JP2016053634A - Electrophotographic photoreceptor, manufacturing inspection method of the same and image formation device including electrophotographic photoreceptor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor and manufacturing condition of the electrophotographic photoreceptor that enable a stable high-definition image quality for a long term.SOLUTION: An electrophotographic photoreceptor has at least a laminate type photosensitive layer with an electric charge generation layer containing an electric charge generation substance and an electric charge transportation layer containing an electric transportation substance laminated in this order or a single layer type photosensitive layer containing the electric charge generation substance and the electric charge transportation substance laminated on an electric conductivity substrate. The above described problem is solved by the electrophotographic photoreceptor, in which in an integral intensity comparison by an analysis of an amount of residual solvent using thermal desorption gas chromatography, as to a residual-amount ratio A/B of a residual amount (A) of tetrahydrofuran to a residual amount (B) of 2,6-di-t-butyl-4-methylphenol, an outermost surface layer of the electrophotographic photoreceptor has a ratio A/B≤0.2.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an electrophotographic photosensitive member, a manufacturing inspection method thereof, and an image forming apparatus provided with the electrophotographic photosensitive member. More specifically, the present invention relates to an electron containing tetrahydrofuran and 2,6-di-t-butyl-4-methylphenol which is an antioxidant as a main solvent of a coating solution for forming a surface layer of a photoreceptor. The present invention relates to a photographic photoreceptor, a manufacturing inspection method thereof, and an image forming apparatus provided with an electrophotographic photoreceptor.

  In an electrophotographic image forming apparatus (hereinafter also referred to as an electrophotographic apparatus) used as a copying machine, a printer, a facsimile machine, or the like, an image is formed through the following electrophotographic process.

  First, a photosensitive layer of an electrophotographic photoreceptor (hereinafter also simply referred to as a photoreceptor) provided in the apparatus is uniformly charged to a predetermined potential by a charger. Next, exposure is performed by light such as laser light emitted from the exposure unit in accordance with image information to form an electrostatic latent image.

  The developer is supplied from the developing means to the formed electrostatic latent image, and the electrostatic latent image is developed by attaching colored fine particles called toner, which is a component of the developer, to the surface of the photoreceptor. It is visualized as a toner image. The formed toner image is transferred from the surface of the photoreceptor to a transfer material such as recording paper by a transfer unit, and fixed by a fixing unit to form an image.

However, not all the toner on the surface of the photoconductor is transferred to the recording paper and transferred during the transfer operation by the transfer means, but a part of the toner remains on the surface of the photoconductor. Further, the paper dust of the recording paper that comes into contact with the photoconductor during transfer may remain attached to the surface of the photoconductor.
Such foreign matters such as residual toner and adhering paper dust on the surface of the photosensitive member adversely affect the quality of the formed image and are removed by the cleaning device.

In recent years, cleaner-less technology has progressed, and there is also a method of removing the foreign matter by a so-called developing and cleaning system that collects residual toner by a cleaning function added to the developing unit without having an independent cleaning unit.
In this method, after the surface of the photosensitive member is cleaned, the surface of the photosensitive layer is neutralized by a static eliminator or the like, and the remaining electrostatic latent image is lost.

An electrophotographic photoreceptor used in such an electrophotographic process is configured by laminating a photosensitive layer containing a photoconductive material on a conductive substrate made of a conductive material.
Examples of electrophotographic photoreceptors include inorganic photoconductive materials and organic photoconductive materials (hereinafter referred to as organic photoconductor (OPC)). Since the sensitivity and durability of the body have been improved, organic photoreceptors are often used at present.

  In recent years, the electrophotographic photosensitive member has been mainly composed of a laminated type photosensitive member in which the photosensitive layer is functionally separated into a charge generation layer containing a charge generation material and a charge transport layer containing a charge transport material. ing. In many cases, a charge transport layer in which a charge transport material having a charge transport ability is dispersed in a molecular form in a binder resin is laminated on a charge generation layer in which a charge generation material is deposited or dispersed in a binder resin. It is a negatively charged photoreceptor.

In addition, a single-layer type photoreceptor in which a charge generation material and a charge transport material are uniformly dispersed and dissolved in the same binder resin has been proposed.
Further, in order to improve the print image quality, an undercoat layer is provided between the conductive substrate and the photosensitive layer.

  As a disadvantage of organic photoreceptors, due to the nature of organic materials, fatigue due to repeated charging, exposure, development, transfer, and other processes accumulates inside the photoreceptor, and as a result, the electrical characteristics of the photoreceptor change significantly. There is. Further, by forming a layer by dissolving or dispersing a plurality of components in a solvent, the electrical characteristics of the photoreceptor are often greatly affected by the formation process.

In particular, it has been found that residual impurities such as solvents present in the photoconductor greatly affect the electrical characteristics of the photoconductor, and this problem has been addressed. In particular, as a method for specifying the amount of solvent remaining after formation of the photoreceptor layer, a stable photosensitive layer can be formed by defining the amount of residual solvent in the layer using thermal desorption gas chromatography.
As an approach to date, there is an example in which the amount of aromatic hydrocarbon remaining in the layer is defined in the case of a photosensitive layer containing a filler (Japanese Patent Laid-Open No. 2013-142705; Patent Document 1). There is no example prescribed in the photosensitive layer not containing.

JP2013-142705A

As described above, stabilization of the electrical characteristics of the photoreceptor cannot be expected unless the amount of residual solvent in the photoreceptor is controlled.
Accordingly, an object of the present invention is to provide an electrophotographic photoreceptor having stable electrical characteristics over a long period of time by defining the residual amount of residual solvent that causes deterioration of electrical characteristics of the photoreceptor.

  As a result of intensive studies to solve the above problems, the inventor of the present invention, in an electrophotographic photoreceptor having a photosensitive layer formed on a conductive substrate, the outermost surface layer of the photoreceptor is a residual solvent tetrahydrofuran (THF). ) Is less than a certain amount with respect to 2,6-di-tert-butyl-4-methylphenol (BHT) contained as an antioxidant in THF, thereby being electrically stable. The present inventors have found that a photoreceptor can be provided, and have completed the present invention.

Thus, according to the present invention, at least a charge generation layer containing a charge generation material and a charge transport layer containing a charge transport material are laminated in this order, or a single layer containing a charge generation material and a charge transport material. An electrophotographic photosensitive member in which a mold type photosensitive layer is laminated on a conductive substrate,
The outermost surface layer of the electrophotographic photosensitive member was compared with the residual amount (B) of 2,6-di-t-butyl-4-methylphenol in the integrated intensity comparison by analyzing the residual solvent amount using thermal desorption gas chromatography. An electrophotographic photosensitive member having a ratio A / B ≦ 0.2 with respect to a residual amount ratio A / B of the residual amount (A) of tetrahydrofuran.
Is provided.

  Further, according to the present invention, there is provided the electrophotographic photosensitive member, wherein the analysis of the residual solvent amount by the thermal desorption gas chromatography is an analysis based on an integrated intensity ratio of the residual solvent amount at a thermal desorption temperature of 200 ° C. or less. .

  Further, according to the present invention, there is provided the electrophotographic photosensitive member having a ratio A / B ≦ 0.1.

  Further, according to the present invention, there is provided the electrophotographic photosensitive member, wherein the outermost surface layer has a ratio A / B ≦ 0.05.

  Further, according to the present invention, the outermost surface layer of the electrophotographic photosensitive member is formed using a coating solution for a re-exposing layer containing tetrahydrofuran as a main solvent. Is provided.

  Further, according to the present invention, there is provided the method for producing the electrophotographic photosensitive member, wherein the outermost surface layer of the photographic photosensitive member is formed by a drying step under a drying temperature condition of more than 100 ° C. and less than 150 ° C. .

  Further, the electrophotographic photosensitive member, a charging unit for charging the electrophotographic photosensitive member, an exposure unit for exposing the charged electrophotographic photosensitive member to form an electrostatic latent image, and the electrostatic latent image An image forming apparatus comprising: a developing unit that develops a toner image by developing toner; a transfer unit that transfers the toner image onto a recording material; and a fixing unit that fixes the transferred toner image onto the recording material. Is provided.

  The inventors of the present invention provide that the outermost surface layer of the electrophotographic photosensitive member according to the present invention includes a solvent for the coating solution for the outermost surface layer of the electrophotographic photosensitive member and an additive, and the ratio of the remaining amount is within a specific range. Thus, it is possible to provide an electrophotographic photosensitive member that is electrically stable for a long period of time and an image forming apparatus including the photosensitive member.

1 is a schematic cross-sectional view showing a configuration of an electrophotographic photosensitive member according to Embodiment 1 of the present invention. FIG. 5 is a schematic cross-sectional view showing a configuration of an electrophotographic photosensitive member according to Embodiment 2 of the present invention. It is a schematic cross section which shows the structure of the electrophotographic photoreceptor which concerns on Embodiment 3 of this invention. FIG. 6 is a schematic cross-sectional view showing a configuration of an image forming apparatus according to Embodiment 4 of the present invention.

  The electrophotographic photoreceptor of the present invention (hereinafter also referred to as a photoreceptor) includes a multilayer photosensitive layer in which a charge generation layer containing a charge generation material and a charge transport layer containing a charge transport material are laminated in this order, or charge generation The outermost surface layer in the electrophotographic photosensitive member in which the single-layer type photosensitive layer containing the substance and the charge transporting material is laminated on the conductive substrate contains a specific coating solution solvent and an antioxidant, and in the outermost surface layer The ratio of the residual amount of the solvent derived from the coating solution for the outermost surface layer of the previous era and its antioxidant is contained within a specific range.

  In the photoreceptor according to the present invention, a photosensitive layer is provided on a conductive substrate, and the photosensitive layer can be either a single layer type or a laminated type. Moreover, you may have a charge transport layer as an outermost surface layer, and you may provide a protective layer as an outermost layer separately. Furthermore, the charge transport layer may be composed of a first charge transport layer and a second charge transport layer, and the second charge transport layer may be the outermost surface. Moreover, it is possible to further stabilize electrically by using an undercoat layer.

  The outermost surface layer of the electrophotographic photosensitive member according to the present invention is subjected to analysis by thermal desorption chromatography, and the residual solvent amount contained in the outermost surface layer and the residual amount of the antioxidant contained in the solvent are measured. In this analysis, a section prepared by peeling and cutting off the outermost surface layer for the analysis is used as a sample.

  The outermost surface layer of the electrophotographic photosensitive member according to the present invention is the main solvent in the coating solution for the outermost surface layer in the integrated strength comparison in the analysis of the residual solvent amount by thermal desorption gas chromatography using the sample prepared from the outermost surface layer. Ratio of the residual amount A of tetrahydrofuran (THF) to the residual amount B of 2,6-di-t-butyl-4-methylphenol (butylated hydroxytoluene: BHT) as the THF-containing antioxidant used as the integral strength A / B ≦ 0.2.

The ratio of the remaining THF contained in the outermost surface layer to the BHT integrated intensity is preferably the ratio A / B ≦ 0.1, and more preferably the ratio A / B ≦ 0.05.
The drying conditions at the time of forming the outermost surface layer of the electrophotographic photoreceptor according to the present invention are such that the drying process temperature conditions in the production of the photoreceptor such that the ratio A / B by the integral intensity of THF to BHT is greater than 0.2. This is not preferable because it causes deterioration of the electrical characteristics of the body.

  When the ratio A / B is greater than 0.2, when the drying is performed at a relatively low temperature (for example, a temperature of 100 ° C. or less), and when the drying time at the same temperature is short, the amount of residual THF is large. As a result, the electrical characteristics of the photoreceptor are significantly deteriorated. Conversely, when heat treatment is performed under relatively high temperature heat treatment conditions (for example, a temperature of 150 ° C. or higher), the residual amount of THF becomes a constant value, and the decrease in the residual amount of BHT becomes remarkable. At this time, thermal deterioration of the charge transporting material, which is a constituent component, occurs, and the electrical characteristics of the photoreceptor are also deteriorated.

Although details are not clear, the reason why a correlation is obtained between the regulation of the ratio of the remaining amount of THF and the remaining amount of BHT in the surface layer of the photoreceptor according to the present invention and the stability of the electrical characteristics of the photoreceptor is as follows. Such a thing can be considered.
That is, in the case of a photosensitive layer obtained by drying at a relatively low temperature, that is, at a temperature of 100 ° C. or less, volatilizable THF still remains on the surface of the photoconductor. The characteristics are determined.
On the other hand, in the case of a photoreceptor obtained by drying at a relatively high temperature, that is, a temperature of 150 ° C. or higher, the residual amount of THF has already converged to a constant value, but a decreasing tendency of the residual BHT amount starts. Under the heat treatment conditions, it is considered that thermal deterioration of the entire photoconductor occurs and the electrical characteristics of the photoconductor deteriorate.

  Moreover, it is preferable that the thermal desorption temperature which implements the thermal desorption chromatography contained in this invention is 200 degrees C or less. This is a temperature that is clearly lower than the melting point of BHT (265 ° C.) and does not cause decomposition of polycarbonate as a structural material, and is selected as a temperature that does not cause a significant change in the structure of the photoreceptor.

  The image forming apparatus of the present invention includes the electrophotographic photosensitive member, a charging unit that charges the electrophotographic photosensitive member, and an exposure unit that exposes the charged electrophotographic photosensitive member to form an electrostatic latent image. Developing means for developing the electrostatic latent image with toner to form a toner image; transfer means for transferring the toner image onto the recording material; and fixing the transferred toner image onto the recording material. The image forming apparatus further includes a fixing unit, and further includes a cleaning unit that removes and collects toner remaining on the electrophotographic photosensitive member, and a neutralizing unit that neutralizes surface charges remaining on the electrophotographic photosensitive member. Also good. The image forming apparatus of the present invention may be configured to include the electrophotographic photosensitive member, a charging unit, an exposure unit, a developing unit, and a transfer unit.

  Hereinafter, embodiments and examples of the present invention will be described in detail with reference to FIGS. The embodiments and examples described below are merely specific examples of the present invention, and the present invention is not limited to these.

Embodiment 1
FIG. 1 is a schematic cross-sectional view showing the configuration of the electrophotographic photoreceptor according to the first exemplary embodiment of the present invention.
The electrophotographic photoreceptor 1 according to the first embodiment (hereinafter also referred to as the photoreceptor 1) contains an undercoat layer 15 and a charge generation material on a cylindrical conductive substrate 11 made of a conductive material. The photoconductive layer 14 is composed of a photosensitive layer 14 in which a charge generation layer 12 and a charge transport layer 13 containing a charge transport material are laminated in this order.

Conductive Substrate The conductive substrate 11 functions as an electrode of the photoreceptor 1 and also functions as a support member for the layers disposed thereon, that is, the undercoat layer 15 and the photosensitive layer 14.
In addition, although the shape of the electroconductive base | substrate 11 is cylindrical shape in this Embodiment 1, it is not limited to this, A column shape, a sheet form, or an endless belt shape etc. may be sufficient.

  Examples of the conductive material constituting the conductive substrate 11 include conductive metals such as aluminum, copper, brass, zinc, nickel, stainless steel, chromium, molybdenum, vanadium, indium, titanium, gold, and platinum; or aluminum alloys And metal oxides such as tin oxide and indium oxide can be used.

Also, without being limited to these metal materials, a polymer material such as polyethylene terephthalate, nylon, polyester, polyoxymethylene or polystyrene, a laminate of the metal foil on the surface of hard paper or glass; It is also possible to use a vapor-deposited material or a material obtained by vapor-depositing or applying a conductive compound layer such as a conductive polymer, tin oxide, or indium oxide.
These conductive materials are used after being processed into a predetermined shape.

  If necessary, the surface of the conductive substrate 11 is irregularly reflected within a range that does not affect the image quality, such as anodic oxide film treatment, surface treatment with chemicals or hot water, coloring treatment, or roughening the surface. Processing may be performed.

In an electrophotographic process using a laser as an exposure light source, the wavelengths of the laser light are uniform, so the laser light reflected on the surface of the photoconductor and the laser light reflected inside the photoconductor cause interference, and the interference due to this interference occurs. Stripes may appear on the image and cause image defects.
However, by performing the above-described treatment on the surface of the conductive substrate 11, image defects due to interference of laser light having the same wavelength can be prevented.

Undercoat layer 15 (also referred to as an intermediate layer)
When the undercoat layer 15 is not provided between the conductive substrate 11 and the photosensitive layer 14, the chargeability is reduced in a minute region due to defects in the conductive substrate 11 or the photosensitive layer 14, and black spots or the like are caused. Image fogging may occur, resulting in significant image defects. By providing the undercoat layer 15, injection of charges from the conductive substrate 11 to the photosensitive layer 14 can be prevented.

  Therefore, the provision of the undercoat layer 15 can prevent the chargeability of the photosensitive layer 14 from being lowered, suppress the reduction of the surface charge other than the portion to be erased by exposure, and cause defects such as fogging on the image. Can be prevented.

Further, by providing the undercoat layer 15, it is possible to cover the unevenness of the surface of the conductive substrate 11 to obtain a uniform surface, so that the film formability of the photosensitive layer 14 is improved and the conductive substrate 11 of the photosensitive layer 14 is improved. Can be prevented from being peeled off, and the adhesion between the conductive substrate 11 and the photosensitive layer 14 can be improved.
For the undercoat layer 15, a resin layer or an alumite layer made of various resin materials is used.

  The resin material constituting the resin layer as the undercoat layer 15 includes polyethylene resin, polypropylene resin, polystyrene resin, acrylic resin, vinyl chloride resin, vinyl acetate resin, polyurethane resin, epoxy resin, polyester resin, melamine resin, and silicone resin. And resins such as polyvinyl butyral resin, polyvinyl pyrrolidone resin, polyacrylamide resin and polyamide resin, and copolymer resins containing two or more repeating units constituting these resins.

  Further, casein, gelatin, polyvinyl alcohol, cellulose, nitrocellulose, ethylcellulose and the like are also included.

Among these resins, it is preferable to use a polyamide resin, and it is particularly preferable to use an alcohol-soluble nylon resin.
Preferred alcohol-soluble nylon resins include so-called nylons such as 6-nylon, 6,6-nylon, 6,10-nylon, 11-nylon, 2-nylon and 12-nylon, and N-alkoxymethyl-modified nylon and Examples thereof include resins obtained by chemically modifying nylon such as N-alkoxyethyl-modified nylon.

  In order to give the undercoat layer a charge adjusting function, a filler which is metal oxide fine particles is added. Examples of such a filler include particles of titanium oxide, aluminum oxide, aluminum hydroxide, tin oxide and the like. The particle diameter of the metal oxide is suitably about 0.01 to 0.3 μm, preferably about 0.02 to 0.1 μm.

The undercoat layer 15 is formed by, for example, preparing an intermediate layer coating solution by dissolving or dispersing the above resin in an appropriate solvent and coating the coating solution on the surface of the conductive substrate 11. .
When the undercoat layer 15 contains particles such as the metal oxide fine particles, the metal oxide fine particles such as titanium oxide are dispersed in a resin solution obtained by dissolving the resin in an appropriate solvent. The undercoat layer 15 can be formed by preparing an undercoat layer coating solution and applying the coating solution to the surface of the conductive substrate 11.

As the solvent for the coating solution for the undercoat layer, water, various organic solvents, or a mixed solvent thereof is used. For example, water or alcohol such as methanol, ethanol or butanol alone, or water and alcohol, a mixture of two or more alcohols, acetone or dioxolane and alcohol, halogen organic solvents such as dichloroethane, chloroform or trichloroethane and alcohol, etc. A mixed solvent is used.
Among these solvents, non-halogen organic solvents are preferably used in consideration of the global environment.

As a method for dispersing the particles in the resin solution, a general dispersion method using a ball mill, a sand mill, an attritor, a vibration mill, an ultrasonic disperser, a paint shaker, or the like can be used.
In addition, a more stable dispersion coating liquid can be produced by using a medialess type dispersion apparatus that uses a very strong shearing force generated by passing the dispersion liquid through a micro gap at an ultrahigh pressure. It becomes possible.

Examples of the coating method for the coating solution for the undercoat layer include a spray method, a bar coating method, a roll coating method, a blade method, a ring method, and a dip coating method.
Among these coating methods, in particular, the dip coating method is a method of forming a layer on the surface of the substrate by immersing the substrate in a coating tank filled with a coating solution and then pulling it up at a constant speed or a speed that changes sequentially. Since it is relatively simple and excellent in terms of productivity and cost, it is widely used in the production of electrophotographic photosensitive members. In addition, in order to stabilize the dispersibility of a coating liquid, the apparatus used for the dip coating method may be provided with a coating liquid dispersing apparatus represented by an ultrasonic generator.

The thickness of the undercoat layer 15 is preferably 0.01 to 20 μm, more preferably 0.05 to 10 μm.
If the thickness of the undercoat layer 15 is less than 0.01 μm, it is not possible to obtain a uniform surface by covering the unevenness of the conductive substrate 11, so that the undercoat layer 15 does not substantially function as the undercoat layer 15. This is not preferable because the injection of charges from the substrate 11 to the photosensitive layer 14 cannot be prevented and the chargeability of the photosensitive layer 14 is lowered.

On the other hand, if the thickness of the undercoat layer 15 is larger than 20 μm, it becomes difficult to form the undercoat layer 15 by the dip coating method, and the photosensitive layer 14 cannot be uniformly formed on the undercoat layer 15. This is not preferable because the sensitivity of is reduced.
Therefore, a preferable range of the film thickness of the undercoat layer 15 is preferably 0.01 to 20 μm.

Charge generation layer 12
The charge generation layer 12 contains, as a main component, a charge generation material that generates charges by absorbing light.
Examples of the charge generating substance include an organic photoconductive material containing an organic pigment and an inorganic photoconductive material containing an inorganic pigment.

Examples of the organic photoconductive materials include azo pigments such as monoazo pigments, bisazo pigments and trisazo pigments, indigo pigments such as indigo and thioindigo, perylene pigments such as peryleneimide and perylene anhydride, anthraquinone and Examples include organic photoconductive materials such as polycyclic quinone pigments such as pyrenequinone, phthalocyanine pigments such as metal phthalocyanine and metal-free phthalocyanine, squarylium dyes, pyrylium salts and thiopyrylium salts, and triphenylmethane dyes.
Examples of the inorganic photoconductive material include selenium and its alloys, arsenic-selenium, cadmium sulfide, zinc oxide, amorphous silicon, and other inorganic photoconductors.

  Charge generation materials include triphenylmethane dyes typified by methyl violet, crystal violet, knight blue and victoria blue, erythrosine, rhodamine B, rhodamine 3R, acridine dyes typified by acridine orange and frapeosin, methylene blue and methylene They may be used in combination with sensitizing dyes such as thiazine dyes typified by green, oxazine dyes typified by capri blue and meldra blue, cyanine dyes, styryl dyes, pyrylium salt dyes or thiopyrylium salt dyes.

As a method of forming the charge generation layer 12, the charge generation material is vacuum-deposited on the surface of the conductive substrate 11, or the charge generation layer is obtained by dispersing the charge generation material in a suitable solvent. A method of applying the liquid to the surface of the conductive substrate 11 is used.
Among these, in a binder resin solution obtained by mixing a binder resin as a binder in a solvent, a charge generating material is dispersed by a conventionally known method to prepare a coating solution for a charge generating layer, A method of applying the obtained coating solution to the surface of the conductive substrate 11 is preferably used. Hereinafter, this method will be described.

  Examples of the binder resin used for the charge generation layer 12 include polyester resin, polystyrene resin, polyurethane resin, phenol resin, alkyd resin, melamine resin, epoxy resin, silicone resin, acrylic resin, methacrylic resin, polycarbonate resin, and polyarylate resin. And resins such as phenoxy resin, polyvinyl butyral resin, polyvinyl chloride resin and polyvinyl formal resin, and copolymer resins containing two or more of the repeating units constituting these resins.

Specific examples of the copolymer resin include insulating resins such as vinyl chloride-vinyl acetate copolymer resin, vinyl chloride-vinyl acetate-maleic anhydride copolymer resin, and acrylonitrile-styrene copolymer resin. be able to.
The binder resin is not limited to these, and a commonly used resin can be used as the binder resin. One kind of these resins may be used alone, or two or more kinds thereof may be mixed and used.

  Examples of the solvent of the coating solution for the charge generation layer include halogenated hydrocarbons such as dichloromethane or dichloroethane, alcohols such as methanol and ethanol, ketones such as acetone, methyl ethyl ketone and cyclohexanone, esters such as ethyl acetate and butyl acetate, Ethers such as tetrahydrofuran or dioxane, alkyl ethers of ethylene glycol such as 1,2-dimethoxyethane, aromatic hydrocarbons such as benzene, toluene or xylene, or N, N-dimethylformamide or N, N-dimethylacetamide An aprotic polar solvent such as is used.

  Among the above solvents, non-halogen organic solvents are preferably used in consideration of the global environment. As for said solvent, 1 type may be used independently and may be used as 2 or more types of mixed solvents.

In the charge generation layer 12 configured to include the charge generation material and the binder resin, the ratio W1 / W2 between the weight W1 of the charge generation material and the weight W2 of the binder resin is 10/100 to 400/100. It is preferable.
When the ratio W1 / W2 is less than 10/100, the sensitivity of the photoreceptor 1 is likely to be lowered.

On the other hand, when the ratio W1 / W2 exceeds 400/100, not only the film strength of the charge generation layer 12 decreases, but also the dispersibility of the charge generation material decreases and coarse particles increase. The surface charge other than the portion to be reduced is reduced, and the image defects, particularly the fogging of the image called black spots where the toner adheres to the white background and minute black spots are formed increases.
Therefore, the preferable range of the ratio W1 / W2 is preferably 10/100 to 400/100.

The charge generation material may be pulverized in advance by a pulverizer before being dispersed in the binder resin solution.
Examples of the pulverizer used for the pulverization treatment include a ball mill, a sand mill, an attritor, a vibration mill, and an ultrasonic disperser.
In addition, examples of the disperser used when the charge generating substance is dispersed in the binder resin solution include a paint shaker, a ball mill, and a sand mill. As a dispersion condition at this time, an appropriate condition can be selected so that impurities are not mixed due to wear of the container used and the members constituting the disperser.

Examples of the coating method for the charge generation layer coating liquid include a spray method, a bar coating method, a roll coating method, a blade method, a ring method, and a dip coating method.
Among these application methods, an optimum method can be selected in consideration of the physical properties and productivity of the application.
Among these coating methods, the dip coating method described in the undercoat layer coating method is particularly preferable.

The film thickness of the charge generation layer 12 is preferably 0.05 to 5 μm, more preferably 0.1 to 1 μm.
When the thickness of the charge generation layer 12 is less than 0.05 μm, the charge generation efficiency due to light absorption decreases, and the sensitivity of the photoreceptor 1 decreases.
On the contrary, if the film thickness of the charge generation layer 12 exceeds 5 μm, the light absorption efficiency is lowered, and charge transfer within the charge generation layer 12 becomes a rate-limiting step in the process of erasing the surface charge of the photosensitive layer 14. As a result, the sensitivity of the photoreceptor 1 is lowered.
Therefore, the preferable range of the film thickness of the charge generation layer 12 is preferably 0.05 to 5 μm.

Charge transport layer 13
A charge transport layer 13 is provided on the charge generation layer 12. The charge transport layer 13 is configured to include a charge transport material that receives and transports a charge generated by the charge generation material contained in the charge generation layer 12, and a binder resin that binds the charge transport material.

  The above charge transport materials include enamine derivatives, carbazole derivatives, oxazole derivatives, oxadiazole derivatives, thiazole derivatives, thiadiazole derivatives, triazole derivatives, imidazole derivatives, imidazolone derivatives, imidazolidine derivatives, bisimidazolidine derivatives, styryl compounds, hydrazones. Compound, polycyclic aromatic compound, indole derivative, pyrazoline derivative, oxazolone derivative, benzimidazole derivative, quinazoline derivative, benzofuran derivative, acridine derivative, phenazine derivative, aminostilbene derivative, triarylamine derivative, triarylmethane derivative, phenylenediamine derivative And stilbene derivatives and benzidine derivatives.

As the binder resin constituting the charge transport layer 13, a resin mainly composed of polycarbonate, which is well known in the art, is suitably selected for the reason of excellent transparency and printing durability.
In addition, as the second component, for example, a vinyl polymer resin such as polymethyl methacrylate resin, polystyrene resin, and polyvinyl chloride resin, and a copolymer resin containing two or more of repeating units constituting these, and a polyester resin Polyester carbonate resin, polysulfone resin, phenoxy resin, epoxy resin, silicone resin, polyarylate resin, polyamide resin, polyether resin, polyurethane resin, polyacrylamide resin, and phenol resin.

Moreover, the thermosetting resin which partially bridge | crosslinked these resin is also mentioned.
These resins may be used alone, or a mixture of two or more kinds may be used.
In addition, said main component means that weight% of polycarbonate resin occupies the highest ratio in the total binder resin which comprises a charge transport layer, More preferably, it is the range of 50 to 90 weight%. Means that.

The resin as the second component can be used in the range of 10 to 50% by weight in the total binder resin.
Further, the ratio of the charge transport material and the binder resin in the charge transport layer is preferably in the range of 10/18 to 10/10 in weight ratio.

When the charge transport layer 13 is the outermost layer of the photoreceptor, filler particles can be added for the purpose of improving the wear resistance of the transport layer.
The filler particles are roughly classified into organic filler particles and inorganic filler particles centered on metal oxides.
From the viewpoint of mechanical properties for improving the wear resistance of the charge transport layer 13, it is often advantageous to use a metal oxide having a relatively high hardness as the filler particles.

However, when filler particles are added to the charge transport layer 13, the following requirements are required for the filler particles, such as not impairing the electrical characteristics of the charge transport layer 13.
That is, when filler particles having a relative dielectric constant within the charge transport layer 13 that is significantly larger than the average relative dielectric constant (εr) of the organic photoreceptor (εr> 10) (for example, εr> 10) are used, It is considered that the dielectric constant becomes non-uniform and the electrical characteristics are adversely affected.

Therefore, it is considered that filler particles having a relatively low relative dielectric constant can be suitably used for the charge transport layer without causing a great adverse effect on the electrical characteristics of the charge transport layer.
Accordingly, as filler particles added to the charge transport layer 13, organic filler particles are generally more advantageous than metal oxides having a high relative dielectric constant.
In addition, when the purpose is to impart lubricity to the outermost layer of the photoreceptor, selection of a material such as fluorine fine particles is advantageous.

  Further, in order to minimize the adverse effects on light scattering and electrical carriers in the charge transport layer 13, it is preferable to use a filler having a small particle diameter. Specifically, filler particles having a median diameter (D50) of primary particles of 0.1 to 2 μm are preferable from the viewpoint of dispersion stability of a coating liquid containing the filler particles.

The addition amount of the filler particles is 1 to 40 wt%, preferably 1.5 to 35 wt%, based on the total weight of the charge transport material and the binder resin (solid content of the charge transport layer).
When the added amount of the filler particles is less than 1 wt%, the function as a filler is not achieved and the printing durability is not improved.
On the other hand, if it exceeds 40 wt%, the electrical characteristics as a photoconductor deteriorate due to the addition of insulating filler fine particles, a sufficient image density cannot be obtained, image quality defects occur, and there is a problem in practical use. It becomes.

As a method for dispersing the filler particles, a general method using a ball mill, a sand mill, an attritor, a vibration mill, an ultrasonic disperser, a paint shaker, or the like can be used in the same manner as the oxide fine particles added to the undercoat layer. .
It is also possible to produce a more stable dispersion coating liquid by using a medialess type dispersion apparatus that uses a very strong shearing force generated by passing the dispersion liquid through a micro gap at an ultrahigh pressure. it can.

  In addition, various additives may be added to the charge transport layer 13 as necessary. That is, a plasticizer or a leveling agent may be added to the charge transport layer 13 in order to improve the film formability, flexibility, or surface smoothness.

Examples of the plasticizer include dibasic acid esters such as phthalate esters, fatty acid esters, phosphate esters, chlorinated paraffins, and epoxy type plasticizers.
Moreover, as said leveling agent, a silicone type leveling agent etc. can be mentioned, for example.

  As in the case of forming the charge generation layer 12 by coating, the charge transport layer 13 is, for example, a charge transport material, a binder resin, the filler particles, and, if necessary, the additive in an appropriate solvent. The charge transport layer coating solution is prepared by dissolving or dispersing, and the resulting coating solution is applied onto the charge generation layer 12.

  As the solvent for the coating solution for the charge transport layer, generally, for example, aromatic hydrocarbons such as benzene, toluene, xylene and monochlorobenzene, halogenated hydrocarbons such as dichloromethane and dichloroethane, tetrahydrofuran, dioxane and dimethoxymethyl ether, etc. And aprotic polar solvents such as N, N-dimethylformamide. These solvents may be used alone or in combination of two or more.

In addition, a solvent such as alcohols, acetonitrile or methyl ethyl ketone may be further added to the above solvent as necessary.
Among these solvents, non-halogen organic solvents are preferably used in consideration of the global environment.

  Among them, in the present invention, tetrahydrofuran (THF) is used as the main solvent of the charge transport layer coating solution. However, THF usually contains 0.05 wt% 2,6-di-tert-butyl-4-methylphenol (BHT) as an antioxidant in the solvent, and the relative residual amount of THF and BHT. The characteristics of the photoreceptor are defined by the ratio.

  Thermal desorption gas chromatography is generally a widely used method for extracting and separating volatile and semi-volatile compounds from various matrices. In the present invention, from the matrix of the photoreceptor layer, the surface layer of the photoreceptor that leads to deterioration of the electrical characteristics of the photoreceptor, in this case, THF as a residual solvent in the charge transport layer of the coating solution for the charge transport layer and its antioxidant This thermal desorption gas chromatography is used to selectively extract certain BHT.

  Examples of the coating method for the charge transport layer coating solution include a spray method, a bar coating method, a roll coating method, a blade method, a ring method, and a dip coating method. Among these coating methods, the dip coating method is particularly excellent in various respects as described above, and can be used when the charge transport layer 13 is formed.

Each of the charge transport layers 13 preferably has a thickness of 5 to 40 μm, more preferably 10 to 30 μm.
If the film thickness of the charge transport layer 13 is less than 5 μm, the charge retention ability is lowered and it becomes difficult to obtain a clear image, which is not preferable.
On the other hand, if the thickness of the charge transport layer 13 exceeds 40 μm, the resolution of the photoreceptor 1 is lowered.
Therefore, a preferable range of the thickness of the charge transport layer 13 is 5 to 40 μm.

  Each layer of the photosensitive layer 14 is added with one or more sensitizers such as an electron accepting substance and a dye in order to improve sensitivity and further suppress an increase in residual potential and fatigue due to repeated use. Also good.

  Examples of the electron acceptor include acid anhydrides such as succinic anhydride, maleic anhydride, phthalic anhydride, 4-chloronaphthalic anhydride, cyano compounds such as tetracyanoethylene and terephthalmalondinitrile, 4-nitrobenzaldehyde, and the like. Aldehydes, anthraquinones such as anthraquinone and 1-nitroanthraquinone, polycyclic or heterocyclic nitro compounds such as 2,4,7-trinitrofluorenone, 2,4,5,7-tetranitrofluorenone, and diphenoquinone compounds The electron-withdrawing material can be used. Moreover, what polymerized these electron-withdrawing materials can also be used.

As the dye, for example, an organic photoconductive compound such as xanthene dye, thiazine dye, triphenylmethane dye, quinoline pigment or copper phthalocyanine can be used. These organic photoconductive compounds function as optical sensitizers.
Further, an antioxidant or an ultraviolet absorber may be added to each of the layers 12 and 13 of the photosensitive layer 14. In particular, it is preferable to add an antioxidant or an ultraviolet absorber to the charge transport layer 13, and the stability of the coating liquid when each layer is formed by coating can be enhanced. Furthermore, it is particularly preferable to add an antioxidant to the charge transport layer 13. By adding this antioxidant to the charge transport layer, deterioration of the photosensitive layer with respect to an oxidizing gas such as ozone or nitrogen oxide can be reduced.

Examples of the antioxidant include phenol compounds, hydroquinone compounds, tocopherol compounds, and amine compounds. Among these, a hindered phenol derivative or a hindered amine derivative, or a mixture thereof is preferably used.
Moreover, a surface protective layer may be provided as needed.

Embodiment 2
In the first embodiment described above, the configuration of the laminated photosensitive layer in which the photosensitive layer 14 includes the charge generation layer 12 and the charge transport layer 13 has been described. However, as illustrated in FIG. It may be in the form of a single layer including both the generating substance and the charge transport layer, that is, a single-layer type photosensitive layer.
That is, the photoreceptor 1 is a cylindrical conductive substrate 11 made of a conductive material, and a layer laminated on the outer peripheral surface of the conductive substrate 11, and a photosensitive layer 14 containing a charge generating substance and a charge transporting substance. May be formed.

Embodiment 3
As shown in FIG. 3, the charge transport layer 13 may be formed of a plurality of layers.
That is, the charge transport layer is formed by laminating two layers consisting of different charge transport layers 13A and 13B, and polytetrafluoroethylene particles are added to the outermost charge transport layer 13B. That is, in FIG. 3, the charge transport layer 13 includes a first charge transport layer 13A and a second charge transport layer 13B, and the content of the charge transport material in the first charge transport layer 13A and the second charge transport layer 13B. The form in which the second charge transport layer 13B contains polytetrafluoroethylene particles is shown in such a way that the content of the second charge transport layer 13B is different.
As described above, when the charge transport layer 13 is configured by laminating a plurality of layers, it is preferable that polytetrafluoroethylene particles are contained in the layer on the surface side of the charge transport layer 13.

Embodiment 4
FIG. 4 is a schematic cross-sectional view showing the configuration of the image forming apparatus 30 according to the present invention.
The image forming apparatus according to the present invention is not limited to the configuration of the image forming apparatus shown in FIG. 4, and can be electrophotographic regardless of monochrome or color as long as the photoconductor according to the present invention can be used. It can be a variety of printers, copiers, facsimiles, multifunction machines, etc. that utilize the process.
Hereinafter, the configuration and image forming operation of the laser printer 30 on which the photoreceptor 1 according to the first embodiment of the present invention is mounted will be described with reference to FIG.
The laser printer 30 illustrated in FIG. 4 is an example of the image forming apparatus of the present invention, and the image forming apparatus of the present invention is not limited by the following description.

A laser printer 30 as an image forming apparatus includes a photosensitive member 1, a semiconductor laser 31, a rotary polygon mirror 32, an imaging lens 34, a mirror 35, a corona charger 36 as a charging unit, a developing unit 37 as a developing unit, and transfer paper. A cassette 38, a paper feed roller 39, a registration roller 40, a transfer charger 41 as a transfer means, a separation charger 42, a transport belt 43, a fixing device 44, a paper discharge tray 45, and a cleaner 46 as a cleaning means.
The semiconductor laser 31, the rotary polygon mirror 32, the imaging lens 34, and the mirror 35 constitute an exposure unit 49.

  The photoreceptor 1 is mounted on the laser printer 30 so as to be rotatable in the direction of an arrow 47 by a driving unit (not shown). A laser beam 33 emitted from the semiconductor laser 31 is repeatedly scanned in the longitudinal direction (main scanning direction) with respect to the surface of the photoreceptor 1 by the rotary polygon mirror 32. The imaging lens 34 has f-θ characteristics, and the laser beam 33 is reflected by the mirror 35 to form an image on the surface of the photosensitive member 1 for exposure. By scanning the laser beam 33 as described above to form an image while rotating the photoconductor 1, an electrostatic latent image corresponding to image information is formed on the surface of the photoconductor 1.

The corona charger 36, the developing device 37, the transfer charger 41, the separation charger 42, and the cleaner 46 are provided in this order from the upstream side to the downstream side in the rotation direction of the photosensitive member 1 indicated by an arrow 47.
The corona charger 36 is provided on the upstream side of the image forming point of the laser beam 33 in the rotation direction of the photoconductor 1 and uniformly charges the surface of the photoconductor 1. Therefore, when the laser beam 33 exposes the surface of the photosensitive member 1 that is uniformly charged, a difference occurs between the charge amount of the portion exposed by the laser beam 33 and the charge amount of the portion that is not exposed. An electrostatic latent image is formed.

  The developing device 37 is provided on the downstream side in the rotation direction of the photosensitive member 1 with respect to the image forming point of the laser beam 33, supplies toner to the electrostatic latent image formed on the surface of the photosensitive member 1, and converts the electrostatic latent image into toner. Develop as an image. The transfer paper 48 accommodated in the transfer paper cassette 38 is taken out from the transfer paper cassette one by one by the paper feed roller 39 and is given to the transfer charger 41 in synchronism with the exposure to the photosensitive member 1 by the registration roller 40. The toner image is transferred onto the transfer paper 48 by the transfer charger 41. A separation charger 42 provided in the vicinity of the transfer charger 41 discharges the transfer paper onto which the toner image has been transferred and separates it from the photoreceptor 1.

  The transfer paper 48 separated from the photoreceptor 1 is conveyed to the fixing device 44 by the conveying belt 43, and the toner image is fixed by the fixing device 44. The transfer paper 48 on which the image is formed in this manner is discharged toward the paper discharge tray 45. In addition, after the transfer paper 48 is separated by the separation charger 42, the photoreceptor 1 that continues to rotate further cleans foreign matters such as toner and paper dust remaining on the surface by the cleaner 46. The photosensitive member 1 whose surface has been cleaned by the cleaner 46 is neutralized by a neutralizing lamp (not shown) provided together with the cleaner 46 and then further rotated, and a series of image forming operations starting from the charging of the photosensitive member 1 is repeated. .

  Therefore, according to the present invention, there is provided an image forming apparatus comprising the electrophotographic photosensitive member according to the present invention, a charging unit, an exposure unit, a developing unit, a transfer unit, and a fixing unit.

  The image forming apparatus 30 according to the present invention is not limited to the above-described embodiment, and various modifications and changes can be made without departing from the spirit of the present invention. And can be easily understood from the description of the drawings.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail using an Example, this invention is not limited to the following description content.

Example 1
Preparation of intermediate layer 3 parts by weight of titanium oxide (trade name: Tybak TTO-D-1, manufactured by Ishihara Sangyo Co., Ltd.) and 2 parts by weight of commercially available polyamide resin (trade name: Amilan CM8000, manufactured by Toray Industries, Inc.) In addition to 25 parts by weight, dispersion treatment was performed for 8 hours with a paint shaker to prepare 3 kg of an intermediate layer forming coating solution. The obtained coating solution for intermediate layer was filled in a coating tank, and an aluminum drum-shaped support having a diameter of 30 mm and a length of 357 mm was immersed as a conductive support and then pulled up to form an intermediate layer having a thickness of 1 μm.

Production of Charge Generation Layer Next, titanyl phthalocyanine 1 having an X-ray diffraction spectrum in which a Bragg angle (2θ ± 0.2 °) with respect to X-ray of CuKα 1.541５４ as a charge generation material shows a main peak at 27.3 °. 1 part by weight of butyral resin (trade name: ESREC BM-2, manufactured by Sekisui Chemical Co., Ltd.) as a binder resin and 98 parts by weight of methyl ethyl ketone are mixed and dispersed in a paint shaker for 8 hours to form a charge generation layer. A coating solution of 3 liters was prepared.
The obtained coating solution for forming the charge generation layer is applied to the surface of the undercoat layer previously provided in the same manner as in the formation of the undercoat layer, and then naturally dried to form a charge generation layer having a thickness of 0.3 μm. did.

As a charge transport material, the following formula:

100 parts by weight of the compound 1 (T2269: manufactured by Tokyo Chemical Industry Co., Ltd.), 180 parts by weight of a polycarbonate resin (TS2050: manufactured by Teijin Chemicals), and 1,053 parts by weight of tetrahydrofuran as a solvent, a solid content of 21 3 kg of a coating solution for forming a weight% charge transport layer was prepared.
This charge transport layer forming coating solution was applied to the surface of the charge generation layer previously provided by an immersion method and dried at 110 ° C. for 1 hour to form a charge transport layer having a thickness of 28 μm. In this way, the multilayer photoreceptor shown in FIG. 1 was produced.

  Hereinafter, the solid content concentration of the surface layer coating suspension (charge transport layer forming coating solution) in Examples and Comparative Examples is unified to 21 wt% as in Example 1. Thus, when the same surface layer coating suspension was applied and the film thickness was the same, the amount of residual THF contained immediately after the formation of the coating film in this example and the comparative example, and 2,6 The amount of -di-t-butyl-4-methylphenol (BHT) can be assumed to be a constant value.

Example 2
In the same manner as in Example 1, an intermediate layer and a charge generation layer were produced. Thereafter, the charge transport layer forming coating solution used in Example 1 was applied to the surface of the charge generation layer previously provided by an immersion method and dried at 120 ° C. for 1 hour to form a charge transport layer having a thickness of 28 μm. Thus, a photoreceptor of Example 2 was produced.

Example 3
In the same manner as in Example 1, an intermediate layer and a charge generation layer were produced. Thereafter, the charge transport layer forming coating solution used in Example 1 was applied to the surface of the charge generation layer previously provided by an immersion method and dried at 130 ° C. for 1 hour to form a charge transport layer having a thickness of 28 μm. Thus, a photoconductor of Example 3 was produced.

Example 4
In the same manner as in Example 1, an intermediate layer and a charge generation layer were produced. Thereafter, the charge transport layer forming coating solution used in Example 1 was applied to the surface of the charge generation layer previously provided by an immersion method and dried at 140 ° C. for 1 hour to form a charge transport layer having a thickness of 28 μm. Thus, a photoconductor of Example 4 was produced.

Comparative Example 1
In the same manner as in Example 1, an intermediate layer and a charge generation layer were produced. Thereafter, the charge transport layer forming coating solution used in Example 1 was applied to the surface of the charge generation layer previously provided by an immersion method and dried at 100 ° C. for 1 hour to form a charge transport layer having a thickness of 28 μm. Thus, a photoreceptor of Comparative Example 1 was produced.

Comparative Example 2
In the same manner as in Example 1, an intermediate layer and a charge generation layer were produced. Thereafter, the charge transport layer forming coating solution used in Example 1 was applied to the surface of the charge generation layer previously provided by an immersion method and dried at 150 ° C. for 1 hour to form a charge transport layer having a thickness of 28 μm. Thus, a photoreceptor of Comparative Example 2 was produced.

Comparative Example 3
In the same manner as in Example 1, an intermediate layer and a charge generation layer were produced. Thereafter, the charge transport layer forming coating solution used in Example 1 was applied to the surface of the charge generation layer previously provided by an immersion method and dried at 160 ° C. for 1 hour to form a charge transport layer having a thickness of 28 μm. Thus, a photoreceptor of Comparative Example 3 was produced.

Evaluation 1. Evaluation of residual THF / BHT amount The set temperature in the thermal desorption gas chromatography in the present invention was selected to be equal to or lower than the boiling point of BHT serving as a reference substance. That is, using the surface layer peeled off from the photosensitive layer as a sample, using EGA-PY 3030D manufactured by Frontier Laboratories, the temperature rising condition was set to 180 ° C. to 200 ° C., followed by thermal desorption, and then once the liquid nitrogen temperature (− The residual THF and BHT in the sample were detected and analyzed using an Agilent Technologies 7890A GC system and a 5975C mass detection system set to 40 ° C to 180 ° C temperature rising conditions arranged at the subsequent stage. .

2. Electrical characteristics evaluation For the obtained photoreceptor, a photocopier produced in the example / comparative example was mounted on a test copier modified from a digital copier (trade name: MX-2600, manufactured by Sharp Corporation). A surface potential meter (model 344, manufactured by TRECJAPAN) was provided so that the surface potential of the photoconductor in the image forming process could be measured, and the electrical characteristics and image quality of each photoconductor were evaluated. Note that a laser beam having a wavelength of 780 nm was used as the light source.

  First, using the copying machine, the surface potential of the photosensitive member at the developing portion, specifically, the surface potential VL of the photosensitive member in the black background during exposure was measured in order to see the sensitivity of the photosensitive member. These surface potentials VL were measured at an initial temperature and immediately after 100 k sheets of continuous repeated copying in a room temperature / normal humidity (abbreviated as “N / N”) environment of 25 ° C./50% RH (relative humidity).

Evaluation of Photoreceptor Electrical Characteristics The initial potential measurement value VL (−V) of the photoconductor, the photoconductor surface potential measurement value VL (−V) immediately after 100 k continuous repeated copies, and the difference (variation width) ΔVL between these measurement values The measurement results were evaluated according to the following criteria.
VG: The initial potential measurement value VL is −100V or more, and the fluctuation range ΔVL after 100k actual shooting is 20V or less.
G: The initial potential measurement value VL is −100V or more, and the fluctuation range ΔVL after 100k actual shooting is greater than 20V and 40V or less.
NB: The initial potential measurement value VL is −100V or more, and the fluctuation range ΔVL after 100k actual shooting is greater than 40V and 70V or less.
B: The initial potential measurement value VL is less than −100, or the fluctuation width ΔVL after 100k actual shooting is greater than 70V.

From the above results, it was found that the photoconductors obtained in Examples 1 to 4 were more stable in electrical characteristics over a longer period than the photoconductors obtained in Comparative Examples 1 to 3.
That is, in the measurement results of thermal desorption chromatography, the ratio A / B based on the integrated intensity of THF / BHT (= A / B) is in the range of 0.2 or less. The evaluation test showed a stable transition of electrical characteristics. Among them, the photoconductor according to Example 3 in which the ratio A / B is 0.05 or less shows a more stable transition of electric characteristics, and according to Examples 2 and 4 in which the ratio A / B is 0.1 or less. It was found that the photoreceptor also showed a good transition in electrical characteristics.
On the other hand, the photoconductors of Comparative Examples 1 to 3 having a ratio A / B larger than 0.2 in the measurement results of thermal desorption chromatography are the photoconductors of Comparative Examples 2 and 3 prepared by a drying process at a relatively high temperature. As a result, it was found that the initial electrical characteristics of the photoconductor deteriorated. Further, the photoconductor according to Comparative Example 1 produced by a drying process at a relatively low temperature showed good initial characteristics of the photoconductor, but the service time was long and the electric characteristics were remarkably deteriorated.

  The outermost surface layer of the electrophotographic photoreceptor according to the present invention contains a specific coating solution solvent and an antioxidant thereof in a specific ratio, so that the electrophotographic photoreceptor that is electrically stable for a long period of time and the photoreceptor are obtained. It is possible to provide an image forming apparatus provided.

DESCRIPTION OF SYMBOLS 1 Electrophotographic photoreceptor 11 Conductive substrate 12 Charge generation layer 13, 13A, 13B Charge transport layer 14 Photosensitive layer 15 Undercoat layer (intermediate layer)
30 Laser printer (image forming device)
DESCRIPTION OF SYMBOLS 31 Semiconductor laser 32 Rotating polygon mirror 34 Imaging lens 35 Mirror 36 Corona charger 37 Developing device 38 Transfer paper cassette 39 Paper feed roller 40 Registration roller 41 Transfer charger 42 Separation charger 43 Conveyor belt 44 Fixing device 45 Paper discharge tray 46 Cleaner 47 Arrow 48 Transfer paper 49 Exposure means 50 Static eliminator

Claims (7)

A laminated photosensitive layer in which a charge generating layer containing at least a charge generating material and a charge transporting layer containing a charge transporting material are laminated in this order, or a single-layered photosensitive layer containing a charge generating material and a charge transporting material is a conductive substrate. An electrophotographic photoreceptor laminated on the top,
The outermost surface layer of the electrophotographic photosensitive member was compared with the residual amount (B) of 2,6-di-t-butyl-4-methylphenol in the integrated intensity comparison by analyzing the residual solvent amount using thermal desorption gas chromatography. An electrophotographic photosensitive member having a ratio A / B ≦ 0.2 with respect to a residual amount ratio A / B of the residual amount (A) of tetrahydrofuran.   2. The electrophotographic photosensitive member according to claim 1, wherein the analysis of the residual solvent amount by the thermal desorption gas chromatography is an analysis based on an integrated intensity ratio of the residual solvent amount at a thermal desorption temperature of 200 ° C. or less.   The electrophotographic photosensitive member according to claim 1, wherein the outermost surface layer has a ratio A / B ≦ 0.1.   The electrophotographic photosensitive member according to claim 1, wherein the outermost surface layer has a ratio A / B ≦ 0.05.   The electrophotographic photosensitive member according to claim 1, wherein the outermost surface layer of the electrophotographic photosensitive member is formed using an outermost surface layer coating solution containing tetrahydrofuran as a main solvent. Body manufacturing method.   The method for producing an electrophotographic photosensitive member according to claim 5, wherein the outermost surface layer of the photographic photosensitive member is formed by a drying step under a drying temperature condition of more than 100 ° C. and less than 150 ° C.   An electrophotographic photosensitive member according to any one of claims 1 to 4, a charging means for charging the electrophotographic photosensitive member, and an electrostatic latent image is formed by exposing the charged electrophotographic photosensitive member. Exposure means for developing, developing means for developing the electrostatic latent image with toner to form a toner image, transfer means for transferring the toner image onto a recording material, and the transferred toner image on the recording material An image forming apparatus comprising fixing means for fixing to an image.