JP2014059411A - Electrophotographic photoreceptor, and image forming apparatus and image forming method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor capable of forming good electrophotographic images stably for a long period, and an image forming apparatus and an image forming method using the electrophotographic photoreceptor.SOLUTION: An electrophotographic photoreceptor is provided having at least a photosensitive layer and a protective layer formed in order on a conductive support; and the protective layer contains a composition obtained by reacting metal oxide fine particles having a polymerizable unsaturated group on the surface with a polymerizable compound, fluorine-based resin particles, and a charge transport material represented by the following general formula (1).

Description

  The present invention relates to an electrophotographic photosensitive member used for electrophotographic image formation, an image forming apparatus and an image forming method using the electrophotographic photosensitive member, and more specifically, an electrophotographic method used in the field of copying machines and printers. The present invention relates to an electrophotographic photosensitive member used for image formation, an image forming apparatus using the electrophotographic photosensitive member, and an image forming method.

  In recent years, organic photoreceptors containing organic photoconductive materials have been widely used as electrophotographic photoreceptors. Organic photoconductors have great advantages such as wide selection of materials, excellent environmental suitability and low production costs compared to inorganic photoconductors such as selenium photoconductors and amorphous silicon photoconductors. In recent years, electrophotographic photoreceptors have become the mainstream in place of inorganic photoreceptors.

  On the other hand, an electrophotographic photosensitive member (hereinafter also simply referred to as a photosensitive member) is directly subjected to electrical or mechanical external force due to charging, exposure, development, transfer, cleaning, etc., so that it is charged even when image formation is repeated. There is a demand for durability to maintain stability, such as stability and potential retention.

  In general, in electrophotography or electrostatic recording, an electrostatic latent image is formed on an image carrier such as a photosensitive drum, and the electrostatic latent image is visualized using toner as a developer. To do. Then, an image is formed on the recording paper (recording material, recording medium, paper) through the transfer process and fixing process of the visualized toner image. In such an image forming system, the residual toner remains on the image carrier after the normal transfer process. Therefore, a cleaning unit is provided to clean the residual toner.

  Here, various types of cleaning means are known. A typical example is a blade cleaning system in which a cleaning blade using a contact plate having elasticity is disposed in contact with the image carrier, and the residual toner on the image carrier is scraped off by the cleaning blade. Can do. In this blade cleaning system, the surface of the image bearing member such as the photosensitive drum is abutted and rubbed, so that the edge that scrapes off the toner in the cleaning blade is worn out.

  For example, in a low / medium speed machine, a contact charging type charging unit such as a charging roller is generally used as a charging unit. The reason why such a contact charging type charging unit is used is that the generation of ozone is extremely small compared to the non-contact charging type charging unit, and it is environmentally friendly. Further, since an ozone filter and an air blow are not required, downsizing and cost reduction can be easily realized.

  On the other hand, there is a problem that the amount of discharge product adhering to the photosensitive drum is much larger than that of the non-contact charging type charging means. The cause is that the absolute amount of discharge products is smaller in the contact charging method than in the non-contact charging method, but the discharge region is very close to the photosensitive drum. . Therefore, in an image forming apparatus using a contact charging type charging unit, it is not easy to remove discharge products during blade cleaning, and it is necessary to increase the contact pressure of the cleaning blade to the photosensitive member. As a result, there arises a problem that the cleaning blade is worn and chipped due to an increase in the friction coefficient, and the torque of the photosensitive member drive system is increased.

  In order to solve such a problem, for example, in Patent Document 1, a protective layer of a cross-linked cured resin is provided on the photosensitive layer of the photoconductor, and the protective layer is introduced by introducing fluorine atom-containing particles into the protective layer. A method for reducing surface energy and improving cleaning properties is disclosed.

  In addition, as described in Patent Document 2, a technique for suppressing an increase in friction by reattaching toner after being scraped off by a cleaning blade to a photosensitive member has been proposed.

JP 2003-66641 A JP 2006-276158 A

  However, as a result of investigations by the present inventors, it has been found that it is difficult to sufficiently suppress the increase in friction between the photosensitive member and the cleaning blade even with the technique described in the above document.

  Therefore, the present inventors used an image forming apparatus having a photosensitive member having a protective layer of a cross-linked cured resin and a charging means of a contact charging method, in order to suppress chipping of the cleaning blade due to an increase in the coefficient of friction. In image formation, attempts have been made to improve the cleaning properties of the photoreceptor by incorporating fluororesin fine particles as external additives in the toner. However, the improvement of the cleaning property is not sufficient, and furthermore, a phenomenon such as “blade slipping” in which the external additive contained in the toner passes through the blade and remains on the photosensitive member is likely to occur. all right. Then, it has been found that the charging means is contaminated by such slipping through the blade and the charging property is deteriorated. In this case, the photosensitive member cannot be uniformly charged, which causes unevenness in the image.

  Therefore, the present invention suppresses an increase in friction between the photosensitive member and the cleaning blade, improves the charging property of the charging means, and can stably form a good electrophotographic image in the long term. It is an object of the present invention to provide a photoreceptor and an image forming apparatus using the same.

  In view of the above problems, the present inventors have made extensive studies. In the process, in an electrophotographic photosensitive member in which at least a photosensitive layer and a protective layer are sequentially formed on a conductive support, polymerization is performed with metal oxide fine particles having a polymerizable unsaturated group on the surface in the protective layer. The present invention has been completed by finding that the above-mentioned problems can be solved by containing a composition obtained by reacting a functional compound, fluororesin fine particles, and a specific charge transporting substance.

  That is, the present invention is achieved by using an organic photoreceptor, an image forming apparatus, and an image forming method having the following configurations.

1. In an electrophotographic photosensitive member formed by sequentially forming at least a photosensitive layer and a protective layer on a conductive support,
A composition obtained by reacting metal oxide fine particles having a polymerizable unsaturated group on the surface with a polymerizable compound, fluorine resin fine particles, and a charge represented by the following general formula (1): An electrophotographic photoreceptor comprising a transporting substance.

(In General Formula (1), R ₁ , R ₂ , R ₃ , and R ₄ each represent a hydrogen atom, an alkyl group having 1 to 7 carbon atoms, or an alkoxy group having 1 to 7 carbon atoms, and k, l, n Represents an integer of 1 to 5, and m represents an integer of 1 to 4. In addition, when there are a plurality of k, l, m, and n, these groups may be the same or different.
2. 2. The electrophotographic photosensitive member according to 1 above, wherein the addition amount of the fluororesin fine particles is 5 to 70 parts by mass with respect to 100 parts by mass of the resin component in the protective layer.

  3. 3. The electrophotographic photosensitive member according to 1 or 2, wherein the fluororesin fine particles have an average primary particle size of 0.01 to 1 μm.

4). The electrophotographic photosensitive member according to any one of items 1 to 3,
Contact charging type charging means for superimposing AC;
An image forming apparatus comprising:

  5. 5. An image forming method, wherein an electrophotographic image is formed using the image forming apparatus described in 4 above.

  According to the photoreceptor of the present invention, the coefficient of friction on the surface of the photoreceptor can be kept low. Therefore, wear and chipping of the cleaning blade during blade cleaning are suppressed, and the torque of the photosensitive member drive system is unlikely to increase. Furthermore, contamination of the charging means due to the blade slipping through the toner external additive can be suppressed, and the charging property of the charging means can be improved. As a result, a good electrophotographic image can be formed stably over the long term.

1 is a cross-sectional configuration diagram of an image forming apparatus showing an embodiment of the present invention. 1 is a cross-sectional configuration diagram of a color image forming apparatus showing an embodiment of the present invention.

  Hereinafter, the present invention will be described in detail.

  The electrophotographic photosensitive member of the present invention is an electrophotographic photosensitive member in which at least a photosensitive layer and a protective layer are sequentially formed on a conductive support, and the protective layer is a metal oxide having a polymerizable unsaturated group on the surface. It contains a composition obtained by reacting product fine particles with a polymerizable compound, fluorine resin fine particles, and a charge transporting substance represented by the general formula (1).

  Since the electrophotographic photosensitive member of the present invention has the above-described configuration, friction with the cleaning blade can be suppressed in an image forming apparatus having a contact charging type charging unit. Therefore, it is possible to suppress wear and chipping of the cleaning blade and increase in torque of the photosensitive member drive system. Furthermore, it is possible to suppress blade slipping of toner during blade cleaning. For these reasons, the cleaning property of the photoconductor can be improved and the chargeability of the photoconductor can be improved. Therefore, stable and long-term electrophotographic image formation can be performed.

  Hereinafter, the configuration of the electrophotographic photoreceptor of the present invention will be described.

[Protective layer]
The protective layer of the electrophotographic photosensitive member of the present invention comprises a composition obtained by reacting a metal oxide fine particle having a polymerizable unsaturated group on its surface with a polymerizable compound, fluorine-based resin fine particles, and the general formula ( 1) a charge transporting substance represented by In the photoconductor having such a configuration, the coefficient of friction on the surface of the photoconductor is kept low.

  Since the protective layer of the electrophotographic photoreceptor of the present invention is provided with a polymerizable unsaturated group on the surface of the metal oxide fine particles, an addition reaction is performed between the polymerizable unsaturated group and the polymerizable compound, A composition having a structure in which metal oxide fine particles and a polymer are molecularly bonded is formed.

[Metal oxide fine particles having polymerizable unsaturated groups on the surface]
The metal oxide fine particles used in the present invention may be any metal oxide fine particles including transition metals, such as silica (silicon oxide), magnesium oxide, zinc oxide, lead oxide, alumina (aluminum oxide). ), Metal oxide fine particles such as zirconium oxide, tin oxide, titania (titanium oxide), niobium oxide, molybdenum oxide, vanadium oxide, etc., among which tin oxide, titanium oxide, zinc oxide, and alumina are preferable.

Preferably, the metal oxide fine particles have a volume resistivity of 1 × 10 ³ to 1 × 10 ¹¹ Ω · cm. The volume resistivity (Ω · cm) of the metal oxide fine particles is obtained as follows.

  An electrical resistance is generally used as a measure of the conductivity of a substance. A value indicating this resistance per unit volume (1 cm × 1 cm × 1 cm) is a volume resistivity (unit Ω · cm).

  That is, it is obtained by passing a constant current I (A) through the cross-sectional area W × t and measuring the potential difference V (V) between the electrodes separated by the distance L.

Definition of volume resistivity (Ω · cm) Cross-sectional area = W x t
Resistance R = V / I
Volume resistivity VR (Ω · cm) = (W × t / L) × (V / I)
The volume resistivity (Ω · cm) of the metal oxide fine particles described in the present invention is such that a metal oxide fine particle or the like is filled in a container having electrodes arranged in parallel at intervals of 2 mm, and the potential difference between both electrodes is 500 V. The DC resistance was measured with a 4329A High Resistance Meter manufactured by Yokogawa Hewlett-Packard Co., Ltd.

  The method for producing the metal oxide fine particles is not particularly limited, and particles produced by a known production method can be used.

  The number average primary particle size of the metal oxide fine particles is preferably in the range of 1 to 300 nm. Especially preferably, it is 3-100 nm, More preferably, it is 5-40 nm.

  The number average primary particle size of the metal oxide fine particles is a photographic image (excluding aggregated particles) obtained by taking an enlarged photograph of 10,000 times with a scanning electron microscope (manufactured by JEOL Ltd.) and randomly capturing 300 particles with a scanner. A) automatic image processing analyzer LUZEX AP (Nireco Corp.) software version Ver. The number average primary particle size was calculated using 1.32.

  The metal oxide fine particles have a polymerizable unsaturated group on the surface. The metal oxide fine particles having a polymerizable unsaturated group on the surface are not particularly limited, but are preferably metal oxide fine particles surface-treated with a treating agent having a reactive organic group.

  As the treating agent having a reactive organic group, a surface treating agent having reactivity with a hydroxyl group or the like existing on the surface of the metal oxide fine particles (a silane coupling agent, a titanium coupling agent, etc.) is used. Those having a functional group are preferred. The radical polymerizable functional group can react with a curable monomer having a polymerizable unsaturated group to form a strong protective film. Examples of the radical polymerizable functional group include a vinyl group, an acryloyl group, and a methacryloyl group, and silane coupling agents having these radical polymerizable functional groups are preferable. Examples of the surface treatment agent as described above include compounds as described below.

_{S-1: CH 2 = CHSi} (CH 3) (OCH 3) 2
_{S-2: CH 2 = CHSi} (OCH 3) 3
S-3: CH ₂ = CHSiCl _{3
S-4: CH 2 = CHCOO} (CH 2) 2 Si (CH 3) (OCH 3) 2
_{S-5: CH 2 = CHCOO} (CH 2) 2 Si (OCH 3) 3
_{S-6: CH 2 = CHCOO} (CH 2) 2 Si (OC 2 H 5) (OCH 3) 2
_{S-7: CH 2 = CHCOO} (CH 2) 3 Si (OCH 3) 3
_{S-8: CH 2 = CHCOO} (CH 2) 2 Si (CH 3) Cl 2
_{S-9: CH 2 = CHCOO} (CH 2) 2 SiCl 3
_{S-10: CH 2 = CHCOO} (CH 2) 3 Si (CH 3) Cl 2
S-11: CH ₂ = CHCOO (CH ₂ ) ₃ SiCl _{3
S-12: CH 2 = C} (CH 3) COO (CH 2) 2 Si (CH 3) (OCH 3) 2
_{S-13: CH 2 = C} (CH 3) COO (CH 2) 2 Si (OCH 3) 3
_{S-14: CH 2 = C} (CH 3) COO (CH 2) 3 Si (CH 3) (OCH 3) 2
_{S-15: CH 2 = C} (CH 3) COO (CH 2) 3 Si (OCH 3) 3
_{S-16: CH 2 = C} (CH 3) COO (CH 2) 2 Si (CH 3) Cl 2
_{S-17: CH 2 = C} (CH 3) COO (CH 2) 2 SiCl 3
_{S-18: CH 2 = C} (CH 3) COO (CH 2) 3 Si (CH 3) Cl 2
_{S-19: CH 2 = C} (CH 3) COO (CH 2) 3 SiCl 3
_{S-20: CH 2 = CHSi} (C 2 H 5) (OCH 3) 2
_{S-21: CH 2 = C} (CH 3) Si (OCH 3) 3
_{S-22: CH 2 = C} (CH 3) Si (OC 2 H 5) 3
_{S-23: CH 2 = CHSi} (OCH 3) 3
_{S-24: CH 2 = C} (CH 3) Si (CH 3) (OCH 3) 2
_{S-25: CH 2 = CHSi} (CH 3) Cl 2
_{S-26: CH 2 = CHCOOSi} (OCH 3) 3
_{S-27: CH 2 = CHCOOSi} (OC 2 H 5) 3
_{S-28: CH 2 = C} (CH 3) COOSi (OCH 3) 3
_{S-29: CH 2 = C} (CH 3) COOSi (OC 2 H 5) 3
_{S-30: CH 2 = C} (CH 3) COO (CH 2) 3 Si (OC 2 H 5) 3
_{S-31: CH 2 = CHCOO} (CH 2) 2 Si (CH 3) 2 (OCH 3)
_{S-32: CH 2 = CHCOO} (CH 2) 2 Si (CH 3) (OCOCH 3) 2
_{S-33: CH 2 = CHCOO} (CH 2) 2 Si (CH 3) (ONHCH 3) 2
_{S-34: CH 2 = CHCOO} (CH 2) 2 Si (CH 3) (OC 6 H 5) 2
_{S-35: CH 2 = CHCOO} (CH 2) 2 Si (C 10 H 21) (OCH 3) 2
_{S-36: CH 2 = CHCOO} (CH 2) 2 Si (CH 2 C 6 H 5) (OCH 3) 2
Among the above, S-4 to S-7, which are compounds in which the acryloyl group has an ether bond and has a methoxy group, and S-12 to S-, which are compounds in which the methacryloyl group has an ether bond and has a methoxy group at the terminal 15 and S-24 are more preferred.

  Moreover, as a surface treating agent, you may use the silane compound which has the reactive organic group which can be radically polymerized other than said S-1 to S-36. These surface treatment agents can be used alone or in admixture of two or more.

  The amount of the surface treatment agent to be treated with the metal oxide fine particles is preferably 0.1 to 200 parts by mass, more preferably 7 to 70 parts by mass with respect to 100 parts by mass of the metal oxide fine particles before treatment. .

[Production of metal oxide fine particles having polymerizable unsaturated groups on the surface]
The following is an example of a method for producing fine metal oxide particles having a polymerizable unsaturated group on the surface, which has been surface-treated with a treatment agent having a radical polymerizable functional group, using tin oxide fine particles as metal oxide fine particles. I will explain.

  Tin oxide fine particles having a polymerizable unsaturated group on the surface can be obtained by subjecting the tin oxide fine particles to a surface treatment using a silane coupling agent having the radical polymerizable functional group (the exemplified compound). . When the surface treatment is performed, wet media using 0.1 to 200 parts by weight, more preferably 7 to 70 parts by weight, and 50 to 5000 parts by weight of the solvent as the silane coupling agent with respect to 100 parts by weight of the tin oxide fine particles before the treatment. It is preferred to process using a distributed device.

  Hereinafter, a surface treatment method for producing tin oxide fine particles that are surface-coated with a silane coupling agent having a radically polymerizable functional group that is more uniform and finer will be described.

  That is, by finely pulverizing tin oxide fine particles and simultaneously treating the surface of tin oxide fine particles by wet pulverizing a slurry (suspension of solid particles) containing tin oxide fine particles and a silane coupling agent having a radical polymerizable functional group. Progresses. Thereafter, since the solvent is removed to form powder, tin oxide fine particles that are surface-treated with a uniform and finer silane compound can be obtained.

  The wet media dispersion type apparatus which is a surface treatment apparatus used in the present invention is a metal oxide fine particle by filling beads in a container as a medium and rotating a stirring disk mounted perpendicularly to a rotation axis at high speed. The apparatus has a step of crushing, pulverizing and dispersing the aggregated particles of the metal oxide, and the constitution thereof should be a type in which the metal oxide fine particles are sufficiently dispersed and surface-treated when the surface treatment is performed on the metal oxide fine particles. For example, various types such as a vertical type, a horizontal type, a continuous type, and a batch type can be adopted. Specifically, a sand mill, ultra visco mill, pearl mill, glen mill, dyno mill, agitator mill, dynamic mill and the like can be used. These dispersive devices are pulverized and dispersed by impact crushing, friction, cutting, shear stress, etc., using a grinding medium such as balls and beads.

  As the beads used in the wet media dispersion type apparatus, balls made of glass, alumina, zircon, zirconia, steel, flint stone and the like can be used, and those made of zirconia or zircon are particularly preferable. Further, as the size of the beads, those having a diameter of about 1 to 2 mm are usually used, but in the present invention, those having a diameter of about 0.1 to 1.0 mm are preferably used.

  Various materials such as stainless steel, nylon and ceramic can be used for the disk and container inner wall used in the wet media dispersion type apparatus. In the present invention, the disk and container inner wall made of ceramic such as zirconia or silicon carbide are particularly used. Is preferred.

  By the wet treatment as described above, tin oxide fine particles surface-treated with the surface treatment agent can be obtained.

  As described above, tin oxide fine particles have been described. However, since metal oxide fine particles such as alumina, zinc oxide, titanium oxide, and silica also have a hydroxyl group on the surface in the same manner as tin oxide, a surface treatment agent as in tin oxide. It is possible to obtain metal oxide fine particles having a polymerizable unsaturated group that have been surface-treated with.

(Polymerizable compound)
Next, a polymerizable compound (a curable monomer having a polymerizable unsaturated group) that can be used in the present invention will be described.

  The polymerizable compound is preferably a monomer that is polymerized (cured) by irradiation with active rays such as ultraviolet rays and electron beams and becomes a resin generally used as a binder resin for a photoreceptor, such as polystyrene and polyacrylate. In particular, styrene monomers, acrylic monomers, methacrylic monomers, vinyl toluene monomers, vinyl acetate monomers, and N-vinyl pyrrolidone monomers are preferable.

Among these, radical polymerization having a polymerizable unsaturated group such as an acryloyl group (CH ₂ ═CHCO—) or a methacryloyl group (CH ₂ ═CCH ₃ CO—) is possible because it can be cured with a small amount of light or in a short time. Monomers or oligomers thereof are particularly preferred.

  In the present invention, the above polymerizable compounds may be used alone or in combination. In addition, these polymerizable compounds may use monomers, but may be used after oligomerization.

  Examples of these polymerizable compounds include, but are not limited to, the following compounds. Moreover, the polymerizable compound illustrated below is well-known and can be obtained as a commercial item.

  In the above formula, R represents the following acryloyl group, and R ′ represents the following methacryloyl group.

  Among the above, more preferable polymerizable compounds used in the present invention include M1, M2, and M3.

  The polymerizable compound is preferably a compound having 3 or more polymerizable unsaturated groups. In addition, two or more kinds of polymerizable compounds may be used in combination, but even in this case, it is preferable to use 50% by mass or more of the compound having 3 or more polymerizable unsaturated groups. The curable reactive group equivalent, that is, “curable functional group molecular weight / number of functional groups” is preferably 1000 or less, more preferably 500 or less. This increases the crosslink density and improves wear resistance.

  In the present invention, the protective layer is formed by curing reaction of the polymerizable compound. However, when reacting the polymerizable compound, a method of reacting by electron beam cleavage, a radical polymerization initiator is added, light, heat The method of reacting with is used. As the polymerization initiator, either a photopolymerization initiator or a thermal polymerization initiator can be used. Further, both light and heat initiators can be used in combination.

  Examples of the thermal polymerization initiator include 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethylazobisvaleronyl), 2,2′-azobis (2-methyl). Azo compounds such as butyronitrile); benzoyl peroxide (BPO), di-tert-butyl hydroperoxide, tert-butyl hydroperoxide, chlorobenzoyl peroxide, dichlorobenzoyl peroxide, bromomethylbenzoyl peroxide, lauroyl peroxide, etc. And peroxides.

  Examples of the photopolymerization initiator include diethoxyacetophenone, 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, 4- (2-hydroxyethoxy) phenyl- (2-hydroxy-2-propyl) ketone, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) butanone-1 (“Irgacure 369” manufactured by BASF Japan Ltd.), 2-hydroxy-2 -Methyl-1-phenylpropan-1-one, 2-methyl-2-morpholino (4-methylthiophenyl) propan-1-one, 1-phenyl-1,2-propanedione-2- (o-ethoxycarbonyl) Acetophenone or ketal photoinitiators such as oximes; benzoin, benzoin methyl ether Benzoin ether photopolymerization initiators such as benzoin ethyl ether, benzoin isobutyl ether, benzoin isopropyl ether; benzophenone, 4-hydroxybenzophenone, methyl o-benzoylbenzoate, 2-benzoylnaphthalene, 4-benzoylbiphenyl, 4-benzoyl Benzophenone photopolymerization initiators such as phenyl ether, acrylated benzophenone, 1,4-benzoylbenzene; 2-isopropylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2,4- Examples thereof include thioxanthone photopolymerization initiators such as dichlorothioxanthone.

  Examples of other photopolymerization initiators include ethyl anthraquinone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylethoxyphosphine oxide, and bis (2,4,6-trimethylbenzoyl). Phenylphosphine oxide (“Irgacure 819” manufactured by BASF Japan Ltd.), bis (2,4-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, methylphenylglyoxyester, 9,10-phenanthrene, acridine Compounds, triazine compounds, imidazole compounds and the like. In addition, a photopolymerization accelerator having a photopolymerization promoting effect can be used alone or in combination with the photopolymerization initiator. Examples of the photopolymerization accelerator include triethanolamine, methyldiethanolamine, ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, (2-dimethylamino) ethyl benzoate, and 4,4′-dimethylaminobenzophenone. Etc.

  As the radical polymerization initiator, a photopolymerization initiator is preferable, and an alkylphenone compound or a phosphine oxide compound is particularly preferable. In particular, a compound having an α-aminoalkylphenone structure or an acylphosphine oxide structure is preferable.

  These polymerization initiators may be used alone or in combination of two or more. Content of a polymerization initiator is 0.1-20 mass parts with respect to 100 mass parts of a polymeric compound, Preferably it is 0.5-10 mass parts.

[Compound of general formula (1)]
The photoreceptor according to the present invention contains a compound represented by the following general formula (1) in the protective layer.

In General Formula (1), R ₁ , R ₂ , R ₃ , and R ₄ each represent a hydrogen atom, an alkyl group having 1 to 7 carbon atoms, or an alkoxy group having 1 to 7 carbon atoms, and k, l , N represents an integer of 1 to 5, and m represents an integer of 1 to 4. Moreover, when these k, l, m, and n are plural, these plural groups may be the same or different.

  Examples of the alkyl group having 1 to 7 carbon atoms include methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, n-pentyl group, isopentyl group, neopentyl group, n- Hexyl group, 3-methylpentan-2-yl group, 3-methylpentan-3-yl group, 4-methylpentyl group, 4-methylpentan-2-yl group, 1,3-dimethylbutyl group, 3, 3-dimethylbutyl group, 3,3-dimethylbutan-2-yl group, n-heptyl group, 1-methylhexyl group, 3-methylhexyl group, 4-methylhexyl group, 5-methylhexyl group, 1-ethyl Pentyl group, 1- (n-propyl) butyl group, 1,1-dimethylpentyl group, 1,4-dimethylpentyl group, 1,1-diethylpropyl group, 1,3,3-trimethyl Methyl group, 1-ethyl-2,2-dimethylpropyl group and the like. Among these, a C1-C5 alkyl group is more preferable, and a methyl group, an ethyl group, a propyl group, n-butyl group, and n-pentyl group are still more preferable.

  Moreover, as a C1-C7 alkoxy group, a methoxy group, an ethoxy group n-propoxy group, an isopropoxy group, n-butoxy group, isobutoxy group, sec-butoxy group, tert-butoxy group, n-pentyloxy group , Isopentyloxy group, neopentyloxy group, 1,2-dimethyl-propoxy group, n-hexyloxy group, 3-methylpentan-2-yloxy group, 3-methylpentan-3-yloxy group, 4-methylpentyl Oxy group, 4-methylpentan-2-yloxy group, 1,3-dimethylbutyloxy group, 3,3-dimethylbutyloxy group, 3,3-dimethylbutan-2-yloxy group, n-heptyloxy group, 1 -Methylhexyloxy group, 3-methylhexyloxy group, 4-methylhexyloxy group, 5-methylhexylo Si group, 1-ethylpentyloxy group, 1- (n-propyl) butyloxy group, 1,1-dimethylpentyloxy group, 1,4-dimethylpentyloxy group, 1,1-diethylpropyloxy group, 1,3 , 3-trimethylbutyloxy group, 1-ethyl-2,2-dimethylpropyloxy group and the like. Among these, a C1-C2 alkoxy group is more preferable, and a methoxy group is further more preferable.

In particular, it is preferable that at least one of R ₁ , R ₂ , R ₃ , and R ₄ has a propyl group, a butyl group, or a pentyl group.

In particular, R ₁ and R ₂ are more preferably a hydrogen atom or a methyl group, respectively. More preferably, R ₃ is a hydrogen atom and R ₄ is an alkyl group having 1 to 5 carbon atoms. More preferably, k, l, m and n are each 1.

  The compound of the general formula (1) is an electron transporting compound that transports charge carriers in the protective layer, but does not exhibit absorption in a short wavelength region, and has a molecular weight of 450 or less (preferably 320 or more, 420 or less), and can enter the voids of the crosslinked cured resin layer of the protective layer. For this reason, it is possible to smoothly inject charge carriers from the charge transport layer without deteriorating the wear resistance of the protective layer, and the protective layer surface without causing an increase in residual potential or generation of transfer memory. Charge can be transported to

  Specific examples of the compound of the general formula (1) are shown below.

  The above compound can be synthesized by a known synthesis method, for example, a method described in JP-A-2006-143720.

[Fluorine resin fine particles]
The photoreceptor according to the present invention contains fluororesin fine particles in the protective layer.

  Examples of the fluorine resin constituting the fluorine resin fine particles include tetrafluoroethylene resin (PTFE), trifluoroethylene chloride resin, hexafluoroethylene chloride propylene resin, vinyl fluoride resin, vinylidene fluoride resin, difluoride. It is preferable to appropriately select one or two or more of the ethylene dichloride resin and copolymers thereof, and particularly preferred are ethylene tetrafluoride resin and vinylidene fluoride resin.

  Moreover, the average particle diameter of the fluorine resin fine particles is preferably 0.01 μm to 1 μm. Particularly preferably, it is 0.05 μm to 0.5 μm. If the average primary particle size of the fluororesin fine particles is larger than 0.01 μm, the particles are less likely to aggregate and the dispersibility can be improved. Further, when the average primary particle diameter of the fluororesin fine particles is 1 μm or less, a photoconductor having high light transmittance of the protective layer and excellent sensitivity characteristics can be obtained.

  The average primary particle size of the fluororesin fine particles was obtained by taking a magnified photograph of 10,000 times with a scanning electron microscope (manufactured by JEOL) and randomly taking 300 particles with a scanner (excluding aggregated particles). ) Automatic image processing analyzer LUZEX AP (Nireco Corporation) software version Ver. The value calculated from the average primary particle size using 1.32 is used.

  In addition, the molecular weight of the fluororesin constituting the fluororesin fine particles can be appropriately selected and is not particularly limited.

[Method for preparing protective layer]
The protective layer according to the present invention comprises a metal oxide fine particle having a polymerizable unsaturated group on the surface, a polymerizable compound, a compound represented by the general formula (1), a fluorine resin fine particle, a polymerization initiator, and the like. A coating solution for forming a protective layer mixed in a solvent is prepared, and the coating solution is applied onto a photosensitive layer to be described later, and then dried and cured to form a resin layer as a protective layer.

  In the process of coating, drying, and curing, the reaction between the polymerizable unsaturated groups of the metal oxide fine particles, the reaction between the polymerizable unsaturated group and the polymerizable compound, the reaction between the polymerizable compounds, and the like proceed. Then, a resin layer as a protective layer is formed. Here, the molecular weight of the resin forming the protective layer can be appropriately selected and is not particularly limited.

  The proportion of the metal oxide fine particles in the protective layer is preferably 20 to 170 parts by mass and more preferably 25 to 90 parts by mass when the resin component in the protective layer is 100 parts by mass. If the content of the metal oxide fine particles is 20 parts by mass or more with respect to 100 parts by mass of the resin component, the generation of image memory due to the increase in residual potential can be suppressed. Moreover, if it is 170 mass parts or less, favorable film quality will be obtained and a protective layer will become difficult to scrape. You may consider that the resin component in a protective layer is comprised when all the polymeric compounds contained in the coating liquid for protective layer formation carry out a curing reaction.

  The proportion of the compound of the general formula (1) in the protective layer is preferably 2 to 60 parts by mass of the compound of the general formula (1) when the resin component of the protective layer is 100 parts by mass. -50 mass parts is more preferable, and 10-35 mass parts is further more preferable. If it is 2 parts by mass or more, trapping of charge carriers in the protective layer is prevented, and the effect of preventing an increase in residual potential and occurrence of image memory (transfer memory) is high. Moreover, if it is 60 mass parts or less, favorable film quality will be obtained and a protective layer will become difficult to scrape.

  The ratio of the compound of the general formula (1) to the resin component in the protective layer is the content of the compound of the general formula (1) with respect to the content of the polymerizable compound in the coating solution for forming the protective layer. It may be considered similar to the ratio.

  The proportion of the fluorine-based resin fine particles in the protective layer is preferably 5 to 70 parts by mass, more preferably 10 to 60 parts by mass when the resin component in the protective layer is 100 parts by mass. When the proportion of the fluorine resin fine particles in the protective layer is 70 parts by mass or less with respect to 100 parts by mass of the resin component in the protective layer, the fluorine resin fine particles, the polymerizable compound, the metal oxide fine particles, the above formula (1) In a coating solution for forming a protective layer in which the above compound is dissolved or dispersed in a solvent, aggregation of the fluororesin fine particles is difficult to occur. Therefore, it is possible to prevent the resolution from being lowered by forming the protective layer while containing such agglomerated fluororesin fine particles. Further, since the strength of the protective layer can be prevented from decreasing due to the inclusion of aggregated fluororesin fine particles, a photoconductor with a small amount of wear and a long photoconductor life can be obtained. Further, if the proportion of the fluororesin fine particles in the protective layer is 5 parts by mass or more with respect to 100 parts by mass of the resin component in the protective layer, the coefficient of friction on the surface of the photoreceptor is sufficiently lowered, and the toner blade slips through. Can be reduced. Therefore, it is possible to prevent the charging roller from becoming dirty and the chargeability from deteriorating.

  Solvents for forming the protective layer include methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol, t-butanol, sec-butanol, benzyl alcohol, toluene, xylene, methylene chloride, methyl ethyl ketone, cyclohexane, acetic acid. Examples thereof include, but are not limited to, ethyl, butyl acetate, methyl cellosolve, ethyl cellosolve, tetrahydrofuran, 1-dioxane, 1,3-dioxolane, pyridine and diethylamine.

  Any solvent can be used as long as it can dissolve or disperse the polymerizable compound, the metal oxide fine particles having a polymerizable unsaturated group on the surface, the compound of the above formula (1), and the fluororesin fine particles. The method for producing the coating liquid is not particularly limited, and the polymerizable compound, the metal oxide fine particles having a polymerizable unsaturated group on the surface, the compound of the above formula (1), the fluorine resin fine particles, and various additives as required. May be added to the solvent and mixed with stirring until completely dissolved or dispersed. Further, the amount of the solvent is not particularly limited, and the solvent can be appropriately adjusted so that the coating solution has a viscosity suitable for the coating operation.

  The protective layer of the present invention is preferably subjected to a curing reaction by irradiation with actinic radiation after natural drying or heat drying after coating.

  As a coating method, known methods such as a dip coating method, a spray coating method, a spinner coating method, a bead coating method, a blade coating method, a beam coating method, a slide hopper method, and a circular slide hopper method can be used.

  The photoreceptor of the present invention is capable of generating a cured resin by irradiating actinic rays on the coating to generate radicals and polymerizing, and curing by forming a cross-linking bond between molecules and within the molecule. preferable. As the actinic radiation, ultraviolet rays and electron beams are more preferred, and ultraviolet rays are particularly preferred because they are easy to use.

As the ultraviolet light source, any light source that generates ultraviolet light can be used without limitation. For example, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a carbon arc lamp, a metal halide lamp, a xenon lamp, a flash (pulse) xenon, or the like can be used. Irradiation conditions vary depending on each lamp, but the irradiation amount of active rays is usually 5 to 500 mJ / cm ² , preferably 5 to 100 mJ / cm ² . The power of the lamp is preferably 0.1 kW to 5 kW, particularly preferably 0.5 kW to 3 kW.

  As an electron beam source, there is no particular limitation on the electron beam irradiation apparatus, and generally, an electron beam accelerator for electron beam irradiation is a curtain beam type that is relatively inexpensive and can provide a large output. Used. The acceleration voltage during electron beam irradiation is preferably 100 to 300 kV. The absorbed dose is preferably 0.5 to 10 Mrad.

  The irradiation time for obtaining the necessary irradiation amount of active rays is preferably 0.1 second to 10 minutes, and more preferably 0.1 second to 5 minutes from the viewpoint of work efficiency.

  In the present invention, drying can be performed before and after irradiation with active rays and during irradiation with active rays, and the timing of drying can be appropriately selected by combining them.

  Drying conditions can be appropriately selected depending on the type of solvent, film thickness, and the like. The drying temperature is preferably room temperature to 180 ° C, particularly preferably 80 ° C to 140 ° C. The drying time is preferably 1 minute to 200 minutes, and particularly preferably 5 minutes to 100 minutes.

The thickness of the protective layer is preferably 0.2 to 10 μm, more preferably 0.5 to 6 μm.

[Configuration of electrophotographic photoreceptor]
The configuration of the electrophotographic photosensitive member other than the protective layer is described below.

  The photoconductor of the present invention is preferably an organic photoconductor constituted by giving an organic compound at least one of a charge generation function and a charge transport function indispensable for the construction of an electrophotographic photoconductor. The organic photoreceptor contains all known organic photoreceptors such as a photoreceptor composed of a known organic charge generating material or an organic charge transporting material, a photoreceptor composed of a polymer complex with a charge generating function and a charge transporting function. To do.

  The photoreceptor of the present invention preferably has a layer structure in which a charge generation layer, a charge transport layer, and a protective layer are sequentially laminated as a photosensitive layer on a conductive support. In addition, an intermediate layer is preferably provided between the conductive support and the charge generation layer.

  The layer structure of the electrophotographic photosensitive member of the present invention will be described focusing on the above.

(Conductive support)
The support used in the present invention may be any one as long as it has conductivity, for example, a metal such as aluminum, copper, chromium, nickel, zinc and stainless steel formed into a drum or a sheet, aluminum or copper Metal foils such as those laminated on plastic films, aluminum, indium oxide and tin oxide deposited on plastic films, metals with conductive layers applied alone or with a binder resin, plastic films and For example, paper.

(Middle layer)
In the present invention, an intermediate layer having a barrier function and an adhesive function can be provided between the conductive support and the photosensitive layer. Considering various types of failure prevention, it can be said that providing an intermediate layer is a preferable mode.

  The intermediate layer can be formed by dissolving a binder resin such as casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, polyamide, polyurethane and gelatin in a known solvent, and applying the same coating method as the protective layer, such as dip coating. Of these, an alcohol-soluble polyamide resin is preferred.

  In addition, inorganic particles such as various conductive fine particles and metal oxide particles can be contained for the purpose of adjusting the resistance of the intermediate layer. For example, various metal oxide particles such as alumina, zinc oxide, titanium oxide, tin oxide, antimony oxide, indium oxide, bismuth oxide, ultrafine particles such as indium oxide doped with tin, tin oxide doped with antimony, and zirconium oxide. Can be used.

  These inorganic particles may be used alone or in combination. When two or more types are mixed, it may take the form of a solid solution or fusion. The average particle size of such inorganic particles is preferably 0.3 μm or less, more preferably 0.1 μm or less.

  As the solvent used for forming the intermediate layer, a solvent in which inorganic particles are well dispersed and a binder resin, particularly a polyamide resin, is dissolved is preferable. Specifically, alcohols having 1 to 4 carbon atoms such as methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol, t-butanol and sec-butanol are excellent in solubility and coating performance of polyamide resin. preferable. Further, in order to improve the storage stability and the dispersibility of the particles, a co-solvent that can be used in combination with the above-mentioned solvent and can obtain a preferable effect may be further used, and examples thereof include benzyl alcohol, toluene, methylene chloride, cyclohexanone, and tetrahydrofuran. .

  In the coating solution for forming the intermediate layer, the concentration of the binder resin can be appropriately selected according to the thickness of the intermediate layer and the production rate.

  The mixing ratio of the inorganic particles to the binder resin when the inorganic particles are dispersed is preferably 20 to 400 parts by mass, more preferably 50 to 350 parts by mass with respect to 100 parts by mass of the binder resin.

  As a means for dispersing the inorganic particles, an ultrasonic disperser, a ball mill, a sand mill, a homomixer, or the like can be used, but it is not limited to these.

  In order to form the intermediate layer, the binder resin is dissolved in the above solvent, and the inorganic fine particles are dispersed by the above method, and then this solution can be applied on the conductive support to a desired thickness. . Thereafter, the applied layer is dried to complete the intermediate layer. The method for drying the intermediate layer can be appropriately selected according to the type of solvent and the film thickness, but thermal drying is preferred.

  The thickness of the intermediate layer is preferably from 0.1 to 15 μm, more preferably from 0.3 to 10 μm.

(Charge generation layer)
The charge generation layer used in the photoreceptor of the present invention preferably contains a charge generation material and a binder resin, and is preferably formed by dispersing and coating the charge generation material in a binder resin solution.

  Charge generation materials include azo raw materials such as Sudan Red and Diane Blue, quinone pigments such as pyrenequinone and anthanthrone, quinocyanine pigments, perylene pigments, indigo pigments such as indigo and thioindigo, and polycyclic quinone pigments such as pyranthrone and diphthaloylpyrene. And phthalocyanine pigments, but are not limited thereto. Preferred are polycyclic quinone pigments and titanyl phthalocyanine pigments. These charge generating substances can be used alone or in a form dispersed in a known resin.

  As the binder resin of the charge generation layer, a known resin can be used, for example, polystyrene resin, polyethylene resin, polypropylene resin, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, polyvinyl butyral resin, epoxy resin, Polyurethane resins, phenol resins, polyester resins, alkyd resins, polycarbonate resins, silicone resins, melamine resins, and copolymer resins containing two or more of these resins (eg, vinyl chloride-vinyl acetate copolymer resins, chlorides) Vinyl-vinyl acetate-maleic anhydride copolymer resin) and poly-vinylcarbazole resin, but are not limited thereto. Polyvinyl butyral resin is preferable.

  The charge generation layer is formed by dispersing a charge generation material in a solution in which a binder resin is dissolved in a solvent using a disperser to prepare a coating solution, and applying the coating solution to a certain film thickness using a coating device. It is preferable to prepare the film by drying. As a coating method, the same method as that of the protective layer can be used.

  Solvents for dissolving and coating the binder resin used in the charge generation layer include, for example, toluene, xylene, methylene chloride, 1,2-dichloroethane, methyl ethyl ketone, cyclohexane, ethyl acetate, t-butyl acetate, methanol, ethanol, Examples include, but are not limited to, propanol, butanol, methyl cellosolve, 4-methoxy-4-methyl-2-pentanone, ethyl cellosolve, tetrahydrofuran, 1-dioxane, 1,3-dioxolane, pyridine, and diethylamine. Absent.

  As a means for dispersing the charge generating substance, an ultrasonic disperser, a ball mill, a sand mill, a homomixer, or the like can be used, but is not limited thereto.

  The mixing ratio of the charge generating material to the binder resin is preferably 1 to 600 parts by mass, more preferably 50 to 500 parts by mass with respect to 100 parts by mass of the binder resin. The thickness of the charge generation layer varies depending on the characteristics of the charge generation material, the characteristics of the binder resin, the mixing ratio, and the like, but is preferably 0.01 to 5 μm, more preferably 0.05 to 3 μm. It should be noted that the coating solution for the charge generation layer can prevent the occurrence of image defects by filtering foreign matter and aggregates before coating. It can also be formed by vacuum deposition of the pigment.

(Charge transport layer)
The charge transport layer used in the photoreceptor of the present invention preferably contains a charge transport material (CTM) and a binder resin, and is formed by dissolving and coating the charge transport material in a binder resin solution. Is preferred.

  Examples of the charge transport material for the charge transport layer include a triphenylamine derivative, a hydrazone compound, a styryl compound, a benzidine compound, and a butadiene compound as a material that transports charges (holes).

  A known resin can be used as the binder resin for the charge transport layer, and polycarbonate resin, polyacrylate resin, polyester resin, polystyrene resin, styrene-acrylonitrile copolymer resin, polymethacrylic ester resin, and styrene-methacrylic acid. Examples include ester copolymer resins, and polycarbonate is preferred. Furthermore, bisphenol A (BPA), bisphenol Z (BPZ), dimethyl BPA, BPA-dimethyl BPA copolymer and the like are preferable in terms of crack resistance, wear resistance, and charging characteristics.

  The charge transport layer is preferably formed by dissolving the binder resin and the charge transport material to prepare a coating solution, applying the coating solution to a certain film thickness with a coating machine, and drying the coating film. As a coating method, the same method as that of the protective layer can be used.

  Examples of the solvent for dissolving the binder resin and the charge transporting substance include toluene, xylene, methylene chloride, 1,2-dichloroethane, methyl ethyl ketone, cyclohexanone, ethyl acetate, butyl acetate, methanol, ethanol, propanol, butanol, Examples thereof include, but are not limited to, tetrahydrofuran, 1,4-dioxane, 1,3-dioxolane, pyridine, and diethylamine.

  The mixing ratio of the charge transporting material to the binder resin is preferably 10 to 500 parts by weight, more preferably 20 to 250 parts by weight with respect to 100 parts by weight of the binder resin.

  The thickness of the charge transport layer varies depending on the characteristics of the charge transport material, the characteristics of the binder resin, the mixing ratio, and the like, but is preferably 5 to 40 μm, and more preferably 10 to 30 μm.

  An antioxidant, an electronic conductive agent, a stabilizer, silicone oil, or the like may be added to the charge transport layer. As the antioxidant, those described in JP-A No. 2000-305291 and as the electronic conductive agent are described in JP-A Nos. 50-137543 and 58-76483.

[Image forming apparatus]
The above-described electrophotographic photosensitive member of the present invention is used by being mounted on an image forming apparatus, and can form a high-quality image. Therefore, the present invention also provides an image forming apparatus equipped with the electrophotographic photosensitive member of the present invention.

  The image forming apparatus of the present invention is preferably a photoconductor of the present invention, a charging unit for charging the surface of the photoconductor, an exposure unit for exposing the charged photoconductor to form an electrostatic latent image, on the photoconductor The latent image is developed with toner to form a toner image and a cleaning unit.

  As the charging unit, a contact charging type charging unit is preferably used. By using the contact charging type charging means, the effects of the present invention can be obtained more remarkably.

  The contact charging type charging unit is disposed in contact with the photosensitive member, and charges the photosensitive member to a desired polarity and potential by applying a voltage of, for example, about −2.5 to −1.5 kV to the charging unit. Such a contact charging type charging means is not particularly limited, and known means such as a charging roller, a charging brush, a charging belt, and a charging blade can be used. Among these, it is preferable to use a charging roller from the viewpoint of charging stability.

  As a voltage applied to the charging means, a DC charging method in which only a direct current electric field is applied to charge the photosensitive member, and an AC in which an alternating electric field is superimposed on the direct current electric field is applied to the charging member to charge the photosensitive member. Any of the charging methods can be used, but the AC charging method that provides a smoothing effect by an AC electric field is preferable because of excellent charging uniformity.

  In the AC charging method, as the voltage applied to the charging means, a DC electric field or an AC electric field can be selected from DC constant voltage, DC constant current, AC constant voltage, and AC constant current.

  Hereinafter, an image forming apparatus according to the present invention will be described with reference to the drawings.

  FIG. 1 schematically shows an example of the configuration of an image forming apparatus according to the present invention.

  An image forming apparatus 10 shown in FIG. 1 includes a drum-type photoreceptor 1 as an image carrier. Around the photoreceptor 1, a charging unit (charging roller) 2, an exposure unit 3, a developing unit 4, a transfer unit (transfer roller) 5 and a cleaning unit 6 are arranged in this order. A cleaning device 80 is provided for the charging means 2.

  In FIG. 1, a fixing device 700 is disposed on the left side of the transfer roller 5. In this example, the fixing device 700 includes a fixing roller 710 incorporating a heat source such as a heater lamp and a pressure roller 720 facing the fixing roller 710.

  According to this image forming apparatus 10, the photosensitive member 1 is rotated clockwise in the figure by a photosensitive member driving motor (not shown), and the surface thereof is uniformly charged to a predetermined potential by the charging roller 2. At this time, a charging voltage is applied to the charging roller 2 from a charging power supply (not shown). The charging roller 2 may contact the surface of the photosensitive member 1 and rotate counterclockwise. In this example, the charging roller 2 contacts the photosensitive member 1 and rotates counterclockwise. It is designed to be rotated by a drive unit.

  In this way, image exposure corresponding to the image to be formed from the exposure unit 3 is performed on the photosensitive member charging area charged to a predetermined potential, and an electrostatic latent image is formed on the photosensitive member 1. The electrostatic latent image is developed by the developing roller 41 of the developing unit 4 to which a developing bias is applied from a power supply (not shown) to become a visible toner image.

  Note that image exposure by the exposure means 3 is performed based on image information supplied from a scanner, a computer, etc. (not shown).

  On the other hand, a transfer material (recording medium) S is supplied from a transfer material supply unit such as a recording paper (not shown), and is temporarily held by a timing roller pair (not shown). When the toner image on the photoconductor 1 arrives between the photoconductor 1 and the transfer roller 5, the image forming target area of the transfer material S is just between the photoconductor 1 and the transfer roller 5. The toner image on the photoconductor 1 is transferred onto the transfer material S by the transfer roller 5 that is fed between the photoconductor 1 and the transfer roller 5 so as to arrive and to which a transfer voltage is applied from a transfer power supply (not shown).

  The transfer material S onto which the toner image has been transferred in this manner passes through the fixing device 700, whereby the transferred toner image is fixed under heat and pressure, and then discharged onto a recording medium discharge tray (not shown).

  In this example of the cleaning means 6, the transfer residual toner remaining on the photoreceptor 1 is removed and cleaned by the cleaning blade 61, and the removed transfer residual toner is stored in the storage unit 62.

Here, as the cleaning blade 61 used in the present embodiment, for example, one formed of an elastic material made of polyurethane rubber can be used. The contact pressure of the cleaning blade 61 with respect to the photoreceptor 1 is preferably set to about 1.96 to 5.88 × 10 ⁻² N / mm (2.0 to 6.0 gf / mm).

(toner)
The toner used in the present exemplary embodiment is not particularly limited, but a toner having a shape factor SF of less than 140 with a true sphere of 100 is preferably used. If the shape factor SF is less than 140, good transferability and the like can be obtained, and the image quality of the obtained image can be improved. On the other hand, the toner particles preferably have a volume average particle diameter of 2 to 8 μm from the viewpoint of achieving high image quality.

  The toner particles usually contain a binder resin and a colorant, and optionally contain a release agent. The binder resin, colorant, and release agent can be any material that has been used in conventional toners, and is not particularly limited.

  The method for obtaining the toner particles is not particularly limited, but for example, a normal pulverization method, a wet melt spheronization method prepared in a dispersion medium, suspension polymerization, dispersion polymerization, emulsion polymerization aggregation method For example, a toner production method using a known polymerization method can be used.

  Further, as external additives, inorganic fine particles such as silica and titania having an average particle diameter of about 10 to 300 nm and an abrasive of about 0.2 to 3 μm are appropriately added as external additives, and an average particle diameter of 25 to 45 μm is added. The developer can be obtained by mixing with a carrier made of ferrite beads or the like.

  FIG. 2 is a cross-sectional configuration diagram of a color image forming apparatus showing an embodiment of the present invention.

  This color image forming apparatus is called a tandem type color image forming apparatus, and includes four sets of image forming units (image forming units) 10Y, 10M, 10C, and 10Bk, an endless belt-shaped intermediate transfer body unit 7, and a feeding unit. It comprises a paper conveying means 21 and a fixing means 24. A document image reading device SC is disposed on the upper part of the main body A of the image forming apparatus.

  The image forming unit 10Y that forms a yellow image includes a charging unit (charging step) 2Y of a charging roller disposed in contact with the periphery of a drum-shaped photoconductor 1Y serving as a first image carrier, and an exposure unit ( Exposure process) 3Y, developing means (developing process) 4Y, primary transfer roller 5Y as primary transfer means (primary transfer process), and cleaning means 6Y. An image forming unit 10M that forms a magenta image includes a drum-shaped photosensitive member 1M as a first image carrier, a charging unit 2M, an exposure unit 3M, a developing unit 4M, a primary transfer roller 5M as a primary transfer unit, It has a cleaning means 6M. An image forming unit 10C for forming a cyan image includes a drum-shaped photoreceptor 1C as a first image carrier, a charging unit 2C, an exposure unit 3C, a developing unit 4C, and a primary transfer roller 5C as a primary transfer unit. It has cleaning means 6C. The image forming unit 10Bk that forms a black image includes a drum-shaped photoreceptor 1Bk as a first image carrier, a charging unit 2Bk, an exposure unit 3Bk, a developing unit 4Bk, a primary transfer roller 5Bk as a primary transfer unit, and a cleaning unit. 6Bk.

  The four sets of image forming units 10Y, 10M, 10C, and 10Bk include charging means 2Y, 2M, 2C, and 2Bk that rotate around the photosensitive drums 1Y, 1M, 1C, and 1Bk, and exposure means 3Y, 3M, and 3C. 3Bk, rotating developing means 4Y, 4M, 4C and 4Bk, and cleaning means 6Y, 6M, 6C and 6Bk for cleaning the photosensitive drums 1Y, 1M, 1C and 1Bk.

  The image forming units 10Y, 10M, 10C, and 10Bk have the same configuration except that the colors of toner images formed on the photoreceptors 1Y, 1M, 1C, and 1Bk are different, and the image forming unit 10Y is taken as an example in detail. explain.

  The image forming unit 10Y has a charging unit 2Y (hereinafter simply referred to as a charging unit 2Y or a charger 2Y), an exposure unit 3Y, a developing unit 4Y, and a cleaning unit 6Y (around a photosensitive drum 1Y as an image forming body). Hereinafter, the cleaning unit 6Y or the cleaning blade 6Y) is simply disposed, and a yellow (Y) toner image is formed on the photosensitive drum 1Y. In the present embodiment, in the image forming unit 10Y, at least the photosensitive drum 1Y, the charging unit 2Y, the developing unit 4Y, and the cleaning unit 6Y are provided so as to be integrated.

  The charging means 2Y is a means for applying a uniform potential to the photosensitive drum 1Y. In the present embodiment, a charging roller type charger 2Y is used for the photosensitive drum 1Y.

  The exposure means 3Y performs exposure based on the image signal (yellow) on the photosensitive drum 1Y given a uniform potential by the charger 2Y, and forms an electrostatic latent image corresponding to the yellow image. The exposure means 3Y is composed of an LED in which light emitting elements are arrayed in the axial direction of the photosensitive drum 1Y and an imaging element (trade name; Selfoc lens), or a laser. An optical system or the like is used.

  The image forming apparatus of the present invention is configured by integrally combining the above-described photosensitive member and components such as a developing device and a cleaning device as a process cartridge (image forming unit), and this image forming unit is connected to the apparatus main body. It may be configured to be detachable. In addition, at least one of a charging device, an image exposure device, a developing device, a transfer or separation device, and a cleaning device is integrally supported together with a photosensitive member to form a process cartridge (image forming unit), which is detachable from the apparatus main body. A single image forming unit may be detachable using guide means such as a rail of the apparatus main body.

  The endless belt-like intermediate transfer body unit 7 includes an endless belt-like intermediate transfer body 70 as a second image carrier having a semiconductive endless belt shape that is wound around a plurality of rollers and is rotatably supported.

  Each color image formed by the image forming units 10Y, 10M, 10C, and 10Bk is sequentially transferred onto a rotating endless belt-shaped intermediate transfer body 70 by primary transfer rollers 5Y, 5M, 5C, and 5Bk as primary transfer means. Thus, a synthesized color image is formed. A transfer material P as a transfer material (a support for carrying a fixed final image: for example, plain paper, a transparent sheet, etc.) housed in the paper feed cassette 20 is fed by a paper feed means 21 and a plurality of intermediates. After passing through rollers 22A, 22B, 22C, 22D and registration roller 23, they are conveyed to a secondary transfer roller 5b as a secondary transfer means, and are secondarily transferred onto a transfer material P to transfer a color image all at once. The transfer material P onto which the color image has been transferred is subjected to fixing processing by the fixing unit 24, is sandwiched between paper discharge rollers 25, and is placed on a paper discharge tray 26 outside the apparatus. Here, a toner image transfer support formed on a photosensitive member such as an intermediate transfer member or a transfer material is collectively referred to as a transfer medium.

  On the other hand, after the color image is transferred to the transfer material P by the secondary transfer roller 5b as the secondary transfer means, the residual toner is removed by the cleaning means 6b from the endless belt-shaped intermediate transfer body 70 in which the transfer material P is separated by curvature. The

  During the image forming process, the primary transfer roller 5Bk is always in contact with the photoreceptor 1Bk. The other primary transfer rollers 5Y, 5M, and 5C are in contact with the corresponding photoreceptors 1Y, 1M, and 1C, respectively, only during color image formation.

  The secondary transfer roller 5b contacts the endless belt-shaped intermediate transfer body 70 only when the transfer material P passes through the secondary transfer roller 5b.

  Further, the housing 8 can be pulled out from the apparatus main body A through the support rails 82L and 82R.

  The housing 8 includes image forming units 10Y, 10M, 10C, and 10Bk and an endless belt-shaped intermediate transfer body unit 7.

  The image forming units 10Y, 10M, 10C, and 10Bk are arranged in tandem in the vertical direction. An endless belt-shaped intermediate transfer body unit 7 is disposed on the left side of the photoreceptors 1Y, 1M, 1C, and 1Bk in the drawing. The endless belt-shaped intermediate transfer body unit 7 includes an endless belt-shaped intermediate transfer body 70 that can be rotated by winding rollers 71, 72, 73, 74, primary transfer rollers 5Y, 5M, 5C, 5Bk, and cleaning means 6b. Consists of.

  The present invention also provides an image forming method for forming an electrophotographic image using the above image forming apparatus. According to the image forming method of the present invention, a good electrophotographic image can be formed stably over a long period of time.

  Hereinafter, the present invention will be specifically described through examples and comparative examples. However, the present invention is not limited to these examples. In the following text, “part” means “part by mass”.

Example 1
(Preparation of photoreceptor 1)
Photoreceptor 1 was produced as follows.

  The surface of a cylindrical aluminum support having a diameter of 60 mm was cut to prepare a conductive support having a fine and rough surface.

<Intermediate layer>
A dispersion having the following composition was diluted twice with the same solvent, allowed to stand overnight, and then filtered (filter; using a lysh mesh 5 μm filter manufactured by Nihon Pall) to prepare an intermediate layer coating solution.

Polyamide resin CM8000 (manufactured by Toray Industries, Inc.) 1 part Titanium oxide SMT500SAS (manufactured by Teika) 3 parts Methanol 10 parts Dispersion was carried out for 10 hours in a batch manner using a sand mill as a disperser.

  It apply | coated by the dip coating method so that it might become a dry film thickness of 2 micrometers on the said support body using the said coating liquid.

<Charge generation layer>
Charge generation material: Pigment (CG-1) below: 20 parts Polyvinyl butyral resin (# 6000-C: manufactured by Denki Kagaku Kogyo Co., Ltd.) 10 parts t-butyl acetate 700 parts 4-methoxy-4-methyl-2-pentanone 300 parts The above components were mixed and dispersed for 10 hours using a sand mill to prepare a charge generation layer coating solution. This coating solution was applied onto the intermediate layer by a dip coating method to form a charge generation layer having a dry film thickness of 0.3 μm.

(Synthesis of Pigment (CG-1))
(1) Synthesis of amorphous titanyl phthalocyanine 29.2 parts by mass of 1,3-diiminoisoindoline is dispersed in 200 parts by mass of o-dichlorobenzene, and nitrogen atmosphere is added by adding 20.4 parts by mass of titanium tetra-n-butoxide. Under heating at 150 to 160 ° C. for 5 hours. After allowing to cool, the precipitated crystals were filtered, washed with chloroform, 2% aqueous hydrochloric acid, water and methanol, and dried to obtain 26.2 parts by mass (yield 91%) of crude titanyl phthalocyanine.

  Subsequently, the obtained crude titanyl phthalocyanine was dissolved by stirring for 1 hour in 250 parts by mass of concentrated sulfuric acid at 5 ° C. or less, and poured into 5000 parts by mass of water at 20 ° C. The precipitated crystals were filtered and sufficiently washed with water to obtain 225 parts by mass of a wet paste product.

  The obtained wet paste product was frozen in a freezer, thawed again, filtered and dried to obtain 24.8 parts by mass of amorphous titanyl phthalocyanine (yield 86%).

(2) Synthesis of (2R, 3R) -2,3-butanediol adduct titanyl phthalocyanine (CG-1) 10.0 parts by mass of the above-mentioned amorphous titanyl phthalocyanine and (2R, 3R) -2,3-butane Diol 0.94 part by mass (0.6 equivalent ratio) (equivalent ratio is equivalent ratio to amorphous titanyl phthalocyanine, hereinafter the same) was mixed in 200 parts by mass of o-dichlorobenzene (ODB), and 60-70 ° C. And stirred for 6 hours. After leaving overnight, methanol was added to the reaction solution, and the resulting crystals were filtered. The filtered crystals were washed with methanol, and a pigment containing (2R, 3R) -2,3-butanediol adduct titanyl phthalocyanine CG-1 10.3 mass parts was obtained. In the X-ray diffraction spectrum of CG-1, there are clear peaks at 8.3 °, 24.7 °, 25.1 °, and 26.5 °. In the mass spectrum, there is a peak in the 576 and 648, both the absorption of O-Ti-O appears Ti = O near 970 cm ^-1, around 630 cm ^-1 in the IR spectrum. Further, in thermal analysis (TG), there is a mass loss of about 7% at 390 to 410 ° C., so that a 1: 1 adduct and a non-adduct of titanyl phthalocyanine and (2R, 3R) -2,3-butanediol Presumed to be a mixture with titanyl phthalocyanine (not added).

<Charge transport layer>
Charge transporting substance (compound A below) 225 parts Binder: Polycarbonate Z (Z300: manufactured by Mitsubishi Gas Chemical Company) 300 parts Antioxidant (Irganox 1010: manufactured by BASF Japan) 6 parts THF (tetrahydrofuran) 1600 parts Toluene 400 parts Silicone oil (KF-50: manufactured by Shin-Etsu Chemical Co., Ltd.) 1 part was mixed and dissolved to prepare a charge transport layer coating solution.

  This coating solution was applied onto the charge generation layer using a circular slide hopper coating machine to form a charge transport layer having a dry film thickness of 20 μm.

<Protective layer>
Surface treatment with a compound having a radical polymerizable functional group as shown below using tin oxide having the following characteristics as the metal oxide fine particles, using the exemplified compound (S-15) as the compound having a radical polymerizable functional group Went.

  First, a mixed solution of 100 parts of tin oxide, 30 parts of the exemplary compound (S-15), and 300 parts of a mixed solvent of toluene / isopropyl alcohol = 1/1 (mass ratio) is put in a sand mill together with zirconia beads at about 40 ° C. The mixture was stirred at a rotational speed of 1500 rpm and subjected to surface treatment with a compound having a radically polymerizable functional group of tin oxide fine particles. Further, the above treatment mixture is taken out, put into a Henschel mixer, stirred for 15 minutes at a rotation speed of 1500 rpm, and then dried at 120 ° C. for 3 hours, whereby the surface treatment of the tin oxide fine particles with the compound having a radical polymerizable functional group is performed. When finished, surface-treated tin oxide fine particles were obtained. By the surface treatment with the compound having the radical polymerizable functional group, the particle surface of the tin oxide fine particles is coated with the compound of Exemplified Compound S-15. The X-ray fluorescence analyzer “XRF-1700 (manufactured by Shimadzu Corporation)” This was confirmed by detecting the Si peak.

  The tin oxide used was tin oxide having the following characteristics manufactured by CIK Nanotech.

Number average primary particle size: 20 nm, volume resistivity: 1.05 × 10 ⁵ (Ω · cm)
Subsequently, a protective layer was formed by the following method.

  100 parts by mass of a polymerizable compound (Exemplary Compound M1) and 15 parts by mass of a charge transporting substance (Exemplary Compound CTM-8), 510 parts by mass of 1-propanol, 50 parts by mass of tetrahydrofuran (THF), and 240 parts by mass of methyl isobutyl ketone Part of the solvent mixture. Further, 60 parts by mass of fluorine resin fine particles (average primary particle size 300 nm, KTL500F: manufactured by Kitamura Co., Ltd.) and 60 parts by mass of surface-treated tin oxide fine particles (surface-treated with S-15) were added, and 15 with an ultrasonic homogenizer. Dispersion was performed for a minute to obtain a dispersion containing a polymerizable compound, a charge transporting substance, fluorine resin fine particles, and surface-treated tin oxide fine particles. 15 parts by mass of a polymerization initiator (Irgacure 819 manufactured by BASF Japan) was added to the dispersion to prepare a coating solution for forming a protective layer.

  A surface layer was applied using a circular slide hopper applicator on the photoreceptor in which the coating liquid for forming the protective layer was previously prepared up to the charge transport layer. After the coating, the photosensitive member 1 was produced by irradiating with an ultraviolet ray for 1 minute using a metal halide lamp to form a protective layer having a dry film thickness of 3.0 μm.

(Examples 2 to 6)
(Preparation of photoconductors 2 to 6)
In the production of the photoreceptor 1, the compounds of the general formula (1) (charge transporting substance), surface-treated metal oxide fine particles, polymerizable compounds, fluororesin fine particles, etc. of the protective layer are shown in Tables 1 and 2 below. Photoconductors 2 to 6 were produced in the same manner except that the photosensitive members 2 to 6 were changed.

(Comparative Example 1)
(Preparation of photoconductor 7)
Photoreceptor 7 was produced in the same manner except that fluororesin fine particles were not used in the production of photoreceptor 1.

(Comparative Example 2)
(Preparation of photoconductor 8)
Photoreceptor 8 was produced in the same manner as in production of photoconductor 1, except that the charge transport material of the protective layer was changed from CTM-8 to a comparative charge transport material (comparative CTM) represented by the following chemical formula.

(Comparative Example 3)
(Preparation of photoconductor 9)
Photoconductor 9 was prepared in the same manner except that no charge transporting substance was used in the production of photoconductor 1.

(Comparative Example 4)
(Preparation of photoconductor 10)
In production of the photoreceptor 1, tin oxide fine particles were replaced with methyl hydrogen polysiloxane (KF-99, manufactured by Shin-Etsu Chemical Co., Ltd.), which is a surface treatment agent having no polymerizable unsaturated group, instead of the exemplified compound S-15. A photoconductor 10 was produced in the same manner except that the surface treatment was performed.

  The metal oxide fine particles used in each example and comparative example are as follows.

(Evaluation)
As an evaluation machine, a modified machine in which the charger of bizhub C360 manufactured by Konica Minolta Business Technologies, Inc. was replaced with a charging roller was used.

  In a 23 ° C./50% RH environment, an endurance test was performed in which a character image with an image ratio of 6% was printed on both sides of 300,000 sheets continuously by A4 horizontal feed. After the durability test, the chargeability, surface roughness, coefficient of friction, and image memory of the photoreceptor were evaluated.

(Chargeability)
When the photoconductor is placed in the drum cartridge of the evaluator and the surface potential Vs of the photoconductor is measured and plotted while changing the amplitude Vpp (peak-to-peak value) of the AC component of the AC voltage applied to the charging roller, the surface potential Vs is plotted. Vpp at which V is constant was defined as Vknee. By measuring Vknee (V), the chargeability can be evaluated, and it can be said that the smaller the value of Vknee (V), the better the chargeability. Table 2 below shows the value of Vknee (V) measured for the photoconductors produced in the respective examples and comparative examples. If the value of Vknee (V) is less than 1400V, it is considered that there is no practical problem.

(Surface roughness)
The average roughness Ra (μm) was measured according to JISB0601: 2001. The following conditions were used as measurement conditions.

Measuring machine: Surface roughness meter (Surfcom 1400D manufactured by Tokyo Seimitsu Co., Ltd.)
Measurement length L: 4.0 mm
Cut-off wavelength λc: 0.08 mm
Stylus tip shape: cone with a tip angle of 60 ° Stylus tip radius: 0.5 μm
Measurement speed: 0.3 mm / sec
Measurement magnification: 100,000 times Measurement position: Center of the center of the cylindrical photoconductor and the middle point between the shaft center and the end (total friction coefficient)
A portable friction meter (Muse TYPE: 94i-II manufactured by HEIDON) was vertically applied to the sample, and the coefficient of static friction was measured.

(Evaluation of image memory)
After the endurance test, 10 sheets of solid black and solid white mixed images are printed continuously, and then a uniform halftone image is printed. The solid black and solid white history appears in the halftone image. Judgment is based on whether (memory is generated) or not (memory is not generated).

○: No memory generated ×: Memory generated Evaluation results are summarized in Table 2.

  From the results of Table 2 above, a composition obtained by reacting metal oxide fine particles having a polymerizable unsaturated group on the surface and a polymerizable compound having the configuration of the present invention, and a fluororesin The photoreceptor (photoreceptor Nos. 1 to 6) containing the fine particles and the charge transporting substance represented by the general formula (1) has obtained good evaluation in each evaluation item.

  On the other hand, in the photoreceptor 7 in which the protective layer does not contain fluorine resin fine particles, sufficient characteristics in chargeability and friction coefficient were not obtained. Also, good chargeability could not be obtained with the photoconductor 8 that does not contain a specific charge transport material, and image memory was generated with the photoconductor 9 that did not use a charge transport material. Furthermore, in the photoreceptor 10 in which the metal oxide fine particles do not have a polymerizable unsaturated group on the surface, sufficient characteristics in chargeability and friction coefficient were not obtained.

  Therefore, it has been clarified that by using the photoconductor of the present invention, the charging property of the charging roller is improved and the coefficient of friction on the surface of the photoconductor is reduced.

1, 1Y, 1M, 1C, 1Bk photoconductor 2, 2Y, 2M, 2C, 2Bk charging unit 3, 3Y, 3M, 3C, 3Bk exposure unit 4, 4Y, 4M, 4C, 4Bk developing unit 5 transfer unit 5Y, 5M 5C, 5Bk Primary transfer means 5b Secondary transfer roller 6, 6Y, 6M, 6C, 6Bk, 6b Cleaning means 7 Intermediate transfer body unit 8 Case 10 Image forming apparatus 10Y, 10M, 10C, 10Bk Image forming unit 20 Paper feed Cassette 21 Paper feed means (paper feed means)
22A, 22B, 22C, 22D Intermediate roller 23 Registration roller 24 Fixing means 25 Paper discharge roller 26 Paper discharge tray 41 Developing roller 61 Cleaning blade 62 Storage section 70 Intermediate transfer member 71, 72, 73, 74 Roller 80 Cleaning device 82L, 82R Support rail 700 Fixing device 710 Fixing roller 720 Pressure roller A Image forming device S, P Transfer material (recording medium)
SC document image reading device

Claims (5)

In an electrophotographic photosensitive member formed by sequentially forming at least a photosensitive layer and a protective layer on a conductive support,
A composition obtained by reacting metal oxide fine particles having a polymerizable unsaturated group on the surface with a polymerizable compound, fluorine resin fine particles, and a charge represented by the following general formula (1): An electrophotographic photoreceptor comprising a transporting substance.
(In General Formula (1), R ₁ , R ₂ , R ₃ , and R ₄ each represent a hydrogen atom, an alkyl group having 1 to 7 carbon atoms, or an alkoxy group having 1 to 7 carbon atoms, and k, l, n Represents an integer of 1 to 5, and m represents an integer of 1 to 4. In addition, when there are a plurality of k, l, m, and n, these groups may be the same or different.   2. The electrophotographic photosensitive member according to claim 1, wherein the addition amount of the fluororesin fine particles is 5 to 70 parts by mass with respect to 100 parts by mass of the resin component in the protective layer.   3. The electrophotographic photosensitive member according to claim 1, wherein an average primary particle size of the fluororesin fine particles is 0.01 to 1 μm. The electrophotographic photosensitive member according to any one of claims 1 to 3,
Contact charging type charging means for superimposing AC;
An image forming apparatus comprising:   An image forming method comprising: forming an electrophotographic image using the image forming apparatus according to claim 4.