JP2005321617A - Electrophotographic photoreceptor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor excellent in wear resistance in repetitive use, having electrophotographic properties which are equivalent to or higher than those obtained at the time of using a conventional halogen-containing solvent, and also excellent in potential characteristics, durability, image properties and resolution under various service conditions over a prolonged period of time from the initial stage of image formation. <P>SOLUTION: In the electrophotographic photoreceptor having a photosensitive layer on a conductive support, a surface layer of the electrophotographic photoreceptor is formed by applying and drying a solution comprising a binder resin, a diorganopolysiloxane having a specific repeating structural unit and a weight average molecular weight of 1,000-1,000,000 and an aromatic hydrocarbon solvent having a boiling point of ≥80°C. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electrophotographic photoreceptor, and more particularly to an electrophotographic photoreceptor containing a specific silicone resin in a surface layer.

  One typical example of the image holding member is an electrophotographic photosensitive member. In recent years, electrophotographic technology has been widely used and applied not only in the field of copying machines but also in the field of various printers because of its immediacy and high quality images. The core photoconductors include inorganic materials such as selenium, cadmium sulfide, and zinc oxide, but in recent years they are organic in terms of pollution-free, high productivity, ease of material design, and future prospects. System materials are being developed extensively.

  These electrophotographic photoreceptors are required to have electrical characteristics, mechanical characteristics, and optical characteristics according to the applied electrophotographic process. In particular, for electrophotographic photoreceptors that are used repeatedly, electrical and mechanical external forces such as charging, image exposure, toner development, transfer and cleaning are repeatedly applied directly or indirectly, so durability is required. In particular, with the miniaturization of the main body, higher image quality, and colorization, the toner image developed over the life of the photoconductor from the beginning of use of the photoconductor is efficiently transferred to a transfer medium (paper, intermediate transfer body). As a means for improving the transfer efficiency of this photoreceptor, it is known to improve the releasability of the surface of the electrophotographic photoreceptor by incorporating a silicone resin in the surface layer of the electrophotographic photoreceptor. (For example, refer to Patent Document 1).

  However, when a silicone resin is contained in the surface layer of the electrophotographic photosensitive member, the water repellency of the surface of the electrophotographic photosensitive member is improved to some extent, but it is not yet sufficient as the releasability required at the time of transfer. . In addition, since the silicone resin easily migrates to the surface of the layer, even if the effect is obtained in the initial stage, if the surface of the electrophotographic photoreceptor is worn due to durable use, the effective components are lost, and the effect is maintained over a long period of time. Cannot be maintained. Furthermore, it is also known that the residual potential is increased as an adverse effect due to the addition of the silicone resin (see, for example, Patent Document 2).

  In that respect, when the fluorine atom-containing resin particles are dispersed in the surface layer of the electrophotographic photosensitive member, an improvement in the releasability of the surface of the electrophotographic photosensitive member can be expected compared to the case of using a silicone resin. Fluorine atom-containing resin particles include tetrafluoroethylene resin, trifluoroethylene chloride resin, tetrafluoroethylene hexafluoroethylenepropylene resin, vinyl fluoride resin, vinylidene fluoride resin, difluorodiethylene chloride resin, And particles, such as these copolymer resins, are mentioned.

However, since the fluorine atom-containing resin particles in the surface layer of the electrophotographic photosensitive member scatter the exposure light, it is difficult to obtain a sharp electrostatic latent image, and there may be restrictions in terms of image quality (for example, (See Patent Document 3).
JP-A-10-171135 Japanese Unexamined Patent Publication No. 2000-267315 Japanese Unexamined Patent Publication No. 2000-81715

  An object of the present invention is to provide an electrophotographic photosensitive member that has excellent electrophotographic characteristics, can maintain potential characteristics and high transfer efficiency over a long period of time from the initial stage of image formation under a wide range of usage conditions, and can provide a good image. It is to be.

In the present invention, the surface layer of the electrophotographic photosensitive member has at least a binder resin, a repeating structural unit α represented by the following formula (1) and a repeating structural unit β represented by the following formula (2), and a weight: An electrophotographic photosensitive film formed by applying and drying a solution containing a diorganopolysiloxane having an average molecular weight of 1,000 to 1,000,000 and an aromatic hydrocarbon solvent having a boiling point of 80 ° C. or higher. Is the body.

  According to the present invention, it is possible to provide an electrophotographic photosensitive member that is excellent in durability and suppresses fluctuations in bright part potential due to repeated use. In particular, the effect is remarkable under high temperature and high humidity, and a photoconductor suitable for the next generation electrophotographic apparatus requiring high speed, high image quality and high durability can be provided.

  As described above, inclusion of fluorine atom-containing resin particles in the surface layer of the electrophotographic photosensitive member can be expected to improve the releasability of the surface of the electrophotographic photosensitive member, while the fluorine atom-containing resin particles scatter exposure light. If the exposure light is scattered, it becomes difficult to obtain a sharp electrostatic latent image. Therefore, the surface layer of the electrophotographic photosensitive member of the present invention does not contain fluorine atom-containing resin particles.

  Therefore, the surface layer of the electrophotographic photoreceptor of the present invention has a repeating structural unit α represented by the following formula (1) and a repeating structural unit β represented by the following formula (2) instead of the fluorine atom-containing resin particles. And a diorganopolysiloxane having a weight average molecular weight of 1,000 to 1,000,000. As a result, the releasability of the surface of the electrophotographic photosensitive member can be improved without causing exposure light scattering, and the transfer efficiency can be sufficiently increased.

In the above formulas (1) and (2), R ¹¹ and R ¹² each independently represent a substituted or unsubstituted monovalent hydrocarbon group, and B ¹¹ is a monovalent organic having a perfluoroalkyl group. D ¹¹ represents a monovalent organic group having a substituted or unsubstituted polystyrene chain having a degree of polymerization of 3 or more, a monovalent organic group having a substituted or unsubstituted alkyleneoxy group, a substituted or unsubstituted siloxane 1 represents a monovalent group selected from the group consisting of a monovalent organic group having a chain and a monovalent organic group having 12 or more carbon atoms.

  The diorganopolysiloxane may further have a repeating structural unit γ represented by the following formula (3).

In the above formula (3), R ¹³ and R ¹⁴ each independently represents a substituted or unsubstituted monovalent hydrocarbon group.

  Examples of the terminal group of the diorganopolysiloxane include a terminal group I having a structure represented by the following formula (4) and a terminal group II having a structure represented by the following formula (5).

In the above formulas (4) and (5), R ¹⁵ and R ¹⁶ each independently represents a substituted or unsubstituted monovalent hydrocarbon group, and E ¹¹ and E ¹² each independently represents a substituted or unsubstituted group. A substituted monovalent hydrocarbon group, a monovalent organic group having a perfluoroalkyl group, a monovalent organic group having a substituted or unsubstituted polystyrene chain having a polymerization degree of 3 or more, and a substituted or unsubstituted alkyleneoxy group. A monovalent group selected from the group consisting of a monovalent organic group having a monovalent organic group having a substituted or unsubstituted siloxane chain, and a monovalent organic group having 12 or more carbon atoms, E ¹¹ in the formula (4) is bonded to Si in the main chain (-Si-O-) of the repeating structural unit of the diorganopolysiloxane, and Si in the formula (5) is the diorgano Repeating of polysiloxane Bonds with O in the main chain (-Si-O-) of the structural unit.

  In the present invention, the organic group means a substituted or unsubstituted hydrocarbon group. In addition, examples of the hydrocarbon group include an alkyl group, an alkenyl group, an aryl group, and an arylalkenyl group.

Examples of the monovalent hydrocarbon group for R ^{11 to} R ¹⁶ include a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted aryl group, and a substituted or unsubstituted arylalkenyl group. Can be mentioned. These groups preferably have 1 to 30 carbon atoms, more preferably a methyl group or a phenyl group.

The monovalent organic group having a B ¹¹ perfluoroalkyl group is preferably a monovalent group having a structure represented by the following formula (6).

In the above formula (6), R ²¹ represents an alkylene group or an alkyleneoxyalkylene group, and a represents an integer of 3 or more.

Examples of the alkylene group include an ethylene group and a propylene group. As the alkylene oxyalkylene group, ethyleneoxyethylene group, oxyethylene oxypropylene group, a monovalent organic group having a polymerization degree of 3 or more substituted or unsubstituted polystyrene chain of the D ¹¹ of propylene oxypropylene group is A monovalent group having a structure represented by the following formula (7) is preferable.

In the above formula (7), R ³¹ represents a substituted or unsubstituted divalent hydrocarbon group, and R ³² and R ³³ each independently represents a substituted or unsubstituted alkyl group, or a substituted or unsubstituted group. W ³¹ represents a substituted or unsubstituted polystyrene chain having a degree of polymerization of 3 or more, R ³⁴ represents a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group, b Represents 0 or 1.

  As said bivalent hydrocarbon group, alkylene groups, such as a methylene group, ethylene group, a propylene group, are mentioned, It is preferable that it is C1-C10. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, and a butyl group. The aryl group is preferably unsubstituted, and examples thereof include a phenyl group.

The monovalent organic group having a substituted or unsubstituted alkyleneoxy group of D ¹¹ is preferably a monovalent group having a structure represented by the following formula (8).

In the above formula (8), R ⁴¹ and R ⁴² each independently represents a substituted or unsubstituted divalent hydrocarbon group, and R ⁴³ represents a hydrogen atom or a substituted or unsubstituted monovalent carbon group. Represents a hydrogen group, c represents 0 or 1, and d represents an integer of 1 to 300.

  Examples of the divalent hydrocarbon group include alkylene groups such as a methylene group, an ethylene group, and a propylene group, and arylene groups such as a phenylene group. Examples of the monovalent hydrocarbon group include alkyl groups such as a methyl group, an ethyl group, and a propyl group, and aryl groups such as a phenyl group. The d is preferably 5 or more.

The monovalent organic group having a substituted or unsubstituted siloxane chain of D ¹¹ is preferably a monovalent group having a structure represented by the following formula (9).

In the above formula (9), R ⁵¹ represents an alkylene group, an alkyleneoxy group, or an oxygen atom, and R ^{52 to} R ⁵⁶ each independently represents a substituted or unsubstituted alkyl group, or a substituted or unsubstituted group. E represents an integer of 3 or more.

  Examples of the alkylene group include an ethylene group and a propylene group. Examples of the alkyleneoxy group include an ethyleneoxy group and a propyleneoxy group. Examples of the alkyl group include a methyl group and an ethyl group. Examples of the aryl group include a phenyl group. The e is preferably 5 or more.

Examples of the monovalent organic group having 12 or more carbon atoms of D ¹¹ include alkyl groups such as n-dodecyl group, n-tetradodecyl group, n-hexadecyl group and n-octadecyl group. The number of carbon atoms is preferably 100 or less.

  Examples of the substituent that each of the above groups may have include a halogen atom such as a fluorine atom, a chlorine atom and an iodine atom, an alkyl group such as a methyl group, an ethyl group and a propyl group, and an aryl group such as a phenyl group. Can be mentioned.

  The number (average) of repeating structural units α represented by the above formula (1) in the diorganopolysiloxane is preferably 1 to 1000, and more preferably 10 to 200.

  The number (average) of repeating structural units α represented by the above formula (1) in the diorganopolysiloxane is preferably 1 to 1000, and more preferably 10 to 200.

  The number (average) of repeating structural units β represented by the above formula (2) in the diorganopolysiloxane is preferably 1 to 1000, and more preferably 5 to 100.

  The number (average) of repeating structural units γ represented by the above formula (3) in the diorganopolysiloxane is preferably 0 to 1000, and more preferably 100 to 200.

  The repeating structural unit possessed by the diorganopolysiloxane is only the repeating structural unit α represented by the above formula (1) and the repeating structural unit β represented by the above formula (2), or the repeating structural unit represented by the above formula (1). It is preferable that there are only the structural unit α, the repeating structural unit β represented by the above formula (2), and the repeating structural unit γ represented by the above formula (3).

  Sum (average) of the repeating structural unit α represented by the formula (1), the repeating structural unit β represented by the formula (2) and the repeating structural unit γ represented by the formula (3) in the diorganopolysiloxane. Is preferably from 2 to 2000, more preferably from 5 to 1000, and even more preferably from 20 to 500.

When the number of repeating structural units α represented by the above formula (1) is 2 or more, the plurality of R ¹¹ may be the same group or two or more different groups, and the plurality of B ¹¹ are the same. Or two or more different groups.

When the number of the repeating structural units β represented by the formula (2) is 2 or more, the plurality of R ¹² may be the same group or two or more different groups, and the plurality of D ¹¹ are the same. Or two or more different groups. D ¹¹ is a monovalent organic group having a substituted or unsubstituted polystyrene chain having a degree of polymerization of 3 or more, a monovalent organic group having a substituted or unsubstituted alkyleneoxy group, a substituted or unsubstituted siloxane, as described above. Any one of a monovalent organic group having a chain and a monovalent organic group having 12 or more carbon atoms, and when there are a plurality of D ¹¹ , at least one D ¹¹ is a substituted or unsubstituted group. A monovalent organic group having a siloxane chain is preferred.

When the number of repeating structural units γ represented by the formula (3) is 2 or more, the plurality of R ¹³ may be the same group or two or more different groups, and the plurality of R ¹⁴ are the same. Or two or more different groups.

The same applies to R ³² and R ^{33 in} the above formula (7), R ^{42 in} the above formula (8), and R ⁵² and R ⁵³ in the above formula (9).

Below, the specific example of the diorganopolysiloxane used for this invention is shown. However, the present invention is not limited to these specific examples. In addition, the following diorganopolysiloxanes (1-1) to (1-23) are all terminal groups I (E ¹¹ : methyl group) having the structure represented by the above formula (4) as terminal groups, and the following formulas terminal group ^II having a structure represented by ^{(5) (E 12, R} 15, R 16: methyl) having a.

  Among these, (1-1), (1-4), (1-5), (1-7), (1-10), (1-14), (1-15), (1- 22) is preferable, and (1-1), (1-5), (1-10), and (1-22) are particularly preferable.

  The weight average molecular weight of the diorganopolysiloxane used in the present invention is 1000 to 1000000, preferably 10,000 to 200000, more preferably 10,000 to 100,000, and more preferably 20000 to 40000. Is more preferable.

  Moreover, it is preferable that content of the fluorine atom in the diorganopolysiloxane used for this invention is 1-90 mass% with respect to the diorganopolysiloxane total mass, and is 5-60 mass% especially. It is preferable. If the fluorine atom content is less than 1% by mass, the releasability of the surface layer of the electrophotographic photosensitive member may not be sufficiently exhibited. If it exceeds 90% by mass, the binding in the surface layer of the electrophotographic photosensitive member may not be achieved. If the compatibility with the resin deteriorates or the anchor effect is not sufficiently obtained, it becomes easy to move to the surface, and if the surface of the electrophotographic photosensitive member is worn due to long-term use, a sufficient effect is obtained. It may not be possible.

  In general, since silicone oil and siloxane compounds have surface migration in the layer, when the surface of the electrophotographic photosensitive member is worn due to long-term use, many of these components are lost and sufficient. The effect cannot be obtained.

On the other hand, the diorganopolysiloxane used in the present invention has an anchoring effect on the binder resin of the surface layer of the electrophotographic photoreceptor, particularly because the side chain D ¹¹ has an anchoring effect on the surface. It is suppressed.

  Hereinafter, the configuration of the electrophotographic photosensitive member used in the present invention will be described.

  The electrophotographic photoreceptor used in the present invention has a photosensitive layer on a support.

  The support may be anything that has conductivity (conductive support), and is provided with a metal support such as aluminum or stainless steel, or a layer that imparts conductivity on metal, paper, plastic, or the like. And the like. Examples of the shape of the support include a cylindrical shape and a belt shape.

  Even if the photosensitive layer is a single layer type in which the charge transport material and the charge generation material are contained in the same layer, the layer is separated into a charge generation layer containing the charge generation material and a charge transport layer containing the charge transport material. A mold (function separation type) may be used, but a laminated type is preferable from the viewpoint of electrophotographic characteristics. The laminated photosensitive layer has a normal layer type photosensitive layer laminated in the order of the charge generation layer and the charge transport layer from the support side, and a reverse layer type photosensitive layer laminated in the order of the charge transport layer and the charge generation layer from the support side. However, the normal layer type is preferable from the viewpoint of electrophotographic characteristics.

  When the exposure light is laser light, a conductive layer may be provided on the support for the purpose of preventing interference fringes due to scattering and for the purpose of covering scratches on the support. The conductive layer can be formed by dispersing conductive particles such as carbon black and metal particles in a binder resin. The thickness of the conductive layer is preferably 5 to 40 μm, and more preferably 5 to 25 μm. The interference fringes can also be prevented by treating the surface of the support by cutting treatment, alumite treatment, dry blast treatment, wet blast treatment or the like.

  An intermediate layer having an adhesion function or a barrier function may be provided on the support or the conductive layer. The intermediate layer is formed by dissolving a resin such as polyamide, polyvinyl alcohol, polyethylene oxide, ethyl cellulose, casein, polyurethane, or polyether urethane in an appropriate solvent, and applying and drying the solution on a support or conductive layer. Can do. The thickness of the intermediate layer is preferably 0.05 to 5 μm, and more preferably 0.3 to 1 μm. Note that the intermediate layer is not necessarily required when the support surface is alumite-treated or when a conductive film by a sol-gel method is used.

  When the photosensitive layer is a normal type photosensitive layer, a charge generation layer is provided on the support, the conductive layer, or the intermediate layer.

  Examples of the charge generating substance include pigments such as selenium-tellurium, pyrylium, thiapyrylium dye, phthalocyanine, anthanthrone, dibenzpyrenequinone, trisazo, cyanine, azo (trisazo, disazo, monoazo), indigo, quinacridone, and asymmetric quinocyanine. Can be mentioned.

  The charge generation layer is composed of a charge generation material, 0.3 to 4 times (mass ratio) binder resin and solvent, homogenizer, ultrasonic dispersion, ball mill, vibration ball mill, sand mill, attritor, roll mill, liquid collision The dispersion can be formed by coating and drying the resulting dispersion, which is well dispersed by a type high-speed disperser. Note that the binder resin may be added after the charge generating material is dispersed, or the binder resin may not be used if the charge generating material has a film-forming property. The thickness of the charge generation layer is preferably 5 μm or less, and more preferably 0.1 to 2 μm.

  When the photosensitive layer is a normal type photosensitive layer, a charge transport layer is provided on the charge generation layer.

  Examples of the charge transport material include triarylamine compounds, hydrazone compounds, stilbene compounds, pyrazoline compounds, oxazole compounds, triallylmethane compounds, and thiazole compounds.

  The charge transport layer can be formed by dissolving the charge transport material and the binder resin with a solvent, and coating and drying the obtained coating solution. The charge transport layer is a surface layer of the electrophotographic photosensitive member. In this case, the charge transport material, the binder resin, and the diorganopolysiloxane can be dissolved in a solvent, and the resulting coating solution can be formed by coating and drying. The mass ratio between the charge transport material and the binder resin is preferably 5: 1 to 1: 5, and more preferably 3: 1 to 1: 3. The thickness of the charge transport layer is preferably 5 to 50 μm, more preferably 10 to 35 μm.

  Examples of the binder resin for the charge transport layer include thermoplastic resins and curable resins. Specifically, phenoxy resin, polyacrylamide resin, polyvinyl butyral resin, polyarylate resin, polysulfone resin, polyamide resin, acrylic resin, acrylonitrile resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, phenol resin, epoxy resin, polyester A resin, an alkyd resin, a polycarbonate resin, a polyurethane resin, or a copolymer containing two or more repeating units of these resins, such as a styrene-butadiene copolymer, a styrene-acrylonitrile copolymer, and a styrene-maleic acid copolymer. Can be mentioned. It can also be selected from organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene, and polyvinylpyrene.

  Of these, polycarbonate resins and polyarylate resins are preferred because they have good compatibility with the diorganopolysiloxane used in the present invention and can produce a good coating solution. In particular, the weight average molecular weight of the polycarbonate resin used in combination with the diorganopolysiloxane is preferably in the range of 20,000 to 300,000, and more preferably in the range of 50,000 to 150,000. The weight average molecular weight of the polyarylate resin used in combination with the diorganopolysiloxane is preferably in the range of 20,000 to 300,000, and more preferably in the range of 50,000 to 150,000.

  Moreover, as a polycarbonate resin, the polycarbonate resin which has a repeating structural unit shown by following formula (10) is preferable.

In the above formula (10), X ⁶⁰¹ is a single bond, a carbonyl group, an ether group, a thioether group, or a —CR ⁶⁰¹ R ⁶⁰² — group (R ⁶⁰¹ and R ⁶⁰² are each independently a hydrogen atom, substituted or unsubstituted substituted alkyl group, or a substituted or unsubstituted aryl group, or a substituted or unsubstituted cycloalkylidene group and R ⁶⁰¹ and R ⁶⁰² are formed by bonding.) indicates, R ⁶⁰¹ ~ R ⁶⁰⁴ and R ^{607 to} R ⁶¹⁰ each independently represent a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group.

Among these, X ⁶⁰¹ is preferably a single bond or a —CR ⁶⁰¹ R ⁶⁰² — group, and R ⁶⁰² , R ⁶⁰⁴ , R ⁶⁰⁶ , and R ⁶⁰⁹ are preferably hydrogen atoms.

  Moreover, as a polyarylate resin, the polyarylate resin which has a repeating structural unit shown by following formula (11) is preferable.

In the above formula (11), X ⁷⁰¹ is a single bond, a carbonyl group, an ether group, a thioether group, or a —CR ⁷⁰¹ R ⁷⁰² — group (R ⁷⁰¹ and R ⁷⁰² are each independently a hydrogen atom, substituted alkyl group, or a substituted or unsubstituted aryl group, or a substituted or unsubstituted cycloalkylidene group and R ⁷⁰¹ and R ⁷⁰² are formed by bonding.) indicates, R ⁷⁰¹ ~ R ⁷⁰⁴ and R ^{707 to} R ⁷¹⁴ each independently represent a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group.

Among these, X ⁷⁰¹ is preferably a single bond or a —CR ⁷⁰¹ R ⁷⁰² — group, and R ⁷⁰² , R ⁷⁰⁴ , R ⁷⁰⁷ and R ⁷⁰⁹ are preferably hydrogen atoms.

  In the above formulas (10) and (11), examples of the halogen atom include a fluorine atom, a chlorine atom, and an iodine atom. Examples of the alkyl group include a methyl group, an ethyl group, and a propyl group. Examples thereof include a phenyl group and a naphthyl group, and examples of the alkylidene group include a cyclohexylidene group.

  Examples of the substituent that each of these groups may have include a halogen atom such as a fluorine atom, a chlorine atom and an iodine atom, an alkyl group such as a methyl group, an ethyl group and a propyl group, and an aryl group such as a phenyl group. Can be mentioned.

  Specific examples of the repeating structural unit represented by the above formula (10) are shown below.

  Among these, (6-1), (6-3), (6-4), (6-10), and (6-16) are preferable, and (6-1) and (6-3) are particularly preferable. , (6-16) is more preferable.

  Specific examples of the repeating structural unit represented by the above formula (11) are shown below.

  Among these, (7-2), (7-3), (7-6), (7-13), (7-22), and (7-23) are preferable, and in particular (7-3) , (7-13) and (7-22) are more preferable.

  Solvents used in the charge transport layer and surface layer preparation paints have various properties such as high solubility, suitable boiling point, no remaining in the photosensitive layer, and no adverse effects on electrophotographic properties as impurities. There is a need. For this reason, as a result of various studies, it has been found that aromatic hydrocarbon solvents are most suitable as the solvent for the surface layer containing the specific diorganopolysiloxane according to the present invention.

  In general, there are many aromatic hydrocarbons having a substituent such as toluene, xylene, anisole, benzyl alcohol, phenol, cresol, monochlorobenzene and dichlorobenzene, in addition to unsubstituted ones such as benzene. This aromatic hydrocarbon is applied as a constituent solvent after coating, and then undergoes a process of removing the solvent by evaporation at high temperature drying. Therefore, if the solvent is difficult to evaporate, it exists as a residual solvent in the photosensitive layer. If it is a coating solution for the surface layer, it becomes an obstacle to wear resistance. Therefore, since the aromatic hydrocarbon according to the present invention has a boiling point far from the normal temperature, it is not suitable as a solvent for the photoreceptor coating solution, so the boiling point is preferably 80 degrees or more, more preferably the boiling point. It is preferably 90 degrees or more.

  Examples of the aromatic hydrocarbon having the boiling point as described above include benzene, toluene, xylene, anisole, chlorobenzene and the like. However, benzene is not included in the aromatic hydrocarbon of the present invention from the viewpoint of knowledge of adverse effects on the human body. Chlorobenzene should only be used in exceptional manufacturing processes where a solvent recovery system is in place if pursuing the establishment of a dehalogenated solvent.

  Among these aromatic hydrocarbons, the range of 135 to 145 ° C., which is the boiling point of xylene and structural isomers thereof, is suitable as a high boiling point solvent for the coating solution for the charge transport layer and not a component that tends to remain. Considered temperature range.

  In order to uniformly apply the charge transport layer by dip coating, it is preferable to use a low boiling point solvent in combination with the above high boiling point solvent. As a solvent combined with the above aromatic hydrocarbon solvent, dimethoxymethane is used. Ethylene glycol dimethyl ether, tetrahydrofuran and the like are suitable. At this time, the mixing ratio of dimethoxymethane, ethylene glycol dimethyl ether, tetrahydrofuran and the above aromatic hydrocarbon solvent can be selected from the relationship between ease of whitening and sagging of the film thickness after drying. More preferable mixing satisfying the above condition is when the mixing ratio of dimethoxymethane / aromatic hydrocarbon is 20 to 60/40 to 80 (weight ratio).

  When the surface layer of the electrophotographic photosensitive member is a charge transport layer, the content of the diorganopolysiloxane in the charge transport layer is preferably 0.01 to 20 parts by mass with respect to the total mass of the charge transport layer, In particular, 0.1-10.0 mass parts is more preferable. If the content is too small, it is difficult to obtain the effect of the present invention. If the content is too large, carrier trapping may occur, and potential fluctuation may occur.

  FIG. 1 shows a schematic configuration example of the image forming method, but this is an example and does not limit the present invention.

  The image forming method shown in FIG. 1 includes a photosensitive member 1 that is an image carrier for transferring a toner image onto a transfer material, a charging roller 2 that is a charging member that uniformly charges the photosensitive member 1, and a photosensitive member. 1 and a control means for controlling the level of the voltage applied to the charging roller 2.

  The apparatus also stores a laser scanner 3 that forms an electrostatic latent image on the photoreceptor 1, a developing device 4 that develops the formed electrostatic latent image, and a transfer material that transfers the developed toner image. A cassette 5, a paper feed roller 6 that feeds a transfer material from the cassette 5, and a timing roller 7 that transfers the transfer material fed by the paper feed roller 6 to the photoconductor 1 with good timing.

  The apparatus further includes a transfer roller 8 that presses the transfer material against the photosensitive member 1 to transfer the toner image onto the transfer material, a fixing device 9 that fixes the transfer material onto which the toner image is transferred, and the toner image is fixed. A discharge roller 10 that discharges the transferred transfer material to the outside of the image forming apparatus, a discharge tray 11 that receives the transferred transfer material, and a cleaner 12 that cleans the remaining transfer toner are provided.

  As will be described later, the image forming method shown in FIG. 5 has a structure in which a process cartridge that integrally supports the photosensitive member 1, the charging roller 2, and the cleaner 12 can be attached and detached.

  Further, the laser scanner 3 performs a raster scan based on the image signal and performs exposure. The laser scanner 3 scans the flashing of the semiconductor laser with a polygon scanner and irradiates the photoreceptor 1 with an optical system.

  The developing unit 4 performs jumping development, two-component development, FEED development, and the like, and is used in combination with reversal development in which a laser is turned on to attach toner to the lower potential of the latent image. .

  Further, the transfer roller 8 is an elastic body having low conductivity, and is electrostatically transferred by a bias electric field at a nip portion formed by the photoreceptor 1 and the transfer roller 8.

  Next, the operation of the image forming method shown in FIG. 1 will be described. First, a voltage is applied to the charging roller 2. Then, uniform charging is performed on the photosensitive member 1 by the charging roller 2.

  Next, the laser scanner 3 performs raster scanning based on the image signal and performs exposure. The laser scanner 3 scans the flashing of the semiconductor laser with a polygon scanner and irradiates the photosensitive drum with an optical system. Thus, an electrostatic latent image is formed on the photoreceptor 1.

  The formed electrostatic latent image is developed by the developing device 4. For development, jumping development or the like is used, and recording is performed in combination with reversal development in which a laser is turned on to attach toner to the lower potential of the latent image. In this state, when a print signal is sent from the host computer, the transfer material stored in the cassette 5 is fed one by one by the paper feed roller 6.

  Next, the transfer material is transferred to the photosensitive drum side by the timing roller 7. In this way, the toner image is transferred onto the transfer material by the transfer roller 8 in synchronization with the image signal. The transfer material onto which the toner image has been transferred is fixed by the fixing device 9, sent to the outside of the apparatus by the paper discharge roller 10, and discharged to the paper discharge tray 11.

  On the other hand, the transfer residual toner is removed by the cleaning blade of the cleaner 12. Further, when the transfer residual toner is removed, in order to form the next image, the photosensitive member 1 is uniformly charged and the above operation is performed until all the images are transferred onto the transfer material. repeat.

  The electrophotographic photosensitive member of the present invention can be used not only in electrophotographic copying machines but also widely in electrophotographic application fields such as laser beam printers, CRT printers, LED printers, liquid crystal printers, and laser plate making.

  The weight average molecular weight (Mw) of the polyarylate resin is measured according to a conventional method. Put the sample in THF, let stand for several hours, and then shake well to mix well with THF (until the sample is no longer united) and let stand for more than 12 hours. Then, a sample of GPC was passed through a sample processing filter (pore size 0.45 to 0.5 μm, for example, Mysori Disc H-25-5 manufactured by Tosoh Corp., Excro Disc 25CR manufactured by Gelman Science Co., Ltd., etc.). And The sample concentration is adjusted so that the resin component is 0.5 to 5 mg / ml.

The produced sample is measured by the following method. The column is stabilized in a 40 ° C. heat chamber, and THF as a solvent is allowed to flow through the column at this temperature at a flow rate of 1 ml / min, and about 10 μl of a THF sample solution is injected and measured. In measuring the molecular weight of a sample, the molecular weight distribution of the sample is calculated from the relationship between the logarithmic value of a calibration curve prepared from several types of monodisperse polystyrene standard samples and the number of counts. As a standard polystyrene sample for preparing a calibration curve, for example, one having a molecular weight of about 10 ² to 10 ⁷ manufactured by Tosoh Corporation or Showa Denko is used, and at least about 10 standard polystyrene samples are suitably used. is there. An RI (refractive index) detector is used as the detector. As the column, it is preferable to combine a plurality of commercially available polystyrene gel columns. For example, combinations of shodex GPC KF-801, 802, 803, 804, 805, 806, 807, 800P manufactured by Showa Denko, and TSKgel G1000H manufactured by Tosoh Corporation (H _XL ), G2000H (H _XL ), G3000H (H _XL ), G4000H (H _XL ), G5000H (H _XL ), G6000H (H _XL ), G7000H (H _XL ), and TSK guardcolumn can be given.

  Hereinafter, the present invention will be described in more detail with reference to specific examples. However, the present invention is not limited to these examples. In the examples, “part” means “part by mass”.

  First, the diorganopolysiloxane used in the present invention can be synthesized as follows.

(Synthesis Example 1)
In a flask, 3.23 g of polysiloxane having the following repeating structural units α, β, γ,

ｍ−キシレンヘキサフルオライド８０ｇとを混合し、徐々に加熱した。さらに、８０℃で６時間反応を続けた。次いで、１４０℃の条件下で２０Ｔｏｒｒまで減圧して、溶媒や低沸点成分を除去した。 20 ppm of chloroplatinic acid (5% isopropyl alcohol solution), polystyrene having a structure represented by the following formula (n: average 25) 18.9 g,

80 g of m-xylene hexafluoride was mixed and gradually heated. Further, the reaction was continued at 80 ° C. for 6 hours. Next, the pressure was reduced to 20 Torr under the condition of 140 ° C. to remove the solvent and low boiling point components.

Thus, when the obtained reaction product was analyzed by < ²⁹ > Si-NMR, < ¹³ > C-NMR, and FT-IR, it became clear that it was diorganopolysiloxane (1-1).

に変更した以外は、合成例１と同様にして合成を行った。 (Synthesis Example 2)
In Synthesis Example 1, 13.4 g of polystyrene having a structure represented by the following formula (n: average 25)

The synthesis was carried out in the same manner as in Synthesis Example 1 except that

When the obtained reaction product was analyzed by ²⁹ Si-NMR, ¹³ C-NMR and FT-IR, it was found to be diorganopolysiloxane (1-4).

  Diorganopolysiloxanes having other structures used in the present invention can also be synthesized in the same manner as in Synthesis Examples 1 and 2.

(Example 1)
An aluminum cylinder having a diameter of 30 mm and a length of 357 mm is used as a support, and a conductive layer coating solution composed of the following materials is applied on the support by dip coating, thermosetting at 140 ° C. for 30 minutes, and a film thickness of 15 μm. The conductive layer was formed.

  Next, a solution prepared by dissolving 3 parts of N-methoxymethylated nylon (registered trademark) and 3 parts of copolymer nylon (registered trademark) in a mixed solvent of 65 parts of methanol and 30 parts of n-butanol is immersed on the conductive layer. The intermediate layer having a film thickness of 1.0 μm was formed by applying and drying by a coating method.

  Next, 4 parts of a charge generation material (CGM-1) represented by the following structure and 70 parts of tetrahydrofuran are dispersed for 10 hours in a sand mill apparatus using glass beads having a diameter of 1 mm, and then polyvinyl butyral resin (S-REC BLS, manufactured by Sekisui Chemical Co., Ltd.). ) A solution of 2 parts in 20 parts of tetrahydrofuran was added and dispersed for another 2 hours. Further, the glass beads were separated, and 100 parts of cyclohexanone was added to prepare a dispersion for the charge generation layer. This dispersion was dip-coated on the intermediate layer and dried at 80 ° C. for 10 minutes to form a charge generation layer having a thickness of 0.2 μm.

（ＣＧＭ―１）

(CGM-1)

  Next, a charge transport layer coating solution composed of the following materials was dip-coated on the charge generation layer and dried at 120 ° C. for 1 hour to form a charge transport layer having a thickness of 30 μm.

電荷輸送物質：下記式で示される構造を有するアミン化合物Ｂ １部

ジオルガノポリシロキサン：ジオルガノポリシロキサン（１−４）（重量平均分子量：３６０００） ０．１８部
溶剤：ｐ−キシレン／ジメトキシメタン＝６／４ １００部
このようにして、電荷輸送層が表面層である電子写真感光体を作製した。 Binder resin: Polyarylate resin having a repeating structural unit represented by the above formula (7-2) (weight average molecular weight 128000) 10 parts Charge transport material: Amine compound A having a structure represented by the following formula: 7 parts

Charge transport material: 1 part of amine compound B having a structure represented by the following formula

Diorganopolysiloxane: Diorganopolysiloxane (1-4) (weight average molecular weight: 36000) 0.18 parts Solvent: p-xylene / dimethoxymethane = 6/4 100 parts In this way, the charge transport layer is a surface layer. An electrophotographic photosensitive member was prepared.

  Next, evaluation will be described.

  A Canon Co., Ltd. copier GP405 was used as an evaluation apparatus. Note that “GP405” uses a contact charging roller in contact with the surface of the photoreceptor as a primary charging member, and a DC voltage: −750 V, an AC voltage: a peak-to-peak voltage of 1.85 kV, and a frequency of 1834 Hz are applied to the charging roller. An image forming apparatus having a configuration in which a photoconductor is primarily charged by application. The room to be evaluated was set to a temperature of 23 ° C./humidity of 50% RH, a dark part potential Vd = −700V, and a light part potential Vl = −200V. Furthermore, 10,000 sheets of images with a printing ratio of 6% were copied in an intermittent mode (10 seconds / copy interval) in which A4-size plain paper is stopped once for each copy. The surface potential was measured after the initial and 10,000 copies were repeatedly copied, and the difference in light portion potential (ΔVl) was examined. In addition, when ΔVl was calculated by (absolute value of bright part potential after 10,000 sheets) − (absolute value of initial bright part potential), ΔVl was 5V, which was a favorable result. At the same time, the toner transfer rate was measured. The measurement method is to measure the mass of the process unit and the developing unit on which the photosensitive member is mounted, after the endurance and after the endurance, respectively, and after printing 500 sheets using a test chart with a printing ratio of 6%, the process unit is again The mass of the developing device was measured and evaluated.

  The transfer rate was calculated by the following formula.

Transfer rate (%) = (developer reduction amount−process unit increase amount) / (developer reduction amount) × 100
The result was 93% at the initial stage, 91% after 10,000 sheets, and good results were obtained.

  In addition, the evaluation was performed in the same manner as described above with the environment being a high-temperature and high-humidity environment of 32.5 ° C./85% RH. As a result, ΔVl was 10 V, the initial transfer rate was 92%, and a good result was obtained 90% after 10,000 sheets.

  The images were also evaluated according to the following criteria.

Images: Originals containing lines and letters were used, and initial and post-durability images were evaluated according to the following criteria using visual or magnified microscopes.
A: Both the character image and the line image are faithfully reproduced finely.
○: Some irregularities or voids occur in the details, but it is at a level that causes no problem with visual inspection.
(Triangle | delta): It is a level which can understand disorder and a hollow also visually.
×: Many disturbances and hollows occur, and the document is not reproduced.

  The above evaluation results are shown in Table 25.

(Example 2)
In Example 1, an electrophotographic photosensitive member was produced in the same manner as in Example 1-1, except that the amount of diorganopolysiloxane in the charge transport layer coating solution was changed from 0.18 to 0.9. Evaluation was performed. The evaluation results are shown in Table 25.

(Example 3)
Example 2 and Example 2 except that diorganopolysiloxane (1-4) in the coating solution for charge transport layer was changed to diorganopolysiloxane (1-17) (weight average molecular weight: 38000). Similarly, an electrophotographic photosensitive member was produced and evaluated. The evaluation results are shown in Table 25.

Example 4
An electrophotographic photoreceptor was prepared and evaluated in the same manner as in Example 1 except that the charge transport layer coating solvent was changed to o-xylene / dimethoxymethane = 5/5 in Example 1. The evaluation results are shown in Table 25.

(Example 5)
In Example 2, an electrophotographic photosensitive member was produced and evaluated in the same manner as in Example 1-2 except that the coating solvent for the charge transport layer was changed to m-xylene / dimethoxymethane = 4/6. The evaluation results are shown in Table 25.

(Example 6)
In Example 1, the polyarylate resin (weight average molecular weight 128000) having the repeating structural unit represented by the above formula (7-2) in the coating solution for charge transport layer is repeatedly represented by the above formula (6-3). An electrophotographic photoreceptor was prepared and evaluated in the same manner as in Example 1 except that the structural unit was changed to polycarbonate resin (weight average molecular weight 106000). The evaluation results are shown in Table 25.

(Example 7)
In Example 6, an electrophotographic photosensitive member was prepared and evaluated in the same manner as in Example 6 except that the amount of diorganopolysiloxane in the coating solution for the charge transport layer was changed from 0.18 to 0.9. went. The evaluation results are shown in Table 25.

(Comparative Example 1)
In Example 1, an electrophotographic photosensitive member was produced and evaluated in the same manner as in Example 1 except that diorganopolysiloxane was not added to the charge transport layer coating solution. The evaluation results are shown in Table 25.

(Comparative Example 2)
In Example 1-1, electrophotography was performed in the same manner as in Example 1 except that the diorganopolysiloxane in the charge transport layer coating solution was changed to silicone oil (trade name: KF96, manufactured by Shin-Etsu Silicone Co., Ltd.). A photoconductor was prepared and evaluated. The evaluation results are shown in Table 25.

(Comparative Example 3)
In Example 1, an electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that the diorganopolysiloxane in the charge transport layer coating solution was changed to a silicone compound (trade name: GS101, manufactured by Toagosei Co., Ltd.). Were prepared and evaluated. The evaluation results are shown in Table 25.

(Comparative Example 4)
In Example 1, an electrophotographic photosensitive member was produced and evaluated in the same manner as in Example 1 except that the coating solvent for the charge transport layer was changed to dichloromethane / dimethoxymethane = 4/6. The evaluation results are shown in Table 25.

The figure which shows the schematic structural example of the image forming method which concerns on this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Contact charging member 3 Laser scanner 4 Developing device 5 Cassette 6 Paper feed roller 7 Timing roller 8 Transfer roller 9 Fixing device 10 Paper discharge roller 11 Paper discharge tray 12 Cleaner

Claims (3)

In the electrophotographic photosensitive member having a photosensitive layer on a conductive support, the surface layer of the electrophotographic photosensitive member is at least a binder resin, a repeating structural unit α represented by the following formula (1), and the following formula (2). Having a repeating structural unit β represented by

An electrophotography formed by applying and drying a solution containing a diorganopolysiloxane having a weight average molecular weight of 1,000 to 1,000,000 and an aromatic hydrocarbon solvent having a boiling point of 80 ° C. or higher. Photoconductor.   The electrophotographic photosensitive member according to claim 1, wherein the binder resin is a polyarylate resin or a polycarbonate resin.   The electrophotographic photoreceptor according to claim 1 or 2, wherein the aromatic hydrocarbon is at least one selected from xylene and structural isomers thereof.

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