JP6003176B2 - Electrophotographic photoreceptor and image forming apparatus - Google Patents

Description

  The present invention relates to an electrophotographic photosensitive member used in an electrophotographic image forming method and an image forming apparatus including the electrophotographic photosensitive member.

  In recent years, there has been a demand for higher image quality in image forming apparatuses such as electrophotographic copying machines and printers. Specifically, the demand for higher image quality includes improving density unevenness within a page or between pages. In the image forming apparatus, as the image to be formed has been improved in image quality and resolution, cases of density unevenness are increasing due to improved detection. In order to improve density unevenness, various countermeasures have been taken in image forming apparatuses and are being studied continuously.

  Further, an electrophotographic photosensitive member having a negatively charged laminated structure that has been widely used in recent years is usually formed by forming an intermediate layer on a conductive support and a charge transport layer on a charge generation layer. A photosensitive layer is laminated. In an electrophotographic photosensitive member having such a negatively charged laminate structure, when the surface is negatively charged and then exposed, a charge is generated in the charge generation layer, of which negative charges (electrons) are It moves to the conductive support through the intermediate layer, while holes move to the surface of the electrophotographic photosensitive member through the charge transport layer, canceling the negative charges on the surface and forming an electrostatic latent image. . Therefore, the intermediate layer has an electron transport property (moves electrons generated in the charge generation layer by exposure to the conductive support quickly) and has a hole blocking property (photosensitive from the conductive support). Suppression of hole injection into the layer) is required.

  As a conventional attempt to reduce density unevenness, an electrophotographic photoreceptor is known in which an intermediate layer contains N-type semiconductor fine particles having a hydrophobization degree of 40 to 95, and the contact potential difference with respect to the aluminum deposition surface of the intermediate layer is in a specific range. (Patent Document 1 below). Patent Document 1 discloses that by providing such an intermediate layer, image defects can be reduced particularly under high temperature and high humidity or low temperature and low humidity.

  As another attempt to reduce image defects such as dielectric breakdown and black spots in addition to the transfer memory (corresponding to density unevenness), the number average primary particles having a hydrophobicity of 10 to 50 in the intermediate layer of the electrophotographic photosensitive member. A conventional technique is known in which N-type semiconducting particles having a specific range of diameter are contained, and the surface roughness of the conductive support and the intermediate layer is controlled in a specific range, respectively (Patent Document 2 below). Patent Document 2 describes that by using such an electrophotographic photosensitive member, image defects can be reduced particularly under high temperature and high humidity or low temperature and low humidity.

JP 2002-287396 A JP 2005-338445 A

  As a method for improving the above-described density unevenness, simply increasing the electron transport property of the intermediate layer can be considered. However, simply increasing the electron transport property of the intermediate layer cannot sufficiently suppress the injection of holes from the conductive support to the photosensitive layer, that is, sufficient hole blocking properties cannot be obtained. In addition, in the case where a highly sensitive charge generation material contained in the charge generation layer is used, carrier leakage generated by thermal excitation occurs, which causes the surface potential of the electrophotographic photosensitive member to partially There is a problem that image defects such as black spots and fog occur.

  In this regard, depending on the conventional technique described in Patent Document 1, the electron transport property of the intermediate layer is lowered, and the density unevenness is not sufficiently suppressed. On the other hand, in the prior art described in Patent Document 2, the intermediate layer is thickened to increase the electron transport property and secure the hole blocking property, and reduce image defects such as density unevenness and black spots. . However, even with the conventional technique described in Patent Document 2, the density unevenness cannot be sufficiently suppressed in a recent image forming apparatus with improved detectability. Furthermore, since the semiconducting particles used in the intermediate layer have a high electron transport property, when a highly sensitive charge generation material is used in the charge generation layer, the injection of irregular electrons cannot be sufficiently suppressed, and the fogging is prevented. Such image defects are likely to occur.

  The present invention has been made based on the above circumstances, and its purpose is to suppress the occurrence of density unevenness in the formed image and to suppress the occurrence of image defects such as black spots and fog. Another object is to provide an electrophotographic photosensitive member and an image forming apparatus.

  The above object of the present invention is achieved by the following configuration.

1. On a conductive support, an electrophotographic photosensitive member intermediate layer and a photosensitive layer laminated, the intermediate layer, a first hydrophobized metal oxide particles, the first hydrophobic treated metal oxide particles an electrophotographic photosensitive member, wherein including that a low degree of hydrophobicity than a second hydrophobized metal oxide particles and a binder resin.

2. According to the above 1, wherein the difference between the hydrophobicity of the first hydrophobized metal oxide the second and hydrophobicity of the particles of hydrophobic treated metal oxide particles is 20% or more Electrophotographic photoreceptor.

3. 3. The electrophotographic photosensitive member according to 1 or 2 above, wherein the first hydrophobized metal oxide particles have a hydrophobicity of 45% or more.

4). The electrophotographic photosensitive member according to any one of the above items 1 to 3, wherein the first hydrophobized metal oxide particles and the second hydrophobized metal oxide particles are titanium oxide particles. .

  5. The photosensitive layer has a charge generation layer and a charge transport layer, and the charge generation layer comprises a Y-type titanyl phthalocyanine pigment or a mixture of a titanyl phthalocyanine pigment and a 2,3-butanediol adduct titanyl phthalocyanine pigment. The electrophotographic photosensitive member according to any one of the above items 1 to 4, wherein the electrophotographic photosensitive member is included.

  6). An image forming apparatus comprising the electrophotographic photosensitive member according to any one of 1 to 5 above.

  The electrophotographic photosensitive member of the present invention contains two kinds of metal oxide particles having different hydrophobization degrees in the intermediate layer, thereby suppressing density unevenness of the formed image and image defects such as black spots and fog. Can be suppressed over a long period of time. Further, according to the electrophotographic photosensitive member of the present invention, even when a highly sensitive substance is used as the charge generating substance, density unevenness and image defects in the obtained image can be effectively suppressed.

It is a schematic sectional drawing which shows an example of the laminated constitution of the electrophotographic photoreceptor of this invention. 1 is a schematic cross-sectional view showing an embodiment of an image forming apparatus of the present invention. It is a figure which shows the chart for the image evaluation in an Example.

  Hereinafter, the present invention will be described in detail.

<Configuration of electrophotographic photoreceptor>
(Layer structure of electrophotographic photoreceptor)
The electrophotographic photoreceptor of the present invention (hereinafter also simply referred to as a photoreceptor) is a negatively charged electrophotographic photoreceptor, having an intermediate layer on a conductive support, and a photosensitive layer laminated on the intermediate layer. It has been made.

  In the electrophotographic photoreceptor of the present invention, the photosensitive layer has a function of generating charges by exposure and a function of transporting the generated charges (holes) to the surface of the photoreceptor. The photosensitive layer may have a single layer structure in which the charge generation function and the charge transport function are performed in the same layer, or have a stacked structure in which the charge generation function and the charge transport function are performed in different layers. Also good. However, in order to suppress an increase in residual potential due to repeated use, it is preferable to have a stacked structure of a charge generation layer and a charge transport layer. In the electrophotographic photoreceptor of the present invention, a protective layer may be further formed on the photosensitive layer.

  The layer configuration of the electrophotographic photoreceptor of the present invention is not particularly limited, but specific examples include the following (1) and (2) layer configurations. That is, (1) A laminate in which an intermediate layer is provided on a conductive support, and a charge generation layer containing a charge generation material and a charge transport layer containing a charge transport material are laminated on the intermediate layer in this order. A layer structure in which a photosensitive layer having a structure is laminated, and the charge transport layer is an outermost surface layer; (2) an intermediate layer is provided on a conductive support, and a charge generating material and a charge transport material are provided on the intermediate layer. 1 is a layer structure in which a photosensitive layer having a single layer structure is laminated, and the photosensitive layer (single layer) is the outermost surface layer.

  In the present invention, it is preferable that the electrophotographic photoreceptor is constituted by an organic compound exhibiting at least one of a charge generation function and a charge transport function that are indispensable for the construction of the electrophotographic photoreceptor. The electrophotographic photosensitive member of the present invention includes a photosensitive member having a photosensitive layer composed of a known organic charge generating material or organic charge transporting material, and a photosensitive layer having a charge generating function and a charge transporting function composed of a polymer complex. All known electrophotographic photoreceptors such as a photoreceptor having

  Hereinafter, the case where the electrophotographic photosensitive member of the present invention has the preferred layer configuration (1) will be specifically described.

  FIG. 1 is a schematic sectional view showing an example of the layer structure of the electrophotographic photosensitive member of the present invention.

  In the electrophotographic photoreceptor 10, a photosensitive layer 17 is formed by laminating a charge generation layer 16 and a charge transport layer 18 in this order on an electroconductive support 12 via an intermediate layer 14.

  In the electrophotographic photoreceptor 10, when the surface of the electrophotographic photoreceptor 10 is negatively charged and then exposed, charges are generated in the charge generation layer 16. Of the charges generated in the charge generation layer 16, negative charges (electrons) move to the conductive support 12 through the intermediate layer 14, and holes move to the surface of the electrophotographic photoreceptor 10 through the charge transport layer 18. By canceling the negative charge on the surface of the electrophotographic photosensitive member 10, an electrostatic latent image is formed on the surface of the electrophotographic photosensitive member 10.

  Although not shown, the present invention is characterized in that the intermediate layer 14 includes two types of metal oxide particles having different degrees of hydrophobicity. As a result, in the intermediate layer, it is possible to ensure the electron transport property and suppress the injection of irregular electrons and holes, suppress the occurrence of image unevenness, and suppress the occurrence of image defects such as black spots and fog. .

  Next, regarding the photosensitive layer comprising the conductive support, the intermediate layer, the charge generation layer and the charge transport layer constituting the photoreceptor of the present invention, the members constituting each layer will be described.

<Conductive support>
The conductive support constituting the electrophotographic photosensitive member of the present invention may be cylindrical or sheet-like and may be any one as long as it has conductivity. For example, aluminum, copper, chromium , A metal such as nickel, zinc and stainless steel formed into a drum or sheet, a metal foil such as aluminum or copper laminated on a plastic film, a metal film deposited with aluminum, indium oxide or tin oxide, Examples thereof include metals, plastic films, and papers each having a conductive layer formed by applying a conductive substance alone or together with a binder resin.

<Intermediate layer>
In the present invention, two types of metal oxide particles having different degrees of hydrophobicity between the conductive support and the photosensitive layer, that is, the first metal oxide particles and the first metal oxide particles are more hydrophobic. An intermediate layer including the second metal oxide particles having a low degree is provided. The intermediate layer is constituted by first and second metal oxide particles and a binder resin.

  In the electrophotographic photosensitive member of the present invention, details are unknown, but by including two kinds of metal oxide particles having different degrees of hydrophobicity in the intermediate layer, the orientation between the binder resin and the metal oxide particles, That is, it is estimated that the mutual positional relationship can be controlled. As a result, while maintaining high electron transportability, charge injection from the charge generation layer and the conductive support can be suppressed, density unevenness can be suppressed, and image defects such as black spots and fog can be suppressed. Conceivable.

  When an intermediate layer is formed by mixing metal oxide particles with different degrees of hydrophobicity, the first metal oxide particles with higher degree of hydrophobicity and the second metal with lower degree of hydrophobicity due to the difference in degree of hydrophobicity It is presumed that oxide particles tend to be unevenly distributed. Metal oxide particles with a high degree of hydrophobicity form a thin layer in the intermediate layer, so that irregular electrons are injected from the charge generation layer, holes from the conductive support, and injected into the intermediate layer. It is considered that the movement of irregular charges can be effectively suppressed and image defects such as black spots and fog can be suppressed. According to the electrophotographic photosensitive member of the present invention, when a highly sensitive charge generating material is used as the charge generating material in the charge generating layer, which has been difficult to suppress in the past, other than exposure such as thermal excitation. It is possible to suppress image defects such as black spots and fog caused by carrier leakage caused by the factor. Furthermore, in most of the intermediate layer, the second metal oxide particles having a lower degree of hydrophobicity contribute to the maintenance of the electron transport property, so that it is considered that image unevenness can also be effectively suppressed. However, the above mechanism is speculative and does not limit the present invention.

  Since the effect of this invention will be acquired if both the 1st metal oxide particle and the 2nd metal oxide particle exist in an intermediate | middle layer, there is no restriction | limiting in particular in a mutual compounding ratio. However, since it is sufficient that the first metal oxide particles contributing to the blocking property are thinly present in the intermediate layer, the first metal oxide particles than the second metal oxide particles contributing to the electron transport property of the entire intermediate layer. Less is preferable. Preferably, the blend ratio of the first metal oxide particles and the second metal oxide particles is such that the first metal oxide particles: second metal oxide particles (volume ratio) are 1: 0.8 to It is 1: 2.3, More preferably, it is 1: 1.0-1: 1.7.

  In addition, the electrophotographic photoreceptor of the present invention can achieve the desired effect as long as the first and second metal oxide particles described above are included, and other metal oxide particles are present in the intermediate layer. It may be included. The other metal oxide particles are not particularly limited, and may be different from or overlapping with the first and second metal oxide particles. It may have a different function from physical particles. Specifically, the other metal oxide particles can be appropriately selected from metal oxide particles described later.

  The degree of hydrophobicity in the present invention represents a measure (%) of wettability with respect to methanol, and is determined by the following equation. In the following formula, a (ml) represents the amount of methanol required to completely wet 0.2 g of particles added to 50 ml of distilled water.

  The first metal oxide particles and the second metal oxide particles preferably have a difference in degree of hydrophobicity of 20% to 70%, more preferably 20 to 50%. When the difference in the degree of hydrophobicity is 20% or more, the orientation between the first and second metal oxide particles and the binder resin can be controlled more reliably, and the performance of each metal oxide particle alone can be further improved. Easy to demonstrate. On the other hand, when the difference is 70% or less, the region in which the dispersion state is stabilized becomes wider and contributes to productivity.

  Further, the degree of hydrophobicity of the first metal oxide particles having a higher degree of hydrophobicity is preferably 45% to 95%, more preferably 50 to 75%. When it is 45% or more, the carrier blocking property is ensured, and image defects such as fog can be effectively suppressed. On the other hand, if it is 95% or less, the surface treatment amount of the metal oxide particles can be reduced, so that the electron transport property can be ensured and density unevenness can be effectively prevented.

  Examples of the first and second metal oxide particles include titanium oxide, zinc oxide, alumina (aluminum oxide), tin oxide, antimony oxide, indium oxide, bismuth oxide, and zirconium oxide. Fine particles such as doped indium oxide, antimony-doped tin oxide and zirconium oxide can be used. These metal oxide particles can be used alone or in combination. Of these, titanium oxide and zinc oxide are more preferable, and rutile titanium oxide is more preferable.

  The first and second metal oxide particles preferably have a number average primary particle size of 5 to 100 nm, more preferably 10 to 40 nm. When the number average primary particle diameter of the metal oxide particles is within the above range, the electron transporting property is suitable and the dispersibility is not impaired, so that image defects such as black spots and fog are sufficiently generated. It is possible to suppress the occurrence of density unevenness.

  In the present invention, the number average primary particle diameter of the first and second metal oxide particles is measured as follows. That is, a TEM (transmission electron microscope) image of metal oxide particles is observed at a magnification of 100,000, and 100 particles are randomly selected as primary particles. The average diameter in the ferret direction of these primary particles is measured by image analysis, and the average value thereof is obtained as “number average primary particle diameter”.

  In order to control the degree of hydrophobicity of the metal oxide particles, the metal oxide particles can be surface-treated with a surface treatment agent. At that time, the degree of hydrophobicity of the metal oxide particles can be changed depending on the type of metal oxide particles, the type of surface treatment agent, the amount of surface treatment agent used, the conditions of the surface treatment, and the like. Typically, the hydrophobization degree can be changed relatively large by appropriately selecting the surface treatment agent and the amount of the surface treatment agent used, and the desired hydrophobization degree can be further increased by adjusting the surface treatment conditions. You can get closer. Usually, the surface treatment of the first metal oxide particles having a higher degree of hydrophobicity is performed using a surface treatment agent of an inorganic compound and then a surface treatment using a surface treatment agent of an organic compound. It is preferable. On the other hand, the surface treatment of the second metal oxide particles having a lower degree of hydrophobicity is preferably performed only with a surface treatment agent of an organic compound.

  Examples of the surface treatment agent include inorganic compounds and organic compounds, and examples of the organic compounds include reactive organic silicon compounds and organic titanium compounds. The surface treating agent may be used alone or in combination of two or more.

  Examples of the inorganic compound include alumina, silica, zirconia and hydrates thereof. Among these, the combination of alumina, silica, alumina and silica is particularly preferable because the degree of hydrophobicity of the metal oxide particles can be easily controlled. These may be used alone or in combination of two or more. In addition, as the metal oxide particles subjected to the surface treatment with the inorganic compound, commercially available products such as silica and titanium oxide particles subjected to the alumina treatment may be used. Examples of commercially available products include T-805 (manufactured by Nippon Aerosil Co., Ltd.), STT-30A, STT-65S-S (manufactured by Titanium Industry Co., Ltd.), TAF-500T, TAF-1500T (manufactured by Fuji Titanium Industry Co., Ltd.), MT- 100S, MT-100T, MT-500SA (manufactured by Teika), IT-S (manufactured by Ishihara Sangyo Co., Ltd.) and the like.

  Examples of reactive organosilicon compounds include methyltrimethoxysilane, n-butyltrimethoxysilane, n-hexyltrimethoxysilane, dimethyldimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, and 3-methacryloxypropyltrimethoxy. Alkoxy such as silane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-acryloxypropyltriethoxysilane, 2-methacryloxyethyltrimethoxysilane, 3-methacryloxybutylmethyldimethoxysilane, etc. Silane; hexamethyldisilazane, and polysiloxane compounds such as methylhydrogenpolysiloxane. Among these, 3-methacryloxypropyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, and methylhydrogenpolysiloxane are particularly preferable because the degree of hydrophobicity of the metal oxide particles can be easily controlled.

  Organic titanium compounds include alkoxy titanium (ie, titanium alkoxide), titanium polymer, titanium acylate, titanium chelate, tetrabutyl titanate, tetraoctyl titanate, isopropyl triisostearoyl titanate, isopropyl tridecyl benzene sulfonyl titanate and bis (dioctyl pyro). Phosphate) oxyacetate titanate and the like can be used. Of these, titanium acylate and titanium chelate are particularly preferable.

  The surface treatment of the metal oxide particles with the surface treatment agent can be performed by a known method, and is not particularly limited, and wet treatment or dry treatment can be employed. As a dry treatment, the metal oxide particles dispersed in a cloud shape by stirring or the like are sprayed with a hydrophobizing agent solution dissolved with alcohol or the like, or a vaporized hydrophobizing agent is brought into contact with the metal oxide particles and adhered. Can do. Further, as a surface treatment method by wet treatment, for example, a metal oxide particle is added to a solution in which a surface treatment agent is dispersed in water or an organic solvent and mixed and stirred, or the metal oxide particle is mixed in a solution. And a hydrophobic treatment agent can be dropped and adhered thereto. Moreover, you may perform a wet crushing process by a bead mill etc. in the case of a wet process. Thereafter, the obtained solution can be filtered and dried, and the obtained metal oxide particles can be annealed (baked).

  The temperature at the time of mixing and stirring during the wet treatment is preferably about 30 to 150 ° C, more preferably 40 to 60 ° C. The mixing / stirring time is preferably 0.5 to 10 hours, and more preferably 1 to 5 hours. The annealing temperature can be, for example, 100 to 220 ° C., preferably 110 to 150 ° C. The annealing treatment time is preferably 0.5 to 10 hours, more preferably 1 to 5 hours. 20-50 degreeC is preferable and the process temperature in the case of performing a wet crushing process, More preferably, it is 30-40 degreeC. The time for the wet crushing treatment is preferably 10 to 120 minutes, more preferably 30 to 70 minutes.

  In the wet surface treatment method, the amount of the surface treatment agent used varies depending on the target degree of hydrophobicity and the type of the surface treatment agent, and thus cannot be specified unconditionally. . For example, in the case of a reactive organosilicon compound, 0.1 to 20 parts by mass, more preferably 1 to 15 parts by mass can be used with respect to 100 parts by mass of the untreated metal oxide particles. In the case of an organic titanium compound, 0.1 to 20 parts by mass, more preferably 2 to 15 parts by mass can be used with respect to 100 parts by mass of the untreated metal oxide particles. The addition amount of the solvent is preferably 100 to 600 parts by mass, more preferably 200 to 500 parts by mass with respect to 100 parts by mass of the untreated metal oxide particles.

  If the amount of the surface treatment agent used is equal to or more than the above lower limit value, sufficient surface treatment can be performed on the untreated metal oxide particles, so that the hole blocking property of the intermediate layer can be maintained. The occurrence of image defects such as fog and fog can be sufficiently suppressed. On the other hand, if the amount of the surface treatment agent used is less than or equal to the above upper limit value, the surface treatment agents react with each other, so that a uniform film is not attached to the surface of the metal oxide particles, and leakage easily occurs. Can be prevented.

(Binder resin)
Examples of the binder resin constituting the intermediate layer (hereinafter also referred to as intermediate layer binder resin) include polyamide resin, vinyl chloride resin, vinyl acetate resin, casein, polyvinyl alcohol resin, polyurethane resin, nitrocellulose, and ethylene-acrylic acid. Examples thereof include copolymers and gelatin. Among these, a polyamide resin is preferable from the viewpoint of suppressing dissolution of the intermediate layer when a coating solution for forming a charge generation layer described later is applied on the intermediate layer. In addition, since the surface-treated metal oxide particles are preferably dispersed in an alcohol solvent, an alcohol-soluble polyamide resin such as a methoxymethylolated polyamide resin is more preferable.

  The thickness of the intermediate layer is preferably 0.5 to 15 μm, and more preferably 1 to 7 μm. If the thickness of the intermediate layer is 0.5 μm or more, the entire surface of the conductive support can be reliably coated, and the injection of holes from the conductive support can be sufficiently blocked. The occurrence of image defects such as fog and fog can be sufficiently suppressed. On the other hand, if the thickness of the intermediate layer is 15 μm or less, the electrical resistance is small, and sufficient electron transport properties can be obtained, so that the occurrence of density unevenness can be sufficiently suppressed.

<Photosensitive layer>
In addition to a single layer structure in which a charge generation function and a charge transport function are provided in one layer, the photosensitive layer constituting the photoconductor of the present invention has a charge generation layer (CGL) and a charge transport layer (CTL) with a photosensitive layer. A layer structure with separated functions is more preferable. As described above, the function-separated type layer structure has an advantage that it is easy to control various electrophotographic characteristics according to the purpose, in addition to being able to control the increase in residual potential with repeated use. The negatively chargeable photoreceptor has a structure in which a charge generation layer is provided on an intermediate layer and a charge transport layer is provided thereon. The positively chargeable photoreceptor is provided with a charge transport layer on an intermediate layer and a charge generation layer thereon. Take the configuration. A preferred layer structure of the photosensitive layer is a negatively chargeable photoreceptor having the function separation structure.

  In the following, as a preferred specific example of the photosensitive layer, a photosensitive layer of a function-separated negatively charged photoreceptor, that is, a photosensitive layer in which a charge generation layer and a charge transport layer are laminated will be described.

(Charge generation layer)
The charge generation layer formed in the present invention preferably contains a charge generation material and a charge generation layer binder resin. Further, those formed by applying a coating solution in which a charge generating material is dispersed in a binder resin solution are preferable.

  Charge generation materials include 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, phthalocyanine pigments, and the like. is not. Preferred is a titanyl phthalocyanine pigment. These charge generation materials can be used alone or in combination of two or more.

  The charge generation material may be selected from the above according to the sensitivity to the oscillation wavelength of the exposure light source, but a phthalocyanine pigment is preferable in order to increase the sensitivity to the oscillation wavelength of the exposure light source in the digital copying machine. As the phthalocyanine pigment, a Y-type titanyl phthalocyanine pigment, or a titanyl phthalocyanine pigment and a butanediol-added titanyl phthalocyanine pigment, particularly a 2,3-butanediol-added titanyl is used in order to increase sensitivity to an oscillation wavelength of an exposure light source, for example, a wavelength of 780 nm. It is preferable to use a mixture of phthalocyanine pigments (claim 5). These phthalocyanine pigments are included in highly sensitive charge generating materials.

  Y-type titanyl phthalocyanine has 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-rays.

  Examples of the butanediol-added titanyl phthalocyanine include 2,3-butanediol-added titanyl phthalocyanine. The structure of this 2,3-butanediol-added titanyl phthalocyanine is schematically shown in the following formula (1).

  2,3-butanediol-added titanyl phthalocyanine can take different crystal forms depending on the addition ratio of butanediol. In order to obtain good sensitivity, a crystalline type obtained by reacting 1 mol of butanediol compound with 1 mol or less of 1 mol of titanyl phthalocyanine is preferable. The 2,3-butanediol-added titanyl phthalocyanine having such a crystal form has a characteristic peak in a powder X-ray diffraction spectrum at least at a Bragg angle (2θ ± 0.2 °) of 8.3 °. This 2,3-butanediol-added titanyl phthalocyanine has peaks at 24.7 °, 25.1 °, and 26.5 ° in addition to 8.3 °.

  The butanediol-added titanyl phthalocyanine may be included alone or may be included together with the non-added titanyl phthalocyanine.

  As the charge generation material, a mixture of 2,3-butanediol-added titanyl phthalocyanine and non-added titanyl phthalocyanine can also be used. Absorbance Abs (780) at a wavelength of 780 nm and absorbance Abs (700) at a wavelength of 700 nm of the photosensitive layer obtained by conversion from a relative reflection spectrum of an electrophotographic photosensitive member provided with a photosensitive layer (charge generation layer) containing this mixture. The absorbance ratio (Abs (780) / Abs (700)) is preferably 0.8 to 1.1.

  The absorbance ratio (Abs (780) / Abs (700)) can be determined as follows.

  (1) First, a photoreceptor sample is prepared in which a photosensitive layer containing a mixture of 2,3-butanediol-added titanyl phthalocyanine and non-added titanyl phthalocyanine is formed on an aluminum support. Then, the absorption spectrum of the relative reflected light of the photoconductor sample is measured. The absorption spectrum of the reflected light can be measured using an optical film thickness measuring device “Solid Lambda Thickness” (Spectra Corp.).

That is, first, the reflection intensity of the aluminum support at each wavelength is measured as a baseline. Next, the reflection intensity of the photoreceptor sample at each wavelength is measured. A value obtained by dividing the reflection intensity of the photosensitive member sample at each wavelength by the reflection intensity of the aluminum support at each wavelength is defined as “relative reflectance (R _λ )”. Thereby, a relative reflection spectrum is obtained.

  (2) Next, the relative reflection spectrum of the obtained photoreceptor sample is converted into an absorbance spectrum by the following formula (A).

Formula (A): Absλ = −log (R _λ ) [where R _λ is a relative value obtained by dividing the reflection intensity of the photosensitive member sample at the wavelength λ by the reflection intensity of the aluminum support at the wavelength λ. Reflectance is shown. ]
(3) Next, in order to remove unevenness due to interference fringes, the absorbance spectrum data converted in (2) above is approximated to a second order polynomial in each of the wavelength region 765 to 795 nm and the wavelength region 685 to 715 nm.

  (4) Then, the absorbance Abs (780) at a wavelength of 780 nm and the absorbance Abs (700) at a wavelength of 700 nm in an approximated second order polynomial are obtained. Thereby, the absorbance ratio (Abs (780) / Abs (700)) is calculated.

  Butanediol-added titanyl phthalocyanine is obtained by conversion from the relative reflection spectrum of an electrophotographic photosensitive member having a photosensitive layer (charge generating layer) containing the butane absorbance Abs (780) at a wavelength of 780 nm and a wavelength of 700 nm. The absorbance ratio (Abs (780) / Abs (700)) to the absorbance Abs (700) is preferably 0.8 to 1.1. When the absorbance ratio (Abs (780) / Abs (700)) of the photosensitive layer containing butanediol-added titanyl phthalocyanine is within the above range, the pigment crystals are easily stabilized by an appropriate dispersion share, and the photosensitivity and the repetition Image characteristics due to exposure are stabilized.

  The absorbance ratio of the photosensitive layer containing butanediol-added titanyl phthalocyanine can be measured in the same manner as described above.

(Binder resin for charge generation layer)
As the binder resin for the charge generation layer, known resins 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. Polyvinyl butyral resin is preferable. Although there is no restriction | limiting in particular as a weight average molecular weight of binder resin, It is preferable that it is 10,000-150,000, More preferably, it is 15000-100,000.

  The mixing ratio of the charge generation material to the charge generation layer binder resin is preferably 20 to 600 parts by mass, and more preferably 50 to 500 parts by mass with respect to 100 parts by mass of the charge generation layer binder resin. If the content of the charge generation material is within the above range, sufficient charge can be generated by exposure, sufficient sensitivity of the photosensitive layer (charge generation layer) can be secured, and residual potential due to repeated use. Can be prevented.

  The thickness of the charge generation layer varies depending on the characteristics of the charge generation material, the characteristics of the binder resin, the mixing ratio, and the like, but is preferably 0.01 to 5 μm, and more preferably 0.05 to 3 μm.

(Charge transport layer)
The charge transport layer formed in the present invention preferably comprises a charge (hole) transport material and a charge transport layer binder resin. The charge transport layer is preferably formed by dissolving and coating a charge transport material in a binder resin solution.

  As the charge transport material, a known compound can be used, and examples thereof include the following. That is, triarylamine derivatives, hydrazone compounds, styryl compounds, benzidine compounds, butadiene compounds, carbazole derivatives, oxazole derivatives, oxadiazole derivatives, thiazole derivatives, thiadiazole derivatives, triazole derivatives, imidazole derivatives, imidazolone derivatives, imidazolidine derivatives, bis Imidazolidine derivatives, pyrazoline compounds, oxazolone derivatives, benzimidazole derivatives, quinazoline derivatives, benzofuran derivatives, acridine derivatives, phenazine derivatives, aminostilbene derivatives, phenylenediamine derivatives, stilbene derivatives, poly-N-vinylcarbazole, poly-1-vinylpyrene and Poly-9-vinylanthracene and the like. These compounds can be used alone or in admixture of two or more. Of these, triarylamine derivatives are preferable.

  Further, a known resin can be used as the binder resin for the charge transport layer, and examples thereof include the following. That is, polyester resin, polystyrene resin, acrylic resin, vinyl chloride resin, vinyl acetate resin, polyvinyl butyral resin, epoxy resin, polyurethane resin, phenol resin, alkyd resin, polycarbonate resin, silicone resin, melamine resin, styrene-acrylonitrile copolymer Examples thereof include a resin, a polymethacrylic ester resin, and a styrene-methacrylate copolymer resin. These may be used alone or in combination of two or more. Among these, a polycarbonate resin is preferable because the water absorption is low and the charge transport material can be dispersed well.

  The charge transport layer may contain other components such as an antioxidant as necessary.

  The content of the charge transport material is preferably 10 to 200 parts by weight and more preferably 20 to 100 parts by weight with respect to 100 parts by weight of the charge transport layer binder resin. If the content of the charge transporting material is within the above range, the charge transportability can be sufficiently secured, so that the charge generated in the charge generation layer can be sufficiently transported to the surface of the electrophotographic photosensitive member, and remains due to repeated use. An increase in potential can be prevented.

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

[Protective layer]
The electrophotographic photoreceptor of the present invention may further have a protective layer on the photosensitive layer. The protective layer plays a role of protecting the photoreceptor from the external environment and impact. When a protective layer is formed, the protective layer is preferably composed of inorganic particles and a binder resin (hereinafter referred to as “binder resin for protective layer”), and an antioxidant or a lubricant as necessary. Other components such as may be contained.

  Inorganic particles contained in the protective layer include silica, alumina, strontium titanate, zinc oxide, titanium oxide, tin oxide, antimony oxide, indium oxide, bismuth oxide, tin-doped indium oxide, antimony and tantalum-doped oxide. Particles such as tin and zirconium oxide 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 inorganic particles preferably have a number average primary particle size of 1 to 300 nm, particularly preferably 5 to 100 nm.

  The number average primary particle diameter of the inorganic particles is magnified 10,000 times 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. The obtained value.

  The binder resin for the protective layer may be 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 mentioned.

  Examples of the lubricant contained in the protective layer include resin fine powder (for example, fluorine resin, polyolefin resin, silicone resin, melamine resin, urea resin, acrylic resin, styrene resin, etc.), 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, methylphenyl silicone oil, methyl hydrogen polysiloxane, cyclic dimethylpolysiloxane, alkyl-modified silicone oil, polyether-modified silicone oil, alcohol-modified silicone oil, fluorine-modified silicone oil, amino-modified silicone Corn oil, 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, trifluorinated ethylene 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) Homopolymer resin powder such as resin powder, polypropylene resin powder, polybutene resin powder, polyhexene resin powder, copolymer resin powder such as ethylene-propylene copolymer, ethylene-butene copolymer, hexene and the like Terpolymers of these, as well as Fin-based resin powder, etc.) and the like.

  The molecular weight of the resin used as the lubricant and the particle size of the powder are appropriately selected. The particle size of the resin is particularly preferably 0.1 μm to 10 μm. In order to disperse these lubricants uniformly, a dispersant may be further added to the protective layer binder resin.

<Method for producing electrophotographic photoreceptor>
The method for producing the electrophotographic photosensitive member of the present invention is not particularly limited, and an intermediate layer, a charge generation layer and a charge transport layer, or a single photosensitive layer, and a protective layer as necessary, are formed on a conductive support. A coating solution that can constitute each layer is prepared, the coating solution is sequentially applied by a known coating method, and dried to form each layer in sequence. Specifically, as the coating method, dip coating method, spray coating method, spinner coating method, bead coating method, blade coating method, beam coating method, circular amount regulation type coating method (coating using a slide hopper type coating device) Method). The circular amount regulation type coating method is described in detail in, for example, Japanese Patent Application Laid-Open No. 58-189061.

(Formation of intermediate layer)
Although there is no restriction | limiting in particular in forming an intermediate | middle layer, For example, the following methods can be used. First, the binder resin is dissolved or dispersed in a solvent, and then the first and second metal oxide particles described above are added to the dispersion and dispersed until uniform to prepare a dispersion. Thereafter, the dispersion is allowed to stand for about a day and night, and is filtered to prepare a coating solution for forming an intermediate layer. Next, this coating solution is applied onto the conductive support by the above method and dried to form an intermediate layer.

  The binder resin concentration at the time of forming the coating solution can be appropriately selected according to the film thickness of the intermediate layer and the coating method. Preferably, it is 100-3000 mass parts of solvent with respect to 100 mass parts of binder resin, More preferably, it is 500-2000 mass parts. The total concentration of the first and second metal oxide particles is preferably 200 to 600 parts by mass, more preferably 250 to 500 parts by mass with respect to 100 parts by mass of the binder resin. The component ratio in the coating liquid is the component ratio in the formed intermediate layer.

  As a solvent that can be used for forming the intermediate layer, a solvent in which metal oxide particles are well dispersed and a binder resin such as a polyamide resin is dissolved is preferable. Specifically, with respect to the polyamide resin, alcohols having 2 to 4 carbon atoms such as ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol, t-butanol, sec-butanol and the like are preferable as the binder resin. It is preferable because good solubility and coating performance are exhibited. Further, in order to improve the storage stability and the dispersibility of the inorganic fine particles, the following cosolvent can be used in combination with the solvent. Examples of the co-solvent that can provide a preferable effect include methanol, benzyl alcohol, toluene, cyclohexanone, tetrahydrofuran, and the like.

  Examples of means for dispersing conductive fine particles and metal oxide particles include, but are not limited to, an ultrasonic disperser, a bead mill, a ball mill, a sand grinder, and a homomixer. Moreover, the coating liquid for intermediate | middle layer can prevent generation | occurrence | production of an image defect by filtering a foreign material and an aggregate before application | coating.

  As a method for drying the coating film of the coating solution for the intermediate layer, a known drying method can be appropriately selected according to the type of solvent and the film thickness to be formed, and thermal drying is particularly preferable. As drying conditions, for example, heat drying can be performed at 100 to 150 ° C. for 10 to 60 minutes.

(Formation of charge generation layer)
In order to form the charge generation layer, a coating solution is prepared by dispersing the charge generation material using a disperser in a solution in which the binder resin for charge generation layer is dissolved in a solvent. Next, it is preferable to apply the coating solution to a certain film thickness by the above-described coating method, and dry the coating film to produce a charge generation layer. Also when forming a single-layer photosensitive layer containing a charge transport material and a charge transport material, the photosensitive layer can be formed by the same method as the formation of the charge generation layer.

  The concentration of the binder resin for the charge generation layer in the charge generation layer coating solution can be appropriately selected so as to have a viscosity suitable for coating. 5000 parts by mass, more preferably 1000 to 4000 parts by mass. The concentration of the charge generation material is preferably 80 to 400 parts by mass, and more preferably 150 to 300 parts by mass with respect to 100 parts by mass of the binder resin for charge generation layer.

  Solvents for dissolving and applying the charge generation layer binder resin used for the charge generation layer include, for example, toluene, xylene, methyl ethyl ketone, cyclohexanone, cyclohexane, ethyl acetate, butyl acetate, methanol, ethanol, propanol, butanol, methyl Examples include, but are not limited to, cellosolve, ethyl cellosolve, tetrahydrofuran, 1-dioxane, 1,3-dioxolane, 4-methoxy-4-methyl-2-pentanone pyridine, and diethylamine. These organic solvents may be used alone or in combination of two or more. More preferred are methyl ethyl ketone and cyclohexanone.

  As a means for dispersing the charge generating substance, the same method as the means for dispersing the metal oxide particles in the intermediate layer can be employed. In addition, the coating liquid for the charge generation layer can prevent the occurrence of image defects by filtering foreign matters and aggregates before coating. As the coating method, the above-described method can be adopted.

(Formation of charge transport layer)
In order to form the charge transport layer, the charge transport material is dissolved in a solution in which the binder resin for charge transport layer is dissolved in a solvent to prepare a coating solution. Next, it is preferable to apply the coating liquid to a certain film thickness by the above-described coating method, and dry the coating film to produce a charge transport layer.

  The concentration of the binder resin for the charge transport layer in the charge transport layer coating solution can be appropriately selected so as to have a viscosity suitable for the above coating method. Preferably, the solvent is 100 to 1000 parts by mass, and more preferably 400 to 800 parts by mass with respect to 100 parts by mass of the binder resin for charge transport layer. The charge transport material concentration is preferably 30 to 150 parts by mass, more preferably 60 to 90 parts by mass with respect to 100 parts by mass of the binder resin.

  As a means for dispersing the charge transport material, the same method as the means for dispersing the metal oxide particles in the intermediate layer can be employed. In addition, the coating liquid for the charge transport layer can prevent the occurrence of image defects by filtering foreign matters and aggregates before coating. As the coating method, the same method as that for the intermediate layer described above can be adopted.

<Protective layer>
As a method for forming the protective layer, the same method as that for the intermediate layer can be employed. The protective layer can be formed by dispersing or dissolving the components forming the protective layer in a solvent to prepare a coating liquid, applying the coating liquid to the desired thickness by the above coating method, and drying the coating liquid. it can.

<Image forming apparatus>
The image forming apparatus of the present invention has at least the electrophotographic photosensitive member of the present invention.

  FIG. 2 is a schematic cross-sectional view showing an example of the configuration of the image forming apparatus of the present invention.

  The image forming apparatus 100 is a tandem type color image forming apparatus, and includes four sets of image forming units 110Y, 110M, 110C, and 110Bk, an endless belt-shaped intermediate transfer body unit 130, a paper feeding / conveying means 150, Fixing means 170. A document image reading device SC is arranged on the upper part of the main body of the image forming apparatus 100.

  The image forming units 110Y, 110M, 110C, and 110Bk are arranged side by side in the vertical direction. The image forming units 110Y, 110M, 110C, and 110Bk are electrophotographic photosensitive members 111Y, 111M, 111C, and 111Bk that are first image carriers, and charging units 113Y and 113Y that are sequentially arranged around the drum rotation direction. 113M, 113C, 113Bk, exposure means 115Y, 115M, 115C, 115Bk, developing means 117Y, 117M, 117C, 117Bk, and cleaning means 119Y, 119M, 119C, 119Bk. Then, yellow (Y), magenta (M), cyan (C), and black (Bk) toner images can be formed on the electrophotographic photoreceptors 111Y, 111M, 111C, and 111Bk, respectively. The image forming units 110Y, 110M, 110C, and 110Bk are configured in the same manner except that the colors of toner images formed on the electrophotographic photoreceptors 111Y, 111M, 111C, and 111Bk are different. explain.

  The electrophotographic photosensitive member 111Y is the electrophotographic photosensitive member according to the present invention, and the intermediate layer constituting the electrophotographic photosensitive member has first metal oxide particles and second second particles having different degrees of hydrophobicity. Metal oxide particles are contained.

  The charging unit 113Y is a unit that applies a uniform potential to the electrophotographic photosensitive member 111Y. In the present embodiment, a corona discharge type charger is preferably used as the charging means 113Y.

  The exposure unit 115Y performs exposure on the electrophotographic photosensitive member 111Y given a uniform potential by the charging unit 113Y based on an image signal (yellow image signal), and an electrostatic latent image corresponding to a yellow image. It has the function to form. The exposure means 115Y can be composed of an LED in which light emitting elements are arrayed in the axial direction of the electrophotographic photoreceptor 111Y and an imaging element, or a laser optical system.

  The exposure light source is preferably a semiconductor laser or light emitting diode whose oscillation wavelength is in the range of 50% or more of the maximum absorbance of the charge generating material used. For example, when a mixture of 2,3-butanediol-added titanyl phthalocyanine and non-added titanyl phthalocyanine is used as the charge generating material, the thickness is preferably 650 to 800 nm. By using these exposure light sources, the exposure dot diameter in the writing direction is narrowed to 10 to 100 μm, and digital exposure is performed on the photosensitive member, so that 600 dpi (dpi: number of dots per 2.54 cm) to 2400 dpi or more The above high-resolution electrophotographic image can be formed.

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

  The developing unit 117Y is configured to supply toner to the electrophotographic photoreceptor 111Y and develop the electrostatic latent image formed on the surface of the electrophotographic photoreceptor 111Y.

  The cleaning unit 119Y can include a roller or a blade that is in pressure contact with the surface of the electrophotographic photoreceptor 111Y.

  The endless belt-shaped intermediate transfer member unit 130 is provided so as to be in contact with the electrophotographic photosensitive members 111Y, 111M, 111C, and 111Bk. The endless belt-shaped intermediate transfer body unit 130 includes an endless belt-shaped intermediate transfer body 131 that is a second image carrier, and primary transfer rollers 133Y, 133M, and 133C disposed in contact with the endless belt-shaped intermediate transfer body 131. 133Bk and a cleaning means 135 for the endless belt-shaped intermediate transfer member 131.

  The endless belt-shaped intermediate transfer member 131 is wound around a plurality of rollers 137A, 137B, 137C, and 137D and is rotatably supported.

  In the image forming apparatus 100, the electrophotographic photosensitive member 111Y, the developing unit 117Y, the cleaning unit 119Y, and the like described above are process cartridges (image forming units) that are integrally coupled and configured to be detachable from the apparatus main body. May be. Alternatively, a process cartridge (image) in which one or more members selected from the group consisting of a charging unit 113Y, an exposure unit 115Y, a developing unit 117Y, a primary transfer roller 133Y, and a cleaning unit 119Y, and the electrophotographic photosensitive member 111Y are integrally formed. Forming unit).

  The process cartridge 200 includes a casing 201, an electrophotographic photosensitive member 111Y, a charging unit 113Y, a developing unit 117Y and a cleaning unit 119Y accommodated therein, and an endless belt-shaped intermediate transfer body unit 130. The apparatus main body is provided with support rails 203L and 203R as means for guiding the process cartridge 200 into the apparatus main body. Thereby, the process cartridge 200 can be attached to and detached from the apparatus main body. These process cartridges 200 can be a single image forming unit configured to be detachable from the apparatus main body.

  The sheet feeding / conveying means 150 is provided so that the transfer material P in the sheet feeding cassette 211 can be conveyed to the secondary transfer roller 217 via a plurality of intermediate rollers 213A, 213B, 213C, 213D and a registration roller 215.

  The fixing unit 170 fixes the color image transferred by the secondary transfer roller 217. The paper discharge roller 219 is provided so as to be able to be placed on a paper discharge tray 221 provided outside the image forming apparatus with the transfer material P subjected to fixing processing interposed therebetween.

  In the image forming apparatus 100 configured as described above, an image is formed by the image forming units 110Y, 110M, 110C, and 110Bk. Specifically, the charging means 113Y, 113M, 113C, and 113Bk charge the surface of the electrophotographic photoreceptors 111Y, 111M, 111C, and 111Bk by corona discharge to be negatively charged. Next, the surface of the electrophotographic photoreceptors 111Y, 111M, 111C, and 111Bk is exposed based on the image signal by the exposure means 115Y, 115M, 115C, and 115Bk, and an electrostatic latent image is formed. Next, toner is applied to the surface of the electrophotographic photoreceptors 111Y, 111M, 111C, and 111Bk by the developing means 117Y, 117M, 117C, and 117Bk, and developed.

  Next, primary transfer rollers (primary transfer means) 133Y, 133M, 133C, and 133Bk are brought into contact with the rotating endless belt-shaped intermediate transfer member 131. As a result, the respective color images formed on the electrophotographic photoreceptors 111Y, 111M, 111C, and 111Bk are sequentially transferred onto the rotating endless belt-shaped intermediate transfer member 131, and the color image is transferred (primary transfer). ). During the image forming process, the primary transfer roller 133Bk is always in contact with the electrophotographic photosensitive member 111Bk. On the other hand, the other primary transfer rollers 133Y, 133M, and 133C are in contact with the corresponding electrophotographic photoreceptors 111Y, 111M, and 111C, respectively, only during color image formation.

  Then, after separating the primary transfer rollers 133Y, 133M, 133C, and 133Bk and the endless belt-shaped intermediate transfer body 131, the toner remaining on the surfaces of the electrophotographic photosensitive members 111Y, 111M, 111C, and 111Bk is cleaned with the cleaning unit 119Y, Remove with 119M, 119C, 119Bk. In preparation for the next image formation, the surfaces of the electrophotographic photoreceptors 111Y, 111M, 111C, and 111Bk are neutralized by a neutralizing unit (not shown) as necessary, and then negatively charged by the charging units 113Y, 113M, 113C, and 113Bk. To charge.

  On the other hand, a transfer material P (for example, a support for carrying a final image such as plain paper or a transparent sheet) accommodated in a paper feed cassette 211 is fed by a paper feed / conveying means 150, and a plurality of intermediate rollers 213A and 213B are fed. 213C, 213D, and registration rollers 215, and then conveyed to a secondary transfer roller (secondary transfer means) 217. Then, the secondary transfer roller 217 is brought into contact with the rotating endless belt-shaped intermediate transfer body 131 to transfer the color image on the transfer material P in a lump (secondary transfer). The secondary transfer roller 217 contacts the endless belt-shaped intermediate transfer body 131 only when performing secondary transfer on the transfer material P. Thereafter, the transfer material P on which the color images are collectively transferred is separated at a portion where the curvature of the endless belt-shaped intermediate transfer body 131 is high.

  The transfer material P onto which the color images have been transferred in this way is fixed by the fixing unit 170 and then sandwiched by the paper discharge roller 219 and placed on the paper discharge tray 221 outside the apparatus. Further, after separating the transfer material P onto which the color image has been collectively transferred from the endless belt-shaped intermediate transfer body 131, the residual toner on the endless belt-shaped intermediate transfer body 131 is removed by the cleaning unit 135.

  As described above, the intermediate layer of the electrophotographic photoreceptors 111Y, 111M, 111C, and 111Bk included in the image forming apparatus 100 of the present embodiment includes the first metal oxide particles having a higher degree of hydrophobicity and the degree of hydrophobicity. Therefore, it has sufficient electron transport properties, can suppress an increase in the residual potential on the surface of the photoreceptor, and can reduce image density unevenness. Furthermore, since the intermediate layers of the electrophotographic photoreceptors 111Y, 111M, 111C, and 111Bk have high hole blocking properties, even in the electrophotographic photoreceptors 111Y, 111M, 111C, and 111Bk having a particularly sensitive charge generation layer, Injection of unnecessary holes from the conductive support and movement of unnecessary thermally excited carriers from the charge generation layer can be reduced, and image defects such as black spots and fog can be suppressed.

  Hereinafter, the present invention will be specifically described through examples and comparative examples. However, the present invention is not limited to these examples.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited only to a following example. In addition, “part” described in the following examples and comparative examples represents “part by mass”.

<Preparation of surface-treated metal oxide particles>
(Preparation of surface-treated metal oxide particles 1)
Inorganic treated titanium oxide (MT-500SA; manufactured by Teica) 500 parts by mass obtained by subjecting silica and alumina to 35 nm rutile titanium oxide, 25 parts by mass methyl hydrogen polysiloxane (MHPS), 1500 parts by mass toluene After stirring and mixing, wet crushing was performed by a bead mill at a mill residence time of 25 minutes and a temperature of 35 degrees. Toluene was separated and removed by distillation under reduced pressure from the slurry obtained by wet crushing treatment. The obtained dried product was baked with MHPS at 120 ° C. for 2 hours. Then, it grind | pulverized with the pin mill and the surface-treated metal oxide particle 1 was obtained. The degree of hydrophobicity of the particles was 70%, and the true specific gravity was 3.5.

(Preparation of surface-treated metal oxide particles 2)
In the surface-treated metal oxide particles 1, surface-treated metal oxide particles 2 were obtained in the same manner as the surface-treated metal oxide particles 1 except that the amount of MHPS was changed to 12.5 parts by mass. The degree of hydrophobicity of the particles was 55%, and the true specific gravity was 3.8.

(Preparation of surface-treated metal oxide particles 3)
In the surface-treated metal oxide particles 1, except that the 35 nm rutile titanium oxide was changed to silica and alumina treated inorganic treated titanium oxide with 35 nm rutile titanium oxide, and the amount of MHPS was changed to 15 parts by mass. In the same manner as the surface-treated metal oxide particles 1, surface-treated metal oxide particles 3 were obtained. The degree of hydrophobicity of the particles was 50%, and the true specific gravity was 3.6.

(Preparation of surface-treated metal oxide particles 4)
In the surface-treated metal oxide particles 1, surface-treated metal oxide particles 4 were obtained in the same manner as the surface-treated metal oxide particles 1 except that the amount of MHPS was changed to 10 parts by mass. The degree of hydrophobicity of the particles was 40%, and the true specific gravity was 3.9.

(Preparation of surface-treated metal oxide particles 5)
500 parts by mass of 35 nm rutile titanium oxide was stirred and mixed with 1500 parts by mass of toluene, 50 parts by mass of titanium acylate (Orgaxix TPHS; manufactured by Matsumoto Fine Chemical Co., Ltd.) was added, and the mixture was stirred at 50 degrees for 2 hours. Thereafter, toluene was distilled off under reduced pressure and baked at 120 ° C. for 2 hours. Thereby, surface-treated metal oxide particles 5 were obtained. The degree of hydrophobicity of the particles was 70%, and the true specific gravity was 3.7.

(Preparation of surface-treated metal oxide particles 6)
500 parts by mass of rutile titanium oxide having a primary particle size of 35 nm is stirred and mixed with 2000 parts of toluene, 65 parts by mass of 3-methacryloxypropyltrimethoxysilane (KBM-503; manufactured by Shin-Etsu Chemical Co., Ltd.) is added, and 50 degrees For 3 hours. Thereafter, toluene was distilled off under reduced pressure and baked at 130 ° C. for 3 hours. Thereby, surface-treated metal oxide particles 6 were obtained. The degree of hydrophobicity of the particles was 35%, and the true specific gravity was 3.9.

(Preparation of surface-treated metal oxide particles 7)
After stirring and mixing 500 parts by mass of inorganic treated titanium oxide (MT-100SA; manufactured by Teica), silica-alumina-treated 15 nm rutile titanium oxide, 25 parts by mass of MHPS, and 1300 parts by mass of toluene, a bead mill is used. Wet crushing was performed under conditions of a mill residence time of 40 minutes and a temperature of 35 degrees. Toluene was separated and removed by distillation under reduced pressure from the slurry obtained by wet crushing treatment. The obtained dried product was baked with MHPS at 120 ° C. for 2 hours. Then, it grind | pulverized with the pin mill and the surface-treated metal oxide particle 7 was obtained. The surface-treated metal oxide particles 7 had a hydrophobicity of 65% and a true specific gravity of 3.7.

(Preparation of surface-treated metal oxide particles 8)
In the surface-treated metal oxide particles 6, the surface-treated metal oxide particles 6 were treated in the same manner as the surface-treated metal oxide particles 6 except that the particle size of rutile titanium oxide was changed to 15 nm and the amount of KBM-503 was changed to 60 parts by mass. Metal oxide particles 8 were obtained. The degree of hydrophobicity of the particles was 25% and the true specific gravity was 3.5.

(Preparation of surface-treated metal oxide particles 9)
In the surface-treated metal oxide particles 8, surface-treated metal oxide particles 9 were obtained in the same manner as the surface-treated metal oxide particles 8 except that the amount of KBM-503 was changed to 40 parts by mass. The degree of hydrophobicity of the particles was 15%, and the true specific gravity was 3.4.

(Preparation of surface-treated metal oxide particles 10)
In the surface-treated metal oxide particles 8, the surface-treated metal except that KBM-503 was changed to 3-acryloxypropyltrimethoxysilane (KBM-5103; manufactured by Shin-Etsu Chemical Co., Ltd.) and the addition amount was changed to 50 parts by mass. In the same manner as the oxide particles 8, surface-treated metal oxide particles 10 were obtained. The degree of hydrophobicity of the particles was 20%, and the true specific gravity was 3.5.

(Preparation of surface-treated metal oxide particles 11)
After stirring and mixing 500 parts by mass of inorganic-treated titanium oxide (manufactured by Teika), 30 parts of anatase-type titanium oxide having a thickness of 30 nm, 40 parts by mass of MHPS, and 1800 parts by mass of toluene, the mill residence time is 60 minutes by a bead mill. Wet crushing was performed under the condition of a temperature of 35 degrees. Toluene was separated and removed by distillation under reduced pressure from the slurry obtained by wet crushing treatment. The obtained dried product was baked with MHPS at 120 ° C. for 2 hours. Then, it grind | pulverized with the pin mill and the surface-treated metal oxide particle 11 was obtained. The degree of hydrophobicity of the particles was 70%, and the true specific gravity was 3.3.

(Preparation of surface-treated metal oxide particles 12)
After stirring and mixing 500 parts by mass of zinc oxide having a primary particle size of 35 nm, 35 parts by mass of MHPS, and 1700 parts by mass of toluene, wet crushing was performed with a bead mill under conditions of a mill residence time of 40 minutes and a temperature of 35 degrees. . Toluene was separated and removed by distillation under reduced pressure from the slurry obtained by wet crushing treatment. The obtained dried product was baked with MHPS at 120 ° C. for 2 hours. Then, it grind | pulverized with the pin mill and the surface-treated metal oxide particle 12 was obtained. The degree of hydrophobicity of the particles was 65%, and the true specific gravity was 4.9.

(Preparation of surface-treated metal oxide particles 13)
500 parts by mass of zinc oxide having a primary particle size of 35 nm was stirred and mixed with 2000 parts of toluene, 65 parts by mass of KBM-503 was added, and the mixture was stirred at 50 degrees for 2 hours. Thereafter, toluene was distilled off under reduced pressure and baked at 130 ° C. for 3 hours. Thereby, surface-treated metal oxide particles 13 were obtained. The degree of hydrophobicity of the particles was 30%, and the true specific gravity was 4.8.

  The surface-treated metal oxide particles obtained as described above are summarized in Table 1 below. The degree of hydrophobicity was measured as follows.

<Method of measuring the degree of hydrophobicity>
0.2 g of particles to be measured were weighed and added to 50 ml of distilled water in a 200 ml beaker. Methanol was slowly added dropwise from a burette, the tip of which was immersed in a liquid, until the entire particles were wet (until they all settled) with slow stirring. When the amount of methanol necessary for completely wetting the particles was a (ml), the degree of hydrophobicity (%) was calculated by the following formula.

[Example 1] (Photoreceptor 1)
According to the following procedure, “Photoreceptor 1” having a laminated structure in which an intermediate layer, a charge generation layer, and a charge transport layer were sequentially formed on a conductive support was produced.

<Preparation of conductive support>
An aluminum alloy blank having a length of 362 mm was mounted on an NC lathe, and was cut with a diamond sintered tool so that the outer diameter was 59.95 mm and the surface Rz _jis was 1.2 μm.

<Preparation of Photoreceptor 1>
<Formation of intermediate layer>
100 parts by mass of the following polyamide resin (N-1) as a binder resin was added to 1700 parts by mass of a mixed solvent of ethanol / n-propyl alcohol / tetrahydrofuran (volume ratio 45/20/35), and the mixture was stirred and mixed at 20 ° C. . To this solution, 200 parts by mass of the surface-treated metal oxide particles 1 and 140 parts by mass of the surface-treated metal oxide particles 3 were added and dispersed by a bead mill with a mill residence time of 5 hours. And after leaving this solution still for a whole day and night, it filtered, and the coating liquid for intermediate | middle layers was obtained. Filtration was performed under a pressure of 50 kPa using a rigesh mesh filter (manufactured by Nippon Pole Co., Ltd.) having a nominal filtration accuracy of 5 μm as a filtration filter. The intermediate layer coating solution thus obtained was applied to the outer periphery after washing the substrate by a dip coating method and dried at 120 ° C. for 30 minutes to form an “intermediate layer” having a dry film thickness of 2 μm.

<Preparation of charge generation layer>
(Synthesis of CG-1)
Crude titanyl phthalocyanine was synthesized from 1,3-diiminoisoindoline and titanium tetra-n-butoxide. A solution in which the obtained crude titanyl phthalocyanine was dissolved in sulfuric acid was poured into water to precipitate crystals. After filtering this solution, the obtained crystals were sufficiently washed with water to obtain a wet paste product. Next, the wet paste product was frozen in a freezer, thawed again, filtered and dried to obtain amorphous titanyl phthalocyanine.

  The obtained amorphous titanyl phthalocyanine and (2R, 3R) -2,3-butanediol have an equivalent ratio of (2R, 3R) -2,3-butanediol to amorphous titanyl phthalocyanine of 0.6. As such, it was mixed in orthodichlorobenzene (ODB). The obtained mixture was heated and stirred at 60 to 70 ° C. for 6 hours. The resulting solution was allowed to stand overnight, and methanol was further added to precipitate crystals. After filtering this solution, the obtained crystal was washed with methanol to obtain a charge generating material CG-1 containing (2R, 3R) -2,3-butanediol adduct titanyl phthalocyanine.

  As a result of measuring the X-ray diffraction spectrum of the charge generation material CG-1, peaks were observed at 8.3 °, 24.7 °, 25.1 °, and 26.5 °. The obtained charge generation material CG-1 was estimated to be a mixture of a titanyl phthalocyanine, a 1: 1 adduct of (2R, 3R) -2,3-butanediol, and a titanyl phthalocyanine (non-adduct).

(Preparation of charge generation layer coating solution and formation of charge generation layer)
The following components are mixed and dispersed in a circulating ultrasonic homogenizer RUS-600TCVP (manufactured by Nippon Seiki Seisakusho Co., Ltd., 19.5 kHz, 600 W) at a circulating flow rate of 40 L / H for 0.5 hour to form a charge generation layer coating solution. Prepared. The charge generation layer coating solution was applied onto the intermediate layer by the same dip coating method as that for the intermediate layer, and then dried to form a charge generation layer having a thickness of 0.5 μm.

Charge generation material: CG-1 24 parts Polyvinyl butyral resin “ESREC BL-1” (manufactured by Sekisui Chemical Co., Ltd.) 12 parts Solvent: methyl ethyl ketone / cyclohexanone = 4/1 (V / V) 400 parts <Preparation of charge transport layer>
The following components were mixed to prepare a charge transport layer coating solution. The charge transport layer coating solution was applied on the charge generation layer by the same dip coating method as that for the intermediate layer, and then dried to form a charge transport layer having a thickness of 25 μm. Thus, an electrophotographic photosensitive member (photosensitive member 1) was obtained.

The following charge transport material 225.0 parts Polycarbonate "Z300 (Mitsubishi Gas Chemical Co., Ltd.)" 300.0 parts Antioxidant "Irganox 1010 (Nihon Ciba Geigy Co., Ltd.)" 6.0 parts Tetrahydrofuran / toluene mixture (volume ratio; 3 / 1) 2000.0 parts Silicone oil “KF-54 (manufactured by Shin-Etsu Chemical Co., Ltd.)” 1.0 part The following compounds were used as charge transport materials.

(Absorbance ratio measurement)
Using the optical film thickness measuring device Solid Lambda Thickness (manufactured by Spectra Corp.), the relative reflection spectrum of the sample for reflection spectrum measurement in which the charge generation layer is dried on an aluminum support and dried to a thickness of 0.5 μm is dried. The measurement was performed according to the following procedure.

  1) First, the reflection intensity of the aluminum support at each wavelength was measured as a baseline. Next, the reflection intensity of the photoreceptor sample at each wavelength was measured. Then, a relative reflection spectrum was obtained by setting a value obtained by dividing the reflection intensity of the photosensitive member sample at each wavelength by the reflection intensity of the aluminum support as “relative reflectance (Rλ)”.

  2) The relative reflection spectrum of the obtained photoreceptor sample was converted into an absorbance spectrum by the following formula.

Absλ = −log (Rλ)
(In the formula, Rλ represents a relative reflectance obtained by dividing the reflection intensity of the photoreceptor sample at the wavelength λ by the reflection intensity of the aluminum support at the wavelength λ).
3) Next, in order to remove irregularities due to interference fringes, the absorbance spectrum data converted in 2) was approximated to a second order polynomial in each of the wavelength region 765 to 795 nm and the wavelength region 685 to 715 nm.

  4) Absorbance Abs (780) at a wavelength of 780 nm and absorbance Abs (700) at a wavelength of 700 nm in an approximated second order polynomial were obtained, and an absorbance ratio (Abs (780) / Abs (700)) was calculated. The obtained absorbance ratio (Abs (780) / Abs (700)) was 0.99.

[Examples 2 to 11] (Photoconductors 2 to 11)
<Preparation of photoconductors 2-11>
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the surface-treated metal oxide particles contained in the intermediate layer of the photosensitive member 1 were changed as shown in Table 2.

[Example 12] (Photoreceptor 12)
<Preparation of Photoreceptor 12>
A photoconductor 12 was prepared in the same manner as in Example 4 except that the charge generation layer coating solution in the photoconductor 4 was changed as follows.

(Coating solution for 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 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 (BM-1, manufactured by Sekisui Chemical Co., Ltd.) ... 10 parts by weight Methyl ethyl ketone ... ··· 700 parts by mass Cyclohexanone ············ 300 parts by mass.

[Comparative Examples 1 to 3] (Photoconductors 13 to 15)
<Preparation of photoconductors 13 to 15>
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the surface-treated titanium oxide particles contained in the intermediate layer of the photosensitive member 1 were changed as shown in Table 2.

<Performance evaluation>
By using bizhub PRO C6501 (laser exposure, reversal development, tandem color multifunction peripheral of intermediate transfer member) manufactured by Konica Minolta Business Technologies, Inc. equipped with the electrophotographic photosensitive member obtained in Examples 1-12 and Comparative Examples 1-3. 300,000 prints were made. The surface potential and images (density unevenness, fogging) before and after printing (after printing the first and 300,000 sheets) were evaluated as follows. These evaluation results are shown in Table 2-1 and Table 2-2.

<Surface potential of electrophotographic photoreceptor>
The difference (potential fluctuation ΔVi) between the initial potential (after 0 seconds) and the potential after 30 seconds at 10 ° C. and 15% RH on the surface of the obtained electrophotographic photosensitive member was measured with an electrical property measuring device. The surface potential fluctuation was measured by repeating charging and exposure under conditions of a grid voltage of −800 V and an exposure amount of 0.5 μJ / cm ² while rotating the electrophotographic photosensitive member at 130 rpm. ΔVi was evaluated based on the following criteria.

A: 20V or less before and after printing. B: 20V or less before printing, more than 20V and 30V or less after printing. C: 20V or more but 30V or less before printing, or 20V or less before printing and 30V after printing. Super D: More than 30V before printing.

<Evaluation of image>
Using bizhub PRO C6501 (laser exposure, reversal development, intermediate transfer tandem color compound machine) manufactured by Konica Minolta Business Technologies, an image was formed at 30 ° C. and 80% RH for evaluation.

1) Density unevenness The obtained electrophotographic photosensitive member was placed at the position of black (BK). Then, the transfer current was changed from 20 μA to 100 μA, and the chart shown in FIG. 3 was output. In FIG. 3, D indicates the rotation axis direction of the electrophotographic photosensitive member. An image formed on the transfer material was visually observed using “POD gloss coat (A3 size, 100 g / m ² )” (manufactured by Oji Paper Co., Ltd.) as the transfer material. The density unevenness of the image was evaluated according to the following criteria.

A: Density unevenness is not observed even when the transfer current is 60 μA or more B: Slight density unevenness is observed when the transfer current is 60 μA or more, but there is no practical problem C: Concentration unevenness is slightly observed when the transfer current is 40 to 50 μA However, there is no problem in practical use (however, it is a problem level when forming high-quality images)
D: Even if the transfer current is less than 40 μA, the density unevenness is clearly seen, which is a problem in practical use.

2) Fog (sensory evaluation)
The obtained electrophotographic photosensitive member was placed at the position of black (BK). A transfer material “POD gloss coat (A3 size, 100 g / m ² )” (produced by Oji Paper Co., Ltd.) with no image formed thereon was prepared, and this transfer material was transported to the black position, where the grid voltage was −800V, A solid image (solid white image) was formed under the condition of developing bias of −650V. Then, the presence or absence of fog on the obtained transfer material was evaluated. Similarly, a yellow solid image was formed under the conditions of a grid voltage of −800 V and a development bias of −650 V. Then, the presence or absence of fog on the obtained transfer material was evaluated. The evaluation of the presence or absence of fog was performed based on the following criteria.

A: No fogging B: Slight fogging is observed when zoomed in, but there is no practical problem C: Slight fogging is observed visually, which is a practical problem (NG)
D: The fog is conspicuous (NG).

3) Fog (concentration evaluation)
In 2) above, the fog density of the transfer material after the plain image was formed at the part where the image was not formed was measured with a Macbeth densitometer “RD-918” (manufactured by Macbeth). Specifically, it measured by the following procedures.

  (A) The absolute image density of 20 arbitrary positions of the transfer material (white paper) on which no image was formed was measured, and the average value thereof was defined as “white paper density before image formation”.

  (B) Each of the obtained electrophotographic photosensitive members was mounted on a black (BK) image forming unit, and a solid image was formed on the transfer material of 2) above. Absolute image densities at 20 arbitrary positions of the obtained transfer material were measured, and the average value thereof was defined as “white paper density after plain image formation”.

  (C) The blank paper density obtained in the above (a) and (b) was obtained as the fog density based on the following formula (B).

Formula (B): fog density = (white paper density after plain image formation) − (white paper density before image formation)
The fog density was evaluated based on the following criteria.

A: Fog is good when fog density is 0.003 or less B: Fog is good when fog density is more than 0.003 and less than 0.006 C: Fog density is more than 0.006 and less than 0.01 Level D: The fog density is over 0.01, which is a practical problem.

  As shown in Table 2-1 and Table 2-2 above, the electrophotographic photoreceptors of Examples 1 to 12 using the first and second metal oxide particles having different degrees of hydrophobicity in the intermediate layer, It was confirmed that ΔVi of the surface potential was as low as 20 V or less before printing and 30 V or less after printing, and both density unevenness and fogging could be suppressed. On the other hand, in Comparative Example 3 using two types of metal oxide particles having the same degree of hydrophobicity, the photoreceptors 13 and 14 according to Comparative Examples 1 and 2 in which the metal oxide particles contained in the intermediate layer are one type. It was confirmed that the photoreceptor 15 cannot achieve both density unevenness and fogging.

DESCRIPTION OF SYMBOLS 10 Electrophotographic photoreceptor 12 Conductive support body 14 Intermediary layer 16 Charge generation layer 17 Photosensitive layer 18 Charge transport layer 100 Image forming apparatus 110Y, 110M, 110C, 110Bk Image forming unit 111Y, 111M, 111C, 111Bk Electrophotographic photoreceptor 113Y , 113M, 113C, 113Bk Charging means 115Y, 115M, 115C, 115Bk Exposure means 117Y, 117M, 117C, 117Bk Developing means 119Y, 119M, 119C, 119Bk Cleaning means 130 Endless belt-shaped intermediate transfer body unit 131 Endless belt-shaped intermediate transfer body 133Y, 133M, 133C, 133Bk Primary transfer roller (transfer means)
135 Cleaning means 137A, 137B, 137C, 137D Roller 150 Paper feed conveyance means 170 Fixing means 200 Process cartridge 201 Housing 203R, 203L Support rail 211 Paper feed cassette 213A, 213B, 213C, 213D Intermediate roller 215 Registration roller 217 Secondary transfer Roller (transfer means)
219 Paper discharge roller 221 Paper discharge tray D Rotational axis direction of electrophotographic photosensitive member P Transfer material SC Document image reading device

Claims (6)

In an electrophotographic photoreceptor in which an intermediate layer and a photosensitive layer are laminated on a conductive support,
The intermediate layer, a first hydrophobized metal oxide particles, the low degree of hydrophobicity than the first hydrophobized metal oxide particles a second hydrophobized metal oxide particles and including a binder resin An electrophotographic photosensitive member characterized by the above. According to claim 1, wherein the difference between the hydrophobicity of the first hydrophobized metal oxide the second and hydrophobicity of the particles of hydrophobic treated metal oxide particles is 20% or more Electrophotographic photoreceptor. The electrophotographic photosensitive member according to claim 1 or 2, wherein the first hydrophobized metal oxide particles have a hydrophobicity of 45% or more. The electrophotographic photosensitive member according to any one of claims 1 to 3, wherein the first hydrophobized metal oxide particles and the second hydrophobized metal oxide particles are titanium oxide particles. body.   The photosensitive layer has a charge generation layer and a charge transport layer, and the charge generation layer comprises a Y-type titanyl phthalocyanine pigment or a mixture of a titanyl phthalocyanine pigment and a 2,3-butanediol adduct titanyl phthalocyanine pigment. The electrophotographic photosensitive member according to claim 1, wherein the electrophotographic photosensitive member is included.   An image forming apparatus comprising the electrophotographic photosensitive member according to claim 1.