JP2013238667A - Electrophotographic photoreceptor, process cartridge, and electrophotographic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor having excellent potential stability even if the photoreceptor is repeatedly used, and a process cartridge and an electrophotographic device including the electrophotographic photoreceptor.SOLUTION: A charge transport layer as a surface layer of an electrophotographic photoreceptor contains polycarbonate resin having a specified repeating structural unit, wherein the amount of volatile components in the case of holding the polycarbonate resin for one hour at 150°C is 10 ppm or less.

Description

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

  As an electrophotographic photosensitive member, there is an organic electrophotographic photosensitive member (hereinafter referred to as “electrophotographic photosensitive member”) containing an organic photoconductive substance (charge generating substance). In the electrophotographic process, various materials (hereinafter also referred to as “contact members”) such as a developer, a charging member, a cleaning blade, paper, and a transfer member are 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. Particularly, in recent years, as the durability of an electrophotographic photosensitive member is improved, the electrophotographic photosensitive member is required to have a sustained effect of reducing image deterioration due to contact stress.

  Patent Documents 1 and 2 propose an electrophotographic photosensitive member containing a polycarbonate resin incorporating a siloxane structure having a specific structure. Solvent crack resistance due to a releasing action and lubrication of the surface of the electrophotographic photosensitive member in the initial stage of use are disclosed. The effect of improving the sex has been reported.

Japanese Patent Laid-Open No. 06-075415 JP 2007-199688 A

  Patent Document 1 discloses an electrophotographic photosensitive member having a surface layer in which a polycarbonate resin incorporating a siloxane structure having a specific structure in the main chain of a resin and a copolymer polycarbonate resin having a specific structure not having a siloxane structure are mixed. . The electrophotographic photoreceptor of Patent Document 1 has been shown to improve solvent crack resistance and toner adhesion resistance.

  However, in the electrophotographic photoreceptor of Patent Document 1, as a result of investigations by the present inventors, it has been found that there is room for improvement in potential stability during repeated use of the electrophotographic photoreceptor.

  Patent Document 2 discloses an electrophotographic photosensitive member having a surface layer in which a polycarbonate resin incorporating a siloxane structure having a specific structure at the main chain and terminal of the resin and a polycarbonate resin having no siloxane structure are mixed. ing. And it is shown that the lubricity at the initial stage of use is improved.

  However, as a result of studies by the present inventors, it has been found that there is room for improvement in potential stability during repeated use of the electrophotographic photosensitive member.

  When a resin incorporating a siloxane structure is used, potential stability during repeated use tends to be a problem.

  An object of the present invention is to provide an electrophotographic photoreceptor excellent in potential stability during repeated use, and a process cartridge and an electrophotographic apparatus having the electrophotographic photoreceptor.

The present invention relates to an electrophotographic photoreceptor having a support, a charge generation layer provided on the support, and a charge transport layer provided on the charge generation layer, wherein the charge transport layer is a surface layer. In
The charge transport layer contains a polycarbonate resin having a repeating structural unit represented by the following formula (A), a repeating structural unit represented by the following formula (B) and a repeating structural unit represented by the following formula (C), The content of the siloxane moiety in the polycarbonate resin is 5% by mass or more and 40% by mass or less, and the content of the repeating structural unit represented by the following formula (B) in the polycarbonate resin is 10% by mass or more and 30% by mass or less. Yes, the content of the repeating structural unit represented by the following formula (C) in the polycarbonate resin is 25% by mass or more and 85% by mass or less, and the amount of volatile components when the polycarbonate resin is held at 150 ° C. for 1 hour is An electrophotographic photosensitive member characterized by being 10 ppm or less.

  In the formula (A), n represents an average value of the number of repetitions of the structure in each parenthesis, and is 20 or more and 60 or less.

  In formula (B), Y represents an oxygen atom or a sulfur atom.

  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 electrophotographic apparatus main body. A process cartridge.

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

  According to the present invention, it is possible to provide an electrophotographic photoreceptor excellent in potential stability during repeated use, and a process cartridge and an electrophotographic apparatus having the electrophotographic photoreceptor.

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.

  As described above, the electrophotographic photosensitive member of the present invention has a support, a charge generation layer provided on the support, and a charge transport layer provided on the charge generation layer, and the charge transport layer. Is an electrophotographic photoreceptor having a surface layer. And this charge transport layer contains the polycarbonate resin which has a siloxane site | part whose amount of volatile components when it hold | maintains at 150 degreeC for 1 hour is 10 ppm or less.

  Furthermore, the polycarbonate resin having the siloxane moiety used in the present invention has a repeating structural unit represented by the following formula (A), a repeating structural unit represented by the following formula (B), and a repeating structure represented by the following formula (C). Has units. Further, the content of the siloxane moiety in the polycarbonate resin is 5% by mass or more and 40% by mass or less, and the content of the repeating structural unit represented by the following formula (B) in the polycarbonate resin is 10% by mass or more and 30% by mass. The content of the repeating structural unit represented by the following formula (C) in the polycarbonate resin is 25% by mass or more and 85% by mass or less.

  In the formula (A), n represents an average value of the number of repetitions of the structure in each parenthesis, and is 20 or more and 60 or less.

  In formula (B), Y represents an oxygen atom or a sulfur atom.

  In the formula (A), n represents an average value of the number of repetitions of the structure in each parenthesis, and is 20 or more and 60 or less. Furthermore, it is preferable that it is 30 or more and 50 or less from a viewpoint of coexistence of sustained stress relaxation and the potential fluctuation suppression at the time of repeated use. Further, the number of repetitions n of the structure in parentheses is preferably within a range of ± 10% of the value represented by the average value of the number of repetitions of n, from the viewpoint of stably obtaining the effects of the present invention.

  Table 1 shows examples of the repeating structural unit represented by the above formula (A).

  Among these, the repeating structural unit example (A-3) is preferable.

  Further, the polycarbonate resin used in the present invention may have a siloxane structure represented by the following formula (E) as a terminal structure.

  M in the formula (E) represents an average value of the number of repetitions of the structure in each parenthesis, and is 20 or more and 60 or less.

  Table 2 shows an example of a polycarbonate resin having a repeating structural unit represented by the formula (A) as a siloxane structure and a repeating structural unit represented by the formula (E) as a terminal structure.

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

  Among these, the repeating structural unit represented by the above formula (B-1) is preferable.

  Moreover, the polycarbonate resin used for this invention contains the repeating structural unit shown by Formula (B) with respect to the total mass of polycarbonate resin at 10 mass% or more and 30 mass% or less.

  Next, the repeating structural unit represented by the formula (C) will be described.

  The polycarbonate resin used in the present invention contains the repeating structural unit represented by the formula (C) in an amount of 25% by mass to 85% by mass with respect to the total mass of the polycarbonate resin. Moreover, the polycarbonate resin used for this invention contains a siloxane site | part with 5 mass% or more and 40 mass% or less with respect to the total mass of polycarbonate resin.

  In the present invention, the siloxane moiety is a moiety comprising silicon atoms at both ends constituting the siloxane moiety and groups bonded thereto, and oxygen atoms, silicon atoms and groups bonded to the silicon atoms sandwiched between the silicon atoms at both ends. is there.

  Specifically, in the present invention, the siloxane moiety is, for example, a moiety surrounded by a broken line below in the case of a repeating structural unit represented by the following formula (AS). Further, the polycarbonate resin A may have a siloxane structure as a terminal structure. In that case, similarly, a siloxane site is a site surrounded by the following broken line in the case of a repeating structural unit represented by the following formula (ES), for example. In this case, the content of the siloxane moiety in the polycarbonate resin A is such that the total of the following broken line portions of the following formula (AS) and the following formula (ES) is 5% by mass or more based on the total mass of the polycarbonate resin. It is below mass%.

  That is, the structure shown below is a siloxane site of the above formula (AS) and the above formula (ES).

  The content of the siloxane moiety relative to the total mass of the polycarbonate resin used in the present invention can be analyzed by a general analytical method. Examples of analysis methods are shown below.

  First, the charge transport layer which is the surface layer of the electrophotographic photosensitive member is dissolved with a solvent. Thereafter, various materials contained in the charge transport layer, which is the surface layer, are fractionated by a fractionation apparatus capable of separating and recovering each composition component such as size exclusion chromatography and high performance liquid chromatography. The separated polycarbonate resin is hydrolyzed in the presence of an alkali or the like to decompose into a carboxylic acid moiety, a bisphenol and a phenol moiety. The obtained bisphenol and the phenol moiety are subjected to nuclear magnetic resonance spectrum analysis and mass spectrometry, and the number of repetitions and molar ratio of the siloxane moiety are calculated and converted to the content (mass ratio).

  The polycarbonate resin used in the present invention is a copolymer of a repeating structural unit represented by the formula (A), a repeating structural unit represented by the formula (B), and a repeating structural unit represented by the formula (C). And the copolymerization form may be any form such as block copolymerization, random copolymerization, and alternating copolymerization.

  The weight average molecular weight of the polycarbonate resin used in the present invention is preferably 30,000 or more and 150,000 or less from the viewpoint of not forming an aggregate of the charge transport material. Furthermore, it is more preferable that it is 70,000 or more and 140,000 or less.

  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-2007-79555 in accordance with a conventional method.

In the present invention, the copolymerization ratio of the polycarbonate resin is confirmed by a conversion method based on the peak position and peak area ratio of hydrogen atoms (hydrogen atoms constituting the resin) by ¹ H-NMR measurement of the resin, which is a general technique. can do.

  The polycarbonate resin used in the present invention can be synthesized by a transesterification method or a phosgene method.

  In this invention, it is preferable that the amount of volatile components when this polycarbonate resin is hold | maintained at 150 degreeC for 1 hour is 10 ppm or less. The analysis of the amount of volatile components of the resin in the present invention can be performed by using a general gas chromatography, and a headspace sampler capable of holding a sample at 150 ° C. for 1 hour before measuring the gas chromatography. It is desirable to use the equipment provided.

  The charge transport layer may contain the polycarbonate resin and a polycarbonate resin D having a repeating structural unit represented by the following formula (D).

  In addition to containing the repeating structural unit represented by the above formula (D), other repeating structural units may be contained as a copolymer structure with the above formula (D). The content of the repeating structural unit represented by the above formula (D) is 50% by mass with respect to the total mass of the resin in the charge transport layer from the viewpoint of forming a uniform film without forming an aggregate of the charge transport material. It is preferable to contain above. Furthermore, it is preferable that the repeating structural unit represented by the above formula (D) is contained in an amount of 70% by mass or more.

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

  Among these, the repeating structural unit represented by the above formula (2-1) or (2-3) is preferable.

  Examples of the charge transport material include triarylamine compounds, hydrazone compounds, styryl compounds, and styrylbenzene compounds.

  Specific examples of the charge transport material used in the present invention are shown below.

  Among these, the charge transport materials include the above formulas (1-1), (1-3), (1-5), (1-7), (1-11), (1-13), (1- 14) A charge transport material having a structure represented by (1-15) or (1-17) is preferred.

  The charge transport layer, which is the surface layer of the electrophotographic photosensitive member of the present invention, contains a polycarbonate resin containing a siloxane moiety as a resin, but may further be used by mixing other resins. Examples of other resins that may be used in combination include acrylic resins, polyester resins, and polycarbonate resins. Among these, a polyester resin is preferable in terms of improving electrophotographic characteristics.

  Next, a synthesis example of a polycarbonate resin having a siloxane moiety used in the present invention is shown. The polycarbonate resin can be synthesized using the synthesis method described in JP-A-2007-199688.

  In the present invention, the same synthesis method is used, using the raw material corresponding to the repeating structural unit represented by formula (A), the repeating structural unit represented by formula (B), and the repeating structural unit represented by formula (C). The polycarbonate resins used in the present invention shown in Table 3 were synthesized. A synthesis example is shown below.

(Synthesis Example 1)
To 250 ml of a 10% aqueous sodium hydroxide solution, 53.6 g of bisphenol represented by the following formula (BM) and 10.1 g of phenol represented by the following formula (CM) were added and dissolved. To this solution, 150 ml of dichloromethane was added and stirred, and 50 g of phosgene was blown in over 1 hour while maintaining the solution at 10 ° C. or higher and 15 ° C. or lower. When about 70% of phosgene was blown, a siloxane compound (n = 40) represented by the following formula (AM) was added to the 6.25 g solution. After the introduction of phosgene was completed, the reaction was emulsified by vigorous stirring, 0.2 ml of triethylamine was added, and the mixture was stirred for 1 hour. Thereafter, the dichloromethane phase was neutralized with phosphoric acid and further washed with water until the pH reached about 7. Subsequently, this liquid phase was dropped into isopropanol, and precipitated and filtered to obtain a solid. Thereafter, the solid obtained as a purification was dissolved again in 300 ml of dichloromethane, and washed with water three times. This liquid phase was dropped into isopropanol and precipitated and filtered. The obtained solid was dried under reduced pressure at 120 ° C. for 24 hours to obtain a white powdery polymer (polycarbonate resin according to the present invention, PC-Si (1)). The obtained polymer was analyzed by infrared absorption spectrum, absorption by carbonyl group 1750 cm ^-1, absorption by absorbent and carbonate bonds with ether bond at 1240 cm ^-1. Moreover, the peak attributable to 1100 cm ^-1 or 1000 cm ^-1 The following siloxane was also confirmed. Moreover, as a result of measuring the obtained polymer by gel permeation chromatography, it turned out that it is the weight average molecular weight (Mw) 110000 in polystyrene conversion. In addition, using gas chromatography to which a headspace sampler was connected and holding the obtained PC-Si (1) at 150 ° C. for 1 hour, gas chromatography measurement showed that the amount of volatile components was 2.5 ppm. there were.

  Table 3 shows the weight average molecular weight of the polycarbonate resin synthesized in the same manner as in Synthesis Example 1, the content of the siloxane moiety in the polycarbonate resin, and the amount of volatile components when held at 150 ° C. for 1 hour.

  In Table 3, polycarbonate resins PC-Si (1) to (17) are polycarbonate resins having only a repeating structural unit represented by the formula (A) as a siloxane moiety. The polycarbonate resins PC-Si (18) to (27) are polycarbonate resins having both a repeating structural unit represented by the formula (A) and a repeating structural unit represented by the formula (E) as siloxane sites. The content of the siloxane moiety in Table 3 is the total amount of the siloxane moiety contained in the repeating structural unit represented by the formula (A) with respect to the polycarbonate resin and the repeating structural unit represented by the formula (E) as described above. In the synthesis of the polycarbonate resins PC-Si (18) to (27), the raw materials in the formulas (AM) and (EM) were synthesized so that the raw material ratio was 1: 1.

  In the polycarbonate resin PC-Si (2), the maximum value of the number n of repetitions in parentheses of the structure represented by the above formula (A-3) was 43, and the minimum value was 37. Further, in the polycarbonate resin PC-Si (21), the maximum value of the number of repetitions n in the parenthesis of the structure represented by the above formula (A) is 43, and the minimum value is 37. The structure represented by the above formula (E) The maximum number of repetitions m in parentheses was 42, and the minimum value was 38.

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

  The electrophotographic photosensitive member of the present invention is an electrophotographic photosensitive member having a support, a charge generation layer provided on the support, and a charge transport layer provided on the charge generation layer. The charge transport layer is an electrophotographic photosensitive member whose surface layer (uppermost layer) is an electrophotographic photosensitive member.

  The charge transport layer of the electrophotographic photosensitive member of the present invention contains the above polycarbonate resin and a charge transport material. In general, a cylindrical electrophotographic photosensitive member in which a photosensitive layer is formed on a cylindrical support is widely used as the electrophotographic photosensitive member. However, a belt shape, a sheet shape, or the like may be used. It is.

[Support]
The support used in the electrophotographic photosensitive member of the present invention is preferably a conductive one (conductive support), and examples of the material include aluminum, aluminum alloy, and stainless steel. In the case of a support made of aluminum or 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. 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, silver, and metal oxide particles such as conductive tin oxide and ITO.

  Examples of the resin used for the conductive layer include polyester, polycarbonate, polyvinyl butyral, acrylic resin, silicone resin, epoxy resin, melamine resin, urethane resin, phenol resin, and alkyd resin.

  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 photoreceptor of the present invention, an undercoat layer (also referred to as an intermediate layer) may be provided between the support or the conductive layer and the charge generation layer.

  The undercoat layer can be formed by applying a coating solution for an undercoat layer containing a resin on a support or a conductive layer and drying or curing it.

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

  The thickness of the undercoat 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. The undercoat layer may contain semiconductive particles, an electron transport 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 undercoat 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, polyester, butyral resin, polyvinyl acetal, 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 generation material to the resin is preferably 0.1 parts by mass or more and 10 parts by mass or less, and preferably 1 part by mass or more and 3 parts by mass or less with respect to 1 part by mass of the resin. More preferred.

  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 which is the surface layer of the electrophotographic photosensitive member of the present invention contains the polycarbonate resin and the charge transport material, but may be further mixed with other resins as described above. Other resins that may be used in combination are as described above. The charge transport materials used in the charge transport layer of the present invention can be used alone or in combination of two or more.

  The charge transport layer can be formed by applying a charge transport layer coating solution obtained by dissolving a charge transport material and each of the above resins in a solvent, and drying it.

  The ratio of the charge transport material to the resin is preferably 0.4 parts by mass or more and 2 parts by mass or less, and 0.5 parts by mass or more and 1.2 parts by mass or less with respect to 1 part by mass of the resin. It is more preferable that

  Examples of the solvent used in the charge transport layer coating solution include ketone solvents, ester solvents, ether solvents, and aromatic hydrocarbon solvents. These solvents may be used alone or in combination of two or more. Among these solvents, use of an ether solvent or an aromatic hydrocarbon solvent is preferable from the viewpoint of resin solubility.

  The film thickness of the charge transport layer is preferably 5 μm or more and 50 μm or less, and more preferably 10 μm or more and 35 μm or less.

  In addition, an antioxidant, an ultraviolet absorber, a plasticizer, and the like can be added to the charge transport layer as necessary.

  Various additives can be added to each layer of the electrophotographic photoreceptor of the present invention. Examples of the additive include deterioration inhibitors such as antioxidants, ultraviolet absorbers, and light resistance stabilizers, and particles such as organic particles and inorganic particles. Examples of the deterioration inhibitor include hindered phenol antioxidants, hindered amine light stabilizers, sulfur atom-containing antioxidants, and phosphorus atom-containing antioxidants. Examples of the organic particles include polymer resin particles such as fluorine atom-containing resin particles, polystyrene particles, and polyethylene resin particles. Examples of the inorganic particles include metal oxides such as silica and alumina.

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

[Electrophotographic equipment]
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 cylindrical electrophotographic photosensitive member, which is driven to rotate 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 unit 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. 1, 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. 1, an electrophotographic photosensitive member 1, a charging unit 3, a developing unit 5, and a cleaning unit 7 are integrally supported to form a cartridge, and electrophotography is performed using a guide unit 10 such as a rail of an electrophotographic apparatus main body. The process cartridge 9 is detachable from the apparatus main body.

  Hereinafter, the present invention will be described in more 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]
An aluminum cylinder having a diameter of 30 mm and a length of 260.5 mm was used as a support (conductive support).

Next, 10 parts of SnO ₂ coated barium sulfate (conductive particles), 2 parts of titanium oxide (resistance control pigment), 6 parts of phenol resin, 0.001 part of silicone oil (leveling agent), 4 parts of methanol and methoxy A conductive layer coating solution was prepared using a mixed solvent of 16 parts of propanol. The conductive layer coating solution was dip-coated on the aluminum cylinder and cured (heat cured) at 140 ° C. for 30 minutes to form a conductive layer having a thickness of 15 μm.

  Next, 3 parts of N-methoxymethylated nylon and 3 parts of copolymer nylon were dissolved in a mixed solvent of 65 parts of methanol and 30 parts of n-butanol to prepare an undercoat layer coating solution. This undercoat layer coating solution was dip-coated on the conductive layer and dried at 100 ° C. for 10 minutes to form an undercoat layer having a thickness of 0.7 μm.

  Next, Bragg angles (2θ ± 0.2 °) in CuKα characteristic X-ray diffraction of 7.5 °, 9.9 °, 16.3 °, 18.6 °, 25.1 °, and 28.3 ° 10 parts of a crystalline form of hydroxygallium phthalocyanine (charge generation material) having a strong peak was prepared. It was mixed with 250 parts of cyclohexanone and 5 parts of polyvinyl butyral (trade name: S-LEC BX-1, manufactured by Sekisui Chemical Co., Ltd.), and 1 in a 23 ± 3 ° C. atmosphere in a sand mill apparatus using glass beads having a diameter of 1 mm. Time dispersed. After dispersion, 250 parts of ethyl acetate was added to prepare a charge generation layer coating solution. This charge generation layer coating solution was dip-coated on the undercoat layer and dried at 100 ° C. for 10 minutes to form a charge generation layer having a thickness of 0.26 μm.

  Next, 4.8 parts of a charge transport material having a structure represented by the above formula (1-11) as a charge transport material, 1.2 parts of a charge transport material having a structure represented by the above formula (1-14), polycarbonate 2 parts of polycarbonate resin PC-Si (1) synthesized in Synthesis Example 1 as a resin and 8 parts of polycarbonate resin D (weight average molecular weight 80,000) having only a repeating structural unit represented by formula (D) A charge transport layer coating solution was prepared by dissolving in a mixed solvent of 60 parts of xylene and 20 parts of dimethoxymethane. This charge transport layer coating solution was dip-coated on the charge generation layer and dried at 120 ° C. for 1 hour to form a charge transport layer having a thickness of 16 μm.

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

  Next, evaluation will be described.

  The evaluation was performed with respect to fluctuations in the bright part potential (potential fluctuations) when 10,000 sheets were repeatedly used. As an evaluation apparatus, HP laser beam printer CP-4525 was remodeled so that the charging potential (dark part potential) of the electrophotographic photosensitive member could be adjusted. Evaluation was performed in an environment of a temperature of 23 ° C. and a relative humidity of 50%.

<Evaluation of potential fluctuation>
The exposure amount (image exposure amount) of the 780 nm laser light source of the evaluation apparatus was set so that the light amount on the surface of the electrophotographic photosensitive member was 0.37 μJ / cm ² . To measure the surface potential (dark part potential and bright part potential) of the electrophotographic photosensitive member, replace the jig and the developing device fixed so that the potential measuring probe is positioned 130 mm from the end of the electrophotographic photosensitive member. Then, it was carried out at the developing unit position. The dark part potential of the non-exposed part of the electrophotographic photosensitive member was set to −500 V, and the bright part potential that was light-attenuated from the dark part potential by laser irradiation was measured. In addition, 10,000 sheets of image output were continuously performed using A4 size plain paper, and the amount of change in the bright part potential before and after the evaluation was evaluated. A test chart having a printing ratio of 4% was used. The results are shown as potential fluctuations in Table 4.

[Examples 2 to 27]
In Example 1, an electrophotographic photosensitive member was produced and evaluated in the same manner as in Example 1 except that the polycarbonate resin was changed to PC-Si (2) to (27) as shown in Table 5. The results are shown as potential fluctuations in Table 4.

  The “siloxane content (% by mass)” in Table 4 means the content (% by mass) of the siloxane moiety relative to the total mass of the charge transport layer. “Volatile component amount / molecular weight in Table 3” means the volatile component amount and weight average molecular weight of the polycarbonate resin PC-Si shown in Table 3 when held at 150 ° C. for 1 hour.

[Comparative synthesis example]
In the same manner as in Synthesis Example 1, polycarbonate resins PC-Si (28) to (32) shown in Table 5 were synthesized. However, after completion of the reaction, neutralization was performed, and the polymer obtained by dropping into isopropanol and performing precipitation filtration was synthesized in the same manner as in Synthesis Example 1 except that the polymer was not washed with water and then dried at 120 ° C. for 2 hours. . Table 5 shows the weight average molecular weight of the polycarbonate resin synthesized in the same manner as in Synthesis Example 1, the content of the siloxane moiety in the polycarbonate resin, and the amount of volatile components when held at 150 ° C. for 1 hour.

[Comparative Examples 1-5]
In Example 1, an electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the polycarbonate resin PS-Si (1) was changed to PC-Si (28) to (32) shown in Table 5 above. ,evaluated. The results are shown in Table 6.

  The “siloxane content (% by mass)” in Tables 4 and 6 means the content (% by mass) of the siloxane moiety relative to the total mass of the charge transport layer. “Volatile component amount / molecular weight in Table 3” means the volatile component amount and weight average molecular weight of the polycarbonate resin PC-Si shown in Table 3 when held at 150 ° C. for 1 hour.

  The “siloxane content (% by mass)” in Table 6 means the content (% by mass) of the siloxane moiety relative to the total mass of the charge transport layer. “The amount of volatile components / molecular weight in Table 5” means the amount of volatile components and the weight average molecular weight of the polycarbonate resin PC-Si shown in Table 5 when held at 150 ° C. for 1 hour.

  Comparison between the example and Comparative Examples 1 to 5 shows that when the amount of volatile components is 10 ppm or less, the potential fluctuation is much better than that of the comparative example. Moreover, as a result of examination, it was suggested that the electric potential fluctuation | variation was changing according to the weight average molecular weight (Mw) of polycarbonate resin PC-Si. That is, it is shown that when the weight average molecular weight is large, the potential fluctuation tends to be improved.

DESCRIPTION OF SYMBOLS 1 Electrophotographic photoreceptor 2 Axis 3 Charging means 4 Exposure light 5 Developing means 6 Transfer means 7 Cleaning means 8 Fixing means 9 Process cartridge 10 Guide means P Transfer material

Claims (3)

In an electrophotographic photosensitive member having a support, a charge generation layer provided on the support, and a charge transport layer provided on the charge generation layer, wherein the charge transport layer is a surface layer.
The charge transport layer contains a polycarbonate resin having a repeating structural unit represented by the following formula (A), a repeating structural unit represented by the following formula (B) and a repeating structural unit represented by the following formula (C), The content of the siloxane moiety in the polycarbonate resin is 5% by mass or more and 40% by mass or less, and the content of the repeating structural unit represented by the following formula (B) in the polycarbonate resin is 10% by mass or more and 30% by mass or less. Yes, the content of the repeating structural unit represented by the following formula (C) in the polycarbonate resin is 25% by mass or more and 85% by mass or less, and the amount of volatile components when the polycarbonate resin is held at 150 ° C. for 1 hour is An electrophotographic photosensitive member characterized by being 10 ppm or less.

(In formula (A), n represents the average value of the number of repetitions of the structure in each parenthesis and is 20 or more and 60 or less.)

(In formula (B), Y represents an oxygen atom or a sulfur atom.)
  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 detachable from the main body of the electrophotographic apparatus. A process cartridge characterized by that.   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.