JP2007108314A - Organic photoreceptor, image forming method and apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic photoreceptor which can form high resolution electrophotographic images by forming high resolution electrostatic latent images by using an image exposing light source of a semiconductor laser or a light emitting diode of the 350-500 nm oscillation wavelength on an organic photoreceptor and correctly reproducing them in high resolution toner images and is suitable for printing, and also provide an image forming method and apparatus. <P>SOLUTION: The organic photoreceptor used in an image forming method, having a light exposing step to form latent electrophotographic images on an organic photoreceptor by using a semiconductor laser or a light emitting diode of the 350-500 nm oscillation wavelength, has a photosensitive layer on a conductive support, and this photosensitive layer contains a electron carrier material satisfying the general formula (1). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an organic photoconductor used for electrophotographic image formation, an image forming method, and an image forming apparatus, and more specifically, an organic photoconductor used for electrophotographic image formation used in the field of copying machines and printers, The present invention relates to an image forming method and an image forming apparatus.

  In recent years, there are increasing opportunities to use electrophotographic copying machines and printers in the fields of printing and color printing. 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 Document 1). 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.

  The cause is that the photosensitive characteristics of the electrophotographic photosensitive member and the charging characteristics of the toner of the developer do not have sufficient characteristics necessary for forming a fine dot latent image or forming a toner image.

  That is, as an electrophotographic photoreceptor, an organic photoreceptor developed for a conventional long wavelength laser (hereinafter, simply referred to as a photoreceptor) has poor sensitivity characteristics, and the exposure dot diameter is reduced using a short wavelength laser beam. When the narrowed image exposure is performed, the dot latent image is not clearly formed, and the reproducibility of the dot image tends to deteriorate. This is caused not only by the charge generation layer but also by the charge transport layer. It is necessary to identify and remove the deterioration factors of the materials and additives of each layer with respect to the short wavelength laser.

  As a deterioration factor in the charge transport layer, a charge transport material developed for a conventional organic photoreceptor easily absorbs light having a short wavelength of 300 to 500 nm, and as a result, an electrophotography such as a decrease in sensitivity and an increase in residual potential. It is easy to promote deterioration of characteristics. Furthermore, in the case of short wavelength laser exposure, fine scratches on the surface of the photosensitive layer tend to deteriorate the halftone image. Therefore, a charge transport material that does not deteriorate the elasticity of the surface of the photosensitive layer is used for the charge transport layer forming the surface of the photosensitive layer. It is necessary to develop.

  Conventionally, it has been reported that a high quality image can be obtained by combining a benzidine compound with a short wavelength laser (Patent Document 2). However, these benzidine compounds have poor solvent solubility and are likely to precipitate in the charge transport layer. As a result, streak-like scratches due to cracks are likely to occur in the charge transport layer on the surface layer, and uneven sensitivity due to deposition (sensitivity unevenness due to the location of the same photoreceptor) also occurs, degrading the halftone image. The problem is that it is easy to do.

On the other hand, in order to achieve a long life of the organic photoreceptor, there is a technique for improving the wear resistance of the photoreceptor by adding inorganic fine particles and fluorine-based fine resin particles together with a charge transport material to the charge transport layer of the surface layer. Known (Patent Document 3). However, these fine particles easily deteriorate in dispersibility when a charge transport material is contained in the surface layer, and aggregate particles of inorganic fine particles and fluorine fine particles are generated in the surface layer, causing short-wavelength laser scattering and interference unevenness. There is a problem that a high-definition dot image cannot be obtained by utilizing the wavelength laser.
JP 2000-250239 A JP 2000-147874 A JP 2004-38039 A

  The present invention has been made to solve the above problems. An object of the present invention is to form a high-density electrostatic latent image on an organic photoreceptor using image exposure of a semiconductor laser or a light emitting diode having an oscillation wavelength of 350 to 500 nm, and the characteristics of sensitivity and residual potential, or dots An organic photoreceptor having improved reproducibility, halftone image degradation, and the like, and an image forming method and an image forming apparatus using the organic photoreceptor. Another object of the present invention is to form a high-density electrostatic latent image on an organic photoreceptor using image exposure of a semiconductor laser or a light-emitting diode having an oscillation wavelength of 350 to 500 nm, and sensitivity or residual potential characteristics, or An organic photoreceptor capable of forming a high-quality color image with improved dot reproducibility, halftone image degradation, and the like, and an image forming method and an image forming apparatus using the organic photoreceptor are provided. That is.

  As a result of repeated studies on the above problems, the object of the present invention is to form a high-density electrostatic latent image on an organic photoreceptor using image exposure of a semiconductor laser or light emitting diode having an oscillation wavelength of 350 to 500 nm. In order to form an electrophotographic image with improved sensitivity, residual potential characteristics, dot reproducibility, halftone image degradation, etc., the absorption is relatively small and relatively low with respect to short-wavelength laser light, etc. The inventors have found that it is effective to use a compound having a large molecular weight and a good compatibility with a binder such as polycarbonate as a charge transport material for an organic photoreceptor, and thus completed the present invention. That is, for the above-mentioned problems that are likely to occur with exposure light of a short wavelength laser beam, an organic photoreceptor using a specific biphenyl compound as described below as a charge transport material is found to be effective. Was completed.

  That is, the present invention is achieved by using an organic photoreceptor having the following configuration.

  1. In an organic photoconductor used in an image forming method having an exposure step of forming an electrostatic latent image using a semiconductor laser having an oscillation wavelength of 350 to 500 nm or a light source of a light emitting diode on the organic photoconductor, And a photosensitive layer, and the photosensitive layer contains a charge transport material represented by the following general formula (1).

[In General Formula (1), Ar ₁ and Ar ₂ each represents an alkyl group, an aralkyl group, an aryl group, a biphenyl group, or a heterocyclic group, which may have a substituent, and R ₁ , R ₂ , R ₃ and R ₄ each represent a hydrogen atom, an alkyl group, an alkoxy group or a halogen atom; X represents —O—, —S— or — (R ₅ ) C (R ₆ ) —, (R ₅ and R ₆ each represent Represents a hydrogen atom, an alkyl group or an aryl group optionally having substituent (s)]
2. 2. The organophotoreceptor according to 1 above, wherein the photosensitive layer has a charge generation layer containing a charge generation material and a charge transport layer containing a charge transport material.

  3. 3. The organophotoreceptor according to 1 or 2 above, wherein the charge transport material of the general formula (1) has a molecular weight of 500 to 1500.

  4). 4. The organophotoreceptor according to any one of items 1 to 3, wherein the charge transport layer contains inorganic fine particles having a number average primary particle size (Dp) of 3 to 100 nm.

  5. Any one of the above 2 to 4, wherein the charge transport layer is composed of a plurality of charge transport layers, and the uppermost charge transport layer contains the charge transport material of the general formula (1) and inorganic fine particles. 2. The organophotoreceptor according to item 1.

  6). 6. The organophotoreceptor according to any one of 2 to 5, wherein the charge generation material is a polycyclic quinone compound.

  7). 6. The organophotoreceptor according to any one of items 2 to 5, wherein the charge generation material is a perylene compound.

  8). 8. The organophotoreceptor according to any one of items 2 to 7, further comprising an intermediate layer containing N-type semiconductive particles between the conductive support and the charge generation layer.

  9. 9. The organophotoreceptor according to 8 above, wherein the N-type semiconductive particles are titanium oxide.

  10. 10. The organic photoreceptor as described in 9 above, wherein the titanium oxide is a rutile titanium oxide pigment or an anatase titanium oxide pigment.

  11. 11. The organophotoreceptor according to any one of 8 to 10, wherein the intermediate layer contains a polyamide resin binder.

  12 12. The organic photoreceptor as described in 11 above, wherein the polyamide resin is a polyamide resin having a heat of fusion of 0 to 40 J / g and a water absorption of 5% by mass or less.

  13. Development that has an exposure step of forming an electrostatic latent image on an organic photoreceptor using a semiconductor laser having an oscillation wavelength of 350 to 500 nm or a light source of a light emitting diode, and developing the electrostatic latent image into a toner image In the image forming method comprising the steps, the organic photoreceptor has a photosensitive layer on a conductive support, and the photosensitive layer contains a charge transport material represented by the following general formula (1): .

[In General Formula (1), Ar ₁ and Ar ₂ each represents an alkyl group, an aralkyl group, an aryl group, a biphenyl group, or a heterocyclic group, which may have a substituent, and R ₁ , R ₂ , R ₃ and R ₄ each represent a hydrogen atom, an alkyl group, an alkoxy group or a halogen atom; X represents —O—, —S— or — (R ₅ ) C (R ₆ ) —, (R ₅ and R ₆ each represent Represents a hydrogen atom, an alkyl group or an aryl group optionally having substituent (s)]
14 Development having an exposure means for forming an electrostatic latent image on an organic photoreceptor using a semiconductor laser having an oscillation wavelength of 350 to 500 nm or a writing light source of a light emitting diode, and developing the electrostatic latent image into a toner image In the image forming apparatus having the above-mentioned means, the organic photoreceptor has a photosensitive layer on a conductive support, and the photosensitive layer contains a charge transport material of the following general formula (1). .

[In General Formula (1), Ar ₁ and Ar ₂ each represents an alkyl group, an aralkyl group, an aryl group, a biphenyl group, or a heterocyclic group, which may have a substituent, and R ₁ , R ₂ , R ₃ and R ₄ each represent a hydrogen atom, an alkyl group, an alkoxy group or a halogen atom; X represents —O—, —S— or — (R ₅ ) C (R ₆ ) —, (R ₅ and R ₆ each represent Represents a hydrogen atom, an alkyl group or an aryl group optionally having substituent (s)]

  By using the organic photoreceptor, the image forming method and the image forming apparatus of the present invention, it is possible to form a high-definition dot image, the dot reproducibility is improved, and the streak density unevenness of the halftone image can be improved. A high-quality electrophotographic image can be formed. Also in the production of a color image, a color image having good dot reproducibility and excellent color reproducibility can be produced.

  Hereinafter, the present invention will be described in detail.

  The organophotoreceptor of the present invention is an organophotoreceptor used in an image forming method having an exposure step of forming an electrostatic latent image on a photoconductive source of a semiconductor laser or a light emitting diode having an oscillation wavelength of 350 to 500 nm on the organophotoreceptor. A photosensitive layer on a conductive support, and the photosensitive layer contains the charge transport material represented by the general formula (1).

  Hereinafter, the structure of the organic photoreceptor of the present invention will be described.

  The organophotoreceptor according to the present invention contains the charge transport material of the general formula (1).

  The charge transport material represented by the general formula (1) has a large potential attenuation value with respect to a unit exposure amount with respect to an exposure light source having a wavelength of 350 to 500 nm, can form a small dot latent image sharply, and reproduce dots. Therefore, it is possible to form an electrophotographic image with improved properties and improved deterioration of the halftone image.

Among the charge transport materials of the general formula (1) according to the present invention, as a particularly preferable compound structure, Ar ₁ and Ar _{2 in the} general formula (1) are preferably aryl groups (including biphenyl groups). R ₁ , R ₂ , R ₃ and R ₄ are each preferably a hydrogen atom or an alkyl group, and X is preferably CH _{2 or} O.

  Specific examples of the compound of the general formula (1) are exemplified below.

  A method for synthesizing these compounds is described in JP-A-5-32596.

  The molecular weight of the charge transport material of the general formula (1) is preferably a charge transport material in the range of 500-1500. If the molecular weight is less than 500, it acts as a plasticizer for the binder of the charge transport layer, and the elasticity of the charge transport layer is lowered, and the surface layer is easily damaged. Further, since the physical properties of the film are deteriorated due to a decrease in the elastic modulus, the content of the charge transport material in the charge transport layer is limited. As a result, the sensitivity is lowered and the image density is likely to be lowered. On the other hand, if the molecular weight is larger than 1500, the solvent solubility is lowered and precipitates, and the image density is lowered and the dot reproducibility is liable to occur. In particular, a molecular weight of 500 to 800 is preferable.

  The organophotoreceptor according to the present invention is an organophotoreceptor containing the charge transport material of the general formula (1). The constitution of the organophotoreceptor containing these charge transport materials will be described below.

  In the present invention, the organic photoconductor means an electrophotographic photoconductor constituted by providing an organic compound with at least one of a charge generation function and a charge transport function essential to 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 it contains the charge transport material of the general formula (1), and examples thereof include the following constitutions;
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 charge generation layer, a first charge transport layer and a second charge transport layer are formed as a photosensitive layer on a conductive support. Sequentially stacked configuration;
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 5) above.

  The photoconductor may have any of the above configurations. The surface layer of the photoreceptor is a layer in contact with the air interface. When only a single-layer photosensitive layer is formed on the conductive support, the photosensitive layer is the surface layer, and the conductive layer In the case where a single-layered or laminated photosensitive layer and a surface protective layer are laminated on the conductive support, the surface protective layer is the outermost surface layer. In the present invention, the configuration 2) is most preferably used. Note that, regardless of the configuration of the photoreceptor of the present invention, an undercoat layer (intermediate layer) may be formed on the conductive support prior to the formation of the photosensitive layer.

  The charge transport layer means a layer having a function of transporting charge carriers generated in the charge generation layer by photoexposure to the surface of the organic photoreceptor, and the specific detection of the charge transport function is carried out between the charge generation layer and the charge transport layer. It can be confirmed by laminating a transport layer on a conductive support and detecting optical conductivity.

  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 photoreceptor may be either a sheet or a cylinder, but a cylindrical conductive support is preferred 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 range of straightness and shake 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 of 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.

Intermediate layer In the present invention, an intermediate layer is preferably provided between the conductive support and the photosensitive layer.

  The intermediate layer used in the present invention preferably contains N-type semiconductor particles. The N-type semiconductive particle means a particle whose main charge carrier is an electron. That is, since the main charge carriers are electrons, the intermediate layer containing the N-type semiconductive particles in the insulating binder effectively blocks hole injection from the substrate, and the electrons from the photosensitive layer. In contrast, it has a property of low blocking.

As the N-type semiconductor particles, titanium oxide (TiO ₂ ) and zinc oxide (ZnO) are preferable, and titanium oxide is particularly preferably used.

  As the N-type semiconductor particles, fine particles having a number average primary particle size in the range of 3.0 to 200 nm are used. Particularly, 5 nm to 100 nm is preferable. The number average primary particle diameter is a measured value as an average diameter in the ferret direction by observing 100 particles as primary particles at random by magnifying the fine particles 10,000 times by transmission electron microscope observation and image analysis. N-type semiconducting particles having a number average primary particle size of less than 3.0 nm are difficult to uniformly disperse in the intermediate layer binder, and easily form aggregated particles. Is likely to occur. On the other hand, N-type semiconducting particles having a number average primary particle size larger than 200 nm tend to make large irregularities on the surface of the intermediate layer, and the dot image tends to deteriorate through these large irregularities. In addition, the N-type semiconductive particles having a number average primary particle size larger than 200 nm are likely to precipitate in the dispersion and easily generate aggregates. As a result, the dot image tends to deteriorate.

  The titanium oxide particles have anatase, rutile, brookite, and amorphous forms as crystal forms. Among them, the rutile form titanium oxide pigment or the anatase form titanium oxide pigment has a rectifying property of charge passing through the intermediate layer. In other words, the mobility of electrons is increased, the charging potential is stabilized, the residual potential is prevented from increasing, and the dot image is prevented from deteriorating, which is most preferable as the N-type semiconductor particles of the present invention. .

  N-type semiconductive particles are preferably surface-treated with a polymer containing methylhydrogensiloxane units. The molecular weight of the polymer containing the methyl hydrogen siloxane unit is 1000 to 20000, and the surface treatment effect is high. As a result, the rectifying property of the N-type semiconductor particles is improved, and the N-type semiconductor particles are contained. By using the intermediate layer, the occurrence of black spots is prevented and there is an effect on the reproducibility of good dot images.

The polymer containing a methylhydrogensiloxane unit is preferably a copolymer of a structural unit of-(HSi (CH ₃ ) O)-and a structural unit other than this (other siloxane unit). As other siloxane units, dimethylsiloxane units, methylethylsiloxane units, methylphenylsiloxane units, diethylsiloxane units, and the like are preferable, and dimethylsiloxane is particularly preferable. The proportion of methylhydrogensiloxane units in the copolymer is 10 to 99 mol%, preferably 20 to 90 mol%.

  The methylhydrogensiloxane copolymer may be any of a random copolymer, a block copolymer, a graft copolymer, etc., but a random copolymer and a block copolymer are preferred. In addition to methylhydrogensiloxane, the copolymerization component may be one component or two or more components.

  The intermediate layer coating solution prepared for forming the intermediate layer used in the present invention is composed of a binder resin, a dispersion solvent and the like in addition to the N-type semiconductive particles such as the surface-treated titanium oxide.

  The ratio of the N-type semiconductive particles in the intermediate layer is preferably 1.0 to 2.0 times in terms of the volume ratio of the intermediate layer to the binder resin (when the volume of the binder resin is 1). By using the N-type semiconducting particles of the present invention at such a high density in the intermediate layer, the rectification of the intermediate layer is enhanced, and the increase in residual potential and dot image degradation are effective even when the film thickness is increased. Therefore, a good organic photoreceptor can be formed. Further, such an intermediate layer preferably uses 100 to 200 parts by volume of N-type semiconductive particles with respect to 100 parts by volume of the binder resin.

  On the other hand, the binder resin in which these particles are dispersed to form the layer structure of the intermediate layer is preferably a polyamide resin in order to obtain good dispersibility of the particles, but the polyamide resin shown below is particularly preferable.

  The binder resin for the intermediate layer 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 an alcohol-soluble polyamide resin, a copolymerized polyamide resin or a methoxymethylated polyamide resin composed of a chemical structure with few carbon chains between amide bonds such as 6-nylon described above is known. These resins have a high water absorption rate, and the intermediate layer using such a polyamide tends to be highly temperature and humidity dependent. As a result, for example, charging characteristics and sensitivity under high temperature and high humidity and low temperature and low humidity are likely to change. , Transfer memory is likely to occur.

  Alcohol-soluble polyamide resin improves the above-mentioned drawbacks and improves the disadvantages of conventional alcohol-soluble polyamide resins by giving the characteristics of heat of fusion 0-40 J / g and water absorption of 5% by mass or less. Even if the external environment changes or even if the organic photoreceptor is used continuously for a long time, a good electrophotographic image can be obtained.

  Hereinafter, the alcohol-soluble polyamide resin having a heat of fusion of 0 to 40 J / g and a water absorption of 5% by mass or less will be described.

  The alcohol-soluble polyamide resin is preferably a polyamide resin containing a repeating unit structure having 7 to 30 carbon atoms between amide bonds in an amount of 40 to 100 mol% of the entire repeating unit structure.

  Here, a repeating unit structure having 7 to 30 carbon atoms between amide bonds will be described. The repeating unit structure means an amide bond unit forming a polyamide resin. This is because a polyamide resin (type A) formed by condensation of a compound having a repeating unit structure having both an amino group and a carboxylic acid group, and a polyamide resin (type B) formed by condensation of a diamino compound and a dicarboxylic acid compound. ) In both examples.

  That is, the repeating unit structure of type A is represented by the general formula (3), and the carbon number contained in X is the carbon number of the amide bond unit in the repeating unit structure. On the other hand, the repeating unit structure of type B is represented by the general formula (4), and the number of carbon atoms contained in Y and the number of carbon atoms contained in Z are the number of carbon atoms of the amide bond unit in the repeating unit structure.

In general formula (3), R ₁ is a hydrogen atom, a substituted or unsubstituted alkyl group, X is a substituted or unsubstituted alkylene group, a group containing a divalent cycloalkane, a divalent aromatic group, and these A mixed structure is shown, and l is a natural number.

In general formula (4), R ₂ and R ₃ are each hydrogen atom, a substituted or unsubstituted alkyl group, Y and Z are each substituted or unsubstituted alkylene group, a group containing a divalent cycloalkane, and a divalent group. And m and n are natural numbers.

  As described above, the repeating unit structure having 7 to 30 carbon atoms includes a substituted or unsubstituted alkylene group, a group containing a divalent cycloalkane, a divalent aromatic group, and a chemical structure having a mixed structure thereof. Among them, a chemical structure having a group containing a divalent cycloalkane is preferable.

  The polyamide resin has 7 to 30 carbon atoms between amide bonds in the repeating unit structure, preferably 9 to 25, more preferably 11 to 20. The proportion of the repeating unit structure having 7 to 30 carbon atoms between amide bonds in the entire repeating unit structure is 40 to 100 mol%, preferably 60 to 100 mol%, more preferably 80 to 100 mol%.

  If the carbon number is less than 7, the hygroscopicity of the polyamide resin is large, the electrophotographic characteristics, particularly the humidity dependence of the potential during repeated use is large, and image defects such as black spots tend to occur, and the dot image Easy to deteriorate. If it is larger than 30, the dissolution of the polyamide resin in the coating solvent becomes worse, and it is not suitable for forming a coating film of the intermediate layer.

  Further, when the ratio of the repeating unit structure having 7 to 30 carbon atoms between amide bonds to the entire repeating unit structure is smaller than 40 mol%, the above effect is reduced.

  Preferred polyamide resins of the present invention include polyamides having a repeating unit structure represented by the following general formula (5).

In General Formula (5), Y ₁ represents a group containing a divalent alkyl-substituted cycloalkane, Z ₁ represents a methylene group, m represents 1 to 3, and n represents 3 to 20.

In the general formula (5), the group containing a divalent alkyl-substituted cycloalkane of Y ₁ preferably has the following chemical structure. That is, the polyamide resin of the present invention in which Y ₁ has the following chemical structure has a remarkable effect of preventing black spots and dot image deterioration.

In the above chemical structure, A represents a single bond and an alkylene group having 1 to 4 carbon atoms, R ₄ represents a substituent, represents an alkyl group, and p represents a natural number of 1 to 5. However, the plurality of R ₄ may be the same or different.

  Specific examples of the polyamide resin include the following examples.

  In the above specific examples, “%” in parentheses indicates the ratio (mol%) of the repeating unit structure having 7 or more carbon atoms between amide bonds in the repeating unit structure.

  Among the above specific examples, N-1 to N-4 polyamide resins having a repeating unit structure of the general formula (5) are particularly preferable.

  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. When the number average molecular weight is 5,000 or less, the uniformity of the film thickness of the intermediate layer is deteriorated, and the effects of the present invention are not sufficiently exhibited. On the other hand, if it is larger than 80,000, the solvent solubility of the resin is likely to be reduced, and an agglomerated resin is likely to be generated in the intermediate layer, which tends to cause black spots and deterioration of the dot image.

  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 produced by a general synthesis method of polyamide. However, an example of a synthesis example is given below.

As the solvent for dissolving the polyamide resin and preparing the coating solution, alcohols having 2 to 4 carbon atoms such as ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol, t-butanol, sec-butanol are preferable, It is excellent in the solubility of polyamide and the coating property 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.
The thickness of the intermediate layer of the present invention is preferably 0.3 to 10 μm. If the thickness of the intermediate layer is less than 0.5 μm, black spot is likely to occur and the dot image is likely to deteriorate. If it exceeds 10 μm, the residual potential is likely to increase, and the dot image tends to deteriorate. 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 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, and further 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%
If the volume resistance is less than 1 × 10 ⁸ , the charge blocking property of the intermediate layer decreases, the occurrence of black spots increases, the potential holding property of the organic photoreceptor deteriorates, and good image quality cannot be obtained. On the other hand, if it is greater than 10 ¹⁵ Ω · cm, the residual potential tends to increase in repeated image formation, and good image quality cannot 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 the intermediate layer has a charge generation function and a charge transport function in one layer, but more preferably the function of the photosensitive layer. The charge generation layer (CGL) and the charge transport layer (CTL) may be separated from each other. 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 organic photoreceptor of the present invention, it is preferable to use a charge generation material having high sensitivity characteristics in the wavelength region of 350 nm to 500 nm as the charge generation material. As such a charge generating substance, an azo pigment, a perylene pigment, a multisensitive quinone pigment, or the like is preferably used. These pigments can be used in combination. Examples of pigment compounds preferably used in the present invention are shown below.

  When a binder is used as the CGM dispersion medium in the charge generation layer, a known resin can be used as the binder, but the most preferred resins include formal resin, butyral resin, silicone resin, silicone-modified butyral resin, phenoxy resin, and the like. Can be mentioned. The ratio of the binder resin to the charge generating material is preferably 20 to 600 parts by mass with respect to 100 parts by mass of the binder resin. 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 As described above, in the present invention, the charge transport layer is preferably composed of a plurality of charge transport layers, and the uppermost charge transport layer contains the inorganic fine particles of the present invention.

  The charge transport layer contains a charge transport material (CTM) and a binder resin that disperses and forms a CTM. As other substances, additives such as an antioxidant may be contained in addition to the inorganic fine particles as necessary.

  As the charge transport material (CTM), the charge transport material of the above general formula (1) is used. Good. For example, a triphenylamine derivative, a hydrazone compound, a styryl compound, a benzidine compound, a butadiene compound, or the like can be used. 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. If the total film thickness is less than 10 μm, it is difficult to sufficiently obtain a latent image potential at the time of development, and image density is lowered and dot reproducibility is liable to be deteriorated. Diffusion of charge carriers generated in the generation layer) increases, and dot reproducibility tends to deteriorate. Further, the thickness of the charge transport layer serving as the surface layer is preferably 1.0 to 8.0 μm.

  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.

  Further, in the organic photoreceptor according to the present invention, it is preferable to dry the residual solvent in all layers constituting the photoreceptor to 5000 ppm or less. Furthermore, 3000 ppm or less is more preferable. If the residual solvent is too much, an active gas such as NOx is likely to enter the photosensitive layer, and image unevenness due to the occurrence of image blur or transfer memory is likely to occur.

  The amount of residual solvent is measured as follows.

  The entire layer structure is peeled off from the support of the photosensitive member, and in the photosensitive layer using pyrolysis gas chromatography (GC15A: manufactured by Shimadzu Corporation) and Curie Point Pyrolyzer (JHP-3S: manufactured by Nippon Analytical Industrial Co., Ltd.) The residual solvent amount of (all layers including the intermediate layer) is measured.

  Further, the coating solution for each layer is preferably filtered with a metal filter, a membrane filter or the like in order to remove foreign matters and aggregates in the coating solution before entering the coating step. For example, it is preferable to select a pleat type (HDC), a depth type (profile), a semi-depth type (profile star), etc., manufactured by Nippon Pole Co., Ltd. according to the characteristics of the coating solution and perform filtration.

  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. For forming the surface layer of the present invention, it is most preferable to use a circular slide hopper type coating apparatus.

  Among the above coating liquid supply type coating apparatuses, the coating method using a 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 organic photoreceptor of the present invention preferably contains 3 to 100 nm of inorganic fine particles together with the compound represented by the general formula (1). By incorporating inorganic fine particles on the surface of the organic photoreceptor, the wear resistance can be improved, and by using the charge transport material of the general formula (1), the inorganic fine particles are incorporated in the surface layer without deteriorating the dispersibility. Therefore, a surface layer having good transparency can be formed even for a short wavelength laser, and as a result, a high-definition electrophotographic image can be formed on the organic photoreceptor.

  The inorganic fine particles of the present invention are preferably metal oxides (including transition metal oxides) such as silica, titanium oxide, zinc oxide, and alumina. Of these, silica and titanium oxide are preferably used.

  These metal oxide particles are known to block the hydroxyl groups present on the surface and use them in the surface layer of the organophotoreceptor. In the present invention, the average blocking level of the hydroxyl groups is more complete. Therefore, the surface treatment of the inorganic fine particles is improved.

  The metal oxide particles are preferably fired and strengthened. For example, since silica that has not been subjected to firing strengthening is difficult to be hydrophobized, firing-strengthened silica is preferable as the silica that is subjected to the multiple surface treatments of the present invention. In order to give sufficient intensity | strength in a baking reinforcement | strengthening silica, what was baked at the temperature of 500 degreeC or more normally, Preferably 1000 degreeC or more is used. The firing time is preferably 5 hours or longer, more preferably 10 hours or longer. By firing the silica under the above temperature conditions, functional groups such as hydroxyl groups and silanol groups present on the surface of the silica particles are decomposed to form silicon oxide. As a result, the specific surface area of the silica particles is reduced, and when the surface is hydrophobized with a silane compound or the like, the surface treatment can be effectively performed. Specific examples of such silica include those produced by high-temperature hydrolysis in an oxygen bath of silicon tetrachloride.

  Fine particles having a number average primary particle size (Dp) of inorganic fine particles in the range of 3.0 to 100 nm are used. Particularly, 5 nm to 70 nm is preferable. The number average primary particle size (Dp) is a measured value as the average diameter in the ferret direction by image analysis, in which fine particles are magnified 10,000 times by observation with a transmission electron microscope, 100 particles are randomly observed as primary particles, and image analysis is performed. is there. Inorganic fine particles having a number average primary particle size (Dp) of less than 3.0 nm are difficult to uniformly disperse in the surface layer, tend to form aggregated particles, and the aggregated particles serve as charge traps to increase the residual potential. It tends to cause a decrease in image density and a deterioration in dot reproducibility. On the other hand, inorganic fine particles with a number average primary particle size (Dp) larger than 100 nm easily create large irregularities on the surface of the surface layer, and active gas (ozone and NOx) easily adheres to these large irregularities, resulting in image blurring and dot reproduction. Deterioration is likely to occur. In addition, inorganic fine particles having a number average primary particle size (Dp) larger than 100 nm are likely to precipitate in the dispersion and easily generate aggregates.

  In the present invention, the surface treatment of inorganic fine particles means that the surface of the inorganic fine particles is coated with a metal oxide, an organic compound, an organometallic compound, a fluorine compound, a reactive organosilicon compound, or the like. The surface of the inorganic fine particles is covered with a metal compound, an organic compound, an organometallic compound, a fluorine compound, a reactive organosilicon compound, or the like. Photoelectron spectroscopy (ESCA), Auger electron spectroscopy (Auger), secondary ion mass It is confirmed with high accuracy by using a combination of surface analysis methods such as analysis method (SIMS) and diffuse reflection FI-IR.

  The surface treatment of the inorganic fine particles can be performed by a wet method. For example, inorganic fine particles are dispersed in water to form an aqueous slurry, and this aqueous slurry is mixed with a water-soluble silicate, a water-soluble aluminum compound, or the like. When sodium silicate is used as the water-soluble silicate, it can be neutralized with an acid such as sulfuric acid, nitric acid or hydrochloric acid. On the other hand, when aluminum sulfate is used as the water-soluble aluminum compound, it can be neutralized with an alkali such as sodium hydroxide or potassium hydroxide. In the surface treatment with a reactive organosilicon compound, a solution obtained by dissolving or suspending a reactive organosilicon compound in an organic solvent or water is mixed with inorganic fine particles, and this solution is stirred for several minutes to about 1 hour. And depending on the case, after performing heat processing to this liquid, it can dry after passing through processes, such as filtration, and can obtain the inorganic fine particle which coat | covered the surface with the organosilicon compound. Surface treatment with a fluorine compound dissolves or suspends an organic silicon compound or the like having fluorine atoms in an organic solvent or water, mixes the suspension and inorganic fine particles, and stirs the mixed solution for a few minutes to an hour. After mixing and depending on the case, it is dried through a process such as filtration and coated with a fluorine compound. The multiple-surface-treated silica of the present invention improves the stability of the coating solution containing the particles by applying a surface treatment for improving dispersibility in a certain layer, and improves, for example, slipperiness and surface property in a certain layer. For this purpose, the slipperiness and surface properties are improved by treating with silicone oil or silicone resin.

  Preferable examples of the multiple surface treatments according to the present invention are oxide particles in which the primary treatment is a surface treatment with a halogenated silane and the final treatment is a surface treatment of a silazane compound.

  Oxide particles obtained by performing a surface treatment with a silicone oil as a primary treatment and a surface treatment with a silazane compound as a final treatment are also preferable. For example, a primary surface treatment is performed with a halogenated silane or a silicone oil-based treatment agent, the primary treatment powder is crushed, and the crushed powder is further subjected to a secondary surface treatment with an alkylsilazane-based treatment agent. Oxide particles having an improved hydrophobicity distribution can be obtained.

  The primary surface treatment with the halogenated silanes or the silicone oil-based treatment agent, and the secondary surface treatment with the alkylsilazane-based treatment agent after the crushing treatment may be either a dry treatment or a wet treatment. However, if the order of the primary surface treatment and the secondary surface treatment are different, or if the final treatment agent, amount used, treatment method, etc. are not appropriate, the hydrophobicity and hydrophobicity distribution cannot be improved. The object of the present invention cannot be achieved. In particular, when the final treatment is other than silazane compounds, the surface treatment tends to be detached with time and the hydrophobicity distribution tends to be large.

  By performing such surface treatment a plurality of times, the degree of hydrophobicity and the degree of hydrophobicity distribution of the oxide particles can be improved, and the occurrence of image density reduction and image blurring or dash marks can be effectively prevented. be able to.

  The inorganic fine particles in the surface layer according to the present invention preferably have a degree of hydrophobicity of 76% (vol.%) Or more. If the degree of hydrophobicity of the inorganic fine particles is less than 76% (vol.%), There are many hydroxyl groups present on the surface of the inorganic fine particles, the potential characteristics (charging potential, residual potential, etc.) are highly dependent on humidity, NOx, etc. The active gas is easily adsorbed on the surface, and image blurring and dash marks are likely to occur. The degree of hydrophobicity of the inorganic fine particles is more preferably 80% or more.

  The inorganic fine particles in the surface layer according to the present invention preferably have a hydrophobicity distribution value of 10% (vol.%) Or less. When the hydrophobicity distribution value is larger than 10% (vol.%), Inorganic fine particles having many hydroxyl groups remaining on the surface are included, and image blurring is likely to occur.

  The degree of hydrophobicity (methanol wettability) of the present invention is indicated by a measure of wettability with respect to methanol. That is, it is defined as follows.

Hydrophobicity (methanol wettability) = (a / (a + 50)) × 100
The method for measuring the degree of hydrophobicity is described below.

  0.2 g of inorganic fine particles to be measured are weighed and added to 50 ml of distilled water in a 200 ml beaker. Methanol is slowly added dropwise from a burette whose tip is immersed in a liquid until the whole of the inorganic fine particles are wetted (until all settles) in a state of slow stirring. When the amount of methanol necessary to wet the entire inorganic fine particles is a (ml), the degree of hydrophobicity is calculated by the above formula.

Method of measuring hydrophobicity distribution value 1) Weigh 0.2 g of inorganic fine particles to be measured and put into a centrifuge tube.

(Prepare one for each point you want to plot)
2) Put methanol solutions of different concentrations into each 7 ml centrifuge tube with Komagome pipette and tighten (use the methanol concentration determined by the above hydrophobization degree for total precipitation).

  3) Disperse at 90 rpm with a tumbler mixer for 30 seconds.

4) Centrifuge (3500 rpm, 10 minutes)
5) Read the sedimentation volume, and determine each sedimentation volume% when the total sedimentation volume (the total sedimentation volume) is 100%.

  6) Based on the above measured values, a graph of the horizontal axis methanol concentration (Vol.%) And the vertical axis sedimentation volume (Vol.%) Is prepared.

  From the above measurement, the hydrophobicity distribution is measured, and the hydrophobicity distribution value is defined as follows.

{(Methanol Vol.% With a sedimentation volume of 100%)
-(Methanol Vol.% With a sedimentation volume of 10%)} ≦ 25
The hydrophobization degree distribution curve is shown in FIG. In the distribution curve of FIG. 4, the methanol concentration at point a represents the degree of hydrophobicity, the difference between the methanol concentration at point a and the methanol concentration at point b; Δ (ab) represents the hydrophobicity distribution value of the present invention. .

  Next, the surface treatment agent used for the primary surface treatment or the secondary surface treatment of the present invention will be described.

  Examples of the silicone oil-based treating agent preferably used in the primary treatment of the present invention include straight silicone oils such as dimethyl silicone oil, methylphenyl silicone oil, and methylhydrogen silicone oil, amino-modified silicone oil, epoxy-modified silicone oil, and carboxyl-modified silicone oil. , Carbinol-modified silicone oil, methacryl-modified silicone oil, mercapto-modified silicone oil, phenol-modified silicone oil, one-end reactive modified silicone oil, heterogeneous functional group-modified silicone oil, polyether-modified silicone oil, methylstyryl-modified silicone oil, alkyl Modified silicone oil, higher fatty acid ester modified silicone oil, hydrophilic special modified silicone oil, Kokishi modified silicone oil, higher fatty acid containing modified silicone oil, it is possible to use modified silicone oils and fluorine modified silicone oil. Moreover, you may mix 2 or more types according to the objective.

  Examples of halogenated silanes include dimethyldichlorosilane, monochlorosilane, dichlorosilane, trichlorosilane, and tetrachlorosilane.

  Silazanes used in the final surface treatment agent include hexamethyldisilazane, hexaethyldisilazane, hexapropyldisilazane, hexabutyldisilazane, hexapentyldisilazane, hexahexyldisilazane, hexacyclohexyldisilazane, Hexaphenyldisilazane, divinyltetramethyldisilazane, dimethyltetravinyldisilazane, etc. can be used.

In addition to the above silicone oil-based treatment agents and halogenated silanes, the following alkoxysilanes, siloxanes, metal alkoxides, fatty acids and metal salts thereof are used as surface treatment agents before the final surface treatment of silazanes. May be.
Alkoxysilanes include tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, methyltriethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, o-methylphenyltrimethoxysilane, p-methylphenyltri Methoxysilane, n-butyltrimethoxysilane, i-butyltrimethoxysilane, hexyltrimethoxysilane, octyltrimethoxysilane, decyltrimethoxysilane, dodecyltrimethoxysilane, tetraethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane , Phenyltriethoxysilane, diphenyldiethoxysilane, i-butyltriethoxysilane, decyltriethoxysilane, vinyltriethoxysilane, γ Methacryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-chloropropyltrimethoxysilane, γ-aminopropyltrimethoxysilane Γ-aminopropyltriethoxysilane, γ- (2-aminoethyl) aminopropyltrimethoxysilane, γ- (2-aminoethyl) aminopropylmethyldimethoxysilane, and the like.

  Examples of siloxanes include siloxanes such as hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, hexamethyldisiloxane, and octamethyltrisiloxane.

  Metal alkoxides include trimethoxyaluminum, triethoxyaluminum, tri-i-propoxyaluminum, tri-n-butoxyaluminum, tri-s-butoxyaluminum, tri-t-butoxyaluminum, mono-s-butoxydi-i-propyl Aluminum, tetramethoxy titanium, tetraethoxy titanium, tetra-i-propoxy titanium, tetra-n-propoxy titanium, tetra-n-butoxy titanium, tetra-s-butoxy titanium, tetra-t-butoxy titanium, tetraethoxy zirconium, tetra -I-propoxyzirconium, tetra-n-butoxyzirconium, dimethoxytin, diethoxytin, di-n-butoxytin, tetraethoxytin, tetra-i-propoxytin, tetra-n-butoxytin, dietoxy Zinc, magnesium methoxide, magnesium ethoxide, magnesium isopropoxide, and the like.

Fatty acids and their metal salts include undecyl acid, lauric acid, tridecyl acid, dodecyl acid, myristic acid, palmitic acid, pentadecylic acid, stearic acid, heptadecylic acid, arachidic acid, montanic acid, oleic acid, linoleic acid, arachidonic acid, etc. The long-chain fatty acid is a salt of a metal such as zinc, iron, magnesium, aluminum, calcium, sodium, or lithium.
These treatment agents may be used by diluting with hexane, toluene, alcohol (methanol, ethanol, propanol, etc.), acetone, or the like, depending on circumstances.

  Specific procedures for surface treatment; for example, silica powder is placed in a solvent in which silicone oil is dissolved (preferably adjusted to pH 4 with an organic acid or the like), and then reacted, and then the solvent is removed and pulverization is performed. . Thereafter, the pulverized treated powder is put into a solvent in which the silazane compound is dissolved and reacted, and then the solvent is removed and pulverization is performed. Further, the following method may be used. For example, put silica powder in a reaction vessel, add alcohol water while stirring in a nitrogen atmosphere, introduce a silicone oil treatment liquid such as organopolysiloxane into the reaction vessel, perform surface treatment, and further heat and stir. Remove the solvent. Then, after crushing treatment, while stirring in a nitrogen atmosphere, an alkylsilazane-based treatment solution is introduced to perform surface treatment, and further heated and stirred to remove the solvent and then cooled. The treatment conditions are adjusted so that the silica powder has the hydrophobicity, the degree of hydrophobicity and the distribution frequency.

  In addition, these treatment agents can be used by diluting with hexane, toluene, alcohol (methanol, ethanol, propanol, etc.), acetone, etc., or with water depending on the case.

  The surface layer contains a binder resin that helps dispersibility of the inorganic fine particles. As the binder resin, polycarbonate and polyarylate are preferable. The molecular weight of these polycarbonates and polyarylates is preferably 10,000 to 100,000.

  The ratio of the inorganic particles in the surface layer is preferably at least 5 parts by mass and not more than 50 parts by mass with respect to 100 parts by mass of the binder resin. If the amount is less than 5 parts by mass, the surface layer is greatly worn, and scratches or the like are generated, so that the halftone image tends to be rough. When the amount is more than 50 parts by mass, the surface layer becomes a fragile film, and cracks and the like are likely to occur.

  The surface layer of the photoreceptor according to the present invention preferably contains an antioxidant. The surface layer is easily oxidized by an active gas such as NOx or ozone during charging of the photoconductor, and image blur is likely to occur. However, the presence of an antioxidant can prevent image blur. Typical examples of the antioxidants are those that prevent the action of oxygen under conditions of light, heat, discharge, etc. on auto-oxidizing substances present in the organic photoreceptor or on the surface of the organic photoreceptor, It is a substance that has the property of inhibiting. Typical examples include the following compound groups.

  Further, it is preferable that the uppermost layer of the photoreceptor according to the present invention contains a fluorine-containing resin fine particle. By including the fluororesin fine particles in the resurface layer, the transferability of the toner image formed on the surface of the photoreceptor to recording paper or the like is improved, and the reproducibility of the dot image is improved.

  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, Dichloromethane, 1, 2- dichloroethane, methyl ethyl ketone, etc. are used preferably. These solvents may be used alone or as a mixed solvent of two or more.

  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 including the illumination lamp and the first mirror constituting the scanning optical system, and the V-shaped first image is located. Reading is performed by the movement of the second mirror unit 16 including 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 as a transferring means (transfer process), cleaning device (cleaning process) 26 for the photosensitive member 21, and light neutralizing means (light slow charge). PCL (precharge lamp) 27 as a process is 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. As the photosensitive member 21, the organic photosensitive member according to the present invention is used, and the photosensitive member 21 is driven and rotated in the clockwise direction shown in the drawing.

  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.

  In the image forming apparatus of the present invention, a semiconductor laser or a light emitting diode having an oscillation wavelength of 350 to 500 nm is used 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 (Ld: measured at the maximum position) along the main scanning direction 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 a solid scanner such as the scanning optical system and LED using a semiconductor laser, there is a Gaussian distribution and Lorentz distribution, etc. 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 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.

<toner>
The electrostatic latent image formed on the organic photoreceptor of the present invention is visualized as a toner image by development. The toner used for development may be a pulverized toner or a polymerized toner, but the toner according to the present invention is preferably a polymerized toner that can be prepared by a polymerization method from the viewpoint of obtaining a stable particle size distribution.

  The term “polymerized toner” means a toner in which a toner binder resin is formed and the toner shape is formed by polymerization of a raw material monomer of the binder resin and, if necessary, subsequent chemical treatment. More specifically, it means a toner formed through a polymerization reaction such as suspension polymerization or emulsion polymerization, and if necessary, a step of fusing particles between them.

  The volume average particle diameter of the toner, that is, the 50% volume particle diameter (Dv50) is preferably 2 to 9 μm, more preferably 3 to 7 μm. By setting this range, the resolution can be increased. In addition, by combining with the above range, the amount of toner having a fine particle diameter can be reduced while being a small particle diameter toner, the dot image reproducibility is improved over a long period of time, and the sharpness is excellent. In addition, a stable image can be formed.

<Developer>
The toner according to the present invention may be used as a one-component developer or a two-component developer.

  When used as a one-component developer, a non-magnetic one-component developer or a magnetic one-component developer containing about 0.1 to 0.5 μm of magnetic particles in the toner can be used. be able to.

  Further, it can be mixed with a carrier and used as a two-component developer. In this case, conventionally known materials such as metals such as iron, ferrite and magnetite, and alloys of these metals with metals such as aluminum and lead can be used as the magnetic particles of the carrier. Ferrite particles are particularly preferable. The magnetic particles preferably have a volume average particle size of 15 to 100 μm, more preferably 25 to 80 μm.

  The volume average particle diameter of the carrier can be typically measured by a laser diffraction particle size distribution measuring apparatus “HELOS” (manufactured by SYMPATEC) equipped with a wet disperser.

  The carrier is preferably a carrier in which magnetic particles are further coated with a resin, or a so-called resin dispersion type carrier in which magnetic particles are dispersed in a resin. The resin composition for coating is not particularly limited, and for example, olefin resin, styrene resin, styrene-acrylic resin, silicone resin, ester resin, or fluorine-containing polymer resin is used. In addition, the resin for constituting the resin-dispersed carrier is not particularly limited, and a known resin can be used. For example, a styrene-acrylic resin, a polyester resin, a fluorine resin, a phenol resin, or the like is used. be able to.

  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 toner image on the photosensitive member 21 is transferred to the transfer paper P while being transferred to 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. Is, 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. In addition, a process cartridge is formed by integrally supporting at least one of a charger, an image exposure device, a developing device, a transfer or separation device, and a cleaning device together with a photosensitive member, 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. It comprises a paper conveying means 21 and a fixing means 24. A document image reading device SC is disposed on the upper part of 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 and 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 means 3Y performs exposure based on the image signal (yellow) on the photosensitive drum 1Y given a uniform potential by the charger 2Y, and forms 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. In addition, 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 cleaning means 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 exposure 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 first color yellow toner image is not affected by the second to fourth developing units.

  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 photoreceptor 1 is applied to the intermediate transfer body 70 from the primary transfer roller 5a in the process of passing through the nip portion between the photoreceptor 1 and the intermediate transfer body 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 photosensitive member 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 heated and fixed.

  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, the aspect of this invention is not limited to this. In the following text, “part” means “part by mass”.

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.

  The following intermediate layer dispersion is diluted twice with the same mixed solvent, and is allowed to stand overnight and then filtered (filter; rigesh mesh filter made by Nippon Pole Co., Ltd., nominal filtration accuracy: 5 microns, pressure: 50 kPa). Produced.

(Preparation of intermediate layer dispersion)
Binder resin: (Exemplary polyamide N-1) 1 part Rutile-type titanium oxide (primary particle size 35 nm; titanium oxide pigment prepared by surface treatment with dimethylpolysiloxane having a hydroxyl group at the terminal and having a hydrophobicity of 33) 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. Produced.

Charge generation layer: CGL
Charge generation material (CGM): Exemplified compound CGM-2 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 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 1 (CTL1)
Charge transport material (Exemplary Compound CTM-2) 225 parts Polycarbonate (Z300: manufactured by Mitsubishi Gas Chemical Company) 300 parts Antioxidant (Irganox 1010: manufactured by Ciba Geigy Japan) 6 parts Dichloromethane 2000 parts Silicon oil (KF-54: Shin-Etsu Chemical Co., Ltd.) Product) 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 110 ° C. for 70 minutes to form a charge transport layer 1 having a dry film thickness of 18.0 μm.

Charge transport layer 2 (CTL2)
Inorganic fine particles: silica particles (primary treatment: dimethyldichlorosilane, secondary treatment: silica treated with hexamethyldisilazane and having an average primary particle size of 8 nm: hydrophobization degree 76, hydrophobization degree distribution value 10) 60 parts Charge transport Substance (Exemplary Compound CTM-2) 150 parts Polycarbonate (Z300: manufactured by Mitsubishi Gas Chemical Company) 300 parts Exemplary Compound AO-1 12 parts THF: Tetrahydrofuran 2800 parts Silicon oil (KF-54: manufactured by Shin-Etsu Chemical Co., Ltd.) 4 parts mixed Then, the charge transport layer coating solution 2 was prepared by dispersing and dissolving. This coating solution is applied onto the charge transport layer 1 with a circular slide hopper coater, dried at 110 ° C. for 70 minutes to form a charge transport layer 2 having a dry film thickness of 2.0 μm, and the photoreceptor 1 is formed. Produced. The residual solvent in all layers of the photoreceptor 1 was 3600 ppm.

Production of photoconductors 2 to 10 In production of photoconductor 1, the types of polyamide resin of the intermediate layer, charge generation material, charge transport material of charge transport layers 1 and 2, and inorganic fine particles of charge transport layer 2 are as shown in Table 1. Photoconductors 2 to 10 were produced in the same manner as Photoconductor 1 except that the change was made. However, the photoreceptor 10 was prepared without containing inorganic fine particles in the charge transport layer 2.

Production of Photoreceptor 11 Photoreceptor 11 was produced in the same manner as in the production of photoreceptor 10, except that the charge transport material of charge transport layers 1 and 2 was changed to the following benzidine compound.

  In Table 1, inorganic fine particles 1 represent silica, inorganic fine particles 2 represent alumina, and inorganic fine particles 3 represent titanium oxide. Moreover, about the surface treatment agent of an inorganic fine particle, the surface treatment using the following surface treatment agent is shown.

Silazane; Hexamethyldisilazane Silicone oil; Methyl hydrogen silicone oil The hydrophobicity and the hydrophobicity distribution value of the inorganic fine particles used in the photoreceptors 1 to 13 are 20 ° C. and 60% RH environment after the surface treatment of the inorganic fine particles. It is a value measured by the measurement method described above after storage for 3 days (after 3 days of NN).

  A toner used in the present invention and a developer using the toner were prepared.

  Next, a toner was prepared as follows.

* Production of Toner 1-Bk, Toner 1-Y, Toner 1-M, and Toner 1-C Sodium n-dodecyl sulfate = 0.90 kg and 10.0 L of pure water are added and dissolved with stirring. While stirring, 1.20 kg of Legal 330R (carbon black manufactured by Cabot) was gradually added to this liquid, and then continuously dispersed for 20 hours using a sand grinder (medium type disperser). After dispersion, the particle size of the dispersion was measured using an electrophoretic light scattering photometer ELS-800 manufactured by Otsuka Electronics Co., Ltd. As a result, the weight average particle size was 122 nm. Moreover, the solid content concentration of the dispersion measured by a mass method by standing drying was 16.6% by mass. This dispersion is referred to as “colorant dispersion 1”.

  0.055 kg of sodium dodecylbenzenesulfonate is mixed with 4.0 L of ion-exchanged water and dissolved by stirring at room temperature. This is referred to as an anionic surfactant solution A.

  0.014 kg of nonylphenyl alkyl ether is mixed with 4.0 L of ion-exchanged water and dissolved by stirring at room temperature. This is designated as a nonionic surfactant solution A.

  Potassium persulfate = 223.8 g is mixed with 12.0 L of ion-exchanged water and dissolved with stirring at room temperature. This is referred to as initiator solution A.

  In a 100 L reaction kettle equipped with a temperature sensor, a cooling pipe, and a nitrogen introducing device, 3.41 kg of a polypropylene emulsion having a number average molecular weight (Mn) of 3500, an anionic surfactant solution A, and a nonionic surfactant solution A were added. Start agitation. Then, 44.0 L of ion exchange water is added.

  When heating is started and the liquid temperature reaches 75 ° C., the initiator solution A is added in its entirety. Thereafter, while controlling the liquid temperature at 75 ° C. ± 1 ° C., 14.3 kg of styrene, 2.88 kg of n-butyl acrylate, 0.8 kg of methacrylic acid, and 548 g of t-dodecyl mercaptan are charged.

  Furthermore, the liquid temperature was raised to 80 ° C. ± 1 ° C., and stirring was performed for 6 hours. Cool the liquid temperature below 40 ° C and stop stirring. It filtered with the pole filter and this was set as latex A1.

  The glass transition temperature of the resin particles in the latex A1 was 59 ° C., the softening point was 116 ° C., the molecular weight distribution was weight average molecular weight = 13.4 million, and the weight average particle size was 125 nm.

  Potassium persulfate = 200.7 g is mixed with 12.0 L of ion-exchanged water, and dissolved with stirring at room temperature. This is designated initiator solution B.

  The nonionic surfactant solution A is put into a 100 L reaction kettle equipped with a temperature sensor, a cooling pipe, a nitrogen introducing device, and a comb baffle, and stirring is started. Next, 44.0 L of ion exchange water is added.

  Heating is started, and when the liquid temperature reaches 70 ° C., the initiator solution B is added. At this time, a solution prepared by previously mixing 11.0 kg of styrene, 4.00 kg of n-butyl acrylate, 1.04 kg of methacrylic acid, and 9.02 g of t-dodecyl mercaptan is added.

  Thereafter, the liquid temperature was controlled to 72 ° C. ± 2 ° C., and the mixture was heated and stirred for 6 hours. Furthermore, the liquid temperature was raised to 80 ° C. ± 2 ° C., and the mixture was heated and stirred for 12 hours.

  Cool the liquid temperature below 40 ° C and stop stirring. It filtered with the pole filter and this filtrate was set to latex B1.

  The glass transition temperature of the resin particles in the latex B1 was 58 ° C., the softening point was 132 ° C., the molecular weight distribution was weight average molecular weight = 245,000, and the weight average particle size was 110 nm.

  Sodium chloride = 5.36 kg as salting-out agent and 20.0 L of ion-exchanged water are added and dissolved by stirring. This is designated as sodium chloride solution A.

  The latex A1 = 20.0 kg and latex B1 = 5.2 kg prepared above and the colorant dispersed in a 100 L SUS reaction kettle equipped with a temperature sensor, cooling pipe, nitrogen introducing device and comb baffle (stirring blade is an anchor blade) Liquid 1 = 0.4 kg and ion-exchanged water 20.0 kg are added and stirred. Then warm to 35 ° C. and add sodium chloride solution A. Thereafter, after standing for 5 minutes, the temperature rise is started, and the temperature is raised to a liquid temperature of 85 ° C. in 5 minutes (temperature rise rate = 10 ° C./min). The mixture is heated and stirred at a liquid temperature of 85 ° C. ± 2 ° C. for 6 hours to cause salting out / fusion. Then, it cools to 30 degrees C or less and stops stirring. The mixture is filtered through a sieve having an opening of 45 μm, and this filtrate is used as an association liquid. Subsequently, using a centrifuge, wet cake-like non-spherical particles were collected from the associated liquid by filtration. Thereafter, it was washed with ion exchange water.

  The wet cake-like colored particles that had been washed as described above were dried with hot air at 40 ° C. to obtain colored particles. Further, careful classification was performed with an air classifier to obtain colored particles having a 50% volume particle diameter (Dv50) of 4.2 μm. Furthermore, 1.0% by mass of hydrophobic silica (hydrophobic degree = 70, number average primary particle size = 12 nm) was added to the colored particles, and “toner 1” having a 50% volume particle size (Dv50) of 4.2 μm was added. Bk "was obtained.

  In the production of toner 1-Bk, C.I. I. “Toner 1-Y” having a 50% volume particle size (Dv50) of 4.8 μm was obtained in the same manner except that 8 parts of Pigment Yellow 185 was used.

  In the production of toner 1-Bk, C.I. I. “Toner 1-M” having a 50% volume particle size (Dv50) of 4.3 μm was obtained in the same manner except that 10 parts of Pigment Red 122 was used.

  In the production of toner 1-Bk, C.I. I. “Toner 1-C” having a 50% volume particle size (Dv50) of 4.9 μm was obtained in the same manner except that 5 parts of Pigment Blue 15: 3 was used.

  The 50% volume particle diameter (Dv50) of the toner can be measured using a Coulter Counter TAII. In the Coulter counter TAII, an aperture diameter = 100 μm is used and measured using a particle size distribution in the range of 2.0 to 40 μm.

Preparation of Developer A ferrite carrier having a 50% volume particle diameter (Dv50) of 45 μm coated with a silicone resin is mixed with each of the above toners, that is, toner 1-Bk to toner 1-C (a total of four toners). A developer having a toner concentration of 6% was prepared for evaluation. These four types of developers are designated as developer 1-Bk to developer 1-C, corresponding to the toner.

  The 50% volume particle size (Dv50) of the carrier is typically measured by a laser diffraction particle size distribution measuring device “HELOS” (manufactured by SYMPATEC) equipped with a wet disperser. Can do.

<< Evaluation 1 >>
As shown in Table 2, the photoconductor and toner are combined and mounted on a commercially available full-color multifunction device 8050 (manufactured by Konica Minolta Business Technologies Co., Ltd.) basically having the configuration shown in FIG. Using a short wavelength laser light source, sharpness evaluation and durability test were performed. Specifically, a total of 20,000 character images and halftone images were printed and evaluated at the start and every 5000 sheets. Evaluation items and evaluation criteria are shown below. An A4 image having a white background, a solid black portion, a solid image portion of red, green, and blue, and a character image portion was printed on the original image.

Evaluation condition Photoconductor linear velocity: 220 mm / sec
Image Evaluation Dot Reproducibility A halftone image was prepared and evaluated by changing the exposure diameter of the laser beam at the start of evaluation and using exposure diameters (Ld) of 13 μm, 21 μm, and 43 μm in the writing principal direction.

  A: Halftone images of 600 dpi, 1200 dpi, and 2400 dpi are reproduced clearly (each dot is independent) (high image quality characteristics are very good).

  ○: 600 dpi and 1200 dpi halftone images are clearly reproduced, but the 2400 dpi halftone images have insufficient clarity (independence of each dot) (good image quality characteristics).

  Δ: A halftone image of 600 dpi is clearly reproduced, but the halftone images of 1200 and 2400 dpi are not sufficiently clear (re-evaluation of high image quality characteristics is necessary).

Rank D: Insufficient clarity (independence of each dot) even with a halftone image of 600 dpi (insufficient image quality)
At the start of image density evaluation, the exposure diameter of the laser beam was changed, and the exposure diameters in the writing direction were 13 μm, 21 μm, and 43 μm, and the densitometer “RD-918” (manufactured by Macbeth) ), And the image density was measured at a relative density with the density of the printer paper set to 0.0. Further, the following residual potential was obtained from the difference in surface potential after light neutralization between the start and the 20,000th printing.

A: The increase in residual potential at each exposure diameter is less than 50 V, and the image density is 1.3 or more / good. ○: The increase in residual potential is 50 V to 120 V at at least one exposure diameter, and the image density is 1. 0 or more to less than 1.3 / a level that causes no problem in practical use ×: At least one exposure diameter, the increase in the residual potential is 121 V or more, and the image density is less than 1.0 / there is a problem in practical use. )Evaluation of)
After printing 20,000 sheets by the above-described full-color multifunction device 8050 remodeling machine, the occurrence of streak density unevenness due to surface flaws on the photoreceptor was observed with a halftone image, and evaluated according to the following evaluation criteria.

A: There is almost no surface damage on the photoconductor, and no streak density unevenness is observed in the halftone image (good).
◯: The surface scratches on the photoreceptor are weak, and streak image unevenness with a density difference of less than 0.05 occurs in the halftone image, but the density difference is not so noticeable in the halftone image. (Practical problem level)
X: The surface flaw of the photoconductor is clear, the stripe density unevenness having a density difference of 0.05 or more occurs in the halftone image, and the density difference is clear in the halftone image. (There are practical problems)
Color reproducibility At the start of evaluation, the exposure diameter of the laser beam is changed, and the exposure diameters in the writing direction are 13 μm, 21 μm, and 43 μm, and Y, M, and C of the first image and the 100th image The color of the solid image portion of the secondary color (red, blue, green) in the toner is measured by “Macbeth Color-Eye 7000”, and the first and 100th sheets of each solid image are measured using the CMC (2: 1) color difference formula. The color difference of was calculated.

A: Color difference is 3 or less (good) in all dot images with exposure diameters of 13 μm, 21 μm and 43 μm
○: Color difference is 3 or less (possible for practical use) in dot images with exposure diameters of 21 and 43 μm
×: When the color difference is larger than 3 / practical problem (not practical)
The evaluation results are shown in Table 2 below.

  As is clear from Table 2, the organic photoreceptors 1 to 10 using the charge transport material of the general formula (1) have stable reproducibility of small dots in short-wavelength laser exposure, and are halftone images and images. The density and color reproducibility are also good. On the other hand, the photoreceptor using the CTMR-1 charge transport material outside the present invention of Comparative Example 1 has a large deterioration in dot reproducibility, and the evaluation of the stripe density unevenness of the halftone image is also inferior. Color reproducibility is also degraded.

<< Evaluation 2 >>
Evaluation was performed in the same manner as in Evaluation 1 except that the oscillation wavelength of the semiconductor laser of the exposure device was changed from the short wavelength laser of 405 nm to the short wavelength laser of 480 nm among the evaluation conditions performed in Evaluation 1. The evaluation result of evaluation 2 was almost the same as the evaluation result of evaluation 1.

<< Evaluation 3 >>
Evaluation was performed in the same manner as in Evaluation 2 except that the semiconductor laser of the exposure device was changed to a light emitting diode (oscillation wavelength: 380 nm) under the evaluation conditions in Evaluation 2. Even when the light emitting diode was used as the image exposure light source, the evaluation results were almost the same as those in Evaluation 2.

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. It is a figure of a hydrophobization degree distribution curve.

Explanation of symbols

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 (14)

In an organic photoconductor used in an image forming method having an exposure step of forming an electrostatic latent image using a semiconductor laser having an oscillation wavelength of 350 to 500 nm or a light source of a light emitting diode on the organic photoconductor, And a photosensitive layer, and the photosensitive layer contains a charge transport material represented by the following general formula (1).

[In General Formula (1), Ar ₁ and Ar ₂ each represents an alkyl group, an aralkyl group, an aryl group, a biphenyl group, or a heterocyclic group, which may have a substituent, and R ₁ , R ₂ , R ₃ and R ₄ each represent a hydrogen atom, an alkyl group, an alkoxy group or a halogen atom; X represents —O—, —S— or — (R ₅ ) C (R ₆ ) —, (R ₅ and R ₆ each represent Represents a hydrogen atom, an alkyl group or an aryl group which may have a substituent. The organophotoreceptor according to claim 1, wherein the photosensitive layer has a charge generation layer containing a charge generation material and a charge transport layer containing a charge transport material. 3. The organophotoreceptor according to claim 1 or 2, wherein the charge transport material of the general formula (1) has a molecular weight of 500 to 1500. The organophotoreceptor according to claim 1, wherein the charge transport layer contains inorganic fine particles having a number average primary particle size (Dp) of 3 to 100 nm. The charge transport layer is composed of a plurality of charge transport layers, and the uppermost charge transport layer contains the charge transport material of the general formula (1) and inorganic fine particles. The organophotoreceptor according to claim 1. The organophotoreceptor according to claim 2, wherein the charge generation material is a polycyclic quinone compound. The organophotoreceptor according to claim 2, wherein the charge generation material is a perylene-based compound. 8. The organophotoreceptor according to claim 2, further comprising an intermediate layer containing N-type semiconductive particles between the conductive support and the charge generation layer. The organophotoreceptor according to claim 8, wherein the N-type semiconductor particles are titanium oxide. The organophotoreceptor according to claim 9, wherein the titanium oxide is a rutile titanium oxide pigment or an anatase titanium oxide pigment. The organophotoreceptor according to claim 8, wherein the intermediate layer contains a binder of polyamide resin. The organophotoreceptor according to claim 11, wherein the polyamide resin is a polyamide resin having a heat of fusion of 0 to 40 J / g and a water absorption of 5% by mass or less. Development that has an exposure step of forming an electrostatic latent image on an organic photoreceptor using a semiconductor laser having an oscillation wavelength of 350 to 500 nm or a light source of a light emitting diode, and developing the electrostatic latent image into a toner image In the image forming method comprising the steps, the organic photoreceptor has a photosensitive layer on a conductive support, and the photosensitive layer contains a charge transport material represented by the following general formula (1): .

[In General Formula (1), Ar ₁ and Ar ₂ each represents an alkyl group, an aralkyl group, an aryl group, a biphenyl group, or a heterocyclic group, which may have a substituent, and R ₁ , R ₂ , R ₃ and R ₄ each represent a hydrogen atom, an alkyl group, an alkoxy group or a halogen atom; X represents —O—, —S— or — (R ₅ ) C (R ₆ ) —, (R ₅ and R ₆ each represent Represents a hydrogen atom, an alkyl group or an aryl group optionally having substituent (s)] Development having an exposure means for forming an electrostatic latent image on an organic photoreceptor using a semiconductor laser having an oscillation wavelength of 350 to 500 nm or a writing light source of a light emitting diode, and developing the electrostatic latent image into a toner image In the image forming apparatus having the above-mentioned means, the organic photoreceptor has a photosensitive layer on a conductive support, and the photosensitive layer contains a charge transport material of the following general formula (1). .

[In General Formula (1), Ar ₁ and Ar ₂ each represents an alkyl group, an aralkyl group, an aryl group, a biphenyl group, or a heterocyclic group, which may have a substituent, and R ₁ , R ₂ , R ₃ and R ₄ each represent a hydrogen atom, an alkyl group, an alkoxy group or a halogen atom; X represents —O—, —S— or — (R ₅ ) C (R ₆ ) —, (R ₅ and R ₆ each represent Represents a hydrogen atom, an alkyl group or an aryl group which may have a substituent.

Images