JP2011227234A - Electrophotographic photoreceptor and image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce interference patterns in an electrophotographic photoreceptor having a laminated structure, and to provide an electrophotographic photoreceptor that causes no white spot defect and can realize high image quality for light printing industry and the like, and an image forming method using it.SOLUTION: An electrophotographic photoreceptor includes at least a charge generating layer and a charge transport layer layered in this order on a conductive support. The charge generating layer contains at least titanyl phthalocyanine and particles having a particle size d between 0.5 μm and 5.0 μm, and the relation between the particle size d and the film thickness Hd of the charge generating layer is 0.5<d/Hd<2.

Description

  The present invention relates to an electrophotographic photosensitive member and an image forming method using the same.

  In recent years, the image quality of an image forming system using a dry electrophotographic system has been improved, and the image forming system has been widely used in the printing field with a relatively small number of copies. As a result, the required image quality has further increased, and it has come to be frequently used for rarely used methods such as printing on coated paper, printing of high coverage images, mass printing of high-quality images, etc. . As a result, the occurrence of problems that have not been pointed out in the past has increased.

  One of them is the generation of an interference fringe pattern of a halftone image which is considered to be caused by interference between the incident light for writing and the inner surface reflected light of the layers constituting the electrophotographic photosensitive member. This is a problem that has become apparent in recent years due to the demands for improving the uniformity of intermediate colors, the performance of the image forming apparatus, and the trend of users and technologies such as the use of coated paper, and the conventional technology cannot cope with it.

  The above problem is caused by the exposure of a single wavelength light such as a laser and the state of the boundary surface of the layers constituting the photoreceptor. The present invention is intended to prevent the interference fringe failure by forming irregularities on the surface of the charge generation layer, but such an attempt is not completely absent.

  However, there is not much recognition that interference fringe failure, which has been widely taken up in recent years, depends on the surface state of the charge generation layer (Patent Document 1), and a technique for forming irregularities on the surface of the charge generation layer has been studied. However, the purpose is not to deal with interference fringe failure but to solve a completely different problem (Patent Document 2). In addition, if particulate foreign matter is added to the charge generation layer, there is a risk of white spot failure occurring on the formed image. In this sense, it is not considered a promising technique in practice, and detailed studies have not been conducted. It was. Therefore, it is not clear how the charge generation layer suitable for preventing interference fringe failure and its surface state should be (Patent Document 3).

JP-A-5-142791 JP-A-6-59462 JP 2009-237488 A

  The present invention has been made to solve the above problems.

  That is, an object of the present invention is to reduce interference fringes of an electrophotographic photosensitive member having a laminated structure, and there is no white spot failure and an electrophotographic photosensitive member capable of obtaining a high image quality corresponding to the light printing field. It is to provide a body and an image forming method using the body.

  As a result of a detailed study by the present inventor, it has been found that by providing appropriate irregularities on the surface of the charge generation layer, there is a remarkable effect in preventing the occurrence of interference fringes, which is a problem in the present invention, and titanyl phthalocyanine is charged. When used as a generating substance, it has been found that if the type and particle size of the added particles are selected within the scope of the present invention, the occurrence of white spots can also be prevented, leading to the present invention.

That is, the object of the present invention is achieved by adopting the following configuration.
(1)
In an electrophotographic photosensitive member in which at least a charge generation layer and a charge transport layer are laminated in this order on a conductive support, the charge generation layer contains at least titanyl phthalocyanine and particles having a particle diameter d of 0.5 μm or more and 5.0 μm or less. And an electrophotographic photosensitive member, wherein the relationship between the particle diameter d and the film thickness Hd of the charge generation layer is 0.5 <d / Hd <2.
(2)
The electrophotographic photosensitive member according to item (1), wherein the charge generation layer has a surface roughness Rz _jis of 0.5 μm or more and 5.0 μm or less.
(3)
The electrophotographic photosensitive member according to item (1) or (2), wherein the particles are subjected to a surface treatment.
(4)
The electrophotographic photosensitive member according to (3), wherein the surface-treated particles have a hydrophobicity (Methanol wettability) of 45 to 95%.
(5)
The electrophotographic photosensitive member according to any one of (1) to (4) is used and subjected to steps of uniform charging, image exposure, toner development, toner image transfer to an image support, and heat fixing. An image forming method.

  According to the present invention, there is an object to reduce interference fringes of an electrophotographic photosensitive member having a laminated structure, and there is no whiteout failure, and an electrophotographic photosensitive member capable of obtaining a high image quality corresponding to a light printing field, and the like. An image forming method using can be provided.

The figure of the exposure pattern formed in the dot shape which has regularity which is one of the standard screens. 1 is a configuration diagram of a color image forming apparatus using an electrophotographic photosensitive member of the present invention.

  The constitution and effect of the present invention, the compound used and the image forming method will be further described.

  First, the reason why the effects of the present invention can be obtained by adopting the configuration of the present invention is not necessarily clear.

  However, it has been found that the countermeasure against interference fringes, which is a problem in the present invention, is greatly influenced by the shape of the upper surface of the charge generation layer, and it is extremely important to have appropriate irregularities. Further, it has been found that when titanyl phthalocyanine is used as a charge generation material, even if particles are added to the charge generation layer, failures such as white spots are suppressed within the scope of the present invention. This can be said to be against expectations, at least from the point of view of technical common sense.

  As described above, conventionally, a method of suppressing interference fringes by adding particles to the charge generation layer has been known. However, there have been changes to more severe conditions such as higher image quality and the use of special paper (coated paper, etc.), and it has been thought that the conventional technology cannot cope with the prevention of interference fringes. Further, there is a problem that image defects different from interference fringes such as white spots caused by particles are generated only by adding particles.

However, according to this detailed study, when titanyl phthalocyanine (TiOPc) is used as a charge generation material and the additive particle diameter and the film thickness of the charge generation layer have a certain relationship, the anti-interference fringe resistance is improved. Omission defects are also improved. Furthermore, by subjecting the particles added to the charge generation layer to surface treatment, the familiarity with the charge generation layer is improved, the occurrence of other image defects is suppressed, the dispersion stability is high, and the productivity is excellent. The body can be provided.
[Titanylphthalocyanine used in the present invention]
The titanyl phthalocyanine used in the present invention has a peak position at a Bragg angle 2θ (± 0 in the following description) with a measurement error of ± 0.2 ° in an X-ray diffraction spectrum for Cu-Kα rays (wavelength 1.541Å). .2 ° error value is omitted), but the following are preferably used.

  (1) α-type titanyl phthalocyanine having strong peaks at 7.5 °, 12.3 °, 16.3 °, 25.3 ° and 28.7 ° as described in JP-A-61-239248, (2) As described in JP-A-62-67094 and JP-A-63-218768, 9.3 °, 10.6 °, 13.2 °, 15.1 °, 15.7 °, 16.1 °, 20. Β-type titanyl phthalocyanine with strong peaks at 8 °, 23.3 °, 26.3 ° and 27.1 °, (3) as reported in the Journal of the Electrophotographic Society, Vol. 27, No. 4 (p19-24) And m-type titanyl phthalocyanine having a strong peak at 23.4 °, (4) 9.2 °, 11.6 °, 13.0 °, 24.1 °, 26.2 as described in JP-A-2-309362 And I-type titanyl phthalocyanine having strong peaks at ° and 27.2 °. More preferably, titanyl phthalocyanine having strong peaks at 9.6 ° and 27.2 ° (referred to as Y-type titanyl phthalocyanine in the present invention) as used in JP-A Nos. 64-17066 and 3-200790 is used. It is done. The peak of titanyl phthalocyanine according to the present invention is an acute-angled cone-shaped protrusion that is clearly different from noise.

  The basic structure of the titanyl phthalocyanine pigment used in the present invention is represented by the following general formula.

(Wherein X ¹ , X ² , X ³ and X ⁴ each represent a hydrogen atom, a halogen atom, an alkyl group or an alkoxy group, and n, m, l and k each represent an integer of 0 to 4)
In the present invention, titanyl phthalocyanine may be obtained by adding a diol such as butanediol to the structure represented by the above general formula.

As a measuring apparatus for measuring the above X-ray diffraction spectrum, an X-ray diffraction apparatus for measuring a thin film sample using CuKα rays monochromatically parallelized by an artificial multilayer film mirror as a radiation source is used. For example, “Rigaku RINT2000 (Rigaku Corporation)” and the like can be mentioned. The measurement conditions for the X-ray diffraction spectrum are as follows. That is,
X-ray output voltage: 50 kV
X-ray output current: 250 mA
Fixed incident angle (θ): 1.0 °
Scanning range (2θ): 5 to 35 °
Scan step width: 0.05 °
Incident solar slit: 5.0 °
Incident slit: 0.1 mm
Receiving solar slit: 0.1 °
It is possible to measure the X-ray diffraction spectrum by setting the above measurement conditions.

Next, a method for producing the titanyl phthalocyanine used in the present invention will be described. For example, 1,3-diiminoisoindoline and sulfolane are mixed, and titanium tetrapropoxide is added thereto and reacted under a nitrogen atmosphere. The reaction temperature is 80 ° C to 300 ° C, and 100 ° C to 260 ° C is particularly preferable. After completion of the reaction, the mixture is allowed to cool, and the precipitate is collected by filtration to obtain titanyl phthalocyanine. Next, the target titanyl phthalocyanine can be obtained by treating this with a mixed solvent, but as a device used for the treatment, in addition to a general stirring device, a homomixer, a disperser, an agitator, or a ball mill, a sand mill, an attritor Etc. can be used.
[Particles added to the charge generation layer]
Particles added to the charge generation layer used in the present invention include fine resin powder (for example, fluorine resin, polyolefin resin, silicone resin, melamine resin, urea resin, acrylic resin, styrene resin, etc.), metal oxide Fine powder (for example, silicon oxide, titanium oxide, aluminum oxide, tin oxide, etc.), solid lubricant (for example, polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinylidene fluoride, zinc stearate, aluminum stearate, etc.), Fluorine resin powder (eg, ethylene tetrafluoride resin powder, ethylene trifluoride chloride resin powder, hexafluoroethylene propylene resin powder, vinyl fluoride resin powder, vinylidene fluoride resin powder, fluoride Ethylene dichloride resin powder and copolymers thereof), polyolefin resin powder (for example, poly Homopolymer resin powder such as ethylene resin powder, polypropylene resin powder, polybutene resin powder, polyhexene resin powder, copolymer resin powder such as ethylene-propylene copolymer, ethylene-butene copolymer, and these and hexene And polyolefin resin powders such as these heat-modified products). Among these, resin fine powder is preferable from the viewpoint of dispersion stability and the like.

  The particle diameter d of the particles added to the charge generation layer is 0.5 μm or more and 5.0 μm or less, and the relationship with the film thickness Hd of the charge generation layer is 0.5 <d / Hd <2. When the particle diameter d is smaller than 0.5 μm or d / Hd is 0.5 or less, the upper surface of the charge generation layer is not sufficiently provided with unevenness, and the interference fringe suppressing effect is not exhibited. On the other hand, when the particle diameter d is larger than 5.0 μm or d / Hd is 2 or more, the unevenness provided on the upper surface of the charge generation layer is large, and image defects other than interference fringes such as white spots occur. In a preferred range of the present invention, the particle diameter d is 0.5 μm or more and 2.0 μm or less, and the relationship with the film thickness Hd of the charge generation layer is 0.5 <d / Hd <2.

  Here, the particle diameter in the present invention is a 50% particle diameter based on the number. For the measurement of the particle diameter, a method capable of appropriately measuring may be used. For example, by taking a section of the cross section of the charge generation layer, from a photograph taken with a transmission electron microscope (TEM), 100 additive particles are randomly selected and the maximum diameter of the primary particles (any two points on the outer contour line of the particles) It is possible to measure and determine the length when the length between them is selected to be maximum.

  In the present invention, the particles added to the charge generation layer are preferably subjected to a surface treatment. The surface treatment agent according to the present invention typically includes reactive silicone oil, silane coupling agent, titanium coupling agent, aluminum coupling agent, zirconium coupling agent, etc., and silicon, titanium, aluminum, zirconium It has a hydrolyzable group having affinity or reactivity with the charge generation layer-added particles through atoms. Among these, the surface treatment is preferably performed with a reactive silicone oil or a silane coupling agent.

  Examples of the reactive silicone oil include polysiloxane compounds. The molecular weight of the polysiloxane compound is generally easily available from 1000 to 20000. In particular, when methyl hydrogen polysiloxane is used, a good effect can be obtained.

  The silane coupling agent is preferably a compound represented by the following general formula (1), but is not limited to the following compounds as long as it is a compound that undergoes a condensation reaction with a reactive group such as a hydroxyl group on the particle surface. Examples of such compounds include silyl compounds.

General formula (1)
(R) _j -Si- (X) _4-j
(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 j represents an integer of 0 to 3.)
In the silane coupling agent represented by the general formula (1), an organic group in which carbon is directly bonded to silicon represented by R includes alkyl groups such as methyl, ethyl, propyl, and butyl, phenyl, tolyl, and naphthyl. Aryl groups such as biphenyl, epoxy-containing groups such as γ-glycidoxypropyl, β- (3,4-epoxycyclohexyl) ethyl, (meth) acryloyl groups such as γ-acryloxypropyl and γ-methacryloxypropyl , Γ-hydroxypropyl, hydroxyl group such as 2,3-dihydroxypropyloxypropyl, vinyl group such as vinyl and propenyl, mercapto group such as γ-mercaptopropyl, γ-aminopropyl, N-β (aminoethyl) -Amino-containing groups such as γ-aminopropyl, γ-chloropropyl, 1,1,1-trifluoropropyl, Fluorohexyl, halogen-containing groups such as perfluorooctylethyl, other nitro, and cyano-substituted alkyl group. In particular, alkyl groups such as methyl, ethyl, propyl and butyl are preferred. Examples of the hydrolyzable group for X include alkoxy groups such as methoxy and ethoxy, halogen groups, and acyloxy groups. In particular, an alkoxy group having 6 or less carbon atoms is preferable.

  Moreover, the silane coupling agent represented by General formula (1) may be individual, and may be used in combination of 2 or more types. However, at least one of the silane coupling agents represented by the general formula (1) used is preferably a silane coupling agent having j of 1 to 3.

  Moreover, when j is 2 or more in the specific compound of the silane coupling agent represented by the general formula (1), a plurality of R may be the same or different. Similarly, when j is 2 or less, the plurality of Xs may be the same or different. Moreover, when using 2 or more types of silane coupling agents represented by General formula (1), R and X may be the same between each compound, and may differ.

  Examples of compounds in which j is 0 include the following compounds.

  Tetrachlorosilane, diethoxydichlorosilane, tetramethoxysilane, phenoxytrichlorosilane, tetraacetoxysilane, tetraethoxysilane, tetraallyloxysilane, tetrapropoxysilane, tetraisopropoxysilane, tetrakis (2-methoxyethoxy) silane, tetrabutoxysilane , Tetraphenoxysilane, tetrakis (2-ethylbutoxy) silane, and tetrakis (2-ethylhexyloxy) silane.

  Examples of the compound in which j is 1 include the following compounds.

  Trichlorosilane, methyltrichlorosilane, vinyltrichlorosilane, ethyltrichlorosilane, allyltrichlorosilane, n-propyltrichlorosilane, n-butyltrichlorosilane, chloromethyltriethoxysilane, methyltrimethoxysilane, mercaptomethyltrimethoxysilane, trimethoxy Vinylsilane, ethyltrimethoxysilane, 3,3,4,4,5,5,6,6,6-nonafluorohexyltrichlorosilane, phenyltrichlorosilane, 3,3,3-trifluoropropyltrimethoxysilane, 3- Chloropropyltrimethoxysilane, triethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 2-aminoethylaminomethyltrimethoxysilane, benzylto Chlorosilane, methyltriacetoxysilane, chloromethyltriethoxysilane, ethyltriacetoxysilane, phenyltrimethoxysilane, 3-allylthiopropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-bromopropyltriethoxysilane, 3-allylaminopropyltrimethoxysilane, propyltriethoxysilane, hexyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-methacryloxypropyltrimethoxysilane, bis (ethylmethylketoxime) methoxymethylsilane, pentyltriethoxy Examples include silane, octyltriethoxysilane, dodecyltriethoxysilane, and the like.

  Examples of the compound wherein j is 2 include the following compounds.

  Dimethyldichlorosilane, dimethoxymethylsilane, dimethoxydimethylsilane, methyl-3,3,3-trifluoropropyldichlorosilane, diethoxysilane, diethoxymethylsilane, dimethoxymethyl-3,3,3-trifluoropropylsilane, 3 -Chloropropyldimethoxymethylsilane, chloromethyldiethoxysilane, diethoxydimethylsilane, dimethoxy-3-mercaptopropylmethylsilane, 3,3,4,4,5,5,6,6,6-nonafluorohexylmethyldi Chlorosilane, methylphenyldichlorosilane, diacetoxymethylvinylsilane, diethoxymethylvinylsilane, 3-methacryloxypropylmethyldichlorosilane, 3-aminopropyldiethoxymethylsilane, 3- (2-aminoethylaminopropyl) Pill) dimethoxymethylsilane, t-butylphenyldichlorosilane, 3-methacryloxypropyldimethoxymethylsilane, 3- (3-cyanopropylthiopropyl) dimethoxymethylsilane, 3- (2-acetoxyethylthiopropyl) dimethoxymethylsilane, Dimethoxymethyl-2-piperidinoethylsilane, dibutoxydimethylsilane, 3-dimethylaminopropyldiethoxymethylsilane, diethoxymethylphenylsilane, diethoxy-3-glycidoxypropylmethylsilane, 3- (3-acetoxypropyl) And thio) propyldimethoxymethylsilane, dimethoxymethyl-3-piperidinopropylsilane, and diethoxymethyloctadecylsilane.

  Examples of the compound in which j is 3 include the following compounds.

  Examples include trimethylchlorosilane, methoxytrimethylsilane, ethoxytrimethylsilane, methoxydimethyl-3,3,3-trifluoropropylsilane, 3-chloropropylmethoxydimethylsilane, and methoxy-3-mercaptopropylmethylmethylsilane.

  The silane coupling agent represented by the general formula (1) is preferably a silane coupling agent represented by the following general formula (2).

General formula (2)
R-Si-X ₃
(In the formula, R represents an alkyl group, an aryl group, and X represents a methoxy group, an ethoxy group, or a halogen group.)
In the silane coupling agent represented by the general formula (2), a silane coupling agent in which R is an alkyl group having 4 to 8 carbon atoms is more preferable. Examples include methoxysilane, i-butyltrimethoxysilane, hexyltrimethoxysilane, and octyltrimethoxysilane.

  Another surface treatment of the particles of the present invention is based on a silane coupling agent having a fluorine atom. Examples of the silane coupling agent having a fluorine atom include 3,3,4,4,5,5,6,6,6-nonafluorohexyltrichlorosilane, 3,3,3-trifluoropropyltrimethoxysilane, methyl- 3,3,3-trifluoropropyldichlorosilane, dimethoxymethyl-3,3,3-trifluoropropylsilane, 3,3,4,4,5,5,6,6,6-nonafluorohexylmethyldichlorosilane Etc.

  Titanium coupling agents include isopropyl triisostearoyl titanate, isopropyl tridodecylbenzenesulfonyl titanate, isopropyl tri (dioctyl pyrophosphate) titanate, tetraisopropyl bis (dioctyl phosphite) titanate, tetraoctyl bis (ditridecyl phosphite) titanate, Examples include tetra (2,2-diallyloxymethyl-1-butyl) -bis (ditridecyl phosphite) titanate, bis (dioctyl pyrophosphate) -oxyacetate titanate, and bis (dioctyl pyrophosphate) ethylene titanate.

  Examples of the aluminum coupling agent include acetoalkoxyaluminum diisopropylate.

  Zirconium tetraacetylacetonate, zirconium tributoxy monoacetylacetonate, zirconium monobutoxyacetylacetonate bis (ethylacetoacetate), zirconium dibutoxybis (ethylacetoacetate), zirconium tetraacetylacetate Nate, zirconium tributoxy monostearate and the like.

  The above surface treatment agents can be used alone or in admixture of two or more.

  When mixing and using 2 or more types, it can be used in arbitrary ratios.

  The surface treatment of the present invention is preferably performed by a wet method. That is, the surface treatment agent is dissolved or suspended in an organic solvent or water, particles are added thereto, and such a solution is stirred and mixed for about several minutes to 1 hour. After the application, it is dried through a process such as filtration, and the particle surface is treated. The surface treatment agent may be added to a suspension in which particles are dispersed in an organic solvent or water.

  Moreover, you may perform inorganic processes, such as an alumina process, a silica process, a zirconia process, before said process. Alumina treatment, silica treatment, and zirconia treatment are treatments for precipitating alumina, silica, or zirconia on the particle surface. Alumina, silica, zirconia hydrated on alumina, silica, zirconia on these surfaces Things are also included.

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

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

0.2 g of 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 the liquid, with gentle stirring until the entire particle is wet. When the amount of methanol necessary to completely wet the particles is a (ml), the degree of hydrophobicity is calculated by the above formula. In the present invention, the preferred range of the degree of hydrophobicity is 45 to 95%.
[Configuration of photoconductor]
The structure of an electrophotographic photoreceptor (also referred to as a photoreceptor or an organic photoreceptor) preferably used in the present invention is described below.

  The organic photoreceptor of the present invention has a laminated photosensitive layer including at least a charge generation layer and a charge transport layer in this order on a conductive support. Moreover, the structure which provided the protective layer in the intermediate | middle layer or the outermost surface as needed may be sufficient. Specifically, the layer configuration as shown below can be exemplified.

  A layer structure in which a charge generation layer and a charge transport layer are sequentially laminated on a conductive substrate, or a layer structure in which an intermediate layer, a charge generation layer, a charge transport layer, and a protective layer are sequentially laminated on a conductive support. Have

  Hereinafter, the layer structure of the organic photoreceptor will be mainly described.

(Conductive support)
The conductive support (also referred to as a conductive substrate) used in the present invention may be any one as long as it has conductivity. For example, a metal such as aluminum, copper, chromium, nickel, zinc, and stainless steel is drum or sheet. Molded into a shape, laminated with a metal foil such as aluminum or copper on a plastic film, deposited with aluminum, indium oxide, tin oxide, etc. on a plastic film, conductive by applying a conductive substance alone or with a binder resin Examples include a metal provided with a layer, a plastic film, and paper.

(Middle layer)
In the present invention, an intermediate layer having a barrier function and an adhesive function may be provided between the conductive layer and the photosensitive layer. Considering various types of failure prevention, it can be said that providing an intermediate layer is a preferable mode.

  The intermediate layer can be formed by dip coating or the like by dissolving a binder resin such as casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, polyamide, polyurethane and gelatin in a known solvent. Of these, an alcohol-soluble polyamide resin is preferred.

  Moreover, various fine particles (metal oxide particles and the like) can be contained for the purpose of adjusting the resistance of the intermediate layer. For example, using various metal oxides such as alumina, zinc oxide, titanium oxide, tin oxide, antimony oxide, indium oxide, and bismuth oxide, fine particles such as indium oxide doped with tin, tin oxide doped with antimony, and zirconium oxide. Can do.

  You may use these metal oxides 1 type or in mixture of 2 or more types. When two or more types are mixed, it may take the form of a solid solution or fusion. The average particle diameter of such a metal oxide is preferably 0.3 μm or less, more preferably 0.1 μm or less. These metal oxide particles may be surface-treated with an inorganic compound or an organic compound.

  As the solvent used for the intermediate layer, a solvent in which inorganic particles are well dispersed and the polyamide resin is dissolved is preferable. Specifically, alcohols having 1 to 4 carbon atoms such as methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol, t-butanol and sec-butanol are excellent in solubility and coating performance of polyamide resin. preferable. In addition, examples of co-solvents that can be used in combination with the above-described solvent to obtain favorable effects in order to improve the storage stability and particle dispersibility include benzyl alcohol, toluene, methylene chloride, cyclohexanone, and tetrahydrofuran.

  The density | concentration of binder resin is suitably selected according to the film thickness and production rate of an intermediate | middle layer.

  The mixing ratio of the inorganic particles to the binder resin when the inorganic particles are dispersed is preferably 20 to 400 parts by mass, more preferably 50 to 200 parts by mass with respect to 100 parts by mass of the binder resin.

  As a means for dispersing the inorganic particles, an ultrasonic disperser, a ball mill, a sand grinder, a homomixer, or the like can be used, but is not limited thereto.

  The method for drying the intermediate layer can be appropriately selected according to the type of solvent and the film thickness, but thermal drying is preferred.

  The thickness of the intermediate layer is preferably from 0.1 to 30 μm, more preferably from 0.3 to 15 μm.

(Charge generation layer)
The charge generation layer used in the present invention has a titanyl phthalocyanine as a charge generation substance and a particle diameter d of 0.5 μm or more and 5.0 μm or less, and the relationship with the film thickness Hd of the charge generation layer is 0.5 <d / It preferably contains particles having a Hd <2 and a binder resin, and is formed by dispersing and coating the charge generation material and the particles in a binder resin solution.

  As long as the charge generation material does not impair the effects of the present invention, azo raw materials such as Sudan Red and Diane Blue, quinone pigments such as pyrenequinone and anthanthrone, quinocyanine pigments, perylene pigments, indigo pigments such as indigo and thioindigo, A phthalocyanine pigment or the like may be used in combination. These charge generation materials can be added in a form dispersed in a known resin.

  As the binder resin of the charge generation layer, a known resin can be used, for example, polystyrene resin, polyethylene resin, polypropylene resin, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, polyvinyl butyral resin, epoxy resin, Polyurethane resins, phenol resins, polyester resins, alkyd resins, polycarbonate resins, silicone resins, melamine resins, and copolymer resins containing two or more of these resins (eg, vinyl chloride-vinyl acetate copolymer resins, chlorides) Vinyl-vinyl acetate-maleic anhydride copolymer resin) and poly-vinylcarbazole resin, but are not limited thereto.

  The charge generation layer is formed by dispersing a charge generation material and the above particles in a solution in which a binder resin is dissolved in a solvent by using a disperser to prepare a coating solution, and then applying the coating solution to a certain film thickness by using a coating device. It is preferable that the coating film is prepared by drying. In addition to the above method, the coating solution is prepared by dispersing the charge generating substance in a solution in which the binder resin is dissolved, and then adding the above particles to further disperse, or in the solution in which the binder resin is dissolved. You may carry out by the method etc. which mix the liquid which disperse | distributed the charge generation substance, and the liquid which disperse | distributed said particle | grains.

  Solvents for dissolving and coating the binder resin used in the charge generation layer include, for example, toluene, xylene, methylene chloride, 1,2-dichloroethane, methyl ethyl ketone, cyclohexane, ethyl acetate, butyl acetate, methanol, ethanol, propanol, Examples include butanol, methyl cellosolve, ethyl cellosolve, tetrahydrofuran, 1-dioxane, 1,3-dioxolane, pyridine, and diethylamine, but are not limited thereto.

  As a means for dispersing the charge generation material and the particles, an ultrasonic disperser, a ball mill, a sand grinder, a homomixer, and the like can be used, but are not limited thereto.

  The mixing ratio of the charge generating material to the binder resin is preferably 1 to 600 parts by weight, more preferably 50 to 500 parts by weight based on 100 parts by weight of the binder resin. Moreover, it is preferable that the ratio of the particle | grains added to a charge generation layer is 1-30 mass% of solid content contained in a charge generation layer, More preferably, it is 5-20 mass%. The film thickness of the charge generation layer varies depending on the particle diameter of the particles added to the charge generation layer, but is preferably 0.25 to 10 μm. Note that a method capable of appropriately measuring the thickness of the charge generation layer may be used. For example, by taking a section of the cross section of the charge generation layer and measuring the film thickness of 20 portions not containing the additive particles at random from a photograph taken with a transmission electron microscope (TEM), the average value can be obtained.

In addition, so-called ten-point average roughness (Rz _cis ) is used for measuring the surface shape of the charge generation layer. This measurement can be performed using a laser microscope that can be measured in a non-contact manner by preparing a sample in which a charge generation layer is formed on a conductive support. Rz _jis is preferably 0.5 μm or more and 5.0 μm or less, more preferably 0.8 μm or more and 1.5 μm or less.

(Charge transport layer)
The charge transport layer used in the photoreceptor of the present invention contains a charge transport material (CTM) and a binder resin, and is formed by dissolving and coating the charge transport material in a binder resin solution.

  Examples of charge transport materials include carbazole derivatives, oxazole derivatives, oxadiazole derivatives, thiazole derivatives, thiadiazole derivatives, triazole derivatives, imidazole derivatives, imidazolone derivatives, imidazolidine derivatives, bisimidazolidine derivatives, styryl compounds, hydrazone compounds, pyrazoline compounds Oxazolone derivatives, benzimidazole derivatives, quinazoline derivatives, benzofuran derivatives, acridine derivatives, phenazine derivatives, aminostilbene derivatives, triarylamine derivatives, phenylenediamine derivatives, stilbene derivatives, benzidine derivatives, poly-N-vinylcarbazole, poly-1- Two or more kinds of vinylpyrene, poly-9-vinylanthracene, triphenylamine derivatives and the like may be mixed and used.

  A known resin can be used as the binder resin for the charge transport layer, and polycarbonate resin, polyarylate resin, polyester resin, polystyrene resin, styrene-acrylonitrile copolymer resin, polymethacrylate resin, and styrene-methacrylic acid. Examples include ester copolymer resins, and polycarbonate is preferred. Further, BPA, BPZ, dimethyl BPA, BPA-dimethyl BPA copolymer and the like are preferable in terms of crack resistance, wear resistance, and charging characteristics.

  The charge transport layer is preferably formed by dissolving the binder resin and the charge transport material to prepare a coating solution, applying the coating solution to a certain film thickness with a coating machine, and drying the coating film.

  Examples of the solvent for dissolving the binder resin and the charge transport material include toluene, xylene, methylene chloride, 1,2-dichloroethane, methyl ethyl ketone, cyclohexanone, ethyl acetate, butyl acetate, methanol, ethanol, propanol, butanol, and tetrahydrofuran. 1,4-dioxane, 1,3-dioxolane, pyridine, diethylamine, and the like, but are not limited thereto.

  The mixing ratio of the charge transport material to the binder resin is preferably 10 to 500 parts by mass, more preferably 20 to 100 parts by mass with respect to 100 parts by mass of the binder resin.

  The thickness of the charge transport layer varies depending on the characteristics of the charge transport material, the characteristics of the binder resin, the mixing ratio, and the like, but is preferably 5 to 40 μm, and more preferably 10 to 30 μm.

  An antioxidant, an electronic conductive agent, a stabilizer and the like may be added to the charge transport layer. As the antioxidant, those described in JP-A No. 2000-305291, and as the electronic conductive agent, those described in JP-A Nos. 50-137543 and 58-76483 are preferable.

(Protective layer)
The protective layer used in the photoreceptor of the present invention is formed by applying a coating solution prepared by adding inorganic fine particles to a binder resin on a charge transport layer. The protective layer may contain an antioxidant, a lubricant and the like.

  Inorganic fine particles include silica, alumina, strontium titanate, zinc oxide, titanium oxide, tin oxide, antimony oxide, indium oxide, bismuth oxide, indium oxide doped with tin, tin oxide doped with antimony and tantalum, zirconium oxide, etc. These fine particles can be preferably used. In particular, hydrophobic silica, hydrophobic alumina, hydrophobic zirconia, fine powder sintered silica and the like whose surface has been hydrophobized are preferable.

  The number average primary particle size of the inorganic fine particles is preferably 1 to 300 nm, particularly preferably 5 to 100 nm. The number average primary particle diameter of the inorganic fine particles is magnified 10,000 times by observation with a transmission electron microscope, 300 particles are randomly observed as primary particles, and the measured value is calculated as the number average diameter of the ferret diameter by image analysis. Is the value obtained.

  The binder resin used for the protective layer may be either a thermoplastic resin or a thermosetting resin. For example, polyvinyl butyral resin, epoxy resin, polyurethane resin, phenol resin, polyester resin, alkyd resin, polycarbonate resin, silicone resin, melamine resin, and the like can be given.

  Examples of the lubricant used in the protective layer include fine resin powder (for example, fluorine resin, polyolefin resin, silicone resin, melamine resin, urea resin, acrylic resin, styrene resin), metal oxide fine powder (for example, titanium oxide). , Aluminum oxide, tin oxide, etc.), solid lubricant (eg, polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinylidene fluoride, zinc stearate, aluminum stearate, etc.), silicone oil (eg, dimethyl silicone oil, methyl) Phenyl silicone oil, methyl hydrogen polysiloxane, cyclic dimethyl polysiloxane, alkyl modified silicone oil, polyether modified silicone oil, alcohol modified silicone oil, fluorine modified silicone oil, amino modified silicone , Mercapto-modified silicone oil, epoxy-modified silicone oil, carboxyl-modified silicone oil, higher fatty acid-modified silicone oil, etc.), fluorine-based resin powder (for example, tetrafluoroethylene resin powder, ethylene trifluoride chloride resin powder, Hexafluoroethylene propylene resin powder, vinyl fluoride resin powder, vinylidene fluoride resin powder, fluorinated ethylene chloride resin powder and copolymers thereof, polyolefin resin powder (for example, polyethylene resin) Homopolymer resin powder such as powder, polypropylene resin powder, polybutene resin powder, polyhexene resin powder, copolymer resin powder such as ethylene-propylene copolymer, ethylene-butene copolymer, and hexene Polyolefins such as terpolymers and their thermal modifications Shifun and the like) and the like.

  The molecular weight of each resin used in the lubricant and the particle size of the powder can be selected as appropriate. The particle size is particularly preferably 0.1 μm to 10 μm. In order to disperse these lubricants uniformly, a dispersant may be added to the binder resin.

[Toner and developer]
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.

  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.
(Image forming method)
Next, an image forming apparatus used in an image forming method using the electrophotographic photosensitive member of the present invention will be described.

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

  In the image forming apparatus of the present invention, it is desirable to use a semiconductor laser or light emitting diode having an oscillation wavelength of 350 to 850 nm as an image exposure light source when an electrostatic latent image is formed on a photoreceptor. By using these image exposure light sources, the exposure dot diameter in the writing principal direction is narrowed down to 10 to 100 μm, and digital exposure is performed on the organic photoreceptor, so that 600 dpi (dpi: number of dots per 2.54 cm) to 2400 dpi. Or higher-resolution electrophotographic images can be obtained.

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

The light beams used have a scanning optical system and LED solid scanner such as 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.

  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 unit 3Y, a unit composed of LEDs and light-emitting elements in which light emitting elements are arranged in an array in the axial direction of the photosensitive drum 1Y, 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 charging device, an image exposure device, a developing device, a transfer or separation device, and a cleaning device is integrally supported together with a photosensitive member to form a process cartridge (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.

  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. The present invention can be widely applied to such devices.

  Next, representative embodiments of the present invention will be shown and the present invention will be further described. However, it is needless to say that the embodiments of the present invention are not limited thereto.

In the text, “part” means “part by mass”.
Example 1 (Photoreceptor 1)
<Preparation of conductive support>
An aluminum alloy element tube with a length of 362 ± 0.2mm is attached to the NC _lathe , and the outer diameter is 59.95 ± _0.04mm and the surface Rz _jis is 0.1 ± _0.05μm with a diamond sintered tool. Cutting was performed so as to be.

<Preparation of Photoreceptor 1>
(Formation of intermediate layer)
3. 1 part by mass of binder resin (N-1) below is added to 20 parts by mass of ethanol / n-propyl alcohol / tetrahydrofuran (45:20:35 volume ratio) and dissolved by stirring, and then titanium oxide particles SMT500SAS (manufactured by Teika). 2 parts by mass were mixed, and the mixed solution was dispersed by a bead mill with a mill residence time of 3 hours to prepare an intermediate layer coating solution. After the same solution is filtered through a 5 μm filter, the intermediate layer coating solution is applied to the outer periphery after washing the substrate by a dip coating method, dried at 120 ° C. for 30 minutes, and an “intermediate layer” having a dry film thickness of 2 μm. Formed.

(Formation of charge generation layer)
The following components were mixed and dispersed for 15 hours using a sand mill disperser to prepare a charge generation layer coating solution. This coating solution was applied onto the intermediate layer by a dip coating method to form a “charge generation layer” having a dry film thickness of 0.5 μm.

Y-type titanyl phthalocyanine (A-1; titanyl phthalocyanine pigment having a maximum diffraction peak at a Bragg angle (2θ ± 0.2 °) of 27.3 ° in an X-ray diffraction spectrum by Cu-Kα characteristic X-ray) ... 20 parts by weight Polyvinyl butyral (BX-1, manufactured by Sekisui Chemical Co., Ltd.) ... 10 parts by weight Silicone resin fine particles (XC99-A8808; particles 0.7μm in diameter, manufactured by Momentive Performance Materials Japan GK) ······ 5 parts by weight Methyl ethyl ketone ···················· 700 parts by weight ... 300 parts by mass

(Formation of 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 and dried at 120 ° C. for 70 minutes to form a “charge transport layer” having a dry film thickness of 20 μm.

Charge transport material (structure below): 50 parts by weight Polycarbonate resin “Iupilon-Z300” (Mitsubishi Gas Chemical Co., Ltd.) 100 parts by weight Antioxidant (2,6 -Di-t-butyl-4-methylphenol) 8 parts by mass Tetrahydrofuran / toluene (volume ratio 8/2) 750 parts by mass

Example 2 (Photoreceptor 2)
The silicone resin fine particles added to the charge generation layer and the dry film thickness in Example 1 were changed to silicone resin fine particles (Tospearl 145; particle diameter 4.5 μm, manufactured by Momentive Performance Materials Japan GK) and 3.0 μm. An electrophotographic photosensitive member was produced in the same manner as Example 1 except for the above.
Example 3 (Photoreceptor 3)
The surface of silicone resin fine particles (XC99-A8808, manufactured by Momentive Performance Materials Japan GK) was treated with 3% hexyltrimethoxysilane to obtain surface-treated silicone fine particles (particle diameter 0.7 μm). . An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the silicone fine particles added to the charge generation layer and the dry film thickness in Example 1 were changed to 0.7 μm for the surface-treated silicone fine particles.
Examples 4 to 12 (Photoconductors 4 to 12)
The surface-treated silicone resin fine particles were obtained by changing the surface-treated silicone resin fine particle species and surface treatment in Example 3 as shown in Table 1. An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the silicone resin fine particles added to the charge generation layer in Example 1 were changed to the surface-treated silicone fine particles and the dry film thickness was changed as shown in Table 1. .
Example 13 (Photoreceptor 13)
The surface-treated particles were obtained by changing the surface-treated silicone resin fine particles in Example 3 to silicon oxide particles (SO-03; particle size 0.9 μm, manufactured by Admatechs Co., Ltd.).

An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the silicone resin fine particles added to the charge generation layer in Example 1 were changed to the surface-treated particles and the dry film thickness was changed to 0.6 μm. It was.
Comparative Example 1 (Photoreceptor 14)
The surface-treated particles were obtained by changing the surface-treated silicone resin fine particles in Example 3 to styrene acrylic particles (MG-161; particle size 0.1 μm, manufactured by Nippon Paint Co., Ltd.).

An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the silicone resin fine particles added to the charge generation layer in Example 1 were changed to the surface-treated particles and the dry film thickness was changed to 0.1 μm. It was.
Comparative Example 2 (Photoreceptor 15)
The surface-treated particles were obtained by changing the surface-treated silicone resin fine particles in Example 3 to silicone resin fine particles (Tospearl 2000B; particle size 6.0 μm, manufactured by Momentive Performance Materials Japan GK).

An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the silicone resin fine particles added to the charge generation layer in Example 1 were changed to the surface-treated particles and the dry film thickness was changed to 0.1 μm. 15 was obtained.
Comparative Example 3 (Photoreceptor 16)
An electrophotographic photosensitive member was produced in the same manner as in Example 3 except that the dry film thickness was changed to 0.3 μm in Example 3, and a photosensitive member 16 was obtained.
Comparative Example 4 (Photoconductor 17)
An electrophotographic photosensitive member was produced in the same manner as in Example 3 except that the dry film thickness was changed to 2.0 μm in Example 3 to obtain a photosensitive member 17.
Comparative Example 5 (Photoreceptor 18)
In Example 3, an electrophotographic photosensitive member was produced in the same manner as in Example 3 except that Y-type titanyl phthalocyanine was changed to an azo pigment represented by the following structural formula (B-1) to obtain a photosensitive member 18. .

Comparative Example 6 (Photoconductor 19)
In Comparative Example 3, an electrophotographic photosensitive member was produced in the same manner as in Comparative Example 3 except that the surface-treated silicone resin fine particles were not added, and a photosensitive member 19 was obtained.

The type of charge generation material (CGM) used for the charge generation layer (CGL) of the above photoreceptors 1 to 19, the particle diameter d (μm) of the added particles, the type of surface treatment of the added particles, the degree of hydrophobicity, and the film thickness Hd (μm), d / Hd, surface roughness Rz _jis (μm), and inside / outside of the present invention (comparative example) are collectively shown in Table 1.

Surface treatment A: Mass ratio 3% hexyltrimethoxysilane treatment Surface treatment B: Mass ratio 3% aminotrimethoxysilane treatment Surface treatment C: Mass ratio 10% fluorinated methyltrimethoxysilane treatment Surface roughness of the charge generation layer Is a value of Rz _jis measured using a laser microscope VK-9700 manufactured by Keyence Co., Ltd., and the degree of hydrophobicity is a value obtained by the measurement method described above.

<Performance evaluation>
For performance evaluation, bizhub PRO C6501 manufactured by Konica Minolta Business Technologies, Ltd. was used.

(Interference fringes)
Performed by visual evaluation of the halftone image output using the exposure pattern A (FIG. 1, various densities) and “POD gloss coat (100 g / m ² )” manufactured by Oji Paper Co., Ltd. at the black (Bk) position. It was.

○: Interference fringes are not recognized △: Interference fringes are slightly recognized, but there is no problem in practical use ×: Interference fringes are recognized (white spots)
Table 2 shows the results of evaluation based on the following criteria.

○: No image defect occurred △: Image defect occurred slightly, but there was no problem in actual use ×: Image defect occurred and there was problem in actual use (dispersion stability)
Further, the dispersion stability was evaluated by comparing and evaluating the degree of sedimentation of the added particles by allowing the charge generation layer coating solutions of the photoreceptors 1 to 19 to stand in a glass beaker for 2 days.

○: No sedimentation △: Slightly settled but returns to the original state by stirring. ×: Sedimentation is observed and does not return even after stirring. But practical application is possible.

As apparent from the results of the performance evaluation shown in Table 2, the relationship between titanyl phthalocyanine as the charge generation material and the particle diameter d of 0.5 to 5 μm and the thickness Hd of the charge generation layer is 0.5 <d / Photoconductors 1 to 13 containing particles with Hd <2 can achieve the object of the present invention. However, it can be seen that the photoreceptors 14 to 19 from which any of the above-described conditions of the present invention are at least problematic. In addition, a photoconductor including particles having a surface roughness Rz _jis of 0.5 to _5.0 μm and surface treatment, or particles having a degree of hydrophobicity of 45 to 95%, within the present invention, Excellent white spot resistance and dispersion stability.

1Y, 1M, 1C, 1Bk photoconductor 2Y, 2M, 2C, 2Bk charging unit 3Y, 3M, 3C, 3Bk exposure unit 4Y, 4M, 4C, 4Bk developing unit 10Y, 10M, 10C, 10Bk image forming unit

Claims (5)

  In the electrophotographic photosensitive member in which at least a charge generation layer and a charge transport layer are laminated in this order on a conductive support, the charge generation layer has at least titanyl phthalocyanine and particles having a particle diameter d of 0.5 μm or more and 5.0 μm or less. And a relationship between the particle diameter d and the film thickness Hd of the charge generation layer is 0.5 <d / Hd <2. 2. The electrophotographic photosensitive member according to claim 1, wherein the charge generation layer has a surface roughness Rz _jis of 0.5 μm or more and 5.0 μm or less.   The electrophotographic photosensitive member according to claim 1, wherein the particles are subjected to a surface treatment.   The electrophotographic photosensitive member according to claim 3, wherein the surface-treated particles have a hydrophobicity (Methanol Wettability) of 45 to 95%.   5. The electrophotographic photosensitive member according to claim 1, wherein the electrophotographic photosensitive member is subjected to steps of uniform charging, image exposure, toner development, toner image transfer to an image support, and heat fixing. Image forming method.

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