JP2005164936A - Electrophotographic photoreceptor, process cartridge and electrophotographic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor in which a photo-memory and a ghost liable to occur remarkably is suppressed, in an electrophotographic photoreceptor in which a polyarylate resin is used as a binder resin in a charge transport layer which is a surface layer and the thickness of the charge transport layer is made larger, and to provide a process cartridge with the electrophotographic photoreceptor and an electrophotographic apparatus. <P>SOLUTION: In the electrophotographic photoreceptor having a charge generating layer and a charge transport layer in this order on a substrate, wherein at least one of binder resins in the charge transport layer is a polyarylate resin and a thickness of the charge transport layer is ≥28 μm, the charge generating layer contains gallium phthalocyanine and the charge transport layer contains an antioxidant in an amount of 5-40 mass% of the total mass of the binder resins in the charge transport layer. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

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

  As an electrophotographic photosensitive member mounted in an electrophotographic image forming apparatus such as a copying machine or a laser printer, that is, an electrophotographic photosensitive member, because of its advantages such as high safety, suitable for mass production, and low cost. An organic electrophotographic photoreceptor using an organic photoconductive substance is often used.

  In an organic electrophotographic photoreceptor, charge generation ability and charge transport ability are expressed by different materials in order to increase sensitivity. Due to this functional separation, the range of choice of materials has expanded, and so far excellent materials have been developed. Numerous organic dyes and organic pigments have been developed as charge generation materials, but with the digitization of image formation, phthalocyanine pigments and azo pigments with high sensitivity in the infrared wavelength region of laser light sources and LED light sources are representative. It has been developed as a typical material.

  In addition, since electrical and mechanical external forces such as charging, exposure, development, transfer, and cleaning are applied to the surface of the electrophotographic photosensitive member, durability against them is required. In order to improve the durability, the photosensitive layer is mainly a laminated photosensitive layer in which a charge transport layer containing a charge transport material is provided as a surface layer on a charge generation layer containing a charge generation material.

  An organic electrophotographic photosensitive member using a soft material is inferior in durability to a mechanical external force, unlike an inorganic electrophotographic photosensitive member using an inorganic substance. Therefore, at present, development of a high-strength resin has been actively conducted as a binder resin used for a charge transport layer which is a surface layer of an electrophotographic photoreceptor. As a resin excellent in durability against mechanical external force, a polyarylate resin synthesized from bisphenol A and an aromatic dicarboxylic acid is known. In addition, polyarylate resins having various structures are also known (Patent Documents 1 to 3).

  Further, it is known that an electrophotographic photoreceptor is deteriorated by light such as a fluorescent lamp or exposure in an electrophotographic process. When an image is output using an electrophotographic photosensitive member exposed to light such as a fluorescent lamp, a potential difference is generated between the light-irradiated part and the non-irradiated part (called photo memory), and fog and image density A difference occurs.

  Therefore, the process cartridge is often provided with a shutter (called a drum shutter) so that the electrophotographic photosensitive member is not exposed to light.

  Also, in the exposure in the electrophotographic process, electric charge stays in the part irradiated with light and remains as a memory in the electrophotographic photosensitive member until the next rotation of the electrophotographic photosensitive member. A potential difference is generated between the unexposed portion and an inherent pattern may appear on the output image (referred to as a ghost) particularly when there is no pre-exposure process in the electrophotographic process.

  When the electrophotographic photosensitive member is used repeatedly, the memory phenomenon of photo memory and ghost is further deteriorated. In particular, in a long-life electrophotographic photoreceptor using a polyarylate resin as a binder resin in the charge transport layer which is a surface layer and having a thick charge transport layer (28 μm or more), initial and repeated When used, there is a problem that the occurrence of photo memory and ghost becomes remarkable.

In recent years, along with cost reduction, electrophotographic apparatuses and process cartridges in which a pre-exposure process is omitted or a drum shutter is omitted have been developed. Further, in order to cope with higher image quality and higher speed, improvement of image defects due to light deterioration of the above-described electrophotographic photosensitive member is required.
Japanese Patent Laid-Open No. 04-179961 JP 09-073183 A JP 2000-227668 A

  An object of the present invention is to use a photomemory or the like which is remarkably generated in an electrophotographic photoreceptor using a polyarylate resin as a binder resin in a charge transport layer which is a surface layer and having a thick charge transport layer. An object of the present invention is to provide an electrophotographic photosensitive member in which ghost is suppressed, a process cartridge and an electrophotographic apparatus having the electrophotographic photosensitive member.

The present invention is an electrophotographic photoreceptor having a charge generation layer and a charge transport layer in this order on a support, wherein at least one binder resin in the charge transport layer is a polyarylate resin, In the electrophotographic photosensitive member having a transport layer thickness of 28 μm or more,
The charge generation layer contains gallium phthalocyanine;
The electrophotographic photoreceptor, wherein the charge transport layer contains an antioxidant in an amount of 5% by weight to less than 40% by weight based on the total weight of the binder resin in the charge transport layer.

  The present invention also provides a process cartridge and an electrophotographic apparatus having the electrophotographic photosensitive member.

  According to the present invention, in an electrophotographic photoreceptor using a polyarylate resin as a binder resin in a charge transport layer that is a surface layer and having a thick charge transport layer, An electrophotographic photosensitive member in which ghost is suppressed, a process cartridge and an electrophotographic apparatus having the electrophotographic photosensitive member can be provided.

  Hereinafter, the present invention will be described in more detail.

  As a result of intensive studies by the present inventors, in an electrophotographic photosensitive member having a charge generation layer and a charge transport layer in this order on a support, the charge transport layer contains an antioxidant and a binder resin in the charge transport layer. It was found that the photo-memory and ghosting caused by light fatigue can be suppressed by containing 5% by mass or more and less than 40% by mass with respect to the total mass of the gallium phthalocyanine and the charge generation layer contains gallium phthalocyanine.

  The reason that antioxidants can suppress photomemory and ghost is thought to be that the antioxidants quickly return the charges accumulated in the charge transport layer to the ground state. Then it is unknown.

  Further, it has been found that by containing gallium phthalocyanine in the charge generation layer, the photomemory and ghost suppression effects by the antioxidant are more easily exhibited.

  In addition, when the charge transport layer contains a polyarylate resin as a binder resin and the charge transport layer has a thickness of 28 μm or more, the charge is easily accumulated as a memory in the charge transport layer. The invention works particularly effectively.

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

  As described above, the electrophotographic photoreceptor of the present invention is an electrophotographic photoreceptor having a charge generation layer and a charge transport layer in this order on a support, and is at least one binder resin in the charge transport layer. Is a polyarylate resin, and the electrophotographic photosensitive member has a thickness of the charge transport layer of 28 μm or more.

  As a support body, what is necessary is just to have electroconductivity, For example, metal support bodies, such as aluminum, aluminum alloy, and stainless steel, can be used. Moreover, the said metal support body and plastic support body which have the layer in which aluminum, aluminum alloy, the indium oxide tin oxide alloy etc. were formed into a film by vacuum deposition can also be used. It is also possible to use a support in which conductive particles such as carbon black, tin oxide particles, titanium oxide particles and silver particles are impregnated with plastic or paper together with an appropriate binder resin, or a plastic having a conductive binder resin. it can.

  A conductive layer may be provided between the support and the charge generation layer for the purpose of preventing interference fringes due to scattering of laser light or the like, and covering the scratches on the support. The conductive layer can be formed by dispersing conductive particles such as carbon black and metal particles in a binder resin. The film thickness of the conductive layer is preferably 0.5 to 25 μm. In order to prevent interference fringes, it is also effective to add silica particles.

  Further, in order to prevent interference fringes, the support surface may be subjected to a cutting treatment, a surface roughening treatment, an alumite treatment, or the like.

  Further, an intermediate layer having a barrier function or an adhesive function may be provided between the support or the conductive layer and the charge generation layer. The intermediate layer is formed for the purpose of improving the adhesion of the photosensitive layer, improving the coating property, improving the charge injection property from the support, and protecting the photosensitive layer from electrical breakdown. The intermediate layer can be formed using materials such as casein, polyvinyl alcohol, ethyl cellulose, ethylene-acrylic acid copolymer, polyamide, modified polyamide, polyurethane, gelatin, and aluminum oxide. The thickness of the intermediate layer is preferably 0.05 to 3 μm, and more preferably 0.3 to 1 μm.

  A charge generation layer is provided on the support, the conductive layer, or the intermediate layer.

  The charge generation material used in the charge generation layer of the electrophotographic photoreceptor of the present invention is gallium phthalocyanine. Among gallium phthalocyanines, hydroxygallium phthalocyanine and chlorogallium phthalocyanine are preferable, and have peaks at 7.4 ° ± 0.2 ° and 28.2 ° ± 0.2 ° of the Bragg angle 2θ in CuKα characteristic X-ray diffraction. Crystalline hydroxygallium phthalocyanine is more preferred. Further, hydroxygallium phthalocyanine and chlorogallium phthalocyanine preferably have a structure represented by the following formula.

（上記式中、ＸはＯＨまたＣｌを示す。）

(In the above formula, X represents OH or Cl.)

  In addition, other types of charge generating materials may be used in combination as long as the effects of the present invention are not impaired. Examples of other types of charge generating materials include phthalocyanine pigments other than gallium phthalocyanine, azo pigments such as monoazo, disazo, and trisazo, indigo pigments such as indigo and thioindigo, and perylenes such as perylene anhydride and perylene imide. Pigments, polycyclic quinone pigments such as anthraquinone and pyrenequinone, squarylium dyes, pyrylium salts and thiapyrylium salts, triphenylmethane dyes, inorganic substances such as selenium, selenium-tellurium, amorphous silicon, quinacridone pigments, Examples include azulenium salt pigments, cyanine dyes, xanthene dyes, quinoneimine dyes, styryl dyes, cadmium sulfide, and zinc oxide. However, it is preferable that gallium phthalocyanine is 50-100 mass% with respect to the total mass of all the charge generating substances.

  Examples of the binder resin used for the charge generation layer include polycarbonate resin, polyester resin, polyarylate resin, butyral resin, polystyrene resin, polyvinyl acetal resin, diallyl phthalate resin, acrylic resin, methacrylic resin, vinyl acetate resin, phenol resin, Examples thereof include silicone resins, polysulfone resins, styrene-butadiene copolymer resins, alkyd resins, epoxy resins, urea resins, vinyl chloride-vinyl acetate copolymer resins. These can be used singly or in combination of two or more as a mixture or copolymer.

  The solvent used in the coating solution for the charge generation layer is selected from the solubility and dispersion stability of the binder resin and charge generation material used, and the organic solvents include alcohols, sulfoxides, ketones, ethers, esters, aliphatic halogens. Hydrocarbons and aromatic compounds.

  The charge generation layer can be formed by applying and drying a charge generation layer coating solution obtained by dispersing a charge generation material together with a binder resin and a solvent. Examples of the dispersion method include a method using a homogenizer, an ultrasonic wave, a ball mill, a sand mill, an attritor, a roll mill and the like. The ratio between the charge generation material and the binder resin is preferably in the range of 10: 1 to 1: 5 (mass ratio), and more preferably in the range of 5: 1 to 1: 4 (mass ratio).

  In applying the charge generation layer coating solution, for example, a coating method such as 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.

  Moreover, it is preferable that the film thickness of a charge generation layer is 0.05-2 micrometers.

  In addition, various sensitizers, antioxidants, ultraviolet absorbers, plasticizers, and the like can be added to the charge generation layer as necessary.

  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.

  The binder resin used for the charge transport layer of the electrophotographic photoreceptor of the present invention is a polyarylate resin. The weight average molecular weight of the polyarylate resin is preferably 100,000 or more from the viewpoint of mechanical strength, and is preferably 250,000 or less from the viewpoint of productivity.

  Specific examples of the repeating structural unit possessed by the polyarylate resin used in the charge transport layer of the electrophotographic photoreceptor of the present invention are shown below, but the present invention is not limited thereto.

  Moreover, you may use together binder resin other than polyarylate resin as binder resin of an electric charge transport layer. Examples of the binder resin other than the polyarylate resin include acrylic resin, styrene resin, polyester resin, polycarbonate resin, polysulfone resin, polyphenylene oxide resin, epoxy resin, polyurethane resin, alkyd resin, and unsaturated resin. However, the polyarylate resin is preferably 70 to 100% by mass with respect to the total mass of all the binder resins in the charge transport layer.

  The charge transport layer can be formed by applying and drying a charge transport layer coating solution obtained by dissolving a charge transport material and a binder resin in a solvent. The ratio between the charge transport material and the binder resin is preferably in the range of 5: 1 to 1: 5 (mass ratio), and more preferably in the range of 3: 1 to 1: 3 (mass ratio).

  Solvents used in the charge transport layer coating solution include ketones such as acetone and methyl ethyl ketone, esters such as methyl acetate and ethyl acetate, aromatic hydrocarbons such as toluene and xylene, ethers such as tetrahydrofuran, chlorobenzene, chloroform, and carbon tetrachloride. A hydrocarbon substituted with a halogen atom such as is used.

  When applying the charge transport layer coating solution, for example, a coating method such as 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.

  The thickness of the charge transport layer of the electrophotographic photosensitive member of the present invention is 28 μm or more, but is preferably 40 μm or less from the viewpoint of electrophotographic characteristics and productivity.

  The charge transport layer of the electrophotographic photoreceptor of the present invention contains an antioxidant. The content of the antioxidant is 5% by mass or more and less than 40% by mass with respect to the total mass of the binder resin in the charge transport layer. In particular, it is preferably 10% by mass or more, and preferably 35% by mass or less. When the content of the antioxidant is less than 5% by mass, the effect of suppressing photo memory and ghost is not sufficiently exhibited. In addition, when the content of the antioxidant is 40% by mass or more, the effect obtained is the same as when the content is less than 40% by mass, while the charge transport layer machine, which is the surface layer of the electrophotographic photoreceptor, is used. The durability (wear resistance) against the external force will be reduced.

  Moreover, as an antioxidant contained in the charge transport layer, an antioxidant having a hindered phenol structure, an antioxidant having a benzotriazole structure, and an antioxidant containing a phosphorus atom are preferable.

  Specific examples of the antioxidant used in the charge transport layer of the electrophotographic photoreceptor of the present invention are shown below, but the present invention is not limited to these.

  Moreover, an ultraviolet absorber, a plasticizer, etc. can also be added to a charge transport layer as needed.

  In addition, the charge transport layer serving as the surface layer of the electrophotographic photosensitive member may contain a silicone-based comb-type graft polymer, a fluorine-based comb-type graft polymer, fluorine atom-containing resin particles, and a siloxane unit-containing resin.

  FIG. 1 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. 1, reference numeral 1 denotes a drum-shaped electrophotographic photosensitive member, which is driven to rotate about a shaft 2 in a direction indicated by an arrow at a predetermined peripheral speed.

  The peripheral surface of the electrophotographic photosensitive member 1 that is driven to rotate is uniformly charged to a predetermined positive or negative potential by a charging means (primary charging means) 3, and then exposure means such as slit exposure or laser beam scanning exposure ( It receives exposure light (image exposure light) 4 output from (not shown). In this way, electrostatic latent images corresponding to the target image are sequentially formed on the peripheral surface of the electrophotographic photosensitive member 1. The voltage applied to the charging unit 3 may be only a DC voltage or a DC voltage on which an AC voltage is superimposed.

  The electrostatic latent image formed on the peripheral surface of the electrophotographic photosensitive member 1 is developed with toner of the developing unit 5 to become a toner image. Next, the toner image formed and supported on the peripheral surface of the electrophotographic photosensitive member 1 is transferred from the transfer material supply unit (not shown) by the transfer bias from the transfer unit (transfer roller) 6 to the electrophotographic photosensitive member 1 and the transfer unit. 6 (contact portion) is sequentially transferred onto a transfer material (paper or the like) P taken out and fed in synchronization with the rotation of the electrophotographic photosensitive member 1.

  The transfer material P that has received the transfer of the toner image is separated from the peripheral surface of the electrophotographic photosensitive member 1 and is introduced into the fixing means 8 to undergo image fixing, and is printed out of the apparatus as an image formed product (print, copy). Out.

  The peripheral surface of the electrophotographic photosensitive member 1 after the toner image is transferred is cleaned by removing the transfer residual toner by a cleaning means (cleaning blade or the like) 7 and further pre-exposed light from a pre-exposure means (not shown). After being neutralized by (not shown), it is repeatedly used for image formation. As shown in FIG. 1, when the charging unit 3 is a contact charging unit using a charging roller or the like, pre-exposure is not necessarily required.

  Among the above-described 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, a plurality of components are housed in a container and integrally combined as a process cartridge. 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. 1, 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 the electrophotographic apparatus main body is mounted on the electrophotographic apparatus main body using a guide unit 10 such as a rail of the electrophotographic apparatus main body. The process cartridge 9 is detachable.

  FIG. 2 is also a diagram showing an example of a schematic configuration of an electrophotographic apparatus provided with a process cartridge having the electrophotographic photosensitive member of the present invention. The operation of the electrophotographic apparatus having the configuration shown in FIG. 2 is the same as that of the electrophotographic apparatus having the configuration shown in FIG. The electrophotographic apparatus having the configuration shown in FIG. 2 includes a first process cartridge 91 having an electrophotographic photosensitive member 1, a charging unit 3 and a cleaning unit 7, and a second process cartridge 92 having a developing unit 5.

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

(Synthesis Example 1) Synthesis of polyarylate resin As an example, polyarylate resin having a repeating structural unit represented by the above formula (PA-2) and a repeating structural unit represented by the above formula (PA-14) in a ratio of 1: 1. A synthesis example of

  After dissolving 0.3 mol of each bisphenol monomer derived from each formula, 0.012 mol of p- (t-butyl) phenol as a molecular weight regulator, and 65 g of sodium hydroxide in 2 liters of ion-exchanged water, Tributylbenzylammonium chloride as a phase transfer catalyst was added and dissolved (aqueous phase).

  Separately, 0.64 mol of a 1: 1 mixture of terephthalic acid chloride and isophthalic acid chloride was dissolved in 1 liter of dichloromethane (organic phase).

  Next, the reaction vessel was kept at 20 ° C., the organic phase was added to the aqueous phase under strong stirring, and interfacial polymerization was performed for 4 hours. Although the polymer formed in the organic phase is present, the organic phase was sufficiently washed with ion-exchanged water in order to prevent the catalyst from being mixed into the polymer.

  The organic phase was then dropped into methanol to reprecipitate and isolate the polymer.

  The obtained polymer (polyarylate resin) had a weight average molecular weight of 115,000.

  The weight average molecular weight (Mw) was measured using HLC-8120GPC (manufactured by Tosoh Corporation).

  The sample to be measured was put in THF and allowed to stand for several hours, and then sufficiently shaken and mixed well with THF (mixed until the sample was not united), and allowed to stand for 12 hours or more.

  Next, a sample processing filter (pore size: 0.5 μm, using Myshoori disk H-25-5 (trade name) manufactured by Tosoh Corporation) was used as a sample solution for GPC. The concentration of the resin component in the GPC sample solution was adjusted to 1 mg / ml.

  Next, the column for GPC was stabilized in a heat chamber at 40 ° C., THF was flowed through this column at a flow rate of 1 ml / min, and 10 μl of the GPC sample solution was injected to measure the weight average molecular weight. .

In measuring the weight average molecular weight, the molecular weight distribution of the sample to be measured was calculated from the relationship between the logarithmic value of the calibration curve prepared from several monodisperse polystyrene standard samples and the number of counts. As a standard polystyrene sample for preparing a calibration curve, ten samples having a molecular weight in the range of 10 ² to 10 ⁷ manufactured by Tosoh Corporation were used. An RI (refractive index) detector was used as the detector. In addition, TSKgel G2000H (H _XL ) manufactured by Tosoh Corporation was used as the column.

  Synthesis of other polyarylate resins and measurement of their weight average molecular weight can also be performed by the same method as described above.

Synthesis Example 2 Synthesis of chlorogallium phthalocyanine (1)
72.6 g of o-phthalonitrile, 25 g of gallium trichloride, and 375 ml of α-chloronaphthalene were reacted at 200 ° C. for 4 hours in a nitrogen atmosphere. After the reaction, the precipitated product was cooled to 130 ° C. and filtered. The obtained product was dispersed and washed with N, N-dimethylformamide at 130 ° C. for 1 hour and filtered. Next, after washing | cleaning with the filter with methanol, it dried under reduced pressure and obtained 39.8g of chlorogallium phthalocyanine.

Synthesis Example 3 Synthesis of chlorogallium phthalocyanine (2)
30 g of chlorogallium phthalocyanine obtained in Synthesis Example 2 was subjected to a dry milling treatment for 24 hours in a ball mill using 100 g of agate ball having a diameter of 10 mm and 200 g of agate ball having a diameter of 20 mm.

  Milling was performed for 20 hours at 22 ° C. in a sand mill using 7 g of chlorogallium phthalocyanine crystals after dry milling and 280 g of benzyl alcohol using 420 g of glass beads having a diameter of 1 mm. Chlorogallium phthalocyanine was filtered off from the obtained dispersion, washed with methanol, and dried under reduced pressure to obtain a Bragg angle 2θ ± 0.2 ° of 7.4 °, 16.6 in CuKα characteristic X-ray diffraction. 6.3 g of crystalline chlorogallium phthalocyanine (ClGaPc) having peaks at °, 25.5 ° and 28.2 ° were obtained.

(Synthesis Example 4) Synthesis of Hydroxygallium Phthalocyanine 35 g of chlorogallium phthalocyanine obtained in Synthesis Example 2 was gradually added to 1050 g of concentrated sulfuric acid cooled to 0 ° C. and dissolved, followed by stirring at 0 ° C. for 30 minutes. Further, the mixture was slowly dropped into 5250 g of ice water while stirring to cause reprecipitation.

  After reprecipitation, filtration was performed, and the obtained powder was dispersed and washed in 2500 g of ion-exchanged water and filtered again. Further, the obtained powder was dispersed and washed in 2500 g of 2% ammonia water, and further washed thoroughly with ion-exchanged water, and the resulting solid was dried under reduced pressure. In this way, 33.9 g of low crystalline hydroxygallium phthalocyanine was obtained.

  The obtained low crystalline hydroxygallium phthalocyanine (7 g) and N, N-dimethylformamide (210 g) were milled at 22 ° C. for 5 hours in a sand mill using 300 g of glass beads having a diameter of 1 mm. From this dispersion, hydroxygallium phthalocyanine was filtered off, washed with methanol, and dried under reduced pressure to obtain 7.4 ° and 28.2 ° with Bragg angles 2θ ± 0.2 ° in CuKα characteristic X-ray diffraction. 6.4 g of crystalline gallium phthalocyanine (HOGaPc) having a peak was obtained.

In addition, the measurement of the X-ray diffraction in this invention was performed on condition of the following using a CuK alpha ray.
Measuring instrument used: Fully automated X-ray diffractometer MXP18, manufactured by Mac Science
X-ray tube: Cu
Tube voltage: 50 kV
Tube current: 300mA
Scan method: 2θ / θ scan Scan speed: 4 deg. / Min
Sampling interval: 0.020 deg.
Start angle (θ): 3 deg.
Stop angle (θ): 40 deg.
Divergence slit: 0.5 deg.
Scattering slit: 0.5 deg.
Receiving slit: 0.3mm
Uses curved monochromator

  Hereinafter, all the polyarylate resins used in the examples have a molar ratio of terephthalic acid structure to isophthalic acid structure (terephthalic acid structure: isophthalic acid structure) of 50:50 (molar ratio).

(Example 1)
An aluminum cylinder having a diameter of 30 mm and a length of 260 mm was used as a support.

Next, 10 parts of SnO ₂ coated barium sulfate (conductive particles), 2 parts of titanium oxide (for resistance adjustment), 6 parts of phenol resin, 0.001 part of silicone oil, and 4 parts of methanol / 16 parts of methoxypropanol The mixed solvent was dispersed for 2 hours with a sand mill using glass beads having a diameter of 1 mm to prepare a coating solution for a conductive layer.

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

  Next, 5 parts of N-methoxymethylated nylon and 1 part of copolymer nylon were dissolved in a mixed solvent of 65 parts of methanol / 30 parts of n-butanol to prepare an intermediate layer coating solution.

  This intermediate layer coating solution was dip coated on the conductive layer and dried at 100 ° C. for 10 minutes to form an intermediate layer having a thickness of 0.5 μm.

  Next, 15 parts of hydroxygallium phthalocyanine (charge generation material) synthesized in Synthesis Example 4, 10 parts of polyvinyl butyral (trade name: ESREC BX-1, manufactured by Sekisui Chemical Co., Ltd.) and 300 parts of cyclohexanone were added to a diameter of 1 mm. Was dispersed for 1 hour at 20 ° C. in a sand mill using glass beads, and then 300 parts of ethyl acetate was added to prepare a charge generation layer coating solution.

  The 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 0.2 μm.

  Next, 9 parts of a compound (charge transport material) having a structure represented by the following formula:

  1 part of a compound (charge transport material) having a structure represented by the following formula,

  12 parts of a homopolymer polyarylate resin (binder resin, weight average molecular weight: 100000) having a repeating structural unit represented by the above formula (PA-9), and an oxidation having a structure represented by the above formula (3) 1.2 parts of the inhibitor was dissolved in a mixed solvent of 50 parts of dimethoxymethane / 50 parts of chlorobenzene to prepare a coating solution for charge transport layer.

  The charge transport layer coating solution was dip coated on the charge generation layer and dried at 120 ° C. for 60 minutes to form a charge transport layer having a thickness of 28 μm.

  In this manner, an electrophotographic photoreceptor having a charge transport layer as a surface layer was produced.

  The produced electrophotographic photosensitive member was mounted on a modified machine of a laser beam printer LaserJet 4000 manufactured by Hewlett-Packard Company for evaluation. Remodeling made the exposure device variable. The LaserJet 4000 includes a process cartridge having an electrophotographic photosensitive member and a process cartridge having a developing unit.

  The produced electrophotographic photosensitive member is charged so that the dark portion potential (Vd) becomes −600 V by the above evaluation apparatus, and the amount of light necessary for the bright portion potential (Vl) to be −150 V is measured. Sensitivity was used. The surface potential of the electrophotographic photosensitive member was measured by removing a process cartridge having a developing means from the evaluation apparatus and inserting a potential measuring apparatus there. The potential measuring device is configured by arranging a potential measuring probe at a developing position of a process cartridge having developing means, and the position of the potential measuring probe with respect to the electrophotographic photosensitive member is in the axial direction of the electrophotographic photosensitive member which is a drum shape. And the gap between the potential measurement probe and the surface of the electrophotographic photosensitive member was 3 mm.

A portion of the produced electrophotographic photosensitive member is shielded from light, and a non-light-shielded portion is irradiated with 1500 lx fluorescent lamp light for 15 minutes, then attached to the evaluation apparatus, and the light portion potential is measured one minute after the light irradiation, A potential difference ΔVl between the non-light-shielding part and the light-shielding part was defined as a photo memory (PM).
ΔVl (PM) = | non-light-shielding part Vl |-| light-shielding part Vl |
Further, in the first turn (95 mm length) of the electrophotographic photosensitive member, a solid white portion (no exposure, same as Vd) 30 mm, a solid black portion (exposure portion, Vl) 30 mm, a solid white portion 35 mm in this order, and 2 An image composed of a halftone portion was output after the lap.

  Next, the surface potential of the electrophotographic photosensitive member when this image is output is measured, and in the second half-tone image portion of the electrophotographic photosensitive member, the portion corresponding to the exposed portion of the first turn and the first turn are measured. The potential difference (ghost potential) in the portion corresponding to the non-exposed portion was measured.

  Further, an image having a printing ratio of 6% was subjected to a 10,000 sheet passing durability test in an intermittent mode in which each printing is stopped once in a 23 ° C./55% RH environment. The amount of wear on the surface of the electrophotographic photosensitive member after durability was measured.

  When the toner runs out during the endurance, the process cartridge having the developing means was replaced and evaluated.

  The evaluation results are shown in Table 1.

(Example 2)
In Example 1, an electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that the antioxidant used in the charge transport layer was changed to the antioxidant having the structure represented by the above formula (7). ,evaluated. The evaluation results are shown in Table 1.

(Example 3)
In Example 1, an electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the antioxidant used in the charge transport layer was changed to the antioxidant having the structure represented by the above formula (5). ,evaluated. The evaluation results are shown in Table 1.

Example 4
In Example 1, an electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the antioxidant used in the charge transport layer was changed to the antioxidant having the structure represented by the above formula (6). ,evaluated. The evaluation results are shown in Table 1.

(Example 5)
In Example 1, an electrophotographic photoreceptor was prepared and evaluated in the same manner as in Example 1 except that the amount of the antioxidant used in the charge transport layer was changed to 2.4 parts. The evaluation results are shown in Table 1.

(Example 6)
In Example 1, an electrophotographic photosensitive member was produced and evaluated in the same manner as in Example 1 except that the amount of the antioxidant used in the charge transport layer was changed to 4.2 parts. The evaluation results are shown in Table 1.

(Example 7)
In Example 1, an electrophotographic photosensitive member was produced and evaluated in the same manner as in Example 1 except that the amount of the antioxidant used in the charge transport layer was changed to 0.6 part. The evaluation results are shown in Table 1.

(Example 8)
In Example 1, the polyarylate resin used for the charge transport layer has a repeating structural unit represented by the above formula (PA-2) and a repeating structural unit represented by the above formula (PA-14) in a ratio of 1: 1. An electrophotographic photosensitive member was prepared and evaluated in the same manner as in Example 1 except that the binary copolymer polyarylate resin was used. The evaluation results are shown in Table 1.

Example 9
In Example 1, an electrophotographic photoreceptor was prepared and evaluated in the same manner as in Example 1 except that the thickness of the charge transport layer was changed to 30 μm. The evaluation results are shown in Table 1.

(Example 10)
In Example 1, an electrophotographic photoreceptor was prepared and evaluated in the same manner as in Example 1 except that the thickness of the charge transport layer was changed to 35 μm. The evaluation results are shown in Table 1.

(Example 11)
In Example 1, an electrophotographic photoreceptor was prepared and evaluated in the same manner as in Example 1 except that the charge generation material used in the charge generation layer was changed to chlorogallium phthalocyanine synthesized in Synthesis Example 3. The evaluation results are shown in Table 1.

(Comparative Example 1)
In Example 1, an electrophotographic photoreceptor was prepared and evaluated in the same manner as in Example 1 except that no antioxidant was used in the charge transport layer. The evaluation results are shown in Table 1.

(Comparative Example 2)
In Example 1, an electrophotographic photosensitive member was produced and evaluated in the same manner as in Example 1 except that the amount of the antioxidant used in the charge transport layer was changed to 0.36 parts. The evaluation results are shown in Table 1.

(Comparative Example 3)
In Example 1, an electrophotographic photoreceptor was prepared and evaluated in the same manner as in Example 1 except that the amount of the antioxidant used in the charge transport layer was changed to 4.8 parts. The evaluation results are shown in Table 1.

(Comparative Example 4)
In Example 8, an electrophotographic photoreceptor was prepared and evaluated in the same manner as in Example 8 except that no antioxidant was used in the charge transport layer. The evaluation results are shown in Table 1.

(Comparative Example 5)
In Example 1, the charge generation material used in the charge generation layer has a structure represented by the following formula, and has a Bragg angle 2θ ± 0.2 ° of 9.5 ° and 27.1 ° in CuKα characteristic X-ray diffraction. An electrophotographic photoreceptor was prepared and evaluated in the same manner as in Example 1 except that the crystal form was changed to oxytitanium phthalocyanine (TiOPc) having a peak. The evaluation results are shown in Table 1.

(Comparative Example 6)
In Comparative Example 5, an electrophotographic photoreceptor was prepared and evaluated in the same manner as in Comparative Example 5 except that no antioxidant was used in the charge transport layer. The evaluation results are shown in Table 1.

(Comparative Example 7)
In Example 1, an electrophotographic photoreceptor was prepared and evaluated in the same manner as in Example 1 except that the charge generation material used in the charge generation layer was changed to an azo pigment having a structure represented by the following formula. The evaluation results are shown in Table 1.

(Comparative Example 8)
In Comparative Example 7, an electrophotographic photoreceptor was prepared and evaluated in the same manner as in Comparative Example 7 except that no antioxidant was used in the charge transport layer. The evaluation results are shown in Table 1.

(Comparative Example 9)
In Example 9, an electrophotographic photoreceptor was prepared and evaluated in the same manner as in Example 9 except that no antioxidant was used in the charge transport layer. The evaluation results are shown in Table 1.

(Comparative Example 10)
In Example 10, an electrophotographic photoreceptor was prepared and evaluated in the same manner as in Example 10 except that the antioxidant was not used in the charge transport layer. The evaluation results are shown in Table 1.

(Comparative Example 11)
In Example 1, an electrophotographic photosensitive member was produced and evaluated in the same manner as in Example 1 except that the thickness of the charge transport layer was changed to 20 μm. The evaluation results are shown in Table 1.

(Comparative Example 12)
In Comparative Example 11, an electrophotographic photoreceptor was prepared and evaluated in the same manner as Comparative Example 11 except that no antioxidant was used in the charge transport layer. The evaluation results are shown in Table 1.

(Comparative Example 13)
In Example 1, an electrophotographic photosensitive member was produced and evaluated in the same manner as in Example 1 except that the thickness of the charge transport layer was changed to 25 μm. The evaluation results are shown in Table 1.

(Comparative Example 14)
In Comparative Example 13, an electrophotographic photosensitive member was produced and evaluated in the same manner as Comparative Example 13 except that no antioxidant was used in the charge transport layer. The evaluation results are shown in Table 1.

  As described above, according to the present invention, in the electrophotographic photoreceptor using the polyarylate resin as the binder resin in the charge transport layer which is the surface layer and having a thick charge transport layer, It is possible to provide an electrophotographic photosensitive member in which generated photo memory and ghost are suppressed, a process cartridge and an electrophotographic apparatus having the electrophotographic photosensitive member.

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. 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.

Explanation of symbols

1 Electrophotographic photosensitive member 2 Axis 3 Charging means (primary charging means)
4 exposure light (image exposure light)
Reference Signs List 5 Developing means 6 Transfer means 7 Cleaning means 8 Fixing means 9 Process cartridge 91 First process cartridge 92 Second process cartridge 10 Guide means P Transfer material

Claims (4)

An electrophotographic photoreceptor having a charge generation layer and a charge transport layer in this order on a support, wherein at least one binder resin in the charge transport layer is a polyarylate resin, and the film of the charge transport layer In an electrophotographic photoreceptor having a thickness of 28 μm or more,
The charge generation layer contains gallium phthalocyanine;
The electrophotographic photoreceptor, wherein the charge transport layer contains an antioxidant in an amount of 5% by weight to less than 40% by weight based on the total weight of the binder resin in the charge transport layer.   The antioxidant is at least one kind of antioxidant selected from the group consisting of an antioxidant having a hindered phenol structure, an antioxidant having a benzotriazole structure, and an antioxidant containing a phosphorus atom. The electrophotographic photosensitive member according to claim 1.   3. The electrophotographic photosensitive member according to claim 1 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 detachably attached to the electrophotographic apparatus main body. Process cartridge characterized by being.   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.

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