JP2010243984A - Electrophotographic photoconductor, image forming method, image forming device and process cartridge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic photoconductor which is suitable for image forming to form a high-density latent image on an organic photoconductor by exposure with light of the wavelength range of 350-500 nm and which is excellent particularly in interference fringe resistance on an obtained electrophotographic image and is excellent in black spot resistance, residual potential resistance and environmental memory resistance even when image blur is improved; and to provide an image forming method using the electrophotographic photoconductor, an image forming device and a process cartridge. <P>SOLUTION: The electrophotographic photoconductor has an intermediate layer having metal oxide particles and a photoconductor layer, which are sequentially laminated, on a conductive support body, where the metal oxide particles are coated by pigment having an absorption maximum in the wavelength range of 350-500 nm. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an electrophotographic photosensitive member, an image forming method, an image forming apparatus, and a process cartridge used for electrophotographic image formation, and more specifically, to electrophotographic image formation used in the fields of copying machines and printers. The present invention relates to an electrophotographic photoreceptor used, an image forming method, an image forming apparatus, and a process cartridge.

  In recent years, opportunities for using electrophotographic copying machines and printers in the fields of printing and color printing are increasing. In the fields of printing and color printing, there is a strong tendency to demand high-quality digital monochrome images or color images. In response to such a demand, it has been proposed to form a high-definition digital image using a short-wavelength laser beam as an exposure light source (Patent Documents 1 and 2). However, even if the short-wavelength laser light is used to reduce the dot diameter of the exposure and a fine electrostatic latent image is formed on the electrophotographic photosensitive member, the finally obtained electrophotographic image has sufficient high image quality. The current situation has not been achieved.

  This is because the problem newly generated in an image obtained by image exposure with a short wavelength cannot be sufficiently dealt with.

  That is, as an electrophotographic photoreceptor, an organic photoreceptor developed for a conventional long wavelength laser (hereinafter, also simply referred to as a photoreceptor) is an image in which the exposure dot diameter is reduced by using a short wavelength laser beam or the like. When exposure is performed, image irregularities such as interference fringes (moire) due to laser exposure, which are not conspicuous, appear in a conventional image with a large dot diameter, and reproducibility of a fine dot image is not achieved.

  As a conventional technique for preventing interference fringes (moire) due to laser exposure, a technique in which metal oxide fine particles typified by titanium oxide are dispersed and contained in the intermediate layer of the photoreceptor, and light is appropriately scattered in the intermediate layer. Have been actively studied (Patent Document 3, Patent Document 4).

  However, when the content of titanium oxide is increased in order to improve the moire resistance, the titanium oxide particles partially aggregate in the intermediate layer or form a bridging structure in the layer. When used, there is a problem in that charges leak through the portion and image results such as black spots are likely to occur. As countermeasures against this problem, studies have been made on improving the electric resistance by performing organic or inorganic surface treatment on the surface of titanium oxide or the like, and increasing the resistance of the binder resin in the intermediate layer.

  However, the improvement in electrical resistance due to the surface treatment of titanium oxide, etc., newly increases residual potential in the intermediate layer and environmental memory (image unevenness due to partial accumulated charges generated when temperature and humidity changes are large). Resolve the problem of high moiré resistance and reduction of black spot defects, increase in residual potential, environmental memory, etc. in the electrophotographic photoreceptor used in the image forming apparatus using the coherent light source. That left a big challenge.

JP 2000-250239 A JP 2000-105479 A Japanese Patent Laid-Open No. 4-303846 JP-A-8-328283

  The present invention has been made in view of the above problems, and an object of the present invention is to form a high-density electrostatic latent image on an organic photoreceptor by exposure to light having a wavelength in the range of 350 to 500 nm. The electrophotographic image sensor is suitable for forming images and has excellent interference fringe resistance, and improved image blurring, but also has excellent black spot resistance, residual potential resistance and environmental memory resistance. An object is to provide an image forming method, an image forming apparatus, and a process cartridge using the electrophotographic photosensitive member.

  The above object of the present invention can be achieved by the following constitution.

  1. In an electrophotographic photoreceptor having an intermediate layer containing metal oxide particles and a photosensitive layer sequentially laminated on a conductive support, the metal oxide particles are dyes having an absorption maximum in a wavelength region of 350 to 500 nm. An electrophotographic photosensitive member characterized by being coated.

  2. 2. The electrophotographic photosensitive member according to 1 above, wherein the metal oxide particles are titanium oxide.

  3. 3. The electrophotographic photoreceptor according to 1 or 2, wherein the dye has an acidic group in the molecule.

  4). 4. The electrophotographic photosensitive member according to any one of items 1 to 3, wherein the photosensitive layer contains a compound represented by the following general formula (1) or (2).

[Wherein, R ₁ and R ₂ each independently represents an alkyl group or an alkoxy group having 1 to 5 carbon atoms. R ₃ and R ₄ each independently represents a substituted or unsubstituted alkyl group or alkoxy group having 1 to 5 carbon atoms. n represents an integer of 0 to 2, and o represents an integer of 0 to 3. l and m each independently represents an integer of 0 to 5. A, B, C and D each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, an alkoxy group or an aryl group. However, A, B, C and D are not simultaneously hydrogen atoms. ]

[Wherein, R ₅ , R ₆ , R ₇ , and R ₈ each independently represents an alkyl group or an alkoxy group having 1 to 5 carbon atoms. p represents an integer of 0 to 5, q represents an integer of 0 to 4, r represents an integer of 0 to 2, and s represents an integer of 0 to 3. R ₉ and R ₁₀ each independently represents an alkyl group or an aryl group, and R ₉ and R ₁₀ may combine to form a ring structure. A, B, C and D have the same meanings as A, B, C and D in the general formula (1). However, A, B, C and D are not simultaneously hydrogen atoms. ]
5). 5. The electrophotographic photosensitive member according to any one of items 1 to 4, wherein the electrophotographic photosensitive member has a surface protective layer on the photosensitive layer.

  6). A charging step for applying a uniform charging potential on the electrophotographic photosensitive member, and exposing the electrostatic latent image on the electrophotographic photosensitive member having the charging potential with light having a wavelength in the range of 350 to 500 nm. In the image forming method comprising an exposure step of forming, a developing step of developing the electrostatic latent image into a toner image, and a step of transferring the toner image to a transfer medium, An image forming method using the electrophotographic photosensitive member according to claim 1.

  7). 7. An image forming apparatus using the image forming method described in 6 above.

  8). 6. A process cartridge used in the image forming apparatus described in item 7 comprises at least one of the electrophotographic photosensitive member described in any one of items 1 to 5 and at least one of a charging unit, an image exposing unit, and a developing unit. And a process cartridge configured to be removable from and into the image forming apparatus.

  According to the present invention, it is suitable for image formation in which a high-density electrostatic latent image is formed on an organic photoreceptor by exposure with light having a wavelength in the range of 350 to 500 nm. It is possible to provide an electrophotographic photoreceptor excellent in interference fringe resistance and improved image blur, and excellent in black spot resistance, residual potential resistance and environmental memory resistance. The used image forming method, image forming apparatus, and process cartridge can be provided.

1 is a schematic view in which functions of an image forming apparatus of the present invention are incorporated. 1 is a cross-sectional configuration diagram of a color image forming apparatus showing an embodiment of the present invention. 1 is a cross-sectional view of a color image forming apparatus using an organic photoreceptor of the present invention.

  Hereinafter, although the form for implementing this invention is demonstrated, this invention is not limited to these.

  Hereinafter, the electrophotographic photoreceptor of the present invention will be described in detail.

  The present invention relates to an electrophotographic photosensitive member having an intermediate layer containing metal oxide particles and a photosensitive layer sequentially laminated on a conductive support, wherein the metal oxide particles have an absorption maximum in a wavelength region of 350 to 500 nm. It is characterized by being coated with a pigment having

  In the present invention, the intermediate layer contains metal oxide particles coated with a dye having an absorption maximum in the wavelength region of 350 to 500 nm, so that the light is exposed to light having a wavelength in the range of 350 to 500 nm. Suitable for image formation to form a high-density electrostatic latent image on an organophotoreceptor, and the resulting electrophotographic image is particularly resistant to interference fringes and has improved image blur, but is also resistant to black spots An electrophotographic photoreceptor excellent in residual potential resistance and environmental memory resistance can be obtained.

  In the present invention, metal oxide particles coated with a dye having an absorption maximum in a wavelength region of 350 to 500 nm are contained in the intermediate layer.

(Metal oxide particles)
The metal oxide particles used in the intermediate layer of the present invention are magnesium oxide, zinc oxide, lead oxide, aluminum oxide, tantalum oxide, indium oxide, bismuth oxide, yttrium oxide, cobalt oxide, copper oxide, manganese oxide, selenium oxide, Examples include metal oxide particles such as iron oxide, zirconium oxide, germanium oxide, tin oxide, titanium oxide, niobium oxide, molybdenum oxide, and vanadium oxide. Among them, metal oxide particles such as titanium oxide, alumina, and tin oxide are exemplified. Is preferred.

  Furthermore, the metal oxide particles used in the present invention are preferably those produced by a known method, for example, a general production method such as a gas phase method, a chlorine method, a sulfuric acid method, a plasma method, or an electrolytic method.

  The number average primary particle size of the metal oxide particles used in the present invention is preferably in the range of 1 to 300 nm. Especially preferably, it is 3-100 nm.

  The number average primary particle size of the metal oxide particles is a photographic image (excluding aggregated particles) taken with a scanning electron microscope (manufactured by JEOL Ltd.) with a magnification of 10000 times, and 300 particles randomly taken by a scanner. A) automatic image processing analyzer LUZEX AP (Nireco Corp.) software version Ver. The number average primary particle size was calculated using 1.32.

  The molar extinction coefficient ε is defined as follows.

When the incident light is I ₀ and the transmitted light is I, the absorbance (A) is defined as A = log (I ₀ / I). The relationship between absorbance A, molar extinction coefficient ε, solution concentration c (mol / l), and length d (cm) is defined below.

A = εcd
In the above, the light absorbency was measured using the spectrophotometer of U-3500 (Hitachi Ltd.).

(Dye)
The dye used in the intermediate layer of the present invention is selected from a group of dyes having an absorption maximum at 350 nm to 500 nm, but preferably has an acidic group in the molecule. The dye having an acidic group is immobilized on the surface of the metal oxide fine particle by chemical adsorption, and a high coverage can be obtained.

  Examples of pigments used in the present invention include nitroso dyes, nitro dyes, azo dyes, stilbene dyes, diphenylmethane dyes, triarylmethane dyes, acridine dyes, quinoline dyes, methine dyes, polymethine dyes, thiazole dyes, indamine dyes, and indophenol dyes. , Indophenol blue, azine dye, oxazine dye, thiazine dye, sulfur dye, aminoketone dye, oxyketone dye, anthraquinone dye, indigoid dye, phthalocyanine dye, etc. A solubilized compound group can be used. Further, a pigment obtained by aggregating these dyes may be used.

  In the present invention, the intermediate layer contains metal oxide particles coated with a dye having an absorption maximum in a wavelength region of 350 to 500 nm.

  The coating of the metal oxide particles with the dye can be easily performed by, for example, immersing the metal oxide particles in the dye solution.

  For the measurement of the maximum absorbance of the intermediate layer in the wavelength region of 350 to 500 nm, the absorbance of the intermediate layer sample is measured with a spectrophotometer to obtain the molar extinction coefficient at the absorption maximum wavelength of 350 to 500 nm. Absorbance is measured using a spectrophotometer of U-3500 (Hitachi).

  As the dye having an absorption maximum in the wavelength range of 350 to 420 nm, squarylium, azomethine, cyanine, merocyanine, oxonol, anthraquinone, azo, and benzylidene compounds and their metal chelate compounds are preferably used. It is done.

  Specific examples of the dye having an absorption maximum in the wavelength range of 350 to 450 nm are shown below, but the present invention is not limited thereto.

  As the dye having an absorption maximum in the wavelength range of 480 to 500 nm, squarylium, azomethine, cyanine, oxonol, anthraquinone, azo or benzylidene dye compounds are preferably used. As the azo dye, many azo dyes described in British Patent Nos. 539703, 575691, U.S. Pat. No. 2,956,879, Hiroshi Horiguchi, “Review Synthetic Dye”, Sankyo Publishing, etc. can be used. it can.

  Specific examples of the dye having an absorption maximum in the wavelength range of 480 to 500 nm are shown below, but the present invention is not limited thereto.

  The electrophotographic photoreceptor of the present invention is an organic photoreceptor, and the configuration of the organic photoreceptor of the present invention will be described below.

  In the present invention, the organic photoconductor means an electrophotographic photoconductor formed by giving an organic compound at least one of a charge generation function and a charge transport function indispensable for the configuration of the electrophotographic photoconductor. All known organic photoconductors such as a photoconductor composed of an organic charge generating material or an organic charge transport material, a photoconductor composed of a polymer complex with a charge generating function and a charge transport function are contained.

The constitution of the organophotoreceptor of the present invention is not particularly limited as long as the intermediate layer contains metal oxide particles coated with a dye having an absorption maximum in the wavelength region of 350 to 500 nm. For example, the following is shown. Such as:
1) A structure in which a charge generation layer and a charge transport layer are sequentially laminated as a photosensitive layer on a conductive support;
2) A structure in which a charge generation layer, a first charge transport layer, and a second charge transport layer are sequentially laminated as a photosensitive layer on a conductive support;
3) A structure in which a single layer containing a charge transport material and a charge generation material is formed as a photosensitive layer on a conductive support;
4) A structure in which a charge transport layer and a charge generation layer are sequentially laminated as a photosensitive layer on a conductive support;
5) A structure in which a surface protective layer is further formed on the photosensitive layer of the photoreceptors 1) to 4) above.

  The organophotoreceptor of the present invention may have any of the above configurations.

  In the present invention, the configuration 2) is most preferably used. That is, the above-described configurations 1 to 4 in which the photosensitive layer has a charge generation layer containing a charge generation material and a charge transport layer containing a charge transport material are preferable embodiments.

  Note that, even if the organic photoreceptor of the present invention has any of the above-described structures, an undercoat layer (intermediate layer) is formed prior to forming the photosensitive layer on the conductive support.

  Next, the layer structure of the organic photoreceptor will be described focusing on the structure of 2) above.

(Conductive support)
The conductive support used for the photosensitive member may be either a sheet or a cylinder, but a cylindrical conductive support is more preferable for designing an image forming apparatus compactly.

  Cylindrical conductive support means a cylindrical support necessary for forming an endless image by rotating. Conductivity is within a range of 0.1 mm or less in straightness and 0.1 mm or less in deflection. A support is preferred. Exceeding the straightness and shake range makes it difficult to form a good image.

As the conductive material, a metal drum such as aluminum or nickel, a plastic drum deposited with aluminum, tin oxide, indium oxide or the like, or a paper / plastic drum coated with a conductive substance can be used. The conductive support preferably has a specific resistance of 10 ³ Ωcm or less at room temperature. The conductive support according to the present invention is most preferably an aluminum support. As the aluminum support, one in which components such as manganese, zinc, magnesium and the like are mixed in addition to the main component aluminum is also used.

(Middle layer)
In the present invention, an intermediate layer is provided between the conductive support and the photosensitive layer.

  As described above, the intermediate layer is characterized by containing metal oxide particles coated with a dye having an absorption maximum in the wavelength region of 350 to 500 nm of the present invention. Played.

  In the present invention, the maximum absorbance in the wavelength region of 350 to 500 nm of the intermediate layer is preferably 0.05 / μm to 0.50 / μm, more preferably 0.10 / μm to 0.45 / μm. It is.

  For the measurement of the maximum absorbance of the intermediate layer in the wavelength region of 350 to 500 nm, the absorbance of the intermediate layer sample is measured with a spectrophotometer to obtain the maximum absorbance in the wavelength region of 350 to 500 nm. Absorbance is measured using a spectrophotometer of U-3500 (Hitachi).

(Binder resin)
Further, as the binder resin for dispersing the metal oxide particles of the present invention and forming the layer structure of the intermediate layer, polyamide resin, alkyd resin, resol type phenol resin are used in order to obtain good dispersibility of the metal oxide particles. Etc. are preferred. Of these, the polyamide resin is preferably an alcohol-soluble polyamide resin. As the binder resin for the intermediate layer of the organic photoreceptor, a resin having excellent solvent solubility is required in order to form the intermediate layer with a uniform film thickness. As such alcohol-soluble polyamide resins, copolymerized polyamide resins and methoxymethylated polyamide resins composed of a chemical structure with few carbon chains between amide bonds, such as 6-nylon, are known. And the following polyamides can also be preferably used.

  The molecular weight of the polyamide resin is preferably 5,000 to 80,000, more preferably 10,000 to 60,000 in terms of number average molecular weight. A number average molecular weight of 5,000 or more is preferable because the uniformity of the film thickness of the intermediate layer is maintained and the effects of the present invention are exhibited. On the other hand, if it is 80,000 or less, the solvent solubility of the resin is maintained, and the generation of aggregated resin and black spots in the intermediate layer is suppressed, which is preferable from the viewpoint of dot images.

  A part of the polyamide resin is already available on the market. For example, the polyamide resin is sold under the trade names such as Vestamelt X1010 and X4685 manufactured by Daicel Degussa Co., Ltd., and can be prepared by a general polyamide synthesis method. An example of synthesis is given below.

  Solvents for dissolving the polyamide resin or alkyd resin to prepare a coating solution include alcohols having 2 to 4 carbon atoms such as ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol, t-butanol, sec-butanol and the like. Is preferable, and is excellent in terms of solubility of polyamide and applicability of the prepared coating solution. These solvents are 30 to 100% by mass, preferably 40 to 100% by mass, and more preferably 50 to 100% by mass in the total solvent. Examples of co-solvents that can be used in combination with the above-mentioned solvent to obtain preferable effects include methanol, benzyl alcohol, toluene, methylene chloride, cyclohexanone, and tetrahydrofuran.

  In the present invention, the thickness of the intermediate layer is preferably 0.5 to 10 μm. When the thickness of the intermediate layer is 0.5 μm or more, the occurrence of black spots is suppressed, which is preferable from the viewpoint of dot images. When the thickness is 10 μm or less, the occurrence of an increase in residual potential is suppressed, which is preferable from the viewpoint of a dot image. As for the film thickness of an intermediate | middle layer, 0.5-5 micrometers is more preferable.

Moreover, it is preferable that the said intermediate | middle layer is an insulating layer substantially. Here, the insulating layer has a volume resistance of 1 × 10 ⁸ Ω · cm or more. The volume resistance of the intermediate layer and the protective layer of the present invention is preferably 1 × 10 ⁸ to 10 ¹⁵ Ω · cm, more preferably 1 × 10 ⁹ to 10 ¹⁴ Ω · cm, still more preferably 2 × 10 ⁹ to 1 ×. 10 ¹³ Ω · cm. The volume resistance can be measured as follows.

  Measurement conditions: According to JIS: C2318-1975.

Measuring instrument: Hiresta IP manufactured by Mitsubishi Yuka
Measurement conditions: Measurement probe HRS
Applied voltage: 500V
Measurement environment: 30 ± 2 ℃, 80 ± 5RH%
When the volume resistance is 1 × 10 ⁸ Ω · cm or more, the charge blocking property of the intermediate layer is maintained, which is preferable from the viewpoint of suppressing the occurrence of black spots and the potential holding property of the organic photoreceptor, and good image quality is obtained. . On the other hand, if it is 10 ¹⁵ Ω · cm or less, it is preferable from the viewpoint of suppressing an increase in residual potential in repeated image formation, and good image quality can be obtained.

(Photosensitive layer)
The photosensitive layer configuration of the photoreceptor of the present invention may be a single layer photosensitive layer configuration in which a charge generation function and a charge transport function are provided on one layer on the intermediate layer. It is preferable that the generation layer (CGL) and the charge transport layer (CTL) be separated.

  By adopting a configuration in which the functions are separated, an increase in the residual potential due to repeated use can be controlled to be small, and other electrophotographic characteristics can be easily controlled according to the purpose. In the negatively charged photoconductor, it is preferable that a charge generation layer (CGL) is formed on the intermediate layer and a charge transport layer (CTL) is formed thereon.

  The structure of the photosensitive layer of the function-separated negatively charged photoreceptor will be described below.

(Charge generation layer)
In the organophotoreceptor of the present invention, it is preferable to use a charge generation material having high sensitivity characteristics in a wavelength region of 350 nm to 500 nm as a charge generation material (CGM). Examples of such a charge generating substance include perylene compounds such as azo pigments and perylene pigments, and polycyclic quinone compounds such as polycyclic quinone pigments. Particularly, polycyclic quinone compounds and perylene compounds are preferably used. .

  In the present invention, the polycyclic quinoline compound refers to anthanthrone, pyranthrone, violanthrone, isoviolanthrone, diphthaloylpyrene, dinaphthopyrenequinone and the like.

  The perylene-based compound refers to a perylene derivative having a perylene or bisperylene skeleton.

  In the present invention, these pigments can be used in combination. Examples of pigment compounds preferably used in the present invention are shown below.

  The charge generation layer preferably uses a binder as a dispersion medium for CGM. As the binder, known resins can be used, and the most preferred resins include formal resin, butyral resin, silicone resin, silicone-modified butyral resin, phenoxy resin and the like.

  The ratio of the binder to the charge generating material is preferably 20 to 600 parts by mass with respect to 100 parts by mass of the binder. By using these resins, the increase in residual potential associated with repeated use can be minimized. The thickness of the charge generation layer is preferably 0.3 μm to 2 μm.

(Charge transport layer)
In the present invention, the charge transport layer may be a single layer or a plurality of charge transport layers. When composed of a plurality of charge transport layers, the uppermost charge transport layer preferably contains inorganic fine particles.

  The charge transport layer contains a charge transport material (CTM) and a binder resin that disperses and forms a CTM. Other substances may contain additives such as inorganic fine particles and antioxidants as necessary.

  As the charge transport material (CTM), the compound represented by the general formula (1) according to the present invention is preferably used.

In Formula (1), _{R 1} and _{R 2} represents an alkyl group or an alkoxy group having 1 to 5 carbon atoms. R ₃ and R ₄ represent a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms or an alkoxy group. n represents an integer of 0 to 2, and o represents an integer of 0 to 3. l and m represent an integer of 0 to 5, and A, B, C, and D represent a hydrogen atom, a substituted or unsubstituted alkyl group, an alkoxy group, or an aryl group. However, A, B, C and D are not simultaneously hydrogen atoms.

Examples of the alkyl group for R ₁ and R ₂ include a methyl group, an ethyl group, a propyl group, a butyl group, and a pentyl group. Examples of the alkoxy group in R _{1 to} R ₄ include a methoxy group, an ethoxy group, a propoxy group, a butoxy group, and a pentoxy group.

Examples of the alkyl group in R ₃ and R ₄ include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, and a cyclohexyl group. Examples of the alkoxy group in R _{1 to} R ₄ include a methoxy group, an ethoxy group, a propoxy group, a butoxy group, and a pentoxy group. Examples of the substituted alkyl group for R ₃ and R ₄ include phenyl-substituted alkyl.

  Examples of the substituent for the alkyl group, alkoxy group or aryl group in A to D include an alkyl group and an alkoxy group.

  In addition, examples of the alkyl group in A to D include an alkyl group having 1 to 4 carbon atoms such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, and a t-butyl group, an alkoxyalkyl group, and benzyl. And a substituted alkyl group such as a phenethyl group. Examples of the alkoxy group include a methoxy group, an ethoxy group, and a propoxy group. A phenyl group is mentioned as an aryl group.

  Further, the compound according to the present invention has a calculated value Dihed of the dihedral angle of the biphenyl moiety (having A to D) by a structure optimization calculation using a semi-empirical molecular orbital calculation using the AM-1 parameter. It is necessary that ° ≦ Dihed ≦ 80 °.

  The dihed calculated value of the dihedral angle of the biphenyl moiety in the above general formula (1) by structure optimization calculation using semi-empirical molecular orbital calculation using the AM-1 parameter is as follows. Defined as the angle formed by the plane A containing the atom 1-2-3 and the plane B containing the atom 2-3-4 when the atom 1-2-3-4 is bonded, and the axis between the atoms 2-3 It changes by rotating.

  In the present invention, the two-plane calculated value Dihed needs to be 45 ° to 80 ° from the viewpoint of sensitivity and durability, and is particularly preferably 45 ° to 60 °.

  Specific examples of the compound represented by the general formula (1) are listed below.

  In order to synthesize the compound represented by the general formula (1), it is possible to synthesize diphenylamine and aryl halide by the Ullmann reaction using copper and alkali as a catalyst, or by the Suzuki coupling method using a palladium catalyst. Can do.

Compound Represented by General Formula (2) In the present invention, it is also a preferred embodiment when the compound represented by General Formula (1) is the compound represented by General Formula (2).

In the general formula _{(2), R 5, R} 6, R 7 and _{R 8} represents an alkyl group or an alkoxy group having 1 to 5 carbon atoms. p represents an integer of 0 to 5, q represents an integer of 0 to 4, r represents an integer of 0 to 2, and s represents an integer of 0 to 3. A, B, C and D have the same meanings as A, B, C and D in the general formula (1). However, A, B, C and D are not simultaneously hydrogen atoms.

Examples of the alkyl group and alkoxy group in R ₅ , R ₆ , R ₇ , and R ₈ include the same alkyl groups and alkoxy groups as those in R ₁ and R ₂ .

Examples of the alkyl group in R ₉ and R ₁₀ include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, and the ring structure formed by bonding R ₉ and R ₁₀ includes a cyclohexyl group, A cyclopentyl group etc. are mentioned. Moreover, a phenyl group is mentioned as an aryl group.

  Specific examples of the compound represented by the general formula (2) are listed below.

  In addition to these compounds, known hole transporting (P-type) charge transport materials (CTM) can be used, or they may be used in combination. For example, triphenylamine derivatives, hydrazone compounds, styryl compounds, benzidine compounds and the like other than the compounds represented by the general formula (1) or (2) can be used. Specific examples are given below.

  These charge transport materials are usually dissolved in a suitable binder resin to form a layer.

  The binder resin used for the charge transport layer (CTL) may be either a thermoplastic resin or a thermosetting resin. For example, polystyrene, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, polyvinyl butyral resin, epoxy resin, polyurethane resin, phenol resin, polyester resin, alkyd resin, polycarbonate resin, silicone resin, melamine resin, and these resins A copolymer resin containing two or more of the repeating unit structures. In addition to these insulating resins, high molecular organic semiconductors such as poly-N-vinylcarbazole can be used. Of these, polycarbonate resins are most preferred because of their low water absorption and good CTM dispersibility and electrophotographic characteristics.

  The ratio of the binder resin to the charge transport material is preferably 50 to 200 parts by mass with respect to 100 parts by mass of the binder resin.

  The total thickness of the charge transport layer is preferably 10 to 25 μm from the viewpoint of preventing the deterioration of dot reproducibility. Moreover, it is preferable that the film thickness of the electric charge transport layer used as a surface layer is 1.0-8.0 micrometers.

  Solvents or dispersion media used to form layers such as intermediate layers, charge generation layers, and charge transport layers include n-butylamine, diethylamine, ethylenediamine, isopropanolamine, triethanolamine, triethylenediamine, N, N-dimethylformamide, acetone , Methyl ethyl ketone, methyl isopropyl ketone, cyclohexanone, benzene, toluene, xylene, chloroform, dichloromethane, 1,2-dichloroethane, 1,2-dichloropropane, 1,1,2-trichloroethane, 1,1,1-trichloroethane, trichloroethylene, Tetrachloroethane, tetrahydrofuran, dioxolane, dioxane, methanol, ethanol, butanol, isopropanol, ethyl acetate, butyl acetate, dimethyl sulfoxide, methyl cello Lube, and the like. Although this invention is not limited to these, Solvents friendly to global environment, such as tetrahydrofuran and methyl ethyl ketone, are used preferably. These solvents may be used alone or as a mixed solvent of two or more.

  Next, as a coating processing method for producing the organic photoreceptor, a coating processing method such as dip coating or spray coating is used in addition to the slide hopper type coating device. Further, it is most preferable to use a circular slide hopper type coating apparatus for forming the surface layer.

  Among the coating liquid supply type coating apparatuses, the coating processing method using the slide hopper type coating apparatus is most suitable when the above-described dispersion using a low boiling point solvent is used as the coating liquid, and is a cylindrical photoconductor. In this case, the coating is preferably performed using a circular slide hopper type coating apparatus described in detail in JP-A No. 58-189061 and the like.

  In the coating method using a circular slide hopper type coating apparatus, the slide surface end and the base material are arranged with a certain gap (about 2 μm to 2 mm), so that the base material is not damaged, and layers having different properties are multilayered. Even in the case of forming, it can be applied without damaging the already applied layer. Furthermore, when multiple layers with different properties and dissolved in the same solvent are formed, the time in the solvent is much shorter compared to the dip coating method, so that the lower layer component hardly elutes to the upper layer side, and the coating tank Can be applied without degrading the dispersibility of the inorganic fine particles of the present invention.

  The surface layer of the photoreceptor of the present invention preferably contains an antioxidant from the viewpoint of preventing image blur. The surface layer is easily oxidized by an active gas such as NOx or ozone when the photosensitive member is charged, and image blur is likely to occur. However, the presence of an antioxidant can prevent the occurrence of image blur.

  Antioxidants typically represent the prevention or suppression of the action of oxygen on auto-oxidizing substances present in or on the surface of an organic photoreceptor under light, heat, discharge, or other conditions. It is a substance with the property to do. Typical examples include the following compound groups.

  Next, an image forming apparatus using the organic photoreceptor according to the present invention will be described.

  An image forming apparatus 1 shown in FIG. 1 is a digital image forming apparatus, and includes an image reading unit A, an image processing unit B, an image forming unit C, and a transfer paper transport unit D as a transfer paper transport unit. Yes.

  An automatic document feeder that automatically conveys the document is provided above the image reading unit A. The document placed on the document table 11 is separated and conveyed by the document conveyance roller 12 to the reading position 13a. The image is read. The document after the document reading is completed is discharged onto the document discharge tray 14 by the document transport roller 12.

  On the other hand, the image of the original when placed on the platen glass 13 is read at a speed v of the first mirror unit 15 comprising the illumination lamp and the first mirror constituting the scanning optical system, and the V-shaped first image is located. Reading is performed by moving the second mirror unit 16 composed of the two mirrors and the third mirror in the same direction at the speed v / 2.

  The read image is formed on the light receiving surface of the image sensor CCD, which is a line sensor, through the projection lens 17. The line-shaped optical image formed on the image sensor CCD is sequentially photoelectrically converted into an electric signal (luminance signal) and then A / D converted, and the image processing unit B performs processing such as density conversion and filter processing. Then, the image data is temporarily stored in the memory.

  In the image forming unit C, as an image forming unit, a drum-shaped photoconductor 21 as an image carrier, a charging means (charging step) 22 for charging the photoconductor 21 on the outer periphery thereof, and a surface potential of the charged photoconductor. Potential detecting means 220 for detecting the toner, developing means (developing process) 23, transfer / conveying belt device 45 serving as a transferring means (transfer process), cleaning device (cleaning process) 26 for the photosensitive member 21, and light discharging means (light discharging process). PCL (precharge lamps) 27 are arranged in the order of operation. Further, on the downstream side of the developing means 23, a reflection density detecting means 222 for measuring the reflection density of the patch image developed on the photosensitive member 21 is provided. The photoconductor 21 uses the organic photoconductor of the present invention and is driven to rotate in the clockwise direction shown in the figure.

  After the rotating photosensitive member 21 is uniformly charged by the charging unit 22, an image based on an image signal called from the memory of the image processing unit B by an exposure optical system as an image exposure unit (image exposure step) 30 is used. Exposure is performed. The exposure optical system as the image exposure means 30 as the writing means uses a laser diode (not shown) as a light source, and the optical path is bent by the reflection mirror 32 via the rotating polygon mirror 31, the fθ lens 34, and the cylindrical lens 35, and main scanning is performed. Therefore, image exposure is performed on the photoconductor 21 at the position Ao, and an electrostatic latent image is formed by rotation (sub-scanning) of the photoconductor 21. In one example of the present embodiment, the character portion is exposed to form an electrostatic latent image.

  The image forming apparatus of the present invention includes an exposure unit that uses a semiconductor laser or a light emitting diode having an oscillation wavelength of 350 to 500 nm as an image exposure light source when an electrostatic latent image is formed on a photoreceptor. Using these image exposure light sources, the exposure dot diameter in the writing direction is narrowed down to 10 to 50 μm, and digital exposure is performed on the organic photoreceptor, so that it is 600 dpi (dpi: the number of dots per 2.54 cm) or more. A high resolution electrophotographic image of 2500 dpi can be obtained.

The exposure dot diameter refers to the length of the exposure beam along the main scanning direction (Ld: measured at the maximum length) in a region where the intensity of the exposure beam is 1 / e ² or more of the peak intensity.

The light beams used have such a scanning optical system and LED solid scanner using a semiconductor laser, there is a Gaussian distribution and Lorentz distribution and the like also the light intensity distribution is in each 1 / e ² or more regions of peak intensity The exposure dot diameter according to the present invention is used.

  The image forming apparatus of the present invention has a developing unit that visualizes the electrostatic latent image into a toner image. The electrostatic latent image on the photoconductor 21 is reversely developed by the developing unit 23, and a visible toner image is formed on the surface of the photoconductor 21.

  In the image forming method of the present invention, it is preferable to use a polymerized toner as a developer used in the developing means. By using a polymer toner having a uniform shape and particle size distribution in combination with the organic photoreceptor according to the present invention, an electrophotographic image with better sharpness can be obtained.

  In the transfer paper transport section D, paper feed units 41 (A), 41 (B), and 41 (C) are provided below the image forming unit as transfer paper storage means for storing transfer paper P of different sizes. Further, a manual paper feeding unit 42 for manually feeding paper is provided on the side, and the transfer paper P selected from any of them is fed along the transport path 40 by the guide roller 43 and fed. The transfer paper P is temporarily stopped by a pair of paper feed registration rollers 44 that correct the inclination and bias of the transfer paper P to be transferred, and then fed again. The transport path 40, the pre-transfer roller 43a, and the paper feed path 46 The transfer paper P is guided while being guided by the entry guide plate 47 and is placed and conveyed on the transfer conveyance belt 454 of the transfer conveyance belt device 45 by the transfer electrode 24 and the separation electrode 25 at the transfer position Bo. Transcribed, transfer sheet P is separated from the photosensitive member 21 surface, it is conveyed to the fixing unit 50 by the transfer conveyor belt device 45.

  The fixing unit 50 includes a fixing roller 51 and a pressure roller 52. By passing the transfer paper P between the fixing roller 51 and the pressure roller 52, the toner is fixed by heating and pressing. After the toner image has been fixed, the transfer paper P is discharged onto the paper discharge tray 64.

  The above describes the state in which image formation is performed on one side of the transfer paper. However, in the case of double-sided copying, the paper discharge switching member 170 is switched, the transfer paper guide 177 is opened, and the transfer paper P is indicated by a broken arrow. Conveyed in the direction.

  Further, the transfer paper P is transported downward by the transport mechanism 178 and switched back by the transfer paper reversing unit 179, and the rear end portion of the transfer paper P becomes the leading end portion and transported into the duplex copying paper supply unit 130. The

  The transfer paper P is moved in a paper feed direction by a conveyance guide 131 provided in the double-sided copy paper supply unit 130, the transfer paper P is re-fed by the paper supply roller 132, and the transfer paper P is guided to the conveyance path 40. .

  Again, as described above, the transfer paper P is conveyed in the direction of the photosensitive member 21, the toner image is transferred to the back surface of the transfer paper P, fixed by the fixing unit 50, and then discharged onto the paper discharge tray 64.

  The image forming apparatus of the present invention is configured by integrally combining the above-described photosensitive member and components such as a developing device and a cleaning device as a process cartridge, and this unit is configured to be detachable from the apparatus main body. Also good. Further, at least one of a charging device, an image exposure device, a developing device, a transfer or separation device, and a cleaning device is integrally supported together with a photosensitive member to form a process cartridge, and a single unit that is detachable from the apparatus main body. It is good also as a structure which can be attached or detached using guide means, such as a rail of an apparatus main body.

  FIG. 2 is a cross-sectional configuration diagram of a color image forming apparatus showing an embodiment of the present invention.

  This color image forming apparatus is called a tandem type color image forming apparatus, and includes four sets of image forming units (image forming units) 10Y, 10M, 10C, and 10Bk, an endless belt-shaped intermediate transfer body unit 7, and a feeding unit. The paper transport unit 21 and the fixing unit 24 are included. A document image reading device SC is disposed above the main body A of the image forming apparatus.

  The image forming unit 10Y that forms a yellow image includes a charging unit (charging step) 2Y, an exposure unit (exposure step) 3Y, and a developing unit disposed around a drum-shaped photoconductor 1Y as a first image carrier. A unit (developing step) 4Y, a primary transfer roller 5Y as a primary transfer unit (primary transfer step), and a cleaning unit 6Y. An image forming unit 10M that forms a magenta image includes a drum-shaped photosensitive member 1M as a first image carrier, a charging unit 2M, an exposure unit 3M, a developing unit 4M, a primary transfer roller 5M as a primary transfer unit, It has a cleaning means 6M. An image forming unit 10C for forming a cyan image includes a drum-shaped photoreceptor 1C as a first image carrier, a charging unit 2C, an exposure unit 3C, a developing unit 4C, and a primary transfer roller 5C as a primary transfer unit. It has cleaning means 6C. The image forming unit 10Bk that forms a black image includes a drum-shaped photoreceptor 1Bk as a first image carrier, a charging unit 2Bk, an exposure unit 3Bk, a developing unit 4Bk, a primary transfer roller 5Bk as a primary transfer unit, and a cleaning unit. 6Bk.

  The four sets of image forming units 10Y, 10M, 10C, and 10Bk include charging means 2Y, 2M, 2C, and 2Bk that rotate around the photosensitive drums 1Y, 1M, 1C, and 1Bk, and image exposure means 3Y, 3M, 3C, 3Bk, rotating developing means 4Y, 4M, 4C, and 4Bk, and cleaning means 5Y, 5M, 5C, and 5Bk for cleaning the photosensitive drums 1Y, 1M, 1C, and 1Bk.

  The image forming units 10Y, 10M, 10C, and 10Bk have the same configuration except that the colors of toner images formed on the photoreceptors 1Y, 1M, 1C, and 1Bk are different, and the image forming unit 10Y is taken as an example in detail. explain.

  The image forming unit 10Y has a charging unit 2Y (hereinafter simply referred to as a charging unit 2Y or a charger 2Y), an exposure unit 3Y, a developing unit 4Y, and a cleaning unit 5Y (around a photosensitive drum 1Y as an image forming body). Hereinafter, the cleaning means 5Y or the cleaning blade 5Y) is simply disposed, and a yellow (Y) toner image is formed on the photosensitive drum 1Y. In the present embodiment, in the image forming unit 10Y, at least the photosensitive drum 1Y, the charging unit 2Y, the developing unit 4Y, and the cleaning unit 5Y are provided so as to be integrated.

  The charging unit 2Y is a unit that applies a uniform potential to the photosensitive drum 1Y. In the present embodiment, a corona discharge type charger 2Y is used for the photosensitive drum 1Y.

  The image exposure unit 3Y performs exposure based on the image signal (yellow) on the photosensitive drum 1Y given a uniform potential by the charger 2Y to form an electrostatic latent image corresponding to the yellow image. As the exposure means 3Y, the exposure means 3Y includes an LED in which light emitting elements are arranged in an array in the axial direction of the photosensitive drum 1Y and an imaging element (trade name; Selfoc lens), or A laser optical system or the like is used.

  The image forming apparatus of the present invention is configured by integrally combining the above-described photosensitive member and components such as a developing device and a cleaning device as a process cartridge (image forming unit), and this image forming unit is connected to the apparatus main body. It may be configured to be detachable. Further, at least one of a charger, an image exposure device, a developing device, a transfer or separation device, and a cleaning device is integrally supported together with a photosensitive member to form a process cartridge (image forming unit), which is detachable from the apparatus main body. A single image forming unit may be detachable using guide means such as a rail of the apparatus main body.

  The endless belt-like intermediate transfer body unit 7 includes an endless belt-like intermediate transfer body 70 as a second image carrier having a semiconductive endless belt shape that is wound around a plurality of rollers and is rotatably supported.

  Each color image formed by the image forming units 10Y, 10M, 10C, and 10Bk is sequentially transferred onto a rotating endless belt-shaped intermediate transfer body 70 by primary transfer rollers 5Y, 5M, 5C, and 5Bk as primary transfer means. Thus, a synthesized color image is formed. A transfer material P as a transfer material (a support for carrying a fixed final image: for example, plain paper, a transparent sheet, etc.) housed in the paper feed cassette 20 is fed by a paper feed means 21 and a plurality of intermediates. After passing through rollers 22A, 22B, 22C, 22D and registration roller 23, they are conveyed to a secondary transfer roller 5b as a secondary transfer means, and are secondarily transferred onto a transfer material P to transfer a color image all at once. The transfer material P onto which the color image has been transferred is subjected to fixing processing by the fixing unit 24, is sandwiched between paper discharge rollers 25, and is placed on a paper discharge tray 26 outside the apparatus. Here, a transfer support for a toner image formed on a photosensitive member such as an intermediate transfer member or a transfer material is collectively referred to as a transfer medium.

  On the other hand, after the color image is transferred to the transfer material P by the secondary transfer roller 5b as the secondary transfer means, the residual toner is removed by the cleaning means 6b from the endless belt-shaped intermediate transfer body 70 in which the transfer material P is separated by curvature. The

  During the image forming process, the primary transfer roller 5Bk is always in contact with the photoreceptor 1Bk. The other primary transfer rollers 5Y, 5M, and 5C are in contact with the corresponding photoreceptors 1Y, 1M, and 1C, respectively, only during color image formation.

  The secondary transfer roller 5b contacts the endless belt-shaped intermediate transfer body 70 only when the transfer material P passes through the secondary transfer roller 5b.

  Further, the housing 8 can be pulled out from the apparatus main body A through the support rails 82L and 82R.

  The housing 8 includes image forming units 10Y, 10M, 10C, and 10Bk and an endless belt-shaped intermediate transfer body unit 7.

  The image forming units 10Y, 10M, 10C, and 10Bk are arranged in tandem in the vertical direction. An endless belt-shaped intermediate transfer body unit 7 is disposed on the left side of the photoreceptors 1Y, 1M, 1C, and 1Bk in the drawing. The endless belt-shaped intermediate transfer body unit 7 includes an endless belt-shaped intermediate transfer body 70 that can be rotated by winding rollers 71, 72, 73, 74, primary transfer rollers 5Y, 5M, 5C, 5Bk, and a cleaning unit 6b. Consists of.

  Next, FIG. 3 shows a color image forming apparatus using the organic photoreceptor of the present invention (a copying machine having at least a charging means, an exposing means, a plurality of developing means, a transfer means, a cleaning means and an intermediate transfer body around the organic photoreceptor. 1 is a cross-sectional view of a configuration of a laser beam printer). The belt-shaped intermediate transfer body 70 uses an elastic body having a medium resistance.

  Reference numeral 1 denotes a rotary drum type photoconductor that is repeatedly used as an image forming body, and is rotationally driven in a counterclockwise direction indicated by an arrow at a predetermined peripheral speed.

  In the rotation process, the photoreceptor 1 is uniformly charged to a predetermined polarity and potential by a charging means (charging process) 2, and then time-series electric digital of image information by an image exposure means (image exposure process) 3 (not shown). An electrostatic latent image corresponding to the yellow (Y) color component image (color information) of the target color image is formed by receiving image exposure by scanning exposure light or the like by a laser beam modulated in accordance with the pixel signal. The

  Then, the electrostatic latent image is developed with yellow toner as the first color by yellow (Y) developing means: developing step (yellow color developing device) 4Y. At this time, the second to fourth developing means (magenta developer, cyan developer, black developer) 4M, 4C, and 4Bk are turned off and do not act on the photosensitive member 1. The yellow toner image of the first color is not affected by the second to fourth developing devices.

  The intermediate transfer member 70 is stretched by rollers 79a, 79b, 79c, 79d, and 79e, and is driven to rotate in the clockwise direction at the same peripheral speed as the photosensitive member 1.

  The yellow toner image of the first color formed and supported on the photosensitive member 1 is applied to the intermediate transfer member 70 from the primary transfer roller 5a in the process of passing through the nip portion between the photosensitive member 1 and the intermediate transfer member 70. The intermediate transfer (primary transfer) is sequentially performed on the outer peripheral surface of the intermediate transfer body 70 by the electric field formed by the primary transfer bias.

  The surface of the photoreceptor 1 after the transfer of the first color yellow toner image corresponding to the intermediate transfer body 70 is cleaned by the cleaning device 6a.

  Similarly, the second color magenta toner image, the third color cyan toner image, and the fourth color black (black) toner image are sequentially superimposed and transferred onto the intermediate transfer body 70 to correspond to the target color image. A superimposed color toner image is formed.

  The secondary transfer roller 5b is supported in parallel with the secondary transfer counter roller 79b so as to be separated from the lower surface of the intermediate transfer body 70.

  The primary transfer bias for sequentially superimposing and transferring the first to fourth color toner images from the photosensitive member 1 to the intermediate transfer member 70 has a polarity opposite to that of the toner and is applied from a bias power source. The applied voltage is, for example, in the range of +100 V to +2 kV.

  In the primary transfer process of the first to third color toner images from the photoreceptor 1 to the intermediate transfer member 70, the secondary transfer roller 5b and the intermediate transfer member cleaning means 6b can be separated from the intermediate transfer member 70. is there.

  When the superimposed color toner image transferred onto the belt-shaped intermediate transfer member 70 is transferred to the transfer material P, which is the second image carrier, the secondary transfer roller 5b is brought into contact with the belt of the intermediate transfer member 70. At the same time, the transfer material P is fed from the pair of paper registration rollers 23 through the transfer paper guide to the belt of the intermediate transfer body 70 to the contact nip with the secondary transfer roller 5b at a predetermined timing. A secondary transfer bias is applied to the secondary transfer roller 5b from a bias power source. By this secondary transfer bias, the superimposed color toner image is transferred (secondary transfer) from the intermediate transfer body 70 to the transfer material P as the second image carrier. The transfer material P that has received the transfer of the toner image is introduced into the fixing means 24 and fixed by heating.

  The image forming apparatus of the present invention is generally applicable to electrophotographic apparatuses such as electrophotographic copying machines, laser printers, LED printers, and liquid crystal shutter printers, and further displays, recordings, light printing, plate making and facsimiles using electrophotographic technology. The present invention can be widely applied to such devices.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these. Unless otherwise specified, “parts” in the examples represents “parts by mass”.

Example 1
Production of Photoreceptor 1 Photoreceptor 1 was produced as follows.

Intermediate layer On the washed cylindrical aluminum substrate (10 points surface roughness Rz: processed to 0.81 μm by cutting), the following intermediate layer coating solution was applied by dip coating, and dried at 120 ° C. for 30 minutes. An intermediate layer having a dry film thickness of 5 μm was formed.

(Preparation of intermediate layer coating solution)
The following intermediate layer dispersion was diluted twice with the same mixed solvent, and allowed to stand overnight, then filtered (filter; rigesh mesh filter manufactured by Nihon Pall Corporation, nominal filtration accuracy: 5 microns, pressure: 50 kPa), and the intermediate layer coating solution was Prepared.

(Preparation of intermediate layer dispersion)
Binder resin: (Exemplary polyamide N-1) 1 part Rutile titanium oxide (primary particle size 35 nm; pre-immersed in a dye solution (solvent: ethanol) described in Table 1 for 12 hours and dye adsorption treatment) 5.6 parts Ethanol / n-propyl alcohol / THF (= 45/20/30 mass ratio) 10 parts The above components are mixed and dispersed in a batch system for 10 hours using a sand mill disperser to disperse the intermediate layer. A liquid was prepared. This coating solution was applied by a dip coating method to form an intermediate layer having a thickness of 3 μm.

Charge generation layer: CGL
Charge generating material (CGM): Exemplified compound CGM1-6 24 parts Polyvinyl butyral resin “ESREC BL-1” (manufactured by Sekisui Chemical Co., Ltd.) 12 parts 2-butanone / cyclohexanone = 4/1 (v / v) 300 parts Were mixed and dispersed using a sand mill to prepare a charge generation layer coating solution. This coating solution was applied onto the intermediate layer by a dip coating method to form a charge generation layer having a dry film thickness of 0.5 μm on the intermediate layer.

Charge transport layer (CTL)
Charge transport material (CTM) (described in Table 1) 225 parts Polycarbonate (Z300: manufactured by Mitsubishi Gas Chemical Company) 300 parts Antioxidant (Exemplary Compound AO1-1) 3 parts Tetrahydrofuran 1600 parts Toluene 400 parts Silicon oil (KF-96) : Manufactured by Shin-Etsu Chemical Co., Ltd.) 1 part was mixed and dissolved to prepare a charge transport layer coating solution 1. This coating solution was applied onto the charge generation layer by a dip coating method and dried at 120 ° C. for 70 minutes to form a charge transport layer having a dry film thickness of 20.0 μm.

Production of photoconductors 2 to 20 Photoconductors 2 to 20 were produced in the same manner as photoconductor 1 except that the charge transport material, the dye, and the metal oxide particles were changed as shown in Table 1 in the production of photoconductor 1. .

Production of Photoreceptors 21 and 23 Photoreceptors 21 and 23 were produced in the same manner as in the production of the photoreceptors 19 and 3 except that the film thickness of the intermediate layer was changed to 6 μm.

Production of Photoreceptor 22 Photoreceptor 22 was produced in the same manner as in the production of Photoreceptor 3, except that the thickness of the intermediate layer was changed to 1.5 μm.

<< Evaluation of photoconductor >>
The manufactured photoreceptor was repeatedly evaluated for potential stability and image characteristics (interference fringe (moire) resistance, black spot resistance, transfer memory resistance) as follows.

(Repetitive potential stability)
Basically, the digital copying machine bizhub 920 (manufactured by Konica Minolta Business Technologies, Inc.) having the configuration shown in FIG. 1 (using a 405 nm semiconductor laser as an image exposure light source, beam diameter of 30 μm, 1200 dpi (dpi is about 2.54) The initial dark portion potential (Vo) and the initial bright portion were modified using the surface potential meter and the surface potential of the photoconductor surface. The potential (Vi) was set to around −700 V and −200 V, respectively, charging and exposure were repeated 10,000 times, and the fluctuation amounts (ΔVo, ΔVi) of Vo and Vi were measured and used as repeated potential stability indicators. Note that minus represents a decrease in potential, and plus represents an increase in potential.

(Image characteristics)
Using a modified machine (using a 405 nm semiconductor laser) used for repeated potential stability evaluation, the photoconductors 1 to 20 were mounted on the copying machine, and image evaluation was performed for the following items.
(1) Interference fringe (moire) resistance A halftone image of the entire surface of A3 was formed, and interference fringe (moire) resistance was evaluated according to the following criteria.

A: No occurrence (good)
○: Slight interference fringe generation (no problem in practical use)
×: Interference fringe generation (practical problem)
(2) Black spot resistance A white-colored image of the entire surface of A3 was collected in a high-temperature and high-humidity environment (30 ° C, 85% RH), and the number of black spots generated for each drum diameter cycle of the photoconductor was counted. In general, black pot resistance was evaluated.

A: Good (no occurrence)
○: Slight black spots (no problem in practical use)
×: Black spot generated (practical problem)
(3) Transfer memory tolerance Using the A3 test chart with a 5cm square black solid image printed on the tip of a white solid image, the transfer memory resistance is evaluated according to the following criteria in a low temperature and low humidity environment (10 ° C, 15% RH). did.

A: Good (no occurrence)
○: Generation of slight transfer memory (no problem in practical use)
×: Generation of transfer memory (problematic problems)
The results are shown in Table 1.

  As is clear from Table 1, the photoreceptors 1 to 18 of the present invention are excellent in repeated potential stability, black spot resistance, and transfer memory resistance to 350 to 500 nm irradiation light such as short wavelength laser light. In particular, even in image evaluation using a short-wavelength laser beam of 405 nm, it can be seen that it is superior in resistance to interference fringes and superior in image reproduction stability as compared with the photoconductors 19 and 20 as comparative examples.

  It can also be seen that the effect of the present invention cannot be obtained only by increasing the amount of metal oxide particles used (photosensitive member 21 (comparative example)).

10Y, 10M, 10C, 10Bk Image forming unit 1Y, 1M, 1C, 1Bk Photoconductor 2Y, 2M, 2C, 2Bk Charging unit 3Y, 3M, 3C, 3Bk Exposure unit 4Y, 4M, 4C, 4Bk Developing unit

Claims (8)

In an electrophotographic photoreceptor having an intermediate layer containing metal oxide particles and a photosensitive layer sequentially laminated on a conductive support, the metal oxide particles are dyes having an absorption maximum in a wavelength region of 350 to 500 nm. An electrophotographic photosensitive member characterized by being coated. The electrophotographic photosensitive member according to claim 1, wherein the metal oxide particles are titanium oxide. The electrophotographic photosensitive member according to claim 1, wherein the dye has an acidic group in the molecule. The electrophotographic photoreceptor according to claim 1, wherein the photosensitive layer contains a compound represented by the following general formula (1) or (2).

[Wherein, R ₁ and R ₂ each independently represents an alkyl group or an alkoxy group having 1 to 5 carbon atoms. R ₃ and R ₄ each independently represents a substituted or unsubstituted alkyl group or alkoxy group having 1 to 5 carbon atoms. n represents an integer of 0 to 2, and o represents an integer of 0 to 3. l and m each independently represents an integer of 0 to 5. A, B, C and D each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, an alkoxy group or an aryl group. However, A, B, C and D are not simultaneously hydrogen atoms. ]

[Wherein, R ₅ , R ₆ , R ₇ , and R ₈ each independently represents an alkyl group or an alkoxy group having 1 to 5 carbon atoms. p represents an integer of 0 to 5, q represents an integer of 0 to 4, r represents an integer of 0 to 2, and s represents an integer of 0 to 3. R ₉ and R ₁₀ each independently represents an alkyl group or an aryl group, and R ₉ and R ₁₀ may combine to form a ring structure. A, B, C and D have the same meanings as A, B, C and D in the general formula (1). However, A, B, C and D are not simultaneously hydrogen atoms. ] The electrophotographic photosensitive member according to claim 1, wherein the electrophotographic photosensitive member has a surface protective layer on the photosensitive layer. A charging step for applying a uniform charging potential on the electrophotographic photosensitive member, and exposing the electrostatic latent image on the electrophotographic photosensitive member having the charging potential with light having a wavelength in the range of 350 to 500 nm. 6. An image forming method comprising: an exposing step of forming; a developing step of developing the electrostatic latent image into a toner image; and a step of transferring the toner image to a transfer medium. An image forming method using the electrophotographic photosensitive member according to any one of the above items. An image forming apparatus using the image forming method according to claim 6. A process cartridge used in the image forming apparatus according to claim 7 includes at least one of the electrophotographic photosensitive member according to any one of claims 1 to 5 and a charging unit, an image exposing unit, and a developing unit. A process cartridge which is integrally formed and configured to be able to be inserted into and removed from the image forming apparatus.

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