DESCRIPTION

ELECTROPHOTOGRAPHIC PHOTOSENSITIVE MEMBER, PROCESS CARTRIDGE , ELECTROPHOTOGRAPHIC

APPARATUS, AND METHOD OF MANUFACTURING

ELECTROPHOTOGRAPHIC PHOTOSENSITIVE MEMBER

Technical Field

[0001] The present invention relates to an electrophotographic photosensitive member, a process cartridge, an

electrophotographic apparatus, and a method of

manufacturing an electrophotographic photosensitive member.

Background Art

[0002] The electrophotographic photosensitive member mounted on electrophotographic apparatuses includes organic

electrophotographic photosensitive members (hereinafter, referred to as an "electrophotographic photosensitive member") containing an organic charge-generating

substance (organic photoconductive substance) . In the electrophotographic process, the surface of the

electrophotographic photosensitive member contacts a variety of objects such as a developer, a charging member, a cleaning blade, paper, and a transfer member (hereinafter, referred to as a "contacting member and the like"). For this reason, there has been a demand for reduction in deterioration of image quality caused by contact stress when the electrophotographic

photosensitive member contacts the contacting member and the like. Particularly, recently, persistency of a reducing effect on deterioration in image quality caused by the contact stress has been demanded of the

electrophotographic photosensitive member as the

durability of the electrophotographic photosensitive member is improved.

[0003] For continuous relaxation of the contact stress, PTL 1 proposes a method in which using a siloxane resin having a siloxane structure incorporated in the molecular chain, a matrix-domain structure is formed in a surface layer. The disclosure shows that using a polyester resin having a specific siloxane structure incorporated, continuous relaxation of the contact stress can be compatible with potential stability (suppression of fluctuation) when the photoreceptor is repeatedly used.

[0004] On the other hand, there has been a proposal that a

siloxane modified resin having a siloxane structure in the molecular chain is added to the surface layer of the electrophotographic photosensitive member. PTL 2

proposes an electrophotographic photosensitive member containing a polycarbonate-siloxane copolymerized resin having a specific siloxane structure incorporated, and reports that wear resistance and contamination

resistance are improved by introduction of the siloxane structure .

Citation List

Patent Literature

[0005]PTL 1: WO 2010/008095

PTL 2: Japanese Patent Application Laid-Open No. 2006- 328416

PTL 3: Japanese Patent Application Laid-Open No. 2007- 79555

Summary of Invention

Technical Problem

[0006] In the electrophotographic photosensitive member

disclosed in PTL 1, reduction in the continuous contact stress is compatible with the potential stability in repeating use. As a further examination by the present inventors, however, it was found out that the potential stability in repeating use can be further improved in the case where a charge-transporting substance having a specific structure is used as the charge-transporting substance .

[0007] In the electrophotographic photosensitive member disclosed in PTL 2 and containing the resin having an incorporated siloxane structure, the contamination resistance and wear resistance when the photoreceptor is used are improved. The resin having an incorporated siloxane structure and used in PTL 2 has a surface layer formed only with a resin containing a siloxane structure having a crosslinking moiety as a resin component.

Accordingly, it was found out that in the resin having an incorporated siloxane structure used in PTL 2, the continuous relaxation of the contact stress is not compatible with the potential stability in repeating use. Solution to Problem

[0008]An object of the present invention is to provide an

electrophotographic photosensitive member including a specific charge-transporting substance wherein

continuous relaxation of contact stress between the electrophotographic photosensitive member and a

contacting member and the like is highly compatible with potential stability in repeating use. Another object of the present invention is to provide a process cartridge having the electrophotographic photosensitive member, and an electrophotographic apparatus. Yet another object of the present invention is to provide a method of manufacturing the electrophotographic photosensitive member .

[0009] he objects above are achieved by the present invention below .

[0010] The present invention relates to an electrophotographic photosensitive member, comprising: a conductive support, a charge-generating layer which is provided on the conductive support and comprises a charge-generating substance, and a charge-transporting layer which is provided on the charge-generating layer and is a surface layer of the electrophotographic photosensitive member, wherein the charge-transporting layer has a matrix- domain structure having; a domain which comprises a polycarbonate resin A having a repeating structural unit represented by the following formula (A) and a repeating structural unit represented by the following formula (B) ; and a matrix which comprises, at least one resin selected from the group consisting of a polycarbonate resin C having a repeating structural unit represented by the following formula (C) and a polyester resin D having a repeating structural unit represented by the following formula (D),and at least one charge- transporting substance selected from the group

consisting of a compound represented by the following formula (1) and a compound represented by the following formula (1'), wherein the content of a siloxane moiety in the polycarbonate resin A is not less than 5% by mass and not more than 40% by mass relative to the total mass of the polycarbonate resin A.

wherein, in the formula (A) , "a" represents the number of repetitions of a structure within brackets, and an average of "a" in the polycarbonate resin A ranges from

wherein, in the formula (B) , R ²¹ to R ²⁴ each

independently represent a hydrogen atom or a methyl group; Y ¹ represents a single bond, a methylene group, an ethylidene group, a propylidene group, a phenylethylidene group, a cyclohexylidene group, or an oxygen atom;

[0012]

wherein, in the formula (C) , R ³¹ to R ³⁴ each

independently represent a hydrogen atom or a methyl group; Y ² represents a single bond, a methylene group, an ethylidene group, a propylidene group, a

phenylethylidene group, a cyclohexylidene group, or an oxygen atom;

wherein, in the formula (D) , R ⁴¹ to R ⁴⁴ each

independently represent a hydrogen atom or a methyl group; X represents a meta-phenylene group, a para- phenylene group, or a bivalent group having two para- phenylene groups bonded via an oxygen atom; Y ³

represents a single bond, a methylene group, an

ethylidene group, a propylidene group, a cyclohexylidene group, or an oxygen atom;

[0013]

wherein, in the formulae (1) and (1'), Ar represents a phenyl group or a phenyl group substituted with a methyl group or an ethyl group; Ar ² represents a phenyl group, a phenyl group substituted with a methyl group, a phenyl group substituted with a univalent group represented by -CH=CH-Ta, or a biphenyl group substituted with a univalent group represented by -CH=CH-Ta (wherein Ta represents a univalent group derived from a benzene ring of a triphenylamine by loss of one hydrogen atom, or a univalent group derived from a benzene ring of a

triphenylamine substituted with a methyl group or an ethyl group by loss of one hydrogen atom) ; R ¹ represents a phenyl group, a phenyl group substituted with a methyl group, or a phenyl group having a univalent group substituted with -CH=C (Ar ³ ) Ar ⁴ (wherein Ar ³ and Ar ⁴ each independently represent a phenyl group or a phenyl group substituted with a methyl group) ; R ² represents a hydrogen atom, a phenyl group, or a phenyl group

substituted with a methyl group.

[0014] he present invention also relates to a process

cartridge detachably attachable to a main body of an electrophotographic apparatus wherein the process cartridge integrally supports the electrophotographic photosensitive member and at least one device selected from the group consisting of a charging device, a developing device, a transferring device, and a cleaning device .

[0015] The present invention also relates to an

electrophotographic apparatus including the

electrophotographic photosensitive member, a charging device, an exposing device, a developing device, and a transferring device.

[0016] The present invention also relates to a method of

manufacturing the electrophotographic photosensitive member wherein the method includes a step of applying a coating solution for a charge-transporting layer

containing the polycarbonate resin A, at least one resin selected from the group consisting of the

polycarbonate resin C and the polyester resin D, and at least one charge-transporting substance selected from the group consisting of a compound represented by the formula (1) and a compound represented by the formula (1') onto the charge-generating layer, and drying the coating solution to form a charge-transporting layer. Advantageous Effects of Invention

[0017] The present invention can provide an electrophotographic photosensitive member including a specific charge- transporting substance wherein continuous relaxation of contact stress between the electrophotographic

photosensitive member and a contacting member and the like is highly compatible with potential stability in repeating use. The present invention can also provide a process cartridge having the electrophotographic

photosensitive member, and an electrophotographic apparatus. The present invention can also provide a method of manufacturing the electrophotographic

photosensitive member.

[0018] Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings. Brief Description of Drawings

[0019] [Fig. l]Fig. 1 is a drawing illustrating an example of a schematic configuration of an electrophotographic apparatus including a process cartridge having an electrophotographic photosensitive member according to the present invention.

Description of Embodiments

[0020] Hereinafter, a polycarbonate resin A having the

repeating structural unit represented by the formula (A) and the repeating structural unit represented by the formula (B) is referred to as a component a. At least one resin selected from a polycarbonate resin C having the repeating structural unit represented by the formula (C) and a polyester resin D having the repeating

structural unit represented by the formula (D) is referred to as a component β. At least one charge- transporting substance of compounds represented by the formulas (1) and (1') is referred to as a component γ.

[0021] The electrophotographic photosensitive member according to the present invention includes a conductive support, a charge-generating layer provided on the conductive support, and a charge-transporting layer which is provided on the charge-generating layer, and is a surface layer of the electrophotographic photosensitive member, wherein the charge-transporting layer has a matrix-domain structure having a matrix including the components β and γ and a domain including the component a, as described above.

[0022] In the matrix-domain structure in the present invention, the matrix corresponds to a sea, and the domain

corresponds to an island in a "sea island structure." The domain including the component a represents a granular (island-like) structure formed in the matrix including the components β and γ. In the domain

including the component a, the domains independently exist in the matrix. Such a matrix-domain structure can be recognized by observation of the surface of the charge-transporting layer or the cross section of the charge-transporting layer.

[0023] Observation of the state of the matrix-domain structure or measurement of the domain can be performed using a commercially available laser microscope, optical

microscope, electron microscope, or atomic force

microscope, for example. Using the microscope,

observation of the state of the matrix-domain structure or measurement of the domain can be performed at a predetermined magnification.

[0024] The number average particle size of the domain including the component a in the present invention is preferably not less than 100 nm and not more than 1,000 nm.

Narrower particle size distribution of the particle size of each domain is preferable from the viewpoint of persistency of a relaxing effect on the contact stress. The number average particle size in the present

invention is obtained as follows: 100 domains are

arbitrarily selected from the domains observed by the microscope in a vertical cross section of the charge- transporting layer of the present invention. The

largest diameters of the cut domains are measured, and averaged to calculate the number average particle size of the domain. By observation of the cross section of the charge-transporting layer with the microscope, the image information in the depth direction can be obtained, and a three-dimensional image of the charge-transporting layer can be obtained.

[0025] In order to form the matrix-domain structure in the

present invention, the content of the siloxane moiety in the polycarbonate resin A as the component a is

preferably not less than 1% by mass and not more than 20% by mass relative to the total mass of whole resins in the charge-transporting layer. From the viewpoint of compatibility of the continuous relaxation of the

contact stress with the potential stability in repeating use, the content of the siloxane moiety in the

polycarbonate resin A as the component a is also

preferably not less than 1% by mass and not more than 20% by mass relative to the total mass of the whole resins in the charge-transporting layer. More

preferably, at a content of not less than 2% by mass and not more than 10% by mass, the continuous relaxation of the contact stress and the potential stability in

repeating use can be further enhanced.

[0026] The matrix-domain structure of the charge-transporting layer of the electrophotographic photosensitive member according to the present invention can be formed using a coating solution for a charge-transporting layer

containing the components α, β and γ . Then, the coating solution for a charge-transporting layer is applied onto the charge-generating layer, and dried. Thereby, the electrophotographic photosensitive member according to the present invention can be manufactured.

[0027] The matrix-domain structure in the present invention is a structure in which the domain including the component a is formed in the matrix including the components β and γ. It is thought that the domain including the

component a is formed not only on the surface of the charge-transporting layer but also inside of the charge- transporting layer, and thereby the contact stress relaxation effect is persistently demonstrated.

Specifically, it is thought that the siloxane resin component having the contact stress relaxation effect reduced by friction with the member such as paper and the cleaning blade can be supplied from the domains in the charge-transporting layer.

[0028] The present inventors found out that in the case where a specific charge-transporting substance is used as the charge-transporting substance, the potential stability in repeating use can be further improved. Moreover, the present inventors presume the reason that the potential stability in repeating use is further enhanced in the electrophotographic photosensitive member according to the present invention containing a specific charge- transporting substance (component γ) as follows.

[0029] In the electrophotographic photosensitive member

according to the present invention having the charge- transporting layer having the matrix-domain structure, in order to suppress the potential fluctuation in repeating use, it is important to reduce the content of the charge-transporting substance in the domain in the formed matrix-domain structure as much as possible. In the case where the charge-transporting substance has high compatibility with the resin that forms the domain and has a siloxane structure incorporated, a larger amount of the charge-transporting substance is contained in the domain, charges are captured by the charge- transporting substance in the domain during repeating use of the photoreceptor, leading to insufficient potential stability.

[0030] In the electrophotographic photosensitive member

including a specific charge-transporting substance, improvement of properties is necessary by a resin having a siloxane structure incorporated for compatibility of the potential stability in repeating use with the persistent relaxing effect on the contact stress. The component γ in the present invention is a charge- transporting substance having high compatibility with the resin in the charge-transporting layer, and it is thought that the siloxane-containing resin undesirably contains a large amount of component γ in the domain, and the component γ is easily aggregated.

[0031] In the present invention, the domain including the

component a of the present invention is formed in the electrophotographic photosensitive member including the component γ. Thereby, a high charge-transporting ability can be kept. It is thought that the reason is that formation of the domain including the component a reduces the content of the component γ( specific charge- transporting substance) in the domain. It is thought that the reason is that the siloxane structure in the polycarbonate resin A as the component acan reduce the component γ having a structure easily compatible with the resin that remains in the domain.

[0032]<About component γ>

The component γ in the present invention is at least one charge-transporting substance selected from the

compounds represented by the following formulas (1) and d' ) :

wherein Ar ¹ represents a phenyl group, or a phenyl group substituted with a methyl group or an ethyl group; Ar ² represents a phenyl group, a phenyl group substituted with a methyl group, a phenyl group substituted with a univalent group represented by -CH=CH-Ta, or a biphenyl group substituted with a univalent group represented by -CH=CH-Ta (wherein Ta represents a univalent group derived from a benzene ring of a triphenylamine by loss of one hydrogen atom, or a univalent group derived from a benzene ring of a triphenylamine substituted with a methyl group or an ethyl group by loss of one hydrogen atom) ; R ¹ represents a phenyl group, a phenyl group substituted with a methyl group, or a phenyl group having a univalent group substituted with -CH=C (Ar ³ ) Ar (wherein Ar ³ and Ar ⁴ each independently represent a phenyl group or a phenyl group substituted with a methyl group) ; R ² represents a hydrogen atom, a phenyl group, or a phenyl group substituted with a methyl group.

] Hereinafter, specific examples of the component [γ] , i.e., the charge-transporting substances represented by the above formulas (1) and (1') will be shown:

[0034]Among these, the component γ is preferably a charge- transporting substance having a structure represented by the above formulas (1-1), (1-3), (1-5), and (1-7).

[0035]<About component a>

The component a in the present invention is a

polycarbonate resin A having the repeating structural unit represented by the following formula (A) and the repeating structural unit represented by the following formula (B) . The content of siloxane moiety in the polycarbonate resin A is not less than 5% by mass and not more than 40% by mass:

wherein "a" represents the number of repetitions of a structure within brackets, and an average of "a" in the polycarbonate resin A ranges from 20 to 200;

wherein R ²¹ to R ²⁴ each independently represent a

hydrogen atom or a methyl group; Y ¹ represents a single bond, a methylene group, an ethylidene group, a

propylidene group, a phenylethylidene group, a

cyclohexylidene group, or an oxygen atom.

[0036] Hereinafter, the component a, i.e., the polycarbonate resin A having the above repeating structural unit represented by the formula (A) and the above repeating structural unit represented by the formula (B) will be described .

[0037] "a" in the above formula (A) represents the number of repetitions of the structure within the brackets, and an average of "a" in the polycarbonate resin A ranges from 20 to 200. More preferably, "a" is not less than 30 and not more than 100 from the viewpoint of compatibility of the continuous contact stress relaxation with the potential stability in repeating use. Preferably, the number of repetitions "a" of the structure within the brackets in each repeating structural unit is within the range of ± 10% of the value shown as the average of the number of repetitions "a" because the effect of the present invention is stably obtained.

[0038] In Table 1, examples of the above repeating structural unit represented by the formula (A) will be shown.

[0039]Table 1

[0040]Among these, the repeating structural units represented by the above formulas (A-l), (A-2), (A-3), (A-4), and (A-5) are preferable.

[0041] Next, the above repeating structural unit represented by the formula (B) will be described. Hereinafter, specific examples of the above repeating structural unit represented by the formula (B) will be shown:

[0042]Among these, the repeating structural units represented by the above formulas (B-l), (B-2), (B-7), (B-8), (B-9), and (B-10) are preferable.

[0043] he polycarbonate resin A as the component a in the

present invention contains not less than 5% by mass and not more than 40% by mass of a siloxane moiety relative to the total mass of the polycarbonate resin A.

[0044] In the present invention, the siloxane moiety is a

moiety including silicon atoms on both ends that form a siloxane portion, a group boned to the silicon atoms, an oxygen atom, a silicon atom, and a group bonded thereto between the silicon atoms on the ends.

Specifically, in the present invention, the siloxane moiety refers to a moiety surrounded by the dashed line below in the case of the repeating structural unit represented by the following formula (A-S) : —hC—NH—(CH ₂ ) ₃ (CH ₂ ) ₃ -NH- (A-S)

[0045] Namely, the structural formula shown below is the

siloxane moiety:

Siloxane moiety

[0046] If the content of the siloxane moiety relative to the

total mass of the polycarbonate resin A as the

component a in the present invention is less than 5% by mass, a persistent reducing effect on the contact

stress cannot be sufficiently obtained, and the domain cannot be efficiently formed in the matrix including the components β and γ. If the content of the siloxane moiety is more than 40% by mass, the component yis aggregated in the domain including the component a, and the potential stability in repeating use cannot be sufficiently obtained.

[0047] The content of the siloxane moiety relative to the

total mass of the polycarbonate resin A as the

component a in the present invention can be analyzed by an ordinary analyzing method. Hereinafter, an example of the analyzing method will be shown.

[0048] First, the charge-transporting layer as the surface

layer of the electrophotographic photosensitive member is dissolved by a solvent. Subsequently, using an fractionating apparatus that can separate and recover each composition component such as a size exclusion chromatograph and a high performance liquid

chromatograph, a variety of materials contained in the charge-transporting layer as the surface layer

arefractionated. The fractionated polycarbonate resin

A as the component a is subjected to ¹ H-N R measurement. Using a conversion method using the peak position and the ratio of the peak area of the hydrogen atom

(hydrogen atom that forms the resin) obtained by the ■" ^■ H-NMR measurement, the structure and content of the material that forms the resin can be recognized. From those results, the number of repetitions of the

siloxane moiety and the molar ratio are calculated, and converted into the content (mass ratio) . Alternatively, the fractionated polycarbonate resin A as the component a is hydrolyzed in the presence of an alkali, and decomposed into a carboxylic acid portion and a

bisphenol portion. The obtained bisphenol portion is subjected to nuclear magnetic resonance spectrum

analysis or mass spectrometry. The number of

repetitions of the siloxane moiety and the molar ratio are calculated, and converted into the content (mass ratio) .

[0049] In the present invention, the mass ratio of the

siloxane moiety contained in the polycarbonate resin A as the component a was measured using the method above.

[0050] The polycarbonate resin A as the component a used in

the present invention is a copolymer of the repeating structural unit represented by the above formula (A) and the repeating structural unit represented by the above formula (B) . The form of copolymerization may be any form such as block copolymerization, random

copolymerization, and alternating copolymerization.

[0051] The weight-average molecular weight of the

polycarbonate resin A as the component a used in the present invention is preferably not less than 30,000 and not more than 150,000 from the viewpoint of

formation of the domain in the matrix containing the components β and γ. The weight-average molecular weight is more preferably not less than 40,000 and not more than 100,000.

[0052] In the present invention, the weight-average molecular weight of the resin is a weight-average molecular weight in terms of polystyrene measured by a method described in PTL 3 according to the standard method.

[0053] The polycarbonate resin A as the component a used in the present invention can be synthesized by the

conventional phosgene method, for example. The

polycarbonate resin A can also be synthesized by transesterification .

[0054 ] Hereinafter, a synthesis example of the polycarbonate resin A as the component a used in the present

invention will be shown.

[0055] The polycarbonate resin A can be synthesized by a

method described in PTL 2. In the present invention, using the same synthesis method, the component

a (polycarbonate resin A) shown in Synthesis Example in Table 2 was synthesized using materials corresponding to the above repeating structural unit represented by the formula (A) and those corresponding to the above repeating structural unit represented by the formula (B) . The weight-average molecular weight of the synthesized polycarbonate resin A and the content of the siloxane moiety of the polycarbonate resin A are shown in Table 2. [0056]Table 2

[0057] In the repeating structural unit example (A-l), the maximum number of repetitions "a" within the brackets was 43, and the minimum number thereof was 38. In the repeating structural unit example (A-6) , the maximum number of repetitions "a" within the brackets was 22, and the minimum number thereof was 18. In the

repeating structural unit example (A-8), the maximum number of repetitions "a" within the brackets was 210, and the minimum number thereof was 190.

[0058]<About component β>

The component β in the present invention is at least one resin selected from the polycarbonate resin C having the repeating structural unit represented by the following formula (C) and the polyester resin D having the repeating structural unit represented by the

wherein R ³¹ to R ³⁴ each independently represent a hydrogen atom or a methyl group; Y ² represents a single bond, a methylene group, an ethylidene group, a

propylidene group, a phenylethylidene group, a

cyclohexylidene group, or an oxygen atom;

wherein R ⁴¹ to R ⁴⁴ each independently represent a hydrogen atom or a methyl group; X represents a meta- phenylene group, a para-phenylene group, or a bivalent group having two para-phenylene groups bonded via an oxygen atom; Y ³ represents a single bond, a methylene group, an ethylidene group, a propylidene group, a cyclohexylidene group, or an oxygen atom.

] Hereinafter, specific examples of the above repeating structural unit represented by the formula (C) will be shown :

[0060]Among these, the repeating structural units represent* by the above formulas (C-l), (C-2), (C-7), (C-8), (C- and (C-10) are preferable.

[ 0061 ] Hereinafter, specific examples of the above repeating structural unit represented by the formula (D) will b

[0062]Among these, the repeating structural units represented by the above formulas (D-l), (D-2), (D-6), and (D-7) are preferable. Preferably, the β has no siloxane moiety from the viewpoint of formation of a uniform matrix with the charge-transporting substance.

[0063] The charge-transporting layer as the surface layer of the electrophotographic photosensitive member according to the present invention contains the components a and β as the resins, and another resin may be additionally mixed and used. Examples of the another resin that may be mixed and used include acrylic resins, polyester resins, and polycarbonate resins. In the case where another resin is mixed and used, the proportion of the component β to the another resin is preferably in the range of not less than 90% by mass to less than 100% by mass. In the present invention, in the case where another resin is mixed and used in addition to the component β (the polycarbonate resin C or the polyester resin D) , a resin having no siloxane structure is preferably used as the another resin from the viewpoint of formation of a uniform matrix with the charge- transporting substance.

[0064] The charge-transporting layer as the surface layer of the electrophotographic photosensitive member according to the present invention contains the component γ as the charge-transporting substance, and may contain a charge-transporting substance having a different structure. Examples of the charge-transporting

substance having a different structure that may be contained include triarylamine compounds and hydrazone compounds. Among these, use of the triarylamine compounds as the charge-transporting substance is preferable from the viewpoint of the potential

stability in repeating use. In the case where the charge-transporting substance other than the component γ is mixed and used, not less than 50% by mass of the component γ is preferably contained in all the charge- transporting substances contained in the charge- transporting layer. More preferably, not less than 70% by mass of the component γ is contained.

[0065]Next, a configuration of the electrophotographic

photosensitive member according to the present

invention will be described.

[0066] The electrophotographic photosensitive member according to the present invention is an electrophotographic photosensitive member including a conductive support, a charge-generating layer provided on the conductive support, and a charge-transporting layer provided on the charge-generating layer. In the

electrophotographic photosensitive member, the charge- transporting layer is the surface layer (topmost layer) of the electrophotographic photosensitive member.

[0067] The charge-transporting layer of the

electrophotographic photosensitive member according to the present invention contains the components α, β and γ·

[0068] he charge-transporting layer may have a laminate

structure. In this case, at least the charge- transporting layer on the topmost surface side has the matrix-domain structure.

[0069] As the electrophotographic photosensitive member,

usually, a cylindrical electrophotographic

photosensitive member obtained by forming a

photosensitive layer (charge-generating layer, charge- transporting layer) on a cylindrical conductive support is widely used; a belt-like or sheet-like

electrophotographic photosensitive member can be used.

[0070] [Conductive support]

As the conductive support used in the present invention, those having conductivity (conductive support) are preferable, and examples thereof include aluminum and aluminum alloys. In the case of an aluminum or

aluminum alloy conductive support, an ED tube, an EI tube, and those subjected to machining, electrochemical mechanical polishing, and wet or dry honing can be used. Examples of the conductive support also include those having a thin film of a conductive material such as aluminum, aluminum alloys, or indium oxide-tin oxide alloys on a metallic conductive support or a resin conductive support.

[0071] In order to suppress interference fringes, the surface of the conductive support is preferably roughened properly. Specifically, preferable is use of a

conductive support whose surface is subjected to honing, blasting, machining, or electropolishing or an aluminum or aluminum alloy conductive support having a

conductive layer containing a conductive metal-oxide particle and a resin on the conductive support. In order to suppress interference fringes produced in an output image by interference of the light reflected on the conductive layer surface, a surface roughening material for roughening the surface of the conductive layer can be added.

[0072] In the electrophotographic photosensitive member

according to the present invention, a conductive layer having a conductive particle and a resin may be

provided on the conductive support. By a method for forming the conductive layer having a conductive

particle and a resin on the conductive support, a powder containing a conductive particle in the

conductive layer is contained. Examples of the

conductive particle include carbon black, acetylene black, powders of metals such as aluminum, nickel, iron, nichrome, copper, zinc, silver, and powders of metal oxides such as conductive tin oxide and ITO.

[0073] Examples of the resin used for the conductive layer

include polyester resins, polycarbonate resins,

polyvinyl butyral resins, acrylic resins, silicone resins, epoxy resins, melamine resins, urethane resins, phenol resins, and alkyd resins. These resins may be used alone, or two or more thereof may be used in combination .

[0074] The conductive layer can be formed by dip coating or

solvent coating by a Meyer bar. Examples of a solvent for a coating solution for a conductive layer include ether solvents, alcohol solvents, ketone solvents, and aromatic hydrocarbon solvents.

[0075] The film thickness of the conductive layer is

preferably not less than 0.2 μιτι and not more than 40 μιτι, more preferably not less than 1 μπι and not more than 35 and still more preferably not less than 5 μκι and not more than 30 μιτι.

[0076] [Intermediate layer]

In the electrophotographic photosensitive member

according to the present invention, an intermediate layer may be provided between the conductive support or conductive layer and the charge-generating layer.

[0077] The intermediate layer can be formed as follows: a

coating solution for an intermediate layer containing a resin is applied onto the conductive layer, and dried or cured.

[0078] Examples of the resin used for the intermediate layer include polyacrylic acids, methyl cellulose, ethyl cellulose, polyamide resins, polyimide resins,

polyamidimide resins, polyamic acid resins, melamine resins, epoxy resins, and polyurethane resins. As the resin used for the intermediate layer, the

thermoplastic resins are preferable, and the

thermoplastic polyamide resins are preferable. As the polyamide resin, preferable are low crystalline or noncrystalline copolymerized nylons that can be applied in a solution state.

[0079] The film thickness of the intermediate layer is

preferably not less than 0.05 μπι and not more than 40 μπι, and more preferably not less than 0.1 μιη and not more than 7 um.

[0080] The intermediate layer may contain a semi-conductive

particle, an electron-transporting substance, or an electron receptive substance.

[0081] [Charge-generating layer]

In the electrophotographic photosensitive member

according to the present invention, a charge-generating layer is provided on the conductive support, the

conductive layer, or the intermediate layer.

[0082] Examples of the charge-generating substance used for

the electrophotographic photosensitive member according to the present invention include azo pigments,

phthalocyanine pigments, indigo pigments, and perylene pigments. One or two or more of these charge- generating substances may be used. Among these,

particularly preferable are oxytitanium phthalocyanine, hydroxy gallium phthalocyanine, and chlorogallium phthalocyanine for their high sensitivity.

[ 0083 ] Examples of the resin used for the charge-generating

layer include polycarbonate resins, polyester resins, butyral resins, polyvinyl acetal resins, acrylic resins, vinyl acetate resins, and urea resins. Among these, butyral resins are particularly preferable. These can be used alone, or two or more thereof can be mixed, or used as a copolymer.

[0084] The charge-generating layer can be formed as follows: a coating solution for a charge-generating layer obtained by dispersing the charge-generating substance, the resin, and a solvent is applied, and dried. The

charge-generating layer may be a deposited film of the charge-generating substance.

[0085] Examples of a dispersion method include methods using a homogenizer, an ultrasonic wave, a ball mill, a sand mill, an Attritor, and a roll mill.

[0086]As the proportion of the charge-generating substance to the resin, the charge-generating substance is preferably not less than 0.1 parts by mass and not more than 10 parts by mass, and particularly more preferably not less than 1 part by mass and not more than 3 parts by mass based on 1 part by mass of the resin.

[0087 ] Examples of the solvent used for the coating solution for a charge-generating layer include alcohol solvents, sulfoxide solvents, ketone solvents, ether solvents, ester solvents, and aromatic hydrocarbon solvents.

[0088] The film thickness of the charge-generating layer is

preferably not less than 0.01 μιιι and not more than 5 μιη, and more preferably not less than 0.1 urn and not more than 2 μπι.

[0089]A variety of sensitizers, antioxidants, ultraviolet

absorbing agents, and plasticizers can be added to the charge-generating layer when necessary. In order to prevent clogging of a flow of charges in the charge- generating layer, the charge-generating layer may contain an electron transport substance or an electron receptive substance.

[0090] [Charge-transporting layer]

In the electrophotographic photosensitive member

according to the present invention, a charge- transporting layer is provided on the charge-generating layer. The charge-transporting layer as the surface layer of the electrophotographic photosensitive member according to the present invention contains the

component γ as the specific charge-transporting

substance, and may contain a charge-transporting

substance having a different structure as described above. The charge-transporting substance having a different structure that may be mixed is as described above .

[0091] The charge-transporting layer as the surface layer of the electrophotographic photosensitive member according to the present invention contains the components aand β as the resin, and as described above, another resin may be mixed and used. The another resin that may be mixed and used is as described above.

[0092] The charge-transporting layer can be formed as follows: a coating solution for a charge-transporting layer obtained by dissolving the charge-transporting

substance and the respective resins in a solvent is applied, and dried.

[0093]As the proportion of the charge-transporting substance to the resin, the charge-transporting substance is preferably not less than 0.4 parts by mass and not more than 2 parts by mass, and more preferably not less than 0.5 parts by mass and not more than 1.2 parts by mass based on 1 part by mass of the resin.

[0094 ] Examples of the solvent used for the coating solution for a charge-transporting layer include ketone solvents, ester solvents, ether solvents, and aromatic

hydrocarbon solvents. These solvents may be used alone, or two or more thereof may be mixed and used. Among these solvents, use of ether solvents or aromatic hydrocarbon solvents is preferable from the viewpoint of solubility of the resin.

[0095] The film thickness of the charge-transporting layer is preferably not less than 5 urn and not more than 50 μιτι, and more preferably not less than 10 μιτι and not more than 35 μτα .

[0096]An antioxidant, an ultraviolet absorbing agent, a

plasticizer, and the like can be added to the charge- transporting layer when necessary.

[0097]A variety of additives can be added to the respective layers of the electrophotographic photosensitive member according to the present invention. Examples of the additives include deterioration preventing agents such as an antioxidant, an ultraviolet absorbing agent, a light stabilizer, and fine particles such as organic fine particles and inorganic fine particles. Examples of the deterioration preventing agents include hindered phenol antioxidants, hindered amine light stabilizers, sulfur atom-containing antioxidants, and phosphorus atom-containing antioxidants. Examples of the organic fine particles include polymer resin particles such as fluorine atom-containing resin particles, polystyrene fine particles, and polyethylene resin particles.

Examples of the inorganic fine particles include metal oxides such as silica and alumina.

[0098] In application of the coating solution for each layer, coating methods such as dip coating (immersion coating) , spray coating, spin coating, roller coating, Meyer bar coating, and blade coating can be used.

[0099] [Electrophotographic apparatus]

Fig. 1 shows an example of a schematic configuration of an electrophotographic apparatus including a process cartridge having the electrophotographic photosensitive member according to the present invention.

[0100] In Fig. 1, a cylindrical electrophotographic

photosensitive member 1 is rotated and driven around a shaft 2 in the arrow direction at a predetermined circumferential speed. The surface of the rotated and driven electrophotographic photosensitive member 1 is uniformly charged at a negative predetermined potential by a charging device 3 (such as a primary charging device: a charging roller) in a rotation process. Next, the surface of the electrophotographic photosensitive member 1 receives exposure light 4 (image exposure light) whose intensity is modulated according to a chronological electrical digital image signal of the information of a target image to be output from an exposing device such as slit exposure and laser beam scanning exposure (not shown) . Thus, an electrostatic latent image corresponding to the information of the target image is sequentially formed on the surface of the electrophotographic photosensitive member 1.

[0101] The electrostatic latent image formed on the surface of the electrophotographic photosensitive member 1 is developed by reversal development using a toner contained in a developer in a developing device 5.

Thus, a toner image is formed. Next, the toner image formed and carried on the surface of the

electrophotographic photosensitive member 1 is

sequentially transferred by the transfer bias from a transferring device 6 (such as a transfer roller) onto a transfer material P (such as paper) . The transfer material P is extracted from a transfer material feeding device (not shown) in synchronization with rotation of the electrophotographic photosensitive member 1, and fed between the electrophotographic photosensitive member 1 and the transferring device 6. A bias voltage having a polarity opposite to that the toner has is applied to the transferring device 6 from a bias power supply (not shown) .

[0102] The transfer material P having the transferred toner image thereon is separated from the surface of the electrophotographic photosensitive member 1, and conveyed to a fixing device 8. There, the toner image is fixed. Then, the transfer material P is conveyed to outside of the apparatus as an image formed product (print, copy) .

[0103] The surface of the electrophotographic photosensitive member 1 after toner image transfer is cleaned by a cleaning device 7 (such as a cleaning blade) by removing a transfer remaining developer (transfer remaining toner) . Next, the surface of the

electrophotographic photosensitive member 1 is

discharged by the exposure light (not shown) from the exposing device (not shown) , and repeatedly used to form an image. As shown in Fig. 1, the exposure is not always necessary if the charging device 3 is a contact charging device using a charging roller.

[0104] In the present invention, several components are selected from the electrophotographic photosensitive member 1, the charging device 3, the developing device 5, the transferring device 6 and the cleaning device 7, and the selected components may be accommodated in a container and integrally supported as a process

cartridge. Moreover, the process cartridge may be configured to be detachably attached to the main body of the electrophotographic apparatus such as a copier and a laser beam printer. In Fig. 1, the

electrophotographic photosensitive member 1, the charging device 3, the developing device 5 and the cleaning device 7 are integrally supported to form a cartridge, and the obtained process cartridge 9 is detachably attached to the main body of the

electrophotographic apparatus using a guiding device 10 such as a rail in the main body of the

electrophotographic apparatus.

Examples

[0105] Hereinafter, the present invention will be described more in detail using Examples and Comparative Examples. The present invention, however, will not be limited to Examples below. "Parts" in Examples means "parts by mass . "

[0106] Example 1

[0107] An aluminum cylinder having a diameter of 30 mm and a length of 260.5 mm was used as a conductive support. Next, a coating solution for a conductive layer was prepared using 10 parts of Sn0 ₂ -coated barium sulfate (conductive particle) , 2 parts of titanium oxide

(pigment for adjusting resistance) , 6 parts of a phenol resin, 0.001 parts of silicone oil (leveling agent), and a mixed solvent of 4 parts of methanol and 16 parts of methoxypropanol . The coating solution for a

conductive layer was applied onto the aluminum cylinder by dip coating, and thermally cured at 140°C for 30 minutes to form a conductive layer having a film thickness of 15

[0108] Next, 3 parts of N-methoxymethylated nylon and 3 parts of a copolymerized nylon were dissolved in a mixed solvent of 65 parts of methanol and 30 parts of n- butanol to prepare a coating solution for an

intermediate layer.

[0109] The coating solution for an intermediate layer was

applied onto the conductive layer by dip coating, and dried at 100°C for 10 minutes to form an intermediate layer having a film thickness of 0.7 μηα.

[0110] Next, 10 parts of hydroxy gallium phthalocyanine

(charge-generating substance) in crystals having strong peaks at Bragg angles (2Θ ± 0.2°) of 7.5°, 9.9°, 16.3°, 18.6°, 25.1°, and 28.3° in CuKa properties X ray

diffraction was prepared. To this, 250 parts of cyclohexanone and 5 parts of a polyvinyl butyral resin (trade name: S-LEC BX-1, made by Sekisui Chemical Co., Ltd.) was added. The mixed solution was dispersed under a 23 ± 3°C atmosphere for 1 hour by a sand mill using glass beads having a diameter of 1 mm. After dispersion, 250 parts of ethyl acetate was added to prepare a coating solution for a charge-generating layer. The coating solution for a charge-generating layer was applied onto the intermediate layer by dip coating, and dried at 100°C for 10 minutes to form a charge-generating layer having a film thickness of 0.26 μιτι.

[0111] Next, 10 parts of the charge-transporting substance having a structure represented by the above formula (1- 1) as the component γ, 4 parts of the polycarbonate resin A(l) synthesized in Synthesis Example 1 as the component a, and 6 parts of the polycarbonate resin C (weight-average molecular weight of 120,000) containing the repeating structure represented by the above formula (C-5) and the repeating structure represented by (C-7) in the ratio of 8:2 as the component β were dissolved in a mixed solvent of 20 parts of

tetrahydrofuran and 60 parts of toluene to prepare a coating solution for a charge-transporting layer.

[0112] he coating solution for a charge-transporting layer was applied onto the charge-generating layer by dip coating, and dried at 110°C for 1 hour to form a charge-transporting layer having a film thickness of 16 μτα. It was found that the formed charge-transporting layer contains the domain including the component a in the matrix including the components β and γ .

[0113] Thus, an electrophotographic photosensitive member

having the charge-transporting layer as the surface layer was produced. The components α, β , and γ

contained in the charge-transporting layer, the content of the siloxane moiety (siloxane content A) in the polycarbonate resin A, and the content of the siloxane moiety (siloxane content B) in the polycarbonate resin A based on the total mass of all the resins are shown in Table 3.

[0114] Next, evaluation will be described.

[0115] Evaluation was made about fluctuation of a bright

potential (potential fluctuation) when 2,000 sheets were repeatedly output, a relative value of an initial torque, a relative value of the torque when 2,000 sheets were repeatedly output, and observation of the surface of the electrophotographic photosensitive member at the time of measuring the torque.

[0116]As an evaluation apparatus, a laser beam printer LBP- 2510 made by Canon Inc. was modified such that a charged potential (dark potential) of the

electrophotographic photosensitive member might be adjusted, and used. A cleaning blade of a polyurethane rubber was set so as to have a contact angle of 22.5° and a contact pressure of 35 g/cm to the surface of the electrophotographic photosensitive member. Evaluation was made under an environment at a temperature of 23°C and a relative humidity of 50%.

[ 0117 ] <Evaluation of potential fluctuation>

The exposure amount (image exposure amount) of the laser light source at 780 nm in the evaluation

apparatus was set such that the light amount on the surface of the electrophotographic photosensitive member might be 0.3 μ.Ι/αΐΐ ² . The potentials of the surface of the electrophotographic photosensitive member (dark potential and bright potential) were measured at the position of the developing device while the developing device was replaced by a jig fixed such that a probe for measuring a potential might be located 130 mm from the end of the electrophotographic

photosensitive member. The dark potential of a non- exposed portion of the electrophotographic

photosensitive member was set at -450 V, and the bright potential photo-induced discharged from the dark potential by irradiation with laser light was measured. Using a plain paper of an A4 size, 2,000 sheets of an image were continuously output. The fluctuation amounts of the bright potential before and after the output were evaluated. A test chart having a printing ratio of 5% was used. The result is shown in the

Potential fluctuation of Table 8.

[0118] <Evaluation of relative value of torque>

On the same condition as the evaluation condition of the potential fluctuation, the driving current value (current value A) of a rotating motor for the

electrophotographic photosensitive member was measured. In the evaluation, the amount of contact stress between the electrophotographic photosensitive member and the cleaning blade was evaluated. The obtained current value indicates the amount of the contact stress between the electrophotographic photosensitive member and the cleaning blade.

[0119] Further, an electrophotographic photosensitive member for comparing the relative value of the torque was produced by the following method. An

electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the polycarbonate resin A(l) as the component a used for the charge-transporting layer of the

electrophotographic photosensitive member in Example 1 was replaced by the component β in Table 3, and only the component β was used as the resin. The

electrophotographic photosensitive member was used as the electrophotographic photosensitive member for comparison .

[0120] Using the produced electrophotographic photosensitive member for comparison, the driving current value

(current value B) of the rotating motor for the

electrophotographic photosensitive member was measured in the same manner as in Example 1.

[0121] The ratio of the driving current value (current value

A) of the electrophotographic photosensitive member containing the component a according to the present invention to the driving current value (current value

B) of the rotating motor for the electrophotographic photosensitive member without the component a was calculated. The obtained numeric value of (current value A) /(current value B) was compared as the relative value of the torque. The numeric value of the relative value of the torque indicates a degree of reduction in the amount of the contact stress between the

electrophotographic photosensitive member using the component a and the cleaning blade. As the numeric value of the relative value of the torque is smaller, the degree of reduction in the amount of the contact stress between the electrophotographic photosensitive member and the cleaning blade is higher. The result is shown in the Relative value of initial torque of Table 8. [0122] Subsequently, using a plain paper of an A4 size, 2,000 sheets of an image were continuously output. A test chart having a printing ratio of 5% was used. Then, the relative value of the torque after 2,000 sheets were repeatedly output was measured. The relative value of the torque after 2,000 sheets were repeatedly output was evaluated in the same manner as in the case of the relative value of the initial torque. In this case, 2,000 sheets were repeatedly output also in the electrophotographic photosensitive member for

comparison, and the relative value of the torque after 2,000 sheets were repeatedly output was calculated using the driving current value of the rotating motor at that time. The result is shown in the Relative value of torque after 2,000 sheets were repeatedly output in Table 8.

[0123] <Evaluation of matrix-domain structure>

In the electrophotographic photosensitive member produced by the method, a vertical cross section of the charge-transporting layer was observed using an ultrahigh depth shape measurement microscope VK-9500 (made by Keyence Corporation) . At that time, at a

magnification of an object lens of 50 times, a field of a 100-um square (10, 000 μιη ² ) of the surface of the electrophotographic photosensitive member was observed, the largest diameters of 100 formed domains selected at random in the visual field were measured. From the largest diameters, the average was calculated, and defined as a number average particle size. The results are shown in Table 8.

[0124] Examples 2 to 39

[0125] An electrophotographic photosensitive member was

produced in the same manner as in Example 1 except that the components α, β, and γ of the charge-transporting layer in Example 1 were replaced as shown in Table 3, and evaluated. It was found that in the formed charge- transporting layer, the domain including the component a is contained in the matrix including the components β and γ. The result is shown in Table 8.

[0126] The weight-average molecular weight of the

polycarbonate resin C used as the component β was as follows :

(C-5)/(C-7) = 8/2: 120,000

(C-l) : 100,000.

[0127] Examples 40 to 78

[0128]An electrophotographic photosensitive member was

produced in the same manner as in Example 1 except that the components α, β and γ of the charge-transporting layer in Example 1 were replaced as shown in Table 4, and evaluated. It was found that in the formed charge- transporting layer, the domain including the component a is contained in the matrix including the components β and γ. The result is shown in Table 8.

[0129] The weight-average molecular weight of the

polycarbonate resin C used as the component β was as follows :

(C-5)/(C-7) = 8/2: 120,000

(C-2) : 130,000

(C-3)/(C-5) = 3/7: 100,000.

[0130] Examples 79 to 117

[0131]An electrophotographic photosensitive member was

produced in the same manner as in Example 1 except that the components α, β and γ of the charge-transporting layer in Example 1 were replaced as shown in Table 5, and evaluated. It was found that in the formed charge- transporting layer, the domain including the component a is contained in the matrix including the components β and γ. The result is shown in Table 9.

[0132] The weight-average molecular weight of the

polycarbonate resin C used as the component β was as follows :

(C-6) / (C-7) = 8/2: 120, 000 (C-1)/(C-10) = 7/3: 130,000

(C-l) / (C-4) = 8/2: 120, 000

(C-l) / (C-8) = 8/2: 100,000

(C-l)/(C-9) = 8/2: 90,000.

[0133] Examples 118 to 156

[0134] An electrophotographic photosensitive member was

produced in the same manner as in Example 1 except that the components α, β and γ of the charge-transporting layer in Example 1 were replaced as shown in Table 6, and evaluated. It was found that in the formed charge- transporting layer, the domain including the component a is contained in the matrix including the components β and γ. The result is shown in Table 9. As the charge- transporting substance other than the component γ, a charge-transporting substance having the structure represented by the following formula (2-1) and the structure represented by the following formula (2-2) was mixed with a charge-transporting substance having a structure represented by the above formula (1) or the above formula (l ¹ ) as the component γ, and used:

[0135] The weight-average molecular weight of the polyester resin D used as the component β was as follows: (D-l) : 120, 000

(D-2) : 90, 000

(D-l) / (D-4) = 7/3: 130, 000

(D-2)/(D-3) = 9/1: 100,000

(D-5) : 100, 000

(D-7) : 110, 000.

[0136] The repeating structural units represented by the above formulas (D-l), (D-2), (D-3) , (D-4), and (D-5) each have the ratio of terephthalic acid/isophthalic acid of 1/1.

[0137] Comparative Examples 1 to 12

[0138] An electrophotographic photosensitive member was

produced in the same manner as in Example 1 except that the polycarbonate resin A(l) in Example 1 was replaced by polycarbonate resin (E(l): weight-average molecular weight of 60,000) containing the repeating structural unit represented by the above formula (A-l) and the repeating structural unit represented by the above formula (B-l) and having the content of the siloxane moiety of 2% by mass in a carbonate resin, and other changes were made as shown in Table 7. The

configuration of the resins contained in the charge- transporting layer and the content of the siloxane moiety are shown in Table 7. Evaluation was made in the same manner as in Example 1. The result is shown in Table 10. It was found that the formed charge- transporting layer has no matrix-domain structure.

[0139] Comparative Example 13

[0140]An electrophotographic photosensitive member was

produced in the same manner as in Example 1 except that unlike Example 1, only the polycarbonate resin E(l) was contained as the resin contained in the charge- transporting layer. The configuration of the resins contained in the charge-transporting layer and the content of the siloxane moiety are shown in Table 7. Evaluation was made in the same manner as in Example 1. The result is shown in Table 10. It was found that the formed charge-transporting layer has no matrix-domain structure. As the electrophotographic photosensitive member for comparing the relative value of the torque, the electrophotographic photosensitive member for comparison used in Example 1 was used.

[0141] Comparative Examples 14 to 25

[0142]An electrophotographic photosensitive member was

produced in the same manner as in Example 1 except that the polycarbonate resin A(l) in Example 1 was replaced by the polycarbonate resin (E(2): weight-average molecular weight of 70,000) containing the repeating structural unit represented by the above formula (A-l) and the repeating structural unit represented by the above formula (B-l) and having the content of the siloxane moiety of 50% by mass in the polycarbonate resin, and other changes were made as shown in Table 7. The configuration of the resins contained in the charge-transporting layer and the content of the siloxane moiety are shown in Table 7. Evaluation was made in the same manner as in Example 1. The result is shown in Table 10. In the charge-transporting layer, the matrix-domain structure was formed.

[0143] Comparative Example 26

[0144]An electrophotographic photosensitive member was

produced in the same manner as in Example 1 except that unlike Example 1, only the polycarbonate resin E(2) was contained as the resins contained in the charge- transporting layer. The configuration of the resins contained in the charge-transporting layer and the content of the siloxane moiety are shown in Table 7. Evaluation was made in the same manner as in Example 1. The result is shown in Table 10. It was found that the formed charge-transporting layer has no matrix-domain structure. As the electrophotographic photosensitive member for comparing the relative value of the torque, the electrophotographic photosensitive member for comparison used in Example 1 was used.

[0145] Comparative Example 27

[0146] The polycarbonate resin A(l) in Example 1 was replaced by the resin E(3) including the repeating structure described in PTL 2. The resin E(3) (weight-average molecular weight of 120,000) is a resin containing the repeating structural unit represented by the following formula (E-3) and the repeating structural unit

represented by the above formula (B-5) in a ratio of 10/90. The content of the siloxane moiety in the resin was 7% by mass. A coating solution for a charge- transporting layer was prepared as follows: 9 parts of the charge-transporting substance having the structure represented by the above formula (1-1) as the component γ, 6 parts of the polycarbonate resin E(3), and 1.2 parts of 1, 4-bis (dimethylsilyl) benzene were dissolved in a mixed solvent of 20 parts of tetrahydrofuran and 60 parts of toluene; to this, 0.04 parts of a platinum- cyclovinylmethylsiloxane complex

(cyclovinylmethylsiloxane solution containing 3 to 3.5% by weight of platinum atoms) was added as a catalyst. The coating solution for a charge-transporting layer was applied onto the charge-generating layer by dip coating, dried at 120°C for 2 hours, and subsequently dried under the condition of 1 mmHg for 12 hours.

Thereby, a charge-transporting layer including the charge-transporting substance and the crosslinked polycarbonate resin and having a film thickness of 16 μπι was formed. Other than this, an electrophotographic photosensitive member was produced in the same manner as in Example 1. The configuration of the resins contained in the charge-transporting layer and the content of the siloxane moiety are shown in Table 7. Evaluation was made in the same manner as in Example 1. The result is shown in Table 10. It was found that the formed charge-transporting layer has no matrix-domain structure. The numeric value of the number of

repetitions of the siloxane moiety in the repeating structural unit represented by the following formula (E-3) indicates the average of the number of

repetitions. In this case, the average of the number of repetitions of the siloxane moiety is 25 and 10 in the repeating structural unit represented by the

followin formula (E-3) in the resin E(3):

[0147] Comparative Example 28

[0148]An electrophotographic photosensitive member was

produced in the same manner as in Comparative Example 27 except that changes were made in Comparative Example 27 as shown in Table 7. The configuration of the

resins contained in the charge-transporting layer and the content of the siloxane moiety are shown in Table 7. Evaluation was made in the same manner as in Example 1. The result is shown in Table 10. It was found that the formed charge-transporting layer has no matrix-domain structure.

[0149] Comparative Examples 29 to 34

[0150]An electrophotographic photosensitive member was

produced in the same manner as in Example 1 except that the polycarbonate resin A(l) in Example 1 was replaced by the resin E(4) (weight-average molecular weight of 60,000) containing the repeating structural unit having the structure described in PTL 1, i.e., represented by the following formula (E-4) and the repeating

structural unit represented by the above formula (D-l) , and having the content of the siloxane moiety of 30% by mass in the resin, and other changes were made as shown in Table 7. The repeating structural unit represented by the following formula (E-4) and that represented by the above formula (D-l) have a ratio of terephthalic acid/isophthalic acid skeleton of 1/1. The

configuration of the resins contained in the charge- transporting layer and the content of the siloxane moiety are shown in Table 7. Evaluation was made in the same manner as in Example 1. The result is shown in Table 10. In the formed charge-transporting layer, the matrix-domain structure was formed. As the

electrophotographic photosensitive member for comparing the relative value of the torque, the

electrophotographic photosensitive member for

comparison used in Example 121 was used. The numeric value of the number of repetitions of the siloxane moiety in the repeating structural unit represented by the following formula (E-4) indicates the average of the number of repetitions. In this case, the average of the number of repetitions of the siloxane moiety is 40 in the repeating structural unit represented by the following formula (E-4) in the resin E(4):

[0151] Comparative Examples 35 to 38

[0152]An electrophotographic photosensitive member was

produced in the same manner as in Example 1 except that the polycarbonate resin A(l) in Example 1 was replaced by the resin E(4), the charge-transporting substance was replaced by that having the structure represented by the above formula (2-1), and other changes were made as shown in Table 7. The configuration of the resins contained in the charge-transporting layer and the content of the siloxane moiety are shown in Table 7. Evaluation was made in the same manner as in Example 1. The result is shown in Table 10. In the formed charge- transporting layer, the matrix-domain structure was formed. As the electrophotographic photosensitive member for comparing the relative value of the torque, the electrophotographic photosensitive member for comparison used in Example 121 was used.

[0153] Comparative Examples 39 and 40

[0154] An electrophotographic photosensitive member was

produced in the same manner as in Example 1 except that the polycarbonate resin A(l) in Example 1 was replaced by the polycarbonate resin A(2), the charge- transporting substance was replaced by that having the structure represented by the above formula (2-1), and other changes were made as shown in Table 7. The configuration of the resins contained in the charge- transporting layer and the content of the siloxane moiety are shown in Table 7. Evaluation was made in the same manner as in Example 1. The result is shown in Table 10. In the formed charge-transporting layer, the matrix-domain structure was formed. As the

electrophotographic photosensitive member for comparing the relative value of the torque, the

electrophotographic photosensitive member for

comparison used in Example 121 was used.

[0155] Comparative Examples 41 to 46

[0156] An electrophotographic photosensitive member was

produced in the same manner as in Example 1 except that the polycarbonate resin A(l) in Example 1 was replaced by the resin E(3), and other changes were made as shown in Table 7. Evaluation was made in the same manner as in Example 1. The result is shown in Table 10. In the formed charge-transporting layer, the matrix-domain structure was formed.

[0157 ] Comparative Example 47 [0158]An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that only the polycarbonate resin E(3) was contained as the resins contained in the charge-transporting layer. The configuration of the resins contained in the charge- transporting layer and the content of the siloxane moiety are shown in Table 7. Evaluation was made in the same manner as in Example 1. The result is shown in Table 10. It was found that the formed charge- transporting layer has no matrix-domain structure.

[0159]Table 3

0]Table 4

] Table 5

Mixing

Siloxane ratio of Siloxane

Component content component content w Component [a] Component [ β ]

A (% by [a] to B (% by mass ) component mass )

[β]

Example 79 (1-3) Resin A (1) 40 (C-6) / (C-7)=8/2 4/6 16

Example 80 (1-3) Resin A (1) 40 (C-6) / (C-7)=8/2 3/7 12

Example 81 (1-3) Resin A (1) 40 (C-6) / (C-7)=8/2 2/8 8

Example 82 (1-4) Resin A (2) 30 (C-6) / (C-7)=8/2 3/7 9

Example 83 (1-4) Resin A (2) 30 (C-6) / (C-7)=8/2 2/8 6

Example 84 (1-5) Resin A (3) 20 (C-6)/(C-7)=8/2 3/7 6

Example 85 (1-5) Resin A (3) 20 (C-6) / (C-7)=8/2 2/8 4

Example 86 (1-3) Resin A (4) 10 (C-l) / (C-10)=7/3 3/7 3

Example 87 (1-3) Resin A (4) 10 (C-l) / (C-10)=7/3 2/8 2

Example 88 (1-3) Resin A (5) 20 (C-l) / (C-4)=8/2 3/7 6

Example 89 (1-3) Resin A (6) 20 (C-l) / (C-4)=8/2 3/7 6

Example 90 (1-3) Resin A (7) 20 (C-l) / (C-4)=8/2 3/7 6

Example 91 (1-3) Resin A (8) 20 (C-l)/(C-4)=8/2 3/7 6

Example 92 (1-5) Resin A (9) 30 (C-l) / (C-10)=7/3 4/6 12

Example 93 (1-5) Resin A (9) 30 (C-l) / (C-10)=7/3 2/8 6

Example 94 (1-5) Resin A (10) 20 (C-l) / (C-10)=7/3 3/7 6

Example 95 (1-5) Resin A (10) 20 (C-l) / (C-10)=7/3 2/8 4

Example 96 (1-4) Resin A (11) 20 (C-l) / (C-4)=8/2 4/6 8

Example 97 (1-4) Resin A (11) 20 (C-l) / (C-4)=8/2 3/7 6

Example 98 (1-4) Resin A (12) 5 (C-l) / (C-4)=8/2 2/8 1

Example 99 (1-4) Resin A (13) 30 (C-l) / (C-4)=8/2 3/7 9

Example 100 (1-4) Resin A (13) 30 (C-l) / (C-4)=8/2 2/8 6

Example 101 (1-5) Resin A (14) 10 (C-l) / (C-8)=8/2 3/7 3

Example 102 (1-5) Resin A (14) 10 (C-l) / (C-8)=8/2 2/8 2

Example 103 (1-5) Resin A (15) 5 (C-l) / (C-8)=8/2 2/8 1

Example 104 (1-5) Resin A (16) 20 (C-l) /(C-8)=8/2 3/7 6

Example 105 (1-5) Resin A (16) 20 (C-l) / (C-8)=8/2 2/8 4

Example 106 (1-5) Resin A (17) 40 (C-l) /(C-8)=8/2 5/5 20

Example 107 (1-5) Resin A (17) 40 (C-l) / (C-8)=8/2 2/8 8

Example 108 (1-5) Resin A (18) 20 (C-l) / (C-8)=8/2 3/7 6

Example 109 (1-5) Resin A (18) 20 (C-l) / (C-8)=8/2 2/8 4

Example 110 (1-5) Resin A (19) 20 (C-l) / (C-9)=8/2 3/7 6

Example 111 (1-5) Resin A (19) 20 (C-l) / (C-9)=8/2 2/8 4

Example 112 (1-5) Resin A (20) 40 (C-l) / (C-9)=8/2 5/5 20

Example 113 (1-5) Resin A (20) 40 (C-l) / (C-9)=8/2 2/8 8

Example 114 (1-4) Resin A (21) 30 (C-6) / (C-7)=8/2 4/6 12

Example 115 (1-4) Resin A (22) 5 (C-6) / (C-7)=8/2 4/6 2

Example 116 (1-4) Resin A (23) 20 (C-6) / (C-7)=8/2 4/6 8

Example 117 (1-4) Resin A (24) 10 (C-6) / (C-7)=8/2 4/6 4 62] Table 6

Mixing

Component

Siloxane ratio of Siloxane [γ] /another content component content charge- Component [a] Component [β]

A ( % by [a] to B (% by transporting

mass ) component mass) substance

[β]

Example 118 (1-1) / (2-l)=8/2 Resin A (1) 40 (D-2) 4/6 16

Example 119 (1-1) / (2-l)=8/2 Resin A (1) 40 (D-2) 3/7 12

Example 120 (1-1) / (2-l)=8/2 Resin A (1) 40 (D-2) 2/8 8

Example 121 (1-1) / (2-l)=8/2 Resin A (2) 30 (D-l) 3/7 9

Example 122 (1-1) / (2-l)=8/2 Resin A (2) 30 (D-l) 2/8 6

Example 123 (1-1) / (2-l)=8/2 Resin A (3) 20 (D-l) 3/7 6

Example 124 (l-l)/(2-l)=8/2 Resin A (3) 20 (D-l) 2/8 4

Example 125 (1-1) / (2-l)=8/2 Resin A (4) 10 (D-l) / (D-4)=7/3 3/7 3

Example 126 (1-1) / (2-l)=8/2 Resin A (4) 10 (D-l) / (D-4)=7/3 2/8 2

Example 127 (1-1) / (2-l)=8/2 Resin A (5) 20 (D-l) / (D-4)=7/3 3/7 6

Example 128 (1-1) / (2-l)=8/2 Resin A (6) 20 (D-l) / (D-4)=7/3 3/7 6

Example 129 (1-1) / (2-l)=8/2 Resin A (7) 20 (D-l) / (D-4)=7/3 3/7 6

Example 130 (1-1) / (2-l)=8/2 Resin A (8) 20 (D-l) / (D-4)=7/3 3/7 6

Example 131 (1-1) / (2-l)=8/2 Resin A (9) 30 (D-2) / (D-3)=9/l 4/6 12

Example 132 (1-1) / (2-l)=8/2 Resin A (9) 30 (D-2) / (D-3)=9/l 2/8 6

Example 133 (1-1) / (2-l)=8/2 Resin A (10) 20 (D-2) / (D-3)=9/l 3/7 6

Example 134 (1-1) / (2-l)=8/2 Resin A (10) 20 (D-2) / (D-3)=9/l 2/8 4

Example 135 (1-1) / (2-l)=8/2 Resin A (11) 20 (D-2) 4/6 8

Example 136 (1-1) / (2-l)=8/2 Resin A (11) 20 (D-2) 3/7 6

Example 137 (1-1) / (2-l)=8/2 Resin A (12) 5 (D-2) 2/8 1

Example 138 (1-1) / (2-2)=8/2 Resin A (13) 30 (D-2) 3/7 9

Example 139 (1-1) / (2-2)=8/2 Resin A (13) 30 (D-2) 2/8 6

Example 140 (1-1) / (2-2)=8/2 Resin A (14) 10 (D-7) 3/7 3

Example 141 (1-1) / (2-2)=8/2 Resin A (14) 10 (D-7) 2/8 2

Example 142 (1-1) / (2-2)=8/2 Resin A (15) 5 (D-7) 2/8 1

Example 143 (1-1) / (2-2)=8/2 Resin A (16) 20 (D-7) 3/7 6

Example 144 (1-1) / (2-2)=8/2 Resin A (16) 20 (D-7) 2/8 4

Example 145 (1-1) / (2-l)=8/2 Resin A (17) 40 (D-7) 5/5 20

Example 146 (1-1) / (2-l)=8/2 Resin A (17) 40 (D-7) 2/8 8

Example 147 (1-1) / (2-l)=8/2 Resin A (18) 20 (D-5) 3/7 6

Example 148 (1-1) / (2-l)=8/2 Resin A (18) 20 (D-5) 2/8 4

Example 149 (1-1) / (2-l)=8/2 Resin A (19) 20 (D-5) 3/7 6

Example 150 (1-1) / (2-l)=8/2 Resin A (19) 20 (D-5) 2/8 4

Example 151 (1-1) / (2-l)=8/2 Resin A (20) 40 (D-7) 5/5 20

Example 152 (1-1) / (2-l)=8/2 Resin A (20) 40 (D-7) 2/8 8

Example 153 (1-1) / (2-2)=8/2 Resin A (21) 30 (D-7) 4/6 12

Example 154 (1-1) / (2-2)=8/2 Resin A (22) 5 (D-7) 4/6 2

Example 155 (1-1) / (2-2)=8/2 Resin A (23) 20 (D-7) 4/6 8

Example 156 (1-1) / (2-2)=8/2 Resin A (24) 10 (D-7) 4/6 4 ] he "Component [γ] " in Tables 3 to 6 means the

component γ contained in the charge-transporting layer. In the case where the charge-transporting substances are mixed and used, it means the kinds of the component γ and another charge-transporting substance and the mixing ratio thereof. The "Component [ a] " in Tables 3 to 6 means the configuration of the component a . The "Siloxane content A (% by mass) " in Tables 3 to 6 means the content of the siloxane moiety (% by mass) in the polycarbonate resin A. The "Component [ β ] " in Tables 3 to 6 means the configuration of the component β , and any resin thereof has no siloxane moiety. The "Mixing ratio of component [ a] to component [ β ] " in Tables 3 to 6 means the mixing ratio of the component a to the component β (component a/component β ) in the charge- transporting layer. The "Siloxane content B (% by mass) " in Tables 3 to 6 means the content of siloxane moiety (% by mass) in the polycarbonate resin A based on the total mass of the resins in the charge- transporting layer.

164]Table 7

[0165] The "Charge-transporting substance" in Table 7 means the charge-transporting substance contained in the charge-transporting layer. The proportion represents the mixing ratio of two components γ or the mixing ratio of component γ/another charge-transporting

substance. The "Resin" in Table 7 means the resin E or the polycarbonate resin A having a siloxane moiety.

The "Siloxane content A (% by mass)" in Table 7 means the content of the siloxane moiety (% by mass) in the "Resin". The "Component [ β ] " in Table 7 means the configuration of the component β . The "Mixing ratio of resin to component [ β ] " in Table 7 means the mixing ratio of the resin E or polycarbonate resin A to the component β (resin/component β ) in the charge- transporting layer. The "Siloxane content B (% by mass) " in Table 7 means the content of the siloxane moiety (% by mass) in the "Resin E" based on the total mass of all the resins in the charge-transporting layer.

[0166] Hereinafter, evaluation results of Examples 1 to 156

and Comparative Examples 1 to 47 are shown in Tables 8 to 10.

]Table 8

Relative value Relative value

Relative Relative

of torque after of torque after

Potential value of Particle Potential value of Particle

2,000 sheets 2,000 sheets fluctuation (V) initial size (nm) fluctuation (V) initial size (nm) are repeatedly are repeatedly torque torque

output output

Ex.1 10 0.68 0.74 420 Ex.40 13 0.68 0.74 420

Ex.2 8 0.70 0.75 330 Ex.41 12 0.70 0.75 330

Ex.3 5 0.72 0.77 260 Ex.42 10 0.72 0.77 260

Ex.4 8 0.65 0.70 400 Ex.43 8 0.63 0.68 370

Ex.5 5 0.68 0.73 300 Ex.44 8 0.65 0.70 270

Ex.6 5 0.68 0.73 300 Ex.45 10 0.65 0.70 270

Ex.7 5 0.68 0.73 260 Ex.46 10 0.68 0.73 260

Ex.8 5 0.70 0.77 220 Ex.47 8 0.70 0.77 220

Ex.9 5 0.70 0.78 200 Ex.48 5 0.70 0.78 200

Ex.10 5 0.72 0.78 380 Ex.49 5 0.72 0.78 380

Ex.11 8 0.70 0.80 350 Ex.50 13 0.70 0.80 350

Ex.12 8 0.72 0.78 420 Ex.51 13 0.72 0.78 420

Ex.13 5 0.68 0.77 370 Ex.52 10 0.65 0.70 320

Ex.14 10 0.65 0.70 590 Ex.53 10 0.62 0.68 540

Ex.15 8 0.68 0.74 540 Ex.54 10 0.65 0.70 490

Ex.16 8 0.70 0.77 550 Ex.55 12 0.68 0.75 500

Ex.17 5 0.70 0.79 510 Ex.56 10 0.70 0.79 510

Ex.18 10 0.68 0.74 580 Ex.57 13 0.68 0.74 580

Ex.19 8 0.70 0.75 530 Ex.58 13 0.70 0.75 530

Ex.20 5 0.72 0.80 470 Ex.59 10 0.72 0.80 470

Ex.21 10 0.65 0.71 610 Ex.60 13 0.65 0.71 610

Ex.22 13 0.65 0.70 630 Ex.61 15 0.62 0.68 610

Ex.23 10 0.68 0.73 550 Ex.62 15 0.68 0.73 550

Ex.24 10 0.70 0.74 500 Ex.63 15 0.70 0.74 500

Ex.25 10 0.68 0.76 550 Ex.64 15 0.65 0.73 500

Ex.26 15 0.63 0.68 670 Ex.65 20 0.63 0.68 670

Ex.27 13 0.65 0.70 650 Ex.66 18 0.65 0.70 650

Ex.28 10 0.73 0.80 250 Ex.67 13 0.70 0.75 200

Ex.29 5 0.75 0.85 230 Ex.68 8 0.75 0.85 230

Ex.30 5 0.78 0.86 240 Ex.69 8 0.78 0.86 240

Ex.31 5 0.78 0.88 220 Ex.70 5 0.78 0.88 220

Ex.32 5 0.83 0.88 180 Ex.71 8 0.83 0.88 180

Ex.33 5 0.85 0.90 150 Ex.72 5 0.85 0.90 150

Ex.34 8 0.80 0.85 220 Ex.73 13 0.80 0.85 220

Ex.35 5 0.83 0.89 200 Ex.74 10 0.83 0.89 200

Ex.36 25 0.62 0.67 760 Ex.75 28 0.62 0.67 760

Ex.37 20 0.65 0.71 610 Ex.76 25 0.65 0.71 610

Ex.38 30 0.62 0.69 740 Ex.77 30 0.62 0.69 740

Ex.39 25 0.65 0.70 670 Ex.78 28 0.65 0.70 670 able 9

Relative Relative value of value of

Relative Relative torque after torque after

Potential value of Particle Potential value of Particle

2,000 sheets 2,000 sheets fluctuation (V) initial size (nm) fluctuation (V) initial size (nm) are are torque torque

repeatedly repeatedly output output

Ex.79 10 0.65 0.70 450 Ex.118 15 0.70 0.73 380

Ex.80 8 0.68 0.72 360 Ex.119 13 0.72 0.75 290

Ex.81 5 0.70 0.75 290 Ex.120 10 0.75 0.78 220

Ex.82 8 0.62 0.65 430 Ex.121 13 0.65 0.70 360

Ex.83 5 0.65 0.68 330 Ex.122 10 0.70 0.75 260

Ex.84 5 0.65 0.70 330 Ex.123 10 0.68 0.70 260

Ex.85 5 0.68 0.73 290 Ex.124 8 0.68 0.73 220

Ex.86 5 0.72 0.75 250 Ex.125 10 0.72 0.78 190

Ex.87 5 0.72 0.75 230 Ex.126 8 0.75 0.82 170

Ex.88 5 0.75 0.80 380 Ex.127 10 0.78 0.80 320

Ex.89 8 0.72 0.75 350 Ex.128 15 0.75 0.80 290

Ex.90 8 0.75 0.78 450 Ex.129 13 0.78 0.82 390

Ex.91 5 0.70 0.75 400 Ex.130 10 0.75 0.80 340

Ex.92 8 0.68 0.73 620 Ex.131 13 0.70 0.72 570

Ex.93 8 0.70 0.73 570 Ex.132 13 0.72 0.75 520

Ex.94 5 0.68 0.73 550 Ex.133 10 0.72 0.75 500

Ex.95 5 0.68 0.73 510 Ex.134 10 0.72 0.78 460

Ex.96 10 0.65 0.70 580 Ex.135 13 0.70 0.75 530

Ex.97 8 0.68 0.73 530 Ex.136 13 0.72 0.75 480

Ex.98 5 0.70 0.75 440 Ex.137 10 0.75 0.82 390

Ex.99 8 0.68 0.70 600 Ex.138 13 0.72 0.75 540

Ex.100 13 0.68 0.73 610 Ex.139 18 0.70 0.75 550

Ex.101 10 0.70 0.75 580 Ex.140 15 0.72 0.77 520

Ex.102 10 0.72 0.75 520 Ex.141 13 0.75 0.82 460

Ex.103 8 0.70 0.75 570 Ex.142 13 0.72 0.77 520

Ex.104 15 0.65 0.70 670 Ex.143 20 0.65 0.68 620

Ex.105 13 0.68 0.70 670 Ex.144 15 0.68 0.75 620

Ex.106 8 0.75 0.78 280 Ex.145 13 0.75 0.80 220

Ex.107 5 0.78 0.83 250 Ex.146 10 0.80 0.85 190

Ex.108 5 0.80 0.83 250 Ex.147 10 0.82 0.85 190

Ex.109 5 0.80 0.85 240 Ex.148 8 0.82 0.90 180

Ex.110 5 0.80 0.85 210 Ex.149 10 0.83 0.90 140

Ex.111 5 0.83 0.88 180 Ex.150 10 0.85 0.90 110

Ex.112 8 0.83 0.88 250 Ex.151 13 0.85 0.87 180

Ex.113 5 0.85 0.90 230 Ex.152 8 0.87 0.90 160

Ex.114 22 0.65 0.68 760 Ex.153 28 0.65 0.68 700

Ex.115 20 0.68 0.73 630 Ex.154 25 0.68 0.75 570

Ex.116 28 0.65 0.70 770 Ex.155 30 0.65 0.68 710

Ex.117 22 0.68 0.73 700 Ex.156 28 0.70 0.72 640 [0169]Table 10

[0170] From the comparison of Examples with Comparative Examples 1 to 12, if the polycarbonate resin having the siloxane moiety in the charge-transporting layer has a low siloxane content, a reducing effect on the contact stress is not sufficiently obtained. This is shown by no reducing effect on the torque found in the initial torque and the torque after 2,000 sheets are repeatedly output in the evaluation method. In Comparative

Example 13, if the polycarbonate resin having the siloxane moiety has a low siloxane content, it is shown that increase in the content of the siloxane-containing resin in the charge-transporting layer does not lead to a sufficient relaxing effect on the contact stress.

[0171] From the comparison of Examples with Comparative

Examples 14 to 25, the polycarbonate resin having the siloxane moiety in the charge-transporting layer has a high siloxane content, the potential stability in repeating use are remarkably poor. In this case, while the matrix-domain structure is formed by the

polycarbonate resin having the siloxane moiety, the polycarbonate resin and the charge-transporting layer excessively contain the siloxane structure, leading to insufficient compatibility with the charge-transporting substance. For this reason, a sufficient potential stability in repeating use is not obtained. In

Comparative Example 26, the potential stability in repeating use is insufficient as well. In the result of Comparative Example 26, the matrix-domain structure is not formed, and large potential fluctuation occurs. Namely, in Comparative Examples 14 to 26, it is thought that compatibility with the charge-transporting

substance is insufficient in the case where the charge- transporting substance and the resin excessively containing the siloxane structure are contained.

[0172] From the comparison of Examples with Comparative

Examples 27 and 28, if the polycarbonate resin having the siloxane moiety in the charge-transporting layer has a crosslinking structure and does not form the matrix-domain structure, a relaxing effect on the contact stress is not sufficiently obtained.

From the comparison of Examples with Comparative

Examples 29 to 34, the potential stability may be poor in the charge-transporting substance shown in the present invention even if the matrix-domain structure is formed using the resin having the siloxane structure. Moreover, the comparison of Examples with Comparative Examples 29 to 34 shows that use of the polycarbonate resin according to the present invention improves the potential stability in repeating use. In this case, it also shows that in Examples, a sufficient potential stability can be compatible with a persistent relaxing effect on the contact stress. In Comparative Examples 29 to 34, the component γ having high compatibility with the resin in the charge-transporting layer

contains a large amount of the charge-transporting substance in the domain of the siloxane-containing resin. As a result, the charge-transporting substance is aggregated in the domain, leading to insufficient potential stability. In Examples, however, it is thought that the content of the charge-transporting substance in the domain is reduced because the

compatibility of the component a with the component γ in the present invention is low. For this reason, it is thought that the content of the charge-transporting substance in the domain that causes the potential fluctuation is reduced, and high potential stability is demonstrated. The results of Comparative Examples 35 to 40 also suggest that the compatibility of the

component a with the component γ improves the potential stability in repeating use. From the comparison of Comparative Examples 29 to 34 with Examples, in the case where the charge-transporting layer containing the components a and γ according to the present invention is formed, a remarkable suppressing effect on the potential fluctuation is obtained.

[0174] he comparison of Examples with Comparative Examples 41 to 46 shows that the potential stability is

insufficient if the siloxane moiety has an aryl group in the case where the matrix-domain structure is formed using the polycarbonate resin having the siloxane moiety in the charge-transporting layer. The result of Comparative Example 47 shows that the potential

stability in repeating use is insufficient if the siloxane moiety has an aryl group even in the case where the charge-transporting substance and the resin having a proper amount of the siloxane structure are contained.

[0175] While the present invention has been described with

reference to exemplary embodiments, it is to be

understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest

interpretation so as to encompass all such

modifications and equivalent structures and functions.

[0176] This application claims the benefit of Japanese Patent Application No. 2010-231812, filed October 14, 2010, which is hereby incorporated by reference herein in its entirety .