JP2005062521A - Electrophotographic photoreceptor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor which has an undercoat layer and a photosensitive layer and prevents a defective image from appearing while having good electrical properties, and further has an excellent mechanical property, such as adhesiveness to the photosensitive layer as well. <P>SOLUTION: The problems are solved by incorporating a black inorganic compound of 10<SP>-1</SP>to 10<SP>4</SP>Ωcm in electric resistance of a 9.8 MPa green compact into the undercoat layer. More specifically, the electrophotographic photoreceptor having the undercoat layer and the photosensitive layer on a conductive substrate is characterized by that the undercoat layer contains the black inorganic compound of 10<SP>-1</SP>to 10<SP>4</SP>Ωcm in electric resistance of the 9.8 MPa green compact. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention is mounted on an electrophotographic apparatus that forms an image using coherent light such as a semiconductor laser beam as an exposure means, and has an electrical property and an image property in an electrophotographic photoreceptor having an undercoat layer and a photosensitive layer. The present invention relates to a good electrophotographic photosensitive member.

  Conventionally, inorganic photoconductive materials such as selenium, selenium-tellurium alloy, arsenic selenide, and cadmium sulfide have been widely used for electrophotographic photoreceptors. However, in recent years, organic materials that are low pollution and easy to manufacture are used. An electrophotographic photosensitive member using a photoconductive material is used as a photosensitive layer. In particular, a laminated type photoconductor composed of a charge generation layer and a charge transfer layer which separates the function of absorbing light to generate charges and the function of transporting the generated charges has become the mainstream. These photoreceptors are widely used in fields such as copying machines and laser printers.

  The electrophotographic photosensitive member has a basic structure in which a photosensitive layer is formed on a conductive support. An undercoat layer is provided between the photosensitive layer and the support in order to eliminate image defects due to charge injection from the support or defects in the support, to improve adhesion to the photosensitive layer, and to improve chargeability. ing.

  Conventionally, as the undercoat layer, for example, polyamide resin, polyester resin, polyurethane resin, polycarbonate resin, epoxy resin, polyurethane resin, vinyl chloride resin, acrylic resin, phenol resin, urea resin, melamine resin, guanamine resin, It is known to use resin materials such as polyvinyl alcohol, casein, and gelatin. Among these resin materials, a solvent-soluble polyamide resin is particularly preferable. Further, as an undercoat layer in which an inorganic material is dispersed in a polyamide resin, for example, titanium oxide particles having an average primary particle diameter of 100 nm or less are dispersed in a solvent-soluble polyamide resin (for example, Patent Document 1). .

  Recently, in the trend of digitization, electrophotographic devices have become digital devices. Since a digital electrophotographic apparatus forms an image using coherent light such as a semiconductor laser, it is necessary to suppress image defects of an interference fringe pattern. This is considered to be due to the fact that the light transmitted through the charge generation layer is reflected on the surface of the substrate or the undercoat layer, causing interference between the reflected light and the reflected light on the surface of the charge transport layer. In order to suppress the image defect of the interference fringe pattern, the undercoat layer in which the above-described titanium oxide particles of 100 nm or less are dispersed in the binder resin is insufficient. In order to scatter light transmitted through the charge generation layer and to prevent interference with reflected light on the surface of the charge transport layer, inorganic particles having an average primary particle size of less than 0.1 μm and a particle size of 0.1 μm or more Although an undercoat layer (for example, Patent Document 2) containing particles having a particle size of less than 2 μm has been proposed, the image defect of the interference fringe pattern can be suppressed to some extent, but it is not sufficient, and further improvement is desired. Yes. From the same concept, addition of organic fine particles having a specific particle size (for example, Patent Document 3) has been studied.

In addition, an undercoat layer in which a black pigment is dispersed is also known, and carbon black, iron trioxide, etc. have been mainly used as the black pigment, but the resistance value of the undercoat layer is the degree of dispersion in carbon black. The resistance value is difficult to control, and iron trioxide is easy to be magnetized, and its specific gravity is as large as 5.2, resulting in poor dispersibility when dispersed in a solvent. It was not right.
JP-A-3-24558 JP 2001-209200 A JP-A-10-177267

  As described above, the conventional electrophotographic photosensitive member having the undercoat layer and the photosensitive layer has an interference pattern image defect when used in an electrophotographic apparatus that forms an image using coherent light such as laser light. It was difficult to eliminate. An object of the present invention is to provide an electrophotographic photosensitive member having an undercoat layer and a photosensitive layer, while having good electrical characteristics, no image defects are observed, and mechanical characteristics such as adhesion to the photosensitive layer. It is an object to provide an excellent electrophotographic photoreceptor.

The present inventor has found that the above problem can be solved by including a black inorganic compound having an electrical resistance value of 1 to 10 ⁴ Ω · cm in the undercoat layer in the undercoat layer. The invention has been reached. That is, the gist of the present invention is an electrophotographic photosensitive member having an undercoat layer and a photosensitive layer on a conductive substrate, wherein the undercoat layer has an electrical resistance value of 1 to 10 ⁴ Ω · cm. An electrophotographic photoreceptor characterized by a certain black inorganic compound.

  By using the electrophotographic photosensitive member having the undercoat layer of the present invention, the generation of interference fringe patterns can be suppressed even in an electrophotographic apparatus using coherent light as a light source, and both image characteristics, electrical characteristics, and mechanical characteristics can be suppressed. A good photoreceptor can be provided.

The electrophotographic photoreceptor of the present invention comprises a subbing layer containing a black inorganic compound having an electrical resistance value of 1 to 10 ⁴ Ω · cm between a conductive support and a photosensitive layer. Have

The black inorganic compound in the present invention may be anything as long as the electrical resistance value of the 9.8 MPa green compact is 1 to 10 ⁴ Ω · cm, but in the Hunter Lab color system, the L value is A black material of 25 or less is preferably used. In addition, other inorganic compounds can be used in combination with the undercoat layer, but in order to obtain a sufficient effect, a layer having an L value of 20 or less is more preferably used.

  The particle diameter of the black inorganic compound is not particularly limited as long as it can form a uniform undercoat layer. From the viewpoint of the stability of the coating liquid when forming the undercoat layer, it is observed by an electron microscope. The average primary particle size is usually 1 μm or less, more preferably 0.5 μm or less, usually 0.03 μm or more, and more preferably 0.1 μm or more.

If the electrical resistance of the black inorganic compound is too small, the change in the volume resistivity of the undercoat layer relative to the content becomes too large, making it difficult to produce a photoreceptor. Usually, by a method in accordance with JIS K 7194, A material having an electric resistance of 1 Ω · cm or more when measured with a 9.8 MPa compact is used. Also, if the electrical resistance becomes too large, it is necessary to contain a large amount of black inorganic compound or other conductive particles in order to bring the volume resistivity of the undercoat layer to a desired value. Since the ratio of the binder resin is reduced and the strength of the layer is reduced and the manufacturing cost is increased, the electrical resistance when measured with a 9.8 MPa compact is similarly 10 ⁴ Ω · cm or less. Is used.

Examples of the black inorganic compound include surface-treated carbon particles and various metal oxides, particularly black titanium oxide. Although ordinary titanium oxide is white, as a method for obtaining black titanium oxide suitable for the present invention, for example, a mixture of titanium dioxide powder and metal titanium powder as disclosed in Japanese Patent Publication No. 52-12733 is used. 550-1100 ° C under vacuum or reducing atmosphere
A method of heating at a temperature, a method of heating and reducing titanium dioxide powder in a special atmosphere such as anhydrous hydrazine gas, as disclosed in JP-A-64-72921, and a method disclosed in JP-A-5-193942. Examples include a method of heating titanium dioxide powder and sodium borohydride at 300 to 950 ° C. in an inert atmosphere, and any of the black titanium oxides in the present invention can be used. Since the reducing gas which is sintered and coarsened is corrosive and difficult to handle, it is preferable to use a method in which titanium dioxide powder and sodium borohydride are heated in an inert atmosphere.

  The undercoat layer in the present invention may contain metal compound particles separately from the black inorganic compound. The metal compound particles that can be used in combination are preferably n-type (electron transporting) particles. Specific examples of such metal compounds include titanates such as strontium titanate, calcium titanate and barium titanate; white titanium oxide; metal oxides such as titanium oxide, nickel oxide, zinc oxide and cobalt oxide. And those obtained by doping titanium oxide with metal elements such as niobium, antimony, tungsten, indium, nickel, iron, and silicon. Among these, white titanium oxide particles are preferable from the viewpoint of price and stability as a compound. These metal compound particles are preferably particles having an average primary particle size of usually 100 nm or less from the viewpoint of dispersion stability of the coating solution for forming the undercoat layer and from the viewpoint of electrical characteristics such as residual potential. Moreover, in order to stabilize the dispersion liquid in which the inorganic oxide particles are dispersed, the metal compound may be hydrophobized.

  The abundance ratio of the metal compound particles that may be used in combination with the black inorganic compound is not particularly limited, but in order to sufficiently obtain the effects of the present invention, the entire metal in which the black inorganic compound is contained in the undercoat layer It is preferable that it is 10 weight% or more with respect to a compound particle.

  Usually, the undercoat layer is formed by binding with a binder resin. As the binder resin, polyamide resin, polyester resin, polyurethane resin, polycarbonate resin, epoxy resin, polyurethane resin, vinyl chloride resin, acrylic resin, phenol resin, urea resin, melamine resin, guanamine resin, polyvinyl alcohol, casein, Resin materials such as gelatin can be used.

  Of these, a polyamide resin having excellent adhesion to the support and low solubility in the solvent used in the coating solution for forming the photosensitive layer is preferable. Among them, a copolymerized polyamide resin having a diamine component represented by the following general formula as a constituent component is particularly preferable.

(A and B each independently represent a cyclohexyl ring optionally having a substituent, and R ¹ and R ² each independently represent hydrogen, an alkyl group, an alkoxy group, or an aryl group.)
Although the ratio of the black inorganic compound and the binder resin can be arbitrarily selected, from the viewpoint of the adhesiveness of the undercoat layer, the mechanical strength, the stability of the coating solution, and the electrical characteristics, The black inorganic compound is usually 0.5 parts by weight or more, more preferably 2 parts by weight or more, and usually 6 parts by weight or less, more preferably 4 parts by weight or less. When the black inorganic compound and other metal compound particles are used in combination, the sum of the black inorganic compound and the other metal compound particles is preferably the above ratio.

  The undercoat layer may be formed by a conventional method. That is, it is formed by dissolving or dispersing the material contained in the layer in a solvent, and coating and drying the obtained coating solution on a conductive support. In the coating liquid, inorganic compound particles such as silica and titanium oxide, organic compound particles, photoconductive substances, and antioxidants are added as necessary, as long as the properties of the undercoat layer and the dispersion stability of the coating liquid are not deteriorated. Agents, dispersants, leveling agents, other additives, etc. may be added.

  The undercoat layer may be applied by any application method as long as it can be applied uniformly to some extent, but is generally applied by dip coating, spray coating, nozzle coating, or the like.

  If the thickness of the undercoat layer is too thin, the effect on local charging failure will not be sufficient, and conversely if too thick, the residual potential will increase or the adhesive strength between the conductive substrate and the photosensitive layer will decrease. Cause. The film thickness of the undercoat layer of the present invention is usually 0.1 μm or more, preferably 1 μm or more, and usually 18 μm or less, preferably 10 μm or less.

If the volume resistivity of the undercoat layer is too low, the charge easily moves and the photoreceptor is not charged. Therefore, it is preferably used at 1 × 10 ⁷ Ωcm or more. If the volume resistivity is too high, the residual potential is reduced. Since it leads to accumulation, it is preferably used at 1 × 10 ¹⁴ Ωcm or less.
<Support>
As the conductive support used in the present invention, any of those used in known electrophotographic photoreceptors can be used. Specifically, for example, drums, sheets made of metal materials such as aluminum, stainless steel, copper, nickel, etc., laminates or vapor depositions of these metal foils, or aluminum, copper, palladium, tin oxide, indium oxide on the surface, etc. Insulating supports such as polyester film and paper provided with a conductive layer. Furthermore, a plastic film, a plastic drum, paper, a paper tube, and the like obtained by applying a conductive material such as metal powder, carbon black, copper iodide, and a polymer electrolyte together with an appropriate binder to conduct a conductive treatment may be used. Further, a plastic sheet or drum containing a conductive material such as metal powder, carbon black, or carbon fiber and becoming conductive can be used. Examples thereof include a plastic film and a belt subjected to conductive treatment with a conductive metal oxide such as tin oxide and indium oxide.

Among these, an endless pipe made of metal such as aluminum is a preferable support. An endless pipe made of aluminum or its alloy is formed by processing such as extrusion, drawing, and ironing. What was shape | molded may be used as it is, and what added processes, such as cutting, grinding, and grinding | polishing further, may be used. The surface of the conductive support can be subjected to various treatments such as oxidation treatment and chemical treatment within a range that does not affect the image quality.
<Photosensitive layer>
A photosensitive layer is formed on the undercoat layer. The photosensitive layer may have a single layer structure (hereinafter sometimes referred to as a single layer type photosensitive layer) containing a charge generation material, a charge transport material and a binder resin in a single layer, or contains a charge generation material. A stacked structure in which a charge generation layer and a charge transport layer containing a charge transport material are stacked (hereinafter also referred to as a stacked type photoreceptor) may be used.
<Charge generation layer>
Examples of the charge generation material used in the charge generation layer of the multilayer photosensitive layer include phthalocyanine, azo, perylene, quinacridone, polycyclic quinone, pyrylium salt, indigo, thioindigo, anthanthrone, pyranthrone, cyanine, and various organic pigments and dyes. Can be used. Metal-free phthalocyanines, copper, indium, gallium, tin, titanium, zinc, vanadium, silicon, and other metals, or phthalocyanines coordinated with oxides, hydroxides, and chlorides, monoazo, bisazo, trisazo, polyazos An azo pigment such as azo pigment and perylene pigment are preferred.

Among these charge generation materials, metal-free and metal-containing phthalocyanines can provide a photosensitive member with high sensitivity to a laser beam having a relatively long wavelength, and monoazo, bisazo, trisazo, etc. Azo pigments are preferred because they are excellent in that they have sufficient sensitivity to white light and relatively short wavelength laser light.

Further, among phthalocyanines, oxytitanium phthalocyanine, in which the black angle (2θ ± 0.2 °) of the X-ray diffraction spectrum with respect to CuKα characteristic X-ray shows a main diffraction peak at 27.3 °, 9.3 °, 13 Oxytitanium phthalocyanine, 9.2, 14.1, 15.3, 19.7 showing main diffraction peaks at .2 °, 26.2 ° and 27.1 °.
Dihydroxysilicon phthalocyanine having a main diffraction peak at 27.1 °, 8.
Dichlorotin phthalocyanine showing major diffraction peaks at 5 °, 12.2 °, 13.8 °, 16.9 °, 22.4 °, 28.4 ° and 30.1 °, 7.5 °, 9.9 Hydroxygallium phthalocyanine showing main diffraction peaks at °, 12.5 °, 16.3 °, 18.6 °, 25.1 ° and 28.3 °, 7.4 °, 16.6 ° and 25.5 ° And chlorogallium phthalocyanine showing a diffraction peak at 28.3 ° is preferred.

  The charge generation layer can be obtained by coating and drying a coating solution obtained by dissolving or dispersing fine particles of these substances and a binder polymer in a solvent.

  As binder resins, polymers and copolymers of vinyl compounds such as styrene, vinyl acetate, vinyl chloride, acrylic esters, methacrylic esters, vinyl alcohol, ethyl vinyl ether, polyvinyl acetals, polycarbonates, polyesters, polyamides, polyurethanes, celluloses Examples include ether, phenoxy resin, silicon resin, and epoxy resin. As the binder resin, only one kind of these resins may be used, or a mixture of two or more kinds may be used. Among these resins, a polyvinyl acetal resin and a phenoxy resin are preferable because of the dispersion stability of the pigment.

  Solvents include alcohols such as methanol and propanol, ethers such as 1,4-dioxane and 1,2-dimethoxyethane, ketones such as methyl ethyl ketone, cyclohexanone and 4-methoxy-4-methylpentanone-2. And hydrocarbons such as toluene. Only one of these solvents may be used, or a mixture of two or more may be used. Among these solvents, 1,2-methoxyethane and 4-methoxy-4-methylpentanone are preferable because of the crystal stability of the pigment.

  The ratio of the charge generating material to the binder polymer is not particularly limited, but generally 5 to 500 parts by weight, preferably 20 to 300 parts by weight of the binder polymer is used with respect to 100 parts by weight of the charge generating material.

  The charge generation layer may be a vapor deposition film of the charge generation material.

The thickness of the charge generation layer is 0.05 to 5 μm, preferably 0.1 to 2 μm.
<Charge transport layer>
As the charge transport material in the charge transport layer of the multilayer photosensitive layer, polymer compounds such as polyvinyl carbazole, polyvinyl pyrene, polyacenaphthylene, various pyrazoline derivatives, oxazole derivatives, hydrazone derivatives, stilbene derivatives, butadiene derivatives, aryl Low molecular weight compounds such as amine derivatives can be used. Today, low molecular weight compounds such as hydrazone derivatives, stilbene derivatives, butadiene derivatives, and hydrazone derivatives are preferably used.

The charge transport layer can be obtained by coating and drying a coating solution obtained by dissolving these charge transport material and binder polymer in a solvent on the charge generation layer. The binder polymer is preferably a polymer that has good compatibility with the charge transport material and does not crystallize or phase-separate after formation of the coating film. Examples thereof include polymers and copolymers of vinyl compounds such as styrene, vinyl acetate, vinyl chloride, acrylic acid esters, methacrylic acid esters, vinyl alcohol, ethyl vinyl ether, polyvinyl acetals, polycarbonates, polyesters, polysulfones, polyphenylene oxides. , Polyurethane, cellulose ester, cellulose ether, phenoxy resin, silicon resin, epoxy resin, and polymers obtained by introducing the above-described low-molecular compound charge transfer materials into the main chain and / or side chain.

  Among these, a polycarbonate resin is preferably used in terms of mechanical properties such as wear resistance and compatibility of the charge transport material and the binder polymer in the solution.

  The ratio of the binder resin to the charge transporting material is such that the electrical characteristics deteriorate if the amount of the charge transporting material is too small relative to the binder resin. Particularly preferably, it is used in an amount of 30 parts by weight or more. Further, if the amount of the charge transport material is too large, the hardness of the charge transport layer decreases, wear during use increases, and the surface is easily damaged and image defects are likely to occur. Part or less, preferably 150 parts by weight or less, and particularly preferably 100 parts by weight or less.

  The thickness of the charge transport layer is usually 10 to 50 μm, preferably 13 to 35 μm.

  You may add an electron withdrawing compound to a charge transport layer as needed. Electron-withdrawing compounds include tetracyanoquinodimethane, dicyanoquinomethane, cyano compounds such as aromatic esters having a dicyanoquinovinyl group, nitro compounds such as 2,4,6-trinitrofluorenone, and condensation of perylene. Polycyclic aromatic compounds, diphenoquinone derivatives, quinones, aldehydes, ketones, esters, acid anhydrides, phthalides, substituted and unsubstituted salicylic acid metal complexes, substituted and unsubstituted salicylic acid metal salts, aromatic carboxylic acids And metal salts of aromatic carboxylic acids. Preferably, cyano compounds, nitro compounds, condensed polycyclic aromatic compounds, diphenoquinone derivatives, metal complexes of substituted and unsubstituted salicylic acids, metal salts of substituted and unsubstituted salicylic acids, metal complexes of aromatic carboxylic acids, aromatic carboxylic acids A metal salt is preferably used.

The photosensitive layer of the electrophotographic photoreceptor of the present invention has a film forming property, flexibility, coating property, mechanical strength, slipperiness, plasticizer, antioxidant, etc. in order to improve gas resistance properties such as ozone and NOx, An ultraviolet absorber, inorganic particles, resin particles, wax, silicone oil, and a leveling agent may be contained.
<Single layer type photoreceptor>
When the photosensitive layer has a single-layer structure, a known material in which a photosensitive material is dispersed in a binder is used. For example, a material in which a charge generating material is dispersed as a main component in a binder resin, or a material in which a charge generating material and a charge transporting material are dispersed as main components in a binder resin is used. In these cases, well-known materials that can be used in the laminated photosensitive layer can be used as the charge generation material, the charge transport material, and the binder resin. Moreover, the solvent which can be used for charge transport layer formation of a laminated type photosensitive layer can be used suitably for the solvent of the coating liquid for photosensitive layer formation similarly.

For example, in the case where a charge generating material and a charge transporting material are the main components and dispersed in a binder resin, the charge generating material is dispersed in a charge transporting medium having a blending ratio such as a charge transporting layer of a multilayer photoreceptor. Is done. In this case, the particle size of the charge generating material needs to be sufficiently small, and is preferably 1 μm or less, more preferably 0.5 μm or less. When the amount of the charge generating material dispersed in the photosensitive layer is too small, sufficient sensitivity cannot be obtained. On the other hand, when the amount is too large, there are problems such as a decrease in chargeability and a decrease in sensitivity. It is used in the range of not less than wt%, preferably not less than 1 wt%, and usually not more than 50 wt%, preferably not more than 20 wt%. The film thickness of the single-layer type photosensitive layer is usually 5 μm or more, preferably 10 μm or more, and usually 100 μm or less, preferably 50 μm or less.
<Other functional layers>
An overcoat layer may be used on the photosensitive layer in order to improve mechanical properties and gas resistant properties such as ozone and NOx. Furthermore, you may have an adhesive layer, an intermediate | middle layer, a transparent insulating layer, etc. as needed.

Further, an intermediate layer may be further provided between the undercoat layer and the photosensitive layer, but the undercoat layer of the present invention alone exhibits good electrical characteristics including electrical characteristics during repetition. It is preferable not to provide such an intermediate layer in terms of productivity and cost.
<Layer formation method>
The undercoat layer and the photosensitive layer are formed by applying a coating solution on a conductive support by a spray method, a spiral method, a ring method, a dipping method or the like.

  Examples of the spray used in the spray method include air spray, airless spray, electrostatic air spray, electrostatic airless spray, rotary atomizing electrostatic spray, hot spray, and hot airless spray. In order to make the film thickness uniform, a method using a rotary atomizing electrostatic spray described in Republished Hei 1-805198 is preferable.

Examples of the spiral method include a method using an injection coating machine or a curtain coating machine described in Japanese Patent Laid-Open No. 52-119651, and a method in which a paint is streaked from a minute opening described in Japanese Patent Laid-Open No. 1-2231966. And a method using a multi-nozzle body disclosed in JP-A-3-193161.
<Image forming apparatus>
An image forming apparatus such as a copying machine or a printer using the electrophotographic photosensitive member of the present invention includes at least charging, exposure, development, transfer, and static elimination processes. Also good.

  As the charging method (charging machine), for example, in addition to corotron and scorotron charging using corona discharge, a direct charging means for charging a surface by contacting a directly charged member to which a voltage is applied may be used. As the direct charging means, any one such as contact charging using a conductive roller, brush, or film may be used, and any of those that involve air discharge or injection charging that does not involve air discharge is possible. Among these, scorotron charging is preferable in the charging method using corona discharge in order to keep the dark portion potential constant. As a charging method in the case of a contact charging device using a conductive roller or the like, DC charging or AC superimposed DC charging can be used.

  As the exposure light, halogen lamps, fluorescent lamps, lasers (semiconductors, He—Ne), LEDs, photoconductor internal exposure systems, and the like are used. As digital electrophotographic systems, lasers, LEDs, optical shutter arrays, and the like are used. preferable. As the wavelength, in addition to monochromatic light of 780 nm, monochromatic light near a short wavelength in the 600 to 700 nm region and short wavelength monochromatic light in the 380 to 500 nm region can be used.

For the development process, a dry development method such as cascade development, one-component insulating toner development, one-component conductive toner development, two-component magnetic brush development, or the like is used. As the toner, in addition to the pulverized toner, a polymerized toner such as suspension polymerization or emulsion polymerization aggregation method can be used. In particular, in the case of a polymerized toner, a toner having a small particle diameter of about 4 to 8 μm in average diameter is used. The polymerized toner is excellent in charging uniformity and transferability and is suitably used for high image quality.

  For the transfer process, electrostatic transfer methods such as corona transfer, roller transfer, and belt transfer, pressure transfer methods, and adhesive transfer methods are used. For fixing, heat roller fixing, flash fixing, oven fixing, pressure fixing, or the like is used.

  For cleaning, brush cleaner, magnetic brush cleaner, electrostatic brush cleaner, magnetic roller cleaner, blade cleaner, etc. are used.

  In many cases, the static elimination step is omitted, but when used, a fluorescent lamp, LED, or the like is used, and an exposure energy that is three times or more of the exposure light is often used as the intensity. In addition to these processes, a pre-exposure process and an auxiliary charging process may be included.

  An embodiment of an image forming apparatus using the electrophotographic photosensitive member of the present invention will be described with reference to FIG. However, the embodiment is not limited to the following description, and can be arbitrarily modified without departing from the gist of the present invention.

  As shown in FIG. 1, the image forming apparatus includes an electrophotographic photosensitive member 1, a charging device 2, an exposure device 3, and a developing device 4, and further, a transfer device 5, a cleaning device 6 and a fixing device as necessary. A device 7 is provided.

  The electrophotographic photoreceptor 1 is not particularly limited as long as it is the above-described electrophotographic photoreceptor of the present invention, but in FIG. 1, as an example, a drum in which the above-described photosensitive layer is formed on the surface of a cylindrical conductive support. The photoconductor is shown. A charging device 2, an exposure device 3, a developing device 4, a transfer device 5, and a cleaning device 6 are disposed along the outer peripheral surface of the electrophotographic photosensitive member 1.

  The charging device 2 charges the electrophotographic photosensitive member 1 and uniformly charges the surface of the electrophotographic photosensitive member 1 to a predetermined potential. In FIG. 1, a roller-type charging device (charging roller) is shown as an example of the charging device 2, but other corona charging devices such as corotron and scorotron, and contact-type charging devices such as charging brushes are often used.

  In many cases, the electrophotographic photosensitive member 1 and the charging device 2 are designed to be removable from the main body of the image forming apparatus as a cartridge including both of them (hereinafter, appropriately referred to as a photosensitive cartridge). For example, when the electrophotographic photoreceptor 1 or the charging device 2 deteriorates, the photoreceptor cartridge can be removed from the image forming apparatus main body, and another new photosensitive cartridge can be mounted on the image forming apparatus main body. ing. Also, the toner described later is often stored in the toner cartridge and designed to be removable from the main body of the image forming apparatus. When the toner in the used toner cartridge runs out, this toner cartridge is removed. It can be removed from the main body of the image forming apparatus and another new toner cartridge can be mounted. Further, a cartridge equipped with all of the electrophotographic photosensitive member 1, the charging device 2, and the toner may be used.

  The type of the exposure apparatus 3 is not particularly limited as long as it can expose the electrophotographic photoreceptor 1 to form an electrostatic latent image on the photosensitive surface of the electrophotographic photoreceptor 1. Specific examples include halogen lamps, fluorescent lamps, lasers such as semiconductor lasers and He—Ne lasers, LEDs, and the like. Further, exposure may be performed by a photoreceptor internal exposure method. The light used for the exposure is arbitrary. For example, the exposure may be performed using monochromatic light with a wavelength of 780 nm, monochromatic light with a wavelength slightly shorter than 600 nm to 700 nm, or monochromatic light with a short wavelength of 380 nm to 500 nm. .

  The type of the developing device 4 is not particularly limited, and an arbitrary device such as a dry development method such as cascade development, one-component conductive toner development, two-component magnetic brush development, or a wet development method can be used. In FIG. 1, the developing device 4 includes a developing tank 41, an agitator 42, a supply roller 43, a developing roller 44, and a regulating member 45, and has a configuration in which toner T is stored inside the developing tank 41. . Further, a replenishing device (not shown) for replenishing the toner T may be attached to the developing device 4 as necessary. The replenishing device is configured to be able to replenish toner T from a container such as a bottle or a cartridge.

  The supply roller 43 is formed from a conductive sponge or the like. The developing roller 44 is made of a metal roll such as iron, stainless steel, aluminum, or nickel, or a resin roll obtained by coating such a metal roll with a silicon resin, a urethane resin, a fluorine resin, or the like. The surface of the developing roller 44 may be smoothed or roughened as necessary.

  The developing roller 44 is disposed between the electrophotographic photoreceptor 1 and the supply roller 43 and is in contact with the electrophotographic photoreceptor 1 and the supply roller 43, respectively. The supply roller 43 and the developing roller 44 are rotated by a rotation drive mechanism (not shown). The supply roller 43 carries the stored toner T and supplies it to the developing roller 44. The developing roller 44 carries the toner T supplied by the supply roller 43 and contacts the surface of the electrophotographic photosensitive member 1.

  The restricting member 45 is formed of a resin blade such as silicon resin or urethane resin, a metal blade such as stainless steel, aluminum, copper, brass, phosphor bronze, or a blade obtained by coating such a metal blade with resin. The regulating member 45 contacts the developing roller 44 and is pressed against the developing roller 44 side with a predetermined force by a spring or the like (a general blade linear pressure is 5 to 500 g / cm). If necessary, the regulating member 45 may be provided with a function of imparting charging to the toner T by frictional charging with the toner T.

  The agitator 42 is rotated by a rotation driving mechanism, and agitates the toner T and conveys the toner T to the supply roller 43 side. A plurality of agitators 42 may be provided with different blade shapes and sizes.

  The type of the toner T is arbitrary, and in addition to the powdery toner, a polymerized toner using a suspension polymerization method, an emulsion polymerization method, or the like can be used. In particular, when a polymerized toner is used, a toner having a small particle diameter of about 4 to 8 μm is preferable, and the toner particles are used in various shapes ranging from a nearly spherical shape to a shape outside the spherical shape on the potato. be able to. The polymerized toner is excellent in charging uniformity and transferability and is suitably used for high image quality.

  The type of the transfer device 5 is not particularly limited, and an apparatus using an arbitrary system such as an electrostatic transfer method such as corona transfer, roller transfer, or belt transfer, a pressure transfer method, or an adhesive transfer method can be used. . Here, it is assumed that the transfer device 5 includes a transfer charger, a transfer roller, a transfer belt, and the like that are disposed to face the electrophotographic photoreceptor 1. The transfer device 5 applies a predetermined voltage value (transfer voltage) having a polarity opposite to the charging potential of the toner T, and transfers the toner image formed on the electrophotographic photosensitive member 1 to a recording paper (paper, medium) P. Is.

  There is no restriction | limiting in particular about the cleaning apparatus 6, Arbitrary cleaning apparatuses, such as a brush cleaner, a magnetic brush cleaner, an electrostatic brush cleaner, a magnetic roller cleaner, a blade cleaner, can be used. The cleaning device 6 is for scraping off residual toner adhering to the photoreceptor 1 with a cleaning member and collecting the residual toner.

The fixing device 7 includes an upper fixing member (fixing roller) 71 and a lower fixing member (fixing roller) 72, and a heating device 73 is provided inside the fixing member 71 or 72. FIG. 1 shows an example in which a heating device 73 is provided inside the upper fixing member 71. Each of the upper and lower fixing members 71 and 72 includes a fixing roll in which a metal base tube such as stainless steel or aluminum is coated with silicon rubber, a fixing roll in which Teflon (registered trademark) resin is coated, and a fixing sheet. A member can be used. Further, each of the fixing members 71 and 72 may be configured to supply a release agent such as silicon oil in order to improve releasability, or may be configured to forcibly apply pressure to each other by a spring or the like.

  When the toner transferred onto the recording paper P passes between the upper fixing member 71 and the lower fixing member 72 heated to a predetermined temperature, the toner is heated to a molten state and cooled after passing through the recording paper. Toner is fixed on P.

  The type of the fixing device is not particularly limited, and a fixing device of any type such as heat roller fixing, flash fixing, oven fixing, pressure fixing, etc. can be provided including those used here.

  In the electrophotographic apparatus configured as described above, an image is recorded as follows. That is, first, the surface (photosensitive surface) of the photoreceptor 1 is charged to a predetermined potential (for example, −600 V) by the charging device 2. At this time, charging may be performed by a DC voltage, or charging may be performed by superimposing an AC voltage on the DC voltage.

  Subsequently, the photosensitive surface of the charged photoreceptor 1 is exposed by the exposure device 3 according to the image to be recorded, and an electrostatic latent image is formed on the photosensitive surface. The developing device 4 develops the electrostatic latent image formed on the photosensitive surface of the photoreceptor 1.

  The developing device 4 thins the toner T supplied by the supply roller 43 with a regulating member (developing blade) 45 and has a predetermined polarity (here, the same polarity as the charging potential of the photosensitive member 1) and the negative polarity. ), And conveyed while being carried on the developing roller 44 to be brought into contact with the surface of the photoreceptor 1.

  When the charged toner T carried on the developing roller 44 comes into contact with the surface of the photoreceptor 1, a toner image corresponding to the electrostatic latent image is formed on the photosensitive surface of the photoreceptor 1. This toner image is transferred onto the recording paper P by the transfer device 5. Thereafter, the toner remaining on the photosensitive surface of the photoreceptor 1 without being transferred is removed by the cleaning device 6.

  After the transfer of the toner image onto the recording paper P, the final image is obtained by passing the fixing device 7 and thermally fixing the toner image onto the recording paper P.

  In addition to the above-described configuration, the image forming apparatus may have a configuration capable of performing, for example, a static elimination process. The neutralization step is a step of neutralizing the electrophotographic photosensitive member by exposing the electrophotographic photosensitive member, and a fluorescent lamp, an LED, or the like is used as the neutralizing device. In addition, the light used in the static elimination process is often light having an exposure energy that is at least three times that of the exposure light.

  The image forming apparatus may be further modified. For example, the image forming apparatus may be configured to perform a pre-exposure process, an auxiliary charging process, or the like, or may be configured to perform offset printing. A full-color tandem system configuration using toner may be used.

EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further in detail, this invention is not limited to these, unless the summary is exceeded. In the examples, “parts” indicates “parts by weight” unless otherwise specified.
<Production Method of Dispersion S1>
A slurry obtained by mixing rutile-type white titanium oxide having an average primary particle size of 40 nm (product name: TTO55N, manufactured by Ishihara Sangyo Co., Ltd.) and 3% by weight of methyldimethoxysilane with respect to the titanium oxide in a ball mill. After drying, the hydrophobized titanium oxide obtained by further washing with methanol and drying was subjected to ball mill dispersion in a mixed solvent of methanol / 1-propanol = 5/2 to obtain a solid content concentration of 33.3% by weight. A dispersion slurry of hydrophobized titanium oxide was obtained.

  The dispersion slurry obtained here is further mixed with methanol, 1-propanol, toluene and nylon pellets represented by the following structural formula, and stirred while warming to dissolve the nylon pellets, By performing ultrasonic dispersion treatment, finally, methanol / 1-propanol / toluene = 5/2/3 (weight ratio) as a solvent, and hydrophobized titanium oxide / nylon = 3/1 (weight ratio) as a solid content. ), A dispersion having a solid content concentration of 24% was prepared, and this was designated as dispersion S1.

<Production Method of Dispersion S2>
Black titanium oxide (Ako Kasei Co., Ltd., product name Tilac) having an electrical resistance of 120 Ω · cm, blackness (L value) of 15, and primary particle diameter of 0.2 to 0.4 μm as observed by an electron microscope. D (fine particle type)) was ball mill dispersed in a mixed solvent of methanol / 1-propanol = 5/2 to obtain a black titanium oxide dispersed slurry having a solid content concentration of 33.3% by weight. Furthermore, methanol, 1-propanol, toluene, and nylon pellets are added, stirred and mixed while heating, the nylon pellets are dissolved, and then subjected to ultrasonic dispersion treatment to finally obtain a solid content concentration. A dispersion of 24% by weight of black titanium oxide / nylon = 3/1 was prepared, and this was designated as dispersion S2.
<Production Method of Dispersion S3>
In the same manner as in the preparation of the dispersion S1, the hydrophobized white titanium oxide was ball milled in a methanol / 1-propanol mixed solvent to obtain a hydrophobized white titanium oxide dispersed slurry. Further, a black titanium oxide dispersion slurry was prepared in the same manner as the dispersion S2.

Mix the two obtained dispersion slurries, add methanol, 1-propanol, toluene, nylon pellets, stir and mix while warming to dissolve the nylon pellets, then ultrasonic dispersion treatment Finally, a dispersion of hydrophobized white titanium oxide / black titanium oxide / nylon = 2.625 / 0.375 / 1 having a solid content concentration of 24% by weight was prepared, and this was designated as dispersion S3. did.
<Production Method of Dispersion S4>
In the same manner as in the preparation of the dispersion liquid S2, black oxidation in which the electrical resistance of the 9.8 MPa compact is 20 Ω · cm, the blackness (L value) is 17, and the primary particle diameter is 0.03 to 0.1 μm by observation with an electron microscope. Titanium (Ako Kasei Co., Ltd., product name Tilac D (ultrafine particle type)) was ball milled in a mixed solvent of methanol / 1-propanol to obtain a dispersed slurry of black titanium oxide. Furthermore, methanol, 1-propanol, toluene, and nylon pellets are added, stirred and mixed while heating, the nylon pellets are dissolved, and then subjected to ultrasonic dispersion treatment to finally obtain a solid content concentration. A dispersion of 24% by weight of black titanium oxide / nylon = 3/1 was prepared, and this was designated as dispersion S4.
<Production Method of Dispersion S5>
The hydrophobized white titanium oxide was subjected to ball mill dispersion in a methanol / 1-propanol mixed solvent in the same manner as in the preparation of the dispersion S1 to obtain a dispersed slurry of the hydrophobized white titanium oxide. Similarly, a dispersion slurry of silica spherical particles having an average particle diameter of 0.28 ± 0.03 μm (Nippon Shokubai Co., Ltd., product name: Seahoster KE-P30) was prepared. Mix the two obtained dispersion slurries, add methanol, 1-propanol, toluene, nylon pellets, stir and mix while warming to dissolve the nylon pellets, then ultrasonic dispersion treatment By carrying out the process, a dispersion liquid of hydrophobized white titanium oxide / silica spherical particles / nylon = 3/1/1 having a solid content concentration of 24% by weight was finally prepared, and this was designated as dispersion liquid S5.
<Example 1>
Dispersion S2 was dip-coated on an aluminum cylinder having an outer diameter of 30 mm, a length of 357 mm, and a wall thickness of 0.75 mm with a mirror-finished surface, and an undercoat layer was provided so that the dry film thickness was 2 μm. .

Next, 10 parts of oxytitanium phthalocyanine, which exhibits a characteristic peak at a black angle 2θ (± 0.2 °) of 27.3 ° in a powder X-ray spectrum pattern by CuKα ray, polyvinyl butyral (Electrochemical Industry Co., Ltd.) Product, trade name # 6000-C) and 500 parts of 1,2-dimethoxyethane were mixed, and pulverized and dispersed by a sand grind mill. This dispersion was applied by dip coating on the undercoat layer of the previous aluminum cylinder, and a charge generation layer was provided so that the dry film thickness was 0.3 g / m ² (about 0.3 μm).

  Next, 100 parts of a copolymerized polycarbonate represented by the following structural formula

50 parts of an arylamine compound represented by the following structural formula

8 parts of a hindered phenol compound represented by the following structural formula

Was coated with 560 parts of a mixed solvent of tetrahydrofuran: toluene = 8/2 on the charge generation layer by dip coating to form a charge transfer layer so that the film thickness after drying was 25 μm. The photoreceptor thus obtained is designated as A1.
<Example 2>
A photoconductor was obtained in the same manner as in Example 1 except that the dispersion S2 was dip coated on the aluminum cylinder used in Example 1 and an undercoat layer was provided so that the dry film thickness was 4 μm. It was. The photoreceptor thus obtained is designated A2.
<Example 3>
A photoconductor was obtained in the same manner as in Example 1 except that the dispersion S2 was dip coated on the aluminum cylinder used in Example 1 and an undercoat layer was provided so that the dry film thickness was 6 μm. It was. The photoreceptor thus obtained is designated as A3.
<Example 4>
A photoconductor was obtained in the same manner as in Example 1 except that the dispersion S3 was dip-coated on the aluminum cylinder used in Example 1 and an undercoat layer was provided so that the dry film thickness was 4 μm. It was. The photoreceptor thus obtained is designated as A4.
<Example 5>
A photoconductor was obtained in the same manner as in Example 1 except that the dispersion S4 was dip-coated on the aluminum cylinder used in Example 1 and an undercoat layer was provided so that the dry film thickness was 4 μm. It was. The photoreceptor thus obtained is designated as A5.
<Comparative Example 1>
A photoreceptor is obtained in the same manner as in Example 1 except that the dispersion S1 is dip-coated on the aluminum cylinder used in Example 1 and an undercoat layer is provided so that the dry film thickness is 2 μm. It was. The photoreceptor thus obtained is designated B1.
<Comparative example 2>
A photoconductor was obtained in the same manner as in Example 1 except that the dispersion S5 was dip-coated on the aluminum cylinder used in Example 1 and an undercoat layer was provided so that the dry film thickness was 4 μm. It was. The photoreceptor thus obtained is designated B2.
<Evaluation>
Next, these electrophotographic photoreceptors are mounted on an electrophotographic characteristic evaluation apparatus (basic and applied electrophotographic technology, edited by the Electrophotographic Society, Corona, pages 404 to 405) prepared according to the Electrophotographic Society standard. When mounted on a photoconductor characteristic measuring device and charged so that the surface potential under a 25 ° C./50% environment (hereinafter sometimes referred to as NN environment) is −700 V, the light is irradiated at 780 nm. Half-exposure amount (hereinafter sometimes referred to as E1 / 2), potential holding ratio after being charged to -700 V and left for 5 seconds (hereinafter also referred to as DDR), residual after irradiation with LED light of 660 nm The potential (hereinafter sometimes referred to as Vr) was measured. The electrical property evaluation results are shown in Table 1.

  Each of the photoreceptors A1 to A5 of Examples 1 to 5 and the photoreceptors B1 and B2 of Comparative Examples 1 and 2 exhibited good electrical characteristics.

Next, coating liquids S1 to S5 were applied on the polyester film with a wire bar so that the film thickness after drying was as shown in Table 2 to form an undercoat layer. The transmittance at 780 nm of these undercoat layers was measured using a spectrophotometer (Shimadzu Corporation, product name UV-3100PC). In addition, a standard white plate (BaSO ₄ powder) at 780 nm of these undercoat layers
Was measured using an integrating sphere attachment device (Shimadzu Corporation, product name ISR-3100). Each result is shown in Table 4.

  In the undercoat layer composed of S2 to S4 containing black titanium oxide, both transmittance and diffuse reflectance were 15% or less. On the other hand, in the undercoat layer formed by applying the coating liquid S1 using only hydrophobized titanium oxide, the diffuse reflectance was 15% or less, but the transmittance was large. Moreover, in the undercoat layer formed by applying the hydrophobized titanium oxide and the coating liquid S5 using silica spherical particles, both the transmittance and the diffuse reflectance were 15% or more.

  Next, the photoconductors A1 to A4 of Examples 1 to 5 and the photoconductors B1 and B2 of Comparative Examples 1 and 2 were mounted on a commercially available monochrome laser printer (LASER JET 5000 PCL6 manufactured by Hured Packard) under an NN environment. Then, five types of halftone images (from the thinnest HT1 to the darkest HT5) were formed in the ProRes 1200-highest quality mode (1200 dpi mode), and image evaluation was performed. The case where no interference fringes could be confirmed with the naked eye was marked with ○, and the case where interference fringes were recognized was marked with ×. The results are shown in Table 3.

  In the photoreceptors A1 to A5 of the example, no interference fringe pattern was observed in the halftone images of any density, and a good image could be formed. However, in the photoreceptor B1 of the comparative example, any density was obtained. The interference fringe pattern was clearly observed in the halftone image. In the photoconductor B2 of the comparative example, interference fringes were observed in the dark halftone image, although interference fringes were not confirmed in the thin halftone image.

  From the result of image evaluation and the result of measurement by a spectrophotometer, it was found that an electrophotographic photosensitive member having an undercoat layer containing black titanium oxide can provide a good image in which no interference fringe pattern is generated.

On the undercoat layer of the electrophotographic photosensitive member, the electrical resistance value of the 9.8 MPa compact is 10 ⁻¹ to 10 ⁴ Ω ·
By including a black inorganic compound having a size of cm, it is possible to provide an electrophotographic photosensitive member that can be applied to electrophotographic apparatuses such as printers, facsimiles, and copiers that use coherent light as a light source.

1 is a schematic diagram illustrating a main configuration of an embodiment of an image forming apparatus including an electrophotographic photosensitive member of the present invention.

Explanation of symbols

1 Photoconductor 2 Charging device (charging roller)
DESCRIPTION OF SYMBOLS 3 Exposure apparatus 4 Developing apparatus 5 Transfer apparatus 6 Cleaning apparatus 7 Fixing apparatus 41 Developing tank 42 Agitator 43 Supply roller 44 Developing roller 45 Control member 71 Upper fixing member (fixing roller)
72 Lower fixing member (fixing roller)
73 Heating device T Toner P Recording paper (paper, medium)

Claims (7)

In an electrophotographic photosensitive member having an undercoat layer and a photosensitive layer on a conductive substrate, the undercoat layer comprises a black inorganic compound having an electrical resistance of 9.8 MPa green compact of 1 to 10 ⁴ Ω · cm. An electrophotographic photosensitive member, comprising: The electrophotographic photosensitive member according to claim 1, wherein the black inorganic compound is black titanium oxide. The electrophotographic photosensitive member according to claim 1, wherein the undercoat layer has a transmittance and diffuse reflectance at 780 nm of 15% or less. The electrophotographic photosensitive member according to claim 1, wherein a primary particle diameter of the black inorganic compound is 0.5 μm or less. The electrophotographic photosensitive member according to claim 1, wherein the total amount of metal compound particles contained in the undercoat layer is 2 to 4 parts by weight with respect to 1 part by weight of the binder resin. The electrophotographic photosensitive member according to claim 1, wherein the undercoat layer has a thickness of 1 μm to 18 μm. An image forming apparatus using the electrophotographic photosensitive member according to claim 1.

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