JP2006038918A - Organophotoreceptor, image forming apparatus and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organophotoreceptor which prevents degradation of a halftone image and also prevents occurrence of a dash mark, transfer memory and spots by simultaneously satisfying such incompatible properties of an organophotoreceptor as property of resisting adhesion of a foreign substance and wear resistance and configuring a photoreceptor surface such that a foreign substance adheres hardly and a scratch hardly becomes a clear image, and to provide an image forming apparatus and an image forming method using the organophotoreceptor. <P>SOLUTION: The organophotoreceptor contains a compound represented by formula (1) wherein R<SB>1</SB>represents a 2-5C alkyl. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an organic photoreceptor used for electrophotographic image formation (hereinafter also simply referred to as a photoreceptor), an image forming apparatus and an image forming method using the organic photoreceptor, and more specifically, to a copying machine or a printer. The present invention relates to an organic photoreceptor used for electrophotographic image formation used in the field, an image forming apparatus and an image forming method using the organic photoreceptor.

  In recent years, organic photoreceptors have been widely used for electrophotographic photoreceptors. Organic photoreceptors have advantages over other photoreceptors, such as easy development of materials suitable for various exposure light sources from visible light to infrared light, the ability to select materials that are free from environmental pollution, and low manufacturing costs. However, there are disadvantages such as low mechanical strength and easy adhesion of foreign matter, poor chemical durability, deterioration of electrostatic characteristics of a photoreceptor when many sheets are printed, and generation of scratches on the surface.

  That is, the organic photoconductor is a surface generated by a mechanical external force applied when a toner image formed on the photoconductor is transferred to a transfer material such as paper or when residual toner on the photoconductor is cleaned. Durability (abrasion resistance) against foreign matter adhesion and scratches is required.

That is, the problem that the wear resistance property against contact friction by the cleaning means or the like is insufficient, the surface layer is worn by copying a large number of sheets, and the film thickness is not sufficiently solved yet. That is, as the surface layer is worn, streak-like scratches are generated on the surface of the photoreceptor, and the scratches are reflected in the electrophotographic image, resulting in streaks due to the entire surface of the halftone image, resulting in a rough image. Cheap.

  On the other hand, recent electrophotographic image forming apparatuses tend to be used as information equipment for printing out image information produced by a computer, and there are copying machines and printers capable of forming high-quality digital images. It has been demanded. Therefore, there is a need for a developing means that faithfully visualizes the electrostatic latent image formed on the organophotoreceptor. As one of the means, a polymerized toner having a uniform shape factor and particle size distribution is developed. It has been proposed to use as a means (Patent Document 1). However, even when the toner capable of faithfully reproducing the electrostatic latent image is used, if the electrostatic latent image is formed on the organic photoreceptor whose surface is rough due to the scratch or the like, the formation of the electrostatic latent image itself A problem has been found that the characteristics of the polymerized toner, which is reproduced as a toner image in which the roughness is enlarged and the roughness is enlarged, and the shape factor and the particle size distribution are improved, are not sufficiently exhibited.

  In order to prevent such wear deterioration of the surface layer, the charge transport layer binder is a polycarbonate resin having high wear resistance, that is, a polycarbonate resin having a central carbon atom in the cyclohexylene group (polycarbonate Z (also simply referred to as BPZ)). Has been proposed (Patent Document 2).

  However, when the wear resistance of the organic photoreceptor is improved by using the binder, the wear resistance is improved. However, the surface of the photoreceptor is easily contaminated with paper dust or a toner composition. Periodic image defects such as small streak images) and transfer defects.

As described above, it is difficult to solve the above-described deterioration of the halftone image due to the dash mark or the scratch by the technique of improving the wear resistance of the organic photoreceptor using these binders. That is, when the wear characteristics are reinforced by using a binder resin that is difficult to scrape, the surface layer becomes resistant to scratches and wear, but contamination of the surface layer is likely to accumulate, and a dash mark is likely to occur. On the other hand, if the wear resistance is weak, scratches and wear on the surface layer increase, and there is a contradiction that halftone image quality is liable to deteriorate.
JP 2000-214629 A Japanese Patent Application Laid-Open No. 60-172044

  The present invention solves the conflicting properties of the organophotoreceptor with respect to foreign matter adhesion and abrasion resistance at the same time, and makes it difficult for foreign matter to adhere to the surface of the photoreceptor and to make it difficult to visualize scratches. The present invention provides an organic photoreceptor in which deterioration of a halftone image is prevented and generation of a dash mark, a transfer memory, and a spot is prevented, and an image forming apparatus and an image forming method using the organic photoreceptor are provided. That is.

In order to solve the above problems, the present inventors have studied the surface layer of the organic photoconductor to prevent dash marks and scratches, and at the same time, developed the technology that can prevent the generation of transfer memory and spots. By including the compound represented by the general formula (1) in the charge transport layer forming the surface layer of the body, it is possible to simultaneously improve the deterioration of the halftone image due to these dashes and scratches and the generation of transfer memory and spots. The present invention has been completed. That is, when the charge transporting layer of the surface layer contains the compound represented by the general formula (1), deterioration of the charge transporting layer binder resin, especially polycarbonate binder resin, due to oxidation is prevented, and the surface is hardly contaminated. Further, the present invention has been completed by finding that a surface layer which is difficult to be scratched is formed, halftone images are prevented from being deteriorated due to dash marks and scratches, and transfer memory and spots are prevented from being generated. That is, the object of the present invention can be achieved by having the following configuration.
(Claim 1)
An organophotoreceptor comprising a compound represented by the following general formula (1):

(In the formula, R ₁ represents an alkyl group having 2 to 5 carbon atoms.)
(Claim 2)
An organic photoreceptor having at least a photosensitive layer on a conductive support, wherein the surface layer contains a compound represented by the general formula (1).
(Claim 3)
3. The organic photoreceptor according to claim 2, wherein the photosensitive layer has a laminated structure of a charge generation layer and a charge transport layer, and the surface layer is a charge transport layer.
(Claim 4)
The organophotoreceptor according to claim 3, wherein the charge transport layer contains polycarbonate.
(Claim 5)
The organic photoreceptor according to claim 3 or 4, wherein the charge generation layer contains a gallium phthalocyanine pigment.
(Claim 6)
The organophotoreceptor according to claim 3 or 4, wherein the charge generation layer contains a titanyl phthalocyanine pigment.
(Claim 7)
The organic photoconductor according to claim 3, wherein the organic photoconductor has an intermediate layer containing N-type semiconductive particles between the conductive support and the charge generation layer. body.
(Claim 8)
The organophotoreceptor according to claim 7, wherein the N-type semiconductor particles are a metal oxide.
(Claim 9)
The organophotoreceptor according to claim 8, wherein the N-type semiconductor particles are titanium oxide or zinc oxide.
(Claim 10)
The organophotoreceptor according to claim 9, wherein the N-type semiconductor particles are titanium oxide.
(Claim 11)
The organophotoreceptor according to claim 10, wherein the titanium oxide is anatase titanium oxide or rutile titanium oxide.
(Claim 12)
The organophotoreceptor according to claim 7, wherein the N-type semiconductor particles are subjected to a surface treatment.
(Claim 13)
The organic photoreceptor according to claim 7, wherein the intermediate layer contains a binder of polyamide resin.
(Claim 14)
The organophotoreceptor according to claim 13, 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.
(Claim 15)
In an image forming apparatus having an organic photoreceptor and a charging means for forming an electrostatic latent image on the organic photoreceptor, an exposure means, and a developing means for developing the electrostatic latent image into a toner image. The organic photoreceptor contains the compound represented by the general formula (1).
(Claim 16)
An image forming method comprising forming an electrophotographic image using at least the image forming apparatus according to claim 15.

  By using the present invention, it is possible to simultaneously improve the deterioration of halftone images due to dash marks and scratches and the generation of transfer memory and spots, and to produce good electrophotographic images, and images using the organic photoreceptors A forming apparatus and an image forming method can be provided.

  Hereinafter, the present invention will be described in detail.

  The organophotoreceptor of the present invention contains the compound represented by the general formula (1).

  The organic photoreceptor of the present invention is characterized in that, in the organic photoreceptor having at least a photosensitive layer on a conductive support, the surface layer contains the compound represented by the general formula (1).

  The organophotoreceptor of the present invention has the above-described configuration, thereby preventing deterioration of halftone images due to dash marks and scratches, preventing generation of transfer memory and spots, and producing good electrophotographic images in the long term. it can.

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

  The compound represented by the general formula (1) contained in the surface layer of the organophotoreceptor of the present invention has good compatibility with a polycarbonate widely used as a binder for the organophotoreceptor and is deteriorated by oxidation of the polycarbonate. , Prevents deterioration of halftone images due to dash marks and scratches that are likely to occur on the surface layer, prevents generation of transfer memory and spots, and makes it possible to produce good electrophotographic images over the long term.

The compound of the general formula (1) is a compound within the scope of the present invention in which R ₁ is an alkyl group having 2 to 5 carbon atoms. When R ₁ is ₁ carbon atom, the softening point effect of a resin such as polycarbonate is obtained. As a result, the surface layer becomes soft, and the wear resistance characteristics tend to deteriorate. Further, the adhesion of foreign matter is increased, and a dash mark or the like is likely to occur. On the other hand, when R ₁ has 6 or more carbon atoms, the compatibility with polycarbonate deteriorates and the improvement effect is small.

  The compound of the general formula (1) of the present invention has a great effect of preventing deterioration of the halftone image due to the dash marks and scratches and preventing the generation of transfer memory and spots, when used in combination with polycarbonate. The above-mentioned improvement effect is large by using together with the polycarbonate which has a structural unit represented by the following.

Hereinafter, polycarbonates preferably used in the present invention are exemplified, but the present invention is not limited to polycarbonates having these exemplified structures.

  The polycarbonate resin used in the present invention can be obtained by a general polycarbonate synthesis method such as a phosgene method using a diol compound having each structural unit.

  The molecular weight of the polycarbonate of the present invention is preferably a viscosity average molecular weight (Mv) in the range of 10,000 to 150,000, particularly 15 in consideration of the dash mark resistance and abrasion resistance. , Preferably in the range of 100,000 to 100,000.

  Next, a configuration in which the surface layer of the photosensitive layer is a charge transport layer and the compound of the general formula (1) is used for the charge transport layer will be described.

  When the compound of the general formula (1) is contained in the charge transport layer, the content in the charge transport layer is preferably 0.01 to 20% by mass. If the content is less than 0.01% by mass, transfer memory tends to occur. If the content is more than 20% by mass, the charge transport ability in the surface layer decreases, the residual potential tends to increase, and the film strength decreases. Muscle damage is likely to occur.

  Moreover, when using polycarbonate resin as a binder resin for a charge transport layer, the ratio of the binder resin in the charge transport layer is 20 to 80% by mass, preferably 30 to 60% by mass. In the charge transport layer, in addition to the above polycarbonate copolymer, 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 A resin, a silicone resin, a melamine resin, and a copolymer resin containing two or more of the repeating unit structures of these resins may be used in combination.

  In the charge transport layer, a compound represented by the following general formula (2), general formula (3), or general formula (4) is preferably used as a charge transport material as a carrier transport material.

(In the general formula (2), R ₁ and R ₁ ′ each represent a hydrogen atom, an alkyl group, an alkoxy group or a halogen atom, and R ₂ , R ₂ ′, R ₃ and R ₃ ′ each represent a hydrogen atom, Represents an alkyl group, an alkoxy group, a halogen atom or a substituted amino group, and m, m ′, n and n ′ each represent an integer of 1 or 2.)

(In the general formula (3), R ₄ represents a hydrogen atom or a methyl group, and Ar ₁ and Ar ₂ are each an aryl group optionally having a halogen atom, an alkyl group, an alkoxy group or a substituted amino group, or Represents a thienyl group, and k represents an integer of 1 or 2.)

[In the general formula (4), Ar ₅ , Ar ₆ and Ar ₇ represent a substituted or unsubstituted aromatic hydrocarbon or heterocyclic group, and R ₃ represents a hydrogen atom or a substituted or unsubstituted aromatic hydrocarbon. Represents a group or a heterocyclic group. n is 2 or 3. ]
The charge transport materials of the general formula (2), general formula (3), and general formula (4) have good compatibility with the polycarbonate. By using these charge transport materials and the polycarbonate together, a micro phase can be obtained. Forms a uniform and non-separable charge transport layer that prevents adhesion of foreign matter, prevents the occurrence of dashes and scratches, prevents deterioration of halftone images, and has stable potential characteristics that do not easily cause transfer memory. it can.

  Specific examples of the compounds represented by the general formula (2), the general formula (3), and the general formula (4) are given below, but the present invention is not limited to the specific examples.

  Specific example of general formula (2)

  Specific example of general formula (3)

  Specific example of general formula (4)

  The mass ratio of the binder resin using the polycarbonate in the charge transport layer and the charge transport material is preferably 30 to 200 parts by mass, more preferably 50 to 150 parts by mass with respect to 100 parts by mass of the binder.

  The thickness of the charge transport layer is preferably 10 to 40 μm. If the film thickness is less than 10 μm, deterioration of the halftone image tends to appear, and if it exceeds 40 μm, the residual power rises easily and sharpness tends to deteriorate.

  Further, the charge transport layer may be composed of two layers, and the polycarbonate of the present invention may be used for the charge transport layer serving as the surface layer.

  Next, the layer structure of the organic photoreceptor having the above surface layer will be described.

  The organic photoconductor of the present invention means an electrophotographic photoconductor constituted by giving an organic compound at least one of a charge generation function and a charge transport function indispensable for the constitution of the electrophotographic photoconductor. It contains all known organic electrophotographic photoreceptors such as a photoreceptor composed of an organic charge generating material or an organic charge transport material, a photoreceptor composed of a polymer complex with a charge generating function and a charge transport function.

  The constitution of the organic photoreceptor used in the present invention is described below.

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.

  Here, a method for discriminating N-type semiconductor particles will be described.

  An intermediate layer having a thickness of 5 μm is formed on the conductive support (the intermediate layer is formed using a dispersion in which 50% by mass of particles are dispersed in the binder resin constituting the intermediate layer). The intermediate layer is negatively charged and the light attenuation characteristics are evaluated. In addition, the light attenuation characteristics are similarly evaluated by charging to positive polarity.

  N-type semiconductive particles are particles that are dispersed in the intermediate layer in the above evaluation when the light attenuation when charged negatively is greater than the light attenuation when charged positively. It is called semiconductive particle.

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

  The N-type semiconductor particles are preferably fine particles having a number average primary particle size in the range of 3.0 to 200 nm. Particularly, 5 nm to 100 nm is preferable. The number average primary particle diameter is a measured value as the average diameter in the ferret direction by image analysis by magnifying fine particles 10,000 times by transmission electron microscope observation, randomly observing 100 particles as primary particles. 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 agglomerated particles. Likely to happen. On the other hand, N-type semiconducting particles having a number average primary particle size of greater than 200 nm tend to make large irregularities on the surface of the intermediate layer, and halftone images are likely to deteriorate through these large irregularities. Further, N-type semiconducting particles having a number average primary particle size of more than 200 nm are likely to precipitate in the dispersion and easily generate agglomerates, which also increases the deterioration of the halftone image.

  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. That is, the electron mobility is increased, the charging potential is stabilized, the residual potential is prevented from increasing, and the generation of the transfer memory can be prevented. .

  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 in producing a good halftone image.

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 N-type semiconductive particles may be those that have been surface-treated with a reactive organosilicon compound represented by the following general formula (5).

General formula (5)
(R) _n -Si- (X) _4-n
(In the formula, Si represents a silicon atom, R represents an organic group in which carbon is directly bonded to the silicon atom, X represents a hydrolyzable group, and n represents an integer of 0 to 3.)
In the organosilicon compound represented by the general formula (5), an organic group in which carbon is directly bonded to silicon represented by R includes alkyl such as methyl, ethyl, propyl, butyl, pentyl, hexyl, octyl, and dodecyl. Group, aryl group such as phenyl, tolyl, naphthyl, biphenyl, epoxy-containing group such as γ-glycidoxypropyl, β- (3,4-epoxycyclohexyl) ethyl, γ-acryloxypropyl, γ-methacryloxypropyl (Meth) acryloyl group, hydroxyl group such as γ-hydroxypropyl and 2,3-dihydroxypropyloxypropyl, vinyl group such as vinyl and propenyl, mercapto group such as γ-mercaptopropyl, γ-aminopropyl, Amino-containing groups such as N-β (aminoethyl) -γ-aminopropyl, γ-chloropropyl, , 1,1-tri fluoroalkyl propyl, nonafluorohexyl, halogen-containing groups such as perfluorooctylethyl, other nitro, and cyano-substituted alkyl group. Examples of the hydrolyzable group for X include alkoxy groups such as methoxy and ethoxy, halogen groups, and acyloxy groups.

  Moreover, the organosilicon compound represented by General formula (5) may be individual, and may be used in combination of 2 or more type.

  Moreover, in the specific compound of the organosilicon compound represented by the general formula (5), when n is 2 or more, a plurality of R may be the same or different. Similarly, when n is 2 or less, the plurality of Xs may be the same or different. Moreover, when using 2 or more types of organosilicon compounds represented by General formula (5), R and X may be the same between each compound, and may differ.

  Further, prior to the surface treatment of the methylhydrogensiloxane copolymer or the reactive organosilicon compound, the N-type semiconductive particles may be subjected to an inorganic surface treatment such as alumina or silica.

  In addition, although the above-mentioned treatment of alumina and silica may be performed simultaneously, it is preferable to perform the alumina treatment first and then the silica treatment. Further, the amount of treatment of alumina and silica when treating alumina and silica is preferably higher than that of alumina.

  The surface treatment of the N-type semiconductive fine particles such as titanium oxide with a metal oxide such as alumina, silica or zirconia can be performed by a wet method. For example, N-type semiconductive particles subjected to silica or alumina surface treatment can be prepared as follows.

  When titanium oxide particles are used as the N-type semiconductive particles, titanium oxide particles (number average primary particle size: 50 nm) are dispersed in water at a concentration of 50 to 350 g / L to form an aqueous slurry. Add acid salt or water-soluble aluminum compound. Thereafter, alkali or acid is added for neutralization, and silica or alumina is precipitated on the surface of the titanium oxide particles. Subsequently, filtration, washing, and drying are performed to obtain the target surface-treated titanium oxide. 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.

  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 0.5 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 rectifying property of the intermediate layer is increased, and no increase in residual potential or transfer memory occurs even when the film thickness is increased. Therefore, it is possible to form an organic photoreceptor capable of effectively preventing black spots and producing a good halftone image with small potential fluctuation. Further, such an intermediate layer preferably uses 50 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.

  That 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 is preferable for the intermediate layer. The heat of fusion is more preferably 0 to 30 J / g, and most preferably 0 to 20 J / g. On the other hand, when the water absorption exceeds 5% by mass, the moisture content in the intermediate layer increases, the rectification property of the intermediate layer decreases, black spots tend to occur, and the halftone image tends to deteriorate. The water absorption is more preferably 4% by mass or less.

  The heat of fusion of the resin is measured by DSC (Differential Scanning Calorimetry). However, if the same measurement value as the DSC measurement value is obtained, the DSC measurement method is not particular. The heat of fusion is determined from the endothermic peak area when the DSC temperature rises.

  On the other hand, the water absorption rate of the resin is determined by mass change by the water immersion method or by the Karl Fischer method.

  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. This resin has a high water absorption rate, and the intermediate layer using such a polyamide tends to be highly environment-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. Black spots are likely to occur and halftone images are likely to deteriorate.

  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 (6), 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 (7), 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 (6), 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 (7), 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%.

  When the carbon number is less than 7, the hygroscopicity of the polyamide resin is large, the electrophotographic characteristics, particularly the humidity dependency of the potential during repeated use is large, and image defects such as black spots are likely to occur, and the halftone image is 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 (8).

In General Formula (8), 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 (8), 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 shows an improvement effect of preventing deterioration of a halftone image due to black spots or scratches.

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 (8) 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 tends to be lowered, and an agglomerated resin is likely to be generated in the intermediate layer, so that black spots and halftone images are likely to be deteriorated.

  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.

Synthesis of exemplified polyamide resin (N-1) 215 parts by mass of lauryl lactam, 3-aminomethyl-3,5,5-trimethylcyclohexylamine in a polymerization kettle equipped with a stirrer, nitrogen, nitrogen introduction tube, thermometer, dehydration tube, etc. 112 parts by mass, 153 parts by mass of 1,12-dodecanedicarboxylic acid and 2 parts by mass of water were mixed and reacted for 9 hours while distilling water under heating and pressure. When the polymer was taken out and the copolymer composition was determined by C ¹³ -NMR, it coincided with the composition of N-1. The melt flow index (MFI) of the synthesized copolymer was 5 g / 10 min under the condition of (230 ° C./2.16 kg).

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 film thickness of the intermediate layer is less than 0.5 μm, black spots and halftone images are likely to deteriorate. If the film thickness exceeds 10 μm, residual potential increases and transfer memory tends to occur, and sharpness 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. In the positively charged photoconductor, the order of the layer configuration is the reverse of that in the negatively charged photoconductor. The most preferred photosensitive layer structure of the present invention is a negatively charged photoreceptor structure having the function separation structure.

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

Charge generation layer The charge generation layer contains a charge generation material (CGM). Other substances may contain a binder resin and other additives as necessary.

  A known charge generation material (CGM) can be used as the charge generation material (CGM). For example, a phthalocyanine pigment, an azo pigment, a perylene pigment, an azulenium pigment, or the like can be used. The CGM preferably used in the present invention has a crystal structure capable of forming a stable aggregate structure among a plurality of molecules. Specific examples include CGMs of phthalocyanine pigments and perylene pigments having a specific crystal structure. For example, titanyl phthalocyanine having a maximum peak at a Bragg angle 2θ of 27.2 ° with respect to Cu—Kα rays, titanyl phthalocyanine having a remarkable diffraction peak at 7.5 ° and 28.7 ° of the same 2θ, and 12.2 of the same 2θ. CGM such as bisbenzimidazole perylene having a maximum peak at 4 is hardly deteriorated by repeated use, and the residual potential can be increased and decreased.

  Further, it is characteristic at positions of at least 7.4 °, 16.6 °, 25.5 ° and 28.3 ° in the Bragg angle (2θ ± 0.2 °) of the characteristic X-ray diffraction spectrum of Cu-Kα. Chlorgallium phthalocyanine pigment with diffraction peaks, characteristic at positions of at least 7.5 °, 9.9 °, 12.5 °, 16.3 °, 18.6 °, 25.1 °, 28.1 ° Preference is given to hydroxygallium phthalocyanine pigments having diffraction peaks and gallium phthalocyanine pigments having characteristic diffraction peaks at positions of at least 6.8 °, 12.8 °, 15.8 °, 26.6 °.

  In particular, when a phthalocyanine pigment is used in the charge generation layer, the inclusion of the compound of the general formula (1) of the present invention in the charge transport layer adjacent to the charge generation layer improves the memory phenomenon that is likely to occur with the phthalocyanine pigment, It can be made smaller.

  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 0.01 μm to 1 μm. If the thickness is less than 0.01 μm, sufficient sensitivity characteristics cannot be obtained, and the residual potential tends to increase. On the other hand, even if the thickness exceeds 1 μm, the sensitivity tends to decrease and a transfer memory tends to occur.

Charge Transport Layer The charge transport layer of the present invention is used as the charge transport layer of the present invention.

  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.

  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 manufacturing the organic photoreceptor, a coating processing method such as dip coating, spray coating, circular amount regulation type coating or the like is used. It is most preferable to use the circular amount regulation type coating method for the protective layer. The circular amount regulation type coating is described in detail in, for example, Japanese Patent Application Laid-Open No. 58-189061.

  Next, an image forming apparatus using the organic photoreceptor of 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 color, developing means (development process) 23, transfer / conveying belt device 45 as transfer means (transfer process), cleaning device (cleaning process) 26 for the photosensitive member 21, and photostatic means (photo-site charge). PCLs (precharge lamps) 27 as generating steps) are arranged in the order of operation. Further, on the downstream side of the developing means 23, a reflection density detecting means 222 for measuring the reflection density of the patch image developed on the photoreceptor 21 is provided. The photoconductor 21 uses the organic photoconductor of the present invention and is driven to rotate in the clockwise direction shown in the figure.

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

In the image forming method of the present invention, when an electrostatic latent image is formed on a photoreceptor, it is preferable to perform image exposure using an exposure beam having a spot area of 2 × 10 ⁻⁹ m ² or less. Even when such small-diameter beam exposure is performed, the organic photoreceptor of the present invention can faithfully form an image corresponding to the spot area. A more preferable spot area is 0.01 × 10 ⁻⁹ to 1 × 10 ⁻⁹ m ² . As a result, it is possible to achieve extremely excellent image quality that achieves 256 gradations at 400 dpi (dpi: the number of dots per 2.54 cm) or more.

The spot area of the exposure beam is represented by an area corresponding to a light intensity at which the intensity of the beam light is 1 / e ² or more of the peak intensity.

The exposure beam used includes a scanning optical system using a semiconductor laser, and a solid state scanner such as an LED or a liquid crystal shutter. The light intensity distribution includes a Gaussian distribution and a Lorentz distribution, but 1 / e of each peak intensity. ^The area up to ² is the spot area.

  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, either a pulverized toner or a polymerized toner may be used as the developer used in the developing means. However, a polymerized toner having a uniform shape and particle size distribution is used as the organic photoreceptor of the present invention. By using in combination, an electrophotographic image with better sharpness can be obtained.

  The organic photoreceptor of the present invention is effective when the toner containing 0.1 to 1.0 μm of inorganic external additive and 50 nm or less of inorganic external additive is used as a developer. Greatly prevents deterioration of halftone images due to scratches and improves transfer memory.

  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.

  Next, FIG. 2 shows a color image forming apparatus using the organic photoreceptor of the present invention (a copying machine having at least a charging means, an exposing means, a plurality of developing means, a transfer means, a cleaning means, and an intermediate transfer body around the organic photoreceptor. 1 is a sectional view of the configuration of a laser beam printer). The belt-shaped intermediate transfer body 70 uses an elastic body having a medium resistance.

  Reference numeral 21 denotes a rotary drum type photoconductor that is repeatedly used as an image forming body, and is rotated at a predetermined peripheral speed in the counterclockwise direction indicated by an arrow.

  In the rotation process, the photosensitive member 21 is uniformly charged to a predetermined polarity and potential by the charging unit 22, and then modulated by the image exposure unit 30 (not shown) corresponding to the time-series electric digital pixel signal of the image information. An electrostatic latent image corresponding to a yellow (Y) color component image of a target color image is formed by receiving image exposure with scanning exposure light or the like by a laser beam.

  Next, the electrostatic latent image is developed with yellow toner which is the first color by yellow (Y) developing means (yellow color developing device) 23Y. At this time, the second to fourth developing means (magenta developer, cyan developer, black developer) 23M, 23C, and 23Bk are turned off and do not act on the photosensitive member 21. 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 rotationally driven in the clockwise direction at the same peripheral speed as the photosensitive member 21.

  The yellow toner image of the first color formed and supported on the photoreceptor 21 is applied to the intermediate transfer body 70 from the primary transfer roller 24a 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 photoconductor 21 after the transfer of the first color yellow toner image corresponding to the intermediate transfer body 70 is cleaned by the cleaning device 26.

  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 24b 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 21 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 21 to the intermediate transfer member 70, the secondary transfer roller 24b and the intermediate transfer member cleaning means 26A can be separated from the intermediate transfer member 70. is there.

  When the superimposed color toner image transferred onto the belt-shaped intermediate transfer body 70 is transferred to the transfer material P, which is the second image carrier, the secondary transfer roller 24b is brought into contact with the belt of the intermediate transfer body 70. At the same time, the transfer material P is fed from the pair of paper supply registration rollers 44 through the transfer sheet guide to the belt of the intermediate transfer body 70 to the contact nip with the secondary transfer roller 24b at a predetermined timing. A secondary transfer bias is applied to the secondary transfer roller 24b 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 50 and fixed by heating.

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

  FIG. 3 is a cross-sectional configuration diagram of another color image forming apparatus using the organic photoreceptor 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 41 and a fixing means 50. A document image reading device SC is disposed on the upper part of the main body A of the image forming apparatus.

  An image forming unit 10Y that forms a yellow image includes a charging unit 22Y, an exposure unit 30Y, a developing unit 23Y, and a primary transfer unit disposed around a drum-shaped photoconductor 21Y as a first image carrier. A primary transfer roller 5Y and a cleaning means 6Y are provided. The image forming unit 10M that forms a magenta image includes a drum-shaped photosensitive member 21M as a first image carrier, a charging unit 22M, an exposure unit 30M, a developing unit 23M, 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 photosensitive member 21C as a first image carrier, a charging unit 22C, an exposure unit 30C, a developing unit 23C, 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 21Bk as a first image carrier, a charging unit 22Bk, an exposure unit 30Bk, a developing unit 23Bk, 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 22Y, 22M, 22C, and 22Bk that rotate around the photosensitive drums 21Y, 21M, 21C, and 21Bk, and image exposure means 30Y, 30M, 30C and 30Bk, rotating developing means 23Y, 23M, 23C and 23Bk, and cleaning means 5Y, 5M, 5C and 5Bk for cleaning the photosensitive drums 21Y, 21M, 21C and 21Bk.

  The image forming units 10Y, 10M, 10C, and 10Bk have the same configuration except that the colors of the toner images formed on the photoreceptors 21Y, 21M, 21C, and 21Bk are different, and the image forming unit 10Y is taken as an example in detail. explain.

  The image forming unit 10Y includes a charging unit 22Y (hereinafter simply referred to as a charging unit 22Y or a charger 22Y), an exposure unit 30Y, a developing unit 23Y, and a cleaning unit 5Y (around a photosensitive drum 21Y as an image forming body). Hereinafter, the cleaning unit 5Y or the cleaning blade 5Y) is simply disposed, and a yellow (Y) toner image is formed on the photosensitive drum 21Y. In the present embodiment, in the image forming unit 10Y, at least the photosensitive drum 21Y, the charging unit 22Y, the developing unit 23Y, and the cleaning unit 5Y are provided so as to be integrated.

  The charging unit 22Y is a unit that applies a uniform potential to the photosensitive drum 21Y. In the present embodiment, a corona discharge type charger 22Y is used for the photosensitive drum 21Y.

  The image exposure unit 30Y performs exposure based on the image signal (yellow) on the photosensitive drum 21Y given a uniform potential by the charger 22Y, and forms an electrostatic latent image corresponding to the yellow image. As the exposure means 30Y, the exposure means 30Y includes an LED in which light emitting elements are arranged in an array in the axial direction of the photosensitive drum 21Y and an imaging element (trade name; Selfoc lens), or A laser optical system or the like is used.

  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 sheet P as a recording material (a support for carrying a fixed final image: for example, plain paper, transparent sheet, etc.) housed in the sheet feed cassette 40 is fed by a sheet feeding means 41, and has a plurality of intermediate rollers. After passing through 42A, 42B, 42C, 42D and the registration roller 43, it is conveyed to the secondary transfer roller 5A as the secondary transfer means, and is secondarily transferred onto the paper P and the color images are collectively transferred. The paper P on which the color image has been transferred is fixed by the fixing unit 50, is sandwiched between the paper discharge rollers 45, and is placed on a paper discharge tray 46 outside the apparatus.

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

  During the image forming process, the primary transfer roller 5Bk is always in pressure contact with the photoreceptor 21Bk. The other primary transfer rollers 5Y, 5M, and 5C are in pressure contact with the corresponding photoreceptors 21Y, 21M, and 21C, respectively, only during color image formation.

  The secondary transfer roller 5A comes into pressure contact with the endless belt-shaped intermediate transfer body 70 only when the sheet P passes through the secondary transfer roller 5A and secondary transfer is performed.

  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 arranged on the left side of the photoreceptors 21Y, 21M, 21C, and 21Bk 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 6A. Consists of.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, the aspect of this invention is not limited to this. However, “part” in the following text indicates “part by mass”.

  A photoreceptor used for evaluation was produced as follows.

Preparation of photoreceptor 1 Intermediate layer The following intermediate layer coating solution is applied by a dip coating method onto a cleaned cylindrical aluminum substrate (10-point surface roughness Rz defined by JISB-0601 by cutting): 0.81 μm) And dried at 120 ° C. for 30 minutes to form an intermediate layer having a dry film thickness of 3.0 μm.

  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 (1.00 volume part)
2. Rutile-type titanium oxide A1 (primary particle size 35 nm; a surface treatment using a copolymer of methylhydrogensiloxane and dimethylsiloxane (molar ratio 1: 1) in an amount of 5% by mass of the total mass of titanium oxide) 5 parts (1.0 part by volume)
Ethanol / n-propyl alcohol / THF (= 45/20/30 mass ratio) 10 parts The above components were mixed and dispersed in a batch system for 10 hours using a sand mill disperser to prepare an intermediate layer dispersion. .

Charge generation layer The following components were mixed and dispersed using a sand mill disperser 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 0.3 μm on the intermediate layer.

Charge generation material: hydroxygallium phthalocyanine pigment (at least 7.5 °, 9.9 °, 12.5 °, 16.3 at the Bragg angle (2θ ± 0.2 °) of the characteristic X-ray diffraction spectrum of Cu-Kα) (Hydroxygallium phthalocyanine pigment having diffraction peaks characteristic at positions of 18.6 °, 25.1 °, and 28.1 °) 20 parts Silicone-modified polyvinyl butyral 10 parts 4-methoxy-4-methyl-2-pentanone 700 Part t-Butyl acetate 300 parts Charge transport layer The following components were mixed and dissolved to prepare a charge transport layer coating solution. This coating solution was applied onto the charge generation layer by a dip coating method to form a charge transport layer having a dry film thickness of 25 μm.

Charge transport material (Exemplary compound CT1-27) 70 parts Binder resin (Exemplary compound PC-1 (Mv: 30000)) 100 parts Compound of general formula (1) wherein R ₁ is ethyl group 8 parts Tetrahydrofuran / toluene (volume ratio 8 / 2) 750 parts Preparation of photoconductors 2 to 15 N-type semiconductive particles of the intermediate layer, binder resin, dry film thickness, charge generation material, binder resin of charge transport layer, charge transport material, of the general formula (1) Photoconductors 2 to 15 were produced in the same manner as the photoconductor 1 except that the compounds, film thickness, and the like were changed as shown in Table 1. However, the volume ratio of the intermediate layer in Table 1 is the same as the volume of the binder resin and the volume of the binder resin after the total volume of the binder resin in all the intermediate layers of the photoreceptors 1 to 15 and the volume of the N-type semiconductor particles are made constant. An intermediate layer dispersion was prepared by changing the volume ratio (Vn / Vb) of the type semiconductive particles to form an intermediate layer.

At the same time as the production of the photoconductors 1 to 15, each intermediate layer coating solution was applied onto an aluminum-deposited polyethylene terephthalate support using the intermediate layer coating solution of each photoconductor. An intermediate layer having a dry film thickness of 10 μm was formed under the same conditions to prepare a volume resistance measurement sample, and the volume resistance of each intermediate layer was measured. As a result, the volume resistances of the intermediate layers of the photoreceptors 1 to 15 were all 1 × 10 ⁸ Ω · cm or more.

In the table,
A1 is rutile titanium oxide A2 is anatase titanium oxide Z is zinc oxide * 1 is a copolymer of methylhydrogensiloxane and dimethylsiloxane (molar ratio 1: 1)
* 2 is a copolymer of methylhydrogensiloxane and dimethylsiloxane (molar ratio 9: 1)
* 3 is a copolymer of methylhydrogensiloxane and dimethylsiloxane (molar ratio 2: 8)
* 4 is a copolymer of methylhydrogensiloxane and diethylsiloxane (molar ratio 1: 1)
* 5: Copolymer of methylhydrogensiloxane and methylethylsiloxane (molar ratio 1: 1)
* 6 is methylhydrogenpolysiloxane * 7 is primary treatment: silica / alumina, secondary treatment methyltrimethoxysilane In the table, surface treatment refers to the substance used for the surface treatment applied to the surface of the particles (however, The silica / alumina of the primary treatment means silica / alumina deposited on the particle surface).

  The heat of fusion and water absorption in the table were measured as follows.

Measurement conditions of heat of fusion Measuring machine: Measured using Shimadzu Corporation “Shimadzu heat flow rate differential scanning calorimeter DSC-50”.

  Measurement conditions: The measurement sample is set in the above-mentioned measuring machine, measurement is started from room temperature (24 ° C.), the temperature is raised to 200 ° C. at 5 ° C./min, and then cooled to room temperature at 5 ° C./min. This is repeated twice, and the heat of fusion is calculated from the endothermic peak area due to melting during the second temperature increase.

Measurement condition of water absorption rate The sample to be measured is sufficiently dried at 70 to 80 ° C. for 3 to 4 hours, and its mass is accurately weighed. Next, the sample is put into ion-exchanged water maintained at 20 ° C., and after a certain period of time, the sample surface is pulled up and wiped off with a clean cloth, and the mass is measured. The above operation was repeated until the increase in mass was saturated, and the value obtained by dividing the increased mass (increase) of the resulting sample by the initial mass was taken as the water absorption rate.

  In the table, the ratio of the unit structure having 7 or more carbon atoms refers to the ratio (mol%) of the repeating unit structure having 7 or more carbon atoms between amide bonds in the repeating unit structure.

  In the table, G1, G2, G3 and Y represent the following charge generating substances.

G1 is at least 7.5 °, 9.9 °, 12.5 °, 16.3 °, 18.6 ° in the Bragg angle (2θ ± 0.2 °) of the characteristic X-ray diffraction spectrum of Cu—Kα, Hydroxygallium phthalocyanine pigment G2 having characteristic diffraction peaks at positions of 25.1 ° and 28.1 ° G2 is at least 7. in the Bragg angle (2θ ± 0.2 °) of the characteristic X-ray diffraction spectrum of Cu-Kα. Chlorgallium phthalocyanine pigment having characteristic diffraction peaks at positions of 4 °, 16.6 °, 25.5 °, 28.3 ° G3 is a Bragg angle (2θ ± 0. 0.) of the characteristic X-ray diffraction spectrum of Cu-Kα. 2), a gallium phthalocyanine pigment having characteristic diffraction peaks at positions of at least 6.8 °, 12.8 °, 15.8 °, and 26.6 ° Y is X-ray diffraction by Cu-Kα characteristic X-ray In the spectrum In Y type titanyl phthaloyl thin pigment Table 1 having a maximum diffraction peak at a Bragg angle (2θ ± 0.2 °) 27.3 °,
* 1 uses mixed charge transport materials (CT1-27 / CT2-28 is used at a mass ratio of 6/2)
* 2: Mixing charge transport materials (CT1-28 / CT2-28 used at a mass ratio of 6/2)
<Evaluation>
The obtained photoreceptor was mounted on a commercially available color printer, magiccolor 2300 Desk Laser (manufactured by Minolta EMS), and an endurance test was conducted at low temperature and low humidity (LL: 10 ° C., 20% RH). Specifically, a total of 20,000 image images in which the character ratio, halftone image, solid white image, and solid black image with a pixel rate of 7% are divided into quarters are printed, and evaluated at the start and every 5000 images. did. Evaluation items and evaluation criteria are shown below.

  The process conditions for the color printer were as follows.

Charger: Sawtooth electrode Exposure device: Semiconductor laser Development: Nonmagnetic polymerized toner having an average particle diameter of 6.5 μm and containing 0.3 μm of strontium titanate and 15 nm of hydrophobic silica, reversal development method Transfer: Use of intermediate transfer belt Cleaning: Cleaning blade Fixing: Heat fixing Process speed: 100mm / sec
Image density Measured using a Macbeth RD-918. The relative reflection density was measured with the paper reflection density set to “0”. As the residual potential increases on multiple copies, the image density decreases.

A: Black solid image is higher than 1.2 (good)
○: Black solid image is 1.0 or more and 1.2 or less (no problem in practical use)
×: Black solid image is less than 1.0 (practical problem)
The fog density was measured by reflection density of a solid white image using RD-918 manufactured by Macbeth. The reflection density was evaluated by a relative density (the density of A4 paper not printed is 0.000).

A: Concentration is less than 0.010 (good)
○: Concentration of 0.010 or more and 0.020 or less (a level causing no practical problem)
X: Concentration is higher than 0.020 (a level that causes practical problems)
Dash Mark The state of occurrence of a dash mark (small comet-like streak image) whose periodicity coincides with the period of the photoreceptor on the halftone image was determined according to the following criteria.

A: Frequency of dash marks of 0.4 mm or more: All printed images are 5 / A4 or less (good)
O: Frequency of dash marks of 0.4 mm or more: 1 or more of 6 / A4 or more and 10 / A4 or less (no problem in practical use)
X: Frequency of dash mark image defects of 0.4 mm or more: 11 or more A4 or more occurred (practical problem)
Black spots The periodicity coincided with the period of the photoconductor, and it was determined how many black spots and black streak-like image defects that can be seen per A4 size.

A: Frequency of image defects of 0.4 mm or more: All printed images are 5 / A4 or less (good)
○: Frequency of image defects of 0.4 mm or more: 1 or more of 6 / A4 or more and 10 / A4 or less (no problem in practical use)
X: Frequency of image defects of 0.4 mm or more: 11 or more A4 or more occurred (practical problem)
Halftone image sharpness (scratches)
A: The surface of the photoconductor is uniformly cut, and the halftone image is reproduced as a uniform and clean image (good).
○: A small scratch is generated on the surface of the photoreceptor, but the halftone image is reproduced as a uniform and clean image (no problem in practical use)
X: Scratches are generated on the surface of the photoreceptor, and the halftone image is a rough image. (There are practical problems)
Transfer memory Judgment was made based on whether high-density characters appeared in the next halftone image (memory generated) or not (no memory generated).

○: No memory generated ×: Memory generated

From the results of Table 2, the organic photoreceptors (Nos. 1 to 13) having the surface layer containing the compound represented by the general formula (1) are prevented from generating dashes, black spots, or transfer memory. Further, the evaluation of the image density and the fog is good, and an electrophotographic image having a good halftone image sharpness is obtained. On the other hand, the photoreceptor 14 containing the compound of the general formula (1) in which R ₁ is methyl other than the present invention has a reduced image density, dash marks, and a sharp halftone image. _The photoconductor 15 containing the compound of the general formula (1) in which ₁ is hexyl causes a decrease in image density, fogging and black spots, a transfer memory, and a sharpness of a halftone image.

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

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 21 Photoconductor 22 Charging means 23 Developing means 24 Transfer pole 25 Separation pole 26 Cleaning device 30 Exposure optical system 45 Transfer conveyance belt apparatus 50 Fixing means 250 Separation claw unit

Claims (16)

An organophotoreceptor comprising a compound represented by the following general formula (1):

(In the formula, R ₁ represents an alkyl group having 2 to 5 carbon atoms.) An organic photoreceptor having at least a photosensitive layer on a conductive support, wherein the surface layer contains a compound represented by the general formula (1). 3. The organic photoreceptor according to claim 2, wherein the photosensitive layer has a laminated structure of a charge generation layer and a charge transport layer, and the surface layer is a charge transport layer. 4. The organophotoreceptor according to claim 3, wherein the charge transport layer contains polycarbonate. 5. The organic photoreceptor according to claim 3, wherein the charge generation layer contains a gallium phthalocyanine pigment. The organophotoreceptor according to claim 3, wherein the charge generation layer contains a titanyl phthalocyanine pigment. The organic photosensitive material according to claim 3, wherein the organic photosensitive material has an intermediate layer containing N-type semiconductive particles between the conductive support and the charge generation layer. body. The organophotoreceptor according to claim 7, wherein the N-type semiconductor particles are a metal oxide. The organophotoreceptor according to claim 8, wherein the N-type semiconductor particles are titanium oxide or zinc oxide. The organophotoreceptor according to claim 9, wherein the N-type semiconductor particles are titanium oxide. The organophotoreceptor according to claim 10, wherein the titanium oxide is anatase titanium oxide or rutile titanium oxide. The organophotoreceptor according to any one of claims 7 to 11, wherein the N-type semiconductor particles are subjected to a surface treatment. The organic photoreceptor according to claim 7, wherein the intermediate layer contains a binder of polyamide resin. The organophotoreceptor according to claim 13, 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. In an image forming apparatus comprising an organic photoreceptor, a charging means for forming an electrostatic latent image on the organic photoreceptor, an exposure means, and a developing means for developing the electrostatic latent image into a toner image. An image forming apparatus, wherein the organic photoreceptor contains a compound represented by the general formula (1). An image forming method comprising forming an electrophotographic image using at least the image forming apparatus according to claim 15.

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