JP4098221B2 - Electrophotographic apparatus and process cartridge - Google Patents

Description

  The present invention relates to an electrophotographic apparatus and a process cartridge.

  In recent years, an organic (electrophotographic) photoreceptor using an organic photoconductive material has been mounted on an electrophotographic image forming apparatus. The organic photoreceptor has several characteristics, one of which is that high sensitivity is obtained for light in the visible region and light in the infrared region. For example, Patent Literature 1 and Patent Literature 2 describe a highly sensitive organic photoconductive material in the visible region, and Patent Literature 3 and Patent Literature 4 describe a highly sensitive organic photoconductive material in the infrared region. There is. Since organic photoconductors using organic photoconductive materials with high sensitivity in the infrared region match the wavelength of the laser beam, laser beam printers, digital copiers, and LED printers equipped with this have been developed. Used as an output device.

  The organophotoreceptor contains a charge generation material that generates charges by light and a charge transport material that transports the generated charges. There are various charge generation materials having sensitivity in the infrared region, but practical examples include perylene pigments, azo pigments, and phthalocyanine pigments. In particular, phthalocyanine pigments have excellent fastness and sensitivity. Titanium phthalocyanine is preferred. This pigment is called crystal polymorph, and many crystal forms are known although they are the same compound. Certain crystal forms exhibit very high sensitivity. For example, it is described in Patent Literature 5, Patent Literature 6, Patent Literature 7, and the like.

  On the other hand, there is a semiconductor laser as an exposure light source used in laser beam printers and digital copying machines. A method of forming an electrostatic latent image by reflecting a laser beam modulated by an image signal to a rotary polygon mirror and irradiating the electrophotographic photosensitive member has been developed.

In recent image formation by electrophotography, a further increase in speed is demanded. As one of the solutions, a multi-beam method in which a plurality of exposure beams are used and light is emitted simultaneously has been developed.
For example, as shown in Patent Document 8, a plurality of exposure beams are independently modulated and irradiated onto an electrophotographic photosensitive member. According to this method, for example, when two beams are used, it is possible to achieve a writing density twice as high at the same process speed as long as the conditions are matched as compared with the case where one beam is used. If the writing density is made the same, the process speed can be doubled. Further, if the process speed and the scanning density of the laser beam are made the same, there is an advantage that the rotational speed of the rotary polygon mirror can be halved and the driving device can be simplified.

  However, when this multi-beam type exposure light source is used, when the same latent image is formed, when the adjacent laser beams are emitted simultaneously and when each of the laser beams is emitted individually, There was a difference in density in the output image.

  In addition, in an electrophotographic apparatus that does not have a static elimination means such as pre-exposure, a ghost phenomenon may occur in which the history of the exposed part remains in the image at the next cycle as compared with the case of exposure with one beam. . These phenomena often appear remarkably when an electrophotographic photoreceptor using an organic photoconductive material for the photosensitive layer is repeatedly used.

  On the other hand, with respect to organic photoconductors, the diameter of photoconductors has been reduced due to the downsizing of image forming apparatuses, and the high speed of machines and the maintenance-free movement have also been added to increase the durability of photoconductors. It is coming. From this point of view, organic photoreceptors are inherently poor in chemical stability and are generally soft because they are mainly composed of low-molecular charge transport materials and inert polymers, and are repeatedly used in electrophotographic processes. In such a case, there is a drawback that wear is likely to occur due to a mechanical load by the developing system and the cleaning system. Also, due to the demand for higher image quality, the rubber hardness of the cleaning blade and the contact pressure must be increased for the purpose of increasing the cleaning property as the particle size of the toner particles is reduced. This also promotes the wear of the photoreceptor. It is a factor. Such abrasion of the photoreceptor deteriorates electrical characteristics such as sensitivity deterioration and chargeability, and causes abnormal images such as image density reduction and background stains. In addition, scratches generated as a result of local wear cause streak-like stain images due to poor cleaning. At present, it is said that the wear and scratches are rate-determined and the life of the photoconductor has been replaced.

  Therefore, it is indispensable to reduce the above-mentioned wear amount in order to increase the durability of the organic photoreceptor, and this is the most pressing issue in this field.

  Techniques for improving the abrasion resistance of the photosensitive layer include (1) using a curable binder in the crosslinkable charge transport layer (see, for example, Patent Document 9), and (2) using a polymer charge transport material. (For example, see Patent Document 10), (3) those in which an inorganic filler is dispersed in a cross-linked charge transport layer (for example, see Patent Document 11), and the like. Among these techniques, those using the curable binder (1) have poor compatibility with the charge transport material, and the residual potential increases due to impurities such as polymerization initiators and unreacted residues, resulting in a decrease in image density. Tends to occur. In addition, although the polymer charge transport material (2) can improve the abrasion resistance to some extent, the durability required for the organic photoreceptor is not fully satisfied. Not reached. In addition, polymer charge transport materials are difficult to polymerize and purify, and it is difficult to obtain a high-purity material. Therefore, it is difficult to stabilize electrical characteristics between materials. Furthermore, production problems such as high viscosity of the coating solution may occur. The dispersion of the inorganic filler (3) exhibits higher abrasion resistance than a photoreceptor in which a normal low molecular charge transport material is dispersed in an inert polymer, but the charge present on the surface of the inorganic filler. The residual potential increases due to the trap, and the image density tends to decrease. In addition, when the unevenness of the inorganic filler and the binder resin on the surface of the photoconductor is large, defective cleaning may occur, which may cause toner filming and image flow. These technologies (1), (2), and (3) are sufficient to satisfy the overall durability including the electrical durability and mechanical durability required for the organic photoreceptor. Has not reached.

  Furthermore, a photoreceptor containing a polyfunctional acrylate monomer cured product in order to improve the abrasion resistance and scratch resistance of (1) is also known (see Patent Document 12). However, in this photoreceptor, although there is a description that the polyfunctional acrylate monomer cured product is contained in the protective layer provided on the photosensitive layer, the protective layer may contain a charge transport material. However, there is a problem of compatibility with the cured product when a cross-linked charge transport layer contains a low-molecular charge transport material. As a result, precipitation of a low-molecular charge transport material and white turbidity occur, and not only the image density is lowered but also the mechanical strength is lowered due to the increase of the exposed portion potential.

  Furthermore, since this photoconductor specifically reacts with a monomer in a state containing a polymer binder, the three-dimensional network structure does not proceed sufficiently, and the crosslink density is dilute, so that the wear resistance is drastically reduced. Has not yet been able to demonstrate.

  As a wear-resistant technique for a photosensitive layer that replaces these, a charge transport layer formed by using a coating solution comprising a monomer having a carbon-carbon double bond, a charge transport agent having a carbon-carbon double bond, and a binder resin. It is known to provide (for example, refer to Patent Document 13). This binder resin is considered to play a role of improving the adhesion between the charge generation layer and the curable charge transport layer, and further mitigating the internal stress of the film during thick film curing, and has a carbon-carbon double bond. These are broadly classified into those having reactivity with the charge transfer agent and those having no reactivity with the double bond. This photoconductor is remarkably compatible with wear resistance and good electrical properties, but when a non-reactive binder resin is used, the binder resin, the monomer and the charge transport agent are used. The compatibility with the cured product produced by this reaction is poor, and layer separation occurs in the cross-linked charge transport layer, which may cause scratches and sticking of external additives and paper powder in the toner. In addition, as described above, the three-dimensional network structure does not proceed sufficiently, and the cross-linking density becomes dilute. In addition, what is specifically described as the monomer used in this photoreceptor is bifunctional, and in these respects, it has not yet been satisfactory in terms of wear resistance. Even when a reactive binder is used, the molecular weight of the cured product is increased, but the number of intermolecular crosslinks is small, and it is difficult to achieve a balance between the amount of the charge transporting substance and the crosslink density. Abrasion was not sufficient.

  A photosensitive layer containing a compound obtained by curing a hole transporting compound having two or more chain polymerizable functional groups in the same molecule is also known (see, for example, Patent Document 14). This photosensitive layer has high hardness because the crosslink density can be increased, but since the bulky hole transporting compound has two or more chain polymerizable functional groups, distortion occurs in the cured product and internal stress increases. In some cases, the crosslinked surface layer is liable to crack or peel off when used for a long period of time.

Even in the conventional photoconductors having a cross-linked photosensitive layer in which a charge transporting structure is chemically bonded, it cannot be said that the present invention has sufficient comprehensive characteristics.
JP-A-61-272754 JP 56-167759 A JP-A-57-195767 Japanese Patent Laid-Open No. 61-228453 Japanese Patent Laid-Open No. 61-239248 JP-A-62-67094 JP-A-1-17066 JP-A-60-33019 JP 56-48637 A JP-A 64-1728 JP-A-4-281461 Japanese Patent No. 3262488 Japanese Patent No. 3194392 JP 2000-66425 A

  The object of the present invention is that even when a multi-beam type exposure light source is used and no static elimination means such as pre-exposure is used, a difference in density is unlikely to occur regardless of the light emission state of the laser beam. It is an object of the present invention to provide an electrophotographic apparatus and a process cartridge that hardly cause potential fluctuations.

  Further, the object of the present invention is a high durability and high performance electrophotographic photosensitive member, which has high wear resistance and scratch resistance and good electrical characteristics, and is less susceptible to cracking and peeling of the photosensitive layer. It is an object to provide an electrophotographic apparatus using this.

According to the present invention, the following (1) to (8) are provided.
(1) An electrophotographic photosensitive member in which a photosensitive layer comprising at least a charge generation layer, a charge transporting layer, and a cross-linked charge transporting layer is provided on a support, a charging means for charging the electrophotographic photosensitive member, A multi-beam exposure unit that forms an electrostatic latent image on the electrophotographic photosensitive member using a laser beam; a developing unit that develops the electrophotographic photosensitive member on which the electrostatic latent image is formed using toner; An electrophotographic apparatus comprising: a transfer unit that transfers a toner image on a photographic photosensitive member to a transfer member; and no discharging unit that uniformly discharges an electrostatic latent image on the electrophotographic photosensitive member prior to the charging unit In
The cross-linked charge transport layer of the electrophotographic photoreceptor was formed from a cured product of at least a trifunctional or higher functional radical polymerizable monomer having no charge transport structure and a radical polymerizable compound having a monofunctional charge transport structure . ones, and the electrophotographic apparatus, wherein the charge mobility of the photosensitive layer is ^{5.0 × 10 -7 ~2.0 × 10 -5} cm 2 / V · s.

(2) The electrophotographic apparatus according to (1), wherein the electrophotographic photosensitive member has an electric field strength of 3.5 × 10 ⁵ V / cm or less.
(3) The electrophotographic apparatus according to (1) or (2), wherein the image resolution is 1200 dpi or more.
(4) The electrophotographic apparatus according to any one of (1) to (3), wherein the cross-linked charge transport layer has a thickness of 1 μm or more and 10 μm or less.
(5) The electrophotographic apparatus according to (4), wherein the thickness of the cross-linked charge transport layer is 2 μm or more and 8 μm or less.
(6) The radical polymerizable functional group of the radical polymerizable monomer having a trifunctional or higher functional group having no charge transporting structure and the monofunctional charge transporting structure having a charge transporting structure used in the crosslinkable charge transporting layer is acryloyloxy The electrophotographic apparatus according to any one of (1) to (5), wherein the electrophotographic apparatus is a group and / or a methacryloyloxy group.

(7) In the electrophotographic apparatus, at least one means selected from an electrophotographic photosensitive member, a charging means, an exposure means, a developing means, and a cleaning means is integrally supported, and is detachable from the electrophotographic apparatus main body. The electrophotographic apparatus according to any one of (1) to (6), wherein the electrophotographic apparatus constitutes a process cartridge.

(8) At least one means selected from the group consisting of an electrophotographic photosensitive member, a charging means, a developing means, and a cleaning means used in the electrophotographic apparatus described in (7) above is integrally supported and attached to and detached from the main body of the electrophotographic apparatus. A process cartridge for an electrophotographic apparatus characterized by being free.

  According to the present invention, even when a multi-beam type exposure light source is used and no static elimination means such as pre-exposure is used, a difference in density hardly occurs regardless of the light emission state of the laser beam, and ghost and repeated use Thus, it is possible to provide an electrophotographic apparatus and a process cartridge that are less likely to cause potential fluctuations.

  Further, as a crosslinked charge transport layer of a photoreceptor in which a charge generation layer, a charge transport layer, and a crosslinked charge transport layer are laminated, a trifunctional or higher functional radical polymerizable monomer having no charge transport structure and a monofunctional charge transport property are used. By using an electrophotographic photosensitive member obtained by curing a radically polymerizable compound having a structure, it is possible to provide an electrophotographic apparatus and a process cartridge in which black streaks or the like are hardly generated, potential fluctuation is small, and ghost is small.

  Furthermore, by setting the film thickness of the cross-linked charge transport layer to 1 μm or more and 10 μm or less, cracks and film peeling do not occur, wear resistance and scratch resistance are high, and in addition, good electrical characteristics are obtained. A durable and high-performance photoconductor can be obtained. Therefore, by using this photoreceptor, it is possible to provide a high-performance and highly reliable electrophotographic apparatus capable of providing a good image over a long period of time and a process cartridge.

The present invention is described in detail below.
The photoconductor used in the electrophotographic apparatus and the process cartridge of the present invention has a specific charge mobility, so that a difference in density hardly occurs regardless of the light emission state of the laser beam, and there is no neutralizing means such as pre-exposure. Even in such a case, it has an electrophotographic characteristic in which potential fluctuation due to ghost and repeated use hardly occurs.

  In an electrophotographic apparatus using a multi-beam exposure light source, there is a difference in the density of the output image between when a plurality of adjacent laser beams are simultaneously emitted and when each laser beam is individually emitted sequentially. The overlapping of the beam spots is related, and this is considered to be caused by a difference in potential characteristics of the electrophotographic photosensitive member at the overlapping portion.

  When a plurality of laser beams are emitted simultaneously, the overlapping portion of the laser spots is irradiated onto the electrophotographic photosensitive member in a state where a plurality of lights are combined. On the other hand, when the laser beams are emitted individually and sequentially, the light is irradiated twice without being synthesized.

  As described above, a phenomenon in which a difference occurs in the potential characteristics of the electrophotographic photosensitive member even though the same amount of light is irradiated is called reciprocity failure.

  In general, at the emission intensity I and the exposure time t, the light quantity E is E = I × t, and the reciprocal law is established that the potential V of the electrophotographic photosensitive member is determined as a function of the light quantity E on the electrophotographic photosensitive member. However, when the light emission intensity I is too strong or too weak, the electrophotographic photosensitive member has a different potential V because the light amount E is the same, and this is called reciprocity law failure that does not follow the reciprocity law. A phenomenon occurs. In an electrophotographic apparatus using a multi-beam type exposure light source, it is considered that the difference in the density of the output image is caused when the laser beam is simultaneously emitted because the sensitivity is lower than when the laser beam is individually emitted sequentially. .

Therefore, the present inventors have studied paying attention to the charge mobility of the electrophotographic photosensitive member, and as a result, if the charge mobility is 2.0 × 10 ⁻⁵ cm ² / V · s or less, the laser beam is individually used. It was found that when the light was emitted sequentially, it was difficult for the potential of the laser overlap to decay between the first laser irradiation and the next laser irradiation, and as a result, it was difficult to generate a potential difference from the simultaneous light emission. .

Furthermore, when the charge mobility is in the range of 5.0 × 10 ^{−7 to} 1.0 × 10 ⁻⁵ cm ² / V · s, it is found that the potential fluctuation due to ghost and repeated use hardly occurs. It came.

  The reason why such a remarkable effect can be obtained with respect to potential fluctuation due to ghost or repeated use is not clear. However, when a plurality of laser beams are used, the charge is likely to accumulate inside the electrophotographic photosensitive member because the sensitivity is deteriorated in the simultaneously emitted portion as compared with the case of a single laser beam. It is presumed that this influences the potential fluctuation due to ghost and repeated use.

  Specifically, with regard to ghosts, although moderate charge accumulation occurs by defining a specific charge mobility, it is presumed that an increase in charge accumulation due to repeated use can be suppressed, so that it is difficult to occur. In addition, regarding the potential fluctuation due to repeated use, accumulation of charge due to repeated use is appropriately maintained by defining the specific charge mobility of the present invention, which is a charge generation layer, charge transport layer or cross-linked charge transport layer. It is presumed that it is difficult to occur because it is well offset with the potential fluctuation factor that is considered to be caused by.

In the electrophotographic photoreceptor used in the present invention, the photosensitive layer has a charge mobility of 5.0 × 10 ^{−7 to} 2.0 × 10 ⁻⁵ cm ² / V · s. In particular, it is preferable to have a charge mobility of 5.0 × 10 ^{−6 to} 1.0 × 10 ⁻⁵ cm ² / V · s, and 1.5 × 10 ^{−6 to} 6.5 × 10 ⁻⁶ cm ^2. It is more preferable to have a charge mobility of / V · s.

When the charge mobility is smaller than 5.0 × 10 ⁻⁷ cm ² / V · s, the effect on the potential fluctuation due to ghost or repeated use becomes insufficient. On the other hand, if the charge mobility is larger than 2.0 × 10 ⁻⁵ cm ² / V · s, the effect on the density difference of the output image due to the emission state of the laser beam and the potential fluctuation due to repeated use becomes insufficient.

<Measurement method of charge mobility by TOF method>
The charge mobility defined in the present invention means a characteristic value defined as the charge transfer rate per unit electric field strength.
As a method for measuring the charge mobility, a method called a time-of-flight (TOF) method is usually used. This measurement method uses a sample called a sandwich cell with a structure in which both sides of the photosensitive layer are sandwiched between electrodes. An electric field is formed by applying a voltage between the electrodes, and then the sample is irradiated with pulsed light through the electrodes. Then, the waveform of the transient current flowing between the electrodes is observed in the process in which the generated charges move from one side of the sample to the opposing side. Charge mobility can be derived by analyzing this transient current waveform.

  The electrophotographic apparatus of the present invention emits a laser beam even when the electric field strength of the electrophotographic photosensitive member is small or when the influence of the overlapping portion of the laser beam spot becomes large as in the case where the resolution of the electrophotographic apparatus is high. Regardless of the state, it has an electrophotographic characteristic in which a difference in density hardly occurs, and even if there is no neutralizing means such as pre-exposure, ghosts and potential fluctuations due to repeated use hardly occur.

Specifically, even when the electric field strength of the electrophotographic photosensitive member is 3.5 × 10 ⁵ V / cm or less, particularly 3 × 10 ⁵ V / cm or less, the resolution of the electrophotographic apparatus is 1200 dpi. Even in the above cases, the density difference hardly occurs regardless of the light emission state of the laser beam, and there is an electrophotographic characteristic in which potential fluctuation due to ghosting and repeated use hardly occurs even without a static elimination means such as pre-exposure. Yes.

Hereinafter, the configuration of the electrophotographic photosensitive member used in the present invention will be described.
<About the layer structure of the electrophotographic photoreceptor>
The electrophotographic photosensitive member used in the present invention will be described with reference to the drawings.
FIG. 1 shows a photoreceptor having a laminated structure in which a charge generation layer having a charge generation function and a charge transport layer having a charge transport function are laminated on a conductive support. FIG. 1 shows a case where the cross-linked charge transport layer is a surface portion of the charge transport layer. As shown in FIGS. 2-A and B, in the present invention, a form in which the cross-linked charge transport layer occupies a certain region between the surface portion of the photosensitive layer and the charge generation layer can also be used. In other words, this cross-linked charge transport layer incorporates the chemical cross-linking structure of the present invention in the region from the surface of the charge transport layer to the charge generation layer.

<About conductive support>
Examples of the conductive support include those having a volume resistance of 10 ¹⁰ Ω · cm or less, such as metals such as aluminum, nickel, chromium, nichrome, copper, gold, silver, and platinum, tin oxide, and indium oxide. After metal oxide is deposited or sputtered, film or cylindrical plastic, paper coated, or aluminum, aluminum alloy, nickel, stainless steel, etc. Pipes that have been subjected to surface treatment such as cutting, super-finishing, and polishing can be used. Further, endless nickel belts and endless stainless steel belts disclosed in JP-A-52-36016 can also be used as the conductive support.

In addition, those obtained by dispersing and coating conductive powder in an appropriate binder resin on the support can also be used as the conductive support of the present invention.
Examples of the conductive powder include carbon black, acetylene black, metal powder such as aluminum, nickel, iron, nichrome, copper, zinc and silver, or metal oxide powder such as conductive tin oxide and ITO. Can be mentioned. The binder resin used at the same time is polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer. , Polyvinyl acetate, polyvinylidene chloride, polyarylate resin, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinyl carbazole, acrylic resin, silicone resin, epoxy resin, Examples thereof include thermoplastic, thermosetting resins, and photocurable resins such as melamine resin, urethane resin, phenol resin, and alkyd resin. Such a conductive layer can be provided by dispersing and coating these conductive powder and binder resin in a suitable solvent such as tetrahydrofuran, dichloromethane, methyl ethyl ketone, and toluene.

  Furthermore, it is electrically conductive by a heat shrinkable tube in which the conductive powder is contained in a material such as polyvinyl chloride, polypropylene, polyester, polystyrene, polyvinylidene chloride, polyethylene, chlorinated rubber, Teflon (registered trademark) on a suitable cylindrical substrate. Those provided with a conductive layer can also be used favorably as the conductive support of the present invention.

<About photosensitive layer>
(Charge generation layer)
The charge generation layer is a layer mainly composed of a charge generation material having a charge generation function, and a binder resin can be used in combination as necessary. As the charge generation material, inorganic materials and organic materials can be used.

  Inorganic materials include crystalline selenium, amorphous selenium, selenium-tellurium, selenium-tellurium-halogen, selenium-arsenic compounds, and amorphous silicon. In amorphous silicon, dangling bonds that are terminated with hydrogen atoms or halogen atoms, or those that are doped with boron atoms, phosphorus atoms, or the like are preferably used.

  On the other hand, a known material can be used as the organic material. For example, phthalocyanine pigments such as metal phthalocyanine and metal-free phthalocyanine, azulenium salt pigments, squaric acid methine pigments, azo pigments having carbazole skeleton, azo pigments having triphenylamine skeleton, azo pigments having diphenylamine skeleton, dibenzothiophene skeleton Azo pigments having a fluorenone skeleton, azo pigments having an oxadiazole skeleton, azo pigments having a bis-stilbene skeleton, azo pigments having a distyryl oxadiazole skeleton, azo pigments having a distyrylcarbazole skeleton, perylene Pigments, anthraquinone or polycyclic quinone pigments, quinoneimine pigments, diphenylmethane and triphenylmethane pigments, benzoquinone and naphthoquinone pigments, cyanine and azomethine pigments, Goido based pigments, and bisbenzimidazole pigments. These charge generation materials can be used alone or as a mixture of two or more.

  A preferred charge generating material in the present invention is oxytitanium phthalocyanine represented by the following structural formula (1).

式中、Ｘ^１、Ｘ^２、Ｘ^３及びＸ^４はＣｌまたはＢｒを示し、ｈ、ｉ、ｊ、ｋは０〜４の整数である。

In the formula, X ¹ , X ² , X ³ and X ⁴ represent Cl or Br, and h, i, j and k are integers of 0 to 4.

  In the present invention, the crystal form of oxytitanium phthalocyanine is not particularly limited, but the black angle (2θ ± 0.2 °) in the characteristic X-ray diffraction of CuKα is 9.0 °, 14.2 °, 23. It is more preferable from the viewpoint of sensitivity characteristics that either oxytitanium phthalocyanine having strong peaks at 9 ° and 27.1 ° or oxytitanium phthalocyanine having strong peaks at 9.6 ° and 27.3 ° is used. .

  As a binder resin used as necessary for the charge generation layer, polyamide, polyurethane, epoxy resin, polyketone, polycarbonate, silicone resin, acrylic resin, polyvinyl butyral, polyvinyl formal, polyvinyl ketone, polystyrene, poly-N-vinylcarbazole, Examples include polyacrylamide. These binder resins can be used alone or as a mixture of two or more. In addition to the binder resin described above as a binder resin for the charge generation layer, a polymer charge transport material having a charge transport function, such as an arylamine skeleton, benzidine skeleton, hydrazone skeleton, carbazole skeleton, stilbene skeleton, pyrazoline skeleton, etc. Polymer materials such as polycarbonate, polyester, polyurethane, polyether, polysiloxane, and acrylic resin, polymer materials having a polysilane skeleton, and the like can be used.

  Specific examples of the former include JP-A-01-001728, JP-A-01-009964, JP-A-01-013061, JP-A-01-019049, JP-A-01-241559, Japanese Unexamined Patent Publication Nos. 04-011627, 04-175337, 04-183719, 04-2225014, 04-230767, 04-320420, 05 -232727, JP-A 05-310904, JP-A 06-234836, JP-A 06-234837, JP-A 06-234838, JP-A 06-234839, JP-A 06-234840. No. 1, JP-A 06-234841, JP-A 06-239049, Japanese Unexamined Patent Publication Nos. 06-236050, 06-236051, 06-295077, 07-0756374, 08-176293, 08-208820, 08 No. -21640, JP 08-253568, JP 08-269183, JP 09-062019, JP 09-043883, JP 09-71642, JP 09-87376. JP-A 09-104746, JP-A 09-110974, JP-A 09-110976, JP-A 09-157378, JP-A 09-221544, JP-A 09-227669. JP 09-235367 A, JP 09-241369 A Charge transporting polymer materials described in JP 09-268226 A, JP 09-272735 A, JP 09-302084 A, JP 09-302085 A, JP 09-328539 A, etc. Can be mentioned.

  Specific examples of the latter include polysilylene polymers described in, for example, JP-A No. 63-285552, JP-A No. 05-19497, JP-A No. 05-70595, JP-A No. 10-73944, and the like. Illustrated.

The charge generation layer may contain a low molecular charge transport material.
Low molecular charge transport materials that can be used in the charge generation layer include hole transport materials and electron transport materials.
Examples of the electron transporting material include chloroanil, bromanyl, tetracyanoethylene, tetracyanoquinodimethane, 2,4,7-trinitro-9-fluorenone, 2,4,5,7-tetranitro-9-fluorenone, 2,4 , 5,7-tetranitroxanthone, 2,4,8-trinitrothioxanthone, 2,6,8-trinitro-4H-indeno [1,2-b] thiophen-4-one, 1,3,7-tri Examples thereof include electron-accepting substances such as nitrodibenzothiophene-5,5-dioxide and diphenoquinone derivatives. These electron transport materials can be used alone or as a mixture of two or more.

  Examples of the hole transporting material include the electron donating materials shown below and are used favorably. As hole transport materials, oxazole derivatives, oxadiazole derivatives, imidazole derivatives, monoarylamine derivatives, diarylamine derivatives, triarylamine derivatives, stilbene derivatives, α-phenylstilbene derivatives, benzidine derivatives, diarylmethane derivatives, triaryls Other known materials such as methane derivatives, 9-styrylanthracene derivatives, pyrazoline derivatives, divinylbenzene derivatives, hydrazone derivatives, indene derivatives, butadiene derivatives, pyrene derivatives, bisstilbene derivatives, enamine derivatives, and the like can be given. These hole transport materials can be used alone or as a mixture of two or more.

Methods for forming the charge generation layer include a vacuum thin film preparation method and a casting method from a solution dispersion system.
As the former method, a vacuum deposition method, a glow discharge decomposition method, an ion plating method, a sputtering method, a reactive sputtering method, a CVD method, or the like is used, and the above-described inorganic materials and organic materials can be satisfactorily formed.

  In addition, in order to provide a charge generation layer by the casting method described later, if necessary, the inorganic or organic charge generation material together with a binder resin, tetrahydrofuran, dioxane, dioxolane, toluene, dichloromethane, monochlorobenzene, dichloroethane, cyclohexanone, cyclohexane. Can be formed by dispersing with a ball mill, attritor, sand mill, bead mill, etc. using a solvent such as pentanone, anisole, xylene, methyl ethyl ketone, acetone, ethyl acetate, butyl acetate, etc. . Moreover, leveling agents, such as a dimethyl silicone oil and a methylphenyl silicone oil, can be added as needed. The coating can be performed using a dip coating method, spray coating, bead coating, ring coating method or the like.

  The thickness of the charge generation layer provided as described above is suitably about 0.01 to 5 μm, preferably 0.05 to 2 μm.

(About charge transport layer)
The charge transport layer is a layer having a charge transport function, and is formed by dissolving or dispersing a charge transport material having a charge transport function and a binder resin in an appropriate solvent, and applying and drying the solution on the charge generation layer.

  As the charge transport material, the electron transport material, hole transport material and polymer charge transport material described in the charge generation layer can be used. As described above, the use of the polymer charge transport material can reduce the solubility of the lower layer when the cross-linked charge transport layer is applied, and is particularly useful.

  As the binder resin, polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, Polyvinylidene chloride, polyarylate resin, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinyl carbazole, acrylic resin, silicone resin, epoxy resin, melamine resin, urethane resin And thermoplastic or thermosetting resins such as phenol resins and alkyd resins.

  The amount of the charge transport material is appropriately 20 to 300 parts by weight, preferably 40 to 150 parts by weight, based on 100 parts by weight of the binder resin. However, when a polymer charge transport material is used, it can be used alone or in combination with a binder resin.

  As the solvent used for coating the charge transport layer, the same solvent as that used for the charge generation layer can be used, but a solvent that dissolves the charge transport material and the binder resin well is suitable. These solvents may be used alone or in combination of two or more. In addition, the same coating method as that for the charge generation layer can be used to form the lower layer portion of the charge transport layer.

If necessary, a plasticizer and a leveling agent can be added.
As a plasticizer that can be used in combination with the charge transport layer, those used as plasticizers for general resins such as dibutyl phthalate and dioctyl phthalate can be used as they are, and the amount used is 0 with respect to 100 parts by weight of the binder resin. About 30 parts by weight is appropriate.

  Leveling agents that can be used in combination with the charge transport layer include silicone oils such as dimethyl silicone oil and methylphenyl silicone oil, and polymers or oligomers having a perfluoroalkyl group in the side chain. The amount used is a binder resin. About 0 to 1 part by weight is appropriate for 100 parts by weight.

  The thickness of the charge transport layer is suitably about 5 to 40 μm, preferably about 10 to 30 μm. On the charge transport layer thus formed, a cross-linkable charge transport layer coating solution described later is applied, dried as necessary, and a curing reaction is initiated by external energy of heat or light irradiation, thereby cross-linking charge. A transport layer is formed.

(About cross-linked charge transport layer)
The crosslinkable charge transport layer (FIGS. 1 and 2) is a layer having a crosslink structure having a charge transport function, and having at least a trifunctional or higher-functional radical polymerizable monomer having no charge transport structure and a monofunctional charge transport structure. The radically polymerizable compound is dissolved or dispersed in a suitable solvent, and this is formed by coating and drying on the charge transport layer.

The constituent materials of the crosslinkable charge transport layer coating solution of the present invention will be described.
The trifunctional or higher functional radical polymerizable monomer having no charge transporting property used in the present invention is a hole transporting structure such as triarylamine, hydrazone, pyrazoline, carbazole, such as condensed polycyclic quinone, diphenoquinone, cyano group. And a monomer having no electron transport structure such as an electron-withdrawing aromatic ring having a nitro group and having three or more radical polymerizable functional groups. The radical polymerizable functional group may be any group as long as it has a carbon-carbon double bond and is capable of radical polymerization. Examples of these radical polymerizable functional groups include 1-substituted ethylene functional groups and 1,1-substituted ethylene functional groups shown below.

(1) Examples of the 1-substituted ethylene functional group include functional groups represented by the following formulas.
CH ₂ = CH—X ₁ −... Formula 10
(In the formula, X ₁ is an arylene group such as a phenylene group or a naphthylene group which may have a substituent, an alkenylene group which may have a substituent, a —CO— group, a —COO— group. , —CON (R ₁₀ ) — group (R ₁₀ represents an alkyl group such as hydrogen, methyl group or ethyl group, an aralkyl group such as benzyl group, naphthylmethyl group or phenethyl group, or an aryl group such as phenyl group or naphthyl group. Or represents an —S— group.)
Specific examples of these substituents include a vinyl group, a styryl group, a 2-methyl-1,3-butadienyl group, a vinylcarbonyl group, an acryloyloxy group, an acryloylamide group, and a vinyl thioether group.

(2) Examples of the 1,1-substituted ethylene functional group include functional groups represented by the following formulas.
_{CH 2 = C (Y) -X} 2 - ···· formula 11
(In the formula, Y is an aryl group such as an alkyl group which may have a substituent, an aralkyl group which may have a substituent, a phenyl group which may have a substituent, or a naphthyl group. Group, halogen atom, cyano group, nitro group, alkoxy group such as methoxy group or ethoxy group, -COOR ₁₁ group (R ₁₁ is a hydrogen atom, an alkyl such as an optionally substituted methyl group or ethyl group) Group, an aralkyl group such as benzyl or phenethyl group which may have a substituent, an aryl group such as phenyl group or naphthyl group which may have a substituent, or -CONR ₁₂ R ₁₃ (R ₁₂ and R ₁₃ is a hydrogen atom, which may have a substituent an alkyl group such as methyl group and ethyl group, which may have a substituent group benzyl group, Aral such naphthylmethyl group or a phenethyl group, Le group or substituent a phenyl group which may have a represents an aryl group such as phenyl or naphthyl, which may be the same or different from each other.) Further, X ₂ is the same as X ₁ in the formula 10 substituents and a single bond, an alkylene group. However, Y, at least one oxycarbonyl group in X _2, a cyano group, an alkenylene group, and an aromatic ring.)
Specific examples of these substituents include an α-acryloyloxy chloride group, a methacryloyloxy group, an α-cyanoethylene group, an α-cyanoacryloyloxy group, an α-cyanophenylene group, and a methacryloylamino group.

In addition, examples of the substituent further substituted with the substituent for X ₁ , X ₂ , and Y include, for example, halogen groups, nitro groups, cyano groups, methyl groups, ethyl groups and other alkyl groups, methoxy groups, ethoxy groups, and the like And an aryloxy group such as a phenyl group and a naphthyl group, an aralkyl group such as a benzyl group and a phenethyl group, and the like.

  Among these radical polymerizable functional groups, acryloyloxy group and methacryloyloxy group are particularly useful, and a compound having three or more acryloyloxy groups is, for example, a compound having three or more hydroxyl groups in the molecule and an acrylic group. It can be obtained by using an acid (salt), an acrylic acid halide, or an acrylic ester to cause an ester reaction or a transesterification reaction. A compound having three or more methacryloyloxy groups can be obtained in the same manner. Further, the radical polymerizable functional groups in the monomer having three or more radical polymerizable functional groups may be the same or different.

  Specific examples of the trifunctional or higher functional radical polymerizable monomer having no charge transporting structure include the following, but are not limited to these compounds.

  That is, as the radical polymerizable monomer used in the present invention, for example, trimethylolpropane triacrylate (TMPTA), trimethylolpropane trimethacrylate, HPA modified trimethylolpropane triacrylate, ethylene oxide (EO) modified trimethylolpropane tri Acrylate, propylene oxide (PO) modified trimethylolpropane triacrylate, caprolactone modified trimethylolpropane triacrylate, HPA modified trimethylolpropane trimethacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate (PETTA), glycerol triacrylate, epichlorohydrin (ECH) ) Modified glycerol triacrylate, EO modified Lyserol triacrylate, PO-modified glycerol triacrylate, tris (acryloxyethyl) isocyanurate, dipentaerythritol hexaacrylate (DPHA), caprolactone-modified dipentaerythritol hexaacrylate, dipentaerythritol hydroxypentaacrylate, alkyl-modified dipentaerythritol pentaacrylate , Alkyl-modified dipentaerythritol tetraacrylate, alkyl-modified dipentaerythritol triacrylate, dimethylolpropane tetraacrylate (DTMPTA), pentaerythritol ethoxytetraacrylate, EO-modified phosphate triacrylate, 2,2,5,5, -tetrahydroxy Methylcyclopentanone tetraacrylate, etc. These are, may be used in combination alone or two or more types.

  The trifunctional or higher functional radical polymerizable monomer having no charge transport structure used in the present invention has a molecular weight relative to the number of functional groups in the monomer in order to form a dense crosslink in the crosslinkable charge transport layer. The ratio (molecular weight / functional group number) is preferably 250 or less. Further, when this ratio is larger than 250, the cross-linked charge transport layer is soft and wear resistance is somewhat lowered. Therefore, among the monomers exemplified above, monomers having a modifying group such as HPA, EO, PO are extremely It is not preferable to use a compound having a long modifying group alone. Further, the proportion of the trifunctional or higher functional radical polymerizable monomer having no charge transport structure used in the crosslinkable charge transport layer is 20 to 80% by weight, preferably 30 to 70% by weight based on the total amount of the crosslinkable charge transport layer. %. When the monomer component is less than 20% by weight, the three-dimensional crosslink density of the crosslinkable charge transport layer is small, and a drastic improvement in wear resistance is not achieved as compared with the case of using a conventional thermoplastic binder resin. On the other hand, if it exceeds 80% by weight, the content of the charge transporting compound is lowered, and the electrical characteristics are deteriorated. The electrical characteristics and abrasion resistance required differ depending on the process used, and the film thickness of the cross-linked charge transport layer of the photoreceptor varies accordingly. A range of 70% by weight is most preferred.

  The radical polymerizable compound having a monofunctional charge transport structure used in the crosslinked charge transport layer of the present invention is, for example, a hole transport structure such as triarylamine, hydrazone, pyrazoline, carbazole, such as condensed polycyclic quinone. , A compound having an electron transport structure such as diphenoquinone, an electron-withdrawing aromatic ring having a cyano group or a nitro group, and having one radical polymerizable functional group. Examples of the radical polymerizable functional group include those shown in the above radical polymerizable monomer, and acryloyloxy group and methacryloyloxy group are particularly useful. In addition, the triarylamine structure is highly effective as a charge transporting structure, and in particular, when a compound represented by the structure of the following general formula (1) or (2) is used, electrical characteristics such as sensitivity and residual potential are good. To last.

(In the formula, R ₁ represents a hydrogen atom, a halogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent, an aryl group which may have a substituent, a cyano group, a nitro group, Group, alkoxy group, —COOR ₇ (R ₇ is a hydrogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent or an aryl group which may have a substituent), halogen Carbonyl group or CONR ₈ R ₉ (R ₈ and R ₉ may have a hydrogen atom, a halogen atom, an alkyl group which may have a substituent, an aralkyl group which may have a substituent, or a substituent. Ar ₁ and Ar ₂ represent a substituted or unsubstituted arylene group, and may be the same or different.Ar ₃ , which may be the same or different from each other. Ar ₄ may be substituted Represents an unsubstituted aryl group, which may be the same or different, X represents a single bond, a substituted or unsubstituted alkylene group, a substituted or unsubstituted cycloalkylene group, a substituted or unsubstituted alkylene ether group, An oxygen atom, a sulfur atom, or a vinylene group, Z represents a substituted or unsubstituted alkylene group, a substituted or unsubstituted alkylene ether group, or an alkyleneoxycarbonyl group, and m and n represent an integer of 0 to 3.)

Specific examples of general formulas (1) and (2) are shown below.
In the general formulas (1) and (2), in the substituent of R ₁ , examples of the alkyl group include a methyl group, an ethyl group, a propyl group, and a butyl group, and examples of the aryl group include a phenyl group and a naphthyl group. The aralkyl group includes a benzyl group, a phenethyl group, and a naphthylmethyl group, and the alkoxy group includes a methoxy group, an ethoxy group, a propoxy group, and the like. These include a halogen atom, a nitro group, a cyano group, and a methyl group. Substituted with an alkyl group such as an ethyl group, an alkoxy group such as a methoxy group or an ethoxy group, an aryloxy group such as a phenoxy group, an aryl group such as a phenyl group or a naphthyl group, an aralkyl group such as a benzyl group or a phenethyl group, etc. May be.
Of the substituents for R ₁ , particularly preferred are a hydrogen atom and a methyl group.

Ar ₃ and Ar ₄ are substituted or unsubstituted aryl groups, and examples of the aryl group include a condensed polycyclic hydrocarbon group, a non-fused cyclic hydrocarbon group, and a heterocyclic group.
The condensed polycyclic hydrocarbon group preferably has 18 or less carbon atoms forming a ring, for example, a pentanyl group, an indenyl group, a naphthyl group, an azulenyl group, a heptaenyl group, a biphenylenyl group, an as-indacenyl group. , S-indacenyl group, fluorenyl group, acenaphthylenyl group, preadenyl group, acenaphthenyl group, phenalenyl group, phenanthryl group, anthryl group, fluoranthenyl group, acephenanthrenyl group, aceanthrylenyl group, triphenylyl group, pyrenyl group , A chrycenyl group, a naphthacenyl group, and the like.

  Examples of the non-fused cyclic hydrocarbon group include monovalent groups of monocyclic hydrocarbon compounds such as benzene, diphenyl ether, polyethylene diphenyl ether, diphenyl thioether and diphenyl sulfone, or biphenyl, polyphenyl, diphenylalkane, diphenylalkene, diphenylalkyne, Monovalent groups of non-condensed polycyclic hydrocarbon compounds such as triphenylmethane, distyrylbenzene, 1,1-diphenylcycloalkane, polyphenylalkane, and polyphenylalkene, or ring assemblies such as 9,9-diphenylfluorene And monovalent groups of hydrocarbon compounds.

  Examples of the heterocyclic group include monovalent groups such as carbazole, dibenzofuran, dibenzothiophene, oxadiazole, and thiadiazole.

Further, the aryl group represented by Ar ₃ or Ar ₄ may have a substituent as shown below, for example.
(1) Halogen atom, cyano group, nitro group and the like.
(2) Alkyl groups, preferably C ₁ -C _12, especially C ₁ -C ₈ , more preferably C ₁ -C ₄ linear or branched alkyl groups, further including fluorine atoms , a hydroxyl group, a cyano _group, an alkoxy group of C 1 -C _4, a phenyl group or a halogen _atom, which may have a phenyl group substituted by an alkoxy group C 1 -C ₄ alkyl or _C 1 -C ₄ Good. Specifically, methyl group, ethyl group, n-butyl group, i-propyl group, t-butyl group, s-butyl group, n-propyl group, trifluoromethyl group, 2-hydroxyethyl group, 2-ethoxyethyl Group, 2-cyanoethyl group, 2-methoxyethyl group, benzyl group, 4-chlorobenzyl group, 4-methylbenzyl group, 4-phenylbenzyl group and the like.

(3) An alkoxy group (—OR ₂ ), and R ₂ represents the alkyl group defined in (2). Specifically, methoxy group, ethoxy group, n-propoxy group, i-propoxy group, t-butoxy group, n-butoxy group, s-butoxy group, i-butoxy group, 2-hydroxyethoxy group, benzyloxy group And a trifluoromethoxy group.
(4) An aryloxy group, and examples of the aryl group include a phenyl group and a naphthyl group. It _may contain an alkoxy group having C 1 -C _4, alkyl group, or a halogen atom C 1 -C ₄ as a substituent. Specific examples include a phenoxy group, a 1-naphthyloxy group, a 2-naphthyloxy group, a 4-methoxyphenoxy group, and a 4-methylphenoxy group.
(5) Alkyl mercapto group or aryl mercapto group, and specific examples include methylthio group, ethylthio group, phenylthio group, p-methylphenylthio group and the like.

（式中、Ｒ_３及びＲ_４は各々独立に水素原子、前記（２）で定義したアルキル基、またはアリール基を表わす。アリール基としては、例えばフェニル基、ビフェニル基又はナフチル基が挙げられ、これらはＣ_１〜Ｃ_４のアルコキシ基、Ｃ_１〜Ｃ_４のアルキル基またはハロゲン原子を置換基として含有してもよい。Ｒ_３及びＲ_４は共同で環を形成してもよい）
具体的には、アミノ基、ジエチルアミノ基、Ｎ−メチル−Ｎ−フェニルアミノ基、Ｎ，Ｎ−ジフェニルアミノ基、Ｎ，Ｎ−ジ（トリール）アミノ基、ジベンジルアミノ基、ピペリジノ基、モルホリノ基、ピロリジノ基等が挙げられる。 (6)

(In the formula, R ₃ and R ₄ each independently represent a hydrogen atom, an alkyl group defined in (2) above, or an aryl group. Examples of the aryl group include a phenyl group, a biphenyl group, and a naphthyl group. these may form a ring _C 1 -C ₄ alkoxy _groups, C 1 -C a alkyl group or a halogen atom ₄ which may contain as substituents .R ₃ and _{R 4} jointly)
Specifically, amino group, diethylamino group, N-methyl-N-phenylamino group, N, N-diphenylamino group, N, N-di (tolyl) amino group, dibenzylamino group, piperidino group, morpholino group And pyrrolidino group.

(7) An alkylenedioxy group or an alkylenedithio group such as a methylenedioxy group or a methylenedithio group.
(8) A substituted or unsubstituted styryl group, a substituted or unsubstituted β-phenylstyryl group, a diphenylaminophenyl group, a ditolylaminophenyl group, and the like.

The arylene group represented by Ar ₁ and Ar ₂ is a divalent group derived from the aryl group represented by Ar ₃ and Ar ₄ .

  X represents a single bond, a substituted or unsubstituted alkylene group, a substituted or unsubstituted cycloalkylene group, a substituted or unsubstituted alkylene ether group, an oxygen atom, a sulfur atom, or a vinylene group.

The substituted or unsubstituted alkylene group is a C ₁ -C ₁₂ , preferably C ₁ -C ₈ , more preferably C ₁ -C ₄ linear or branched alkylene group. a fluorine atom, a hydroxyl group, a cyano _group, an alkoxy group of C 1 -C _4, a phenyl group or a halogen _atom, a phenyl group substituted with an alkyl group or a _C 1 -C ₄ alkoxy group C 1 -C ₄ It may be. Specifically, methylene group, ethylene group, n-butylene group, i-propylene group, t-butylene group, s-butylene group, n-propylene group, trifluoromethylene group, 2-hydroxyethylene group, 2-ethoxyethylene Group, 2-cyanoethylene group, 2-methoxyethylene group, benzylidene group, phenylethylene group, 4-chlorophenylethylene group, 4-methylphenylethylene group, 4-biphenylethylene group and the like.

The substituted or unsubstituted cycloalkylene _group, a cyclic alkylene group of C 5 -C _7, these are the cyclic alkylene group fluorine atom, a hydroxyl _group, an alkyl group of C 1 -C _4, a C 1 -C ₄ It may have an alkoxy group. Specific examples include a cyclohexylidene group, a cyclohexylene group, and a 3,3-dimethylcyclohexylidene group.

  The substituted or unsubstituted alkylene ether group represents ethyleneoxy, propyleneoxy, ethylene glycol, propylene glycol, diethylene glycol, tetraethylene glycol, tripropylene glycol, alkylene ether group alkylene group is hydroxyl group, methyl group, ethyl group, etc. You may have the substituent of.

で表わされ、Ｒ_５は水素、アルキル基（前記（２）で定義されるアルキル基と同じ）、アリール基（前記Ａｒ_３、Ａｒ_４で表わされるアリール基と同じ）、ａは１または２、ｂは１〜３を表わす。 The vinylene group is

R ₅ is hydrogen, an alkyl group (same as the alkyl group defined in (2) above), an aryl group (same as the aryl group represented by Ar ₃ or Ar ₄ above), a is 1 or 2 , B represents 1-3.

Z represents a substituted or unsubstituted alkylene group, a substituted or unsubstituted alkylene ether group, or an alkyleneoxycarbonyl group.
Examples of the substituted or unsubstituted alkylene group include the same alkylene groups as those described above for X.
Examples of the substituted or unsubstituted alkylene ether group include those similar to the alkylene ether group of X.
Examples of the alkyleneoxycarbonyl group include a caprolactone-modified group.

  Further, the radical polymerizable compound having a monofunctional charge transport structure of the present invention is more preferably a compound having a structure of the following general formula (3).

（式中、ｏ、ｐ、ｑはそれぞれ０又は１の整数、Ｒａは水素原子、メチル基を表わし、Ｒｂ、Ｒｃは水素原子以外の置換基で炭素数１〜６のアルキル基を表わし、複数の場合は異なっても良い。ｓ、ｔは０〜３の整数を表わす。Ｚａは単結合、メチレン基、エチレン基、

を表わす。）

(Wherein, o, p and q are each an integer of 0 or 1, Ra represents a hydrogen atom or a methyl group, Rb and Rc represent a substituent other than a hydrogen atom and an alkyl group having 1 to 6 carbon atoms, And s and t each represents an integer of 0 to 3. Za is a single bond, a methylene group, an ethylene group,

Represents. )

  As the compound represented by the above general formula, a compound having a methyl group or an ethyl group as a substituent for Rb and Rc is particularly preferable.

  The radically polymerizable compound having a monofunctional charge transport structure represented by the general formulas (1) and (2), particularly (3) used in the present invention is polymerized with the carbon-carbon double bond open on both sides. Therefore, in a polymer that is not a terminal structure but is incorporated in a chain polymer and crosslinked by polymerization with a tri- or higher functional radical polymerizable monomer, it exists in the main chain of the polymer, and Present in the cross-linked chain between the chain and the main chain (this cross-linked chain has an intermolecular cross-linked chain between one polymer and another polymer, and a site where the main chain is folded in one polymer. And other intramolecular cross-linked chains that are cross-linked with other sites derived from the polymerized monomer at positions away from this in the main chain), but even if they are present in the main chain, Even if present, the triarylamine structure suspended from the chain moiety is It has at least three aryl groups arranged in the radial direction and is bulky, but is not directly bonded to the chain part, but is suspended from the chain part via a carbonyl group, etc. Since these triarylamine structures can be arranged adjacent to each other in the polymer, there is little structural distortion in the molecule, and the surface of the electrophotographic photosensitive member is also fixed. In the case of a layer, it is presumed that an intramolecular structure that is relatively free from interruption of the charge transport pathway can be adopted.

    Specific examples of the radically polymerizable compound having a monofunctional charge transporting structure of the present invention are shown below, but are not limited to the compounds having these structures.

  In addition, the radical polymerizable compound having a monofunctional charge transport structure used in the present invention is important for imparting the charge transport performance of the crosslinkable charge transport layer, and this component ratio is relative to the crosslinkable charge transport layer. It is 20 to 80% by weight, preferably 30 to 70% by weight. If this component is less than 20% by weight, the charge transport performance of the crosslinkable charge transport layer cannot be maintained sufficiently, and deterioration of electrical characteristics such as a decrease in sensitivity and an increase in residual potential will occur with repeated use. On the other hand, if it exceeds 80% by weight, the content of the trifunctional monomer having no charge transport structure is lowered, and the crosslink density is lowered, so that high wear resistance is not exhibited. The electrical characteristics and abrasion resistance required differ depending on the process used, and the film thickness of the cross-linked charge transport layer of the photoreceptor varies accordingly. A range of 70% by weight is most preferred.

  The crosslinkable charge transport layer of the present invention is obtained by curing at least a trifunctional or higher radical polymerizable monomer having no charge transport structure and a radical polymerizable compound having a monofunctional charge transport structure. Monofunctional and bifunctional radically polymerizable monomers, functional monomers, and radical polymerization for the purpose of imparting functions such as viscosity adjustment during coating, stress relaxation of the cross-linked charge transport layer, lower surface energy and reduced friction coefficient Can be used in combination. Known radical polymerizable monomers and oligomers can be used.

  Examples of the monofunctional radical monomer include 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, tetrahydrofurfuryl acrylate, 2-ethylhexyl carbitol acrylate, 3-methoxybutyl acrylate, benzyl acrylate, and cyclohexyl acrylate. , Isoamyl acrylate, isobutyl acrylate, methoxytriethylene glycol acrylate, phenoxytetraethylene glycol acrylate, cetyl acrylate, isostearyl acrylate, stearyl acrylate, styrene monomer, and the like.

  Examples of the bifunctional radical polymerizable monomer include 1,3-butanediol diacrylate, 1,4-butanediol diacrylate, 1,4-butanediol dimethacrylate, 1,6-hexanediol diacrylate, 1, Examples include 6-hexanediol dimethacrylate, diethylene glycol diacrylate, neopentyl glycol diacrylate, EO-modified bisphenol A diacrylate, EO-modified bisphenol F diacrylate, and neopentyl glycol diacrylate.

  Examples of the functional monomer include those substituted with a fluorine atom such as octafluoropentyl acrylate, 2-perfluorooctylethyl acrylate, 2-perfluorooctylethyl methacrylate, 2-perfluoroisononylethyl acrylate, No. 60503, JP-B-6-45770, siloxane repeating units: 20-70 acryloyl polydimethylsiloxane ethyl, methacryloyl polydimethylsiloxane ethyl, acryloyl polydimethylsiloxane propyl, acryloyl polydimethylsiloxane butyl, diacryloyl polydimethylsiloxane Examples include vinyl monomers having a polysiloxane group such as diethyl, acrylates and methacrylates.

Examples of the radical polymerizable oligomer include epoxy acrylate, urethane acrylate, and polyester acrylate oligomers.
However, when a large amount of monofunctional and bifunctional radically polymerizable monomers and radically polymerizable oligomers are contained, the three-dimensional crosslink density of the crosslinkable charge transport layer is substantially reduced, resulting in a decrease in wear resistance. For this reason, the content of these monomers and oligomers is limited to 50 parts by weight or less, preferably 30 parts by weight or less, with respect to 100 parts by weight of the tri- or higher functional radical polymerizable monomer.

  The crosslinked charge transport layer of the present invention is obtained by curing at least a trifunctional or higher radical polymerizable monomer having no charge transport structure and a radical polymerizable compound having a monofunctional charge transport structure. Accordingly, a polymerization initiator may be contained in the crosslinking type charge transport layer coating solution in order to allow the curing reaction to proceed efficiently.

  Examples of the thermal polymerization initiator include 2,5-dimethylhexane-2,5-dihydroperoxide, dicumyl peroxide, benzoyl peroxide, t-butylcumyl peroxide, 2,5-dimethyl-2,5-di ( Peroxybenzoyl) hexyne-3, di-t-butyl peroxide, t-butyl hydroperoxide, cumene hydroperoxide, lauroyl peroxide, 2,2-bis (4,4-di-t-butylperoxycyclohexyl) B) Peroxide-based initiators such as propane, azo-based compounds such as azobisisobutylnitrile, azobiscyclohexanecarbonitrile, methyl azobisisobutyrate, azobisisobutylamidine hydrochloride, 4,4′-azobis-4-cyanovaleric acid Initiators are mentioned.

  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, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2- Acetophenone-based or ketal-based photopolymerization initiators such as methyl-2-morpholino (4-methylthiophenyl) propan-1-one, 1-phenyl-1,2-propanedione-2- (o-ethoxycarbonyl) oxime, Benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isobutyl ether Benzoin ether photopolymerization initiators such as benzoin isopropyl ether, benzophenone, 4-hydroxybenzophenone, methyl o-benzoylbenzoate, 2-benzoylnaphthalene, 4-benzoylbiphenyl, 4-benzoylphenyl ether, acrylated benzophenone, Benzophenone photopolymerization initiators such as 1,4-benzoylbenzene, thioxanthones such as 2-isopropylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2,4-dichlorothioxanthone Examples of photopolymerization initiators and other photopolymerization initiators include ethyl anthraquinone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoic acid. Phenylethoxyphosphine oxide, bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide, bis (2,4-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, methylphenylglyoxyester, 9,10 -Phenanthrene, an acridine type compound, a triazine type compound, an imidazole type compound is mentioned. Moreover, what has a photopolymerization acceleration effect can also be used individually or in combination with the said photoinitiator. Examples include triethanolamine, methyldiethanolamine, ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, (2-dimethylamino) ethyl benzoate, 4,4'-dimethylaminobenzophenone, and the like.

  These polymerization initiators may be used alone or in combination of two or more. The content of the polymerization initiator is 0.5 to 40 parts by weight, preferably 1 to 20 parts by weight with respect to 100 parts by weight of the total content having radical polymerizability.

  Furthermore, the crosslinkable charge transport layer coating liquid of the present invention may contain additives such as various plasticizers (for the purpose of stress relaxation and adhesion improvement), leveling agents, and low molecular charge transport materials having no radical reactivity. Can be contained. As these additives, known additives can be used, and as plasticizers, those used in general resins such as dibutyl phthalate and dioctyl phthalate can be used, and the amount used is the total solid content of the coating liquid. To 20 wt% or less, preferably 10 wt% or less. As leveling agents, silicone oils such as dimethyl silicone oil and methylphenyl silicone oil, polymers or oligomers having a perfluoroalkyl group in the side chain can be used, and the amount used is based on the total solid content of the coating liquid. 3% by weight or less is appropriate.

  The crosslinkable charge transport layer of the present invention comprises a coating liquid containing at least a trifunctional or higher functional radical polymerizable monomer having no charge transport structure and a radical polymerizable compound having a monofunctional charge transport structure. It is formed by coating and curing on the charge transport layer. When the radically polymerizable monomer is a liquid, such a coating liquid can be applied by dissolving other components in the liquid, but if necessary, it is diluted with a solvent and applied. Solvents used at this time include alcohols such as methanol, ethanol, propanol and butanol, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, esters such as ethyl acetate and butyl acetate, tetrahydrofuran, dioxane and propyl ether. And ethers such as dichloromethane, dichloroethane, trichloroethane, and chlorobenzene, aromatics such as benzene, toluene, and xylene, and cellosolves such as methyl cellosolve, ethyl cellosolve, and cellosolve acetate. These solvents may be used alone or in combination of two or more. The dilution ratio with the solvent varies depending on the solubility of the composition, the coating method, and the target film thickness, and is arbitrary. The coating can be performed using a dip coating method, spray coating, bead coating, ring coating method or the like.

In the present invention, after applying such a crosslinkable charge transport layer coating solution, energy is applied from the outside and cured to form a crosslinkable charge transport layer. The external energy used at this time includes heat, light, and the like. , There is radiation. The heat energy is applied by heating from the coating surface side or the support side using a gas such as air or nitrogen, steam, various heat media, infrared rays, or electromagnetic waves. The heating temperature is preferably 100 ° C. or more and 170 ° C. or less, and if it is less than 100 ° C., the reaction rate is slow and the curing reaction is not completely completed. When the temperature is higher than 170 ° C., the curing reaction proceeds non-uniformly, and large strains, a large number of unreacted residues, and reaction termination terminals are generated in the cross-linked charge transport layer. In order to advance the curing reaction uniformly, it is also effective to complete the reaction by heating at a relatively low temperature of less than 100 ° C. and then heating to 100 ° C. or more. As the energy of light, UV irradiation light sources such as high-pressure mercury lamps and metal halide lamps, which mainly have an emission wavelength in ultraviolet light, can be used, but a visible light source can also be selected according to the absorption wavelength of radically polymerizable substances and photopolymerization initiators. Is possible. Irradiation light amount is 50 mW / cm ² or more, preferably 1000 mW / cm ² or less, it takes time for the curing reaction is less than 50 mW / cm ^2. If it is higher than 1000 mW / cm ^2, the progress of the reaction becomes non-uniform, and local flaws are generated on the surface of the cross-linked charge transport layer, or many unreacted residues and reaction termination ends are generated. In addition, internal stress increases due to rapid crosslinking, which causes cracks and film peeling. Examples of radiation energy include those using electron beams. Among these energies, those using heat and light energy are useful because of the ease of reaction rate control and the simplicity of the apparatus.

  The film thickness of the crosslinked charge transport layer of the present invention is usually 1 μm or more and 20 μm or less, although it depends on the material used. Preferably they are 1 micrometer or more and 10 micrometers or less, More preferably, they are 2 micrometers or more and 8 micrometers or less. If it is thicker than 10 μm, cracks and film peeling are likely to occur as described above, and if it is 8 μm or less, the margin is further improved, so that the crosslink density can be increased, and material selection and curing that further increases wear resistance. Conditions can be set. On the other hand, the radical polymerization reaction is prone to oxygen inhibition, that is, the surface in contact with the air is not easily cross-linked or non-uniform due to the effect of radical trapping by oxygen. This effect is noticeable when the surface layer is less than 1 μm, and the cross-linked charge transport layer having a thickness less than this thickness tends to have a reduced wear resistance and uneven wear. In addition, mixing of the lower layer charge transport layer component occurs during the application of the crosslinkable charge transport layer. If the coating thickness of the crosslinkable charge transport layer is thin, contaminants spread throughout the layer, which inhibits the curing reaction and lowers the crosslink density. For these reasons, the cross-linkable charge transport layer of the present invention has good wear resistance and scratch resistance at a film thickness of 1 μm or more, but it can be locally scraped to the lower charge transport layer in repeated use. The wear of the portion increases, and the density unevenness of the halftone image tends to occur due to the chargeability and sensitivity fluctuation. Therefore, it is desirable that the film thickness of the crosslinkable charge transport layer be 2 μm or more for a longer life and higher image quality.

  The composition of the crosslinkable charge transport layer coating solution includes radical polymerization in addition to the above-described trifunctional or higher-functional radical polymerizable monomer having no charge transport structure and a radical polymerizable compound having a monofunctional charge transport structure. When a large amount of additives such as binder resins, antioxidants, and plasticizers that do not have a functional functional group are contained, the crosslinking density is lowered, and the cured product resulting from the reaction and phase separation of the above additives occur, resulting in an organic solvent. It becomes soluble to. Specifically, it is important to suppress the total content to 20% by weight or less with respect to the total solid content of the coating liquid. Further, in order not to dilute the crosslinking density, the total content of monofunctional or bifunctional radical polymerizable monomers, reactive oligomers, and reactive polymers is 20% by weight or less based on the trifunctional radical polymerizable monomers. It is desirable. Further, when a large amount of a radically polymerizable compound having a bifunctional or higher-functional charge transporting structure is contained, a bulky structure is fixed in the crosslinked structure by a plurality of bonds, so that distortion is likely to occur. It is easy to become an aggregate. This can cause solubility in organic solvents. Although different depending on the compound structure, the content of the radical polymerizable compound having a bifunctional or higher functional charge transporting structure is preferably 10% by weight or less based on the radical polymerizable compound having a monofunctional charge transporting structure.

  In addition, in order to achieve wear resistance and scratch resistance, in the configuration in which a charge generation layer, a charge transport layer, and a crosslinkable charge transport layer are sequentially laminated, the outermost crosslinkable charge transport layer is insoluble in an organic solvent. Is preferable. In the constitution of the present invention, in order to make the crosslinkable charge transport layer insoluble in the organic solvent, (1) composition of the crosslinkable charge transport layer coating solution, adjustment of the content ratio thereof, (2) crosslinkable charge Dilution solvent of transport layer coating solution, adjustment of solid content concentration, (3) Selection of coating method of crosslinkable charge transport layer, (4) Control of curing condition of crosslinkable charge transport layer, (5) Charge of lower layer It is important to control these, such as making the transport layer difficult to dissolve, but it is not achieved by a single factor.

  Regarding the diluting solvent of the crosslinkable charge transport layer coating solution, if a solvent with a low evaporation rate is used, the remaining solvent may interfere with curing or increase the amount of the lower layer component mixed, resulting in uneven curing. And the cured density is reduced. For this reason, it tends to be soluble in organic solvents. Specifically, tetrahydrofuran, a mixed solvent of tetrahydrofuran and methanol, ethyl acetate, methyl ethyl ketone, ethyl cellosolve and the like are useful, but are selected according to the coating method. Moreover, regarding the solid content concentration, if it is too low for the same reason, it tends to be soluble in an organic solvent. Conversely, the upper limit concentration is constrained by the limitations of film thickness and coating solution viscosity. Specifically, it is desirable to use in the range of 10 to 50% by weight. As the coating method for the cross-linked charge transport layer, for the same reason, the solvent content at the time of forming the coating film, the method of reducing the contact time with the solvent is preferable, specifically, the spray coating method, the amount of coating liquid A ring coat method in which the above is regulated is preferable. In order to suppress the amount of the lower layer component mixed, it is also effective to use a polymer charge transport material as the charge transport layer and to provide an insoluble intermediate layer for the coating solvent for the cross-linked charge transport layer.

As curing conditions for the cross-linked charge transport layer, if the energy of heating or light irradiation is low, the curing is not completely completed and the solubility in the organic solvent is increased. On the other hand, when cured with very high energy, the curing reaction becomes non-uniform, and it tends to increase the number of uncrosslinked parts and radical stopping parts and to form an aggregate of minute cured products. For this reason, it may become soluble in an organic solvent. In order to insolubilize in an organic solvent, the heat curing conditions are preferably 100 to 170 ° C. and 10 minutes to 3 hours, and the curing conditions by UV light irradiation are 50 to 1000 mW / cm ² and 5 seconds to 5 minutes. In addition, it is desirable to control the temperature rise to 50 ° C. or less to suppress non-uniform curing reaction.

  In the structure of the present invention, an example of a method for making the crosslinkable charge transport layer insoluble in an organic solvent is, for example, an acrylate monomer having three acryloyloxy groups and a triaryl having one acryloyloxy group as a coating solution. When using an amine compound, the ratio of use is 7: 3 to 3: 7, and 3 to 20% by weight of a polymerization initiator is added to the total amount of these acrylate compounds, and a solvent is added to the coating solution. To prepare. For example, in the charge transport layer that is the lower layer of the cross-linked charge transport layer, when the surface layer is formed by spray coating using a triarylamine donor as the charge transport material and polycarbonate as the binder resin, the above coating is used. As the solvent of the liquid, tetrahydrofuran, 2-butanone, ethyl acetate and the like are preferable, and the use ratio is 3 to 10 times the total amount of the acrylate compound.

  Next, for example, the prepared coating solution is applied by spraying or the like on a photoreceptor in which an undercoat layer, a charge generation layer, and the charge transport layer are sequentially laminated on a support such as an aluminum cylinder. Thereafter, it is naturally dried or dried at a relatively low temperature for a short time (25 to 80 ° C., 1 to 10 minutes) and cured by UV irradiation or heating.

For UV irradiation, uses a metal halide lamp, illuminance 50 mW / cm ² or more, preferably 1000 mW / cm ² or less, for example, the case of irradiation with UV light of 600 mW / cm ^2, for example upon curing, the drum of a plurality of lamps What is necessary is just to irradiate the circumferential direction uniformly about 90 seconds. At this time, the drum temperature is controlled so as not to exceed 50 ° C.

  In the case of thermosetting, the heating temperature is preferably 100 to 170 ° C. For example, when a blowing oven is used as a heating means and the heating temperature is set to 150 ° C, the heating time is 20 minutes to 3 hours.

  After the curing is completed, the electrophotographic photosensitive member of the present invention is obtained by further heating at 100 to 150 ° C. for 10 to 30 minutes to reduce the residual solvent.

The following factors can be cited as reasons why the object can be achieved by using the electrophotographic photosensitive member of the present invention.
The electrophotographic photosensitive member is used in an environment where a series of processes of a charging unit, a developing unit, a transfer unit, a cleaning unit, and a static eliminating unit are repeated. Causes life. Factors that cause this wear and scratch are (1) charging, decomposition of the photoreceptor surface composition due to discharge during static elimination and chemical degradation due to oxidizing gas, (2) carrier adhesion during development, (3) during transfer (4) Friction with cleaning brush, cleaning blade and intervening toner or adhering carrier at the time of cleaning. In order to design a photoreceptor that is resistant to these hazards, it is important that the surface layer has high hardness, high elasticity, and uniformity. From the film structure, there is a method of forming a dense and homogeneous three-dimensional network structure. Promising.

  The cross-linked charge transport layer corresponding to the surface layer of the photoreceptor of the present invention has a cross-linked structure obtained by curing a tri- or higher-functional radical polymerizable monomer, so that a three-dimensional network structure is developed, the cross-link density is very high, and the hardness is high. An elastic surface layer is obtained, and high wear resistance and scratch resistance are achieved.

  In this way, it is important to increase the crosslink density on the surface of the photoreceptor, that is, the number of crosslink bonds per unit volume. However, since a large number of bonds are instantaneously formed in the curing reaction, internal stress due to volume shrinkage occurs. This internal stress increases as the thickness of the cross-linked layer increases. Therefore, when the entire charge transport layer is cured, cracks and film peeling tend to occur. Even if this phenomenon does not appear initially, it may be likely to occur over time due to repeated use in the electrophotographic process and the influence of charging, development, transfer, cleaning hazards and thermal fluctuations. As a method for solving this problem, (1) a polymer component is introduced into the crosslinked layer and the crosslinked structure, (2) a large amount of monofunctional and bifunctional radically polymerizable monomers are used, and (3) a flexible group is introduced. Although the directionality which makes a cured resin layer soft, such as using the polyfunctional monomer which has, is mentioned, the crosslink density of a bridge | crosslinking layer becomes thin in any case, and remarkable wear resistance is not achieved.

  On the other hand, the photoconductor of the present invention is provided with a cross-linked charge transport layer having a high cross-linking density and having a three-dimensional network structure developed on the charge transport layer with a film thickness of 1 μm or more and 10 μm or less. No film peeling occurs and very high wear resistance is achieved. By selecting a film thickness of the crosslinkable charge transport layer of 2 μm or more and 8 μm or less, the margin for the above problem is further improved, and a material for increasing the crosslink density that leads to further improvement of wear resistance is selected. Is possible. The reason why the photoconductor of the present invention can suppress cracking and film peeling is that the cross-linked charge transport layer can be made thin, so that the internal stress does not increase, and since the charge transport layer is provided in the lower layer, the surface of the cross-linked charge transport layer This is because internal stress can be relaxed. For this reason, it is not necessary to contain a large amount of polymer material in the cross-linked charge transport layer, and the polymer material and radical polymerizable composition (radical polymerizable monomer or radical polymerizable compound having a charge transport structure) generated at this time. Scratches and toner filming due to incompatibility with the cured product resulting from this reaction are unlikely to occur.

  Furthermore, when a thick film over the entire charge transport layer is cured by light energy irradiation, light transmission from the absorption by the charge transport structure to the inside is limited, and a phenomenon in which the curing reaction does not proceed sufficiently may occur. In the cross-linked charge transport layer of the present invention, the curing reaction proceeds uniformly from a thin film of 10 μm or less to the inside, and high wear resistance is maintained inside as well as the surface.

  In addition, in the formation of the outermost surface layer of the present invention, in addition to the trifunctional radical polymerizable monomer, a radical polymerizable compound having a monofunctional charge transporting structure is further contained, which is a trifunctional or higher functional group. Incorporated into the cross-linking during curing of the radical polymerizable monomer. On the other hand, when a low molecular charge transport material having no functional group is contained in the cross-linked surface layer, precipitation of the low molecular charge transport material and white turbidity occur due to its low compatibility, and the cross-linked surface layer The mechanical strength also decreases. On the other hand, when a bifunctional or higher-functional charge transporting compound is used as the main component, the crosslink structure is fixed by a plurality of bonds and the crosslink density is further increased. However, the charge transporting structure is very bulky, so that the cured resin structure is distorted. Becomes very large, which increases the internal stress of the cross-linked charge transport layer.

  Furthermore, the photoreceptor of the present invention has good electrical characteristics, and thus high image quality can be realized over a long period of time. This is because a radically polymerizable compound having a monofunctional charge transporting structure is used as a constituent material of the crosslinkable charge transport layer and is immobilized in a pendant shape between the crosslinks. As described above, the charge transport material having no functional group causes precipitation and clouding phenomenon, and the electrical characteristics are remarkably deteriorated in repeated use such as reduction in sensitivity and increase in residual potential. When a bifunctional or higher-functional charge transporting compound is used as the main component, it is fixed in the crosslinked structure with a plurality of bonds, so the intermediate structure (cation radical) during charge transport cannot be kept stable, Sensitivity decreases due to traps and residual potential increases. Such deterioration of the electrical characteristics appears as an image such as a decrease in image density and thinning of characters. Further, in the photoreceptor of the present invention, the high charge mobility design with less charge trapping of the conventional photoreceptor can be applied as the lower charge transport layer, and the electrical side effects of the crosslinked charge transport layer can be minimized. .

  The cross-linked charge transport layer of the present invention is formed by curing a tri- or higher functional radical polymerizable monomer having no charge transport structure and a radical polymerizable compound having a monofunctional charge transport structure. Although a three-dimensional network structure develops and has a high crosslinking density, it contains from other than the above components (for example, mono- or bifunctional monomers, polymer binders, antioxidants, leveling agents, plasticizers and other additives and lower layers) In some cases, the cross-linking density is locally dilute or the aggregate is formed of fine cured products cross-linked with high density. Such a crosslinkable charge transport layer has a weak bonding force between cured products and is soluble in an organic solvent, and is repeatedly used in an electrophotographic process. Elimination is likely to occur. By making the cross-linkable charge transport layer insoluble in organic solvents, the original three-dimensional network structure develops and has a high degree of cross-linking, and the chain reaction proceeds in a wide range and the cured product has a high molecular weight. Therefore, dramatic wear resistance is achieved.

<About the intermediate layer>
In the photoreceptor of the present invention, an intermediate layer is provided between the charge transport layer and the cross-linked charge transport layer for the purpose of suppressing charge transport layer component mixing into the cross-linked charge transport layer or improving adhesion between the two layers. It is possible. For this reason, as the intermediate layer, those which are insoluble or hardly soluble in the cross-linked charge transport layer coating solution are suitable, and generally a binder resin is used as a main component. Examples of these resins include polyamide, alcohol-soluble nylon, water-soluble polyvinyl butyral, polyvinyl butyral, and polyvinyl alcohol. As a method for forming the intermediate layer, a generally used coating method is employed as described above. In addition, about 0.05-2 micrometers is suitable for the thickness of an intermediate | middle layer.

<About the undercoat layer>
In the photoreceptor of the present invention, an undercoat layer can be provided between the conductive support and the photosensitive layer. In general, the undercoat layer is mainly composed of a resin. However, considering that the photosensitive layer is coated with a solvent on these resins, the resin may be a resin having high solvent resistance with respect to a general organic solvent. desirable. Examples of such resins include water-soluble resins such as polyvinyl alcohol, casein, and sodium polyacrylate, alcohol-soluble resins such as copolymer nylon and methoxymethylated nylon, polyurethane, melamine resin, phenol resin, alkyd-melamine resin, and epoxy. Examples thereof include a curable resin that forms a three-dimensional network structure such as a resin. Further, a metal oxide fine powder pigment exemplified by titanium oxide, silica, alumina, zirconium oxide, tin oxide, indium oxide and the like may be added to the undercoat layer in order to prevent moire and reduce residual potential.

These undercoat layers can be formed using an appropriate solvent and a coating method like the above-mentioned photosensitive layer. Furthermore, a silane coupling agent, a titanium coupling agent, a chromium coupling agent, or the like can be used as the undercoat layer of the present invention. In addition, in the undercoat layer of the present invention, Al ₂ O ₃ is provided by anodic oxidation, organic matter such as polyparaxylylene (parylene), SiO ₂ , SnO ₂ , TiO ₂ , ITO, CeO ₂ A material provided with an inorganic material such as a vacuum thin film can also be used favorably. In addition, known ones can be used. The thickness of the undercoat layer is suitably from 0 to 5 μm.

<Addition of antioxidant to each layer>
Further, in the present invention, in order to improve environmental resistance, in particular, for the purpose of preventing a decrease in sensitivity and an increase in residual potential, a cross-linked charge transport layer, a charge transport layer, a charge generation layer, an undercoat layer, an intermediate layer An antioxidant can be added to each layer.

The following are mentioned as antioxidant which can be used for this invention.
(Phenolic compounds)
2,6-di-t-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-t-butyl-4-ethylphenol, stearyl-β- (3,5-di-t-butyl-4 -Hydroxyphenyl) propionate, 2,2'-methylene-bis- (4-methyl-6-tert-butylphenol), 2,2'-methylene-bis- (4-ethyl-6-tert-butylphenol), 4, 4'-thiobis- (3-methyl-6-tert-butylphenol), 4,4'-butylidenebis- (3-methyl-6-tert-butylphenol), 1,1,3-tris- (2-methyl-4 -Hydroxy-5-t-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, tetrakis- [methylene- -(3 ', 5'-di-t-butyl-4'-hydroxyphenyl) propionate] methane, bis [3,3'-bis (4'-hydroxy-3'-t-butylphenyl) butyric acid] Crycol esters, tocopherols, etc.

(Paraphenylenediamines)
N-phenyl-N'-isopropyl-p-phenylenediamine, N, N'-di-sec-butyl-p-phenylenediamine, N-phenyl-N-sec-butyl-p-phenylenediamine, N, N'- Di-isopropyl-p-phenylenediamine, N, N′-dimethyl-N, N′-di-t-butyl-p-phenylenediamine and the like.

(Hydroquinones)
2,5-di-t-octylhydroquinone, 2,6-didodecylhydroquinone, 2-dodecylhydroquinone, 2-dodecyl-5-chlorohydroquinone, 2-t-octyl-5-methylhydroquinone, 2- (2-octadecenyl) ) -5-methylhydroquinone and the like.

(Organic sulfur compounds)
Dilauryl-3,3′-thiodipropionate, distearyl-3,3′-thiodipropionate, ditetradecyl-3,3′-thiodipropionate, and the like.

(Organic phosphorus compounds)
Triphenylphosphine, tri (nonylphenyl) phosphine, tri (dinonylphenyl) phosphine, tricresylphosphine, tri (2,4-dibutylphenoxy) phosphine, and the like.

These compounds are known as antioxidants such as rubbers, plastics and fats and oils, and commercially available products can be easily obtained.
The addition amount of the antioxidant in the present invention is 0.01 to 10% by weight based on the total weight of the layer to be added.

<Synthesis example of compound having monofunctional charge transport structure>
The compound having a monofunctional charge transport structure in the present invention is synthesized, for example, by the method described in Japanese Patent No. 3164426. An example of this is shown below.

(1) Synthesis of hydroxy group-substituted triarylamine compound (the following structural formula B) 113.85 g (0.3 mol) of a methoxy group-substituted triarylamine compound (the following structural formula A) and 138 g (0.92 mol) of sodium iodide To this, 240 ml of sulfolane was added and heated to 60 ° C. in a nitrogen stream. In this liquid, 99 g (0.91 mol) of trimethylchlorosilane was added dropwise over 1 hour and stirred at a temperature of about 60 ° C. for 4 and a half hours to complete the reaction. About 1.5 L of toluene was added to the reaction solution, cooled to room temperature, and washed repeatedly with water and an aqueous sodium carbonate solution. Thereafter, the solvent was removed from the toluene solution and purified by column chromatography (adsorption medium: silica gel, developing solvent: toluene: ethyl acetate = 20: 1). Cyclohexane was added to the obtained pale yellow oil to precipitate crystals. In this way, 88.1 g (yield = 80.4%) of white crystals of the following structural formula B was obtained.
Melting point: 64.0-66.0 ° C

(2) Triarylamino group-substituted acrylate compound (Exemplary Compound No. 54 in Table 1)
82.9 g (0.227 mol) of the hydroxy group-substituted triarylamine compound (Structural Formula B) obtained in (1) above was dissolved in 400 ml of tetrahydrofuran, and an aqueous sodium hydroxide solution (NaOH: 12.4 g, Water: 100 ml) was added dropwise. The solution was cooled to 5 ° C., and 25.2 g (0.272 mol) of acrylic acid chloride was added dropwise over 40 minutes. Then, it stirred at 5 degreeC for 3 hours, and reaction was complete | finished. The reaction solution was poured into water and extracted with toluene. This extract was repeatedly washed with an aqueous sodium bicarbonate solution and water. Thereafter, the solvent was removed from the toluene solution and purified by column chromatography (adsorption medium: silica gel, developing solvent: toluene). N-Hexane was added to the obtained colorless oil to precipitate crystals. In this way, Exemplified Compound No. As a result, 80.73 g (yield = 84.8%) of 54 white crystals were obtained.
Melting point: 117.5-119.0 ° C

<About electrophotographic equipment>
Next, the electrophotographic apparatus of the present invention will be specifically described.
A configuration example of the electrophotographic apparatus of the present invention is shown in FIG. The apparatus shown in FIG. 3 includes a roller-shaped charging member 1 as a charging unit on the peripheral surface of the electrophotographic photosensitive member 2, a multi-beam image exposure unit 15, a developing unit 16, a paper feed roller and paper feed guide 17, and a transfer unit 18. A cleaning means 19 is arranged. In the image forming method, first, a voltage is applied to the charging member 1 disposed in contact with the electrophotographic photosensitive member 2, the surface of the photosensitive member 2 is charged, and the multi-beam exposure light source 15 having a plurality of laser beams is used. The photoreceptor 2 is exposed to an image to form an electrostatic latent image. Next, the electrostatic latent image on the photoreceptor 2 is developed by attaching toner to the photoreceptor 2 by the developing means 16. Further, the toner image formed on the photosensitive member 2 is transferred by a transfer charger 18 onto a transfer material such as paper supplied through a paper supply roller and a paper supply guide 17 and is not transferred to the transfer material by a cleaning unit 19. The residual toner remaining on the photoreceptor 2 is collected. On the other hand, the transfer material on which the toner image is formed is sent to a fixing device (not shown) by a transport unit (not shown) to fix the toner image. In this electrophotographic apparatus, laser light or the like is used for the exposure light source 15, but other auxiliary processes may be added as necessary.

  In the present invention, a plurality of components such as the electrophotographic photosensitive member 2, the charging member 1, the developing unit 16, and the cleaning unit 19 described above are integrally coupled as a process cartridge. You may comprise so that attachment or detachment with respect to electrophotographic apparatus main bodies, such as a copying machine and a laser beam printer, is possible. For example, at least one of the charging member 1, the developing unit 16, and the cleaning unit 19 may be integrally supported with a photosensitive member to form a cartridge, and a process cartridge that can be attached to and detached from the apparatus main body using guide means such as a rail of the apparatus main body. Good. An example of the process cartridge is shown in FIG.

Next, the exposure means used in the present invention will be described.
FIG. 5 shows a schematic configuration of a multi-beam type exposure means having a plurality of laser beams.
This multi-beam scanning device includes a semiconductor laser diode array 30 having a plurality of light sources in an array, a collimating lens 35, a cylinder lens 31, a rotary polygon mirror 32 that is a deflection scanning means for a light beam, an fθ lens system 33, and a toroidal lens. 34, a reflecting mirror 38, a photosensitive drum 36, and a photo detector 37 for detecting a scanning start time for each scanning and obtaining a synchronization signal.

  First, a plurality of laser beams emitted from the semiconductor laser array 30 are converted into a parallel light beam or a substantially parallel light beam by the collimator lens 35, and are incident on a deflection scanning unit including a rotary polygon mirror 32 through the cylinder lens 31. Then, by rotating the rotary polygon mirror 32, scanning is repeated in the main scanning direction. The laser beam reflected by the rotating polygonal mirror 32 becomes convergent light by the fθ lens 33 and the toroidal lens 34 which are an imaging system, and a photodetector 37 is provided outside the region of the effective mirror. The laser beam is detected and synchronized in the scanning direction for each scan.

EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to a following example. Note that “parts” used in the examples all represent parts by weight.
Example 1
Preparation of photoconductor A 5% methanol solution of polyamide resin (CM8000, Toray) was applied on an Al pipe (φ30mm × 350mm) that had been cut to prevent moiré, by an immersion method, and an undercoat layer of 0.3μm Was established.
Next, 10 parts of oxytitanium phthalocyanine having strong peaks at 9.0 °, 14.2 °, 23.9 ° and 27.1 ° of the Bragg angle (2θ ± 0.2 °) in the characteristic X-ray diffraction of CuKα And 10 parts of polyvinyl butyral (ESREC BM2, Sekisui Chemical Co., Ltd.) and 60 parts of cyclohexanone were dispersed in a sand mill using glass beads having a diameter of 1 mm for 20 hours. 100 parts of methyl ethyl ketone was added to this dispersion to obtain a charge generation layer coating solution. This coating solution was dip-coated on the undercoat layer and dried to form a charge generation layer having a thickness of 0.12 μm.

下記構造式（３）の化合物２部、 Next, 8 parts of the compound of the following structural formula (2),

2 parts of the compound of the following structural formula (3),

をポリカーボネートＺ樹脂（重量平均分子量２８，０００）１２部及びモノクロルベンゼン６０部に溶解した。この溶液を上記電荷発生層上に塗布し、乾燥することによって電荷輸送層を形成した。膜厚は２０μｍであった。

Was dissolved in 12 parts of polycarbonate Z resin (weight average molecular weight 28,000) and 60 parts of monochlorobenzene. This solution was applied onto the charge generation layer and dried to form a charge transport layer. The film thickness was 20 μm.

Further, the cross-linked charge transport layer coating liquid I having the following composition was spray-coated on this charge transport layer, naturally dried for 20 minutes, and then irradiated with a metal halide lamp at an irradiation distance of 120 mm at an irradiation intensity of 600 mW / Light was irradiated at an irradiation time of 60 seconds at cm ² to cure the coating film. Further, drying was performed at 130 ° C. for 20 minutes, and a 5.0 μm cross-linked charge transport layer was provided to obtain an electrophotographic photosensitive member. This cross-linked charge transport layer is referred to as Type I.

[Coating liquid I for crosslinkable charge transport layer]
Trifunctional or higher radical polymerizable monomer having no charge transport structure 10 parts {Trimethylolpropane triacrylate (KAYARAD TMPTA, Nippon Kayaku)
Molecular weight: 296, number of functional groups: trifunctional, molecular weight / number of functional groups = 99}
10 parts of a radically polymerizable compound having a monofunctional charge transporting structure (Exemplary Compound No. 54)
Photopolymerization initiator 1 part {1-hydroxy-cyclohexyl-phenyl-ketone (Irgacure 184, manufactured by Ciba Specialty Chemicals)}
Tetrahydrofuran 100 parts

Measurement of charge mobility An electrophotographic photosensitive layer similar to the above was provided on an Al vapor-deposited sheet, and a semi-transparent gold electrode was vacuum-deposited on the surface thereof to produce a sample for charge mobility measurement.
The TOF method was used for measuring the charge mobility. As a method, after applying a voltage to the measurement sample so as to be the same potential as the dark part potential, pulse light irradiation is performed by a laser diode having a wavelength of 680 nm to generate charges from the charge generation layer, and the generated transient current waveform is Measurement was performed using a high-speed current amplifier (Keutley 428) and a digital oscilloscope (Tektronix TDS420A). For the determination of the transit time, a method (Scher-Control method) in which the relationship between the current I and the time t is logarithmically converted and obtained from the inflection point of the obtained curve is used.

Calculation of electric field strength The electric field strength is calculated by adding the dark portion potential Vd (V) of the electrophotographic apparatus equipped with the photoreceptor of the present invention to the total of the charge generation layer of the photosensitive layer and the charge transport layer (including the cross-linked charge transport layer). The value Vd / L (V / cm) obtained by dividing by the film thickness L (cm) can be used as the electric field strength. The total film thickness L (cm) can be substituted with substantially the thickness of the charge transport layer because the specific resistance and thickness of the charge transport layer are much larger than those of the other layers.

  Next, the electrophotographic apparatus will be described. A Hewlett-Packard LBP “Laser Jet 4000” (process speed 94 mm / s, resolution 600 dpi) was used after modification. The exposure light source was modified from a single laser beam to a multi-beam system having two laser beams. Prior to the charging means, there is no neutralizing means for uniformly eliminating the electrostatic latent image on the electrophotographic photosensitive member. Further, the potential setting was adjusted so that the dark portion potential was −700 V and the light portion potential was −150 V.

Evaluation Using the produced electrophotographic photosensitive member, a halftone image composed of two dot lines simultaneously emitting laser beams with the above apparatus and a halftone image composed of two dot lines sequentially emitting each laser beam were output. The difference in image density was evaluated by visual evaluation as follows.
(Visual evaluation)
A: The density difference is unknown. B: The density difference is slightly. C: The density difference is. (The good level is C1 and the bad level is C2.)
D: There is a large density difference

Next, with this device, continuous printing is performed for 5,000 sheets in an environment of 23 ° C. and 50% RH, and an ghost is evaluated by outputting an image pattern in which the black color after 25 mm square is halftone after the initial and 5000 sheets. went. The durable image was a horizontal line pattern with a printing rate of 5%. The following ranking was made by visual evaluation.
(Visual evaluation)
About halftone after solid black
A: The ghost cannot be confirmed in the halftone B: The density is slightly darker than the other halftones C: The density is darker than the other halftones (C1: good level, C2: bad level)
D: Clearly darker than other halftones. On the contrary, the halftone after solid black is thinner than other halftones.
B ': The density is slightly lighter than other halftones. C': The density is lighter than other halftones.
(C'1: good level, C'2: bad level)
D ': clearly thinner than other halftones

  Further, 5000 sheets of intermittent paper-passing output that stops once for each print in an environment of 23 ° C./50% RH was performed with this apparatus, and the potential characteristics were evaluated. In the image, solid white, solid black, halftone, a character pattern with a printing rate of 4%, and a horizontal line pattern with a printing rate of 5% were randomly combined. In the evaluation, the bright portion potential was measured at the initial stage and every 200 sheets, and the difference between the two points having the largest potential difference through the 5000 sheets from the initial stage was determined.

  Thereafter, 10,000 sheets were repeatedly output, and the potential characteristics of 10,000 sheets were evaluated. In the evaluation, the bright portion potential was measured at the initial stage and every 200 sheets, and the difference between the two points having the largest potential difference through the 10,000 sheets from the initial stage was taken.

  Further, the output was continuously repeated for 50000 sheets to evaluate the wear amount of the photoreceptor. Meanwhile, if there was any abnormality in the photoreceptor during running, it was observed. The results are shown in Table 1.

(Example 2)
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the thickness of the charge transport layer was 15 μm, and evaluated in the same manner.

(Example 3)
An electrophotographic photosensitive member was prepared and evaluated in the same manner as in Example 1 except that 5 parts of the compound of the structural formula (2) and 1 part of the compound of the structural formula (3) were used as the charge transport material for the charge transport layer. did.

Example 4
An electrophotographic photosensitive member was prepared and evaluated in the same manner as in Example 1 except that 10 parts of the compound of the structural formula (2) and 1 part of the compound of the structural formula (3) were used as the charge transport material for the charge transport layer. did.

(Example 5)
A radical having a monofunctional charge transport structure is replaced with the following monomer in place of the trifunctional or higher radical polymerizable monomer having no charge transport structure, which is contained in the coating liquid for the crosslinkable charge transport layer of Example 1. The polymerizable compound was exemplified as Compound No. 1. An electrophotographic photosensitive member was prepared and evaluated in the same manner as in Example 1 except that 138 and 10 parts were used. This cross-linked charge transport layer is referred to as Type II. Note that the resolution of the image forming apparatus was 1200 dpi.

[Coating liquid II for cross-linked charge transport layer]
Trifunctional or higher functional radical polymerizable monomer having no charge transporting structure 10 parts pentaerythritol tetraacrylate {(SR-295, manufactured by Kayaku Sartomer)
Molecular weight: 352, number of functional groups: 4 functions, molecular weight / number of functional groups = 88}
10 parts of a radically polymerizable compound having a monofunctional charge transporting structure (Exemplary Compound No. 138)
Photopolymerization initiator 1 part {1-hydroxy-cyclohexyl-phenyl-ketone (Irgacure 184, manufactured by Ciba Specialty Chemicals)}
Tetrahydrofuran 100 parts

(Example 6)
A photoconductor was prepared and evaluated in the same manner as in Example 2 except that the coating solution I for the crosslinkable charge transport layer was changed to II. Note that the resolution of the image forming apparatus was 1200 dpi.

(Example 7)
A photoconductor was prepared and evaluated in the same manner as in Example 3 except that the coating solution I for the crosslinkable charge transport layer was changed to II. Note that the resolution of the image forming apparatus was 1200 dpi.

(Example 8)
A photoconductor was prepared and evaluated in the same manner as in Example 4 except that the coating solution I for the crosslinkable charge transport layer was changed to II. Note that the resolution of the image forming apparatus was 1200 dpi.

Example 9
The film thickness of the charge transport layer of Example 1 was 24 μm, and the trifunctional or higher functional radical polymerizable monomer having no charge transport structure contained in the coating liquid for the crosslinkable charge transport layer was replaced with the following monomers: An electrophotographic photoreceptor was prepared and evaluated in the same manner as in Example 1 except that the photopolymerization initiator was replaced with 1 part of the following compound and the film thickness of the cross-linked charge transport layer was 1.0 μm. This cross-linked charge transport layer is referred to as Type III.

[Coating Liquid III for Crosslinkable Charge Transport Layer III]
Trifunctional or more radical polymerizable monomer having no charge transport structure 10 parts {Caprolactone-modified dipentaerythritol hexaacrylate (KAYARAD DPCA-60, manufactured by Nippon Kayaku Co., Ltd.)
Molecular weight: 1263, number of functional groups: 6 functions, molecular weight / number of functional groups = 211}
10 parts of a radically polymerizable compound having a monofunctional charge transporting structure (Exemplary Compound No. 54)
Photopolymerization initiator 1 part {2,2-dimethoxy-1,2-diphenylethane-1-one (Irgacure 651, manufactured by Ciba Specialty Chemicals)}

(Example 10)
Example 2 is the same as Example 2 except that the charge transport layer thickness is 18 μm, the crosslinkable charge transport layer coating liquid I is replaced with III, and the crosslinkable charge transport layer thickness is 2.0 μm. Thus, an electrophotographic photoreceptor was prepared and evaluated.

(Example 11)
Example 3 is the same as Example 3 except that the film thickness of the charge transport layer is 17 μm, the coating liquid I for the crosslinkable charge transport layer is replaced with III, and the film thickness of the crosslinkable charge transport layer is 8.0 μm. Thus, an electrophotographic photoreceptor was prepared and evaluated. Note that the resolution of the image forming apparatus was 1200 dpi.

(Example 12)
Example 4 is the same as Example 4 except that the film thickness of the charge transport layer in Example 4 is 15 μm, the coating liquid I for the crosslinkable charge transport layer is replaced with III, and the film thickness of the crosslinkable charge transport layer is 10.0 μm. Similarly, an electrophotographic photoreceptor was prepared and evaluated. Note that the resolution of the image forming apparatus was 1200 dpi.

(Comparative Example 1)
An aluminum cylinder having a diameter of 30 mm and a length of 260 mm was used as a support.
A coating solution composed of the following materials was applied on the support by a dipping method, thermally cured at 140 ° C. for 30 minutes, and dried to form a conductive layer having a thickness of 15 μm.
Conductive pigment: SnO ₂ coated barium sulfate 10 parts Resistance adjusting pigment: Titanium oxide 2 parts Binder resin: Phenol resin 6 parts Leveling material: Silicone oil 0.001 part Solvent: Methanol, methoxypropanol 0.2 / 0.8 20 parts Next, a solution prepared by dissolving 3 parts of N-methoxymethylated nylon and 3 parts of copolymer nylon in a mixed solvent of 65 parts of methanol / 30 parts of n-butanol was applied by an immersion method and dried. An intermediate layer having a thickness of 0.5 μm was formed.

Next, the charge generation layer dispersion of Example 1 was applied by a dipping method and dried to form a charge generation layer having a thickness of 0.2 μm.
Next, 8 parts of the compound of the structural formula (2) of Example 1, 2 parts of the compound of the structural formula (3), and 12 parts of the polycarbonate Z resin (weight average molecular weight: 100,000) were mixed with 60 parts of monochlorobenzene / 40 parts of dichloromethane. Dissolved in the mixed solvent. This paint was applied by a dipping method and dried at 110 ° C. for 2 hours to form a charge transport layer having a film thickness of 25 μm. A photoconductor was obtained and evaluated in the same manner as in Example 1.

(Comparative Example 2)
An electrophotographic photoreceptor was prepared and evaluated in the same manner as in Comparative Example 1 except that the thickness of the charge transport layer was 19 μm.

(Comparative Example 3)
An electrophotographic photoreceptor was prepared and evaluated in the same manner as in Comparative Example 1 except that 5 parts of the compound of the structural formula (2) and 1 part of the compound of the structural formula (3) were used as the charge transport material for the charge transport layer. did.

(Comparative Example 4)
An electrophotographic photoreceptor was prepared and evaluated in the same manner as in Comparative Example 1 except that 10 parts of the compound of the structural formula (2) and 1 part of the compound of the structural formula (3) were used as the charge transport material for the charge transport layer. did.

(Comparative Example 5)
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that 10 parts of unsubstituted triphenylamine was used in place of the compounds of the structural formulas (2) and (3) as the charge transport material for the charge transport layer. And evaluated. Note that the resolution of the image forming apparatus was 1200 dpi.

(Comparative Example 6)
An electrophotographic photoreceptor was prepared and evaluated in the same manner as in Comparative Example 1 except that the compound of the structural formula (3) was used as the charge transport material for the charge transport layer.

(Reference Example 1)
An electrophotographic photosensitive member was produced and evaluated in the same manner as in Example 1 except that an exposure unit having one laser beam was used. However, the rotational speed of the polygon mirror needs to be doubled as compared with other examples employing a multi-beam type exposure means having two laser beams.

Table 4 shows the results of the above Examples, Comparative Examples, and Reference Examples.

It is sectional drawing of an example of the electrophotographic photosensitive member used for this invention. It is sectional drawing of the other example of the electrophotographic photosensitive member used for this invention. 1 is a configuration example of an electrophotographic apparatus of the present invention. It is a structural example of the process cartridge of this invention. It is an example of schematic structure of the exposure means of a multi-beam system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Charging means 2 Electrophotographic photoreceptor 15 Image exposure means 16 Developing means 17 Paper feed roller and paper feed guide 18 Transfer means 19 Cleaning means 19-1 Cleaning blade 30 Semiconductor laser diode array 31 Cylinder lens 32 Rotating polygon mirror 33 fθ lens 34 Toroidal lens 35 Collimating lens 36 Photosensitive drum 37 Photodetector

Claims (8)

An electrophotographic photosensitive member provided with a photosensitive layer comprising at least a charge generating layer, a charge transporting layer, and a cross-linked charge transporting layer on a support, a charging means for charging the electrophotographic photosensitive member, and a plurality of laser beams A multi-beam exposure means for forming an electrostatic latent image on the electrophotographic photosensitive member, a developing means for developing the electrophotographic photosensitive member on which the electrostatic latent image is formed with toner, and the electrophotographic photosensitive member An electrophotographic apparatus that includes a transfer unit that transfers the toner image on the transfer body to the transfer body, and that does not include a static elimination unit that uniformly neutralizes the electrostatic latent image on the electrophotographic photosensitive member prior to the charging unit;
The cross-linked charge transport layer of the electrophotographic photoreceptor was formed from a cured product of at least a trifunctional or higher functional radical polymerizable monomer having no charge transport structure and a radical polymerizable compound having a monofunctional charge transport structure . ones, and the electrophotographic apparatus, wherein the charge mobility of the photosensitive layer is ^{5.0 × 10 -7 ~2.0 × 10 -5} cm 2 / V · s. 2. The electrophotographic apparatus according to claim 1, wherein the electric field strength of the electrophotographic photosensitive member is 3.5 × 10 ⁵ V / cm or less. 3. The electrophotographic apparatus according to claim 1, wherein the image resolution is 1200 dpi or more. 4. The electrophotographic apparatus according to claim 1, wherein a film thickness of the cross-linked charge transport layer is 1 μm or more and 10 μm or less. The electrophotographic apparatus according to claim 4, wherein the thickness of the cross-linked charge transport layer is 2 μm or more and 8 μm or less. The radical polymerizable functional group of the tri- or higher functional radical polymerizable monomer having no charge transport structure and the radical polymerizable compound having a monofunctional charge transport structure used in the cross-linked charge transport layer is an acryloyloxy group and / or The electrophotographic apparatus according to claim 1, wherein the electrophotographic apparatus is a methacryloyloxy group. In the electrophotographic apparatus, at least one means selected from an electrophotographic photosensitive member, a charging means, an exposure means, a developing means, and a cleaning means is integrally supported, and an electrophotographic process cartridge that is detachable from the main body of the electrophotographic apparatus is provided. 2. The apparatus according to claim 1, wherein
The electrophotographic apparatus according to claim 1. 8. The electrophotographic apparatus according to claim 7, wherein at least one means selected from the group consisting of an electrophotographic photosensitive member, a charging means, a developing means, and a cleaning means is integrally supported and is detachable from the main body of the electrophotographic apparatus. A process cartridge for an electrophotographic apparatus.

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