a high moisture resistance due to a highly moisture-resistant charge generation layer. The present inventors have found that an image forming apparatus equipped with the same can be provided, and have completed the present invention.

  Thus, according to the present invention, at least a charge generation layer and a charge transport layer are laminated on a conductive support, and the charge generation layer comprises a charge generation material, a blocked isocyanate compound, and the blocked isocyanate compound. A layer formed by thermal curing from a coating solution for a charge generation layer containing a resin having an active hydrogen-containing group capable of reacting with an isocyanate group therein and an aqueous medium, and the charge generation material has a crystal structure There is provided a photoconductor characterized by being an oxotitanium phthalocyanine having the following formula.

  According to the invention, the photosensitive member is formed by exposure, the charging unit for charging the photosensitive member, the exposure unit for exposing the charged photosensitive member to form an electrostatic latent image, and exposure. Developing means for developing the electrostatic latent image to form a toner image, transfer means for transferring the toner image formed by development onto a recording material, and fixing the transferred toner image on 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 photoconductor, and a static elimination unit that neutralizes surface charge remaining on the photoconductor. An apparatus is provided.

  According to the present invention, water having the least environmental load is used as a solvent, and the coating property solution for a charge generation layer of a photoreceptor having an organic photosensitive layer, which is excellent in liquid property over time in production, and using the same It is possible to provide a photoconductor having a charge generation layer formed in this manner and excellent in repetitive characteristics and environmental stability, and an image forming apparatus including the same.

That is, the photoreceptor of the present invention contains oxotitanium phthalocyanine having a crystal structure having high charge generation ability and high charge injection efficiency as a charge generation material, and can generate a large amount of charge by light absorption. A highly sensitive photoreceptor can be realized.
Further, since the photoreceptor of the present invention uses an aqueous medium as a solvent for the charge generation layer coating solution, a resin having a high affinity for water must be used, but the resin is thermoset with an isocyanate compound, Since the hydrophilic functional group in the resin is reduced and the coating film is densified as a cured film, high moisture resistance is obtained for the photoreceptor, and excellent environmental stability can be realized.
That is, according to the present invention, the use of an aqueous medium as the solvent for the charge generation layer coating solution eliminates the problem of air pollution due to VOC in the production process, as well as conventional petroleum-based solvents. Since there is no problem of CO ₂ emission, it contributes to the prevention of global warming, and furthermore, there is no risk of fire, so the manufacturing system can be simplified and the manufacturing cost can be reduced.

The isocyanate group of the isocyanate compound reacts easily with water. However, in the present invention, since a blocked isocyanate compound in which an isocyanate group is protected with a stable protective group in water is used, a pot life equivalent to or higher than that of a conventional organic solvent-based coating liquid can be realized.
In the present invention, 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. It is possible to realize excellent environmental characteristics as a photoreceptor.

FIG. 3 is a schematic cross-sectional view illustrating a configuration of a main part of the photoconductor of the present invention. FIG. 3 is a schematic cross-sectional view illustrating a configuration of a main part of the photoconductor of the present invention. It is a figure which shows the X-ray-diffraction spectrum of the crystalline oxotitanium phthalocyanine of this invention. It is a figure which shows the X-ray-diffraction spectrum of the crystalline oxotitanium phthalocyanine of this invention. It is a figure which shows the X-ray-diffraction spectrum of the crystalline oxotitanium phthalocyanine of this invention. 1 is a schematic side view illustrating a configuration of an image forming apparatus of the present invention.

  The photoreceptor of the present invention is formed by laminating at least a charge generation layer and a charge transport layer on a conductive support, and the charge generation layer comprises a charge generation material, a blocked isocyanate compound, and the blocked isocyanate compound. A layer formed by thermal curing from a coating solution for charge generation layer containing a resin having an active hydrogen-containing group capable of reacting with an isocyanate group and an aqueous medium, and the charge generation material has a crystalline structure. It is characterized by having an oxotitanium phthalocyanine.

The photoreceptor of the present invention will be specifically described with reference to the drawings.
1 and 2 are schematic cross-sectional views showing the structure of the main part of the photoreceptor of the present invention.
FIG. 1 is a schematic cross-sectional view showing the configuration of the main part of a laminated photoreceptor having a laminated photosensitive layer (also referred to as “function-separated photosensitive layer”) in which a charge generation layer and a charge transport layer are laminated in this order. It is.
FIG. 2 is a schematic cross-sectional view showing the configuration of the main part of a laminated photoreceptor having an inverted two-layer laminated photosensitive layer in which a charge transport layer and a charge generation layer are laminated in this order.
1 and 2 may be any, but the multilayer photosensitive layer of FIG. 1 is preferred.
The photoreceptor of the present invention preferably has an intermediate layer between the conductive support and the laminated photosensitive layer as in the photoreceptors of FIGS.

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.
The charge generation layer coating solution, which is a feature of the present invention, oxotitanium phthalocyanine having a crystal structure included therein, and other components will be described in detail in this order.

[Coating liquid for charge generation layer]
The charge generation layer coating liquid of the present invention contains a charge generation material, 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 an aqueous medium.

  A blocked isocyanate compound is a compound in which an isocyanate group of an aqueous isocyanate compound that can be dissolved or dispersed in water is protected with a blocking agent such as oxime, and contains active hydrogen that can react with an isocyanate group such as a hydroxyl group or an amide group by heating. An addition reaction is initiated with the resin having a group, the blocking agent is removed, and the crosslinking reaction proceeds. That is, the blocked isocyanate compound becomes a resin crosslinking agent.

  The aqueous isocyanate compound is a form in which an organic polyisocyanate having a plurality of isocyanate groups in one molecule is modified with various hydrophilic groups such as polyethylene oxide, a carboxyl group or a sulfonic acid group, or dissolved or made into a self-emulsifying type, or It is a compound in a form 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 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 diisocyanate-based organic polyisocyanates such as hexamethylene diisocyanate and isophorone diisocyanate tend to have an affinity for water, so that they can be easily dissolved and dispersed in water and have a crosslinking density. It is particularly preferable because it is easy to increase the value.

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 Oxime compounds such as shim, methyl isobutyl ketoxime, cyclohexanone oxime; and amine compounds such as diphenylaniline, aniline, carbazole, ethyleneimine, and polyethyleneimine. These blocking agents may be used alone or in combination of two or more. Can be used in combination.
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.

Further, 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 .;
Nippon Polyurethane Industry Co., Ltd., developed product name: BWD-102
Asahi Kasei Chemicals Corporation, developed product name: X1238, X1248 and X1258
Etc.

The active hydrogen-containing group in the resin having an active hydrogen-containing group 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, in order to form a crosslinked structure with the blocked isocyanate which is a curing agent, it has at least two equivalents of at least two isocyanate groups in the blocked isocyanate compound, that is, has at least two hydroxyl groups or amide groups (has only one functional group). If not, a polyol resin or a polyamide resin is preferable because it does not have a crosslinked structure but has a high molecular weight. In addition, by controlling the structure of these polyol resins and polyamide resins, they can be dispersed and dissolved in water satisfactorily, and these resins have high adhesion and are due to poor contact with the lower layer when used as a photoreceptor. Image defects can also be effectively prevented.

As these polyol resin and polyamide resin, for example,
Product name: AQD-457 and AQD-473, manufactured by Asahi Glass Co., Ltd., product name: Exenol 420 and 720, manufactured by Sanyo Chemical Industries, Ltd., product name: Sannix GP-400, GP-700 And polyether polyol 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
DIC Corporation product name: Burnock WE-300, WE-304 and WE-306, Asia Industry Co., Ltd., product name: WAP-473-FD and WAP-548, Nuplex Industries Ltd. product name: SETAQUA6514 Such as polyacryl polyol 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 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 present in the blocked isocyanate compound in a molar ratio of 0.5 or more and 1.5 or less with respect to the active hydrogen-containing group (B) of the resin. 1.2 or less is more preferable, and 0.6 or more and 1.1 or less is more preferable.
When the molar ratio (H / B) is less than 0.5 or exceeds 1.5, a large number of unreacted functional groups remain, the crosslinking density is lowered, and the photosensitive layer having the formed intermediate layer is formed. The environmental stability of the body may be reduced.

The compounding ratio of the charge generating material and the cross-linked resin (total of blocked isocyanate compound and resin: R) is not particularly limited, but the charge generating material is usually about 10 to 90% by weight.
If the charge generating 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 the portion to be erased by exposure are reduced, and there is a risk that image defects, particularly an image fogging called black spots in which toner adheres to a white background and minute black spots are formed.

The charge generation layer coating solution may further contain an antifoaming agent.
The antifoaming agent is intended to suppress foam by adding a very small amount to the charge generation layer coating solution.
When water is used as a solvent as in the charge generation layer coating liquid 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.
Examples of antifoaming agents are San Nopco Corporation, product names: SN deformers 444, 470, 485, PC (polyether type), SN deformers 1311, 1316 (silicone type), SN deformers 777, 328, 480, 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: silicone such as DK Q1-1247 -Emulsions are listed.

The antifoaming agent is preferably 0.05 to 0.0005 parts by weight with respect to 1 part by weight of the crosslinked resin (total of blocked isocyanate compound and resin: R).
If the defoamer exceeds 0.05 parts by weight, the electrical characteristics of the photoreceptor may be deteriorated, and if it is less than 0.0005 parts by weight, an effective foam breaking effect may not be obtained.

The coating solution for a charge generation 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.

The charge generation layer coating liquid of the present invention is obtained by dissolving or dispersing a charge generation material, a blocked isocyanate compound, a resin having an active hydrogen-containing group capable of reacting with an isocyanate group, and an optional additive in an aqueous medium. Can be prepared.
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 constituents of the coating solution for the charge generation layer in an aqueous medium, a general dispersing machine such as a paint shaker, a ball mill, a sand mill, a general ball mill, a sand mill, an attritor, a vibration mill, an ultrasonic dispersing machine, etc. An appropriate crusher may be used.

In order to stabilize the dispersion, a dispersion stabilizer (also referred to as “dispersing agent”) may be added to the charge generation layer coating solution.
Examples of the dispersant include polycarboxylic acid, naphthalene sulfonic acid, phosphate, polyphosphoric acid, special cation, and surfactant. Among these, in terms of dispersion stabilization effect Polycarboxylic acid and naphthalene sulfonic acid are particularly preferred.

  Examples of the dispersant include, for example, Sanyo Kasei Co., Ltd., product names: Caribon L-400 (polycarboxylic acid type), Elestat AP-130 (polycarboxylic acid type), Sunspearl PS-8 (polycarboxylic acid type), PDN-173 (polycarboxylic acid type), Ionet S-85 (surfactant type) and New Pole PE-61 (surfactant type), manufactured by San Nopco, product name: Roma PWA-40 (naphthalene sulfonic acid type) ), Nobcosant RFA (polycarboxylic acid type), SN Dispersant 2060 (polyphosphoric acid type), 5020 (polycarboxylic acid type), 5029 (polycarboxylic acid type), 5468 (polycarboxylic acid type), 7347C (special cation type) ) And SN wet P (surfactant system), manufactured by Nissin Chemical Industry Co., Ltd., product name: Surfynol 10 E (surfactant type) and Olphine PD-003 (surfactant type), manufactured by Kao Corporation, product names: Poise 520 (polycarboxylic acid type), 530 (polycarboxylic acid type), homogenol L 100 (polycarboxylic acid) Acid), demole NL (naphthalene sulfonic acid), demole RN-L (naphthalene sulfonic acid), manufactured by Daiichi Kogyo Seiyaku Co., Ltd., Charol AN-103P (polycarboxylic acid), AH-144P (polycarboxylic acid) System), DISCOAT N-14, manufactured by Toho Chemical Co., Ltd., product name: dibrozin A-100 (polycarboxylic acid type), neoscope SCT-30 (polycarboxylic acid type), and the like.

The amount of the dispersant added is preferably 0.02 to 0.0005 parts by weight with respect to 1 part by weight of the charge generation material.
When the dispersant exceeds 0.02 parts by weight, the electrical characteristics of the photoreceptor may be deteriorated. When the dispersant is less than 0.0005 parts by weight, an effective dispersion stabilizing effect may not be obtained.

[Oxotitanium phthalocyanine with crystal structure]
As described later, oxotitanium phthalocyanine having a crystal structure can be obtained by pulverizing oxotitanium phthalocyanine in an organic solvent.
Oxotitanium phthalocyanine has the formula (A):

(Wherein X ¹ , X ² , X ³ and X ⁴ are the same or different and are a halogen atom, an alkyl group or an alkoxy group, and r, s, y and z are the same or different and represent 0-4. Is an integer)
Indicated by

The halogen atom of X ^1, X ^2, X ³ and X ⁴ in formula (A), fluorine, chlorine, bromine and iodine atoms.
Examples of the alkyl group represented by X ¹ , X ² , X ³ and X ⁴ include alkyl groups having 1 to 4 carbon atoms such as methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group and t-butyl group. Is mentioned.
Examples of the alkoxy group for X ¹ , X ² , X ³ and X ⁴ include alkoxy having 1 to 4 carbon atoms such as methoxy group, ethoxy group, propoxy group, isopropoxy group, butoxy group, isobutoxy group and t-butoxy group. Groups.

  The oxotitanium phthalocyanine compound represented by the formula (A) is produced by a known production method such as, for example, the method described in Phthalcocyanine Compounds, Reinhold Publishing Corp., New York, 1963 by Moser, Frank H and Arthur L. Thomas. can do.

  For example, among the oxotitanium phthalocyanine compounds represented by the formula (A), in the case of an unsubstituted oxotitanium phthalocyanine in which r, s, y, and z are 0, are phthalonitrile and titanium tetrachloride heated and melted? Alternatively, it can be obtained by synthesizing dichlorotitanium phthalocyanine by heating in a suitable solvent such as α-chloronaphthalene and then hydrolyzing with base or water.

  Alternatively, oxotitanium phthalocyanine can be produced by reacting isoindoline with titanium tetraalkoxide such as tetrabutoxytitanium in a suitable solvent such as N-methylpyrrolidone.

Specifically, as the oxotitanium phthalocyanine having a crystal structure, at least a Bragg angle (2θ ± 0.2 °) 27.1 to 27.3 ° in an X-ray diffraction spectrum using CuKα ray (1.541Å). Crystalline oxotitanium phthalocyanine exhibiting a diffraction peak is preferred.
As such a crystalline oxotitanium phthalocyanine,
Commonly known Y-type, M-type and I-type oxotitanium phthalocyanines,
As shown in FIG. 3, the maximum diffraction peak is shown at a Bragg angle 2θ (2θ ± 0.2 °) of 9.4 °, and the diffraction peaks are shown at least at 7.3 °, 9.7 °, and 27.3 °, And crystalline oxotitanium phthalocyanine (Crystal 1), which has distinct branched peaks at 9.4 ° and 9.7 °, and shows a diffraction peak larger than the diffraction peak at 27.3 °.
As shown in FIG. 4, the Bragg angle 2θ (2θ ± 0.2 °) 9.5 °, 9.7 °, 11.7 °, 15.0 °, 23.5 °, 24.1 ° and 27. Crystalline oxotitanium phthalocyanine (crystal 2) with a major diffraction peak at 3 °,
Crystal oxotitanium phthalocyanine (crystal) having main diffraction peaks at Bragg angles 2θ (2θ ± 0.2 °) of 9.0 °, 14.2 °, 23.9 ° and 27.1 ° as shown in FIG. 3),
Crystalline oxotitanium phthalocyanine having a maximum diffraction peak at a Bragg angle 2θ (2θ ± 0.2 °) of 27.3 ° and having diffraction peaks at 7.4 °, 9.7 °, and 24.2 ° (crystal 4)
These can be used, and these can be used alone or in combination of two or more.

As described above, oxotitanium phthalocyanine having such a crystal structure not only has high charge generation capability and high charge injection efficiency, but is also high in light in a long wavelength region such as near infrared light and red light. Indicates sensitivity. Therefore, a photoconductor using oxotitanium phthalocyanine having such a crystal structure as a charge generation material is suitable for a digital electrophotographic apparatus that uses light in a long wavelength region emitted from a semiconductor laser, a light emitting diode, or the like as an exposure source. Can be used.
In particular, the above crystalline oxotitanium phthalocyanine has a stable crystal form and is unlikely to be transferred to another crystal form. An excellent photoreceptor can be obtained.
From such a viewpoint, crystals 1 to 4 are preferable, crystals 1 to 3 are more preferable, and crystal 1 is particularly preferable.

  The oxotitanium phthalocyanine having a crystal structure is obtained by subjecting the oxotitanium phthalocyanine obtained by hydrolysis to a pulverization (milling) treatment with mechanical strain in an organic solvent such as methyl ethyl ketone, or stirring for a sufficient time. The former method is preferable.

In addition, oxotitanium phthalocyanine having a crystal structure can be obtained by treating oxotitanium phthalocyanine with a water-immiscible organic solvent such as dichloroethane in the presence of water.
Specifically, there are a method of treating oxotitanium phthalocyanine swollen with water with an organic solvent, a method of adding water to an organic solvent without performing the swelling treatment, and introducing oxotitanium phthalocyanine into the solvent, etc. Although it is mentioned, it is not limited to these.

  Examples of the method for swelling oxotitanium phthalocyanine with water include, for example, a method in which oxotitanium phthalocyanine is dissolved in sulfuric acid and precipitated in water to form a wet paste, and stirring / dispersing devices such as homomixers, paint mixers, ball mills, sand mills, etc. Is used to swell oxotitanium phthalocyanine with water to form a wet paste, but is not limited to these methods.

  The above crystals 1 to 4 are disclosed in Japanese Patent No. 3569422 (Patent Document 9), Japanese Patent No. 2700859 (Patent Document 7), Japanese Patent Laid-Open No. 3-128973 (Patent Document 8) and Japanese Patent Publication No. 7- It can be produced by the method described in Japanese Patent No. 91486 (Patent Document 6).

[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.
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.

[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 oxotitanium phthalocyanine having the above-described crystal structure, which is a charge generation material having a charge generation capability of generating charges by absorbing irradiated light, and is arbitrarily known as described above. Contains additives and binder resin (binder).

The application method of the coating solution for the charge generation layer is a baker applicator method, a bar coater method (for example, a wire bar coater method), a casting method, a spin coating method, a roll method, a blade method, etc. Examples of the method include a spray method, a vertical ring method, and a dip coating method.
As an application method, an optimum method may be selected in consideration of physical properties and productivity of the coating liquid, and an immersion method, a blade coater method, and a spray method are particularly preferable.

  In the dip coating method, after immersing the conductive support 1 in a coating tank filled with a coating solution, the layer is formed on the conductive support 1 or the intermediate layer 2 by pulling up at a constant speed or a speed that changes sequentially. It is a method of forming. Since this method is relatively simple and excellent in terms of productivity and cost, it is widely used for manufacturing a photoreceptor. In addition, in order to stabilize the dispersibility of a coating liquid, you may provide the coating liquid dispersion | distribution apparatus represented by the ultrasonic generator in the apparatus used for a dip coating method.

  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.

  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, if the thickness of the charge generation layer exceeds 5 μm, charge transport within the charge generation layer becomes a rate-limiting step in the process of erasing the charge on the surface of the photoreceptor, and the sensitivity may be lowered.

[Charge transport layer 4]
The charge transport layer contains, as main components, a charge transport material having the ability to accept and transport charges generated by the charge generation material and a binder resin (binder).

As the charge transport material, a compound used in this field can be used.
Specifically, carbazole derivatives, imidazole derivatives, oxazole derivatives, thiadiazole derivatives, polycyclic aromatic compounds, aniline compounds, hydrazone compounds, aromatic amine compounds, triphenylamine compounds and their dimers, triphenyl Hole transport materials such as methane-based compounds, tetraphenylbutadiene-based compounds, enamine-based compounds and stilbene-based compounds, and polymers such as poly-N-vinylcarbazole having groups derived from these compounds in the main chain or side chain;

Fluorenone derivative, dibenzothiophene derivative, indenothiophene derivative, phenanthrenequinone derivative, indenopyridine derivative, thioxanthone derivative, benzo [c] cinnoline derivative, phenazine oxide derivative, tetracyanoethylene, tetracyanoquinodimethane, promanyl, chloranil And electron transport materials such as benzoquinone. These charge transport materials can be used alone or in combination of two or more.

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 is increased, and sufficient sensitivity may not be obtained.
On the other hand, if the ratio (E / B) exceeds 10/12, the printing durability of the charge transport layer and the durability of the photoreceptor may be lowered.

The binder resin can improve the mechanical strength and durability of the charge transport 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, etc., 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.
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 is one or two or more kinds selected from an antioxidant, a dispersion stabilizer, a leveling agent, a plasticizer, fine particles of an inorganic compound or an organic compound and the like within a range in which the preferable characteristics of the present invention are not impaired. An appropriate amount of known additives may be contained.

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 50 parts by weight with respect to 100 parts by weight of the charge generation material.
When the addition amount of the antioxidant is less than 0.1 parts by weight, there is a possibility that sufficient effects cannot be obtained for improving the stability of the coating liquid and improving the durability of the photoreceptor. On the other hand, when the added amount of the antioxidant 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 silicone leveling agents such as dimethyl silicone, diphenyl silicone and phenylmethyl silicone.
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 inorganic compound fine particles include metal oxide fine particles such as titanium oxide and silica. Examples of the fine particles of the organic compound include fine particles of fluorine atom-containing polymer such as tetrafluoroethylene polymer fine particles.

  The charge transport layer is prepared by dissolving or dispersing a charge transport material, a binder resin and, if necessary, other additives in an appropriate organic solvent to prepare a charge transport layer coating solution. It can be formed by applying to the surface and then drying to remove the organic solvent. More specifically, for example, a charge transport layer coating solution 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.

Examples of the organic solvent include aromatic hydrocarbons such as toluene, xylene, mesitylene, tetralin, diphenylmethane, dimethoxybenzene, and dichlorobenzene; halogenated hydrocarbons such as dichloromethane, dichloroethane, and tetrachloropropane; tetrahydrofuran (THF) and dioxane. , Ethers such as dibenzyl ether, dimethoxymethyl ether and 1,2-dimethoxyethane; ketones such as methyl ethyl ketone, cyclohexanone, acetophenone and isophorone; esters such as methyl benzoate, ethyl acetate and butyl acetate, and diphenyl sulfide Sulfur-containing solvents; Fluorine solvents such as hexafluoroisopropanol; aprotic polar solvents such as N, N-dimethylformamide and N, N-dimethylacetamide Etc., and these 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.
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, sharpness decreases and residual potential increases, There is a risk that image deterioration will occur remarkably.

[Intermediate layer (also called “undercoat layer”) 2]
The intermediate layer has a function of preventing charge injection from the conductive support to the laminated photosensitive layer. That is, a decrease in chargeability of the laminated photosensitive layer is suppressed, a decrease in surface charge other than a portion to be erased by exposure is suppressed, and 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 formed, for example, by dissolving the resin material in an appropriate solvent to prepare a coating solution for the intermediate layer, applying the coating solution to the surface of the conductive support, and removing the organic solvent by drying. it can.

As the intermediate layer, a resin layer made of various resin materials, an alumite layer, or the like is used.
Examples of the resin material constituting the resin layer include polyethylene resin, polypropylene resin, polystyrene resin, acrylic resin, vinyl chloride resin, vinyl acetate resin, polyurethane resin, epoxy resin, polyester resin, melamine resin, phenol resin, silicone resin, Examples thereof include a cellulose resin, a polyvinyl alcohol resin, a polyvinyl butyral resin, a polyvinyl acetal resin, and a polyamide resin, and a copolymer resin containing two or more repeating units constituting these resins.
Among these resins, polyamide resins, particularly alcohol-soluble nylon resins, and curable resins such as melamine resins, phenol resins, and polyurethane resins are preferably used.

Examples of the solvent for dissolving or dispersing the resin material include water, various organic solvents, and mixed solvents thereof. Among these, a single solvent such as water, methanol, ethanol or butanol; a mixed solvent of water and alcohols, two or more alcohols, acetone, methyl ethyl ketone or dioxolane and alcohols is preferably used.
Other processes and conditions are in accordance with the formation of the charge generation layer.

  Further, the intermediate layer may contain particles such as metal oxide particles. By containing these particles in the intermediate layer, the volume resistance value of the intermediate layer can be adjusted, and the effect of preventing the injection of charges from the conductive support to the photosensitive layer can be enhanced. In addition, the electrical characteristics of the photoreceptor 2 can be maintained under various environments, and environmental stability can be improved. Examples of the metal oxide particles that can be included include particles of titanium oxide, zinc oxide, aluminum oxide, antimony oxide, silicon oxide, indium oxide, zirconium oxide, magnesium oxide, aluminum hydroxide, tin oxide, and the like.

The ratio C / D of the total weight C of the resin and metal oxide and the weight D of the solvent in the intermediate layer coating solution is 1/99 to 40/60, preferably 2/98 to 30/70.
The ratio E / F between the weight E of the resin and the weight F of the metal oxide is 90/10 to 1/99, preferably 70/30 to 5/95.

  Although the film thickness of an intermediate | middle layer is not specifically limited, 0.05-20 micrometers is preferable and 0.1-10 micrometers is especially preferable. If the film thickness of the intermediate layer is less than 0.05 μm, it does not substantially 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 decrease. 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. A first intermediate layer (insulating layer or blocking layer) having a thickness of 0.2 to 1 μm containing no inorganic oxide fine particles and a second film having a thickness of 3 to 10 μm containing electrically conductive inorganic oxide fine particles. Examples include a combination with an intermediate layer (moire prevention layer).

[Protective layer (not shown)]
The photoreceptor of the present invention may have a protective layer (not shown) on the surface of the laminated 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 coating solution by dissolving or dispersing a binder resin and, if necessary, an additive such as an antioxidant or an ultraviolet absorber in a suitable organic solvent. It can be formed by applying a working solution to 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.

  Although the film thickness of a protective layer is not specifically limited, 0.5-10 micrometers is preferable and 1-5 micrometers is especially preferable. 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 is formed by exposure, the photosensitive member of the present invention, a charging unit for charging the photosensitive member, an exposure unit for exposing the charged photosensitive member to form an electrostatic latent image, and exposure. Developing means for developing the electrostatic latent image to form a toner image; transfer means for transferring the toner image formed by development onto a recording medium; and transferring the transferred toner image onto the recording material. The image forming apparatus includes at least a fixing unit that fixes and forms an image, a cleaning unit that removes and collects toner remaining on the photoconductor, and a static elimination unit that neutralizes surface charge remaining on the photoconductor.

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. 7 is a schematic side view showing the configuration of the image forming apparatus of the present invention.
The image forming apparatus 20 in FIG. 7 includes a photoconductor 21 (for example, any one of the photoconductors in FIGS. 1 to 3), a charging unit (charger) 24, an exposure unit 28, and a developing unit ( Development unit) 25, transfer unit (transfer unit) 26, cleaning unit (cleaner) 27, fixing unit (fixing unit) 31, and charge eliminating unit (not shown, attached to cleaning unit 27). Composed. Reference numeral 30 indicates 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 shows a bias power source.

  The exposure unit 28 includes, for example, a semiconductor laser as a light source, and is charged by irradiating light 28 a 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 photoconductor 21 is exposed according to image information. The light 28a 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 photosensitive member 24 is provided by the charger 24 provided on the upstream side in the rotational direction of the photosensitive member 21 with respect to the image forming point of the light 28a by the exposure means 28. The surface of 21 is uniformly charged to a predetermined positive or negative potential.

  Next, light 28 a corresponding to image information is irradiated from the exposure unit 28 to the surface of the photoconductor 21. With this exposure, the surface charge of the portion irradiated with the light 28a is removed from the photosensitive member 21, and a difference occurs between the surface potential of the portion irradiated with the light 28a and the surface potential of the portion not irradiated with the light 28a. An electrostatic latent image is formed.

  Next, 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 image forming point of the light 28a by the exposure unit 28. The electrostatic 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.

  Next, the transfer paper 30 onto which the toner image has been transferred is conveyed to the fixing device 31 by the conveying means, and is heated and pressurized when passing through the contact portion between the heating roller 31a and the pressure roller 31b of the fixing device 31. The toner 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 300 mm, and a thickness of 0.8 mm was used to produce the photoconductor of FIG.
First, dendritic titanium oxide surface-treated with aluminum oxide (Al ₂ O ₃ ) and zirconium dioxide (ZrO ₂ ) as metal oxide fine particles (manufactured by Ishihara Sangyo Co., Ltd., product name: TTO-D-1) ) 6 parts by weight and 4 parts by weight of copolymerized nylon resin (product name: Amilan CM8000, manufactured by Toray Industries, Inc.) are added to a mixed solvent of 50 parts by weight of 1,3-dioxolane and 40 parts by weight of methanol. Then, dispersion treatment was performed for 12 hours using a paint shaker to prepare an intermediate layer coating solution (total amount: 1 kg).
The obtained coating solution for forming an intermediate layer was filled in a coating tank, the conductive support was immersed, pulled up, and naturally dried to form an intermediate layer having a thickness of 1.0 μm.

Next, 3 parts by weight of crystalline oxotitanium phthalocyanine showing the diffraction peak of FIG. 3 prepared by the method described in Japanese Patent No. 3569422 (Patent Document 9) as a charge generating substance, and polyvinyl acetal of an aqueous polyol as a resin (Solid content: 20%, OH value: 570, manufactured by Sekisui Chemical Co., Ltd., product name: ESREC KW-3) and 1.7 parts by weight of a block isocyanate compound (solid content: 70%, NCO content: 7. 9%, manufactured by Asahi Kasei Chemicals Co., Ltd., developed product name: X1248) 2.4 parts by weight, antifoaming agent (oil compound type, manufactured by San Nopco Co., Ltd., product name: SN deformer 777) 0.005 parts by weight, stable dispersion Agent (manufactured by San Nopco, product name: Roma PWA-40): 0.008 parts by weight is added to 93 parts by weight of water, CGL coating liquid was 1 hour dispersion treatment with a chromatography mosquito (concentrated 1 kg) was prepared.
The isocyanate group of the blocked isocyanate compound is in a molar ratio of 1.0 to the active hydrogen-containing group of the resin, and the charge generation material (P) is 6 to the cross-linked resin (total of blocked isocyanate compound and resin: R). / 4 weight ratio (P / R).
The obtained charge generation coating solution was applied onto the previously formed intermediate layer by the same dip coating method as the intermediate layer, and the obtained coating film was dried and cured at a temperature of 130 ° C. for 30 minutes, A charge generation layer having a thickness of 0.3 μm was formed.

Next, 10 parts by weight of a triphenylamine-butadiene derivative represented by the following structural formula (1) as a charge transporting substance and 18 parts by weight of a polycarbonate resin (product name: Iupilon Z400, manufactured by Mitsubishi Engineering Plastics) as a binder resin Part, 0.5 part by weight of 2,6-di-t-butyl-4-methylphenol as an antioxidant, and dimethylpolysiloxane as a leveling agent (manufactured by Shin-Etsu Chemical Co., Ltd., product name: KF-96) ) 0.004 part by weight was dissolved in 110 parts by weight of tetrahydrofuran (THF) as an organic solvent to prepare a charge transport layer coating solution (total amount: 1 kg). This charge transport layer 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)
Instead of the crystalline oxotitanium phthalocyanine showing the diffraction peak of FIG. 3 as the charge generating substance, the crystalline oxotitanium phthalocyanine showing the diffraction peak of FIG. 4 prepared by the method described in Japanese Patent No. 2700859 (Patent Document 7) is used. A photoconductor of Example 2 was produced in the same manner as Example 1 except that it was used.
The isocyanate group of the blocked isocyanate compound in the coating solution for charge generation layer has a molar ratio of 1.0 to the active hydrogen-containing group of the resin, and the charge generation material (P) is a crosslinked resin (block isocyanate compound and resin of the resin). The weight ratio (P / R) was 6/4 with respect to the total: R).

(Example 3)
Instead of the crystalline oxotitanium phthalocyanine showing the diffraction peak of FIG. 3 as the charge generating substance, the crystalline oxotitanium phthalocyanine showing the diffraction peak of FIG. 5 prepared by the method described in JP-A-3-128973 (Patent Document 8) is used. A photoconductor of Example 3 was produced in the same manner as Example 1 except that was used.
The isocyanate group of the blocked isocyanate compound in the coating solution for charge generation layer has a molar ratio of 1.0 to the active hydrogen-containing group of the resin, and the charge generation material (P) is a crosslinked resin (block isocyanate compound and resin of the resin). The weight ratio (P / R) was 6/4 with respect to the total: R).

Example 4
As a charge generation material, instead of the crystalline oxotitanium phthalocyanine showing the diffraction peak of FIG. 3, it has a maximum diffraction peak at a Bragg angle (2θ ± 0.2 °) of 27.3 °, and 2 near 18 ° and 24 °. A photoconductor of Example 4 was produced in the same manner as in Example 1 except that Y-type oxotitanium phthalocyanine (manufactured by Orient Chemical Industry Co., Ltd.) showing two main diffraction peaks was used.
The isocyanate group of the blocked isocyanate compound in the coating solution for charge generation layer has a molar ratio of 1.0 to the active hydrogen-containing group of the resin, and the charge generation material (P) is a crosslinked resin (block isocyanate compound and resin of the resin). The weight ratio (P / R) was 6/4 with respect to the total: R).

(Example 5)
As a charge generation material, Bragg angles (2θ ± 0.2 °) 9.0, 14.2, 17.9, 23.9, 27.1 ° instead of the crystalline oxotitanium phthalocyanine having the diffraction peak of FIG. A photoconductor of Example 5 was produced in the same manner as in Example 1 except that type I oxotitanium phthalocyanine (manufactured by Orient Chemical Industry Co., Ltd.) showing a major diffraction peak was used.
The isocyanate group of the blocked isocyanate compound in the coating solution for charge generation layer has a molar ratio of 1.0 to the active hydrogen-containing group of the resin, and the charge generation material (P) is a crosslinked resin (block isocyanate compound and resin of the resin). The weight ratio (P / R) was 6/4 with respect to the total: R).

(Example 6)
As a charge generation material, instead of the crystalline oxotitanium phthalocyanine showing the diffraction peak of FIG. 3, it has a maximum diffraction peak at a Bragg angle (2θ ± 0.2 °) of 7.6 °, 10.2 °, 22.6. Except that α-type oxotitanium phthalocyanine (manufactured by Orient Chemical Co., Ltd.) having major diffraction peaks at °, 24.2 °, 26.3 °, and 28.6 ° was used, the same as Example 1 was used. Thus, a photoreceptor of Example 6 was produced.
The isocyanate group of the blocked isocyanate compound in the coating solution for charge generation layer has a molar ratio of 1.0 to the active hydrogen-containing group of the resin, and the charge generation material (P) is a crosslinked resin (block isocyanate compound and resin of the resin). The weight ratio (P / R) was 6/4 with respect to the total: R).

(Example 7)
The isocyanate group of the blocked isocyanate compound in the coating solution for charge generation layer has a molar ratio of 1.3 to the active hydrogen-containing group of the resin, and the charge generation material (P) is a crosslinked resin (block isocyanate compound and resin of the resin). A photoconductor of Example 7 was produced in the same manner as in Example 1 except that the weight ratio (P / R) was 6/4 with respect to the total (R).

(Example 8)
The isocyanate group of the blocked isocyanate compound in the charge generation layer coating solution has a molar ratio of 0.7 to the active hydrogen-containing group of the resin, and the charge generation material (P) is a crosslinked resin (of the blocked isocyanate compound and the resin). A photoconductor of Example 8 was produced in the same manner as in Example 1 except that the weight ratio (P / R) was 6/4 with respect to the total (R).

Example 9
The isocyanate group of the blocked isocyanate compound in the charge generation layer coating solution has a molar ratio of 0.4 to the active hydrogen-containing group of the resin, and the charge generation material (P) is a crosslinked resin (blocked isocyanate compound and resin A photoconductor of Example 9 was produced in the same manner as in Example 1 except that the weight ratio (P / R) was 6/4 with respect to the total (R).

(Example 10)
The isocyanate group of the blocked isocyanate compound in the charge generation layer coating solution has a molar ratio of 1.6 to the active hydrogen-containing group of the resin, and the charge generation material (P) is a crosslinked resin (blocked isocyanate compound and resin of the resin). A photoconductor of Example 10 was produced in the same manner as in Example 1 except that the weight ratio (P / R) was 6/4 with respect to the total (R).

(Example 11)
A photoconductor of Example 11 was produced in the same manner as Example 1 except that the charge generation layer coating solution was prepared with the following components.
Crystalline oxotitanium phthalocyanine showing the diffraction peak of FIG. 3 as a charge generating substance (manufactured by Orient Chemical Co., Ltd.): 3 parts by weight Water-soluble cellulose as a resin (OH number: 360, manufactured by Shin-Etsu Chemical Co., Ltd., product name) : Metroles 65SH-50): 0.27 parts by weight Block isocyanate compound (solid content: 70%, NCO content: 4.3%, manufactured by Asahi Kasei Chemicals Corporation, developed product name: X1458) 2.5 parts by weight Antifoaming agent (Oil compound system, manufactured by San Nopco, product name: SN deformer 777): 0.005 parts by weight Dispersion stabilizer (manufactured by San Nopco, product name: Roma PWA-40): 0.008 parts by weight 94 parts by weight of water The isocyanate group of the blocked isocyanate compound has a molar ratio of 1.0 to the active hydrogen-containing group of the resin. Load generating substance (P) is, (sum of blocked isocyanate compound and a resin: R) crosslinked resin had a weight ratio of 6/4 with respect to (P / R).

(Example 12)
A photoconductor of Example 12 was produced in the same manner as in Example 1 except that the charge generation layer coating solution was prepared with the following components.
Crystalline oxotitanium phthalocyanine showing the diffraction peak of FIG. 3 as a charge generating substance (manufactured by Orient Chemical Industry Co., Ltd.): 3 parts by weight Polyether polyol as a resin (solid content: 35%, OH value: 60, Nippon Polyurethane Industry) Product name: AQD-473): 3.6 parts by weight Block isocyanate compound (solid content: 42%, NCO content: 7.5%, Nippon Polyurethane Industry Co., Ltd., developed product name: BWD-102) : 1.8 parts by weight Antifoaming agent (oil compound, San Nopco, product name: SN deformer 777): 0.005 parts by weight Dispersion stabilizer (San Nopco, product name: Roma PWA-40): 0.008 parts by weight Water 92 parts by weight The isocyanate group of the blocked isocyanate compound is an active hydrogen-containing group of the resin. In a molar ratio of 1.0 for a charge generation material (P) is, (sum of blocked isocyanate compound and a resin: R) crosslinked resin had a weight ratio of 6/4 with respect to (P / R).

(Example 13)
A photoconductor of Example 13 was produced in the same manner as Example 1 except that the charge generation layer coating solution was prepared with the following components.
Crystalline oxotitanium phthalocyanine showing the diffraction peak of FIG. 3 as a charge generating substance (manufactured by Orient Chemical Co., Ltd.): 3 parts by weight Polyvinyl acetal of an aqueous polyol as a resin (solid content: 20%, OH value: 960, Sekisui Chemical Industrial Co., Ltd., product name: ESREC KW-1): 0.49 parts by weight Block isocyanate compound (solid content: 37.5%, NCO content: 3.7%, Sumika Bayer Urethane Co., Ltd., product Name: Bihijoule VPLS2310): 5.1 parts by weight Defoaming agent (oil compound, manufactured by San Nopco, product name: SN deformer 777): 0.005 parts by weight Dispersion stabilizer (produced by San Nopco, product name: Rome) PWA-40): 0.008 part by weight Water 91 part by weight Isocyanate of blocked isocyanate compound The charge group (P) has a molar ratio of 1.0 to the active hydrogen-containing group of the resin, and the charge generation material (P) has a ratio of 6/4 to the cross-linked resin (total of the blocked isocyanate compound and the resin: R). It was a weight ratio (P / R).

(Example 14)
A photoconductor of Example 14 was produced in the same manner as Example 1 except that the charge generation layer coating solution was prepared with the following components.
Crystalline oxotitanium phthalocyanine showing the diffraction peak of FIG. 3 as a charge generating substance (manufactured by Orient Chemical Industries, Ltd.): 3 parts by weight Water-soluble nylon as a resin (solid content: 20%, NH content: 10%, Nagase Manufactured by Chemtex Co., Ltd., product name: Toresin FS-350): 2.2 parts by weight Block isocyanate compound (solid content: 45%, NCO content: 7.0%, manufactured by Mitsui Chemicals Polyurethane Co., Ltd., product name: Takenate WB-820): 3.5 parts by weight Antifoaming agent (oil compound, San Nopco, product name: SN deformer 480): 0.005 parts by weight Dispersion stabilizer (San Nopco, product name: Roma PWA) −40): 0.008 part by weight 91 parts by weight of water The isocyanate group of the blocked isocyanate compound is the active water of the resin. The charge generation material (P) was 6/4 weight ratio (P / R) to the cross-linked resin (total of blocked isocyanate compound and resin: R) at a molar ratio of 1.0 to the containing group. It was.

(Example 15)
A photoconductor of Example 15 was produced in the same manner as Example 1 except that the charge generation layer coating solution was prepared with the following components.
Crystalline oxotitanium phthalocyanine showing the diffraction peak of FIG. 3 as a charge generation material (manufactured by Orient Chemical Industries): 3 parts by weight Aqueous polyacrylic polyol as resin (solid content: 45%, OH value: 80, DIC stock) Product name: Burnock WE-300): 2.1 parts by weight Block isocyanate compound (solid content: 40%, NCO content: 5.4%, manufactured by Mitsui Chemicals Polyurethane Co., Ltd., product name: Takenate WB-920) ): 2.6 parts by weight Antifoaming agent (oil compound type, manufactured by San Nopco, product name: SN deformer 470): 0.005 parts by weight Dispersion stabilizer (manufactured by San Nopco, product name: SN Dispersant 5468) : 0.008 part by weight 92 parts by weight of water The isocyanate group of the blocked isocyanate compound is The charge generation material (P) is 6/4 weight ratio (P / R) to the cross-linked resin (total of blocked isocyanate compound and resin: R) at a molar ratio of 1.0 to the functional hydrogen-containing group. Met.

(Comparative Example 1)
A photoconductor of Comparative Example 15 was produced in the same manner as in Example 1 except that the charge generation layer coating solution was prepared with the following components (organic solvent-based, uncured).
Crystalline oxotitanium phthalocyanine showing the diffraction peak of FIG. 3 as a charge generation material (manufactured by Orient Chemical Co., Ltd.): 3 parts by weight Polyvinyl butyral as a resin (product name: BM-S): 2 parts by weight Methyl ethyl ketone as an organic solvent: 145 parts by weight

(Comparative Example 2)
The photosensitivity of Comparative Example 2 was the same as that of Comparative Example 1, except that the crystalline oxotitanium phthalocyanine having the diffraction peak of FIG. 4 was used as the charge generation material instead of the crystalline oxotitanium phthalocyanine having the diffraction peak of FIG. The body was made.

(Comparative Example 3)
A photoconductor of Comparative Example 3 was produced in the same manner as in Example 1 except that the charge generation layer coating solution was prepared with the following components (aqueous, no curing agent).
Crystalline oxotitanium phthalocyanine showing the diffraction peak of FIG. 3 as a charge generating substance (manufactured by Orient Chemical Industries Co., Ltd.): 3 parts by weight Polyvinyl acetal resin of an aqueous polyol as a resin (solid content: 20%, OH value: 570) , Manufactured by Sekisui Chemical Co., Ltd., product name: ESREC KW-3): 10 parts by weight water: 87 parts by weight

(Comparative Example 4)
A photoconductor of Comparative Example 4 was prepared in the same manner as Comparative Example 1 except that X-type metal-free oxotitanium phthalocyanine was used as the charge generation material instead of the crystalline oxotitanium phthalocyanine showing the diffraction peak of FIG. .

(Comparative Example 5)
The photosensitivity of Comparative Example 5 was the same as that of Comparative Example 1 except that a trisazo pigment represented by the following structural formula (2) was used as the charge generation material instead of the crystalline oxotitanium phthalocyanine showing the diffraction peak of FIG. The body was made.

(Comparative Example 6)
A photoconductor of Comparative Example 6 was produced in the same manner as in Example 1 except that the charge generation layer coating solution was prepared with the following components (an aqueous, non-block type isocyanate compound (20 ° C., NCO group at 20 hours). Use completely)).
Crystalline oxotitanium phthalocyanine showing the diffraction peak of FIG. 3 as a charge generating substance (manufactured by Orient Chemical Industry Co., Ltd.): 3 parts by weight Polyvinyl acetal as a resin (solid content: 20%, OH value: 570, Sekisui Chemical Co., Ltd.) Product name: ESREC KW-3): 2.8 parts by weight Water-dispersed isocyanate (non-block type, NCO content: 16.5%, manufactured by Asahi Kasei Chemicals Corporation, product name: Duranate WB40-100): 1.4 parts by weight Antifoaming agent (polyether, manufactured by San Nopco, product name: SN deformer 470): 0.005 parts by weight Dispersion stabilizer (manufactured by San Nopco, product name: Roma PWA-40): 0 0.008 part by weight Water: 93 part by weight The isocyanate group of the blocked isocyanate compound is based on the active hydrogen-containing group of the resin. In a molar ratio of 1.0, the charge-generating substance (G) is (the sum of the blocked isocyanate compound and resin: R) crosslinked resin had a weight ratio of 6/4 with respect to (G / R).
Table 1 shows the materials and weight ratios P / R used in Examples 1 to 14 and Comparative Examples 1 to 4.

(Evaluation)
(1) Electrical Characteristics and Environmental Stability of Photoreceptor The photoreceptor obtained in Examples 1 to 15 and Comparative Examples 1 to 6 was measured with a surface potential meter (Gen) so that the surface potential of the photoreceptor in the image forming process could be measured. Each of the photoconductors was evaluated for electrical characteristics and environmental stability by being mounted on a commercially available digital copying machine (manufactured by Sharp Corporation, model: MX-501FN) provided with Tech Co., Ltd. (model: CATE751).
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 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).
The obtained results are shown in Table 2. In Table 2, the solvent used for the intermediate layer coating solution is additionally shown.

Further, a blank paper image was output under an H / H environment at a temperature of 30 ° C. and a relative humidity of 80%, and black spots were evaluated based on the following criteria.
○: None △: Slightly observed (practical)
×: Observed clearly (not practical)
The obtained results are shown in Table 2.

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.
The obtained results are shown in Table 2.

(2) Pot life The charge generation layer coating solutions prepared in Examples 1 to 15 and Comparative Examples 1 to 6 were stored for 6 months under normal temperature and normal humidity (temperature 20 ° C., humidity 50%), and then the same manner. The residual potential VL (V) in an N / N environment is measured for the obtained photosensitive member, and the difference from the value of the initial residual potential VL (V) in the above (1) is determined. It was determined as a potential fluctuation ΔVLP (V) serving as an index of pot life.
The obtained results are shown in Table 2.

From the results of Tables 1 and 2, the following can be understood.
(1) The photoreceptors of the present invention (Examples 1 to 15) are polyamide-based materials that are widely used in current photoreceptors, even though water is used as a solvent for the charge generation layer coating solution. Compared with the organic solvent-based photoconductors of Comparative Examples 1 and 2 using a binder resin, all of the electrical characteristics, environmental stability, fatigue characteristics, and coating liquid stability (pot life) are equivalent or better. ing.
This is because oxo titanyl phthalocyanine having a crystal structure as a charge generation material has high sensitivity, and thus excellent electrical characteristics are obtained, and environmental stability, fatigue characteristics and coating properties are obtained by thermosetting the charge generation layer. This is probably because liquid stability (pot life) was obtained.

(2) The environmental characteristics of the photoconductor (Comparative Example 3) having a charge generation layer formed using a water-based, curing agent-free charge generation layer coating solution were extremely deteriorated.
This is presumably because oxotitanium phthalocyanine having a crystal structure as a charge generating substance is susceptible to fluctuations in sensitivity depending on the environment such as humidity and the environmental characteristics are deteriorated. Moreover, the result of the image defect (black dot) in Comparative Example 3 also suggests a fluctuation in sensitivity.

(3) Photoconductors (Comparative Examples 4 and 5) using X-type metal-free oxotitanium phthalocyanine and trisazo pigment as charge generating materials have lower sensitivity than the photoconductors of the present invention (Examples 1 to 15), and VL The result was high.
This is presumably because X-type metal-free oxotitanium phthalocyanine and trisazo pigment are inferior in charge generation ability and charge injection efficiency compared to oxotitanium phthalocyanine having a crystal structure. That is, in the charge generation material having low sensitivity, the amount of charge generated by light absorption is small, and as a result, the amount of charge transported to the surface of the photoreceptor is also small, and VL is increased.

(4) The photoconductor (Comparative Example 6) having a charge generation layer formed using a non-blocking isocyanate compound as a curing agent has a much worse pot life than the photoconductor of the present invention (Examples 1 to 15). did. This is characterized in that the isocyanate group in the isocyanate compound easily reacts with water, and the blocked isocyanate compound in which the isocyanate group is protected by the protective group does not easily react with water, but the isocyanate group is exposed. It is considered that a certain non-block type isocyanate compound easily reacts with water.

1 conductive support 2 intermediate layer (undercoat layer)
3 Charge Generation Layer 4 Charge Transport Layer 5 Multilayer Photosensitive Layer

20 Image forming apparatus 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 Light 30 Transfer paper 31 Fixing means (fixing device)
31a Heating roller 31b Pressure roller

Claims (10)

On the conductive support, at least a charge generation layer and a charge transport layer are laminated,
The charge generation layer comprises a charge generation layer coating solution containing a charge generation material, 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 an aqueous medium. An electrophotographic photoreceptor, which is a layer formed through thermosetting, and wherein the charge generation material is oxotitanium phthalocyanine having a crystal structure.   The electrophotographic photoreceptor according to claim 1, wherein the active hydrogen-containing group is a hydroxyl group or an amide group.   The electrophotographic photoreceptor according to claim 1, wherein 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.   The electrophotographic photoreceptor according to any one of claims 1 to 3, wherein the blocked isocyanate compound has a structure in which hexamethylene diisocyanate or isophorone diisocyanate is blocked with an oxime or lactam blocking agent.   5. The resin according to claim 1, wherein the resin is selected from a polyether polyol resin, a polyester polyol resin, a polyacryl polyol resin, a polyvinyl alcohol resin, a polyvinyl acetal resin, cellulose, and a polyamide resin. The electrophotographic photoreceptor described in 1.   The oxotitanium phthalocyanine having the crystal structure shows a diffraction peak at least at a Bragg angle (2θ ± 0.2 °) of 27.1 to 27.3 ° in an X-ray diffraction spectrum using a CuKα ray (1.541Å). The electrophotographic photosensitive member according to claim 1.   The oxotitanium phthalocyanine having the crystal structure has a maximum diffraction peak at a Bragg angle (2θ ± 0.2 °) of 9.4 ° in an X-ray diffraction spectrum using CuKα rays (1.541Å), at least 7. Diffraction peaks are shown at 3 °, 9.7 °, and 27.3 °, and 9.4 ° and 9.7 ° have distinct branching peaks, which are larger than the diffraction peak at 27.3 °. The electrophotographic photosensitive member according to claim 6, wherein   The oxotitanium phthalocyanine having the above crystal structure has a Bragg angle (2θ ± 0.2 °) of 9.5 °, 9.7 °, 11.7 ° in an X-ray diffraction spectrum using CuKα rays (1.541 °). The electrophotographic photosensitive member according to claim 6, which exhibits major diffraction peaks at 15.0 °, 23.5 °, 24.1 ° and 27.3 °.   The oxotitanium phthalocyanine having the above crystal structure has a Bragg angle (2θ ± 0.2 °) of 9.0 °, 14.2 °, 23.9 ° in an X-ray diffraction spectrum using CuKα rays (1.541Å). The electrophotographic photosensitive member according to claim 6, which exhibits a major diffraction peak at 27.1 °.   The electrophotographic photosensitive member according to claim 1, a charging unit for charging the electrophotographic photosensitive member, and exposing the charged electrophotographic photosensitive member to form an electrostatic latent image. Exposure means; development means for developing the electrostatic latent image formed by exposure to form a toner image; transfer means for transferring the toner image formed by development onto a recording material; Fixing means for fixing a toner image on the recording material to form an image; cleaning means for removing and collecting toner remaining on the electrophotographic photosensitive member; and removing surface charges remaining on the electrophotographic photosensitive member. An image forming apparatus comprising at least a charge eliminating unit.

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