JP2004302462A - Electrophotographic photoreceptor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor including an undercoat layer whose electrical properties also including a recursive property are good in all environments from a low temperature and low humidity environment to a high temperature and high humidity environment even when the thickness of the undercoat layer is made larger, with respect to an electrophotographic photoreceptor including an undercoat layer and a photosensitive layer. <P>SOLUTION: The electrophotographic photoreceptor includes an undercoat layer containing metal compound particles and a binder resin and a photosensitive layer on a conductive substrate, wherein the metal compound particles comprise metal compound particles made conductive by a treatment of making them conductive. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an electrophotographic photoreceptor having at least an undercoat layer and a photosensitive layer, which has good electric characteristics and does not cause image defects.

Conventionally, inorganic photoconductive materials such as selenium, selenium-tellurium alloy, arsenic selenide, and cadmium sulfide have been widely used for electrophotographic photoreceptors, but in recent years, organic photoconductors which have low pollution and are easy to manufacture have been used. An electrophotographic photoreceptor using a photoconductive material of the above type for a photosensitive layer has become mainstream.
As a form of the photosensitive layer, in addition to a so-called dispersion type or single-layer type photosensitive layer in which particles of a charge generation material are dispersed in a charge transport medium containing a charge transport material, a charge generation layer containing a charge generation material may be used. A so-called laminated type photosensitive layer in which a charge transport layer containing a charge transport material is laminated is known. In particular, a laminated photoreceptor having a charge generation layer and a charge transfer layer in which a function of generating a charge by absorbing light and a function of transporting the generated charge are separated is mainly used. These photoconductors are widely used in the fields of copying machines, laser printers and the like.

An electrophotographic photoreceptor has a basic structure in which a photosensitive layer is formed on a conductive support. It is known to provide an undercoat layer 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.
As an undercoat layer in which an inorganic material is dispersed in a polyamide resin, titanium oxide and tin oxide, which are metal oxide particles having a band gap of 2 to 4 eV, are dispersed in 8-nylon (for example, see Patent Document 1). One in which alumina-treated titanium oxide is dispersed in a polyamide resin is known (for example, see Patent Document 2). Further, for the purpose of improving electric characteristics without disturbing image characteristics, titanium oxide particles having an average primary particle diameter of 100 nm or less are dispersed in a polyamide resin (for example, see Patent Document 3). For the purpose of improving the characteristics, a dispersion of metal oxide particles treated with an organosilicon compound in a binder resin such as a polyamide resin has been proposed (for example, see Patent Document 4).

On the other hand, one of the roles of the undercoat layer is to cover the defects of the support, but it is known that increasing the thickness of the undercoat layer is effective for increasing the concealment effect. Have been. In recent years, in the trend of downsizing of electrophotographic apparatuses, apparatuses adopting a contact charging method as a charging method have been increasing. In this charging system, particularly, dielectric breakdown (leakage) of the photoreceptor causes a problem of causing image defects. It is known that increasing the thickness of the undercoat layer is also effective in suppressing this dielectric breakdown.
JP-A-62-280864 JP-A-2-181158 JP-A-10-069116 JP 11-015183 A

  It is desired to increase the thickness of the undercoat layer in order to conceal the defects of the support and prevent dielectric breakdown of the photoconductor. However, the electrophotographic photoreceptor having a thick undercoat layer has a drawback that the potential remaining on the photoreceptor tends to increase due to repeated use, and in order to overcome the problem, for example, An undercoat layer in which titanium oxide particles having an average primary particle diameter of 100 nm or less measured by a transmission electron microscope are dispersed, or an undercoat layer in which metal oxide particles subjected to a hydrophobic treatment with an organic silicon compound or the like are dispersed. Has been used.

  However, in the undercoat layer in which titanium oxide particles having an average primary particle diameter of 100 nm or less are dispersed, the electric characteristics are improved under the environment of normal temperature and normal humidity, but the residual potential is easily increased under the environment of high temperature and high humidity. On the other hand, the undercoat layer in which metal oxide particles hydrophobized with an organosilicon compound or the like are dispersed has improved characteristics in a high-temperature and high-humidity environment, but has a low temperature and a low humidity. There is a problem that the electrical characteristics under the environment of the above are deteriorated.

  The present invention, in an electrophotographic photoreceptor having at least an undercoat layer and a photosensitive layer, even when the thickness of the undercoat layer is increased, in all environments from a low-temperature low-humidity environment to a high-temperature high-humidity environment, An object of the present invention is to provide an electrophotographic photoreceptor having an undercoat layer having good electric characteristics including repetition characteristics. Another object of the present invention is to provide an electrophotographic apparatus provided with a photoreceptor having good electric characteristics including repetition characteristics in all environments from a low-temperature and low-humidity environment to a high-temperature and high-humidity environment. It is in.

  The present inventors have found that the above problem can be solved by including a metal compound particle subjected to a conductive treatment in an undercoat layer, and have reached the present invention. That is, the present invention relates to an electrophotographic photoreceptor having a photosensitive layer and an undercoat layer containing a metal compound particle and a binder resin on a conductive substrate, wherein the metal compound particle is a conductive layer. Characteristic electrophotographic photosensitive member.

  The electrophotographic photoreceptor having the undercoat layer containing the metal compound particles subjected to the electroconductivity treatment of the present invention is not affected by defects such as a support, prevents dielectric breakdown, and has a good electric charge even in various environments. Show characteristics.

Hereinafter, embodiments of the present invention will be described in detail. However, the description of the constituent elements described below is a representative example of the embodiments of the present invention, and may be appropriately modified without departing from the spirit of the present invention. can do.
The photoreceptor of the present invention has an undercoat layer on a conductive substrate, and the undercoat layer contains metal compound particles subjected to a conductivity treatment. The undercoat layer is formed between the conductive support and the photosensitive layer.

  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, applying the obtained coating solution on a conductive support, and drying. In the coating solution, as long as the properties of the undercoat layer and the dispersion stability of the coating solution are not deteriorated, if necessary, particles other than metal oxides, charge transport molecules, antioxidants, dispersants, leveling agents, Other additives and the like may be added.

The undercoat layer may be applied by any coating method as long as it can be applied to a certain degree, but is generally applied by dip coating, spray coating, nozzle coating, or the like.
<Conducted metal compound particles>
Examples of the method for making the metal compound particles conductive include metal powder or metal flakes such as carbon black, graphite, gold, silver, palladium, platinum, copper, nickel, and aluminum, carbon fiber, metallized glass fiber, stainless steel fiber, and aluminum fiber. For example, a method of coating the surface of the particles to be conductive with a powder of a conductive fiber such as indium oxide, tin oxide, or a transparent conductive filler obtained by doping tin oxide with a metal element such as antimony or indium is used. Among them, the use of tin oxide powder doped with a metal element such as antimony or indium is preferable because of easy control of powder resistance.

  Examples of the conductive particles include metal oxides such as titanium oxide, zinc oxide, alumina, and silica; metal sulfates such as barium sulfate; metal sulfides such as zinc sulfide; and aluminum borate whiskers. Among them, metal oxides such as titanium oxide, zinc oxide, alumina and silica are preferable. Among them, titanium oxide is particularly preferable in terms of cost, dispersibility, and the fact that the flow of charges generated in the charge generation layer is not hindered.

  If the average primary particle size of the particles to be made conductive is too large, the dispersion uniformity of the particles is deteriorated. Therefore, the average primary particle size is usually 1 μm or less, preferably 0.5 μm or less. On the other hand, if the particle size is too small, aggregation of particles and the like occur, which is not preferable. Examples of the shape of the powder to be conductive include a sphere, a needle, a spindle, and the like, and a sphere is preferred because it is most easily controlled in terms of charging characteristics.

  The powder resistance value of the metal compound particles subjected to the conductivity treatment is not particularly limited, but if it is too small, the change in the volume resistivity of the undercoat layer with respect to the content becomes large, and it becomes difficult to produce a photoreceptor. An 8 MPa green compact, usually 1 Ωcm or more, preferably 3 Ωcm or more, more preferably 5 Ωcm or more is used. Further, if the powder resistance of the conductive oxide particles becomes too large, it is necessary to contain a large amount of particles in order to adjust the volume resistivity of the undercoat layer to a desired value. Therefore, a 9.8 MPa green compact, usually 100 Ωcm or less, preferably 50 Ωcm or less, more preferably 30 Ωcm or less is used.

  In the present invention, the amount of the conductive particles subjected to the conductivity treatment contained in the undercoat layer is related to the powder resistance value of the oxide particles subjected to the conductivity treatment to be used. It is appropriately adjusted in order to obtain a desired one, but it is usually preferably 0.1 to 20% by weight, particularly preferably 1 to 15% by weight, more preferably 2 to 10% by weight based on all particles in the undercoat layer. %.

In addition, as the oxide particles subjected to the conductivity treatment, one kind may be used, or a mixture of two or more kinds may be used. However, in the case of a mixture of two or more kinds, there is a possibility that aggregation of particles occurs or a trap of electric charge is generated, so that one kind is preferably used.
<Metal oxide particles that have not been rendered conductive>
The undercoat layer in the present invention preferably contains metal oxide particles that have not been subjected to a conductive treatment, separately from the metal compound particles that have been subjected to a conductive treatment. As the metal oxide particles, n-type (electron transporting) particles are preferable. Specific examples of such metal oxides include titanates such as strontium titanate, calcium titanate, and barium titanate; titanium oxide; metal oxides such as nickel oxide, zinc oxide, and cobalt oxide; Solid solution; titanium oxide doped with a metal element such as niobium, antimony, tungsten, indium, nickel, iron, silicon and the like. Among these, titanium oxide particles are preferable from the viewpoint of price and stability as a compound.

These metal oxide particles are particles having an average primary particle diameter of usually 100 nm or less, preferably 60 nm, from the viewpoint of the dispersion stability of the coating liquid for forming an undercoat layer and the electric characteristics such as residual potential. Hereinafter, those having a thickness of 50 nm or less, more preferably 10 nm or more, and preferably 20 nm or more are used.
In order to stabilize a dispersion in which particles are dispersed in a coating liquid for forming an undercoat layer, the metal oxide particles are preferably subjected to a hydrophobic treatment. The method of hydrophobizing treatment is not particularly limited as long as it can be hydrophobized, but saturated aliphatic carboxylic acids such as octadecanoic acid and dodecanoic acid; polyols such as 1,1,1-trimethylolethane and pentaerythritol; Coupling agents, aluminum-based coupling agents, treatment with an organometallic compound such as silicone, and the like can be given. Among them, it is preferable to treat with a silicone oil such as dimethylpolysiloxane or methylhydrogenpolysiloxane; an organosilicon compound such as a silane treating agent such as methyldimethoxysilane and a silane coupling agent. The treatment with a silane treating agent represented by the general formula is preferred because it has good reactivity with the metal oxide.

(In the formula, R ¹ and R ² each independently represent a methyl group or an ethyl group. R ³ represents a group selected from the group consisting of a methyl group, an ethyl group, a methoxy group and an ethoxy group.)
The outermost surfaces of these hydrophobically treated particles have been treated with the above-mentioned hydrophobizing agent, but may be previously treated with a hydrophilic treating agent such as aluminum oxide.
<Binder resin for undercoat layer>
As a binder resin for forming the undercoat layer, a resin material such as polyvinyl acetal, a polyamide resin, a phenol resin, a polyester resin, an epoxy resin, a polyurethane resin, a polyacrylic acid resin, and a conductive resin for the purpose of improving electrical characteristics are used. I can do it.

  Among them, a polyamide resin which has excellent adhesion to a support and has low solubility in a solvent used for a charge generation layer coating solution is preferred. Among them, a copolymer polyamide resin having a diamine component represented by the following general formula as a component is particularly preferable.

(A and B each independently represent a cyclohexyl ring which may have a substituent, and R ⁴ and R ⁵ each independently represent hydrogen, an alkyl group, an alkoxy group, or an aryl group.)
The ratio of the particles to the binder resin can be arbitrarily selected, but from the viewpoint of the stability and characteristics of the coating solution, the ratio is preferably 0.5 parts by weight to 6 parts by weight with respect to 1 part by weight of the binder resin. Particular to 4 parts by weight is particularly preferred.

  If the thickness of the undercoat layer is too small, the effect on local charging failure is not sufficient, and if too thick, on the other hand, the residual potential increases, or the adhesion strength between the conductive substrate and the photosensitive layer decreases. Cause. The thickness of the undercoat layer of the present invention is usually at least 0.1 μm, preferably at least 1 μm, more preferably at least 3 μm, particularly preferably at least 5 μm, usually at most 20 μm, preferably at most 15 μm, more preferably at most 10 μm. Used in:

When the volume resistivity of the undercoat layer is too low, the charge easily moves and the photoconductor is not charged. Therefore, the volume resistivity is preferably 1 × 10 ¹⁰ Ωcm or more. Since it leads to accumulation, it is preferably used at 1 × 10 ¹³ Ωcm or less.
<Support>
As the conductive support used in the present invention, as the conductive support, any of those used in well-known electrophotographic photosensitive members can be used. Specifically, for example, aluminum, stainless steel, copper, a drum made of a metal material such as copper, a laminate of these metal foils, a deposited material, or a surface thereof, aluminum, copper, palladium, tin oxide, indium oxide, etc. And an insulating support such as a polyester film or paper provided with a conductive layer. Further, plastic films, plastic drums, paper, paper tubes, and the like, which are subjected to conductive treatment by applying a conductive substance such as metal powder, carbon black, copper iodide, and polymer electrolyte together with a suitable binder, may be used. Further, a plastic sheet or drum containing a conductive substance such as a metal powder, carbon black, or carbon fiber to become conductive may be used. Further, plastic films and belts which have been subjected to a conductive treatment with a conductive metal oxide such as tin oxide or indium oxide can be used.

Among them, an endless pipe made of metal such as aluminum is a preferable support. The endless pipe made of aluminum or its alloy is formed by extrusion, drawing, ironing or the like. The molded product may be used as it is, or may be further processed by cutting, grinding, polishing or the like. The surface of the conductive support can be subjected to various treatments such as an oxidation treatment and a 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 in which a charge generating substance, a charge transport substance, and a binder resin are contained in a single layer (hereinafter, may be referred to as a single-layer photosensitive layer or a dispersed photosensitive layer). Alternatively, a laminated structure in which a charge generating layer containing a charge generating substance and a charge transporting layer containing a charge transporting substance are laminated (hereinafter, sometimes referred to as a laminated photosensitive layer) may be used.

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 generation material is a main component and dispersed in a binder resin. A material in which a charge generating substance and a charge transporting substance are mainly dispersed in a binder resin is used. When the photosensitive layer has a laminated structure, a charge generation layer and a charge transport layer are laminated on the undercoat layer.
<Charge generating substance>
As the charge generating substance, various organic pigments and dyes such as phthalocyanine, azo, perylene, quinacridone, polycyclic quinone, pyrylium salt, indigo, thioindigo, anthantrone, pyranthrone and cyanine can be used. Among them, metals such as metal-free phthalocyanines, copper, indium, gallium, tin, titanium, zinc, vanadium, and silicon, or oxides, hydroxides, and chloride-coordinated phthalocyanines, monoazo, bisazo, trisazo, and polyazos And azo pigments and perylene pigments.

  Among these charge generating materials, metal-free and metal-containing phthalocyanines can provide a photoreceptor with high sensitivity to laser light of a relatively long wavelength of 500 nm to 800 nm, LED, or the like. Azo pigments such as monoazo, bisazo, and trisazo are excellent in that they have sufficient sensitivity to white light, laser light having a relatively short wavelength of 300 to 500 nm, LED, or the like, and are preferable.

Among the phthalocyanines, so-called D-type oxytitanium phthalocyanine, in which the black angle (2θ ± 0.2 °) of the X-ray diffraction spectrum with respect to the CuKα characteristic X-ray shows a main diffraction peak at 27.3 °, 9. So-called oxytitanium phthalocyanine type A, showing main diffraction peaks at 3 °, 13.2 °, 26.2 ° and 27.1 °, 9.2, 14.1, 15.3, 19.7, 27.1 Dihydroxysilicon phthalocyanine having a main diffraction peak at ゜, a main diffraction peak at 8.5 °, 12.2 °, 13.8 °, 16.9 °, 22.4 °, 28.4 ° and 30.1 ° The indicated dichlorotin phthalocyanine, 7.5%, 9.9%, 12.5%, 16.3%, 18.6%, 25.1% and 28.3.
Preference is given to hydroxygallium phthalocyanine, which exhibits major diffraction peaks at ゜, and chlorogallium phthalocyanine, which exhibits diffraction peaks at 7.4, 16.6, 25.5 and 28.3 °.

The charge generation layer of the laminated photosensitive layer can be obtained by applying and drying a coating solution obtained by dissolving or dispersing fine particles of these substances and a binder polymer in a solvent.
As the binder resin used for the charge generation layer, styrene, vinyl acetate, vinyl chloride, acrylic acid ester, methacrylic acid ester, vinyl alcohol, polymers and copolymers of vinyl compounds such as ethyl vinyl ether, polyvinyl acetal, polycarbonate, polyester, Examples include polyamide, polyurethane, cellulose ether, phenoxy resin, silicon resin, epoxy resin and the like. 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.

  Examples of the solvent used for the coating solution for forming the charge generation layer include alcohols such as methanol and propanol, ethers such as 1,4-dioxane and 1,2-dimethoxyethane, methyl ethyl ketone, cyclohexanone, and 4-methoxy-4-. Ketones, such as methylpentanone-2, and hydrocarbons, such as toluene. One of these solvents may be used alone, or a mixture of two or more solvents may be used. Among these solvents, 1,2-dimethoxyethane and 4-methoxy-4-methylpentanone-2 are preferred because of the crystal stability of the pigment.

The ratio between the charge generating substance and 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 per 100 parts by weight of the charge generating substance.
Further, the charge generation layer may be a deposited film of the above charge generation substance.
The thickness of the charge generation layer is 0.05 to 5 μm, preferably 0.1 to 2 μm.
<Charge transport material>
As the charge transport substance, a high molecular compound such as polyvinyl carbazole, polyvinyl pyrene, and polyacenaphthylene, or a low molecular compound such as various pyrazoline derivatives, oxazole derivatives, hydrazone derivatives, stilbene derivatives, butadiene derivatives, and arylamine derivatives can be used. Today, low molecular weight compounds of hydrazone derivatives, stilbene derivatives, butadiene derivatives and hydrazone derivatives are preferably used.

  The charge transport layer in the laminated photosensitive layer can be obtained by applying and drying a coating solution obtained by dissolving the charge transport material and the binder polymer in a solvent on the charge generation layer. As the binder polymer, a polymer which has good compatibility with the above-described charge transporting substance and does not crystallize or phase-separate the charge transporting substance after forming the coating film is preferable. Examples thereof include polymers and copolymers of vinyl compounds such as styrene, vinyl acetate, vinyl chloride, acrylic acid ester, methacrylic acid ester, vinyl alcohol, and ethyl vinyl ether, polyvinyl acetal, polycarbonate, polyester, polysulfone, and polyphenylene oxide. , Polyurethane, cellulose ester, cellulose ether, phenoxy resin, silicon resin, epoxy resin, and a polymer in which the above-described charge transfer material of a low molecular compound is introduced into a main chain and / or a side chain.

Among them, polycarbonate resins are preferably used in view of mechanical properties such as abrasion resistance and compatibility of the charge transport material and the binder polymer in a solution.
The ratio between the binder resin and the charge transport material is usually at least 10 parts by weight, preferably at least 20 parts by weight, particularly preferably at least 30 parts by weight, because if the amount of the charge transport material is too small relative to the binder resin, the electrical properties deteriorate. Used in more than one part. Further, when the amount of the charge transporting substance is too large, the hardness of the charge transporting layer is reduced, and the wear during use is increased, and the surface is damaged and image defects are easily generated. Therefore, usually 200 parts by weight or less, preferably 100 parts by weight. Or less, particularly preferably 70 parts by weight or less.

The thickness of the charge transport layer is usually in the range of 10 to 50 μm, preferably 13 to 35 μm.
An electron withdrawing compound may be added to the charge transport layer as needed. Examples of the electron-withdrawing compound include cyano compounds such as tetracyanoquinodimethane, dicyanoquinomethane, aromatic esters having a dicyanoquinovinyl group, nitro compounds such as 2,4,6-trinitrofluorenone, and condensation of perylene and the like. 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, a cyano compound, a nitro compound, a condensed polycyclic aromatic compound, a diphenoquinone derivative, a metal complex of substituted and unsubstituted salicylic acid, a metal salt of substituted and unsubstituted salicylic acid, a metal complex of aromatic carboxylic acid, and a metal complex of aromatic carboxylic acid It is preferable to use a metal salt.

The photosensitive layer of the electrophotographic photoreceptor of the present invention is formed of a plasticizer, an antioxidant, and the like in order to improve film formability, flexibility, applicability, mechanical strength, slipperiness, and gas resistance such as ozone and NOx. Various additives such as an ultraviolet absorber, inorganic particles, resin particles, wax, silicone oil, and a leveling agent may be contained.
In the single-layer type photosensitive layer, a mixture in which the above-mentioned charge generating substance, charge transporting substance, various additives and binder polymer are mixed and dispersed is used.
<Other functional layers>
An overcoat layer may be used on the photosensitive layer in order to improve the mechanical properties and the resistance to gas such as ozone and NOx. Further, if necessary, it may have an adhesive layer, an intermediate layer, a transparent insulating layer and the like.

Further, an intermediate layer may be provided between the undercoat layer and the photosensitive layer, or between the undercoat layer and the conductive substrate. However, the undercoat layer of the present invention alone has an electrical characteristic upon repetition. In addition, since it shows good electric characteristics, it is preferable not to provide such an intermediate layer in terms of productivity and cost.
<Layer forming method>
The undercoat layer, photosensitive layer and other functional layers are formed by applying a coating solution on a conductive support by a spray method, a spiral method, a ring method, an immersion method or the like.

Examples of the spray used in the spraying 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 atomization type electrostatic spray described in Japanese Patent Laid-Open Publication No. 1-805198 is preferable.
Examples of the spiral method include a method using a liquid injection coating machine or a curtain coating machine described in JP-A-52-119651, and a method of applying a paint from a fine opening described in JP-A-1-219666. And a method using a multi-nozzle body disclosed in JP-A-3-193161.
<Image forming apparatus>
Next, an embodiment of an image forming apparatus using the electrophotographic photoreceptor of the present invention (image forming apparatus of the present invention) will be described with reference to FIG. However, the embodiments are not limited to the following description, and can be arbitrarily modified and implemented 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 exposing device 3, and a developing device 4, and further includes 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. 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 2 shows a photoconductor in a shape of a circle. A charging device 2, an exposure device 3, a developing device 4, a transfer device 5, and a cleaning device 6 are arranged 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. Examples of the charging device include a corona charging device such as a corotron and a scorotron, and a contact charging device such as a direct charging device (contact charging device) for charging a direct charging member to which a voltage is applied by bringing the member into contact with the surface of the photoreceptor. Often used. Examples of the direct charging unit include a contact charging device such as a charging roller and a charging brush. FIG. 1 illustrates a roller-type charging device (charging roller) as an example of the charging device 2. As the direct charging means, either charging with air discharge or injection charging without air discharge is possible. In addition, as the voltage applied at the time of charging, a DC voltage alone may be used, or an AC may be superimposed on a DC.

  The type of the exposure device 3 is not particularly limited as long as it can expose the electrophotographic photosensitive member 1 to form an electrostatic latent image on the photosensitive surface of the electrophotographic photosensitive member 1. Specific examples include halogen lamps, fluorescent lamps, lasers such as semiconductor lasers and He-Ne lasers, and LEDs. Further, the exposure may be performed by a photoconductor internal exposure method. The light at the time of exposure is arbitrary, and for example, the exposure may be performed using monochromatic light having a wavelength of 780 nm, monochromatic light having a wavelength slightly shorter than 600 nm to 700 nm, or monochromatic light having a shorter 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 developing system such as a cascade developing, a one-component insulating toner developing, a one-component conductive toner developing, a two-component magnetic brush developing, or a wet developing system is used. be able to. 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 the toner T is stored in the developing tank 41. . Further, a replenishing device (not shown) for replenishing the toner T may be attached to the developing device 4 as needed. The replenishing device is configured to be able to replenish the 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 of iron, stainless steel, aluminum, nickel, or the like, or a resin roll in which such a metal roll is coated with a silicon resin, a urethane resin, a fluorine resin, or the like. The surface of the developing roller 44 may be subjected to smoothing or roughening if necessary.
The developing roller 44 is disposed between the electrophotographic photosensitive member 1 and the supply roller 43, and is in contact with the electrophotographic photosensitive member 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 regulating member 45 is formed by a resin blade such as a silicone resin or a urethane resin, a metal blade such as stainless steel, aluminum, copper, brass, phosphor bronze, or the like, or a blade in which such a metal blade is coated with a resin. The regulating member 45 is in contact with the developing roller 44 and is pressed against the developing roller 44 by a predetermined force with a spring or the like (a general blade linear pressure is 5 to 500 g / cm). If necessary, the regulating member 45 may have a function of charging the toner T by frictional charging with the toner T.

The agitator 42 is rotated by a rotation drive 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, sizes, and the like.
The type of the transfer device 5 is not particularly limited, and any type of device such as an electrostatic transfer method such as corona transfer, roller transfer, and belt transfer, a pressure transfer method, and 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 which are arranged to face the electrophotographic photosensitive member 1. The transfer device 5 applies a predetermined voltage value (transfer voltage) having a polarity opposite to the charged potential of the toner T, and transfers the toner image formed on the electrophotographic photosensitive member 1 to a recording paper (paper, medium) P. Things.

  The cleaning device 6 is not particularly limited, and any cleaning device such as a brush cleaner, a magnetic brush cleaner, an electrostatic brush cleaner, a magnetic roller cleaner, and a blade cleaner can be used. The cleaning device 6 is configured to scrape residual toner adhered to the photoreceptor 1 with a cleaning member and collect the residual toner. However, when the toner remaining on the photoreceptor surface is small or almost nonexistent, the cleaning device 6 may be omitted.

  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. For the upper and lower fixing members 71 and 72, use is made of a known heat fixing member such as a fixing roll in which a metal tube made of stainless steel, aluminum or the like is coated with silicon rubber, a fixing roll coated with a fluorine resin, and a fixing sheet. be able to. Further, the fixing members 71 and 72 may be configured to supply a release agent such as silicone oil in order to improve the 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, cooled after passing through, and cooled. The toner is fixed on P.
The type of the fixing device is not particularly limited, and a fixing device of any type, such as a fixing device used here, a heat roller fixing device, a flash fixing device, an oven fixing device, and a pressure fixing device, may be provided.

In the electrophotographic apparatus configured as described above, an image is recorded as follows. That is, first, the surface (photosensitive surface) of the photoconductor 1 is charged to a predetermined potential (for example, −600 V) by the charging device 2. At this time, the battery may be charged by a DC voltage, or may be charged by superimposing an AC voltage on the DC voltage.
Subsequently, the charged photosensitive surface of the photoconductor 1 is exposed by the exposure device 3 according to an image to be recorded, and an electrostatic latent image is formed on the photosensitive surface. Then, the developing device 4 develops the electrostatic latent image formed on the photosensitive surface of the photosensitive member 1.

The developing device 4 thins the toner T supplied by the supply roller 43 by the regulating member (developing blade) 45 and has a predetermined polarity (here, the same polarity as the charging potential of the photoconductor 1 and a negative polarity). ), And is transported while being carried on the developing roller 44, and is brought into contact with the surface of the photoconductor 1.
When the charged toner T carried by 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. Then, 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 photoconductor 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 toner image through the fixing device 7 and thermally fixing the toner image onto the recording paper P.
Note that the image forming apparatus may be configured to be able to perform, for example, a charge removing step in addition to the above-described configuration. The charge removing step is a step of removing the charge of the electrophotographic photosensitive member by exposing the electrophotographic photosensitive member, and a fluorescent lamp, an LED, or the like is used as the charge removing device. In addition, the light used in the charge removing step is often light having an exposure energy three times or more the intensity of the exposure light.

Further, the image forming apparatus may be further modified and configured, for example, a configuration capable of performing steps such as a pre-exposure step and an auxiliary charging step, a configuration performing offset printing, and a plurality of types. A full-color tandem system using toner may be used.
The electrophotographic photosensitive member 1 is combined with one or more of the charging device 2, the exposing device 3, the developing device 4, the transfer device 5, the cleaning device 6, and the fixing device 7 to form an integrated cartridge ( Hereinafter, the cartridge is appropriately referred to as an “electrophotographic photoreceptor cartridge”, and the electrophotographic photoreceptor cartridge may be configured to be detachable from a main body of an electrophotographic apparatus such as a copying machine or a laser beam printer. In this case, for example, when the electrophotographic photosensitive member 1 and other members are deteriorated, the electrophotographic photosensitive member cartridge is removed from the image forming apparatus main body, and another new electrophotographic photosensitive member cartridge is mounted on the image forming apparatus main body. This facilitates maintenance and management of the image forming apparatus.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto unless it exceeds the gist thereof. In addition, “parts” used in the examples indicates “parts by weight” unless otherwise specified.
<Production method of dispersion liquid S1>
A slurry obtained by mixing a rutile type titanium oxide having an average primary particle diameter of 40 nm (manufactured by Ishihara Sangyo Co., Ltd., product name: TTO55N) and 3% by weight of methyldimethoxysilane with respect to the titanium oxide in a ball mill is dried. Further, the hydrophobized titanium oxide obtained by washing with methanol and then drying was subjected to ball mill dispersion in a mixed solvent of methanol / 1-propanol to obtain a dispersion slurry of the hydrophobized titanium oxide.

  The dispersion slurry obtained here, methanol, 1-propanol, toluene, and nylon pellets represented by the following structural formula are stirred and mixed while heating to dissolve the nylon pellets, and then subjected to ultrasonic dispersion treatment. Finally, a dispersion of hydrophobically treated titanium oxide / nylon = 4/1 was prepared, and this was designated as dispersion S1.

<Method for preparing dispersion liquid S2>
The hydrophobized titanium oxide obtained in the same manner as in the preparation of the dispersion S1 was subjected to ball mill dispersion in a mixed solvent of methanol / 1-propanol to obtain a dispersed slurry of the hydrophobized titanium oxide. Similarly, an anatase type titanium oxide (product name: EC-100, manufactured by Titanium Industry Co., Ltd.) having an average particle diameter of 0.3 to 0.4 μm, which has been made conductive by conductive antimony-doped tin oxide. A dispersion slurry was prepared.

The obtained two dispersion slurries were mixed, and further, methanol, 1-propanol, toluene, and the same nylon pellets used during the preparation of the dispersion S1 were stirred and mixed while heating to dissolve the nylon pellets, Thereafter, a dispersion liquid of hydrophobically treated titanium oxide / EC-100 / nylon = 99/1/25 was finally prepared by performing an ultrasonic dispersion treatment, and this was designated as a dispersion liquid S2.
<Production method of coating liquid S3>
A dispersion liquid was prepared in the same manner as the coating liquid S2 except that the ratio of the hydrophobized titanium oxide / EC-100 / nylon was changed to the hydrophobized titanium oxide / EC-100 / nylon = 95/5/25. It was set to S3.
<Production method of coating liquid S4>
A dispersion liquid similar to the coating liquid S2 was prepared except that the ratio of the hydrophobized titanium oxide / EC-100 / nylon was changed to hydrophobic titanium oxide / EC-100 / nylon = 90/10/25. It was set to S4.
<Production method of coating liquid S5>
A dispersion liquid was prepared in the same manner as the coating liquid S2 except that the ratio of the hydrophobized titanium oxide / EC-100 / nylon was changed to the hydrophobized titanium oxide / EC-100 / nylon = 85/15 / 33.3. This was Dispersion S5.
<Production method of coating liquid S6>
A dispersion liquid similar to the coating liquid S2 was prepared except that the ratio of the hydrophobicized titanium oxide / EC-100 / nylon was changed to 75/25/50 of the hydrophobicized titanium oxide / EC-100 / nylon. S6.
<Example 1>
The dispersion liquid S2 was applied by dip coating to an aluminum cylinder having an outer diameter of 30 mm, a length of 250 mm, and a wall thickness of 1.0 mm, and an undercoat layer was provided so that the dry film thickness was 6 μm.
Next, the black angles (2θ ± 0.2 °) of the X-ray diffraction spectrum with respect to the CuKα characteristic X-ray show main peaks at 9.3 °, 13.2 °, 26.2 °, and 27.1 °. To 10 parts of A-type oxytitanium phthalocyanine and 5 parts of polyvinyl butyral (trade name # 6000-C, manufactured by Denki Kagaku Kogyo Co., Ltd.), 500 parts of 1,2-dimethoxyethane were added, and the mixture was pulverized and dispersed by a sand grinding mill. Was done. An aluminum cylinder provided with an undercoat layer was dip-coated on this dispersion, and a charge generation layer was provided such that the dry film thickness was 0.3 g / m ² (about 0.3 μm).

  Next, 100 parts of a polycarbonate resin having the following structure (monomer molar ratio, m: n = 7: 3)

50 parts of a hydrazone compound represented by the following structural formula

14 parts of a hydrazone compound represented by the following structural formula

2 parts of a cyano compound represented by the following structural formula

Was dissolved in a mixed solvent of 1,4 dioxane and tetrahydrofuran to form a charge transfer layer by immersion coating so that the film thickness after drying was 17.5 μm. The drum thus obtained is referred to as a photoconductor A1.
<Example 2>
A photoconductor was prepared in the same manner as in Example 1 except that the aluminum cylinder used in Example 1 was provided with a subbing layer by dip coating using a dispersion liquid S3 so that the dry film thickness was 6 μm. Obtained. The drum thus obtained is referred to as a photoconductor A2.
<Example 3>
A photoreceptor was prepared in the same manner as in Example 1 except that the aluminum cylinder used in Example 1 was provided with an undercoat layer by dip coating using a dispersion liquid S4 so as to have a dry film thickness of 6 μm. Obtained. The drum thus obtained is referred to as a photoconductor A3.
<Example 4>
A photoconductor was prepared in the same manner as in Example 1, except that the aluminum cylinder used in Example 1 was provided with an undercoat layer by dip coating using the dispersion liquid S5 so as to have a dry film thickness of 6 μm. Obtained. The drum thus obtained is referred to as a photoconductor A4.
<Comparative Example 1>
A photoconductor was prepared in the same manner as in Example 1 except that the aluminum cylinder used in Example 1 was provided with an undercoat layer by dip coating using the dispersion liquid S1 so as to have a dry film thickness of 6 μm. Obtained. The drum thus obtained is referred to as Comparative Photoconductor B1.
<Comparative Example 2>
A photoreceptor was prepared in the same manner as in Example 1 except that the aluminum cylinder used in Example 1 was provided with an undercoat layer by dip coating using the dispersion liquid S6 so as to have a dry film thickness of 6 μm. Obtained. The drum thus obtained is referred to as Comparative Photoconductor B2.

The volume resistivity of the undercoat layer is such that the undercoat layer coating liquids S1 to S6 are each coated with a wire bar on an aluminum deposition layer deposited on a polyester film so that the thickness after drying is 6 μm, The measurement was performed using the material for measuring volume resistivity obtained by drying. These samples were measured using a high resistivity meter (trade name, High Leicester-UP MCP-HT450, manufactured by Mitsubishi Chemical Corporation). The value calculated from the resistance value after one minute was measured, and the volume resistivity value was measured. Obtained. Table 1 shows the results.

実施例１〜４の感光体に用いた下引き層の体積抵抗率は、１×１０¹⁰〜１×１０¹³Ωｃｍの範囲であり、導電化処理された金属化合物粒子を含まない比較例１では体積抵抗率が１×１０¹³Ωｃｍを超え、導電化処理された金属化合物粒子を２５重量％含む比較例２では、体積抵抗率が１×１０¹⁰Ωｃｍ以下であった。
＜評価＞
次にこれらの電子写真感光体を感光体特性測定機に装着して、気温５℃、相対湿度１０％（以下、これをＬＬ環境ということがある）、気温２５℃、相対湿度５０％（以下、これをＮＮ環境ということがある）、気温３５℃、相対湿度８５％（以下、これをＨＨ環境ということがある）の各環境下で、表面電位が−６００Ｖになるように感光体を帯電させた後、７８０ｎｍの光を照射した時の表面電位が１／２になるのに要する露光量（以下、半減露光量またはＥ１／２ということがある）、表面電位を−６００Ｖになるように感光体を帯電させ５秒間放置したときの、帯電時と５秒放置後の電位の比（以下、ＤＤＲということがある）、６６０ｎｍのＬＥＤ光を照射した後の残留電位（以下、Ｖｒということがある）を測定した。結果を表２に示す。

The volume resistivity of the undercoat layer used for the photoreceptors of Examples 1 to 4 was in the range of 1 × 10 ¹⁰ to 1 × 10 ¹³ Ωcm, and in Comparative Example 1 which did not contain the metal compound particles subjected to the conductivity treatment. In Comparative Example 2 in which the volume resistivity exceeded 1 × 10 ¹³ Ωcm and the metal compound particles subjected to the conductivity treatment were 25% by weight, the volume resistivity was 1 × 10 ¹⁰ Ωcm or less.
<Evaluation>
Next, these electrophotographic photoreceptors are mounted on a photoreceptor characteristic measuring device, and the temperature is 5 ° C., the relative humidity is 10% (hereinafter, this may be referred to as LL environment), the temperature is 25 ° C., and the relative humidity is 50% (hereinafter, referred to as LL environment). The photoconductor is charged so as to have a surface potential of −600 V under each environment of 35 ° C. and 85% relative humidity (hereinafter sometimes referred to as an HH environment). After that, the exposure amount required to reduce the surface potential when irradiating light of 780 nm (hereinafter, sometimes referred to as half-exposure amount or E1 / 2) and the surface potential to -600 V are set. When the photosensitive member is charged and left for 5 seconds, the ratio of the potential at the time of charging and after 5 seconds (hereinafter, may be referred to as DDR), and the residual potential after irradiating 660 nm LED light (hereinafter, referred to as Vr) Was measured). Table 2 shows the results.

感光体Ａ１，Ａ２，Ａ３，Ａ４は、ＬＬ，ＮＮ，ＨＨの各環境下において、良好な電気特性を示すが、比較感光体Ｂ１は、特にＬＬ環境下において、６６０ｎｍのＬＥＤ光照射後の残留電位が大きくなり良好でない。また、比較感光体B2は、表面電位−６００Ｖまで帯電せず、電気特性を測定することができなかった。

The photoconductors A1, A2, A3, and A4 show good electrical characteristics in each of the LL, NN, and HH environments, but the comparative photoconductor B1 has a residual after irradiation of 660 nm LED light, particularly in the LL environment. Potential increases and is not good. Further, the comparative photoconductor B2 was not charged to a surface potential of −600 V, and the electrical characteristics could not be measured.

Next, these photoconductors A1 to A4 and comparative photoconductor B1 were mounted on a commercially available laser printer (LP-1700 manufactured by Seiko Epson Corporation), and 16,000 A4 paper sheets were printed in a 5% character pattern under an HH environment. Thereafter (2,000 sheets were printed a day), the exposure light (1.5 μJ / cm ² ) was irradiated with exposure light, and the potential was measured. Table 3 shows the results. A1, A2, A3
, A4, and B1 were good with little increase in potential compared to the initial stage.

＜比較例３＞
実施例１で用いたアルミニウム製シリンダーに、分散液Ｓ２を用いて、浸漬塗布により、その乾燥膜厚が３μｍとなるように下引き層を設けた以外は、実施例１と同様にして感
光体を得た。このようにして得たドラムを比較感光体Ｂ３とする。

<Comparative Example 3>
A photoconductor was prepared in the same manner as in Example 1 except that the undercoat layer was provided on the aluminum cylinder used in Example 1 by dip coating using the dispersion liquid S2 so as to have a dry film thickness of 3 μm. Got. The drum thus obtained is referred to as Comparative Photoconductor B3.

  The photoreceptor A1 and the comparative photoreceptor B3 were respectively mounted on a commercially available laser printer (LP1900, manufactured by Seiko Epson Corporation), which was characterized by brush charging to which DC and AC were applied. Was output on 20,000 sheets, and the dielectric breakdown was evaluated. In the case of the photoreceptor A1 having an undercoat layer thickness of 6 μm, no dielectric breakdown occurred even after printing for 20,000 sheets. The image shown appears. Table 4 shows the results.

FIG. 2 is a conceptual diagram illustrating an embodiment of an image forming apparatus using the electrophotographic photosensitive member of the present invention.

Explanation of reference numerals

Reference Signs List 1 photoconductor 2 charging device (charging roller)
Reference Signs List 3 exposure device 4 developing device 5 transfer device 6 cleaning device 7 fixing device 41 developing tank 42 agitator 43 supply roller 44 developing roller 45 regulating member 71 upper fixing member (fixing roller)
72 Lower fixing member (fixing roller)
73 Heating device T Toner P Recording paper

Claims (11)

An electrophotographic photoreceptor having a photosensitive layer and an undercoat layer containing metal compound particles and a binder resin on a conductive substrate, wherein the metal compound particles include metal compound particles subjected to a conductivity treatment. Electrophotographic photoreceptor. 2. The electrophotographic photoreceptor according to claim 1, wherein the undercoat layer has a volume resistivity of 1 × 10 ¹⁰ to 1 × 10 ¹³ Ωcm. The conductive compound-containing metal compound particles contained in the undercoat layer are present in an amount of 0.1 to 20% by weight based on all metal compound particles contained in the undercoat layer. The electrophotographic photosensitive member according to claim 2. The electrophotographic photosensitive material according to any one of claims 1 to 3, wherein the undercoat layer contains, in addition to the metal compound particles subjected to the conductivity treatment, metal oxide particles not subjected to the conductivity treatment. body. 5. The electrophotographic photoreceptor according to claim 4, wherein the metal oxide particles that have not been made conductive include a titanium atom as a constituent. The electrophotographic photosensitive member according to claim 4, wherein the average primary particle diameter of the metal oxide particles that have not been made conductive is 100 nm or less. The electrophotographic photosensitive member according to claim 1, wherein the undercoat layer has a thickness of 3 μm or more. The electrophotographic photoreceptor according to any one of claims 1 to 7, wherein the undercoat layer contains a polyamide resin as a binder resin. The electrophotographic photoreceptor according to any one of claims 1 to 8, wherein the charge generation substance contained in the photosensitive layer is a phthalocyanine pigment. An image forming apparatus using the electrophotographic photosensitive member according to claim 1. An image forming method using the image forming apparatus according to claim 10.

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