JP2013011885A - Electrophotographic photoreceptor, process cartridge, electrophotographic apparatus and laminated film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor that reduces the friction of a photoreceptor and suppresses damage to a contact member.SOLUTION: In an electrophotographic photoreceptor, the surface layer of the electrophotographic photoreceptor contains a plurality of titanium oxide particles each of which has six extension portions extending radially to be a star-shaped hexagon. The number average particle diameter of the titanium oxide particles is 0.1 μm or more and 1.0 μm or less.

Description

  The present invention relates to an electrophotographic photosensitive member, a process cartridge, an electrophotographic apparatus, and a laminated film.

  In an electrophotographic photosensitive member (organic electrophotographic photosensitive member) containing an organic photoconductive substance, a contact member (such as a cleaning blade) is in contact with the surface of the electrophotographic photosensitive member. Therefore, the electrophotographic photosensitive member is required to reduce the occurrence of image deterioration due to contact stress with these contact members and the like, and is required to effectively reduce the frictional force on the surface of the electrophotographic photosensitive member. In particular, as the durability of electrophotographic photosensitive members has improved in recent years, resins with high wear resistance have been used for electrophotographic photosensitive members, and it is required to further reduce the frictional force between the photosensitive member and the contact member. It has been.

  As a method for reducing the frictional force of the electrophotographic photosensitive member, there is a method in which fine particles having high lubricity are contained in the surface layer of the electrophotographic photosensitive member. Patent Document 1 proposes a method of reducing the frictional force between the photosensitive member and the contact member by incorporating lubricating fine particles in the protective layer of the electrophotographic photosensitive member.

  On the other hand, Patent Document 2 proposes a method for improving printing durability by having a layer containing fine particles having a tetrapot shape on a substrate as a printing plate material.

JP-A-1-205171 JP 2004-237484 A

  However, as a result of the study by the present inventors, in the method described in Patent Document 1, since the shape of the fine particles is spherical, the fine particles are easily detached by contact with the contact member, and the frictional force between the photoconductor and the contact member. The effect of reducing is not sufficient. In addition, if the surface layer contains fine particles having a tetrapot shape described in Patent Document 2, the tip of the fine particles has a long and sharp shape, so that the contact member (such as a cleaning blade) is damaged. May end up.

  An object of the present invention is to provide an electrophotographic photosensitive member that reduces the frictional force of the photosensitive member and suppresses the occurrence of scratches on the contact member. Another object of the present invention is to provide a process cartridge and an electrophotographic apparatus having the electrophotographic photosensitive member. Another object of the present invention is to provide a laminated film that reduces the frictional force and suppresses the occurrence of scratches on the contact member.

  The above object is achieved by the present invention described below.

  The present invention relates to an electrophotographic photosensitive member having a support and a photosensitive layer formed on the support, wherein the surface layer of the electrophotographic photosensitive member has six extending portions extending radially. The present invention relates to an electrophotographic photosensitive member comprising rectangular titanium oxide particles, wherein the titanium oxide particles have a number average particle diameter of 0.1 μm or more and 1.0 μm or less.

  Further, the present invention integrally supports the electrophotographic photosensitive member and at least one means selected from the group consisting of a charging means, a developing means, a transfer means, and a cleaning means, and is detachable from the main body of the electrophotographic apparatus. The present invention relates to a process cartridge.

  The present invention also relates to an electrophotographic apparatus comprising the electrophotographic photosensitive member, a charging unit, an exposing unit, a developing unit, and a transfer unit.

  Further, the present invention provides a laminated film having a support, an intermediate layer formed on the support, and a charge transport layer having a charge transport material formed on the intermediate layer, wherein the charge transport layer is radially formed. The present invention relates to a laminated film comprising star-shaped hexagonal titanium oxide particles having six extended portions, wherein the number average particle diameter of the titanium oxide is 0.1 μm or more and 1.0 μm or less. .

  ADVANTAGE OF THE INVENTION According to this invention, while reducing the frictional force of an electrophotographic photoreceptor, the electrophotographic photoreceptor which can suppress generation | occurrence | production of the damage | wound to a contact member can be provided. In addition, according to the present invention, a process cartridge and an electrophotographic apparatus having the electrophotographic photosensitive member can be provided. Moreover, according to this invention, while reducing a frictional force, the laminated film which suppresses generation | occurrence | production of the damage | wound to a contact member can be provided.

It is a SEM (scanning electron microscope) image which shows an example of the titanium oxide particle of this invention. 1 is a diagram illustrating an example of a schematic configuration of an electrophotographic apparatus including a process cartridge having the electrophotographic photosensitive member of the present invention. It is a figure for demonstrating the layer structure of the electrophotographic photoreceptor of this invention. It is the SEM image which observed the surface of the surface layer of the electrophotographic photoreceptor of this invention. It is a SEM image of the zinc oxide particle of a tetrapot type shape. It is a figure which shows the method of cutting out the laminated film used in the Example of this invention.

  As described above, the electrophotographic photosensitive member of the present invention has a support and a photosensitive layer formed on the support, and the surface layer of the electrophotographic photosensitive member extends radially 6. It contains a star-shaped hexagonal titanium oxide particle having two extending portions, and the number average particle size of the titanium oxide particle is 0.1 μm or more and 1.0 μm or less.

  The present inventors presume the reason why the electrophotographic photosensitive member of the present invention can reduce the frictional force of the photosensitive member and suppress the occurrence of scratches on the contact member as follows. The electrophotographic photoreceptor of the present invention contains titanium oxide particles in the surface layer. The titanium oxide particles have a star-shaped hexagonal shape having six extending portions extending radially. Since the titanium oxide particles having a star-shaped hexagonal shape have six protrusions by the six apexes in the extending portion, the protrusions of many titanium oxide particles and the contact member can be in contact with each other. It is considered that the frictional force with the contact member can be reduced. In addition, since the titanium oxide particles having a star-shaped hexagonal shape are less likely to be detached by contact with the contact member, the effect of reducing the frictional force of the photosensitive member can be maintained more than the spherical particles. It is considered possible.

  Furthermore, since the titanium oxide particles have a star-shaped hexagonal shape and the number average particle size is relatively small as 0.1 μm or more and 1.0 μm or less, the protrusions do not become too long and contact with the photoreceptor. The contact with the member can suppress the occurrence of scratches on the contact member.

  For these reasons, it is presumed that the present invention has an effect of reducing the frictional force of the photoreceptor and suppressing the occurrence of scratches on the contact member.

  On the other hand, the tetrapot type particles described in JP-A No. 2004-237484 have a large average particle diameter, and sharp and long protrusions are easy to contact the contact member, so that the contact member (cleaning blade or the like) is damaged. May end up.

  The electrophotographic photoreceptor of the present invention is an electrophotographic photoreceptor having a support and a photosensitive layer provided on the support.

  In the present invention, the photosensitive layer is separated into a single layer type photosensitive layer containing a charge transport material and a charge generation material in the same layer, a charge generation layer containing a charge generation material, and a charge transport layer containing a charge transport material. And a laminated (functional separation type) photosensitive layer. The electrophotographic photosensitive member of the present invention is preferably a laminated photosensitive layer from the viewpoint of electrophotographic characteristics. Further, the charge generation layer and the charge transport layer itself can each have a laminated structure.

  An outline of a preferred structure of the electrophotographic photosensitive member in the present invention is shown in FIG. In the electrophotographic photoreceptor shown in FIG. 3, a conductive layer 22 is laminated on a support 21, an intermediate layer 23 is formed on the conductive layer, a charge generation layer 24 is formed on the intermediate layer, and a charge transport layer 25 is laminated on the charge generation layer. ing. Moreover, you may provide a protective layer on a charge transport layer as needed. The charge transport layer may have a laminated structure.

  The surface layer of the electrophotographic photosensitive member of the present invention is such that when the charge transport layer is the outermost surface, the charge transport layer is the surface layer, and when the protective layer is provided on the charge transport layer, the protective layer is It is a surface layer.

  The titanium oxide particles of the present invention have a shape as shown in the SEM image of the titanium oxide particles in FIG. The titanium oxide particles shown in FIG. 1 have six extending portions, and these six extending portions extend radially from each other at an equal interval, and as a whole, a star-shaped hexagonal shape (hexagonal star shape). It can also be said.) Further, the extending portion has a ridge at a substantially central portion in the length direction.

  The number average particle diameter of the titanium oxide particles is preferably 0.1 μm or more and 1.0 μm or less. If it is larger than 1.0 μm, the star-shaped hexagonal protrusion becomes long and the contact member is likely to be damaged. If it is less than 0.1 μm, the effect of reducing the frictional force of the photoreceptor may not be sufficient.

  In the present invention, the number average particle diameter of the titanium oxide particles can be determined using the following method. Measurement is performed using titanium oxide particles obtained by dissolving the surface layer with a solvent (solvent capable of dissolving the surface layer: tetrahydrofuran, etc.) from the produced photoreceptor. Using SEM, the particle diameters of 50 arbitrarily selected titanium oxide particles were measured and averaged to determine the number average particle diameter. As for the particle size of the titanium oxide, the maximum particle size among the distances between the six apexes of the star-shaped hexagonal shape was used as the particle size.

  The content of the titanium oxide particles is 0.1% by volume or more and 10% by volume or less in an environment of 27 ° C. and 1 atm with respect to the total mass of the surface layer. It is preferable because it is excellent. Furthermore, it is more preferable in it being 0.1 volume% or more and 5 volume% or less. If the volume is more than 10% by volume, the influence of light scattering increases, so that the electrophotographic characteristics may not be sufficient.

  The titanium oxide particles of the present invention can be produced by the method described in JP 2006-076798.

  In the electrophotographic photoreceptor of the present invention, the resin used for the surface layer includes acrylic resin, acrylonitrile resin, allyl resin, alkyd resin, epoxy resin, silicone resin, nylon, phenol resin, phenoxy resin, butyral resin, polyacrylamide resin. , Polyacetal resin, polyamideimide resin, polyamide resin, polyallyl ether resin, polyarylate resin, polyimide resin, polyurethane resin, polyester resin, polyethylene resin, polycarbonate resin, polystyrene resin, polystyrene resin, polysulfone resin, polyvinyl butyral resin, polyphenylene oxide Examples thereof include resins, polybutadiene resins, polypropylene resins, methacryl resins, urea resins, vinyl chloride resins, and vinyl acetate resins. These can be used singly or in combination of two or more as a mixture or copolymer. In particular, polyarylate resin, polycarbonate resin and the like are preferable. This is because the balance between the hardness of the polyarylate resin and polycarbonate resin and the hardness of the titanium oxide particles is balanced, making it difficult for the particles to be detached due to contact with the contact member, and an excellent effect of reducing the frictional force of the photoreceptor. can get.

  In the present invention, the weight average molecular weight of the resin used for the surface layer is preferably 10,000 or more and 200,000 or less from the viewpoint of mechanical strength. In particular, the polycarbonate resin is preferably 10,000 to 60,000, and the polyarylate resin is preferably 80,000 to 200,000. In the present invention, the weight average molecular weight of the resin is a polystyrene equivalent weight average molecular weight measured by a method described in JP-A-2009-104145 according to a conventional method.

  Next, the configuration of the electrophotographic photosensitive member of the present invention will be described.

  The electrophotographic photoreceptor of the present invention is an electrophotographic photoreceptor having a support and a photosensitive layer provided on the support.

[Conductive support]
The support used in the electrophotographic photoreceptor of the present invention is preferably a conductive one (conductive support), and examples thereof include aluminum, an aluminum alloy, and stainless steel. In the case of a support made of aluminum or an aluminum alloy, an ED tube, an EI tube, or a support obtained by cutting, electrolytic composite polishing, wet or dry honing treatment of these can also be used. Moreover, what formed the thin film of electroconductive materials, such as aluminum, an aluminum alloy, or an indium oxide tin oxide alloy, on the metal support body and the resin support body is also mentioned. The surface of the support may be subjected to cutting treatment, roughening treatment, alumite treatment, or the like.

  In addition, a support in which conductive particles such as carbon black, tin oxide particles, titanium oxide particles, and silver particles are impregnated in a resin, or a plastic having a conductive resin can also be used.

  Between the support and the photosensitive layer (charge generation layer, charge transport layer) or an intermediate layer described later, there is a conductive layer for the purpose of preventing interference fringes due to scattering of laser light or the like and covering the scratches on the support. It may be provided.

  In the electrophotographic photosensitive member of the present invention, a conductive layer having conductive particles and a resin may be provided on the support. The conductive layer is a layer formed using a conductive layer coating liquid in which conductive particles are dispersed in a resin. Examples of the conductive particles include carbon black, acetylene black, metal powders such as aluminum, nickel, iron, nichrome, copper, zinc, and silver, and metal oxide powders such as conductive tin oxide and ITO.

  Examples of the solvent for the conductive layer coating solution include ether solvents, alcohol solvents, ketone solvents, and aromatic hydrocarbon solvents. The thickness of the conductive layer is preferably 0.2 μm or more and 40 μm or less, and more preferably 1 μm or more and 35 μm or less. Further, it is more preferably 5 μm or more and 30 μm or less.

  In the electrophotographic photosensitive member of the present invention, an intermediate layer may be provided between the support or conductive layer and the charge generation layer.

  The intermediate layer can be formed by applying a coating liquid for intermediate layer containing a resin on a support or a conductive layer, and drying or curing it.

  Examples of the resin used for the intermediate layer include polyacrylic acids, methylcellulose, ethylcellulose, polyamide resin, polyolefin resin, polyimide resin, polyamideimide resin, polyamic acid, melamine resin, epoxy resin, and polyurethane resin. The resin used for the intermediate layer is preferably a thermoplastic resin, and specifically, a thermoplastic polyamide resin is preferable. The polyamide resin is preferably a low crystalline or non-crystalline copolymer nylon that can be applied in a solution state.

  The thickness of the intermediate layer is preferably 0.05 μm or more and 40 μm or less, and more preferably 0.1 μm or more and 30 μm or less. Further, the intermediate layer may contain semiconductive particles, an electron transporting material, or an electron accepting material.

(Charge generation layer)
In the electrophotographic photoreceptor of the present invention, a charge generation layer is provided on the support, the conductive layer or the intermediate layer.

  Examples of the charge generating material used in the electrophotographic photoreceptor of the present invention include azo pigments, phthalocyanine pigments, indigo pigments and perylene pigments. These charge generation materials may be used alone or in combination of two or more. Among these, oxytitanium phthalocyanine, hydroxygallium phthalocyanine, chlorogallium phthalocyanine and the like are particularly preferable because of high sensitivity.

  Examples of the resin used for the charge generation layer include polycarbonate resin, polyester resin, butyral resin, polyvinyl acetal resin, acrylic resin, vinyl acetate resin, and urea resin. Among these, a butyral resin is particularly preferable. These resins can be used alone, in combination, or as a copolymer.

  The charge generation layer can be formed by applying a charge generation layer coating solution obtained by dispersing a charge generation material together with a resin and a solvent and drying the coating solution. The charge generation layer may be a vapor generation film of a charge generation material.

  Examples of the dispersion method include a method using a homogenizer, an ultrasonic wave, a ball mill, a sand mill, an attritor, and a roll mill.

  The ratio of the charge generating material to the resin is preferably from 0.1 to 10 parts by weight, more preferably from 0.25 to 4 parts by weight, based on 1 part by weight of the resin.

  Examples of the solvent used in the charge generation layer coating solution include alcohol solvents, sulfoxide solvents, ketone solvents, ether solvents, ester solvents, and aromatic hydrocarbon solvents.

  The thickness of the charge generation layer is preferably from 0.01 μm to 5 μm, and more preferably from 0.1 μm to 2 μm. In addition, various sensitizers, antioxidants, ultraviolet absorbers, plasticizers, and the like can be added to the charge generation layer as necessary. In addition, in order to prevent the flow of charges in the charge generation layer from stagnation, the charge generation layer may contain an electron transport material or an electron accepting material.

(Charge transport layer)
In the electrophotographic photoreceptor of the present invention, a charge transport layer is provided on the charge generation layer.

  The charge transport layer can be formed by applying a charge transport layer coating solution obtained by dispersing a charge transport material together with a resin and a solvent, and drying it.

  In the present invention, when the charge transport layer is a surface layer, the charge transport material, the titanium oxide particles and the resin are contained. The resin used for the charge transport layer includes the resin used for the surface layer.

  Examples of the charge transport material used in the electrophotographic photoreceptor of the present invention include triarylamine compounds, hydrazone compounds, styryl compounds, stilbene compounds, pyrazoline compounds, oxazole compounds, thiazole compounds, triallylmethane compounds and the like. These charge transport materials may be used alone or in combination of two or more.

  Examples of the dispersing method include a method using a homogenizer, an ultrasonic disperser, a ball mill, a sand mill, a roll mill, and an attritor.

  The ratio of the charge transport material to the binder resin is preferably 0.5 parts by mass or more and 2 parts by mass or less of the electron transport material with respect to 1 part by mass of the binder resin.

  Examples of the solvent used for the charge transport layer coating solution include ketone solvents, ester solvents, aromatic hydrocarbon solvents, ether solvents, and halogenated hydrocarbon solvents. These solvents may be used alone or in combination of two or more.

  The thickness of the charge transport layer is preferably 5 to 30 μm, and more preferably 6 to 25 μm. In addition, an antioxidant, an ultraviolet absorber, a plasticizer, and the like can be added to the charge transport layer as necessary.

  In the electrophotographic photoreceptor of the present invention, a protective layer may be provided on the charge transport layer. In this case, the surface layer of the electrophotographic photosensitive member becomes a protective layer.

  The protective layer can be formed by applying a protective layer coating solution obtained by dispersing a binder resin and, if necessary, a charge transport material in a solvent, and drying the coating solution.

  As the charge transport material used in the protective layer, the same charge transport materials as those used in the charge transport layer described above can be used.

  Examples of the solvent used in the protective layer coating solution include alcohol solvents, sulfoxide solvents, Teton solvents, ether solvents, ester solvents, and aromatic hydrocarbon solvents.

  The thickness of the protective layer is preferably from 0.01 μm to 10 μm, and more preferably from 0.1 μm to 10 μm. Further, the protective layer may contain a leveling agent, a dispersant, an antioxidant, an ultraviolet absorber, a plasticizer, and the like as necessary.

  When applying the coating solution for each of the above layers, a coating method such as a dip coating method (a dip coating method), a spray coating method, a spinner coating method, a roller coating method, a Meyer bar coating method, a blade coating method, or the like can be used. .

[Electrophotographic equipment]
FIG. 2 shows an example of a schematic configuration of an electrophotographic apparatus provided with a process cartridge having the electrophotographic photosensitive member of the present invention.

  In FIG. 2, reference numeral 1 denotes a cylindrical electrophotographic photosensitive member, which is rotationally driven at a predetermined peripheral speed in the direction of an arrow about an axis 2. The surface of the electrophotographic photosensitive member 1 that is driven to rotate is uniformly charged to a predetermined negative potential by a charging unit (primary charging unit: charging roller or the like) 3 during the rotation process. Next, exposure light (image exposure light) 4 modulated in intensity corresponding to a time-series electric digital image signal of target image information output from exposure means (not shown) such as slit exposure or laser beam scanning exposure is received. . In this way, electrostatic latent images corresponding to the target image are sequentially formed on the surface of the electrophotographic photosensitive member 1.

  The electrostatic latent image formed on the surface of the electrophotographic photoreceptor 1 is developed by reversal development with toner contained in the developer of the developing means 5 to become a toner image. Next, the toner image formed and supported on the surface of the electrophotographic photosensitive member 1 is sequentially transferred onto a transfer material (such as paper) P by a transfer bias from a transfer unit (such as a transfer roller) 6. The transfer material P is taken out from the transfer material supply means (not shown) in synchronization with the rotation of the electrophotographic photosensitive member 1 and fed between the electrophotographic photosensitive member 1 and the transfer means 6 (contact portion). Is done. Further, a bias voltage having a polarity opposite to the charge held in the toner is applied to the transfer means 6 from a bias power source (not shown).

  The transfer material P that has received the transfer of the toner image is separated from the surface of the electrophotographic photosensitive member 1 and is carried into the fixing means 8 where the toner image is fixed and processed as an image formed product (print, copy) outside the apparatus. It is conveyed to.

  The surface of the electrophotographic photosensitive member 1 after the transfer of the toner image is cleaned by receiving a transfer residual developer (transfer residual toner) by a cleaning means (cleaning blade or the like) 7. Next, after being subjected to charge removal processing by pre-exposure light (not shown) from pre-exposure means (not shown), it is repeatedly used for image formation. As shown in FIG. 2, when the charging unit 3 is a contact charging unit using a charging roller or the like, pre-exposure is not necessarily required.

  In the present invention, a plurality of components such as the electrophotographic photosensitive member 1, the charging unit 3, the developing unit 5, the transfer unit 6 and the cleaning unit 7 are selected and stored in a container. As a single unit. The process cartridge may be configured to be detachable from an electrophotographic apparatus main body such as a copying machine or a laser beam printer. In FIG. 2, the electrophotographic photosensitive member 1, the charging unit 3, the developing unit 5, and the cleaning unit 7 are integrally supported to form a cartridge, and electrophotography is performed using a guide unit 10 such as a rail of the electrophotographic apparatus main body. The process cartridge 9 is detachable from the apparatus main body.

  Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples. However, the present invention is not limited to the following examples. In the examples, “part” means “part by mass”.

Example 1
First, an aluminum sheet having a short side of 12 cm, a long side of 24 cm, and a thickness of 0.05 cm was prepared and used as a support.

  Next, 8 parts of copolymer nylon resin (trade name: Amilan CM8000, manufactured by Toray Industries, Inc.) and 24 parts of N-methoxymethylated nylon (trade name: Toresin EF-30T, manufactured by Teikoku Chemical Industry Co., Ltd.) Then, an intermediate layer coating solution was prepared by dissolving in a mixed solvent of 614 parts of methanol and 155 parts of n-butanol. This intermediate layer coating solution was applied onto the aluminum sheet with a Mayer bar apparatus (# 12) and dried at 90 ° C. for 10 minutes to form an intermediate layer having a thickness of 1 μm.

  Next, 20 parts of hexagonal titanium oxide particles (trade name: ST-K4, manufactured by Sumitomo Osaka Cement Co., Ltd.) as shown in FIG. 1 are mixed with 80 parts of tetrahydrofuran, and glass beads with a diameter of 1 mm are mixed. The mixture was dispersed for 2 hours using the paint shaker (Toyo Seiki Seisakusho). After dispersion, the dispersion was filtered with nylon mesh # 100 (manufactured by Tokyo Screen Co., Ltd.), and the filtrate was used as a titanium oxide particle dispersion. On the other hand, a polycarbonate resin having a repeating structural unit represented by the following structural formula (A) (trade name: Iupilon Z400, manufactured by Mitsubishi Gas Chemical Co., Ltd., weight average molecular weight 39,000), 100 parts, 90 parts of the compound (charge transport material) and 572 parts of toluene were mixed and dissolved to prepare a charge transport material solution. The number average particle diameter of the titanium oxide particles was 0.5 μm.

Next, 0.33 parts of the titanium oxide particle dispersion and 80.05 parts of the charge transport material solution are mixed with tetrahydrofuran so that the solid content concentration is 20% by mass, and a paint shaker using glass beads having a diameter of 1 mm. For 1 hour. After dispersion, this dispersion was filtered with nylon mesh # 100 (manufactured by Tokyo Screen Co., Ltd.), and the filtrate was used as a coating solution for a charge transport layer. This charge transport layer coating solution was applied onto the intermediate layer with a Mayer bar apparatus (# 60) and dried at 120 ° C. for 1 hour to form a charge transport layer having a thickness of about 20 μm. The content of the titanium oxide particles in the formed charge transport layer is 0.1% by volume (with respect to the total mass of the charge transport layer) at 27 ° C. and 1 atmosphere, with respect to the total volume of the charge transport layer. 0.3 mass%). The density of titanium oxide is 3.9 g / cm ³ and the density of the charge transport layer is 1.2 g / cm ³ . Thus, a laminated film (film) having a support (aluminum sheet), an intermediate layer, and a charge transport layer was produced.

(Examples 2 to 5)
In Example 1, a laminated film was produced in the same manner as in Example 1 except that the contents of the titanium oxide particle dispersion and the charge transport material solution in the charge transport layer coating solution were changed as shown in Table 1. .

(Example 6)
100.1 parts (weight average molecular weight 120,000) of a polyarylate resin having a repeating structural unit represented by the following structural formula (4), 90.06 parts of the compound of the above structural formula (3) (charge transport material), and A charge transport material solution was prepared by mixing and dissolving 570.24 parts of toluene. A laminated film was produced in the same manner as in Example 1 except that the contents of the charge transport material solution and the titanium oxide particle dispersion (fine particle dispersion) were changed as shown in Table 1. The weight average molecular weight of the polyarylate resin was measured by gel permeation chromatography (trade name: HLC-8120, manufactured by Tosoh Corporation) and calculated in terms of polystyrene. The ratio of isophthalic acid / terephthalic acid in the polyarylate resin is 1/1.

The content of the titanium oxide particles in the formed charge transport layer was 1% by volume (at 2 ° C. in an atmosphere of 27 ° C. and 1 atmosphere) with respect to the total volume of the charge transport layer (2% relative to the total mass of the charge transport layer) .6 mass%). The density of titanium oxide is 3.9 g / cm ³ and the density of the charge transport layer is 1.2 g / cm ³ .

(Example 7)
In Example 8, a laminated film was prepared in the same manner as in Example 8 except that the contents of the titanium oxide particle dispersion and the charge transport material solution in the charge transport layer coating solution were changed as shown in Table 1. .

(Comparative Example 1)
In Example 1, the titanium oxide particles were changed to silica particles having a diameter of 0.5 μm (trade name: High Presica FR, manufactured by Ube Nitto Kasei Co., Ltd.), and the silica particle dispersion (fine particle dispersion) in the charge transport layer coating solution was used. ), And the charge transport material solution content was changed as shown in Table 1, and a laminated film was prepared in the same manner as in Example 1. The content of the silica particles in the formed charge transport layer is 1% by volume (1.% relative to the total mass of the charge transport layer) at 27.degree. 9% by mass). The density of silica is 2.2 g / cm ³ and the density of the charge transport layer is 1.2 g / cm ³ .

(Comparative Examples 2 to 4)
In Comparative Example 1, a laminated film was produced in the same manner as in Comparative Example 1 except that the contents of the silica particle dispersion and the charge transport material solution in the charge transport layer coating solution were changed as shown in Table 1.

(Comparative Examples 5 and 6)
In Example 6, the titanium oxide particles were changed to silica particles having a number average particle size of 0.5 μm (trade name: High Presica FR, manufactured by Ube Nitto Kasei Co., Ltd.), and the silica particle dispersion (fine particles) in the charge transport layer coating solution A laminated film was prepared in the same manner as in Example 6 except that the content of the dispersion liquid) and the charge transport material solution was changed as shown in Table 1. The density of silica is 2.2 g / cm ³ and the density of the charge transport layer is 1.2 g / cm ³ .

(Comparative Examples 7 and 8)
In Example 1, the titanium oxide particles were changed to tetrapod-type zinc oxide particles (trade name: Panatetra WZ-05E1, manufactured by Panasonic Corporation) as shown in FIG. 5, and the tetrapot in the coating solution for the charge transport layer was used. A laminated film was produced in the same manner as in Example 1 except that the contents of the type zinc oxide particle dispersion and the charge transport material solution were changed as shown in Table 1. The density of the tetrapod-shaped zinc oxide is 5.78 g / cm ^3, the density of the charge transport layer is 1.2 g / cm ^3. The number average particle diameter of the tetrapod type zinc oxide particles is 10 μm.

(Comparative Example 9)
194 parts of tetrahydrofuran was mixed with 6 parts of titanium oxide particles (trade name: ST-K4, manufactured by Sumitomo Osaka Cement), and zirconia beads having a diameter of 30 μm (trade name: Niimi NZ beads 30, manufactured by Niimi Sangyo Co., Ltd.) were used. Dispersed for 4 hours in a paint shaker. After dispersion, the dispersion was filtered through a nylon micromesh, and the filtrate was filtered under reduced pressure through an omnipore membrane (manufactured by Nippon Millipore) having a diameter of 0.1 μm. This filtrate was concentrated with an evaporator to prepare a solid content of 5.0% by mass. Furthermore, zirconia beads were added to 20 parts of a 5.0% by mass filtrate, and the mixture was dispersed for 1 hour using a paint shaker. The dispersion was filtered to prepare a 5.0% by mass small diameter star-shaped titanium oxide particle dispersion. A laminated film was produced in the same manner as in Example 1 except that the contents of the small-diameter star-shaped titanium oxide particle dispersion and the charge transport material solution were changed as shown in Table 1. The density of titanium oxide is 3.9 g / cm ³ and the density of the charge transport layer is 1.2 g / cm ³ . The number average particle diameter of the small diameter star-shaped titanium oxide is 0.06 μm.

(Comparative Example 10)
A laminated film was produced in the same manner as in Example 1 except that the content of the charge transport material solution was changed as shown in Table 1 without using titanium oxide particles.

(Comparative Example 11)
A laminated film was produced in the same manner as in Example 6 except that the content of the charge transport material solution was changed as shown in Table 1 without using titanium oxide particles.

  About the evaluation method of the laminated film of Examples 1-7 and Comparative Examples 1-11, it is as follows. The evaluation results are shown in Table 2.

(Measurement of dynamic friction coefficient)
As shown in FIG. 7, the light gray portion of the laminated film having a short side of 12 cm and a long side of 24 cm produced in the examples and comparative examples was cut with a cutter, and this was used as a sample for friction test.

  The dynamic friction coefficient was measured using a wear friction tester (trade name: HEIDON Type 20, manufactured by Shinto Kagaku Co., Ltd.). Place the sample for friction test (laminate film) on the stage, and fix the periphery of the sample for friction test with tape and fix it. Urethane rubber with 2mm thickness, 10mm width and 9mm length (JIS-A hardness: 70 degrees) Were brought into contact with each other at an angle of 24 ° (0 ° when the urethane rubber and the film sample were in contact with each other in parallel) from the friction test sample plane. A vertical load of 30 g was applied to the urethane rubber, the stage was rotated, the force applied between the friction test sample and the urethane rubber was measured, and the dynamic friction coefficient was obtained under the two conditions 1 and 2. . In Condition 1, measurement was performed for 60 minutes under conditions of a urethane rubber rotation radius of 25 mm, a stage rotation speed of 114.7 (rpm), and a rotation speed of 300 mm / second, and a friction coefficient of 55 to 60 minutes was calculated. . In Condition 2, measurement was performed for 20 minutes under the conditions of a urethane rubber rotation radius of 25 mm, a stage rotation speed of 114.7 (rpm), and a rotation speed of 300 mm / second, and a friction coefficient of 3 minutes from 17 to 20 minutes was calculated. . The results are shown in Table 2.

(Observation of rubber contact surface)
The contact portion of the urethane rubber after the dynamic friction test was observed using a digital microscope KH-7700 manufactured by Hilox Japan. The state of the surface scratches was evaluated according to the following criteria, and the results obtained are shown in Table 2. In the present invention, ◯ is a level at which the effect of the present invention is obtained in the following evaluation criteria. On the other hand, Δ and × were judged as levels at which the effects of the present invention were not obtained. The results are shown in Table 2.

  ○: No scratch or chipping.

  Δ: There is no noticeable chipping, but there is a scratch.

  X: There are a crack and a chip.

(Example 21)
The laminated film of Example 2 was used as a friction test sample, the vertical load of urethane rubber was changed to 60 g, and the dynamic friction coefficient measurement conditions were changed as follows to measure the dynamic friction coefficient. The measurement was performed for 10 minutes under the conditions of a urethane rubber rotation radius of 25 mm, a stage rotation speed of 114.7 (rpm), and a rotation speed of 300 mm / sec, and a friction coefficient of 8 to 10 minutes was calculated. The results are shown in Table 3.

(Comparative Example 22)
The laminated film of Comparative Example 1 was used as a friction test sample, and the friction coefficient was measured under the same dynamic friction coefficient measurement conditions as in Example 21. The results are shown in Table 3.

(Comparative Example 23)
The laminated film of Comparative Example 7 was used as a friction test sample, and the friction coefficient was measured under the same dynamic friction coefficient measurement conditions as in Example 21. The results are shown in Table 3.

(Example 31)
In the same manner as in Example 1, an intermediate layer was formed on an aluminum sheet.

  Next, the Bragg angles (2θ ± 0.2 °) in CuKα characteristic X-ray diffraction are 7.5 °, 9.9 °, 16.3 °, 18.6 °, 25.1 ° and 28.3 °. 10 parts of a crystalline hydroxygallium phthalocyanine crystal (charge generation material) having a strong peak was prepared. To this, 5 parts of polyvinyl butyral resin (trade name: ESREC BX-1, manufactured by Sekisui Chemical Co., Ltd.) and 260 parts of cyclohexanone were added and dispersed for 1.5 hours in a sand mill using glass beads having a diameter of 1 mm. The glass beads were separated by mesh filtration, and 240 parts of ethyl acetate was added to prepare a charge generation layer coating solution. This charge generation layer coating solution was applied onto the intermediate layer with a Mayer bar # 8 and dried at 90 ° C. for 10 minutes to form a charge generation layer having a thickness of 0.2 μm.

  On the formed charge generation layer, a charge transport layer having a thickness of 20 μm was formed in the same manner as in Example 1 to produce a laminated film.

(Reference Example 1)
In Example 31, a laminated film was produced in the same manner as in Example 31 except that the charge transport layer did not contain titanium oxide particles.

  In the evaluation of Example 31 and Reference Example 1, the evaluation of the exposure property and the sensitivity of the electrophotographic photosensitive member were performed.

  The electrophotographic photosensitive member was taken out from the magenta process cartridge CC533A using a laser beam printer (trade name: Color LaserJetCP2025) manufactured by Hewlett-Packard. The central portion of the electrophotographic photosensitive member was rubbed with a sandpaper (# 400) to expose the aluminum surface (support surface, one turn at a width of 5 cm). A carbon paste was applied to the aluminum surface, a laminated film cut to a width of 5 cm and a length of 7.5 cm was wound, and the four sides (1 mm width) of the laminated film were attached and fixed with tetrafluoroethylene tape. The electrophotographic photosensitive member having the laminated film fixed thereto was attached to a magenta process cartridge CC533A, and the magenta process cartridge was attached to the apparatus.

(Evaluation of exposure)
For evaluation of the exposure property, the electrophotographic photosensitive member was rotated at 300 mm / second, and a DC voltage of -1.3 kV was applied by a charging roller mounted in the cartridge to charge the laminated film. Next, after irradiating with white light, a developing bias of −300 V was applied to stop the rotation of the electrophotographic photosensitive member. Similar to the evaluation of developability, using a Macbeth reflection densitometer, the image density difference between the white background portion (image density is 0.0) and the laminated film is measured, and judged according to the following evaluation criteria to evaluate the exposure property. did. Further, after charging the laminated film as described above, a developing bias of −300 V was applied without irradiating with white light, and rotation of the electrophotographic photosensitive member was stopped. Then, using a Macbeth reflection densitometer, the image density difference between the white background portion and the laminated film was measured. The results are shown in Table 4.

A: Image density difference is 1.20 or more B: Image density difference is 1.00 or more and less than 1.20 C: Image density difference is less than 1.00

  D: No toner adhesion.

(Evaluation of sensitivity)
The evaluation of the sensitivity was performed by measuring the produced laminated film using a direct voltage application type electrophotographic photosensitive member measuring apparatus using 10 cm ² of NESA glass. An applied voltage Va is applied to the laminated film so that the surface potential becomes −700 V. After 20 milliseconds when the surface potential of the laminated film becomes −700 V, light with an exposure wavelength of 778 nm is irradiated for 100 milliseconds, and 95 milliseconds. Later, the surface potential of the laminated film was measured. As the light source, a halogen lamp monochromatic with an interference filter having a wavelength of 778 nm was used. The photosensitivity (EΔ500V) was determined from the amount of light (cJ / m ² ) when the surface potential of the laminated film became −200V by exposure.

  From Table 4, the electrophotographic characteristics (exposure and sensitivity) of Example 31 are at the same level as in Reference Example 1. Therefore, the electrophotographic photosensitive member of the present invention is considered to reduce the frictional force, suppress the generation of scratches on the contact member, and satisfy the electrophotographic characteristics.

  By comparing the Examples and Comparative Examples 1 to 6, when the surface layer contains spherical silica particles, the shape of the silica particles is spherical, so that the silica particles are easily detached by contact with the contact member, The effect of reducing the frictional force is not sufficiently obtained.

  According to the comparison between Examples and Comparative Examples 7 and 8, when the surface layer contains tetrapot type zinc oxide particles, the average particle diameter of the zinc oxide particles is large and the tetrapot shape is so sharp and long. Since the protrusion easily comes into contact with the contact member, the contact member is likely to be damaged.

  As a result of comparison between Example and Comparative Example 9, if the average particle diameter of the star-shaped hexagonal titanium oxide particles is small, the effect of reducing the frictional force cannot be sufficiently obtained.

  As a result of comparison between Examples and Comparative Examples 10 and 11, the effect of reducing the frictional force cannot be obtained unless the surface layer contains star-shaped hexagonal titanium oxide particles.

(Example 32)
(Manufacture of electrophotographic photoreceptors)
An aluminum cylinder having a diameter of 24 mm and a length of 257 mm was used as a support.

Next, SnO ₂ coat-treated barium sulfate (conductive particles) 10 parts, titanium oxide (resistance control pigment) 2 parts, phenol resin 6 parts, silicone oil (leveling agent) 0.001 part and methanol 4 parts / methoxypropanol A conductive layer coating solution was prepared using 16 parts of a mixed solvent.

  The conductive layer coating solution was dip-coated on a support and heated at 140 ° C. for 30 minutes to form a conductive layer having a thickness of 15 μm.

  Next, the intermediate layer coating solution prepared in Example 1 was dip coated on the conductive layer and dried at 100 ° C. for 10 minutes to form an intermediate layer having a thickness of 0.7 μm.

  Next, strong peaks at 7.5 °, 9.9 °, 16.3 °, 18.6 °, 25.1 ° and 28.3 ° with a Bragg angle 2θ ± 0.2 ° in CuKα characteristic X-ray diffraction 10 parts of a crystalline form of hydroxygallium phthalocyanine (charge generating substance) having a hydrogen content is added to a solution of 250 parts of cyclohexanone and 5 parts of polyvinyl butyral resin (trade name: ESREC BX-1, manufactured by Sekisui Chemical Co., Ltd.). It was. This was dispersed for 1 hour in an atmosphere of 23 ± 3 ° C. by a sand mill apparatus using glass beads having a diameter of 1 mm. After dispersion, a coating solution for charge generation layer was prepared by adding 250 parts of ethyl acetate.

  This charge generation layer coating solution was dip-coated on the intermediate layer and dried at 100 ° C. for 10 minutes to form a charge generation layer having a thickness of 0.26 μm.

  Next, the coating liquid for charge transport layer prepared in Example 1 is put in a coating apparatus equipped with a device for circulating liquid, and is dip-coated on the charge generation layer while circulating the liquid. By drying for 1 hour, a charge transport layer was formed, and an electrophotographic photosensitive member was produced. The immersion conditions were adjusted so that the thickness of the charge transport layer after drying was 20 μm.

(Examples 33 to 38)
An electrophotographic photosensitive member was produced in the same manner as in Example 32 except that the charge transport layer coating solution was changed to the charge transport layer coating solution described in Examples 2 to 7 in Example 32.

(Image evaluation)
The produced electrophotographic photosensitive member was mounted on a laser beam printer (trade name: LBP-2510) manufactured by Canon Inc., image formation was performed, and the obtained image was evaluated. In the evaluation, the exposure amount (image exposure amount) of the laser light source of 780 nm was used by modifying so that the light amount on the surface of the electrophotographic photosensitive member was 0.3 μJ / cm ² . The evaluation was performed in an environment of a temperature of 23 ° C. and a humidity of 15%. As the image evaluation, a monochrome halftone image was output using A4 size plain paper, and the output image was visually evaluated according to the following criteria.

Rank A: A uniform image on the entire surface Rank B: Minor image unevenness in a small part Rank C: Evaluation results with image unevenness are shown in Table 5.

(Measurement of dynamic friction coefficient before and after paper passing)
The dynamic friction coefficient of the surface (circumferential surface) of the produced electrophotographic photosensitive member was measured using an abrasion friction tester (trade name: HEIDON Type 14FW, manufactured by Shinto Kagaku Co.). Install the fastener, place the electrophotographic photosensitive member and fix it with tape, and make urethane rubber (JIS-A hardness: 70 degrees) 2 mm thick, 10 mm wide and 9 mm long from the edge of the sample for friction test. It was made to contact the surface (circumferential surface) of the electrophotographic photosensitive member at an angle of 24 ° (the angle at which the urethane rubber and the stage were in parallel contact with each other was 0 °). A vertical load of 30 g was applied to the urethane rubber, the stage was moved 5 cm at a speed of 300 mm / sec, the force applied between the friction test sample and the urethane rubber was measured, and the dynamic friction coefficient was determined. Similarly, the coefficient of dynamic friction of the surface of the electrophotographic photosensitive member after the continuous passage of 5,000 sheets of the electrophotographic photosensitive member with a laser beam printer (trade name: LBP-2510) manufactured by Canon Inc. was measured. Evaluation was performed by calculating the specific friction coefficient of the surface of the electrophotographic photosensitive member after continuous 5,000 sheets passing as follows, assuming that the dynamic friction coefficient before passing is 1. Evaluation is performed according to the following criteria, and the obtained results are shown in Table 5. In the present invention, according to the following evaluation criteria, A and B are levels at which the effects of the present invention are obtained, and among them, A is judged to be an excellent level. On the other hand, C was judged to be a level where the effect of the present invention was not obtained.

Specific friction coefficient = (Dynamic friction coefficient of the surface of the electrophotographic photosensitive member after passing 5,000 sheets continuously) / (Dynamic friction coefficient of the surface of the electrophotographic photosensitive member before passing 5,000 sheets continuously)
A: Specific friction coefficient is less than 1.2 B: Specific friction coefficient is 1.2 or more and less than 1.4 C: Specific dynamic friction coefficient is 1.4 or more

DESCRIPTION OF SYMBOLS 1 Electrophotographic photoreceptor 2 Axis 3 Charging means 4 Exposure light (image exposure light)
DESCRIPTION OF SYMBOLS 5 Developing means 6 Transfer means 7 Cleaning means 8 Fixing means 9 Process cartridge 10 Guide means 11 Pre-exposure light P Transfer material 21 Support body 22 Conductive layer 23 Intermediate layer 24 Charge generation layer 25 Charge transport layer

Claims (6)

In an electrophotographic photosensitive member having a support and a photosensitive layer formed on the support,
The surface layer of the electrophotographic photosensitive member contains star-shaped hexagonal titanium oxide particles having six extending portions extending radially;
An electrophotographic photoreceptor, wherein the number average particle diameter of the titanium oxide particles is 0.1 μm or more and 1.0 μm or less.   2. The electrophotographic photosensitive member according to claim 1, wherein the content of the titanium oxide particles is 0.1% by volume or more and 10% by volume or less with respect to the total volume of the surface layer.   The electrophotographic photosensitive member according to claim 1, wherein the surface layer contains at least one of a polycarbonate resin and a polyarylate resin.   An electrophotographic photosensitive member according to any one of claims 1 to 3 and at least one means selected from the group consisting of a charging means, a developing means, a transfer means, and a cleaning means are integrally supported, and A process cartridge which is detachable from a photographic apparatus main body.   An electrophotographic apparatus comprising: the electrophotographic photosensitive member according to claim 1; a charging unit, an exposure unit, a developing unit, and a transfer unit. In a laminated film having a support, an intermediate layer formed on the support, and a charge transport layer having a charge transport material formed on the intermediate layer,
The charge transport layer contains star-shaped hexagonal titanium oxide particles having six extending portions extending radially,
A laminated film, wherein the titanium oxide has a number average particle size of 0.1 μm or more and 1.0 μm or less.