JP2002156772A - Electrophotographic photoreceptor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor of superior adhesiveness between an electrically conductive substrate and an undercoat layer and having proper electrical characteristics, such as electrification capability, light exposure reduced by half and residual potential. SOLUTION: In the electrophotographic photoreceptor, having at least an undercoat layer and a photosensitive layer on an electrically conductive substrate, the undercoat layer contains a polyurethane resin, obtained through reaction of a polyhydroxy compound containing a polycaprolactone polyol with a polyisocyanate compound.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electrophotographic photosensitive member having an undercoat layer. More specifically, the present invention relates to an electrophotographic photoreceptor having excellent adhesion to a conductive support and improved electrical characteristics.

[0002]

2. Description of the Related Art In recent years, electrophotographic technology has been widely used and used not only in the field of copying but also in the field of various printers because of its immediacy and high-quality images. The photoconductor, which is the core of electrophotographic technology, can be selected from conventional photoconductors such as selenium, arsenic-selenium alloy, cadmium sulfide, and zinc oxide as photoconductive materials. Organic photoconductors (OPCs) have become the mainstream of photoconductors in view of their properties, ease of manufacture (can be manufactured by coating), and the ability to select non-polluting materials in terms of safety. Various configurations of the OPC have been developed, such as a single layer type in which a charge generating material and a charge transporting material are dispersed in a binder, a charge generating layer, and a stacked type in which the function is separated from the charge transporting layer. In general, a stack type in which a charge generation layer and a charge transport layer are stacked on a substrate in this order.

Further, in recent years, it has become common to form an undercoat layer on a substrate and then form a photosensitive layer in order to improve electrical characteristics, image characteristics, and mechanical characteristics. As the binder resin for the undercoat layer, adhesion to the substrate, solvent resistance (the charge generation layer and the solvent for the charge transport),
Alcohol-soluble resins, particularly alcohol-soluble polyamide resins, are often studied and used as preferred resins in terms of coating properties and electrical barrier properties.

Further, in order to satisfy the required characteristics of the undercoat layer, the undercoat layer often contains inorganic particles such as metal oxide particles, particularly titanium oxide particles. Furthermore, in order to improve the performance as an undercoat layer,
Techniques for treating the metal oxide particles with an organic compound have been developed. In particular, a method of treating with an organic compound containing a metal atom, such as an organic silicon compound, is known (JP-A-8-328283, etc.).

[0005] Metal oxide particles treated with such organic compounds include polysiloxanes such as dimethylpolysiloxane and methylhydrogenpolysiloxane, stearic acid, and the like.
Metal oxide particles treated with a titanate-based treating agent, a silane compound, or the like were common. Titanium oxide particles are widely used as white pigments in paints and cosmetics as well as in the undercoat layer of electrophotographic photoreceptors. In addition, they are widely used as catalysts (photocatalysts), food additives, conductivity control agents, and the like. It is desired to make the particle surface hydrophobic for the purpose of improving the slipperiness or improving the environmental characteristics. As such titanium oxide particles subjected to hydrophobic treatment, those treated with lauric acid or stearic acid and those treated with a siloxane compound such as dimethylpolysiloxane or methylhydrogenpolysiloxane are generally known. Had been.

[0006]

By the way, many alcohol-soluble polyamide resins have been studied as a binder resin for the undercoat layer. This is due to the good electrical properties and image properties required for the undercoat layer of the electrophotographic photoreceptor, and the diversity of solvents used in the photosensitive layer from the viewpoint of alcohol solubility in productivity. On the other hand, there is a need for more improvements in recent high-performance printers and the like.

[0007] For example, environmental characteristics, particularly generation of minute black spots in a high-temperature and high-humidity environment, or generation of fog in a low-temperature and low-humidity environment. These are caused by the fact that the resistance value of the resin fluctuates depending on the environment, and it is considered that a resin that is less affected by the environment is required. Alternatively, in a printer using a contact charging system, the voltage (DC, AC) applied per unit area of the electrophotographic photosensitive member is larger than that of a non-contact type, and it is expected that dielectric breakdown is likely to occur. To cope with this, it may be necessary to increase the thickness of the undercoat layer or to select or develop a resin having a higher dielectric breakdown strength.

Further, in a contact charging type process, a device or a member of a printer repeatedly contacts a photoreceptor. In this process, a phenomenon that the photoreceptor and the substrate are separated from each other has been observed. As a result of investigating the cause, it was found that the resin was peeled between the undercoat layer and the substrate, and it was necessary to develop a resin having higher adhesion to the substrate. The gist of the present invention is an electrophotographic photoreceptor characterized in that a urethane elastomer is used as a binder for an undercoat layer in order to impart stronger adhesion and flexibility to the undercoat layer.

[0009]

Hereinafter, the present invention will be described in detail. The present inventors have conducted intensive studies to solve the above problems, and as a result, by using a polyurethane resin having a specific structure as a binder resin of the undercoat layer, the adhesiveness between the photosensitive layer and the base has been improved, and The inventors have found that the electric characteristics and image characteristics required for the characteristics of the photoreceptor are not deteriorated, and have reached the present invention.

That is, the gist of the present invention is to provide an electrophotographic photosensitive member having at least an undercoat layer and a photosensitive layer on a conductive support, wherein the undercoat layer comprises a polyhydroxy compound containing a polycaprolactone polyol and a polyhydroxy compound. An electrophotographic photoreceptor comprising a polyurethane resin obtained by a reaction with an isocyanate compound.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION <Conductive Support> As the conductive support on which a photosensitive layer is formed, any of those used in known electrophotographic photosensitive members can be used. Specifically, for example, aluminum, aluminum alloy, stainless steel,
Drums, sheets, belts made of metal materials such as copper and nickel, or laminates of these metal foils, deposits,
Alternatively, an insulating support such as a polyester film or paper provided with a conductive layer of aluminum, copper, palladium, tin oxide, indium oxide, or the like on the surface may be used. Furthermore, a conductive film such as a metal powder, carbon black, copper iodide, and a polymer electrolyte coated with an appropriate binder and subjected to conductive treatment, a plastic drum,
Paper, paper tube, and the like are included. In addition, a plastic sheet, belt, or drum containing a conductive material such as metal powder, carbon black, or carbon fiber and made conductive may be used. Further, plastic films and belts which have been subjected to conductive treatment with a conductive metal oxide such as tin oxide or indium oxide may be used.

[0012] Among them, an endless pipe made of a metal such as aluminum is a preferable support. <Undercoat layer> In the present invention, an undercoat layer is provided between the conductive support and the photosensitive layer. The undercoat layer used in the present invention contains a specific polyurethane resin and, if necessary, metal oxide particles treated with an organometallic compound represented by the following general formula (1).

The polyurethane resin used in the present invention has a weight average molecular weight of 5,000 to 200,000, preferably 10,000 to 150,
000. When the weight average molecular weight is 5,000 or less, the mechanical strength of the polyurethane resin is low, and the adhesive strength is poor. If the weight average molecular weight is 200,000 or more, the fluidity of the polyurethane resin and the solubility in a solvent deteriorate. The method for producing the polyurethane resin used in the present invention is appropriately selected from known production methods in consideration of the degree of polymerization of the target polyurethane resin, the type of raw materials used, and the like.

For example, if necessary, a solvent inert to an isocyanate group is usually used, and if necessary, an active hydrogen is converted to a temperature of 10 to 150 ° C., preferably 20 to 130 ° C. using a normal urethanization catalyst. Reacting a polyhydroxy compound having a compound stoichiometric excess with a polyisocyanate compound to produce a prepolymer having an isocyanate group at a terminal, and then reacting a diol, a diamine, a triol or the like as a chain extender to terminate the prepolymer. A method of obtaining a polyurethane resin containing a hydroxyl group, or a method of simultaneously reacting a polyhydroxy compound, a chain extender and a polyisocyanate compound at a charged amount at which the hydroxyl groups become stoichiometrically excessive to obtain a polyurethane resin having a terminal hydroxyl group. No. Also, a method of reacting a polyisocyanate compound with a polyhydroxy compound without using a chain extender to obtain a polyurethane resin having a terminal hydroxyl group, and further reacting a polyhydroxy compound with a polyisocyanate compound to obtain a terminal hydroxyl group, and further comprising A method of reacting an isocyanate compound to obtain a polyurethane resin having a terminal hydroxyl group can also be employed.

It is also possible to adopt a method in which bulk polymerization is carried out without using a solvent, followed by cooling and pulverization to obtain a powdery resin. In the present invention, the average molecular weight obtained by ring-opening polymerization of ε-caprolactone using bishydroxyethyl terephthalate as an initiator glycol as a polyhydroxy compound having two or more active hydrogens in the molecule is from 250 to 100.
A compound containing a polycaprolactone polyol of 00 is used.

As the bishydroxyethyl terephthalate, one containing not more than a pure monomer but not more than 20% by weight of an oligomer having a degree of polymerization of 2 to 4 as shown below can be used.

[0017]

Embedded image

N = 1 Monomer n = 2 to 4 Oligomer having a degree of polymerization of 2 to 4 Polycaprolactone polyol is ring-opened according to a method known per se in the presence of ε-caprolactone in the presence of a catalyst and bishydroxyethyl terephthalate as a glycol initiator. It is obtained by polymerizing.

In the present invention, it is necessary to include the above-mentioned polycaprolactone polyol as a polyhydroxy compound having two or more active hydrogens in the molecule, but other polyhydroxy compounds can be used in combination. As such other polyhydroxy compounds, those having a molecular weight of 50 to 10,000 are generally used, and known polyhydroxy compounds generally used for polyurethane resin production, for example, polyethers, polyesters,
Polythioethers, polybutadiene glycols, silicon-containing polyols, phosphorus-containing polyols and the like can be used.

The low molecular weight glycols include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol,
1,3-butanediol, 1,4-butanediol, pentamethylene glycol, hexamethylene glycol, neopentyl glycol, 2-ethyl-1,3-hexanediol, N-alkyldiethanolamine, bisphenol A and the like are used. . Further, a diol having a carboxyl group such as dimethylolpropionic acid or a low-molecular-weight polyol such as trimethylolpropane may be partially mixed and used.

Examples of the polyethers include polymerization products or copolymers of ethylene oxide, propylene oxide, tetrahydrofuran and the like. Polyethers obtained by condensation of the low-molecular glycols or mixed ethers, and products obtained by addition-polymerizing ethylene oxide and propylene oxide to these polyethers and the low-molecular glycol can also be used.

As the polythioethers, the use of thioglycol alone or a condensation product thereof with other glycols is particularly preferred. Examples of the polyesters include polyesters obtained by dehydration condensation reaction from low molecular weight glycols and dibasic acids and lactone polyols obtained by ring-opening polymerization of lactones such as ε-caprolactone in the presence of the low molecular weight glycols and the like. No.

It is also possible to use a mixture of polyols having a trifunctional or higher functionality as the polyhydroxy compound. In the present invention, the content of the polycaprolactone polyol is at least 10 wt% based on the total amount of the polyhydroxy compound having two or more active hydrogens in the molecule.
%, And when the proportion of the polycaprolactone polyol used is 10% by weight or less, the adhesiveness and hydrolysis resistance, which are features of the present invention, may not be sufficiently exhibited.

The polyisocyanate compound used for producing a polyurethane resin by reacting with a polyhydroxy compound in the present invention includes 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, and 4,4'-diphenyl. Methane diisocyanate, naphthalene-1,5-diisocyanate, tolidine diisocyanate, xylylene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, lysine ethyl ester diisocyanate, 4,4 'methylene bis (cyclohexyl isocyanate), ω, ω'-diisocyanate dimethylcyclohexane, etc. Organic diisocyanate compounds and adducts of these organic diisocyanate compounds with polyhydric alcohols can be used.

Examples of chain extenders used in the production of polyurethane resins include glycols such as ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, pentanediol, trimethylolpropane, and glycerin. And diamines such as ethylenediamine, propylenediamine, hydrazine, piperazine and isophoronediamine. It is also possible to use the above-mentioned polyhydroxy compounds as chain extenders. In the present invention, as a solvent for producing a polyurethane resin, usually, ketones such as methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, and the like, ethyl acetate, esters such as butyl acetate, and aromatics such as toluene and benzene, which are inert to isocyanate groups. A hydrocarbon solvent, tetrahydrofuran or the like is used.

As a catalyst for producing a polyurethane resin, a tin-based, iron-based, or tertiary amine-based catalyst which is a usual urethanization reaction catalyst is used. Examples of the tin catalyst include dibutyltin dilaurate, dioctyltin dilaurate, dibutyltin dioctoate, and stannas octoate. Examples of the iron-based catalyst include iron acetylacetonate and ferric chloride. Examples of the tertiary nitrogen-based catalyst include triethylamine and triethylenediamine.

The adhesive of the present invention can be used alone or mixed with a low molecular weight polyisocyanate compound as a crosslinking agent. At this time, pigments and colorants such as carbon black, titanium oxide and silica powder, ultraviolet absorbers, antioxidants and the like may be added according to the purpose. Also commonly used polyurethane resin to enhance the effect as an adhesive,
It is also possible to use a mixture of an acrylic resin, an epoxy resin, a rubber-based resin, a PVC-based resin, a cellulose-based resin, a polyolefin resin, a polyester resin, or the like. As the low molecular weight polyisocyanate compound, an adduct of an isocyanate compound containing two or more isocyanate groups (an adduct with a dihydric or trihydric polyhydric alcohol,
Adducts such as monomers, trimers and the like, adducts with water, etc.) can be used. Examples of such low molecular weight polyisocyanate compounds include Desmodur L and Desmodur N manufactured by Bayer, Coronate L and Coronate HL manufactured by Nippon Polyurethane Industry Co., Ltd., and Mitec manufactured by Mitsubishi Chemical Corporation. GP105A, Mytec NY218A (registered trademark of Mitsubishi Chemical Corporation) and the like. These low molecular weight polyisocyanate compounds are used in an amount of 3 to 50 based on the total amount of the binder.
(Weight)% used.

The metal oxide particles to be contained in the undercoat layer as required are treated with an organometallic compound represented by the following general formula (1).

[0029]

Embedded image

R in the general formula (1) is specifically a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, a sec-butyl group, a tert-group. Examples thereof include -butyl group and n-hexyl group, and among them, a hydrogen atom is particularly preferable. R1, R2
Is a linear or branched alkyl group having 1 to 6 carbon atoms, and from the viewpoint of reactivity with metal oxide particles during surface treatment, those having 1 to 4 carbon atoms are more preferable, and a methyl group,
Ethyl groups are particularly preferred. M is SiR3, TiR3 or Al, where R3 is an alkyl group or alkoxy group having 1 to 6 carbon atoms, or an alkoxyalkyl group or alkoxyalkoxy group having 2 to 6 carbon atoms in total. Specifically, alkyl groups such as methyl group, ethyl group, n-propyl group, i-propyl group, butyl group, heptyl group and hexyl group; alkoxy groups such as methoxy group, ethoxy group, propoxy group and butoxy group; Methyl group, methoxyethyl group,
Examples thereof include an alkoxyalkyl group such as an ethoxymethyl group and an ethoxyethyl group; and an alkoxyalkoxy group such as a methoxymethoxy group, a methoxyethoxy group, an ethoxymethoxy group, and an ethoxyethoxy group. Among these, a methyl group, an ethyl group, a methoxy group and an ethoxy group are particularly preferred.

Among the organometallic compounds represented by the above general formula (1), particularly preferred are the organosilicon compounds represented by the following general formula (2).

[0032]

Embedded image

(Wherein, R ^{4 and} R ⁵ each independently represent a methyl group or an ethyl group, and R ⁶ represents a methyl group, an ethyl group,
It represents one type of group selected from a methoxy group and an ethoxy group. The surface treatment of the metal oxide with the above-mentioned surface treating agent can be performed by either a dry method or a wet method.
In the case of the dry method, the base metal oxide is charged into a high-speed stirrer such as a Henschel mixer, a super mixer, etc., and the solution of the above surface treatment agent is dropped or sprayed onto the high-speed stirrer and uniformly adhered thereto while stirring at a high speed. After that, it may be added by spraying, stirred to make it uniform, and then dried. In the case of the wet method, the base titanium oxide and the surface treating agent are added to a solvent, and the mixture is subjected to a dispersion treatment using a bead mill such as a ball mill, a co-ball mill, a sand grind mill, and a pearl mill, and then the solvent may be evaporated. In both methods, it is preferable to perform baking at about 100 ° C. to about 200 ° C. during or after the treatment to further strengthen the bond between the metal oxide and the surface treating agent.

Among the metal oxides, titanium oxide particles are preferred for improving the properties of the undercoat layer, and metal oxide particles having an average primary particle diameter of 100 nm or less are preferred in terms of properties and dispersion stability of the coating solution. . Particularly preferred are titanium oxide particles having an average primary particle size of 100 nm or less. The titanium oxide particles may be either crystalline or amorphous. The most common crystalline titanium oxide is rutile, but may be anatase, brookite or the like.

The metal oxide particles treated with the above-mentioned organometallic compound may be treated with an inorganic substance such as alumina, silica, zirconia and the like in addition to the above-mentioned treating agent. The ratio between the metal oxide particles treated with the organometallic compound and the binder resin can be arbitrarily selected, but from the viewpoint of the characteristics and the stability of the coating solution, the weight ratio is 0.1 / 1 to 10/1.
Is more preferable, and more preferably, it is a range of 2/1 to 5/1.

Further, various surfactants may be added for the purpose of improving coating properties and dispersibility of dispersed particles. In addition, it may contain a leveling agent and an antioxidant. The undercoating coating solution can be prepared as follows. The metal oxide particles treated with the organic compound are subjected to a dispersion treatment using a ball mill, a co-ball mill, a sand mill, or the like, and then diluted to an appropriate concentration to prepare a slurry. A binder dissolving solution previously dissolved in a solvent is added to the slurry and mixed to prepare a subbing coating solution. Alternatively, binder pellets and powder are directly added to the slurry, mixed and stirred, and the binder is dissolved to prepare an undercoating coating solution. Conversely, it can also be produced by adding metal oxide particles treated with an organic compound to a binder solution and performing the above-mentioned dispersion treatment. In these manufacturing processes, various additives can be arbitrarily added. If necessary, a heat treatment, an ultrasonic treatment, or the like may be added.

The undercoat coating solution thus prepared is applied on a substrate and dried to form an undercoat layer. As a coating method at this time, any method such as spray coating, nozzle coating, blade coating, spin coating, and dip coating may be used, and among these, dip coating is most commonly used. The thickness of the undercoat layer can be appropriately set, but is usually 0.05 to 20 μm.
m, preferably in the range of 0.1 to 10 μm.

These undercoat layers may be used alone or in combination. <Photosensitive layer> (1) Laminated type photosensitive layer Charge generating layer In the case of a laminated type, a layer in which a charge transporting layer is laminated on a charge generating layer or a layer in which a charge generating layer is laminated on a charge transporting layer may be used.

First, the charge generation layer will be described. A charge generation layer is preferably formed on the barrier layer. The charge generation layer can also be formed by depositing a charge generation material, but the charge generation material and, if necessary, other organic photoconductive compounds, dyes, electron-withdrawing compounds, etc. are dissolved in a solvent together with a binder resin. Alternatively, it can be formed by applying a known coating method such as a wire bar, a doctor blade, a film applicator, immersion, spraying or the like, dispersing and applying the obtained coating liquid, and drying.

As the charge generating substance, inorganic photoconductive particles such as selenium, selenium-tellurium alloy, selenium-arsenic alloy, cadmium sulfide, amorphous silicon, metal-free phthalocyanine, metal-containing phthalocyanine, perinone pigment,
Organic photoconductive particles such as thioindigo, cycridone, perylene pigment, anthraquinone pigment, azo pigment, bisazo pigment, trisazo pigment, tetrakis azo pigment, and cyanine pigment. Further, various organic pigments and dyes such as polycyclic quinone, pyrylium salt, thiopyrylium salt, indigo, anthantrone and pyranthrone can be used. Among them, metals such as metal-free phthalocyanines, copper, indium chloride, gallium chloride, tin, oxytitanium, zinc, and vanadium, or oxides thereof, phthalocyanines with coordinated chlorides, azos such as monoazo, bisazo, trisazo, and polyazos Pigments and perylene pigments are preferred.

The charge generating substance may be used alone,
You may use it in the form which mixed plural. Examples of the binder resin include polyester, polyvinyl acetate, polycarbonate, polyvinyl acetoacetal, polyvinyl propional, polyvinyl butyral, phenoxy, epoxy, urethane, cellulose ester, and cellulose ether. Also, styrene, vinyl acetate,
Polymers and copolymers of vinyl compounds such as vinyl chloride, acrylates, methacrylates, vinyl alcohol and ethyl vinyl ether, polyamides, silicon resins and the like may be used. These binder resins are used alone or in a blend. The charge generation layer can be formed as a dispersion layer in which the charge generation material and other additives are bound to the binder resin.

In this case, the charge generating substance is used in an amount of usually from 20 to 2,000 parts by weight, preferably from 30 to 500 parts by weight, more preferably from 33 to 500 parts by weight, based on 100 parts by weight of the binder resin. The thickness of the charge generation layer is usually 0.05 to 5 μm, preferably 0.1 to 2 μm.
m, more preferably 0.15 to 0.8 μm. Further, the charge generation layer may contain various additives such as a leveling agent, an antioxidant, and a sensitizer for improving coating properties.

Charge Transport Layer The charge transport layer is formed by mixing a known polymer having excellent performance as a binder on the charge generation layer, dissolving it in a suitable solvent together with a charge transport material, It can be produced by applying a coating liquid obtained by adding a receptive compound or a plasticizer, a pigment or other additives. The thickness of the charge transfer layer is usually 5 to 50.
μm, preferably in the range of 10 to 35 μm.

Examples of the charge transport material in the charge transport layer include high molecular compounds such as polyvinyl carbazole, polyvinyl pyrene, and polyacenaphthylene, or various pyrazoline derivatives, oxazole derivatives, hydrazone derivatives, stilbene derivatives, arylamine derivatives, butadiene derivatives. And other low molecular weight compounds can be used. As the binder resin, 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 the like, and polycarbonate resin is most preferable. These resins may be partially crosslinked.

The ratio between the binder resin and the charge transport material is
It is used in an amount of 10 to 200 parts by weight, preferably 20 to 150 parts by weight, based on 100 parts by weight of the binder resin. Examples of electron accepting compounds that may be added to the charge transfer layer include cyano compounds such as tetracyanoquinodimethane, dicyanoquinomethane, aromatic esters having a dicyanoquinovinyl group, and 2,4,6-trinitro compounds. Nitro compounds such as fluorenone, condensed polycyclic aromatic compounds such as perylene, diphenoquinone derivatives, quinones, aldehydes,
Examples include ketones, esters, acid anhydrides, phthalides, substituted and unsubstituted metal complexes of salicylic acid, substituted and unsubstituted metal salts of salicylic acid, metal complexes of 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,
It is preferred to use substituted and unsubstituted metal salts of salicylic acid, metal complexes of aromatic carboxylic acids, and metal salts of aromatic carboxylic acids.

Further, it is known that organic pigments, resin particles, metal oxides and the like are added to the charge transport layer in order to improve mechanical strength. For the same reason as in the case of forming the undercoat layer, metal oxide particles treated with the organometallic compound represented by the general formula (1) are desirable. As a method for forming the charge transport layer,
A coating liquid obtained by dissolving or dispersing a substance to be contained in a layer in a solvent is formed by coating and drying by a known coating method such as a wire bar, a doctor blade, a film applicator, immersion, and spraying. Can be.

Further, the photosensitive layer of the electrophotographic photoreceptor of the present invention has a well-known plasticizer, antioxidant, ultraviolet absorber, and leveling for improving film formability, flexibility, coatability and mechanical strength. An agent may be contained. (2) Single-layer type photoconductor Next, the case where the photosensitive layer is a single-layer type will be described. When a single-layer photosensitive layer is provided by a casting method, a function-separation type layer composed of a charge generating substance and a charge transporting substance is often used. That is, the above-mentioned materials can be used as the charge generating substance and the charge transporting substance.

The single-layer photosensitive layer can be formed by dissolving or dispersing the charge generating substance, the charge transporting substance, and the binder resin in a suitable solvent, and applying and drying this. If necessary, a plasticizer, a leveling agent, an antioxidant, an electron transporting agent and the like can be added. As the binder resin, in addition to using the binder resin described above for the laminated charge transport layer as it is, a mixture of the binder resin described above for the laminated charge generation layer may be used.

The single-layer type photosensitive layer is obtained by dispersing a charge generating substance, a charge transporting substance and a binder resin in a ball mill, an attritor, a sand mill or the like using a solvent such as tetrahydrofuran, cyclohexanone, dioxane, dichloroethane or butanone. It can be formed by appropriately diluting and applying. The coating can be performed using a known coating method such as a wire bar, a doctor blade, a film applicator, and dipping or spraying. A photoreceptor obtained by adding a charge transporting substance to an amorphous complex formed from a pyrylium-based dye or bisphenol A-based polycarbonate can also be formed from a suitable solvent by a similar coating method. The thickness of the single-layer photoreceptor is suitably about 5 to 100 μm.

<Electrophotographic Photoreceptor> The electrophotographic photoreceptor of the present invention is provided with at least a photosensitive layer on a conductive support and, if necessary, a barrier layer and a photosensitive layer on the conductive support as described above. However, needless to say, an intermediate layer, a transparent insulating layer, and a surface protective layer may be further provided as necessary.

For example, a conventionally known overcoat layer mainly composed of, for example, a thermoplastic or thermosetting polymer may be used as the outermost surface layer. The electrophotographic photoreceptor thus obtained is a photoreceptor that maintains excellent printing durability over a long period of time, and is suitable for electrophotographic fields such as copying machines, printers, fax machines, and plate making machines.

<Electrophotographic Apparatus and Electrophotographic Method> An electrophotographic apparatus such as a copying machine or a printer using the electrophotographic photosensitive member of the present invention includes at least each of charging, exposure, development, and transfer processes. Any of the commonly used methods may be used. As the charging method (charging device), for example, any of corotron or scorotron charging using corona discharge, contact charging using a conductive roller, a brush, a film, or the like may be used.
Among them, in the charging method using corona discharge, scorotron charging is often used in order to keep the dark area potential constant. When contact charging is used, only a DC voltage may be applied, or a DC voltage superimposed on an AC voltage may be applied.

In the present invention, the exposure is usually performed at a wavelength of 5
Laser light such as He-Ne, a halogen lamp, a fluorescent lamp, an exposure device that emits LED light, etc. are used.
It is preferable to use D light, especially 530 to 850 nm
Laser light or LED light is preferred. In particular,
Around 532 nm, around 635 nm, around 650 nm, 7
Laser light around 80nm, around 830nm, 740n
LED light near m.

As a developing method, there is used a general method in which a magnetic or non-magnetic one-component developer, a two-component developer or the like is brought into contact or non-contact with the development. As a transfer method, any of a method using corona discharge, a method using a transfer roller or a transfer belt, and the like may be used. The transfer may be performed directly on paper or an OHP film, or may be once transferred onto an intermediate transfer body (belt or drum shape) and then transferred onto paper or an OHP film.

Usually, after the transfer, a fixing process of fixing the developer on paper or the like is used, and as a fixing means, generally used heat fixing, pressure fixing and the like can be used. In addition to these processes, a process such as cleaning and static elimination that is generally used may be provided.

[0056]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist thereof. Note that “parts” used in the examples indicates “parts by weight” unless otherwise specified. <Preparation of Dispersion (P1)> The dimethyldimethoxysilane surface-treated titanium oxide was first manufactured as Titanium Oxide by Ishihara Sangyo Co., Ltd., product name TTO-55N (crystal rutile primary particle size: 0.03 to 0.05 μm) The surface was uniformly coated with 3% by weight of methyl hydrogen polysiloxane.

Next, the obtained titanium oxide treated with dimethyldimethoxysilane and cyclohexanone were mixed in a ball mill for 16 hours.
Time dispersed. The titanium oxide dispersion obtained here was added to a cyclohexanone solution (solid content: 25% by weight) of a polyurethane resin obtained by the following method. [Production of Polyurethane Resin] A 2 L four-neck separable flask was prepared by ring-opening polymerization of ε-caprolactone with bishydroxyethyl terephthalate.
0 of 228 g of polyol and 8.1 of 1,4-butanediol 8.1
g, trimethylolpropane 4.0 g, cyclohexanone 1012.8 g, dibutyltin dioctoate 0.0
34g was charged and uniformly mixed and dissolved. Then, 97.5g of 4,4'-diphenylmethane diisocyanate was melted and added dropwise.
The reaction was carried out at 0 ° C. for 12 hours to obtain a polyurethane resin A. This had a solid content of 25% and a weight average molecular weight of 30,000.

A dispersion having a solid content concentration of 16% by weight was prepared from the titanium oxide and polyurethane resin obtained by the above method at a titanium oxide / polyurethane resin ratio of 3/1 (weight ratio), and diphenylmethane was used as a curing agent. A dispersion was prepared by adding 10% by weight of diisocyanate to the polyurethane resin, and this was designated as dispersion (P1). <Preparation of Dispersion (P2)> Dispersion (P1) except that diphenylmethane diisocyanate was added as a curing agent to the dispersion (P1) in an amount of 20% by weight based on the polyurethane resin.
And a dispersion (P2).

<Preparation of Dispersion (P3)> Dispersion (P1)
A dispersion liquid (P3) was prepared in exactly the same manner as the dispersion liquid (P1) except that 0.02% by weight of dibutyltin dilaurate was added to the polyurethane resin as a curing catalyst. <Preparation of dispersion liquid (Q1)> 6/6, 6/12 (composition ratio 3
0/36/34% by weight) Copolymer nylon 10% mixed alcohol (methanol / 1-propanol = 70/3)
0) A mixed alcohol dispersion (solid content: 10 wt%) of aluminum oxide-C (primary particle size average diameter: 20 nm) previously dispersed by ultrasonic wave into a solution is mixed with the solution, and further subjected to ultrasonic dispersion treatment to obtain a solid A dispersion of 10% by weight was prepared. This dispersion was designated as (Q1).

Example 1 A 75 μm-thick polyester film on which aluminum was vapor-deposited was used as a conductive support, on which a dispersion (P1) was applied using a wire bar, and dried at room temperature for 20 minutes after application. After drying, drying was performed at 150 ° C. for 20 minutes, and an undercoat layer was provided so that the film thickness after drying was 0.5 μm.

Next, in the powder X-ray diffraction spectrum by CuKα ray, the flag angle (2θ ± 0.2 °) 27.3.
In addition to 10 parts of Y-type oxytitanium phthalocyanine showing a main diffraction peak at 5 ° and 5 parts of polyvinyl butyral (trade name # 6000-C, manufactured by Denki Kagaku Kogyo Co., Ltd.), 500 parts of 1,2-dimethoxyethane was added, and a sand grinding mill And crushed and dispersed. This dispersion is applied to a conductive support provided with an undercoat layer with a wire bar, and a charge generation layer is provided so that the dry film thickness becomes 0.4 g / m ² (about 0.4 μm). Was.

Next, 56 parts by weight of the following hydrazone compound was added to the conductive support.

[0063]

Embedded image

14 parts by weight of the following hydrazone compound

[0065]

Embedded image

2 parts by weight of the following cyan compound

[0067]

Embedded image

8 parts by weight of the following phenol compound

[0069]

Embedded image

Further, the following 2 manufactured by the manufacturing method described in the examples of JP-A-3-221962.
A solution prepared by dissolving 100 parts of a polycarbonate resin having two repeating structural units (monomer molar ratio of 1: 1) in a mixed solvent of 1,4 dioxane and tetrahydrofuran is applied to the charge generation layer with an applicator, and then applied at room temperature to 30 parts.
And dried at 125 ° C. for 20 minutes.
m, the charge transfer layer was provided. This photoreceptor is A1
And

[0071]

Embedded image

Example 2 A photoconductor was provided in the same manner as in Example 1 except that the conductive support used in Example 1 was provided with an undercoat layer using the dispersion (P2). This photoconductor is referred to as A2. Example 3 A photoconductor was provided in the same manner as in Example 1 except that the conductive support used in Example 1 was provided with an undercoat layer using the dispersion (P3). This photoconductor is referred to as A3.

Comparative Example 1 The dispersion (P7) was applied to the conductive support used in Example 1 with a wire bar, dried at room temperature for 10 minutes, and provided with an undercoat layer having a dry film thickness of 0.5 μm. A photosensitive member was provided in the same manner as in Example 1 except for the above. This photosensitive member is designated as B1. [Evaluation] Next, these electrophotographic photoreceptors were measured for photoreceptor characteristics.
Attached to [Model EPA8100 manufactured by Kawaguchi Electric Co., Ltd.]
After being charged so that the current flowing into the aluminum surface becomes 25 μA, exposure and static elimination are performed, and the chargeability (Vo) at that time, the rate of decrease in potential (dark decay DD) after leaving for 2 seconds from the start of charging, and halving Exposure (E1 / 2 Reference potential: -45
0 V) and the residual potential (Vr) were measured. Table-
Shown in 1.

[0074]

[Table 1]

A1, A2 and A3 in the examples are comparative examples B1
In contrast, the charging ability (V0) and half-exposure amount are good. Also, the residual potential showed the same characteristics. Next, the photoreceptor A2 and the photoreceptor B1 of the comparative example (each having three photoreceptors) were cut at intervals of 1 mm to form 100 grids, and a cellophane tape was pressed thereon, and immediately The tape was peeled off, and the number of grids peeled off was checked. Table 2 shows the results.

[0076]

[Table 2]

From the above results, the photosensitive member A2 was compared with the photosensitive member A2 of Comparative Example.
It can be seen that the adhesiveness to No. 1 was very excellent with the conductive support.

[0078]

According to the electrophotographic photoreceptor of the present invention, since the binder resin having a specific structure is used as the binder resin for the undercoat layer, the electroconductive photoreceptor has excellent adhesiveness between the conductive support and the undercoat layer, and has good chargeability. The electrical properties such as the property, half-exposure amount, and residual potential are improved.

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Hiroaki Takamura 1060 Narita, Odawara-shi, Kanagawa F-term in Odawara Plant of Mitsubishi Chemical Corporation's Information & Electronics Company (reference) 2H068 AA43 AA44 BA57 BA58 BB29 BB52 CA29 EA01 EA12 4J002 CK031 DE136 FB076 FB096 GP03

Claims (9)

[Claims] 1. An electrophotographic photoreceptor having at least an undercoat layer and a photosensitive layer on a conductive support, wherein the undercoat layer is formed by reacting a polyhydroxy compound containing a polycaprolactone polyol with a polyisocyanate compound. An electrophotographic photosensitive member comprising the obtained polyurethane resin. 2. The electrophotographic photoreceptor according to claim 1, wherein the polycaprolactone polyol is obtained by polymerizing ε-caprolactone using bishydroxyethyl terephthalate as an initiator. 3. The polycaprolactone polyol has a number average molecular weight of 250 to 10,000.
2. The electrophotographic photoreceptor of claim 1. 4. A polycaprolactone polyol comprising at least 10% by weight based on the total amount of the polyhydroxy compound.
The electrophotographic photoreceptor according to any one of claims 1 to 3, which contains. 5. The electrophotographic photoreceptor according to claim 1, wherein the undercoat layer contains metal oxide particles treated with an organometallic compound represented by the following general formula (1). Embedded image (Wherein, M represents SiR ³ , TiR ³ , Al, R represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and R ¹ and R ² each independently represent 1 to 6 carbon atoms. Represents an alkyl group, and R ³ represents an alkyl group having 1 to 6 carbon atoms which may be substituted with an alkoxy group or an alkoxy group.) 6. The electrophotographic photoreceptor according to claim 5, wherein the metal oxide particles are titanium oxide. 7. An organic metal compound represented by the following general formula (2):
7. The organic silicon compound represented by claim 5 or 6.
Electrophotographic photoreceptor. Embedded image(Where R^FourAnd R^Five Is independently a methyl group
Or an ethyl group. R ⁶ Is methyl, ethyl, meth
One group selected from the group consisting of an xy group and an ethoxy group
Is shown. ) 8. The metal oxide particles have an average primary particle diameter of:
The electrophotographic photosensitive member according to any one of claims 5 to 7, wherein the thickness is 100 nm or less (as measured from a TEM photograph). 9. The method for producing an electrophotographic photosensitive member according to claim 1, wherein the undercoat layer is formed by coating.