JP5358161B2 - Electrophotographic photosensitive member and image forming apparatus using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor provided with an intermediate layer which has improved environmental stability, repeating properties and leak resistance with which image defects such as black dots are prevented, is hard to be influenced by the surface properties of an electroconductive substrate, and has a well-balance in production cost, productivity and performance. <P>SOLUTION: In the electrophotographic photoreceptor obtained by successively laminating an intermediate layer and an organic photosensitive layer on an electroconductive substrate, the intermediate layer is obtained by applying an application liquid for forming an intermediate layer in which at least a block isocyanate compound, a resin having an active hydrogen-containing group capable of reacting with an isocyanate group in the block isocyanate compound, inorganic oxide fine particles and an electron transport agent are dissolved or dispersed into a water base medium, and thermally hardening the same, and has a thickness of &gt;10 &mu;m and &le;50 &mu;m. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to an electrophotographic photosensitive member and an image forming apparatus using the same. More specifically, the present invention relates to an electrophotographic photosensitive member having a thick intermediate layer and an image forming apparatus using 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.

The intermediate layer can be used to improve the adhesion of the photosensitive layer by coating defects on the conductive support, improve film formability (coatability), prevent unnecessary charge injection from the conductive support, and improve the chargeability associated therewith. It has a function.
An intermediate | middle layer is divided roughly into what consists of resin independent, and what consists of resin containing the pigment.
Examples of the resin used for the intermediate layer include water-soluble resins such as polyvinyl alcohol and casein, alcohol-soluble resins such as copolymer nylon resins, polyurethane, melamine resins, phenol resins, alkyd resins, epoxy resins, and siloxane resins. Examples thereof include a thermosetting resin that forms a network structure.

However, since water-soluble resins and alcohol-soluble resins are rich in moisture adsorption and affinity, there is a problem that physical properties are extremely dependent on the environment, and the characteristics of the photoreceptor are changed by humidity. In particular, since the intermediate layer absorbs a large amount of moisture at high humidity, repeated use of the photoreceptor at high temperature and high humidity or low temperature and low humidity greatly changes its characteristics and causes abnormal images such as black spots and density reduction.
Therefore, a thermosetting resin that forms a three-dimensional network structure excellent in solvent resistance and environmental stability was adopted.

  However, for example, melamine resins disclosed in Japanese Patent No. 3657138 (Patent Document 1), for example, resins such as phenol resin and methoxymethylated nylon disclosed in Japanese Patent No. 2707341 (Patent Document 2) Formaldehyde, which is said to be one of the causative substances of sick house syndrome at the time of resin production and is currently listed as a target substance in the Air Pollution Control Law, is used in large quantities. Therefore, there is a problem that unreacted substances during production are occluded in the resin, and formaldehyde is generated in the process of thermal crosslinking after the formation of the intermediate layer of the photoreceptor. In order to prevent the release of the generated formaldehyde into the atmosphere, a recovery facility is necessary, and it is obviously expensive to introduce the facility.

In addition, for example, in the urethane resin disclosed in Japanese Patent No. 2790380 (Patent Document 3), an active hydrogen-containing group such as a polyol compound and an isocyanate group of an isocyanate compound that is a curing agent have a three-dimensional network cross-linking reaction. No formaldehyde is generated since a cured film is formed. However, since the reactivity of the isocyanate group is very high, there is a problem that the pot life of the coating liquid using these is very short.
Therefore, a method using a blocked isocyanate compound in which an isocyanate group is protected with a blocking agent such as oxime has been reported, and the pot life of a coating solution using an organic solvent has been considerably improved (for example, JP-A-2005-115351). (See Patent Document 4).

  Furthermore, the demand for longer life (long life) for electrophotographic photoreceptors in recent years is vigorous, and related demands for the basic functions (chargeability, charge retention, light attenuation) and image quality stability of the photoreceptors. Increasingly. In particular, the generation of local image quality defects that hinder stabilization is one of the major issues. Causes of the occurrence include contamination on the conductive support, nonuniformity of the charge generation agent particles in the charge generation layer, local leakage due to foreign matter biting into the surface layer of the photoreceptor, and instability of the intermediate layer. The occurrence of image quality degradation can be mentioned. That is, in order to improve the repetitive stability and environmental stability of the photoreceptor when used in an electrophotographic apparatus, and to prevent the occurrence of the above-mentioned image quality defects, not only the improvement of the performance of the photosensitive layer but also the photosensitive layer It is also necessary to improve the performance of the undercoat layer (intermediate layer) serving as the foundation of the substrate. Specifically, it is required to form an intermediate layer having a small charge storage property by repeated use.

As one effective method for improving the leak resistance of the intermediate layer, it is effective to increase the thickness of the intermediate layer. At this time, if the resistance value of the intermediate layer is not reduced, charge accumulation occurs in the intermediate layer, and the residual potential increases. On the contrary, in order to lower the resistance value, an oxide filler is added (see Japanese Patent Application Laid-Open No. 2003-91086 (Patent Document 5)). However, excessive addition deteriorates the film quality as the intermediate layer, and causes an increase in peelability and a decrease in chargeability, so it is very difficult to maintain a balance between sensitivity and chargeability.
As a new solution, Japanese Patent Application Laid-Open No. 2006-30699 (Patent Document 6) and Japanese Patent Application Laid-Open No. 2007-108665 (Patent Document 7) use a specific electron transfer agent to thereby improve the chargeability and leakage resistance. Means for improving the balance is described. However, the effect obtained by that means is not sufficient.

Japanese Patent No. 3657138 Japanese Patent No. 2707341 Japanese Patent No. 2790380 JP-A-2005-115351 JP 2003-91086 A JP 2006-30699 A JP 2007-108665 A

  The present invention prevents environmental defects and image defects such as repetitive characteristics and black spots, that is, improves leakage resistance, is less affected by the surface shape of the conductive substrate, and has reduced manufacturing costs, productivity, and performance. It is an object of the present invention to provide an electrophotographic photosensitive member having a balanced intermediate layer.

Thus, according to the present invention, there is provided an electrophotographic photosensitive member in which an intermediate layer and an organic photosensitive layer are sequentially laminated on a conductive substrate,
In the intermediate layer, at least a blocked isocyanate compound, a resin having an active hydrogen-containing group capable of reacting with an isocyanate group in the blocked isocyanate compound, inorganic oxide fine particles, and an electron transport agent are dissolved or dispersed in water . An electrophotographic photosensitive member is provided which is obtained by applying and heat-curing a coating solution for forming an intermediate layer and has a thickness of greater than 10 μm and less than or equal to 50 μm.

  According to the present invention, the electrophotographic photosensitive member, a charging unit for charging the electrophotographic photosensitive member, and exposure for forming an electrostatic latent image by exposing the charged electrophotographic photosensitive member to exposure. Developing means for developing the electrostatic latent image to form a toner image, transfer means for transferring the toner image onto a recording material, and fixing the transferred toner image on the recording material. An image comprising: a fixing unit that forms an image; a cleaning unit that removes and collects toner remaining on the electrophotographic photosensitive member; and a neutralizing unit that neutralizes surface charges remaining on the electrophotographic photosensitive member. A forming apparatus is provided.

According to the present invention, by increasing the thickness of the intermediate layer, it is possible to provide an electrophotographic photosensitive member having an intermediate layer with a small environmental load and excellent chargeability and stability.
Furthermore, since the inorganic oxide fine particles and the electron transport agent that provide a balance between the charging property and the conductivity are included, the electric resistance of the intermediate layer can be easily controlled. As a result, the film thickness of the intermediate layer can be made larger than 10 μm and less than 50 μm, and image stability such as environmental stability and repetitive characteristics and black spots can be prevented, that is, leakage resistance is improved and stable. A high performance electrophotographic photoreceptor can be provided.

When the coating liquid for forming an intermediate layer contains an aqueous medium, air pollution due to VOC in the manufacturing process can be eliminated. In addition, there is no CO ₂ emission as in the case of petroleum-based solvents that have been used conventionally. Therefore, it contributes to the prevention of global warming. Furthermore, since there is no risk of fire, the manufacturing system can be simplified and the manufacturing cost can be reduced.
Further, when an aqueous solvent is used, it is desired to use a resin having a high affinity for water. When such a resin is used, the moisture resistance of the electrophotographic photosensitive member may be lowered. However, moisture resistance is achieved by reducing the hydrophilic functional groups in the resin by heat-curing the resin having an active hydrogen capable of reacting with an isocyanate group with an isocyanate compound, and curing the coating to make it dense. Can be improved. As a result of the improvement, excellent environmental stability is obtained.

  Furthermore, although the isocyanate group easily reacts with water, a pot life equivalent to that of a conventional organic solvent-based coating solution can be realized by using a blocked isocyanate compound in which the isocyanate group is protected with a protecting group. Therefore, even when an aqueous medium is used, a coating solution that is stable for a long period of time can be prepared, and an intermediate layer having excellent moisture resistance can be formed.

In addition, when the intermediate layer has a thickness greater than 10 μm and not more than 30 μm, it is difficult to be influenced by the surface shape of the conductive substrate, and an electrophotographic film that balances cost, productivity, and performance as the intermediate layer. A photoreceptor can be provided.
In addition, when the electron transport agent is an anthraquinone derivative, a more stable electrophotographic photoreceptor can be provided. Furthermore, when the anthraquinone derivative is alizarin, a more stable electrophotographic photoreceptor can be provided.

When the inorganic oxide fine particles are fine particles of titanium oxide or zinc oxide, the electric resistance of the intermediate layer can be easily controlled, and image defects such as repetitive characteristics and black spots can be prevented. Furthermore, when the inorganic oxide fine particles are fine particles having an average primary particle size of 20 to 500 nm, image defects can be further prevented.
Further, according to the present invention, it is possible to provide an image forming apparatus excellent in repetitive characteristics and environmental stability.

The intermediate layer of the photoreceptor of the present invention comprises at least a blocked isocyanate compound, a resin having two or more active hydrogen-containing groups capable of reacting with an isocyanate group in the blocked isocyanate compound, inorganic oxide fine particles, an electron transport agent, It is obtained by applying and heat-curing a coating solution for forming an intermediate layer in which is dissolved or dispersed in an aqueous medium.
A blocked isocyanate compound is a compound in which an isocyanate group of an organic 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 organic 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, carboxyl group or sulfonic acid group, or dissolved or self-emulsified. 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 diisocyanates such as hexamethylene diisocyanate and isophorone diisocyanate are easy to have an affinity for water, so that they can be easily dissolved and dispersed in water, and the crosslinking density can be easily increased. Therefore, it is particularly preferable.

In addition, various prepolymers derived from organic polyisocyanates, and further as blocking agents for blocking isocyanate groups in these organic polyisocyanates include active methylene compounds such as ethyl acetate and acetylacetone; butyl mercaptan , Mercaptan compounds such as dodecyl mercaptan, acid amide compounds such as acetanilide and acetic acid amide; lactam compounds such as ε-caprolactam, δ-valerolactam and γ-butyrolactam; acid imides such as succinimide and maleic acid imide Compounds: Imidazole compounds such as imidazole and 2-methylimidazole; Urea compounds such as urea, thiourea and ethyleneurea; Formamide oxime, acetoaldoxime, acetone oxime, methyl ethyl keto Oxime compounds such as shim, methyl isobutyl ketoxime, cyclohexanone oxime; amine compounds such as diphenylaniline, aniline, carbazole, ethyleneimine, polyethyleneimine, etc. 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 blocked isocyanate compound preferably has a structure in which xamethylene 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-700WB-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 two or more active hydrogen-containing groups capable of reacting with the isocyanate group in the blocked isocyanate compound is preferably a hydroxyl group or an amide group capable of reacting with the isocyanate group in a high yield.
That is, it has two or more hydroxyl groups or amide groups to form a crosslinked structure with the blocked isocyanate as a curing agent (if it has only one functional group, it does not have a crosslinked structure but has a high molecular weight). Polyol resins and polyamide resins are preferred. Moreover, by controlling the structure of these polyol resins and polyamide resins, they can be dispersed and dissolved in water well, and these resins have high adhesion to the substrate. Image defects due to poor contact with the substrate when used as a photoreceptor can also be effectively prevented.

As the resin, for example,
Product name: AQD-457 and AQD-473, Asahi Glass Co., Ltd., product name: Exenol 420 and 720, Sanyo Chemical Industries, Ltd., product name: Sannix GP-400, GP-700 And polyether polyol resins such as SP-750;
Hitachi Chemical Co., Ltd., product name: Phthalkid W2343, DIC Corporation, product name: Watersol S-118, CD-520 and BCD-3040, Harima Kasei Co., Ltd., product name: Hallidip WH-1188, etc. Polyester polyol resins of
Product name: Burnock WE-300, WE-304 and WE-306, manufactured by Asia Industry Co., Ltd., product name: WAP-473-FD and WAP-548, manufactured by DIC Corporation;
Manufactured by Kuraray Co., Ltd., product name: polyvinyl alcohol resins such as modified polyvinyl alcohols such as Kuraray Poval PVA-203 and PVA-205;
Manufactured by Sekisui Chemical Co., Ltd., product name: polyvinyl acetal resins such as ESREC K KW-1 and KW-3;
Manufactured by Shin-Etsu Chemical Co., Ltd., product name: cellulose such as water-soluble cellulose ethers such as Metroles 65SH-50 and 65SH-400;
Made by Nagase ChemteX Corporation, product name: Water-soluble nylon (polyamide compound resin) such as Toresin FS-350 and FS-500
Etc.

The isocyanate group (H) of the blocked isocyanate compound is preferably 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 intermediate layer forming coating solution further contains inorganic oxide fine particles.
The inorganic oxide fine particles adjust the volume resistance value of the intermediate layer when it is used as a photoconductor to prevent the injection of carriers from the conductive support to the photoconductive layer, and to improve the electric characteristics of the photoconductor in various environments. It has a function to maintain.
Examples of the inorganic oxide fine particles include fine particles such as titanium oxide, aluminum oxide, tin oxide, zinc oxide, antimony oxide, silicon oxide, indium oxide, zirconium oxide, magnesium oxide, and barium sulfate. Among these, fine particles of titanium oxide, zinc oxide and aluminum oxide are preferable from the viewpoint of conductivity and dispersibility, and fine particles of titanium oxide and zinc oxide are particularly preferable.
The shape of the inorganic oxide fine particles may be any of dendritic, acicular and granular.
The average primary particle size of the inorganic oxide fine particles is preferably about 20 to 500 nm.

As inorganic oxide fine particles, for example,
Ishihara Sangyo Co., Ltd., product name: TTO-55D (shape: granular, average primary particle size: 30-50 nm), TTO-D-1 (shape: dendritic, average primary particle size: minor axis 30-50 nm, long (Axis: 200 to 300 nm), ST21 (shape: granular, average primary particle size (measured by X-ray): 70 nm), PT401M (shape: granular, average primary particle size: 70 nm) and CR-EL (shape: granular, average primary) Particle size: 250 nm),
Product name: GTR100 (shape: granular, average primary particle size: 260 nm), manufactured by Sakai Chemical Industry Co., Ltd.
Product name: MT-500SAS (shape: granular, average primary particle size: 35 nm) and JR603 (shape: granular, average primary particle size: 280 nm)
Fine particles of titanium oxide such as
Ishihara Sangyo Co., Ltd., product name: FZO50 (shape: granular, average primary particle size: 21 nm),
Product name: FINEX30 (shape: granular, average primary particle size: 35 nm), manufactured by Sakai Chemical Industry Co., Ltd.
Product name: MZ300 (shape: granular, average primary particle size: 30-40 nm)
Product name: F2 (Shape: granular, average primary particle size: 65 nm), manufactured by Hisui Tech Co., Ltd.
And zinc oxide fine particles.

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

Moreover, the coating liquid for intermediate | middle layer formation contains the electron transport agent. The conductivity of the intermediate layer can be adjusted by the electron transfer agent.
Examples of the electron transport agent include perylene dyes, pyrylium dyes, thioindigos, quinones such as diphenoquinone and naphthoquinone derivatives or naphthalenecarboxylic acid derivatives, cyano compounds such as tetracyanoethylene and terephthalmalondinitrile, 4 -Aldehydes such as nitrobenzaldehyde and anthraquinones such as anthraquinone and alizarin.
Among these, anthraquinone derivatives represented by the following formulas (1-1) to (1-8) are a desirable group of compounds. Furthermore, alizarin represented by (1-7) is preferred.

  The addition amount of the electron transfer agent can be arbitrarily set as long as desired characteristics can be obtained. When the thickness of the intermediate layer is set to be greater than 10 μm and 50 μm or less, preferably in the range of 1 to 10% by weight, the chargeability / leakage resistance and sensitivity characteristics can be achieved at a high level. When the amount is less than 1% by weight, sufficient electron transport properties cannot be obtained, and problems such as an increase in residual potential may occur. On the other hand, when the content exceeds 10% by weight, aggregation of inorganic oxide fine particles occurs, and uniform resistance control of the entire intermediate layer may be hindered. A more preferable addition amount is 2 to 8% by weight.

The intermediate layer forming coating solution may further contain an antifoaming agent.
The antifoaming agent is intended to suppress foam by adding a very small amount to the intermediate layer forming coating solution.
When water is used as a solvent like the coating liquid for forming the intermediate layer, and particularly when a water-soluble resin is added, not only does the foaming by the dispersion and stirring during the preparation reduce the dispersion and stirring efficiency, Foaming during application may cause coating film defects. Antifoaming agents can suppress these problems.
Examples of the antifoaming agent include a silicone system, a surfactant system, a polyether system, a higher alcohol system, an emulsion system, and an oil compound system. Among these, an oil compound system containing silica powder having a strong foam breaking property is particularly preferable.

As an antifoamer, for example, product name: SN deformer 444, 470, 485, PC (polyether type), SN deformer 1311, 1316 (silicone type), SN deformer 777, 328, 480, H2 manufactured by San Nopco Co., Ltd. (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 emulsion such as DK Q1-1247 Etc.
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).
When the defoaming agent is 0.05 parts by weight or more, the electrical characteristics of the photoreceptor may be deteriorated, and when it is less than 0.0005 parts by weight, an effective foam breaking effect may not be obtained.

The coating solution for forming an intermediate layer 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 coating solution for forming the intermediate layer is dissolved in an aqueous medium containing a blocked isocyanate compound, a resin having an active hydrogen-containing group capable of reacting with an isocyanate group in the blocked isocyanate compound, inorganic oxide fine particles, and an electron transport agent. Alternatively, it can be prepared by dispersing.
The aqueous medium means water or a mixed medium of water and a hydrophilic organic solvent such as a lower alcohol. In the present invention, only water is preferable.
In order to disperse the components of the coating liquid for forming the intermediate layer, especially inorganic oxide fine particles in water, general dispersing machines such as paint shakers, ball mills, sand mills, ball mills, sand mills, attritors, vibration mills, ultrasonic dispersing machines A general grinder such as may be used.

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

In the photoreceptor of the present invention, at least an intermediate layer and an organic photosensitive layer are laminated in this order on a conductive support, and the intermediate layer supports the coating solution for forming an intermediate layer of the present invention. It is obtained by applying on the body and curing the obtained coating film.
Next, the photoreceptor of the present invention will be specifically described with reference to the drawings.
1 to 3 are schematic cross-sectional views showing the structure of the main part of the photoreceptor of the present invention.

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

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

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

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

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

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

In the case of a sheet, the application method of the intermediate layer forming coating solution is the Baker applicator method, bar coater method (for example, wire bar coater method), casting method, spin coating method, roll method, blade method, bead method, curtain method. In the case of a drum, a spray method, a vertical ring method, a dip coating method, and the like can be given.
As the coating method, an optimum method may be selected in consideration of the physical properties and productivity of the coating solution, and an immersion method, a blade coater method, and a spray method are particularly preferable.
The dip coating method is a method of forming a layer on the conductive support 1 by immersing the conductive support 1 in a coating tank filled with a coating solution and then pulling it up at a constant speed or a speed that changes sequentially. Since this method is relatively simple and excellent in terms of productivity and cost, it is widely used for manufacturing a photoreceptor. In addition, you may provide the coating liquid dispersion | distribution apparatus represented by the ultrasonic generator in order to stabilize the dispersibility of a coating liquid in the apparatus used for the dip coating method.

When the coating agent of the blocked isocyanate compound is removed, the resin having two or more active hydrogen-containing groups that can react with the isocyanate group in the blocked isocyanate compound starts an addition reaction with the isocyanate compound, and the coating is cured. Thermal curing is preferable.
The heat curing can be performed using a known apparatus such as a hot air drying furnace and a far-infrared drying furnace, and the conditions may be appropriately set depending on the type of block isocyanate compound or resin used, the mixing ratio, etc. The temperature is 110 to 150 ° C., preferably 130 to 150 ° C., and the time is about 10 minutes to 1 hour.

  The film thickness of the intermediate layer is larger than 10 μm and not larger than 50 μm. When the film thickness of the intermediate layer is 10 μm or less, it becomes difficult to inject charges into the photosensitive layer and to control minute black spots, and depending on the use environment, the chargeability may be significantly reduced. On the other hand, when the film thickness of the intermediate layer exceeds 50 μm, it is difficult to form a uniform coating film, and the sensitivity of the photoreceptor may be lowered, or the residual potential may be increased during use. A more preferable film thickness is larger than 10 μm and 30 μm or less.

The intermediate layer in the photoreceptor of the present invention may be not only a single layer but also a plurality of layers as long as it has a film thickness in the above range.
For example, a first intermediate layer (conductive layer) having a thickness of 10 to 40 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 intermediate having a thickness of 10 to 40 μm containing electrically conductive inorganic oxide fine particles Examples include a combination with a layer (moire prevention layer).

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

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

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

The charge generation layer is a chemical sensitizer, an optical sensitizer, an antioxidant, an ultraviolet absorber, a dispersion stabilizer, a sensitizer, a leveling agent, a plasticizer, as long as the preferable characteristics of the present invention are not impaired. An appropriate amount of one or more known additives selected from fine particles of inorganic compounds or organic compounds may be contained. These additives may be contained in the charge transport layer described later, and may be contained in both the charge generation layer and the charge transport layer. The chemical sensitizer and the optical sensitizer improve the sensitivity of the photoreceptor. In this way, increase in residual potential and fatigue due to repeated use are suppressed, and electrical durability is improved.

  Examples of chemical sensitizers include acid anhydrides such as succinic anhydride, maleic anhydride, phthalic anhydride, and 4-chloronaphthalic anhydride; cyano compounds such as tetracyanoethylene and terephthalmalondinitrile, 4-nitrobenzaldehyde, and the like. Aldehydes; anthraquinones such as anthraquinone and 1-nitroanthraquinone; polycyclic or heterocyclic nitro compounds such as 2,4,7-trinitrofluorenone and 2,4,5,7-tetranitrofluorenone; diphenoquinone compounds Examples thereof include electron-withdrawing materials and those obtained by polymerizing these electron-withdrawing materials.

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

Antioxidants can maintain sensitivity stability over a long period of time.
Antioxidants include phenolic antioxidants such as hindered phenols such as 2,6-di-t-butyl-4-methylphenol (2,6-di-t-butyl-p-cresol: BHT). , Amine antioxidants such as hindered amines, vitamin E, hydroquinone, paraphenylenediamine, arylalkanes and derivatives thereof, organic sulfur compounds, organic phosphorus compounds, etc., and these may be used alone or in combination of two or more. Can be used.
The addition amount of the antioxidant is preferably from 0.1 to 40 parts by weight, particularly preferably from 0.5 to 15 parts by weight, based on 100 parts by weight of the charge generation material.
If the addition amount of the antioxidant is less than 0.1 parts by weight, a sufficient effect for improving the stability of the coating solution and improving the durability of the photoreceptor may not be obtained. On the other hand, if the amount of the antioxidant added exceeds 40 parts by weight, the photoreceptor characteristics may be adversely affected.

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

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

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

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

  Examples of the organic solvent include aromatic hydrocarbons such as 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.

Prior to dissolving or dispersing the constituent materials in the resin solution, the charge generating material may be pre-ground.
The preliminary pulverization can be performed using, for example, a general pulverizer such as a ball mill, a sand mill, an attritor, a vibration mill, or an ultrasonic disperser.
The dissolution or dispersion of the constituent materials in the resin solution can be performed using, for example, a general disperser such as a paint shaker, a ball mill, or a sand mill. At this time, it is preferable to appropriately set the dispersion condition so that impurities are generated from the container and the members constituting the disperser due to wear and the like and are not mixed into the coating liquid.
The application method of the charge generation layer forming coating solution is a baker applicator method, a bar coater method, a casting method, a spin coating method, a roll method, a blade method or the like in the case of a sheet, and a spray method or a vertical ring method in the case of a drum. And a dip coating method.

Although it will not specifically limit if the temperature in the drying process of a coating film is the temperature which can remove the used organic solvent, 50-140 degreeC is suitable and 80-130 degreeC is especially preferable.
When the drying temperature is less than 50 ° C., the drying time may be long. On the other hand, if the drying temperature exceeds 140 ° C., the electrical characteristics during repeated use of the photoreceptor may deteriorate and the resulting image may deteriorate.
The thickness of the charge generation layer is not particularly limited, but is preferably 0.05 to 5 μm, particularly preferably 0.1 to 1 μm. When the thickness of the charge generation layer is less than 0.05 μm, the light absorption efficiency is lowered, and the sensitivity may be lowered. On the other hand, when the film thickness of the charge generation layer exceeds 5 μm, charge transport inside the charge generation layer becomes a rate-determining step in the process of erasing charges on the surface of the photoreceptor, and the sensitivity may be lowered.

[Charge transport layer 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, poly-N-vinylcarbazole and derivatives thereof, poly-γ-carbazolylethyl glutamate and derivatives thereof, pyrene-formaldehyde condensates and derivatives thereof, polyvinylpyrene, polyvinylphenanthrene, oxazole derivatives, oxadiazole derivatives Imidazole derivatives, 9- (p-diethylaminostyryl) anthracene, 1,1-bis (4-dibenzylaminophenyl) propane, styrylanthracene, styrylpyrazoline, pyrazoline derivatives, phenylhydrazones, hydrazone derivatives, triphenylamine series Electron donating substances such as compounds, tetraphenyldiamine compounds, triphenylmethane compounds, stilbene compounds, azine compounds having a 3-methyl-2-benzothiazoline ring;
Fluorenone derivatives, dibenzothiophene derivatives, indenothiophene derivatives, phenanthrenequinone derivatives, indenopyridine derivatives, thioxanthone derivatives, benzo [c] cinnoline derivatives, phenazine oxide derivatives, tetracyanoethylene, tetracyanoquinodimethane, promanyl, chloranil And electron accepting substances 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 becomes high, and sufficient sensitivity may not be obtained.
On the other hand, when the ratio E / B exceeds 10/12, the printing durability of the charge transport layer and the durability of the photoreceptor may be lowered.

As the binder resin, one or more of the same binder resins as those contained in the charge generation layer can be used.
Among these resins, polycarbonate-based resins, polyarylate resins and polystyrene resins are photochemically stable, excellent in compatibility with charge transport materials, and have a volume resistance of 10 ¹³ Ω or more. It is preferable because it is excellent in electrical insulation and has excellent film forming properties and potential characteristics.
The charge transport layer may contain an appropriate amount of the same additive as that contained in the charge generation layer, if necessary, within the range not impairing the effects of the present invention.

The charge transport layer is prepared by dissolving or dispersing a charge transport material, a binder resin and, if necessary, other additives in an appropriate organic solvent to prepare a coating solution for forming a charge transport layer. It can be formed by applying to the surface and then drying to remove the organic solvent. More specifically, for example, a charge transport layer forming 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.
Other processes and conditions are in accordance with the formation of the charge generation layer.
Although the film thickness of a charge transport layer is not specifically limited, 10-60 micrometers is preferable and 10-40 micrometers is especially preferable. If the thickness of the charge transport layer is less than 10 μm, the charge retention ability may be reduced. Conversely, if the thickness of the charge transport layer is more than 60 μm, the sharpness is reduced and the residual potential is increased. Image degradation may occur significantly.

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

  The film thickness of the single-layer type photosensitive layer is not particularly limited, but is preferably 10 to 100 μm, and particularly preferably 15 to 50 μm. When the film thickness of the single-layer type photosensitive layer is less than 10 μm, the charge holding ability on the surface of the photoreceptor may be lowered, and when the film thickness of the single-layer type photosensitive layer exceeds 100 μm, the productivity may be lowered. is there.

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

  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 protective layer is less than 0.5 μm, the surface resistance of the photoreceptor is inferior and the durability may be insufficient. Conversely, if the thickness exceeds 10 μm, the resolution of the photoreceptor may be reduced. .

  The image forming apparatus of the present invention comprises: the photosensitive member of the present invention; a charging unit that charges the electrophotographic photosensitive member; and exposure that forms an electrostatic latent image by exposing the charged electrophotographic photosensitive member. Developing means for developing the electrostatic latent image to form a toner image, transfer means for transferring the toner image 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 electrophotographic photosensitive member, and a neutralizing unit that neutralizes surface charges remaining on the electrophotographic photosensitive member.

The image forming apparatus of the present invention will be described with reference to the drawings, but is not limited to the following description.
FIG. 4 is a schematic side view showing the configuration of the image forming apparatus of the present invention.
The image forming apparatus 20 in FIG. 4 includes a photoreceptor 21 of the present invention (for example, one of the photoreceptors in FIGS. 1 to 3), a charging unit (charger) 24, an exposure unit 28, and a developing unit ( 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 340 mm, and a thickness of 0.8 mm was used to produce the photoconductor of FIG.
First, zinc oxide (number average primary particle size: spinning shape, 30 × 90 nm, manufactured by Sakai Chemical Industry Co., Ltd., product name: STR-60) as inorganic oxide fine particles, and aqueous as a resin 8.4 parts by weight of a polyacryl polyol (solid content: 45%, OH value: 80, manufactured by DIC Corporation, product name: Burnock WE-300) and a blocked isocyanate compound (solid content: 40%, NCO content: 5 .4%, Mitsui Chemicals Polyurethanes Co., Ltd., product name: Takenate WB-920) 4.2 parts by weight and antifoaming agent (oil compound, San Nopco Co., Ltd., product name: SN deformer 470) 0.5 wt. Part, 0.5 parts by weight of a dispersion stabilizer (manufactured by San Nopco, product name: Roma PWA-40), and a naphthalenecarboxylic acid derivative represented by the following (formula-2) as an electron transport agent And .3 parts by weight, was added to the aqueous 69 parts by weight, and 6 hours for performing dispersion treatment using a paint shaker, and the coating solution 3Kg intermediate layer formation was prepared.

The isocyanate group (H) of the blocked isocyanate compound is 1.0 molar ratio (H / B) to the active hydrogen-containing group (B) of the resin, and the inorganic oxide fine particles (P) are crosslinked resin (block isocyanate). The weight ratio (P / R) was 6/4 with respect to the sum of compounds and resins: R).
The obtained coating solution for forming an intermediate layer is filled in a coating tank, dipped in a conductive support, and then pulled up. The obtained coating film is dried and cured at a temperature of 150 ° C. for 30 minutes to form an intermediate layer having a thickness of 20 μm. Formed.

  Next, 2 parts by weight of Y-type oxotitanium phthalocyanine (manufactured by Sanyo Dye Co., Ltd.) as a charge generating substance, and polyvinyl butyral resin (product name: S-REC B BM-S) as a binder resin 1 part by weight and 97 parts by weight of methyl ethyl ketone as an organic solvent were mixed and dispersed using a paint shaker to prepare 3 kg of a coating solution for forming a charge generation layer. This charge generation layer forming coating solution was applied onto the previously formed intermediate layer by the same dip coating method as that for the intermediate layer, and naturally dried to form a charge generation layer having a thickness of 0.4 μm.

Next, 10 parts by weight of a compound represented by the following structural formula (3) as a charge transport material, 18 parts by weight of a polycarbonate resin (product name: Iupilon Z400, manufactured by Mitsubishi Engineering Plastics) as a binder resin, 0.56 parts 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 3 kg of a charge transport layer forming coating solution. This charge transport layer forming coating solution is applied onto the previously formed charge generation layer by the same dip coating method as that for the intermediate layer and dried at a temperature of 130 ° C. for 1 hour to form a charge transport layer having a thickness of 15 μm. did.
The photoreceptor of Example 1 was produced as described above.

(Example 2)
An electrophotographic photoreceptor of Example 2 was produced in the same manner as in Example 1 except that the film thickness after the drying step of the coating solution for forming an intermediate layer was 12 μm.
(Example 3)
An electrophotographic photoreceptor of Example 3 was produced in the same manner as in Example 1 except that the film thickness after the drying step of the coating solution for forming an intermediate layer was 28 μm.
Example 4
An electrophotographic photoreceptor of Example 5 was produced in the same manner as in Example 1 except that the film thickness after the drying step of the coating solution for forming an intermediate layer was 40 μm.
(Example 5)
An electrophotographic photoreceptor of Example 6 was produced in the same manner as in Example 1 except that the compound represented by (Formula 1-1) was used as the electron transporting agent contained in the intermediate layer.
(Example 6)
An electrophotographic photoreceptor of Example 6 was produced in the same manner as in Example 1 except that the compound represented by (Formula 1-7) was used as the electron transporting agent contained in the intermediate layer.

(Comparative Example 1)
12 parts by weight of zinc oxide (manufactured by Sakai Chemical Industry Co., Ltd., product name: STR-60) as inorganic oxide fine particles and butyral resin (product name BM-1 produced by Sekisui Chemical Co., Ltd.) as a resin ) 3.6 parts by weight, blocked isocyanate compound (solid content: 40%, NCO content: 11.2%, manufactured by Sumitomo Bayer Urethane Co., Ltd., product name Sumijoule 3175), 4.0 parts by weight, and electron transport agent As above, 1.3 parts by weight of the naphthalenecarboxylic acid derivative represented by the above (formula-2) was added to 60 parts by weight of methyl ethyl ketone and dispersed for 6 hours using a paint shaker to prepare 3 kg of an intermediate layer forming coating solution. An electrophotographic photosensitive member of Comparative Example 1 was prepared in the same manner as in Example 1 except that this coating solution was used, and the film thickness of the intermediate layer, the charge generation layer, and the charge transport layer were all the same as in Example 1.

(Comparative Example 2)
The amount of water added to the intermediate layer forming coating solution in Example 1 was changed from 69 parts by weight to 100 parts by weight, and the film thickness after the drying step of the intermediate layer forming coating solution was changed to 0.5 μm. Produced the electrophotographic photosensitive member of Comparative Example 2 in the same manner as in Example 1.
(Comparative Example 3)
The same method as in Example 1 except that the amount of water added to the coating solution for forming the intermediate layer in Example 1 was changed from 69 parts by weight to 50 parts by weight, and the film thickness after the drying step was changed to 55 μm. Thus, an electrophotographic photosensitive member of Comparative Example 3 was produced.

(Comparative Example 4)
12 parts by weight of zinc oxide (manufactured by Sakai Chemical Industry Co., Ltd., product name: STR-60) as inorganic oxide fine particles, and aqueous polyacrylic polyol (solid content: 45%, OH value: 80, DIC) as resin 8.4 parts by weight manufactured by Co., Ltd., product name: Burnock WE-300, and blocked isocyanate compound (solid content: 40%, NCO content: 5.4%, manufactured by Mitsui Chemicals Polyurethanes, Inc., product name: Takenate WB) -920) 4.2 parts by weight and defoaming agent (oil compound, San Nopco, product name: SN deformer 470) 0.5 parts by weight, dispersion stabilizer (San Nopco, product name: Roma PWA) -40) 0.5 part by weight was added to 100 parts by weight of water and dispersed for 6 hours using a paint shaker to prepare 3 kg of an intermediate layer forming coating solution (H / B = 1.0, P / R = 6/4).

The obtained coating solution for forming an intermediate layer is filled in a coating tank, and the same conductive support as in Example 1 is immersed and then pulled up. The resulting coating film is dried and cured at a temperature of 150 ° C. for 30 minutes to obtain a film thickness. A 1 μm intermediate layer was formed.
The electrophotographic photosensitive member of Comparative Example 4 was prepared in the same manner as in Example 1 except that the intermediate layer was used, except that the charge generation layer and the charge transport layer had the same configuration.

(Comparative Example 5)
As a resin, 8.4 parts by weight of an aqueous polyacrylic polyol (solid content: 45%, OH value: 80, manufactured by DIC Corporation, product name: Burnock WE-300) and a blocked isocyanate compound (solid content: 40%, NCO content: 5.4%, Mitsui Chemicals Polyurethane Co., Ltd., product name: Takenate WB-920) 4.2 parts by weight and antifoaming agent (oil compound, San Nopco Co., Ltd., product name: SN deformer 470 ) 0.5 part by weight, 0.5 parts by weight of a dispersion stabilizer (manufactured by San Nopco, product name: Roma PWA-40) is added to 100 parts by weight of water and dispersed for 6 hours using a paint shaker, and the intermediate layer 3 kg of a coating solution for forming was prepared (H / B = 1.0).

The obtained coating solution for forming an intermediate layer is filled in a coating tank, and the same conductive support as in Example 1 is immersed and then pulled up. The resulting coating film is dried and cured at a temperature of 150 ° C. for 30 minutes to obtain a film thickness. A 1 μm intermediate layer was formed.
The electrophotographic photosensitive member of Comparative Example 5 was produced in the same manner as in Example 1 except that the intermediate layer was used, except that the charge generation layer and the charge transport layer had the same configuration.

In addition, control of the film thickness of the intermediate | middle layer in the said Example and comparative example was implemented by controlling the coating speed at the time of dip coating.

[Evaluation]
1. Initial characteristic evaluation The photoconductors of Examples 1 to 7 and Comparative Examples 1 to 5 manufactured as described above were modified with a scorotron charger and a laser complex machine (model: MX-4500N, manufactured by Sharp Corporation). 4 was mounted on an image forming apparatus having the same structure as that of No. 4, and the characteristics of each electrophotographic photosensitive member were evaluated.
Specifically, the surface potential V0 of each electrophotographic photosensitive member when the electrophotographic photosensitive member is charged with a scorotron charger having a grid applied voltage of −650 V in a normal temperature and normal humidity (25 ° C., 50% RH) environment. [V] was measured. Next, the surface potential: VL [V] of each electrophotographic photosensitive member when the entire surface was irradiated with a 780 nm laser beam (solid image formation) was measured.

2. Stability evaluation against changes in usage environment The above operation was performed in the same manner except that the operation was performed under two different environments of room temperature and low humidity (25 ° C., 5% RH) and room temperature and high humidity (25 ° C., 85% RH). Then, the potential V0 and the potential VL after the exposure were measured. Then, fluctuation amounts (ΔV0, ΔVL) of the values of the potential V0 and the potential VL between these different environments were measured, and the stability of each electrophotographic photosensitive member was evaluated against changes in the usage environment.

3. Characteristic evaluation after repeated use Using the A4 original with a test chart (printing rate: 5%) on the above-mentioned multi-function machine, repeated real-time shooting 10,000 times in a normal temperature and humidity environment, and then the above V0 and VL Each electrophotographic photoreceptor was measured.

4). Image quality evaluation after repeated use.
The image quality after printing 10,000 sheets after repeated use was evaluated according to the following criteria.
“No abnormality”; good image quality is obtained; good image quality “fogging occurs”; fine black spots are seen on the paper surface, but there is no problem in practical use. Black spot generation ratio: Less than 5% of the total print area ratio.
“Spot generation”: A large black spot is observed on the paper, which causes a problem in use. Black spot generation ratio: 5% or more of the total print area ratio.
The results for the four evaluation items are shown in Table 1.

Table 1 shows the following.
The photoconductors of the examples are obtained from an intermediate layer forming coating solution containing an isocyanate thermosetting resin that can be dissolved / dispersed in an aqueous medium, inorganic oxide fine particles, and an electron transport agent. The photoreceptors of these examples were clearly superior in the uniformity of the intermediate layer thickness as compared with the photoreceptors using the intermediate layer forming coating solution dissolved / dispersed in the organic solvent system shown in Comparative Example 1. . As a result, the photoreceptors of Examples were superior to Comparative Example 1 in chargeability and stability.
Further, in the photoconductors of Comparative Examples 2 to 4 having an intermediate layer having a thickness of 10 μm or less and greater than 50 μm, the V0 or VL stability is insufficient, and desired photoconductor characteristics cannot be obtained. It became. In Comparative Example 5, despite the thin film thickness of the intermediate layer of 1 μm, the sensitivity degradation that seems to be due to the trap inside the intermediate layer was so great that it was not possible to reach the actual shooting test. In the photoconductor of the example provided with an intermediate layer having a film thickness of greater than 10 μm and less than 50 μm, the chargeability and stability were superior to those of Comparative Examples 2-5.

Furthermore, as shown in Examples 1 to 4, the photoreceptor characteristics are affected by the thickness setting of the intermediate layer. That is, when it is made thinner, VL and its stability are improved, but the stability of V0 is lowered. On the other hand, when the thickness is increased, the stability of the charging property / V0 is improved, but a tendency to increase VL is observed due to the fatigue of actual shooting.
Further, in the case of Example 5 or Example 6 using a specific anthraquinone derivative or alizarin as an electron transport agent, the V0 and VL stability against the environmental change is improved, and the stability of electrical or image quality after actual shooting is improved. Also good results were obtained.

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

Explanation of symbols

1 conductive support 2 intermediate layer (undercoat layer)
DESCRIPTION OF SYMBOLS 3 Charge generation layer 4 Charge transport layer 5 Laminated type photosensitive layer 5 'Single layer type photosensitive layer 20 Image forming apparatus 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 (7)

An electrophotographic photoreceptor in which an intermediate layer and an organic photosensitive layer are sequentially laminated on a conductive substrate,
In the intermediate layer, at least a blocked isocyanate compound, a resin having an active hydrogen-containing group capable of reacting with an isocyanate group in the blocked isocyanate compound, inorganic oxide fine particles, and an electron transport agent are dissolved or dispersed in water . An electrophotographic photosensitive member obtained by applying and heat-curing a coating solution for forming an intermediate layer and having a thickness of more than 10 μm and not more than 50 μm.   The electrophotographic photosensitive member according to claim 1, wherein the intermediate layer has a thickness greater than 10 μm and not greater than 30 μm.   The electrophotographic photosensitive member according to claim 1, wherein the electron transfer agent is an anthraquinone derivative.   The electrophotographic photoreceptor according to claim 3, wherein the anthraquinone derivative is alizarin.   The electrophotographic photosensitive member according to claim 1, wherein the inorganic oxide fine particles are fine particles of titanium oxide or zinc oxide.   The electrophotographic photosensitive member according to claim 1, wherein the inorganic oxide fine particles are fine particles having an average primary particle size of 20 to 500 nm.   An electrophotographic photosensitive member according to any one of claims 1 to 6, a charging means for charging the electrophotographic photosensitive member, and an electrostatic latent image formed by exposing the charged electrophotographic photosensitive member. An exposure means for forming the toner, a developing means for developing the electrostatic latent image to form a toner image, a transfer means for transferring the toner image onto the recording material, and the transferred toner image on the recording material. At least a fixing unit that forms an image by fixing the toner onto the electrophotographic photosensitive member, a cleaning unit that removes and collects toner remaining on the electrophotographic photosensitive member, and a neutralizing unit that neutralizes surface charge remaining on the electrophotographic photosensitive member. An image forming apparatus.

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