Electrophotographic photoreceptor for contact charging based on DC voltage, process cartridge, and image forming apparatus

Abstract

The invention relates to a direct current voltage-based electrophotographic photoreceptor for contact charging, a process cartridge, and an image forming apparatus. The electrophotographic photoreceptor for contact charging includes: a conductive substrate; the lower coating layer is arranged on the conductive substrate; the charge generation layer is arranged on the lower coating layer; the charge transmission layer is arranged on the charge generation layer; and a surface protection layer provided on the charge transport layer, the surface protection layer being a cured film of a composition containing a reactive charge transport material and having a hydroxyl group and a benzene ring structure, and the value of the peak surface area of the hydroxyl group / the peak surface area of the benzene ring structure in a total reflection measurement method by infrared spectroscopic analysis being more than 0.05 and 0.36 or less.

Description

Technical Field

[0001] The present invention relates to an electronic photographic photosensitive body, a processing box and an image forming device for contact charging based on direct current voltage. Background Art

[0002] Patent document 1 discloses an electronic photographic photoreceptor having at least one photosensitive layer on a conductive support, wherein at least the outermost layer of the photosensitive layer is made of a cross-linked cured film formed by a compound (I) having a plurality of substituents represented by the following general formula (A) and a compound (II) having a plurality of substituents represented by the following general formula (B), wherein the residual OH group content ratio A defined by the following formula (1) of the cross-linked cured film is less than 2.0, and the residual OH group content ratio B defined by the following formula (2) is less than 0.3.

[0003] General formula (A)

[0004] FD-Si(R 1 ) (3-a) (OR 2 ) a

[0005] (Wherein, F represents the photoelectric characteristic subunit, D represents the flexible subunit, R 1 represents a hydrogen atom, an alkyl group, or a substituted or unsubstituted aryl group, R 2 represents a hydrogen atom, an alkyl group, or a trialkylsilyl group, and a represents an integer of 1 to 3.

[0006] General formula (B)

[0007] -Si(R 3 ) (3-b) (OR 4 ) b

[0008] (Where R 3 represents a hydrogen atom, an alkyl group, or a substituted or unsubstituted aryl group, R 4 represents a hydrogen atom, an alkyl group, or a trialkylsilyl group, and b represents an integer of 1 to 3.

[0009] A=x1 / y……(1)

[0010] B=x2 / y……(2)

[0011] (Wherein, x1 represents the 3500-3300 cm-1 range based on OH stretching vibration -1 The absorbance of the infrared absorption peak under x2 is 955-890cm based on OH stretching vibration. -1 The absorbance of the infrared absorption peak under y represents the 1740-1700cm-1 of the carbonyl bond based on CO stretching vibration.-1 The absorbance of the infrared absorption peak below. )

[0012] Patent Document 1: Japanese Patent Application Publication No. 2000-314980 Summary of the invention

[0013] The object of the present invention is to provide an electronic photographic photosensitive body for contact charging based on a direct current voltage, that is, an electronic photographic photosensitive body for contact charging based on a direct current voltage having excellent wear suppression and image blur suppression properties, compared with a case where the value of the peak surface area of ​​the hydroxyl group / the peak surface area of ​​the benzene ring structure in the total reflection measurement method of infrared spectroscopy is less than 0.05 or exceeds 0.36 when the electronic photographic photosensitive body having a conductive substrate, an undercoat layer, a charge generating layer, a charge transport layer and a surface protective layer is subjected to contact charging by a direct current voltage and the surface protective layer is a cured film of a composition containing a reactive charge transport material.

[0014] Specific means for solving the above-mentioned problems include the following aspects.

[0015] <1> An electronic photographic photosensitive body for contact charging based on direct current voltage, comprising: a conductive substrate; an undercoat layer disposed on the conductive substrate; a charge generating layer disposed on the undercoat layer; a charge transport layer disposed on the charge generating layer; and a surface protective layer disposed on the charge transport layer, wherein the surface protective layer is a cured film of a composition containing a reactive charge transport material and has a hydroxyl group and a benzene ring structure, and the value of the peak surface area of ​​the hydroxyl group / the peak surface area of ​​the benzene ring structure in the total reflection measurement method of infrared spectroscopy analysis is greater than 0.05 and less than 0.36.

[0016] <2> The electrophotographic photoreceptor for contact charging by direct current voltage according to <1>, wherein

[0017] The surface protection layer is a cured film of a composition including a compound having a hydroxyl group and a compound having no hydroxyl group but having a benzene ring structure.

[0018] <3> The electrophotographic photoreceptor for contact charging by direct current voltage according to <2>, wherein

[0019] The compound having the hydroxyl group is the reactive charge transport material.

[0020] <4> The electrophotographic photoreceptor for contact charging by direct current voltage according to <2> or <3>, wherein

[0021] The compound having a hydroxyl group is a compound having a triallylamine structure.

[0022] <5> The electrophotographic photoreceptor for contact charging by direct current voltage according to any one of <2> to <4>, wherein

[0023] The compound having no hydroxyl group but having a benzene ring structure is a compound having a triallylamine structure.

[0024] <6> The electrophotographic photoreceptor for contact charging by direct current voltage according to any one of <2> to <5>, wherein

[0025] The value of the mass ratio MH / MB of the content MH of the compound having a hydroxyl group and the content MB of the compound having no hydroxyl group and having a benzene ring structure in the composition is 5 or more and 20 or less.

[0026] <7> The electrophotographic photoreceptor for contact charging by direct current voltage according to any one of <1> to <6>, wherein

[0027] The surface protection layer does not have a carboxyl group.

[0028] <8> The electrophotographic photoreceptor for contact charging by direct current voltage according to any one of <1> to <7>, wherein

[0029] The surface protection layer does not have silicon atoms.

[0030] <9> A process cartridge comprising the electrophotographic photoreceptor for contact charging by direct current voltage according to any one of <1> to <8>, wherein

[0031] The process cartridge is attached to and detached from an image forming apparatus, and performs contact charging on the electrophotographic photoreceptor by a DC voltage.

[0032] <10> An image forming device, comprising: an electrophotographic photosensitive body for contact charging based on a DC voltage as described in any one of <1> to <8>; a charging device for contact charging the surface of the electrophotographic photosensitive body by a DC voltage; an electrostatic latent image forming device for forming an electrostatic latent image on the charged surface of the electrophotographic photosensitive body; a developing device for developing the electrostatic latent image formed on the surface of the electrophotographic photosensitive body by a developer containing a colorant to form a toner image; and a transfer device for transferring the toner image to the surface of a recording medium.

[0033] Effects of the Invention

[0034] According to the invention involved in <1> or <2>, there is provided an electrophotographic photosensitive body for contact charging based on direct current voltage, which has a conductive substrate, an undercoat layer, a charge generating layer, a charge transport layer and a surface protective layer, and when the surface protective layer is a cured film of a composition containing a reactive charge transport material and is contact-charged by direct current voltage, the value of the peak surface area of ​​hydroxyl group / peak surface area of ​​benzene ring structure in the total reflection measurement method of infrared spectroscopy is 0.05 or less or exceeds 0.36, and the electrophotographic photosensitive body is excellent in wear suppression and image blur suppression.

[0035] According to the invention of <3>, there is provided an electrophotographic photoreceptor for contact charging by direct current voltage having better wear suppression and image blur suppression than when the reactive charge transport material is a compound having only a benzene ring structure and not having the hydroxyl group.

[0036] According to the invention of <4>, there is provided an electrophotographic photoreceptor for contact charging by direct current voltage having better wear suppression and image blur suppression than when the compound having a hydroxyl group is a compound having a mono / or diallylamine structure instead of a triallylamine structure.

[0037] According to the invention described in <5>, there is provided an electrophotographic photoreceptor for contact charging by direct current voltage having better wear suppression and image blur suppression than when the compound having no hydroxyl group but having a benzene ring structure is a compound having no triallylamine structure but having a mono / or diallylamine structure.

[0038] According to the invention involved in <6>, there is provided an electronic photographic photosensitive body for contact charging based on DC voltage, which has better wear inhibition and image blur inhibition than the case where the mass ratio MH / MB of the content MH of the compound having a hydroxyl group to the content MB of the compound having a benzene ring structure without a hydroxyl group in the composition is less than 5 or exceeds 20.

[0039] According to the invention as set forth in <7>, there is provided an electrophotographic photoreceptor for contact charging by direct current voltage, which has superior wear suppression performance and image blur suppression performance compared to the case where the surface protective layer has a carboxyl group.

[0040] According to the invention as set forth in <8>, there is provided an electrophotographic photoreceptor for contact charging by direct current voltage, which has better wear suppression performance and image blur suppression performance than when the surface protective layer has silicon atoms.

[0041] According to the invention involved in <9> or <10>, there is provided an electronic photographic photosensitive body which is contact-charged by a DC voltage and has a conductive substrate, an undercoat layer, a charge generating layer, a charge transport layer and a surface protective layer, wherein the surface protective layer is a cured film of a composition containing a reactive charge transport material, and the value of the peak surface area of ​​the hydroxyl group / the peak surface area of ​​the benzene ring structure in the total reflection measurement method of infrared spectroscopy is 0.05 or less or exceeds 0.36, and the processing box or image forming device is excellent in wear suppression and image blur suppression. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Embodiments of the present invention will be described in detail with reference to the following drawings.

[0043] Figure 1 is a schematic partial cross-sectional view showing an example of a layer structure of an electrophotographic photoreceptor according to the present embodiment;

[0044] Figure 2 is a schematic structural diagram showing an example of an image forming apparatus according to the present embodiment;

[0045] Figure 3 It is a schematic configuration diagram showing another example of the image forming apparatus according to the present embodiment.

[0046] Explanation of symbols

[0047] 1-undercoat layer, 2-charge generating layer, 3-charge transporting layer, 4-conductive substrate, 5-surface protective layer, 7A, 7-electrophotographic photoreceptor, 8-charging device, 9-exposure device, 11-developing device, 13-cleaning device, 14-lubricant, 40-transfer device, 50-intermediate transfer body, 100-image forming device, 120-image forming device, 131-cleaning blade, 132-fibrous component (roller-shaped), 133-fibrous component (flat brush-shaped), 300-processing box. DETAILED DESCRIPTION

[0048] Hereinafter, this embodiment will be described. These descriptions and examples are for illustrative purposes only and do not limit the scope of the embodiment.

[0049] In the present specification, a numerical range expressed using "to" indicates a range including the numerical values ​​described before and after "to" as the minimum value and the maximum value, respectively.

[0050] In the numerical ranges recorded in this specification, the upper limit or lower limit recorded in one numerical range may be replaced by the upper limit or lower limit of the numerical range recorded in other stages. In addition, in the numerical ranges recorded in this specification, the upper limit or lower limit of the numerical range may be replaced by the value shown in the embodiment.

[0051] In the present specification, the word "step" is included in this term as long as the intended purpose of the step can be achieved not only in an independent step but also in a case where the step cannot be clearly distinguished from other steps.

[0052] In this specification, each component may also include a plurality of corresponding substances. In this specification, when the amount of each component in the composition is mentioned, when there are a plurality of substances corresponding to each component in the composition, unless otherwise specified, it represents the total amount of the plurality of substances present in the composition.

[0053] In this specification, the main component refers to a main component. For example, the main component refers to a component that accounts for 30% by mass or more of the total mass of a mixture of multiple components.

[0054] (Electrophotographic photoreceptor for contact charging by direct current voltage)

[0055] The electronic photographic photoreceptor for contact charging based on direct current voltage involved in this embodiment (hereinafter also referred to as "electronic photographic photoreceptor" or "photoreceptor") has a conductive substrate, an undercoat layer arranged on the conductive substrate, a charge generating layer arranged on the undercoat layer, a charge transport layer arranged on the charge generating layer, and a surface protection layer arranged on the charge transport layer, wherein the surface protection layer is a cured film of a composition containing a reactive charge transport material, and has a hydroxyl group and a benzene ring structure, and the value of the peak surface area of ​​the hydroxyl group / the peak surface area of ​​the benzene ring structure in the total reflection measurement method of infrared spectroscopy analysis is greater than 0.05 and less than 0.36.

[0056] In the existing electronic photographic photosensitive body having a surface protective layer on the outermost surface in order to maintain the quality for a long time, when contact charging based on DC voltage is performed, if the surface protective layer is hardened, it will become difficult to wear, but the amount of attached discharge products scraped off will be reduced and the defect of image blur will be easily generated, so the wear will exceed a certain level, making it difficult to achieve both wear suppression and image blur suppression.

[0057] In the electronic photographic photosensitive body for contact charging based on DC voltage involved in this embodiment, the value of the peak surface area of ​​hydroxyl groups / peak surface area of ​​benzene ring structure in the total reflection measurement method of infrared spectroscopy analysis of the surface protective layer is greater than 0.05 and less than 0.36, thereby cross-linking reduces the hydroxyl groups in the surface protective layer, improves the hardness, reduces wear, and has fewer hydrophilic groups, namely hydroxyl groups, thereby inhibiting the adhesion of water to the surface of the electronic photographic photosensitive body, inhibiting the water from combining with the discharge products and adhering to the surface of the electronic photographic photosensitive body, reducing the amount of discharge product adhesion, and inhibiting the generation of image blur caused by water and discharge products, thereby presuming that the wear inhibition and image blur inhibition are excellent.

[0058] Hereinafter, the layer structure of the electrophotographic photoreceptor according to the present embodiment will be described with reference to the drawings.

[0059] Figure 1 It is a schematic cross-sectional view showing an example of the layer structure of the electrophotographic photoreceptor according to the present embodiment.

[0060] Figure 1 The photoreceptor 7A shown has a structure in which an undercoat layer 1, a charge generating layer 2, a charge transport layer 3, and a surface protective layer 5 are sequentially stacked on a conductive substrate 4. The charge generating layer 2 and the charge transport layer 3 constitute a photosensitive layer. The surface protective layer 5 is a cured film of a composition containing a reactive charge transport material, and has a hydroxyl group and a benzene ring structure, and the value of the peak surface area of ​​the hydroxyl group / the peak surface area of ​​the benzene ring structure in the total reflection measurement method of infrared spectroscopy analysis is more than 0.05 and less than 0.36.

[0061] In the electrophotographic photoreceptor according to the present embodiment, Figure 1 The photosensitive layer of the photoreceptor 7A shown is a functional separation type photosensitive layer in which the charge generating layer 2 and the charge transporting layer 3 are separated. In addition, the electrophotographic photoreceptor may further include layers other than these layers.

[0062] Hereinafter, the electrophotographic photoreceptor according to the present embodiment will be described layer by layer.

[0063] <Surface protection layer>

[0064] The surface protection layer is disposed on the charge transport layer.

[0065] The surface protection layer is a cured film of a composition containing a reactive charge transport material having a reactive group and a charge transport skeleton in the same molecule.

[0066] The surface protection layer has a hydroxyl group and a benzene ring structure, and the value of the peak surface area of ​​the hydroxyl group / the peak surface area of ​​the benzene ring structure in total reflection measurement by infrared spectroscopy is more than 0.05 and less than 0.36.

[0067] The surface protective layer has a hydroxyl group. The hydroxyl group may be an alcoholic hydroxyl group (= a hydroxyl group directly bonded to an aliphatic group) or a phenolic hydroxyl group (= a hydroxyl group directly bonded to an aromatic group), but the surface protective layer preferably has an alcoholic hydroxyl group, for example, from the viewpoint that the nucleophilicity of the hydroxyl group is high and the amount of the hydroxyl group present is further reduced.

[0068] The surface protection layer has a benzene ring structure. The substituent on the benzene ring is not particularly limited, and the benzene rings may be bonded to each other, such as a biphenyl structure.

[0069] The surface protection layer has a hydroxyl group and a benzene ring structure, and the value of the peak surface area of ​​the hydroxyl group / the peak surface area of ​​the benzene ring structure in the total reflection measurement method (ATR method) of infrared spectroscopy analysis (FT-IR analysis) is greater than 0.05 and less than 0.36. From the viewpoint of wear inhibition and image blur inhibition, for example, it is preferably greater than 0.07 and less than 0.36, more preferably greater than 0.10 and less than 0.30, and particularly preferably greater than 0.12 and less than 0.25.

[0070] The value of the peak surface area of ​​the hydroxyl group / the peak surface area of ​​the benzene ring structure in the total reflection measurement method of infrared spectroscopy was measured by the method shown below.

[0071] Infrared spectroscopy conditions

[0072] Device: Frontier manufactured by PerkinElmer

[0073] ATR crystal: Ge

[0074] Resolution: 4cm -1

[0075] Scan times: 32 times

[0076] The spectra were ATR corrected.

[0077] -Peak position-

[0078] OH group: 3450cm -1

[0079] Baseline: from 3705cm -1 Up to 3257cm -1 to draw.

[0080] Benzene ring structure: 820cm -1

[0081] Baseline: from 882cm -1 Up to 776cm -1 to draw.

[0082] Calculate the area of ​​the site enclosed by the baseline.

[0083] The OH group region area / benzene ring structure region area was used as an index of the amount of residual OH groups.

[0084] The surface protection layer is a layer composed of a cured film of a composition containing a reactive charge transport material having a reactive group and a charge transport skeleton in the same molecule (ie, a layer containing a polymer or a crosslinked body of the reactive charge transport material).

[0085] Furthermore, the surface protection layer may further contain a non-reactive charge transport material.

[0086] Examples of the reactive group of the reactive charge transport material include a chain polymerizable group, an epoxy group, -OH, -OR [wherein R represents an alkyl group.], -NH2, -SH, -COOH, -SiR Q1 3-Qn (OR Q2 ) Qn 〔Among them, R Q1 represents a hydrogen atom, an alkyl group, or a substituted or unsubstituted aryl group, R Q2 represents a hydrogen atom, an alkyl group, or a trialkylsilyl group. Qn represents an integer of 1 to 3. 〕 and the like. In addition, examples of the reactive groups in the non-charge transport material containing a reactive group include the above-mentioned known reactive groups.

[0087] As a chain polymerizable group, there is no particular limitation as long as it is a functional group capable of free radical polymerization, and for example, it is a functional group having a group containing at least a carbon double bond. Specifically, there can be mentioned a group containing at least one selected from vinyl, vinyl ether, vinyl sulfide, styryl, acryloyl, methacryloyl and their derivatives. Among them, due to its excellent reactivity, as a chain polymerizable group, for example, it is preferably a group containing at least one selected from vinyl, styryl (vinyl phenyl), acryloyl, methacryloyl and their derivatives.

[0088] Among them, the reactive group of the reactive charge transport material is preferably a chain polymerizable group, an epoxy group, -OH, -OR, -NH2 or -SH, more preferably -OH, -OR, -NH2 or -SH, further preferably -OH or -OR, and particularly preferably -OH, from the viewpoint of wear inhibition and image blur inhibition.

[0089] The charge transport skeleton is not particularly limited as long as it is a known structure in the image retainer, and examples thereof include skeletons derived from nitrogen-containing hole transport compounds such as triallylamine compounds (compounds having a triallylamine skeleton), benzidine compounds (compounds having a benzidine skeleton), and hydrazone compounds (compounds having a hydrazone skeleton) and structures conjugated with nitrogen atoms. Among them, from the viewpoints of charge transport, wear suppression, and image blur suppression, for example, as the charge transport skeleton, it is preferred to include a triallylamine skeleton.

[0090] The reactive charge transport material, the non-reactive charge transport material, and the reactive non-charge transport material having these reactive groups and charge transport skeletons may be selected from known materials.

[0091] The reactive charge transport material may be a reactive charge transport material having a hydroxyl group as a reactive group (hereinafter also referred to as “specific reactive charge transport material (a)”). The reactive non-charge transport material may be used alone or in combination of two or more.

[0092] As the specific reactive charge transport material (a), from the viewpoint of excellent charge transport properties, for example, a compound represented by the following formula (A) is preferred.

[0093] [Chemical formula 1]

[0094]

[0095] In the formula (A), Ar 1 To Ar 4 Each independently represents a substituted or unsubstituted aryl group, Ar 5 represents a substituted or unsubstituted aryl group or a substituted or unsubstituted arylene group, D represents an organic group having a hydroxyl group, c1 to c5 each independently represent an integer greater than or equal to 0 and less than or equal to 2, k represents 0 or 1, d represents an integer greater than or equal to 0 and less than or equal to 5, e represents 0 or 1, and the total number of D is greater than or equal to 4.

[0096] In the formula (A), Ar 1 To Ar 4 Each independently represents a substituted or unsubstituted aryl group. 1 To Ar 4 They can be the same or different.

[0097] Here, as the substituent in the substituted aryl group, D: a group other than an organic group having a hydroxyl group may include an alkyl group or alkoxy group having 1 to 4 carbon atoms, and a substituted or unsubstituted aryl group having 6 to 10 carbon atoms.

[0098] As Ar 1 To Ar 4 , for example, preferably any one of the following formulas (1) to (7). In addition, the following formulas (1) to (7) collectively represent the ability to be combined with Ar 1 To Ar 4 The respective links of "-(D) C1 " to "-(D) C4 "-(D) C ” are shown together.

[0099] [Chemical formula 2]

[0100]

[0101] -Ar-(Z') s -Ar-(D)c (7)

[0103] In the formulas (1) to (7), R 1 represents one selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a phenyl group substituted with an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms, an unsubstituted phenyl group, an aralkyl group having 7 to 10 carbon atoms, and a halogen atom, and R 2 To R 4 Each independently represents one selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a phenyl group substituted with an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms, an unsubstituted phenyl group, an aralkyl group having 7 to 10 carbon atoms, and a halogen atom, Ar represents a substituted or unsubstituted arylene group, D represents an organic group having a hydroxyl group, c represents 1 or 2, s represents 0 or 1, and t represents an integer of 0 to 3.

[0104] Here, Ar in the formula (7) is preferably represented by, for example, the following structural formula (8) or (9).

[0105] [Chemical formula 3]

[0106]

[0107] In the above formulas (8) and (9), R 5 and R 6 Each independently represents one selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a phenyl group substituted by an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms, an unsubstituted phenyl group, an aralkyl group having 7 to 10 carbon atoms, and a halogen atom, and t' each independently represents an integer of 0 to 3.

[0108] In the formula (7), Z' represents a divalent organic linking group, and is preferably a group represented by any one of the following formulae (10) to (17). In the formula (7), s represents 0 or 1.

[0109] [Chemical formula 4]

[0110]

[0111] In the formulas (10) to (17), R 7 and R 8Each of "a" and "b" independently represents one selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a phenyl group substituted with an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms, an unsubstituted phenyl group, an aralkyl group having 7 to 10 carbon atoms, and a halogen atom, W represents a divalent group, q and r each independently represent an integer of 1 to 10, and t" each independently represents an integer of 0 to 3.

[0112] As W in the above formulae (16) to (17), for example, any of the divalent groups represented by the following formulae (18) to (26) is preferred. In the formula (25), u represents an integer of 0 or more and 3 or less.

[0113] [Chemical formula 5]

[0114]

[0115] Furthermore, in formula (A), when k is 0, Ar 5 is a substituted or unsubstituted aryl group, and examples of the aryl group include 1 To Ar 4 Also, when k is 1, Ar 5 represents a substituted or unsubstituted arylene group, and examples of the arylene group include those consisting of 1 To Ar 4 The aryl group exemplified in the description of 3- (D) C3 )(Ar 4- (D) C4 ) is an arylene group having a hydrogen atom substituted at the position.

[0116] The content of the reactive charge transport material is preferably 30% by mass or more and 100% by mass or less, more preferably 40% by mass or more and 100% by mass or less, and further preferably 50% by mass or more and 100% by mass or less relative to the composition (solid content) used when forming the surface protection layer. By setting it within this range, the electrical properties of the cured film are excellent, and the cured film can be thickened.

[0117] Examples of non-reactive charge transport materials include quinone compounds such as p-benzoquinone, chloranil, tetrabromobenzoquinone, and anthraquinone; tetracyanoterephthalene compounds; fluorenone compounds such as 2,4,7-trinitrofluorenone; anthrone compounds; benzophenone compounds; cyanoethylene compounds; and electron transport compounds such as vinyl compounds. Examples of charge transport materials include hole transport compounds such as triarylamine compounds, benzidine compounds, arylalkyl compounds, aryl-substituted vinyl compounds, stilbene compounds, anthracene compounds, and hydrazone compounds. The non-reactive charge transport materials may be used alone or in combination of two or more.

[0118] Among them, as the non-reactive charge transport material, triallylamine compounds can be cited from the viewpoint of wear suppression and image blur suppression.

[0119] From the viewpoint of abrasion inhibition and image blur inhibition, the surface protective layer is, for example, preferably a cured film of a composition comprising a compound having a hydroxyl group and a compound having a benzene ring structure but not having a hydroxyl group, and more preferably a cured film of a composition comprising a compound having a hydroxyl group and a benzene ring structure and a compound having a benzene ring structure but not having a hydroxyl group.

[0120] From the viewpoint of wear suppression and image blur suppression, the compound having a hydroxyl group is preferably, for example, a reactive charge transport material having a reactive group and a charge transport skeleton, and more preferably a reactive charge transport material having a hydroxyl group and a charge transport skeleton.

[0121] Furthermore, from the viewpoints of charge transport properties, wear suppressing properties, and image blur suppressing properties, the compound having a hydroxyl group is preferably a compound having a triallylamine structure, for example.

[0122] From the viewpoint of wear suppression and image blur suppression, the compound having a benzene ring structure without the hydroxyl group is preferably a reactive charge transport material having a reactive group and a charge transport skeleton, and more preferably a reactive charge transport material having an alkoxy group and a charge transport skeleton.

[0123] From the viewpoint of charge transport properties, wear suppression properties, and image blur suppression properties, the compound having a benzene ring structure without having the hydroxyl group is preferably a compound having a triallylamine structure, for example.

[0124] From the viewpoint of abrasion suppression and image blur suppression, the value of the mass ratio MH / MB of the content MH of the compound having a hydroxyl group and the content MB of the compound having no hydroxyl group but having a benzene ring structure in the composition forming the cured film is, for example, preferably 2 or more and 30 or less, more preferably 3 or more and 25 or less, further preferably 5 or more and 20 or less, and particularly preferably 5 or more and 10 or less.

[0125] From the viewpoint of improving the image blur suppression property by reducing the hygroscopicity, the surface protection layer preferably has no carboxyl group, for example.

[0126] Furthermore, from the viewpoint of improving the abrasion suppression property and reducing the hygroscopicity to suppress the image blurring, the surface protection layer preferably has no silicon atom, and more preferably has no carboxyl group and no silicon atom, for example.

[0127] Examples of the reactive non-charge transport material include thermosetting resins, curing agents, etc. The reactive group-containing non-charge transport material may be used alone or in combination of two or more.

[0128] Examples of the thermosetting resin include guanamine resin, melamine resin, phenol resin, urea resin, and alkyd resin.

[0129] Examples of the curing agent include compounds having a guanamine structure (hereinafter, also referred to as “guanamine compounds”), compounds having a melamine structure (hereinafter, also referred to as “melamine compounds”), and the like.

[0130] When the surface protective layer is, for example, a cured film that is composed of a crosslinked body (crosslinked product) containing a reactive charge transport material and at least one selected from the group consisting of a thermosetting resin (for example, more preferably a guanamine resin, a melamine resin, etc.), a guanamine compound and a melamine compound, it is easier to obtain a cured film with a high degree of curing, and the wear inhibition property is better, compared with a case where it does not contain a thermosetting resin (for example, more preferably a guanamine resin, a melamine resin, etc.), a guanamine compound and a melamine compound.

[0131] The surface protective layer may further contain fluororesin particles.

[0132] When fluororesin particles are further contained, roughness is appropriately formed on the outer peripheral surface of the surface protection layer, and the wear suppressing property is further improved.

[0133] The surface protective layer contains fluororesin particles in an amount of 5 mass % or more and 15 mass % or less based on the total solid content of the surface protective layer.

[0134] The content of the fluororesin particles is, for example, preferably 5 mass % or more and 15 mass % or less, and more preferably 7 mass % or more and 12 mass % or less, based on the total constituent components of the layer (total solid content).

[0135] The fluororesin particles are not particularly limited, but examples thereof include particles of polytetrafluoroethylene (PTFE, also known as "tetrafluoroethylene resin"), perfluoroalkoxy fluororesin, polychlorotrifluoroethylene, polyvinylidene fluoride, polydichlorodifluoroethylene, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-ethylene copolymer, tetrafluoroethylene-hexafluoropropylene-perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene-perfluoroalkoxyethylene copolymer, and the like.

[0136] Among them, from the viewpoint of the wear suppression property and the cleaning property of the electrophotographic photoreceptor, for example, polytetrafluoroethylene and a copolymer of tetrafluoroethylene and perfluoroalkoxyethylene are preferred.

[0137] The fluororesin particles may be used alone or in combination of two or more.

[0138] The weight average molecular weight of the fluororesin constituting the fluororesin particles is preferably, for example, 3,000 to 5,000,000.

[0139] The average primary particle size of the fluororesin particles is, for example, preferably 0.05 μm or more and 10 μm or less, and more preferably 0.1 μm or more and 5 μm or less.

[0140] The average primary particle size of the fluororesin particles is a value measured using a laser diffraction / scattering particle size distribution analyzer LA-920 (manufactured by HORIBA, Ltd.) at a refractive index of 1.35 on a measurement solution diluted in the same solvent as the dispersion in which the fluororesin particles are dispersed.

[0141] Examples of commercially available fluororesin particles include Luberon (registered trademark) series (manufactured by Daikin Industries, Ltd.), Teflon (registered trademark) series (manufactured by DuPont), and Dyneon series (manufactured by 3M Japan Limited).

[0142] -Method for forming a surface protective layer-

[0143] The formation of the surface protective layer is not particularly limited and can be performed by a known formation method, but is preferably performed by, for example, forming a coating film of a surface protective layer-forming coating liquid (= the composition) in which the above-mentioned components are added to a solvent, drying the coating film, and performing a curing treatment such as heating as necessary.

[0144] From the viewpoint of coating film strength, abrasion suppression and image blur suppression, the drying temperature during coating film drying is, for example, preferably 150°C or higher, more preferably 150°C or higher and 200°C or lower, further preferably 150°C or higher and 180°C or lower, and particularly preferably 155°C or higher and lower than 170°C.

[0145] In addition, the drying time when the coating is dried is also related to the drying temperature, but from the viewpoint of coating strength, wear inhibition and image blur inhibition, it is preferably 10 minutes or more, more preferably 20 minutes or more, further preferably 20 minutes or more and 120 minutes or less, and particularly preferably 20 minutes or more and 60 minutes or less.

[0146] As the solvent used for preparing the coating liquid for forming the surface protective layer, there can be mentioned aromatic solvents such as toluene and xylene; ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; ester solvents such as ethyl acetate and butyl acetate; ether solvents such as tetrahydrofuran and dioxane; cellosolve solvents such as ethylene glycol monomethyl ether; alcohol solvents such as isopropyl alcohol and butanol, etc. These solvents can be used alone or in combination of two or more.

[0147] The content of the solvent is, for example, preferably 30% by mass to 95% by mass, more preferably 50% by mass to 90% by mass, and particularly preferably 60% by mass to 80% by mass, based on the total mass of the surface protection layer-forming coating liquid.

[0148] Examples of a method for applying the coating liquid for forming a surface protective layer onto a photosensitive layer (e.g., a charge transport layer) include common methods such as dip coating, push coating, wire bar coating, spray coating, blade coating, air knife coating, and curtain coating.

[0149] -Film thickness-

[0150] The film thickness of the surface protection layer is preferably set within the range of, for example, 1 μm to 20 μm, and more preferably within the range of 2 μm to 10 μm.

[0151] <Conductive substrate>

[0152] As the conductive substrate, for example, metal plates, metal drums and metal belts containing metals (aluminum, copper, zinc, chromium, nickel, molybdenum, vanadium, indium, gold, platinum, etc.) or alloys (stainless steel, etc.) can be cited. In addition, as the conductive substrate, for example, conductive compounds (such as conductive polymers, indium oxide, etc.); paper coated, vapor-deposited or laminated with metals (such as aluminum, palladium, gold, etc.) or alloys; resin films; belts, etc. Here, "conductive" means that the volume resistivity is less than 10 13 Ω·cm.

[0153] When the electrophotographic photoreceptor is used in a laser printer, the surface of the conductive substrate is preferably roughened to 0.04 μm or more and 0.5 μm or less in terms of center line average roughness Ra for the purpose of suppressing interference fringes generated when irradiating a laser beam. In addition, when incoherent light is used as a light source, roughening to prevent interference fringes is not particularly necessary, but the generation of defects caused by the unevenness of the conductive substrate surface is suppressed, so it is suitable for a longer life.

[0154] Examples of the roughening method include wet grinding in which an abrasive is suspended in water and sprayed onto the conductive substrate, centerless grinding in which the conductive substrate is pressed against a rotating grinding wheel and continuously ground, and anodizing.

[0155] As a method of roughening, there is also a method in which, without roughening the surface of the conductive substrate, conductive or semiconductive powder is dispersed in a resin to form a layer on the surface of the conductive substrate, and roughening is performed by particles dispersed in the layer.

[0156] The roughening treatment based on anodization is to use a metal (e.g., aluminum) conductive substrate as an anode and perform anodization in an electrolyte solution, thereby forming an oxide film on the surface of the conductive substrate. As an electrolyte solution, for example, sulfuric acid solution, oxalic acid solution, etc. can be cited. However, the porous anodized film formed by anodization is chemically active in its original state, easily contaminated, and the resistance change caused by the environment is also large. Therefore, for example, it is preferred that the porous anodized film is blocked by the volume expansion caused by water and reaction in pressurized steam or boiling water (metal salts such as nickel can be added.) The micropores of the oxide film are blocked to change to a more stable hydrated oxide sealing treatment.

[0157] The film thickness of the anodized film is preferably, for example, 0.3 μm or more and 15 μm or less. When the film thickness is within the above range, the barrier property against injection tends to function and the increase in residual potential due to repeated use tends to be suppressed.

[0158] The conductive substrate may be subjected to a treatment using an acidic treatment liquid or a boehmite treatment.

[0159] The treatment based on the acidic treatment solution is implemented, for example, in the following manner. First, an acidic treatment solution containing phosphoric acid, chromic acid and hydrofluoric acid is prepared. The proportion of phosphoric acid, chromic acid and hydrofluoric acid in the acidic treatment solution is, for example, in the range of 10 mass % to 11 mass % for phosphoric acid, in the range of 3 mass % to 5 mass % for chromic acid, and in the range of 0.5 mass % to 2 mass % for hydrofluoric acid, and the concentration of the total amount of these acids is preferably in the range of 13.5 mass % to 18 mass %. The treatment temperature is, for example, preferably 42° C. to 48° C. The film thickness of the film is, for example, preferably 0.3 μm to 15 μm.

[0160] The boehmite treatment is carried out, for example, by immersing in pure water at 90°C to 100°C for 5 to 60 minutes or contacting in heated water vapor at 90°C to 120°C for 5 to 60 minutes. The film thickness of the film is preferably 0.1 μm to 5 μm. An anodizing treatment can be further performed using an electrolyte solution with low film solubility such as adipic acid, boric acid, borate, phosphate, phthalate, maleate, benzoate, tartrate, or citrate.

[0161] <Undercoat>

[0162] The undercoat layer is, for example, a layer containing inorganic particles and a binder resin.

[0163] Examples of inorganic particles include powder resistance (volume resistivity) of 10 2 Ω·cm or more and 10 11 Inorganic particles with a particle size of less than Ω·cm.

[0164] Among them, as the inorganic particles having the above resistance value, for example, metal oxide particles such as tin oxide particles, titanium oxide particles, zinc oxide particles, and zirconium oxide particles are preferred, and zinc oxide particles are particularly preferred.

[0165] The specific surface area of ​​the inorganic particles based on the BET method is preferably 10 m 2 / g or above.

[0166] The volume average particle diameter of the inorganic particles is, for example, preferably 50 nm or more and 2,000 nm or less (for example, preferably 60 nm or more and 1,000 nm or less).

[0167] The content of the inorganic particles is, for example, preferably 10% by mass or more and 80% by mass or less, and more preferably 40% by mass or more and 80% by mass or less, based on the binder resin.

[0168] The inorganic particles may be subjected to surface treatment. Two or more inorganic particles having different surface treatments or particles having different particle sizes may be used in combination.

[0169] Examples of the surface treatment agent include silane coupling agents, titanate coupling agents, aluminum coupling agents, surfactants, etc. In particular, for example, a silane coupling agent is preferred, and a silane coupling agent having an amino group is more preferred.

[0170] Examples of the silane coupling agent having an amino group include, but are not limited to, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, and N,N-bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane.

[0171] Silane coupling agents can be mixed and used in two or more ways. For example, silane coupling agents with amino groups can be used in combination with other silane coupling agents. As other silane coupling agents, for example, vinyl trimethoxysilane, 3-methacryloxypropyl-tris (2-methoxyethoxy) silane, 2- (3,4-epoxycyclohexyl) ethyl trimethoxysilane, 3-glycidoxypropyl trimethoxysilane, vinyl triacetoxysilane, 3-mercaptopropyl trimethoxysilane, 3-aminopropyl triethoxysilane, N-2- (aminoethyl) -3-aminopropyl trimethoxysilane, N-2- (aminoethyl) -3-aminopropyl methyl dimethoxysilane, N, N-bis (2-hydroxyethyl) -3-aminopropyl triethoxysilane, 3-chloropropyl trimethoxysilane, etc. can be cited, but it is not limited thereto.

[0172] The surface treatment method using the surface treatment agent may be any method as long as it is a known method, and may be either a dry method or a wet method.

[0173] The treatment amount of the surface treatment agent is preferably, for example, 0.5% by mass or more and 10% by mass or less relative to the inorganic particles.

[0174] Here, from the viewpoint of improving the long-term stability of electrical characteristics and carrier blocking properties, the undercoat layer preferably contains an electron accepting compound (acceptor compound) together with inorganic particles, for example.

[0175] As electron accepting compounds, for example, there can be mentioned quinone compounds such as chloranil and tetrabromobenzoquinone; tetracyanobenzoquinone dimethane compounds; fluorenone compounds such as 2,4,7-trinitrofluorenone and 2,4,5,7-tetranitro-9-fluorenone; oxadiazole compounds such as 2-(4-biphenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole, 2,5-bis(4-naphthyl)-1,3,4-oxadiazole, and 2,5-bis(4-diethylaminophenyl)-1,3,4-oxadiazole; xanthone compounds; thiophene compounds; diphenoquinone compounds such as 3,3',5,5'-tetra-tert-butyldiphenoquinone; and other electron transporting substances.

[0176] In particular, the electron accepting compound is preferably a compound having an anthraquinone structure. The compound having an anthraquinone structure is preferably a hydroxyanthraquinone compound, an aminoanthraquinone compound, an aminohydroxyanthraquinone compound, and more specifically, anthraquinone, alizarin, quinizarin, anthraquinone, purpurin, and the like.

[0177] The electron accepting compound may be contained in the undercoat layer in a dispersed state together with the inorganic particles, or may be contained in the undercoat layer in a state of being attached to the surfaces of the inorganic particles.

[0178] Examples of a method for attaching the electron accepting compound to the surface of the inorganic particles include a dry method and a wet method.

[0179] The dry method is, for example, a method in which an electron accepting compound or an electron accepting compound dissolved in an organic solvent is directly added dropwise while stirring the inorganic particles by a mixer with a large shear force, and the electron accepting compound is sprayed together with dry air or nitrogen to attach the electron accepting compound to the surface of the inorganic particles. When the electron accepting compound is added dropwise or sprayed, for example, it can be done at a temperature below the boiling point of the solvent. After the electron accepting compound is added dropwise or sprayed, sintering can also be performed at a condition of 100°C or above. There is no particular limitation on the sintering temperature and time as long as the electrophotographic properties can be obtained.

[0180] The wet method is, for example, a method in which inorganic particles are dispersed in a solvent by stirring, ultrasonic waves, a sand mill, a grinder, a ball mill, etc., and after adding an electron accepting compound and stirring or dispersing, the solvent is removed to attach the electron accepting compound to the surface of the inorganic particles. The solvent removal method is, for example, to remove the solvent by filtering or distilling. After removing the solvent, sintering can also be performed at a condition of 100°C or above. Sintering is not particularly limited as long as the temperature and time are such that electronic photographic properties can be obtained. In the wet method, the water content of the inorganic particles can be removed before adding the electron accepting compound. As examples thereof, a method of removing the water content in the solvent while stirring and heating the water content, and a method of removing the water content by azeotropic reaction with the solvent can be cited.

[0181] The electron accepting compound may be attached before or after the inorganic particles are surface treated with a surface treatment agent, or the electron accepting compound may be attached and the surface treated with a surface treatment agent may be simultaneously performed.

[0182] The content of the electron accepting compound may be, for example, 0.01 mass % to 20 mass % inclusive, and preferably 0.01 mass % to 10 mass % inclusive, based on the inorganic particles.

[0183] Examples of the binder resin used in the lower coating layer include acetal resins (e.g., polyvinyl butyral), polyvinyl alcohol resins, polyvinyl acetal resins, casein resins, polyamide resins, cellulose resins, gelatin, polyurethane resins, polyester resins, unsaturated polyester resins, methacrylic resins, acrylic resins, polyvinyl chloride resins, polyvinyl acetate resins, vinyl chloride-vinyl acetate-maleic anhydride resins, silicone resins, silicone-alkyd resins, urea resins, phenolic resins, phenol-formaldehyde resins, melamine resins, urethane resins, alkyd resins, epoxy resins and other well-known polymer compounds; zirconium chelate compounds; titanium chelate compounds; aluminum chelate compounds; titanium alkoxide compounds; organic titanium compounds; silane coupling agents and other well-known materials.

[0184] Examples of the binder resin used in the undercoat layer include a charge transporting resin having a charge transporting group, and a conductive resin (for example, polyaniline).

[0185] Among them, the binding resin used in the lower coating layer is preferably a resin that is insoluble in the coating solvent in the upper layer, and is particularly preferably a resin obtained by reacting at least one resin selected from the group consisting of thermosetting resins such as urea resin, phenolic resin, phenol-formaldehyde resin, melamine resin, urethane resin, unsaturated polyester resin, alkyd resin, epoxy resin, polyamide resin, polyester resin, polyether resin, methacrylic resin, acrylic resin, polyvinyl alcohol resin and polyvinyl acetal resin with a curing agent.

[0186] When two or more of these binder resins are used in combination, the mixing ratio is set as necessary.

[0187] In order to improve electrical characteristics, improve environmental stability, and improve image quality, various additives may be included in the undercoat layer.

[0188] As additives, there can be mentioned known materials such as polycyclic condensation type, azo type and other electron transporting pigments, zirconium chelate compounds, titanium chelate compounds, aluminum chelate compounds, titanium alkoxide compounds, organic titanium compounds, silane coupling agents, etc. As mentioned above, silane coupling agents are used for surface treatment of inorganic particles, but can also be added to the undercoat layer as an additive.

[0189] Examples of the silane coupling agent as an additive include vinyltrimethoxysilane, 3-methacryloxypropyl-tris(2-methoxyethoxy)silane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, 3-mercaptopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N,N-bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane, and 3-chloropropyltrimethoxysilane.

[0190] Examples of the zirconium chelate compound include zirconium butoxide, zirconium ethyl acetoacetate, zirconium triethanolamine, zirconium acetylacetonate butoxide, zirconium ethyl acetoacetate butoxide, zirconium acetate, zirconium oxalate, zirconium lactate, zirconium phosphonate, zirconium octanoate, zirconium naphthenate, zirconium laurate, zirconium stearate, zirconium isostearate, zirconium methacrylate butoxide, zirconium stearate butoxide, and zirconium isostearate butoxide.

[0191] Examples of the titanium chelate compound include tetraisopropyl titanate, tetra-n-butyl titanate, butyl titanate dimer, tetra(2-ethylhexyl) titanate, titanium acetylacetonate, titanium polyacetylacetonate, titanium octanediol, ammonium lactate titanium, titanium lactate, ethyl lactate titanium, triethanolamine titanium, and polyhydroxystearate titanium.

[0192] Examples of the aluminum chelate compound include aluminum isopropoxide, monobutoxyaluminum diisopropoxide, aluminum butoxide, diethyl acetoacetate aluminum diisopropoxide, and tris(ethyl acetoacetate)aluminum.

[0193] These additives may be used alone or in the form of a mixture or polycondensate of a plurality of compounds.

[0194] The undercoat layer may have a Vickers hardness of 35 or more, for example.

[0195] In order to suppress interference moire images, the surface roughness (ten-point average roughness) of the undercoat layer is preferably adjusted to, for example, 1 / (4n) (n is the refractive index of the upper layer) to 1 / 2 of the exposure laser wavelength λ used.

[0196] In order to adjust the surface roughness, resin particles or the like may be added to the undercoat layer. Examples of the resin particles include silicone resin particles and cross-linked polymethacrylate methyl resin particles. In addition, in order to adjust the surface roughness, the surface of the undercoat layer may be ground. Examples of the grinding method include polishing, sandblasting, wet grinding, grinding, and the like.

[0197] The formation of the undercoat layer is not particularly limited and can be performed by a known formation method. For example, the undercoat layer can be formed by forming a coating film of an undercoat layer-forming coating liquid prepared by adding the above-mentioned components to a solvent, drying the coating film, and heating as necessary.

[0198] Examples of the solvent used for preparing the coating solution for forming an undercoat layer include known organic solvents such as alcohol solvents, aromatic hydrocarbon solvents, halogenated hydrocarbon solvents, ketone solvents, ketone alcohol solvents, ether solvents, and ester solvents.

[0199] Specific examples of these solvents include common organic solvents such as methanol, ethanol, n-propanol, isopropanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, ethyl acetate, n-butyl acetate, dioxane, tetrahydrofuran, dichloromethane, chloroform, chlorobenzene, and toluene.

[0200] Examples of a method for dispersing the inorganic particles when preparing the coating liquid for forming an undercoat layer include known methods such as a roll mill, a ball mill, a vibration ball mill, an attritor, a sand mill, a colloid mill, and a paint shaker.

[0201] Examples of a method for applying the coating liquid for forming an undercoat layer onto the conductive substrate include common methods such as blade coating, wire bar coating, spray coating, dip coating, bead coating, air knife coating, and curtain coating.

[0202] The film thickness of the undercoat layer is preferably set to, for example, 15 μm or more, and more preferably within the range of 20 μm or more and 50 μm or less.

[0203] <Middle layer>

[0204] Although not shown in the figure, an intermediate layer may be provided between the undercoat layer and the charge generating layer.

[0205] The intermediate layer is, for example, a layer containing a resin. Examples of the resin used in the intermediate layer include acetal resins (e.g., polyvinyl butyral), polyvinyl alcohol resins, polyvinyl acetal resins, casein resins, polyamide resins, cellulose resins, gelatin, polyurethane resins, polyester resins, methacrylic resins, acrylic resins, polyvinyl chloride resins, polyvinyl acetate resins, vinyl chloride-vinyl acetate-maleic anhydride resins, silicone resins, silicone-alkyd resins, phenol-formaldehyde resins, melamine resins and other polymer compounds.

[0206] The intermediate layer may be a layer containing an organic metal compound. Examples of the organic metal compound used in the intermediate layer include organic metal compounds containing metal atoms such as zirconium, titanium, aluminum, manganese, and silicon.

[0207] The compounds used in the intermediate layer may be used alone or as a mixture or polycondensate of a plurality of compounds.

[0208] Among them, the intermediate layer is preferably a layer containing an organic metal compound containing zirconium atoms or silicon atoms, for example.

[0209] The formation of the intermediate layer is not particularly limited and a known formation method can be used. For example, the intermediate layer can be formed by forming a coating film of an intermediate layer-forming coating liquid prepared by adding the above components to a solvent, drying the coating film, and heating as necessary.

[0210] As a coating method for forming the intermediate layer, a common method such as a dip coating method, a push coating method, a wire bar coating method, a spray coating method, a blade coating method, an air knife coating method, a curtain coating method, etc. can be used.

[0211] The film thickness of the intermediate layer is preferably set within a range of, for example, 0.1 μm or more and 3 μm or less.

[0212] <Charge Generation Layer>

[0213] The charge generating layer is, for example, a layer containing a charge generating material and a binder resin. Furthermore, the charge generating layer may be a vapor-deposited layer of the charge generating material. The vapor-deposited layer of the charge generating material is suitable for the case where an incoherent light source such as an LED (Light Emitting Diode) or an organic EL (Electro-Luminescence) image array is used.

[0214] Examples of the charge generating material include azo pigments such as disazo and trisazo; condensed ring aromatic pigments such as dibromoanthraquinone; perylene pigments; pyrrolopyrrole pigments; phthalocyanine pigments; zinc oxide; and trigonal selenium.

[0215] Among them, in order to cope with laser exposure in the near-infrared region, metal phthalocyanine pigments or metal-free phthalocyanine pigments are preferably used as charge generating materials, and more specifically, hydroxygallium phthalocyanine, chlorogallium phthalocyanine, dichlorotin phthalocyanine, and oxytitanium phthalocyanine are more preferred.

[0216] On the other hand, in order to cope with laser exposure in the near-ultraviolet region, preferred charge generating materials include condensed ring aromatic pigments such as dibromoanthraquinone, thioindigo pigments, porphyrazine compounds, zinc oxide, trigonal selenium, and disazo pigments.

[0217] The above-mentioned charge generating material can be used even when an incoherent light source such as an LED or an organic EL array having a central wavelength of light emitted in the range of 450 nm to 780 nm is used.

[0218] On the other hand, when an n-type semiconductor such as a condensed aromatic pigment, perylene pigment, or azo pigment is used as a charge generating material, dark current is less likely to be generated, and image defects called black spots can be suppressed even in a thin film.

[0219] The n-type is determined by using the commonly used time-of-flight method based on the polarity of the photocurrent flowing, and a semiconductor in which electrons flow more easily as carriers than holes is defined as the n-type.

[0220] The binder resin used in the charge generating layer can be selected from a wide range of insulating resins, and can be selected from organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinyl anthracene, polyvinyl pyrene, and polysilane.

[0221] Examples of the binder resin include polyvinyl butyral resin, polyarylate resin (condensation products of bisphenols and aromatic dicarboxylic acids), polycarbonate resin, polyester resin, phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyamide resin, acrylic resin, polyacrylamide resin, polyvinyl pyridine resin, cellulose resin, urethane resin, epoxy resin, casein, polyvinyl alcohol resin, polyvinyl pyrrolidone resin, etc. Here, "insulation" means that the volume resistivity is 10 13 Ω·cm or more.

[0222] These binder resins may be used alone or in combination of two or more.

[0223] The mixing ratio of the charge generating material to the binder resin is preferably in the range of 10:1 to 1:10, for example, in terms of mass ratio.

[0224] Other well-known additives may be contained in the charge generating layer.

[0225] The formation of the charge generating layer is not particularly limited, and a known formation method can be used, but for example, it can be performed by forming a coating film of a charge generating layer-forming coating liquid in which the above-mentioned components are added to a solvent, drying the coating film, and heating as needed. In addition, the charge generating layer can be formed by vapor deposition of the charge generating material. The formation of the charge generating layer by vapor deposition is particularly suitable for the case where a condensed ring aromatic pigment or a perylene pigment is used as the charge generating material.

[0226] Examples of the solvent used for preparing the charge generating layer-forming coating solution include methanol, ethanol, n-propanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, n-butyl acetate, dioxane, tetrahydrofuran, dichloromethane, chloroform, chlorobenzene, toluene, etc. These solvents may be used alone or in combination of two or more.

[0227] As a method for dispersing particles (e.g., charge generating material) in the coating liquid for forming the charge generating layer, for example, a medium disperser such as a ball mill, a vibrating ball mill, a grinder, a sand mill, a horizontal sand mill, or a stirrer, an ultrasonic disperser, a roll mill, a high-pressure homogenizer, or a medium-free disperser can be used. As a high-pressure homogenizer, for example, a collision method in which the dispersion is dispersed by liquid-liquid collision or liquid-wall collision under high pressure, and a penetration method in which the dispersion is dispersed by penetrating a fine flow path under high pressure, etc. can be cited.

[0228] In the dispersion, it is effective to set the average particle size of the charge generating material in the charge generating layer forming coating liquid to 0.5 μm or less, for example, preferably 0.3 μm or less, more preferably 0.15 μm or less.

[0229] Examples of a method for applying the charge generating layer forming coating liquid onto the undercoat layer (or the intermediate layer) include common methods such as blade coating, wire bar coating, spray coating, dip coating, bead coating, air knife coating, and curtain coating.

[0230] The film thickness of the charge generating layer is preferably set within the range of, for example, 0.1 μm to 5.0 μm, and more preferably within the range of 0.2 μm to 2.0 μm.

[0231] <Charge transport layer>

[0232] The charge transport layer is, for example, a layer containing a charge transport material and a binder resin. The charge transport layer may be a layer containing a polymer charge transport material.

[0233] As charge transport materials, there can be cited quinone compounds such as p-benzoquinone, chloranil, tetrabromobenzoquinone, anthraquinone, etc.; tetracyanoterephthalene compounds; fluorenone compounds such as 2,4,7-trinitrofluorenone; anthrone compounds; benzophenone compounds; cyanoethylene compounds; ethylene compounds and other electron transport compounds. As charge transport materials, there can also be cited hole transport compounds such as triarylamine compounds, benzidine compounds, arylalkane compounds, aryl-substituted ethylene compounds, stilbene compounds, anthracene compounds, hydrazone compounds, etc. These charge transport materials can be used alone or in combination of two or more, but are not limited thereto.

[0234] From the viewpoint of charge mobility, the charge transport material is preferably, for example, a triarylamine derivative represented by the following structural formula (a-1) and a benzidine derivative represented by the following structural formula (a-2).

[0235] [Chemical formula 6]

[0236]

[0237] In the structural formula (a-1), Ar T1 ,Ar T2 and Ar T3 Each independently represents a substituted or unsubstituted aryl group, -C6H4-C(R T4 )=C(R T5 )(R T6 ) or -C6H4-CH=CH-CH=C(R T7 )(R T8 ). T4 , R T5 , R T6 , R T7 and R T8 Each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group.

[0238] Examples of substituents of the above groups include halogen atoms, alkyl groups having 1 to 5 carbon atoms, and alkoxy groups having 1 to 5 carbon atoms. In addition, examples of substituents of the above groups include substituted amino groups substituted with alkyl groups having 1 to 3 carbon atoms.

[0239] [Chemical formula 7]

[0240]

[0241] In the structural formula (a-2), R T91 and R T92 R each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms. T101 , R T102 , R T111 and R T112 each independently represents a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an amino group substituted by an alkyl group having 1 to 2 carbon atoms, a substituted or unsubstituted aryl group, -C(R T12 )=C(R T13 )(R T14 ) or -CH=CH-CH=C(R T15 )(R T16 ), R T12 , R T13 , R T14 , R T15 and R T16 Each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group. Tm1, Tm2, ​​Tn1, and Tn2 each independently represent an integer of 0 or more and 2 or less.

[0242] Examples of substituents of the above groups include halogen atoms, alkyl groups having 1 to 5 carbon atoms, and alkoxy groups having 1 to 5 carbon atoms. In addition, examples of substituents of the above groups include substituted amino groups substituted with alkyl groups having 1 to 3 carbon atoms.

[0243] Here, from the viewpoint of charge mobility, among the triarylamine derivatives represented by the structural formula (a-1) and the benzidine derivatives represented by the structural formula (a-2), for example, those having "-C6H4-CH=CH-CH=C(R T7 )(R T8 )" and triarylamine derivatives having "-CH=CH-CH=C(R T15 )(R T16 )" benzidine derivatives.

[0244] As the polymer charge transport material, known materials having charge transport properties such as poly-N-vinyl carbazole and polysilane can be cited. In particular, polyester-based polymer charge transport materials are particularly preferred. The polymer charge transport material can be used alone or in combination with a binder resin.

[0245] The binder resin used in the charge transport layer can be polycarbonate resin, polyester resin, polyarylate resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinylidene chloride resin, polystyrene resin, polyvinyl acetate resin, styrene-butadiene copolymer, vinylidene chloride-acrylonitrile copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, silicone resin, silicone alkyd resin, phenol-formaldehyde resin, styrene-alkyd resin, poly-N-vinyl carbazole, polysilane, etc. Among them, as a binder resin, for example, preferably polycarbonate resin or polyarylate resin. These binder resins are used alone or in combination of two or more.

[0246] The mixing ratio of the charge transport material to the binder resin is preferably, for example, 10:1 to 1:5 in terms of mass ratio.

[0247] Other well-known additives may be contained in the charge transport layer.

[0248] The charge transport layer can be formed by any known method without particular limitation, but can be formed by, for example, forming a coating film of a charge transport layer-forming coating liquid prepared by adding the above components to a solvent, drying the coating film, and heating as necessary.

[0249] As the solvent for preparing the coating solution for forming the charge transport layer, there can be mentioned aromatic hydrocarbons such as benzene, toluene, xylene, and chlorobenzene; ketones such as acetone and 2-butanone; halogenated aliphatic hydrocarbons such as dichloromethane, chloroform, and dichloroethane; cyclic or linear ethers such as tetrahydrofuran and diethyl ether, and other common organic solvents. These solvents can be used alone or in combination of two or more.

[0250] Examples of a coating method for coating the charge transport layer-forming coating liquid on the charge generating layer include common methods such as blade coating, wire bar coating, spray coating, dip coating, bead coating, air knife coating, and curtain coating.

[0251] The film thickness of the charge transport layer is preferably set within the range of, for example, 5 μm to 50 μm, and more preferably within the range of 10 μm to 30 μm.

[0252] (Image Forming Apparatus (and Processing Cartridge))

[0253] The image forming apparatus according to the present embodiment comprises an electrophotographic photoreceptor, a charging device for contact charging the surface of the electrophotographic photoreceptor by direct current voltage, an electrostatic latent image forming device for forming an electrostatic latent image on the charged surface of the electrophotographic photoreceptor, a developing device for developing the electrostatic latent image formed on the surface of the electrophotographic photoreceptor by a developer containing a toner to form a toner image, and a transfer device for transferring the toner image to the surface of a recording medium. In addition, as the electrophotographic photoreceptor, the electrophotographic photoreceptor for contact charging by direct current voltage according to the present embodiment is applicable.

[0254] The image forming apparatus involved in this embodiment is applicable to the following well-known image forming apparatuses: a device equipped with a fixing component for fixing the toner image transferred to the surface of a recording medium; a device of a direct transfer method for directly transferring the toner image formed on the surface of an electrophotographic photosensitive body to the recording medium; a device of an intermediate transfer method for transferring the toner image formed on the surface of an electrophotographic photosensitive body once to the surface of an intermediate transfer body, and for a second time transferring the toner image transferred to the surface of the intermediate transfer body to the surface of a recording medium; a device equipped with a cleaning component for cleaning the surface of the electrophotographic photosensitive body after transferring the toner image but before charging; a device equipped with a static elimination component for removing static electricity by irradiating the surface of the electrophotographic photosensitive body with static elimination light after transferring the toner image and before charging; and a device equipped with an electrophotographic photosensitive body heating component for increasing the temperature of the electrophotographic photosensitive body and lowering the relative temperature, etc.

[0255] In the case of an intermediate transfer type device, the transfer unit, for example, is applicable to the following structure, which has an intermediate transfer body that transfers the toner image on the surface, a primary transfer unit that transfers the toner image formed on the surface of the electronic photographic photosensitive body to the surface of the intermediate transfer body for the first time, and a secondary transfer unit that transfers the toner image transferred to the surface of the intermediate transfer body to the surface of the recording medium for the second time.

[0256] The image forming apparatus according to the present embodiment may be any of a dry developing system image forming apparatus and a wet developing system (development system using a liquid developer) image forming apparatus.

[0257] In addition, in the image forming apparatus according to the present embodiment, for example, the portion having the electrophotographic photoreceptor may be a cartridge structure (processing cartridge) that is detachable from the image forming apparatus and that performs contact charging of the electrophotographic photoreceptor by a DC voltage. As the processing cartridge, for example, a processing cartridge having the electrophotographic photoreceptor for contact charging by a DC voltage according to the present embodiment is preferably used. In addition, in the processing cartridge, in addition to the electrophotographic photoreceptor, for example, at least one selected from the group consisting of a charging unit, an electrostatic latent image forming unit, a developing unit, and a transfer unit may be provided.

[0258] Hereinafter, an example of the image forming apparatus according to the present embodiment is shown, but the present invention is not limited thereto. In addition, the main parts shown in the drawings are described, and the description of other parts is omitted.

[0259] Figure 2 It is a schematic configuration diagram showing an example of the image forming apparatus according to the present embodiment.

[0260] like Figure 2 As shown, the image forming apparatus 100 according to the present embodiment includes a process cartridge 300 having an electrophotographic photoreceptor 7, an exposure device 9 (an example of an electrostatic latent image forming unit), a transfer device 40 (a primary transfer device), and an intermediate transfer body 50. In addition, in the image forming apparatus 100, the exposure device 9 is arranged at a position capable of exposing the electrophotographic photoreceptor 7 from the opening of the process cartridge 300, and the transfer device 40 is arranged at a position opposed to the electrophotographic photoreceptor 7 via the intermediate transfer body 50, and the intermediate transfer body 50 is arranged so that a part thereof contacts the electrophotographic photoreceptor 7. Although not shown in the figure, a secondary transfer device is further provided for transferring the toner image transferred to the intermediate transfer body 50 to a recording medium (e.g., paper). In addition, the intermediate transfer body 50, the transfer device 40 (a primary transfer device), and the secondary transfer device (not shown) correspond to an example of a transfer unit.

[0261] Figure 2The process box 300 in the embodiment integrally supports the electrophotographic photoreceptor 7, the charging device 8 (an example of a charging unit), the developing device 11 (an example of a developing unit), and the cleaning device 13 (an example of a cleaning unit) in the housing. The cleaning device 13 has a cleaning blade (an example of a cleaning member) 131, and the cleaning blade 131 is configured to contact the surface of the electrophotographic photoreceptor 7. In addition, the cleaning member may be a conductive or insulating fibrous member instead of the cleaning blade 131, and it may be used alone or in combination with the cleaning blade 131.

[0262] In addition, Figure 2 In the example shown, as the image forming apparatus, a fibrous member 132 (roller-shaped) for supplying lubricant 14 to the surface of electrophotographic photoreceptor 7 and a fibrous member 133 (flat brush-shaped) for assisting cleaning are provided, but these may be arranged as necessary.

[0263] Hereinafter, each structure of the image forming apparatus according to the present embodiment will be described.

[0264] -Electrified Devices-

[0265] As the charging device 8 , for example, a contact type charging device such as a charging roller using conductivity or semi-conductivity, a charging brush, a charging film, a charging rubber blade, or a charging hose can be used.

[0266] -Exposure device-

[0267] As the exposure device 9, for example, there can be cited an optical system device that exposes semiconductor laser, LED light, liquid crystal shutter light, etc. on the surface of the electrophotographic photoreceptor 7 to a prescribed pattern. The wavelength of the light source is set within the spectral sensitivity region of the electrophotographic photoreceptor. As the wavelength of the semiconductor laser, near-infrared light with an oscillation wavelength near 780nm is the mainstream. However, it is not limited to this wavelength. As an oscillation wavelength laser or a blue laser in the 600nm band, a laser with an oscillation wavelength in the range of more than 400nm and less than 450nm can also be used. In addition, a surface-emitting laser light source of the type that can output multiple beams in order to form a color image is also effective.

[0268] -Developing device-

[0269] As the developing device 11, for example, a general developing device that develops by contact or non-contact with a developer can be cited. As the developing device 11, there is no particular limitation as long as it has the above-mentioned function, and it can be selected according to the purpose. For example, a known developer having a function of attaching a single-component developer or a two-component developer to the electrophotographic photoreceptor 7 using a brush, a roller, etc. can be cited. Among them, for example, a developer using a developing roller that holds the developer on the surface is preferred.

[0270] The developer used in the developing device 11 may be a single-component developer containing only a toner, or may be a two-component developer containing a toner and a carrier. Furthermore, the developer may be magnetic or non-magnetic. As these developers, well-known developers are applicable.

[0271] -Cleaning device-

[0272] The cleaning device 13 may be a cleaning blade type device including a cleaning blade 131 .

[0273] In addition to the cleaning blade method, a brush cleaning method and a simultaneous development and cleaning method may also be used.

[0274] -Transfer device-

[0275] Examples of the transfer device 40 include a contact transfer charger using a belt, a roller, a film, a rubber blade, etc.; a corotron transfer charger using corona discharge; a corotron transfer charger, etc., which are known per se.

[0276] -Intermediate transfer body-

[0277] As the intermediate transfer body 50, a belt-shaped transfer body (intermediate transfer belt) made of polyimide, polyamideimide, polycarbonate, polyarylate, polyester, rubber, etc. imparted with semiconductivity can be used. In addition, as a form of the intermediate transfer body, a roller-shaped transfer body can be used.

[0278] Figure 3 It is a schematic configuration diagram showing another example of the image forming apparatus according to the present embodiment.

[0279] Figure 3 The image forming apparatus 120 shown is a multi-color image forming apparatus of a tandem type equipped with four process cartridges 300. In the image forming apparatus 120, four process cartridges 300 are arranged on the intermediate transfer body 50, respectively, and a single electrophotographic photoreceptor is used for each color. In addition, the image forming apparatus 120 has the same structure as the image forming apparatus 100 except for the tandem type.

[0280] Example

[0281] The following examples are given to further specifically describe the electrophotographic photosensitive body involved in this embodiment. The materials, usage amounts, ratios, processing steps, etc. shown in the following examples can be appropriately changed as long as they do not deviate from the purpose of this embodiment. Therefore, the scope of the electrophotographic photosensitive body involved in this embodiment should not be interpreted in a restrictive manner by the specific examples shown below.

[0282] (Examples 1 to 8 and Comparative Examples 1 to 6)

[0283] <Production of photoreceptor>

[0284] -Production of bottom coating layer-

[0285] Zinc oxide: (average particle size 70 nm: manufactured by TAYCA CORPORATION; specific surface area 15 m 2 / g) and 500 parts by mass of toluene were stirred and mixed, and 1.3 parts by mass of a silane coupling agent (KBM503: manufactured by Shin-Etsu Chemical Co., Ltd.) was added and stirred for 2 hours. Then, the toluene was removed by vacuum distillation, and sintering was performed at 120°C for 3 hours to obtain a silane coupling agent surface-treated zinc oxide.

[0286] 110 parts by mass of surface-treated zinc oxide and 500 parts by mass of tetrahydrofuran were stirred and mixed, and a solution of 0.6 parts by mass of alizarin dissolved in 50 parts by mass of tetrahydrofuran was added, followed by stirring at 50° C. for 5 hours. Then, the zinc oxide to which alizarin was imparted was filtered out by vacuum filtration, and then dried under reduced pressure at 60° C. to obtain zinc oxide to which alizarin was imparted.

[0287] 60 parts by mass of zinc oxide to impart alizarin, 13.5 parts by mass of a curing agent (blocked isocyanate, SUMIDUR3175, manufactured by Sumitomo Bayer Urethane Co., Ltd.), 38 parts by mass of a solution of 15 parts by mass of a butyral resin (S-LEC BM-1, manufactured by SEKISUI CHEMICAL CO., LTD.) dissolved in 85 parts by mass of methyl ethyl ketone, and 25 parts by mass of methyl ethyl ketone were mixed and used. The glass beads were dispersed by a sand mill for 2 hours to obtain a dispersion.

[0288] To the obtained dispersion were added 0.005 parts by mass of dioctyltin dilaurate and 40 parts by mass of silicone resin particles (Tospearl 145, manufactured by GE Toshiba Silicones) as a catalyst to obtain a coating liquid for forming an undercoat layer.

[0289] A cylindrical aluminum substrate with a diameter of 30 mm, a length of 340 mm, and a wall thickness of 1 mm was prepared as a conductive substrate. The obtained coating liquid for forming an undercoat layer was applied to the cylindrical aluminum substrate by dip coating, and dried and cured at 170°C for 40 minutes to obtain an undercoat layer with a thickness of 18.7 μm.

[0290] - Fabrication of Charge Generation Layer -

[0291] A mixture of 15 parts by mass of hydroxygallium phthalocyanine having diffraction peaks at Bragg angles (2θ±0.2°) of at least 7.3°, 16.0°, 24.9°, and 28.0° in an X-ray diffraction spectrum using Cukα characteristic X-rays as a charge generating material, 10 parts by mass of a vinyl chloride-vinyl acetate copolymer resin (VMCH, manufactured by Nippon Unicar Company Limited) as a binder resin, and 200 parts by mass of n-butyl acetate was used as a diameter The glass beads were dispersed by a sand mill for 4 hours. 175 parts by mass of n-butyl acetate and 180 parts by mass of methyl ethyl ketone were added to the obtained dispersion, and the mixture was stirred to obtain a coating solution for forming a charge generating layer.

[0292] The obtained coating liquid for forming a charge generating layer was dip-coated on the undercoat layer previously formed on the cylindrical aluminum substrate, and dried at room temperature (25° C.) to form a charge generating layer with a film thickness of 0.2 μm.

[0293] - Fabrication of Charge Transport Layer -

[0294] First, a polycarbonate copolymer (1) was obtained in the following manner.

[0295] In a flask equipped with a phosgene blowing tube, a thermometer and a stirrer, 106.9 g (0.398 mol) of 1,1-bis(4-hydroxyphenyl)cyclohexane (hereinafter referred to as "Z"), 24.7 g (0.133 mol) of 4,4'-dihydroxybiphenyl (hereinafter referred to as "BP"), 0.41 g of dithionite, 825 ml of 9.1% sodium hydroxide aqueous solution (2.018 mol of sodium hydroxide) and 500 ml of dichloromethane were added and dissolved under a nitrogen atmosphere, and 76.2 g (0.770 mol) of phosgene was blown in over 75 minutes while stirring and maintaining the temperature in the range of 18° C. to 21° C. to carry out a phosgenation reaction. After the phosgenation reaction was completed, 1.11 g (0.0075 mol) of p-tert-butylphenol and 54 ml (0.266 mol of sodium hydroxide) of 25% aqueous solution were added and stirred, and 0.18 mL (0.0013 mol) of triethylamine was added during the reaction, and the reaction was carried out at a temperature of 30°C to 35°C for 2.5 hours. The separated dichloromethane phase was washed with acid and water until the inorganic salts and amines disappeared, and then the dichloromethane was removed to obtain a polycarbonate copolymer (1). The ratio of the structural units of Z and BP in the polycarbonate was 75:25 in terms of molar ratio.

[0296] Next, 25 parts by mass of N,N'-diphenyl-N,N'-bis(3-methylphenyl)-[1,1']biphenyl-4,4'-diamine (TPD), 20 parts by mass of the compound represented by the structural formula (A), and 55 parts by mass of a polycarbonate copolymer (1) (viscosity average molecular weight: 50,000) as a binder resin were added and dissolved in 560 parts by mass of tetrahydrofuran and 240 parts by mass of toluene to obtain a coating liquid for a charge transport layer. The coating liquid was applied to the charge generating layer and dried at 135°C for 45 minutes to form a charge transport layer with a film thickness of 20 μm.

[0297] [Chemical formula 8]

[0298]

[0299] -Production of protective layer-

[0300] The amount of the compound described in Table 1 as a reactive charge transport material having a hydroxyl group, the amount of the compound described in Table 1 as a compound having a benzene ring without a hydroxyl group, and 4.4 parts by mass of a non-charge transport material containing a reactive group, i.e., a curable resin: benzoguanamine resin (NICALAC BL-60 manufactured by SANWA CHEMICAL CO., LTD.) were added to 220 parts by mass of the solvent described in Table 1, and after mixing and dissolving, 0.1 parts by mass of NACURE5225 (manufactured by King Industries, Inc.) was added as a curing catalyst to obtain a coating liquid for forming a surface protective layer.

[0301] The coating liquid for forming the surface protective layer was dip-coated on the charge transport layer, air-dried at room temperature (25° C.) for 30 minutes, and then heated from room temperature to the drying temperature (reaching temperature) shown in Table 1 under a nitrogen flow and an oxygen concentration of 110 ppm, and maintained for the drying time (holding time) shown in Table 1 for heat treatment and cured. Then, a surface protective layer with a film thickness of 10 μm was formed. Each electrophotographic photoreceptor was obtained in the above manner.

[0302] <Image blur suppression evaluation>

[0303] As an image forming apparatus, a FUJIFILM Business Innovation DocuCentre-V C2263 containing an electrostatic image developer was prepared, and the prepared electrophotographic photosensitive body was set, and 100,000 sheets of A4 paper were fed, and then placed under high temperature and high humidity (28°C 85% RH) for more than 12 hours. After being placed, 10 halftone images (image density 30%) were drawn, and image blur (toner white spots) was evaluated. The evaluation criteria are shown below.

[0304] A: No image blur at all

[0305] B: No image blur that is a problem in image quality

[0306] C: Image blur occurs, which is problematic in terms of image quality

[0307] <Wear suppression evaluation>

[0308] The film thickness of the prepared electrophotographic photoreceptor was measured with an eddy current film thickness meter before and after 100,000 A4 sheets were fed in the image blur suppression evaluation. The average wear rate was calculated by dividing the average film thickness difference before and after the feeding by the feeding amount.

[0309] The smaller the average wear rate (nm / kcyc, wear amount per 1,000 A4 sheets fed), the better the wear suppression property. The average wear rate is preferably less than 4.0 nm / kcyc, and more preferably less than 3.0 nm / kcyc, for example.

[0310] The details and evaluation results of each example are summarized in Table 1 below.

[0311]

[0312] The details of the abbreviations described in Table 1 are as follows.

[0313] H-1: The following compound

[0314] H-2: The following compound

[0315] H-3: The following compound

[0316] [Chemical formula 9]

[0317]

[0318] B-1: The following compound

[0319] [Chemical formula 10]

[0320]

[0321] As shown in Table 1, the electrophotographic photoreceptors of Examples were superior to the electrophotographic photoreceptors of Comparative Examples in both abrasion suppression and image blur suppression.

[0322] (1) An electronic photographic photosensitive body for contact charging based on direct current voltage, comprising: a conductive substrate; an undercoat layer disposed on the conductive substrate; a charge generating layer disposed on the undercoat layer; a charge transport layer disposed on the charge generating layer; and a surface protective layer disposed on the charge transport layer, wherein the surface protective layer is a cured film of a composition containing a reactive charge transport material and has a hydroxyl group and a benzene ring structure, and the value of the peak surface area of ​​the hydroxyl group / the peak surface area of ​​the benzene ring structure in a total reflection measurement method of infrared spectroscopy analysis is greater than 0.05 and less than 0.36.

[0323] (2) The electrophotographic photoreceptor for contact charging by direct current voltage according to (1), wherein

[0324] The surface protection layer is a cured film of a composition including a compound having a hydroxyl group and a compound having no hydroxyl group but having a benzene ring structure.

[0325] (3) The electrophotographic photoreceptor for contact charging by direct current voltage according to (2), wherein

[0326] The compound having the hydroxyl group is the reactive charge transport material.

[0327] (4) The electrophotographic photoreceptor for contact charging by direct current voltage according to (2) or (3), wherein

[0328] The compound having a hydroxyl group is a compound having a triallylamine structure.

[0329] (5) The electrophotographic photoreceptor for contact charging by direct current voltage according to any one of (2) to (4), wherein

[0330] The compound having no hydroxyl group but having a benzene ring structure is a compound having a triallylamine structure.

[0331] (6) The electrophotographic photoreceptor for contact charging by direct current voltage according to any one of (2) to (5), wherein

[0332] The value of the mass ratio MH / MB of the content MH of the compound having a hydroxyl group and the content MB of the compound having no hydroxyl group and having a benzene ring structure in the composition is 5 or more and 20 or less.

[0333] (7) The electrophotographic photoreceptor for contact charging by direct current voltage according to any one of (1) to (6), wherein

[0334] The surface protection layer does not have a carboxyl group.

[0335] (8) The electrophotographic photoreceptor for contact charging by direct current voltage according to any one of (1) to (7), wherein

[0336] The surface protection layer does not have silicon atoms.

[0337] (9) A process cartridge comprising the electrophotographic photoreceptor for contact charging by direct current voltage according to any one of (1) to (8), wherein:

[0338] The process cartridge is attached to and detached from an image forming apparatus, and performs contact charging on the electrophotographic photoreceptor by a DC voltage.

[0339] (10) An image forming device, comprising: an electrophotographic photosensitive body for contact charging based on a DC voltage as described in any one of (1) to (8); a charging device for contact charging the surface of the electrophotographic photosensitive body by a DC voltage; an electrostatic latent image forming device for forming an electrostatic latent image on the charged surface of the electrophotographic photosensitive body; a developing device for developing the electrostatic latent image formed on the surface of the electrophotographic photosensitive body by a developer containing a colorant to form a colorant image; and a transfer device for transferring the colorant image to the surface of a recording medium.

[0340] According to the invention involved in (1) or (2), there is provided an electronic photographic photosensitive body for contact charging based on direct current voltage, which has a conductive substrate, an undercoat layer, a charge generating layer, a charge transport layer and a surface protective layer, and wherein when the surface protective layer is a cured film of a composition containing a reactive charge transport material, the value of the peak surface area of ​​the hydroxyl group / the peak surface area of ​​the benzene ring structure in the total reflection measurement method of infrared spectroscopy is 0.05 or less or exceeds 0.36, and the wear suppression and image blur suppression are excellent compared with the case.

[0341] According to the invention of (3), there is provided an electrophotographic photoreceptor for contact charging by direct current voltage, which has better wear suppression and image blur suppression than when the reactive charge transport material is a compound having only a benzene ring structure and not having the hydroxyl group.

[0342] According to the invention of (4), there is provided an electrophotographic photoreceptor for contact charging by direct current voltage, which has better wear suppression and image blur suppression than when the compound having the hydroxyl group is a compound having a mono / or diallylamine structure instead of a triallylamine structure.

[0343] According to the invention involved in (5), there is provided an electronic photographic photosensitive body for contact charging based on a DC voltage, which has better wear inhibition and image blur inhibition than the case where the compound having a benzene ring structure but not having the hydroxyl group is a compound having a mono / or diallylamine structure but not having a triallylamine structure.

[0344] According to the invention involved in (6), there is provided an electronic photographic photosensitive body for contact charging based on DC voltage, which has better wear inhibition and image blur inhibition than the case where the mass ratio MH / MB of the content MH of the compound having a hydroxyl group to the content MB of the compound having a benzene ring structure without a hydroxyl group in the composition is less than 5 or greater than 20.

[0345] According to the invention as set forth in (7), there is provided an electrophotographic photoreceptor for contact charging by direct current voltage, which has better wear suppression performance and image blur suppression performance than when the surface protective layer has a carboxyl group.

[0346] According to the invention as set forth in (8), there is provided an electrophotographic photoreceptor for contact charging by direct current voltage, which has better wear suppression performance and image blur suppression performance than when the surface protective layer has silicon atoms.

[0347] According to the invention involved in (9) or (10), there is provided an electronic photographic photosensitive body which is contact-charged by a DC voltage and has a conductive substrate, an undercoat layer, a charge generating layer, a charge transport layer and a surface protective layer, wherein the surface protective layer is a cured film of a composition containing a reactive charge transport material, and the value of the peak surface area of ​​the hydroxyl group / the peak surface area of ​​the benzene ring structure in the total reflection measurement method of infrared spectroscopy is less than 0.05 or greater than 0.36, and the processing box or image forming device has excellent wear suppression and image blur suppression properties.

[0348] The above-mentioned embodiments of the present invention are provided for the purpose of illustration and description. In addition, the embodiments of the present invention do not fully and exhaustively include the present invention, and do not limit the present invention to the disclosed methods. Obviously, various modifications and changes are self-evident to those skilled in the art to which the present invention belongs. The present embodiment is selected and described in order to most easily understand the principles of the present invention and its application. Thus, other technicians in the art can understand the present invention through various variations optimized for specific uses assumed to be various embodiments. The scope of the present invention is defined by the above claims and their equivalents.

Claims

1. An electrophotographic photoreceptor for contact charging based on a DC voltage, comprising: Conductive substrate; A lower coating layer is disposed on the conductive substrate; A charge generating layer is disposed on the lower coating layer; A charge transport layer, disposed on the charge generation layer; and A surface protection layer is disposed on the charge transport layer, The surface protection layer is a cured film of a composition containing a reactive charge transport material, has a hydroxyl group and a benzene ring structure, and the value of the peak surface area of ​​the hydroxyl group / the peak surface area of ​​the benzene ring structure in total reflection measurement by infrared spectroscopy is greater than 0.05 and less than 0.

36.

2. The electrophotographic photoreceptor for contact charging by direct current voltage according to claim 1, wherein The surface protection layer is a cured film of a composition including a compound having a hydroxyl group and a compound having no hydroxyl group but having a benzene ring structure.

3. The electrophotographic photoreceptor for contact charging by direct current voltage according to claim 2, wherein: The compound having the hydroxyl group is the reactive charge transport material.

4. The electrophotographic photoreceptor for contact charging by direct current voltage according to claim 2 or 3, wherein: The compound having a hydroxyl group is a compound having a triallylamine structure.

5. The electrophotographic photoreceptor for contact charging by direct current voltage according to any one of claims 2 to 4, wherein The compound having no hydroxyl group but having a benzene ring structure is a compound having a triallylamine structure.

6. The electrophotographic photoreceptor for contact charging by direct current voltage according to any one of claims 2 to 5, wherein The value of the mass ratio MH / MB of the content MH of the compound having a hydroxyl group and the content MB of the compound having no hydroxyl group and having a benzene ring structure in the composition is 5 or more and 20 or less.

7. The electrophotographic photoreceptor for contact charging by direct current voltage according to any one of claims 1 to 6, wherein The surface protection layer does not have a carboxyl group.

8. The electrophotographic photoreceptor for contact charging by direct current voltage according to any one of claims 1 to 7, wherein The surface protection layer does not have silicon atoms.

9. A process cartridge comprising the electrophotographic photoreceptor for contact charging by direct current voltage according to any one of claims 1 to 8, wherein: The process cartridge is attached to and detached from an image forming apparatus, and performs contact charging on the electrophotographic photoreceptor by a DC voltage.

10. An image forming apparatus comprising: The electrophotographic photoreceptor for contact charging by direct current voltage according to any one of claims 1 to 8; A charging device for contact charging the surface of the electrophotographic photoreceptor by means of a DC voltage; An electrostatic latent image forming device for forming an electrostatic latent image on the charged surface of the electrophotographic photoreceptor; a developing device for developing the electrostatic latent image formed on the surface of the electrophotographic photoreceptor with a developer containing a toner to form a toner image; and The transfer device transfers the toner image to the surface of a recording medium.

Images