JP2007193265A - Method for manufacturing electrophotographic photoreceptor and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method by which an electrophotographic photoreceptor which suppresses exposure memory can be obtained, and an image forming apparatus capable of obtaining a high-quality image. <P>SOLUTION: In the method for manufacturing an electrophotographic photoreceptor having a photosensitive layer or a charge generating layer formed on a conductive substrate, the photosensitive layer or the charge generating layer is formed by preparing a coating liquid by agitating a mixture including at least a phthalocyanine compound, a binder resin and a solvent under a gauge pressure of >0 to 3.0 kg/cm<SP>2</SP>and by applying and drying the coating liquid on the conductive substrate. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for manufacturing an electrophotographic photoreceptor and an image forming apparatus.

  In the image forming apparatus, a charging step for charging the surface of the electrophotographic photosensitive member, an exposure step for exposing the surface of the electrophotographic photosensitive member to form an electrostatic latent image, and developing the electrostatic latent image as a toner image. The development step, the transfer step for transferring the toner image from the electrophotographic photosensitive member to the transfer target, and the charge eliminating step for removing the charge on the surface of the electrophotographic photosensitive member are repeated. Therefore, the potential (bright potential) of the portion exposed in the previous exposure process is affected, and the portion exposed in the previous exposure may not reach the desired charging potential (dark potential) even after the next charging step. is there. If exposure is performed in the next exposure step while the dark potential is low, the bright potential also decreases. This phenomenon is called exposure memory.

  The image density changes between the portion with the exposure memory and the portion without the exposure memory, and a high-quality image cannot be obtained. In particular, in an electrophotographic photosensitive member having a long electron transport distance such as a positively charged single-layer type electrophotographic photosensitive member, an exposure memory appears remarkably. This is because the mobility of the electron transport agent is smaller than that of the hole transport agent (see Patent Document 1).

Recently, in order to reduce the size of the image forming apparatus and reduce the initial cost, there is a demand for an image forming apparatus that does not have a charge removal process. However, an exposure memory appears remarkably in an image forming apparatus that does not have a charge removal process.
JP 2001-305755 A

  Accordingly, an object of the present invention is to provide a manufacturing method capable of obtaining an electrophotographic photosensitive member with a reduced exposure memory, and an image forming apparatus capable of obtaining a high-quality image.

The method for producing an electrophotographic photoreceptor of the present invention is a method for producing an electrophotographic photoreceptor in which a photosensitive layer containing a phthalocyanine compound, a charge transport agent and a binder resin is formed on a conductive substrate. agent, a mixture containing a binder resin and a solvent, beyond 0 kg / cm ² in gauge pressure with stirring at 3.0 kg / cm ² or less under pressure to prepare a coating solution, a conductive substrate on the coating solution The photosensitive layer is formed by applying to and drying.

The method for producing an electrophotographic photosensitive member of the present invention includes an electrophotographic method in which a charge generation layer containing a phthalocyanine compound and a binder resin and a charge transport layer containing a charge transport agent and a binder resin are formed on a conductive substrate. in the method for manufacturing the photoreceptor, the phthalocyanine compound, a mixture comprising a binder resin and a solvent, and stirring at 3.0 kg / cm ² or less under pressure to prepare a coating solution beyond 0 kg / cm ² in gauge pressure, The charge generation layer is formed by applying the coating solution onto a conductive substrate or a charge transport layer and drying it.

The phthalocyanine compound is preferably metal-free phthalocyanine or oxotitanyl phthalocyanine.
When the phthalocyanine compound is a metal-free phthalocyanine, the formed photosensitive layer or charge generation layer preferably satisfies the following formula (I).
A / (C · d)> 3.00 × 10 ⁴ (I)
In formula (I), A is the absorbance at 700 nm of the photosensitive layer or charge generation layer, C is the content (% by mass) of metal-free phthalocyanine in the photosensitive layer or charge generation layer, and d is the photosensitive layer. The thickness (m) of the layer or charge generation layer.

When the phthalocyanine compound is oxotitanyl phthalocyanine, the formed photosensitive layer or charge generation layer preferably satisfies the following formula (II).
A / (C · d)> 1.75 × 10 ⁴ (II)
In the formula (II), A is the absorbance of the photosensitive layer or charge generation layer at 700 nm, C is the content (% by mass) of oxotitanyl phthalocyanine in the photosensitive layer or charge generation layer, and d is the photosensitive layer. The thickness (m) of the layer or charge generation layer.

The charge transport agent contains a hole transport agent, and the difference (IP _H −IP _P ) between the ionization potential (IP _H ) of the hole transport agent and the ionization potential (IP _P ) of the phthalocyanine compound is 0.10 to 10. It is preferably 0.40 eV.

  The image forming apparatus of the present invention includes an electrophotographic photosensitive member obtained by the production method of the present invention, a charging means for charging the surface of the electrophotographic photosensitive member, and an electrostatic latent image by exposing the surface of the electrophotographic photosensitive member. A developing unit that develops the electrostatic latent image as a toner image, and a transfer unit that transfers the toner image from the electrophotographic photosensitive member to the transfer target, and the surface of the electrophotographic photosensitive member It is characterized by not having a charge eliminating means for removing the electric charge.

According to the method for producing an electrophotographic photosensitive member of the present invention, an electrophotographic photosensitive member with reduced exposure memory can be obtained.
The image forming apparatus of the present invention can obtain a high-quality image.

<Electrophotographic photoreceptor>
Examples of the electrophotographic photosensitive member include (i) a single-layer type electrophotographic photosensitive member, and (ii) a laminated type electrophotographic photosensitive member. In the present invention, a single-layer type electrophotographic photosensitive member is highly effective in suppressing exposure memory. A photographic photoreceptor is preferred, and a positively charged single layer type electrophotographic photoreceptor is particularly preferred.

(I) Single layer type electrophotographic photosensitive member:
FIG. 1 is a schematic cross-sectional view showing an example of a single layer type electrophotographic photosensitive member. The single layer type electrophotographic photoreceptor 10 includes a conductive substrate 12 and a photosensitive layer 14 provided on the conductive substrate 12.
The single-layer electrophotographic photosensitive member 10 is not limited to that shown in FIG. 1, and is within a range that does not hinder the characteristics of the single-layer electrophotographic photosensitive member 10 between the conductive substrate 12 and the photosensitive layer 14. A barrier layer may be provided, and a protective layer may be provided on the surface of the photosensitive layer 14.

(Conductive substrate)
Examples of the conductive substrate include metals such as iron, aluminum, copper, tin, platinum, silver, vanadium, molybdenum, chromium, cadmium, titanium, nickel, palladium, indium, stainless steel, and brass; Laminated plastic materials; glass coated with aluminum iodide, tin oxide, indium oxide or the like can be used.
Examples of the shape of the conductive substrate include a sheet shape and a drum shape. The shape of the conductive substrate may be appropriately determined according to the structure of the image forming apparatus.

(Photosensitive layer)
The photosensitive layer is a layer containing a charge generating agent, a charge transporting agent (a hole transporting agent and / or an electron transporting agent), and a binder resin.

  In the present invention, a phthalocyanine compound is used as a charge generator. As the phthalocyanine compound, metal-free phthalocyanine represented by the following formula (1-1) or oxotitanyl phthalocyanine represented by the following formula (1-2) is preferable in that the effect of suppressing exposure memory is high. Hereinafter, the compound represented by the formula (1-1) is referred to as a compound (1-1). Other compounds are described in the same manner.

As the compound (1-2), the following (a) and (b) are excellent in terms of storage stability in an organic solvent, stability against changes in temperature and humidity, and excellent dispersibility in an organic solvent. Those satisfying at least one of the characteristics are preferred.
(A) In the differential scanning calorimetry, the crystal does not have a temperature change peak at 50 to 400 ° C. other than the peak accompanying vaporization of adsorbed water.
(B) The crystals recovered after being immersed in an organic solvent for 24 hours have a maximum peak at least at a Bragg angle 2θ ± 0.2 ° = 27.2 ° in a CuKα characteristic X-ray diffraction spectrum; There is no peak at 2 °.

  The photosensitive layer may contain other charge generating agents. Other charge generators include perylene pigments, bisazo pigments, diketopyrrolopyrrole pigments, metal-free naphthalocyanine pigments, metal naphthalocyanine pigments, squaraine pigments, trisazo pigments, indigo pigments, azurenium pigments, cyanine pigments, pyrylium pigments , Organic photoconductors such as ansanthrone pigment, triphenylmethane pigment, selenium pigment, toluidine pigment, pyrazoline pigment, quinacridone pigment; inorganic such as selenium, selenium-tellurium, selenium-arsenic, cadmium sulfide, amorphous silicon Examples thereof include a photoconductive agent. A charge generating agent may be used individually by 1 type, and may be used in combination of 2 or more type.

  Examples of the hole transport agent include triarylamine compounds, oxadiazole compounds such as 2,5-di (4-methylaminophenyl) -1,3,4-oxadiazole, and 9- (4-diethylaminostyryl). ) Styryl compounds such as anthracene, carbazole compounds such as polyvinyl carbazole, organic polysilane compounds, pyrazoline compounds such as 1-phenyl-3- (p-dimethylaminophenyl) pyrazoline, hydrazone compounds, indole compounds, oxazole compounds Examples thereof include nitrogen-containing cyclic compounds such as compounds, isoxazole compounds, thiazole compounds, thiadiazole compounds, imidazole compounds, pyrazole compounds and triazole compounds, and condensed polycyclic compounds. A hole transport agent may be used individually by 1 type, and may be used in combination of 2 or more type.

The hole transport agent is such that the difference (IP _H −IP _P ) between the ionization potential (IP _H ) of the hole transport agent and the ionization potential (IP _P ) of the phthalocyanine compound is 0.10 to 0.40 eV. It is preferable to select. If IP _H -IP _P is within this range, the effect of suppressing the exposure memory is further increased. The ionization potential is measured using an atmospheric-type ultraviolet photoelectron analyzer (manufactured by Riken Keiki Co., Ltd., AC-1).
As the hole transport agent, compounds (2-1) to (2-7) are preferable.

As electron transport agents, quinone derivatives, anthraquinone derivatives, malononitrile derivatives, thiopyran derivatives, trinitrothioxanthone derivatives, 3,4,5,7-tetranitro-9-fluorenone derivatives, dinitroanthracene derivatives, dinitroacridine derivatives, nitroantharaquinone Derivatives, dinitroanthraquinone derivatives, tetracyanoethylene, 2,4,8-trinitrothioxanthone, dinitrobenzene, dinitroanthracene, dinitroacridine, nitroanthraquinone, dinitroanthraquinone, succinic anhydride, maleic anhydride, dibromomaleic anhydride, etc. It is done. An electron transfer agent may be used individually by 1 type, and may be used in combination of 2 or more type.
As the electron transfer agent, compounds (3-1) to (3-4) are preferable.

Examples of the binder resin include polycarbonate resins such as bisphenol Z type, bisphenol ZC type, bisphenol C type, bisphenol A type, polyarylate resin, styrene-butadiene copolymer, styrene-acrylonitrile copolymer, styrene-maleic acid. Copolymer, acrylic copolymer, styrene-acrylic acid copolymer, polyethylene resin, ethylene-vinyl acetate copolymer, chlorinated polyethylene resin, polyvinyl chloride resin, polypropylene resin, ionomer resin, vinyl chloride-vinyl acetate copolymer Polymers, alkyd resins, polyamide resins, polyurethane resins, polysulfone resins, diallyl phthalate resins, ketone resins, polyvinyl butyral resins, polyether resins, etc .; silicone resins, epoxy resins, phenol resins, Containing resins, thermosetting resins such as melamine resin, epoxy acrylate, urethane - photocurable resins such as acrylate. Binder resin may be used individually by 1 type, and may be used in combination of 2 or more type.
As the binder resin, a polycarbonate resin having a repeating unit represented by the following formula (4) (hereinafter referred to as Z-type polycarbonate resin) is preferable.

The photosensitive layer may contain known additives as long as the electrophotographic characteristics are not adversely affected. Examples of additives include antioxidants, radical scavengers, singlet quenchers, deterioration inhibitors such as ultraviolet absorbers, softeners, plasticizers, surface modifiers, extenders, thickeners, dispersion stabilizers. , Wax, acceptor, donor and the like.
In order to improve the sensitivity of the photosensitive layer, known sensitizers such as terphenyl, halonaphthoquinones, and acenaphthylene may be used in combination with the charge generator.

The content of the charge generating agent is preferably 0.1 to 50 parts by mass, and more preferably 0.5 to 30 parts by mass with respect to 100 parts by mass of the binder resin.
20-500 mass parts is preferable with respect to 100 mass parts of binder resin, and, as for content of a hole transport agent, 30-200 mass parts is more preferable.
5-100 mass parts is preferable with respect to 100 mass parts of binder resin, and, as for content of an electron transport agent, 10-80 mass parts is more preferable.
The thickness of the photosensitive layer is preferably 5 to 100 μm, more preferably 10 to 50 μm.

(Ii) Multilayer electrophotographic photoreceptor:
FIG. 2 is a schematic cross-sectional view showing an example of a laminated electrophotographic photosensitive member. The multilayer electrophotographic photosensitive member 20 includes a conductive substrate 12, a charge generation layer 24 provided on the conductive substrate 12, and a charge transport layer 26 provided on the charge generation layer 24. In the multilayer electrophotographic photoreceptor 20, the charge generation layer 24 and the charge transport layer 26 constitute a multilayer photosensitive layer.

The multilayer electrophotographic photosensitive member 20 is not limited to that shown in FIG. 2, and as shown in FIG. 3, a charge transport layer 26 is provided on the conductive substrate 12, and charge is generated on the charge transport layer 26. The layer 24 may be provided. However, since the thickness of the charge generation layer 24 is thinner than that of the charge transport layer 26, the charge transport layer 26 is preferably provided on the charge generation layer 24 from the viewpoint of protecting the charge generation layer 24.
Examples of the conductive substrate include those similar to the single-layer type electrophotographic photosensitive member.

(Charge generation layer)
The charge generation layer is a layer containing a charge generation agent and a binder resin.
When the charge transport layer contains a hole transport agent, the charge generation layer may contain an electron transport agent, and when the charge transport layer contains an electron transport agent, the charge generation layer contains a hole transport agent. You may contain.
Examples of the charge generating agent and the binder resin are the same as those of the single layer type electrophotographic photosensitive member.

The content of the charge generation agent in the charge generation layer is preferably 5 to 1000 parts by mass, more preferably 30 to 500 parts by mass with respect to 100 parts by mass of the binder resin.
The charge generation layer may contain a known additive as long as it does not adversely affect the electrophotographic characteristics. Examples of additives include antioxidants, radical scavengers, singlet quenchers, deterioration inhibitors such as ultraviolet absorbers, softeners, plasticizers, surface modifiers, extenders, thickeners, dispersion stabilizers. , Wax, acceptor, donor and the like.
The thickness of the charge generation layer is preferably from 0.01 to 5 μm, and more preferably from 0.1 to 3 μm.

(Charge transport layer)
The charge transport layer is a layer containing a hole transport agent or an electron transport agent as a charge transport agent, and a binder resin.
When a hole transporting agent is contained as a charge transporting agent, a negatively charged laminated electrophotographic photoreceptor is obtained. When an electron transporting agent is contained as the charge transporting agent, a positively charged laminated electrophotographic photoreceptor is obtained.
Examples of the hole transporting agent, the electron transporting agent, and the binder resin are the same as those of the single-layer type electrophotographic photosensitive member.

When the hole transport agent is contained in the charge transport layer, the content of the hole transport agent is preferably 10 to 500 parts by mass, and more preferably 25 to 200 parts by mass with respect to 100 parts by mass of the binder resin.
When the electron transport agent is contained in the charge transport layer, the content of the electron transport agent is preferably 5 to 200 parts by weight, and more preferably 10 to 100 parts by weight with respect to 100 parts by weight of the binder resin.
The charge transport layer may contain a known additive as long as the electrophotographic characteristics are not adversely affected. Examples of additives include antioxidants, radical scavengers, singlet quenchers, deterioration inhibitors such as ultraviolet absorbers, softeners, plasticizers, surface modifiers, extenders, thickeners, dispersion stabilizers. , Wax, acceptor, donor and the like.
The thickness of the charge transport layer is preferably 2 to 100 μm, and more preferably 5 to 50 μm.

<Method for producing electrophotographic photoreceptor>
(I) Single layer type electrophotographic photosensitive member:
A single-layer electrophotographic photosensitive member is prepared by preparing a coating solution containing a phthalocyanine compound, a charge transfer agent, a binder resin and a solvent, coating the coating solution on a conductive substrate, and drying the coating layer. Manufactured by.
The present invention is characterized in that the coating solution is prepared as follows.
A mixture containing a phthalocyanine compound, a charge transport agent, a binder resin and a solvent is stirred under a pressure of more than 0 kg / cm ² and not more than 3.0 kg / cm ² as a gauge pressure to prepare a coating solution. The gauge pressure is a pressure when the atmospheric pressure is 0 kg / cm ² .

By applying pressure at the time of preparing the coating solution, the dispersibility of the phthalocyanine compound is improved, and the effect of suppressing the exposure memory is enhanced for the reason described later. However, even if the pressure exceeds 3.0 kg / cm ² , there is not much change in the suppression effect of the exposure memory, and it is necessary to prepare a container that can sufficiently withstand the pressure, which is not economical. .
The coating solution is preferably prepared under a gauge pressure of 0.1 to 3.0 kg / cm ² .

  Pressurization and stirring of the mixture are performed using a disperser capable of pressurization. As the disperser, for example, as shown in FIG. 4, a pressure-resistant container 38 in which a pressure port 34 and an overpressure relief port 36 are provided in the lid portion 32, and a tip of a rotating shaft 42 that penetrates the lid portion 32. In addition, a disperser 30 including a stirrer 40 provided with a stirring head 46 having a plurality of slits 44 may be mentioned.

  Examples of the solvent include alcohols such as methanol, ethanol, isopropanol and butanol; aliphatic hydrocarbons such as n-hexane, octane and cyclohexane; aromatic hydrocarbons such as benzene, toluene and xylene; dichloromethane, dichloroethane, Halogenated hydrocarbons such as chloroform, carbon tetrachloride and chlorobenzene; ethers such as dimethyl ether, diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether and diethylene glycol dimethyl ether; ketones such as acetone, methyl ethyl ketone and cyclohexanone; esters such as ethyl acetate and methyl acetate Dimethylformaldehyde, dimethylformamide, dimethyl sulfoxide and the like. A solvent may be used individually by 1 type and may be used in mixture of 2 or more types.

In order to improve the dispersibility of each component and the smoothness of the surface of the photosensitive layer, a surfactant, a leveling agent and the like may be added to the coating solution.
Examples of the coating method include known methods such as a dip coating method and a blade coating method.
Examples of the drying method include known methods such as a hot air drying method and a vacuum drying method.

(Ii) Multilayer electrophotographic photoreceptor:
A multilayer electrophotographic photosensitive member is prepared by preparing a coating solution containing a phthalocyanine compound, a binder resin, and a solvent, coating the coating solution on a conductive substrate or a charge transporting layer, and drying the coating solution. Manufactured by.
The present invention is characterized in that the coating solution is prepared as follows.
A mixture containing a phthalocyanine compound, a binder resin and a solvent is stirred under a pressure of more than 0 kg / cm ² and not more than 3.0 kg / cm ² as a gauge pressure to prepare a coating solution.

By applying pressure at the time of preparing the coating solution, the dispersibility of the phthalocyanine compound is improved, and the effect of suppressing the exposure memory is enhanced for the reason described later. However, even if the pressure exceeds 3.0 kg / cm ² or less, there is not much change in the suppression effect of the exposure memory, and it is necessary to prepare a container that can sufficiently withstand the pressure. Absent.
The coating solution is preferably prepared under a gauge pressure of 0.1 to 3.0 kg / cm ² .

Examples of the disperser used for pressurization and stirring of the mixture include the same ones used for preparing the coating solution for the photosensitive layer of the single-layer type electrophotographic photosensitive member.
Examples of the solvent include the same solvents as those used for the coating solution for the photosensitive layer of the single-layer electrophotographic photosensitive member.
Examples of the coating method and the drying method include the same methods as those used when forming the photosensitive layer of the single-layer type electrophotographic photosensitive member.

For the charge transport layer, for example, a coating liquid in which a charge transport agent (hole transport agent or electron transport agent), a binder resin, or the like is dissolved or dispersed in a solvent is coated on the conductive substrate or the charge generation layer and dried. It is formed by letting.
The coating liquid is prepared by dissolving or dispersing each component in a solvent using a roll mill, a ball mill, an attritor, a paint shaker, an ultrasonic disperser or the like.
Examples of the coating method and the drying method include the same methods as those used when forming the photosensitive layer of the single-layer type electrophotographic photosensitive member.

Since more than in the manufacturing method of the electrophotographic photosensitive member of the present invention described are beyond the 0 kg / cm ² in gauge pressure with stirring at 3.0 kg / cm ² or less under pressure to prepare a coating solution The dispersibility of the phthalocyanine compound in the coating solution is improved. The dispersibility of the phthalocyanine compound is also improved in the photosensitive layer or charge generation layer obtained from the coating solution. As a result, sufficient charges are generated by exposure even near the surface of the photosensitive layer or charge generation layer, the charge transport distance is shortened, and the exposure memory is suppressed. In particular, in a positively charged single layer type electrophotographic photosensitive member, the electron transport distance is shortened, so that the effect of suppressing the exposure memory appears remarkably.

The dispersibility of the phthalocyanine compound can be determined from the absorbance of the photosensitive layer or the charge generation layer.
When the phthalocyanine compound is a metal-free phthalocyanine, if the formed photosensitive layer or charge generation layer satisfies the following formula (I), the dispersibility of the metal-free phthalocyanine is good and the exposure memory is sufficiently suppressed.
A / (C · d)> 3.00 × 10 ⁴ (I)
In formula (I), A is the absorbance at 700 nm of the photosensitive layer or charge generation layer, C is the content (% by mass) of metal-free phthalocyanine in the photosensitive layer or charge generation layer, and d is the photosensitive layer. The thickness (m) of the layer or charge generation layer.
Therefore, when the phthalocyanine compound is a metal-free phthalocyanine, the coating liquid is preferably prepared under pressure and stirring conditions that satisfy the formula (I).

When the phthalocyanine compound is oxo titanyl phthalocyanine, if the formed photosensitive layer or charge generation layer satisfies the following formula (II), the dispersibility of oxo titanyl phthalocyanine is good and the exposure memory is sufficiently suppressed.
A / (C · d)> 1.75 × 10 ⁴ (II)
In the formula (II), A is the absorbance of the photosensitive layer or charge generation layer at 700 nm, C is the content (% by mass) of oxotitanyl phthalocyanine in the photosensitive layer or charge generation layer, and d is the photosensitive layer. The thickness (m) of the layer or charge generation layer.
Therefore, the preparation of the coating solution is preferably performed under pressure and stirring conditions that satisfy the formula (II) when the phthalocyanine compound is oxotitanyl phthalocyanine.

<Image forming apparatus>
FIG. 5 is a schematic configuration diagram showing an example of the image forming apparatus of the present invention. The image forming apparatus 50 includes a charging unit 54, an exposure unit 56, a developing unit 58, and a transfer unit 60 in order along the rotation direction of the rotatable drum-shaped electrophotographic photosensitive member 52. It does not have a charge removal means for removing the surface charge.

The electrophotographic photosensitive member 52 is an electrophotographic photosensitive member obtained by the production method of the present invention.
The charging unit 54 is a unit that charges the surface of the electrophotographic photosensitive member 52.
The exposure unit 56 is a unit that exposes the surface of the electrophotographic photosensitive member 52 to form an electrostatic latent image.
The developing unit 58 is a unit that develops an electrostatic latent image as a toner image using toner. As the developing means 58, for example, a developing simultaneous cleaning type developing means that also serves as a cleaning means for removing residual toner on the surface of the electrophotographic photosensitive member 52 after toner transfer described in JP-A-2001-296742 is preferable.
The transfer unit 60 is a unit that transfers the toner image from the electrophotographic photosensitive member 52 to a transfer target (not shown).

Examples of the image forming apparatus include a copying machine, a facsimile machine, and a laser beam printer.
In the image forming apparatus of the present invention described above, since an electrophotographic photosensitive member with a reduced exposure memory is used, a memory image is not generated even if a charge eliminating unit is not provided, and a high quality image is obtained. Obtainable. Further, since there is no static elimination means, the image forming apparatus can be reduced in size, the initial cost can be reduced, and the like.

  In addition, since the image forming apparatus of the present invention uses an electrophotographic photosensitive member in which the exposure memory is suppressed, a memory image is not generated even if a developing unit using a simultaneous development cleaning system is used as the developing unit. Therefore, a high quality image can be obtained. Further, since it is not necessary to provide a cleaning unit, the image forming apparatus can be reduced in size, the initial cost can be reduced, and the like.

Each measurement and evaluation in the examples was performed as follows.
(Absorbance)
The absorbance of the photosensitive layer was measured using a spectrocolorimeter (Minolta, CM-1000). That is, the reflection absorbance (A ₁ ) with respect to light having a wavelength of 700 nm in the support substrate on which the obtained photosensitive layer (reference thickness 2.5 × 10 ⁻⁵ m) was laminated was measured with a color difference meter (manufactured by Minolta Co., Ltd., color difference). Measurement was performed using a total of CM1000). Next, the reflection absorbance (A ₂ ) with respect to light having a wavelength of 700 nm in a supporting substrate on which no photosensitive layer was laminated was measured in the same manner. Therefore, in order to eliminate the influence of the support substrate and obtain the reflection absorbance in the photosensitive layer, A ₂ which is the reflection absorbance of the support substrate is subtracted from A ₁ where the reflection absorbance of the photosensitive layer and the support substrate is mixed. The value was the absorbance of the photosensitive layer.
(thickness)
The thickness of the photosensitive layer was measured using an eddy current film thickness meter.

(Exposure memory)
An electrophotographic photosensitive member was attached to a multi-function printer (Kyocera Mita Co., Ltd. Antico40) from which the static elimination lamp was removed, and a printing test was conducted. One original as shown in FIG. 6 was printed, and then 1000 text originals (density 5%) were printed. ◎ If there is no memory image after printing the first page and 1000 pages, ◎ if there is a slight memory image ○ If either the first page or 1000 pages after printing The case where the memory image was clearly generated was evaluated as x.

[Example 1]
3 parts by mass of the compound (1-1) (IP _P 5.15 eV) as the charge generating agent, 45 parts by mass of the compound (2-1) as the hole transporting agent, 30 parts by mass of the compound (3-3) as the electron transporting agent, As a binder resin, 100 parts by mass of a Z-type polycarbonate resin (viscosity average molecular weight 20,000) and 800 parts by mass of tetrahydrofuran are placed in a disperser 30 shown in FIG. 4, and the gauge pressure is 0.10 kg / cm ² for 2 hours. The mixture was stirred to prepare a coating solution.

Next, the coating solution was applied on a conductive substrate by a dip coating method and dried with hot air at 100 ° C. for 40 minutes to form a photosensitive layer having a thickness of 25 μm, thereby obtaining a single-layer electrophotographic photosensitive member. The concentration (C) of the compound (1-1) in the photosensitive layer was 1.69% by mass.
The absorbance and thickness of the photosensitive layer were measured. In addition, the exposure memory was evaluated. The results are shown in Table 1.

[Examples 2 to 4]
A single-layer electrophotographic photosensitive member was obtained in the same manner as in Example 1 except that the coating solution was prepared under the gauge pressure shown in Table 1.
The absorbance and thickness of the photosensitive layer were measured. In addition, the exposure memory was evaluated. The results are shown in Table 1.

[Comparative Example 1]
A single-layer electrophotographic photosensitive member was obtained in the same manner as in Example 1 except that the coating solution was prepared under atmospheric pressure without applying pressure.
The absorbance and thickness of the photosensitive layer were measured. In addition, the exposure memory was evaluated. The results are shown in Table 1.

[Examples 5 to 10]
A single-layer electrophotographic photosensitive member was obtained in the same manner as in Example 3 except that the hole transporting agent was changed to compounds (2-2) to (2-7).
The absorbance and thickness of the photosensitive layer were measured. In addition, the exposure memory was evaluated. The results are shown in Table 2.

Example 11
Single-layer electrophotographic photoreceptor in the same manner as in Example 1 except that the charge generating agent was changed to Compound (1-2) (IP _P 5.25 eV) and the gauge pressure was changed to 0.20 kg / cm ^2. Got.
The absorbance and thickness of the photosensitive layer were measured. In addition, the exposure memory was evaluated. The results are shown in Table 3.

[Examples 12 to 14]
A single-layer electrophotographic photosensitive member was obtained in the same manner as in Example 11 except that the coating solution was prepared under the gauge pressure shown in Table 3.
The absorbance and thickness of the photosensitive layer were measured. In addition, the exposure memory was evaluated. The results are shown in Table 3.

[Comparative Example 2]
A single-layer electrophotographic photosensitive member was obtained in the same manner as in Example 11 except that the coating solution was prepared under atmospheric pressure without applying pressure.
The absorbance and thickness of the photosensitive layer were measured. In addition, the exposure memory was evaluated. The results are shown in Table 3.

[Examples 15 to 20]
A single-layer electrophotographic photosensitive member was obtained in the same manner as in Example 13 except that the hole transport agent was changed to compounds (2-2) to (2-7).
The absorbance and thickness of the photosensitive layer were measured. In addition, the exposure memory was evaluated. The results are shown in Table 4.

  The electrophotographic photosensitive member obtained by the production method of the present invention has a reduced exposure memory and is useful for an image forming apparatus having no charge eliminating means.

It is a schematic sectional drawing which shows an example of a single layer type electrophotographic photoreceptor. 1 is a schematic cross-sectional view showing an example of a laminated electrophotographic photoreceptor. It is a schematic sectional drawing which shows the other example of a laminated type electrophotographic photoreceptor. It is a schematic sectional drawing which shows an example of a disperser. 1 is a schematic configuration diagram illustrating an example of an image forming apparatus. It is a figure which shows the original document used for the printing test.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Single layer type electrophotographic photosensitive member 12 Conductive substrate 14 Photosensitive layer 20 Laminated type electrophotographic photosensitive member 24 Charge generation layer 50 Image forming apparatus 52 Electrophotographic photosensitive member 54 Charging means 56 Exposure means 58 Developing means 60 Transfer means

Claims (8)

In the method for producing an electrophotographic photoreceptor in which a photosensitive layer containing a phthalocyanine compound, a charge transport agent and a binder resin is formed on a conductive substrate,
Phthalocyanine compound, the charge transport material, a mixture comprising a binder resin and a solvent, and stirring at 3.0 kg / cm ² or less under pressure to prepare a coating solution beyond 0 kg / cm ² in gauge pressure,
A method for producing an electrophotographic photoreceptor, comprising forming a photosensitive layer by applying the coating solution onto a conductive substrate and drying the coating solution. In the method for producing an electrophotographic photosensitive member, wherein a charge generation layer containing a phthalocyanine compound and a binder resin and a charge transport layer containing a charge transport agent and a binder resin are formed on a conductive substrate.
A mixture containing a phthalocyanine compound, a binder resin and a solvent is stirred at a gauge pressure exceeding 0 kg / cm ² and a pressure of 3.0 kg / cm ² or less to prepare a coating solution,
A method for producing an electrophotographic photosensitive member, wherein the coating solution is applied onto a conductive substrate or a charge transport layer and dried to form a charge generation layer.   The method for producing an electrophotographic photosensitive member according to claim 1, wherein the phthalocyanine compound is a metal-free phthalocyanine. The method for producing an electrophotographic photosensitive member according to claim 3, wherein the formed photosensitive layer or charge generation layer satisfies the following formula (I).
A / (C · d)> 3.00 × 10 ⁴ (I)
In formula (I), A is the absorbance at 700 nm of the photosensitive layer or charge generation layer, C is the content (% by mass) of metal-free phthalocyanine in the photosensitive layer or charge generation layer, and d is the photosensitive layer. The thickness (m) of the layer or charge generation layer.   The method for producing an electrophotographic photosensitive member according to claim 1, wherein the phthalocyanine compound is oxotitanyl phthalocyanine. The method for producing an electrophotographic photosensitive member according to claim 5, wherein the formed photosensitive layer or charge generation layer satisfies the following formula (II).
A / (C · d)> 1.75 × 10 ⁴ (II)
In the formula (II), A is the absorbance of the photosensitive layer or charge generation layer at 700 nm, C is the content (% by mass) of oxotitanyl phthalocyanine in the photosensitive layer or charge generation layer, and d is the photosensitive layer. The thickness (m) of the layer or charge generation layer. The charge transport agent comprises a hole transport agent;
The difference (IP _H -IP _P ) between the ionization potential (IP _H ) of the hole transport agent and the ionization potential (IP _P ) of the phthalocyanine compound is 0.10 to 0.40 eV. A method for producing the electrophotographic photoreceptor according to claim 1. An electrophotographic photoreceptor obtained by the production method according to claim 1;
Charging means for charging the surface of the electrophotographic photosensitive member;
Exposure means for exposing the surface of the electrophotographic photosensitive member to form an electrostatic latent image; and
Developing means for developing the electrostatic latent image as a toner image;
A transfer means for transferring the toner image from the electrophotographic photosensitive member to the transfer target, and
An image forming apparatus having no charge eliminating means for removing electric charges on the surface of an electrophotographic photosensitive member.

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