JP2023042057A - Electrophotographic photoreceptor and manufacturing method thereof, process cartridge, and electrophotographic device - Google Patents

Abstract

To provide an electrophotographic photoreceptor which can have excellent abrasion resistance and which hardly generates image stripes even when images are continuously output.SOLUTION: An electrophotographic photoreceptor includes a support and a photosensitive layer on the support. A surface layer of the electrophotographic photoreceptor is a polymer film of a composition which contains fluorine resin particles, a charge transport compound having two or more of hydroxyalkyl groups, and polyvinyl acetal.SELECTED DRAWING: None

Description

The present disclosure relates to an electrophotographic photoreceptor, a method for manufacturing an electrophotographic photoreceptor, a process cartridge, and an electrophotographic apparatus.

In recent years, a charge-transporting compound having a polymerizable functional group has been added to the outermost layer (hereinafter referred to as "surface layer") of an electrophotographic photoreceptor in order to achieve a high level of both durability and electrical properties. It is known to use polymeric membranes that have been polymerized. Further, even in high-speed printing, the surface layer of the electrophotographic photoreceptor is required to have excellent lubricity in order to suppress an increase in the frictional force between the cleaning blade and the electrophotographic photoreceptor.

Patent Document 1 discloses an electrophotographic photoreceptor whose surface layer is a polymer film obtained by polymerizing a composition containing fluororesin particles as lubricating particles and a charge-transporting compound having three hydroxyalkyl groups. It is

Further, Patent Document 2 discloses that the dispersibility of fluororesin particles is enhanced by incorporating a polymer having a specific structural unit into the surface layer of an electrophotographic photoreceptor.

JP-A-2002-6528 JP 2018-77450 A

One aspect of the present disclosure is directed to providing an electrophotographic photoreceptor that can have excellent wear resistance and is less likely to cause image streaks even when continuous image output is performed.

Another aspect of the present disclosure is directed to providing a method for manufacturing an electrophotographic photoreceptor according to the present disclosure.

Another aspect of the present disclosure is directed to providing a process cartridge having the electrophotographic photoreceptor according to the present disclosure.

Another aspect of the present disclosure is directed to providing an electrophotographic apparatus having the electrophotographic photoreceptor according to the present disclosure.

According to one aspect of the present disclosure, an electrophotographic photoreceptor having a support and a photosensitive layer on the support,
An electrophotographic photoreceptor, wherein the surface layer of the electrophotographic photoreceptor is a polymer film of a composition containing fluororesin particles, a charge-transporting compound having two or more hydroxyalkyl groups, and polyvinyl acetal. is provided.

Further, according to another aspect of the present disclosure, a method for manufacturing an electrophotographic photoreceptor, comprising:
preparing a surface layer coating liquid containing a composition containing fluororesin particles, a charge-transporting compound having two or more hydroxyalkyl groups, and polyvinyl acetal;
a step of forming a coating film of the surface layer coating liquid; and a step of forming a surface layer of an electrophotographic photoreceptor by polymerizing the coating film;
A method for producing an electrophotographic photoreceptor is provided.

According to another aspect of the present disclosure, there is provided a process cartridge detachably attachable to an electrophotographic apparatus main body,
The process cartridge integrally supports the electrophotographic photosensitive member according to the present disclosure and at least one means selected from the group consisting of charging means, exposure means, developing means, transfer means and cleaning means. A process cartridge is provided.

Further, according to another aspect of the present disclosure, there is provided an electrophotographic apparatus including the electrophotographic photoreceptor according to the present disclosure, charging means, exposure means, developing means, and transfer means.

According to one aspect of the present disclosure, it is possible to provide an electrophotographic photoreceptor that can have excellent wear resistance and is less likely to cause image streaks even when continuous image output is performed.

Further, according to another aspect of the present disclosure, a method for manufacturing an electrophotographic photoreceptor according to the present disclosure can be provided.

Further, according to another aspect of the present disclosure, a process cartridge having the electrophotographic photoreceptor according to the present disclosure can be provided.

Further, according to another aspect of the present disclosure, it is possible to provide an electrophotographic apparatus having the electrophotographic photoreceptor according to the present disclosure.

1 is a diagram showing an example of the layer structure of an electrophotographic photoreceptor of the present disclosure; FIG. 1 is a diagram showing an example of a schematic configuration of an electrophotographic apparatus including a process cartridge having an electrophotographic photoreceptor of the present disclosure; FIG.

<Circumstances leading to the invention>
The present inventors have studied the electrophotographic photoreceptor described in Patent Document 1, and as a result, image streaks are likely to occur when continuous image output is performed using the electrophotographic photoreceptor described in Patent Document 1. I discovered that it might be.

This is because the fluororesin particles present in the surface layer are not sufficiently dispersed, so that when the surface of the electrophotographic photosensitive member is scraped off during continuous image output, the fluororesin particles form the surface layer. This is probably because the lubricity may not be sufficient. When the lubricity of the surface of the electrophotographic photoreceptor is reduced, the posture of the cleaning blade tends to become unstable, and the cleaning blade may not remove residual toner from the surface of the photoreceptor. As a result, the present inventors speculate that the toner remaining on the electrophotographic photosensitive member is developed on paper when the next image is output, resulting in image streaks.

The present inventors used the polymer having a perfluoroalkyl group described in Patent Document 2 in order to increase the dispersibility of the fluororesin particles in the surface layer. It was difficult to obtain sufficient dispersibility in the composition containing the compound. The reason why dispersibility is difficult to increase even when the above polymer is used is that while the above polymer can be adsorbed to the fluororesin particles to increase the dispersibility, the above polymer and fluororesin particles have two hydroxyalkyl groups. This is thought to be due to the low affinity for charge-transporting compounds having at least one charge-transporting compound. As a result, in a composition containing a charge-transporting compound having two or more hydroxyalkyl groups, the polymer and the fluororesin particles tend to aggregate together, and the charge-transporting compounds tend to aggregate together. It is thought that it will become easier.

From the viewpoint of outputting high-quality images, it is naturally required that image streaks are less likely to occur even when images are output continuously.

Based on the above considerations, the present inventors have investigated an electrophotographic photoreceptor that can have excellent wear resistance and that does not easily cause image streaks even when continuous image output is performed. As a result, the inventors have found that an electrophotographic photoreceptor having the above properties can be obtained by including polyvinyl acetal in the composition of the polymer film that is the surface layer of the electrophotographic photoreceptor.

The inventors of the present invention discovered that the inclusion of polyvinyl acetal facilitates dispersion of fluororesin particles to a size close to the primary particle size even in a composition containing a charge-transporting compound having two or more hydroxyalkyl groups. bottom. This is because the polyvinyl acetal not only adsorbs to the fluororesin particles and functions as a dispersant, but also is compatible with the charge-transporting compound having two or more hydroxyalkyl groups, causing aggregation of the fluororesin particles in the composition. It is thought that this is because it becomes difficult to use. As a result, the present inventors presume that even when images are output continuously, the lubricity of the surface layer due to the fluororesin particles is maintained well, and image streaks are less likely to occur.

<Structure of Electrophotographic Photoreceptor>
The structure of the electrophotographic photoreceptor will be described with reference to FIG. FIG. 1 schematically shows an example of the layer structure of an electrophotographic photoreceptor according to this embodiment.

As shown in FIGS. 1A and 1B, the electrophotographic photoreceptor 106 comprises a support 101 and a photosensitive layer 105 provided thereon. In the case of FIG. 1(a), the photosensitive layer 105 is composed of the charge generation layer 102 and the charge transport layer 104, and the charge transport layer 104 is the surface layer. In the case of FIG. 1(b), the photosensitive layer 105 is composed of the charge generation layer 102, the first charge transport layer 103, and the second charge transport layer 104, and the surface layer is the second charge transport layer 104. is. As shown in FIGS. 1(a) and 1(b), the charge transport layer according to the present disclosure may be one layer or multiple layers. Further, in the present disclosure, an undercoat layer or an intermediate layer, which will be described later, may be provided between the support 101 and the photosensitive layer 105 .

<Surface layer>
The surface layer according to the present disclosure is a polymer film of a composition containing fluororesin particles, a charge-transporting compound having two or more hydroxyalkyl groups, and polyvinyl acetal.

<Fluororesin particles>
Examples of the fluororesin particles according to the present disclosure include tetrafluoroethylene resin particles, trifluoroethylene resin particles, tetrafluoroethylene hexafluoropropylene resin particles, vinyl fluoride resin particles, vinylidene fluoride resin particles, Examples include fluorodichloride ethylene resin particles. Particles of copolymers of these resins are also included. Among these, tetrafluoroethylene resin particles are preferred.

The average particle diameter of the primary particles of the fluororesin particles is preferably 0.40 μm or less, more preferably 0.30 μm or less, and more preferably 0.20 μm or less, in terms of good lubricity. preferable. The lower limit is not particularly limited, and is preferably 0.05 μm or more, more preferably 0.10 μm or more, and even more preferably 0.15 μm or more.

The number average particle diameter of the primary particles of the fluororesin particles is measured using a scanning electron microscope (S-4800, manufactured by Hitachi Ltd.). In a field of view magnified up to 50,000 times, the major diameter of primary particles of 100 fluororesin particles is randomly measured to determine the number average particle diameter. The observation magnification is appropriately adjusted according to the size of the fluororesin particles.

The content of the fluororesin particles is preferably 1.0% by mass or more and 40.0% by mass or less with respect to the total mass of the composition forming the surface layer. When it is 1.0% by mass or more, a surface layer having sufficient lubricity can be easily obtained. More preferably, it is 5.0% by mass or more. Moreover, when it is 40.0% by mass or less, it is easy to obtain a surface layer having sufficient abrasion resistance. It is more preferably 30.0% by mass or less, still more preferably 15.0% by mass or less.

Examples of dispersion methods for dispersing fluororesin particles include media dispersers such as ball mills, vibrating ball mills, attritors, sand mills, and horizontal sand mills, and medialess dispersers such as stirring, ultrasonic dispersers, roll mills, and high-pressure homogenizers. used. Examples of high-pressure homogenizers include a collision system in which a dispersion liquid is dispersed by liquid-liquid collision or liquid-wall collision in a high pressure state, and a penetration system in which a fine flow path is penetrated and dispersed in a high pressure state.

<Charge-Transporting Compound Having Two or More Hydroxyalkyl Groups>
The charge-transporting compound according to the present disclosure has two or more hydroxyalkyl groups. When the charge-transporting compound has two or more hydroxyalkyl groups, the surface layer of the electrophotographic photoreceptor becomes a polymer film containing the polycondensate of the charge-transporting compound, and the electrophotographic photosensitive member has excellent wear resistance. Body is easy to obtain. More preferably, the charge-transporting compound has 3 or more hydroxyalkyl groups, and more preferably 4 or more hydroxyalkyl groups.

Examples of the charge-transporting compound having two or more hydroxyalkyl groups include at least one compound selected from the group consisting of compounds represented by the following formula (1) and compounds represented by the following formula (2). .

(In Formula (1), Ar ¹¹ to Ar ¹³ each independently represent a substituted or unsubstituted aryl group. At least two of Ar ¹¹ to Ar ¹³ are aryl groups having a hydroxyalkyl group as a substituent. The substituents Ar ¹¹ to Ar ¹³ may have include alkyl groups such as methyl group, ethyl group and propyl group, alkoxy groups such as methoxy group, ethoxy group and propoxy group, fluorine atom and bromine atom. , chlorine atom, iodine atom, etc. The aryl group represented by Ar ¹¹ to Ar ¹³ includes one hydrogen atom selected from benzene, naphthalene, fluorene, phenanthrene, anthracene, pyrene, biphenyl, terphenyl and stilbene. and monovalent groups excluding.)

(In Formula (2), Ar ²¹ to Ar ^{24 each} independently represent a substituted or unsubstituted aryl group, and Ar ²⁵ represents a substituted or unsubstituted arylene group ^. The second is an aryl group having a hydroxyalkyl group as a substituent, and the substituents that Ar ²¹ to Ar ²⁴ and Ar ²⁵ may have include an alkyl group such as a methyl group, an ethyl group and a propyl group, a methoxy alkoxy groups such as ethoxy group and propoxy group, and halogen atoms such as fluorine atom, bromine atom, chlorine atom, iodine atom, etc. Aryl groups represented by Ar ²¹ to Ar ²⁴ include benzene, naphthalene, fluorene, and phenanthrene. , anthracene, pyrene, biphenyl, terphenyl, stilbene with one hydrogen atom removed, and arylene groups represented by Ar ²⁵ include benzene, naphthalene, fluorene, phenanthrene, anthracene, pyrene, biphenyl , terphenyl, and stilbene from which two hydrogen atoms have been removed.)
When Ar ¹¹ to Ar ¹³ , Ar ²¹ to Ar ²⁴ and Ar ²⁵ have an alkyl group or an alkoxy group, the number of carbon atoms in the alkyl group or alkoxy group is preferably 1 to 6, and preferably 1 to 3. is more preferred.

A hydroxyalkyl group possessed by the charge-transporting compound includes a hydroxymethyl group, a hydroxyethyl group, a hydroxypropyl group, a hydroxybutyl group, and the like. From the viewpoint of abrasion resistance, a hydroxymethyl group or a hydroxyethyl group is preferred, and a hydroxymethyl group is more preferred.

Examples of charge-transporting compounds having two or more hydroxyalkyl groups according to the present disclosure are shown below, but the present disclosure is not limited thereto.

Among the above, at least one charge-transporting property selected from the group consisting of a compound represented by formula (A-7), a compound represented by formula (B-3), and a compound represented by formula (B-4) Compounds are more preferred.

These charge-transporting compounds having two or more hydroxyalkyl groups may be used singly or in combination of two or more.

The charge-transporting compound having two or more hydroxyalkyl groups preferably accounts for 50.0% by mass or more, more preferably 75.0% by mass or more, of the total mass of the composition constituting the surface layer. preferable. Moreover, it is preferable that it is 90.0 mass % or less as an upper limit.

<Polyvinyl acetal>
Polyvinyl acetal is a polymer obtained by reacting polyvinyl alcohol with aldehyde. Due to the acetal moiety or hydroxyl group in the polymer, the polyvinyl acetal tends to increase the affinity with the charge-transporting compound according to the present disclosure, and it is believed that aggregation of the fluororesin particles and aggregation of the charge-transporting compound are unlikely to occur. be done. More preferably, the polyvinyl acetal according to the present disclosure is a polyvinyl butyral resin obtained by reacting polyvinyl alcohol and butyraldehyde.

In addition, since it is believed that the affinity with the charge-transporting compound according to the present disclosure increases, the polyvinyl acetal preferably has a hydroxyl group, and may contain a monomer unit represented by the following formula (V). preferable. In addition, the number of moles of the unit represented by the following formula (V) (hereinafter also referred to as the amount of hydroxyl groups) is 25 mol% or more and 40 mol% or less with respect to the total number of moles of the monomer units constituting the polyvinyl acetal. is more preferable. Identification of the monomer units contained in the polymer and measurement of the content ratio of each monomer unit in the polymer can be performed by NMR measurement, mass spectrometry, or the like.

Examples of polyvinyl acetal include S-lec B series, K (KS) series, SV series (manufactured by Sekisui Chemical Co., Ltd.), Mobital series (manufactured by Kuraray Co., Ltd.), and the like. More specifically, S-LEC BM-1 (amount of hydroxyl group: 34 mol%, degree of butyralization 65±3 mol%, molecular weight: 40000), BH-3 (amount of hydroxyl group: 34 mol%, degree of butyralization 65±3 mol %, molecular weight: 110000), BH-6 (hydroxyl group content: 30 mol%, butyralization degree 69 ± 3 mol%, molecular weight: 920000), BX-1 (hydroxyl group content: 33 ± 3 mol%, degree of acetalization 66 mol %, molecular weight: 100000), BX-5 (hydroxyl group content: 33 ± 3 mol%, acetalization degree 66 mol%, molecular weight: 130000), BM-2 (hydroxyl group content: 31 mol%, butyralization degree 68 ± 3 mol %, molecular weight: 520000), BM-5 (hydroxyl group content: 34 mol%, butyralization degree 65 ± 3 mol%, molecular weight: 530000), BL-1 (hydroxyl group content: 36 mol%, butyralization degree 63 ± 3 mol %, molecular weight: 190000), BL-1H (hydroxyl group content: 30 mol%, butyralization degree 69 ± 3 mol%, molecular weight: 20000), BL-2 (hydroxyl group content: 36 mol%, butyralization degree 63 ± 3 mol %, molecular weight: 270000), BL-2H (hydroxyl group content: 29 mol%, butyralization degree 70 ± 3 mol%, molecular weight: 280000), BL-10 (hydroxyl group content: 28 mol%, butyralization degree 71 ± 3 mol %, molecular weight: 150000), BL-S (hydroxyl group 22 mol%, butyralization degree 74 ± 3 mol%, molecular weight: 23000), KS-10 (hydroxyl group content: 25 mol%, acetalization degree 65 ± 3 mol%, molecular weight: 170000), Mobital B145 (hydroxyl group content: 21 to 27 mol%, acetalization degree 67 to 75 mol%), B16H (hydroxyl group content: 26 to 31 mol%, acetalization degree 66 to 74 mol%, molecular weight: 1 to 20000).

Polyvinyl acetals used in the present disclosure may be used alone or in combination of two or more.

The content of polyvinyl acetal in the composition is preferably 1.0% by mass or more and 100.0% by mass or less with respect to the content of the fluororesin particles. More preferably, it is 50.0% by mass or less, and still more preferably 30.0% by mass or less. Moreover, it is more preferably 10.0% by mass or more, more preferably 17.0% by mass or more, and even more preferably 20.0% by mass or more. That is, one aspect of a preferable numerical range is 20.0% by mass or more and 50.0% by mass or less.

Moreover, the content of the polyvinyl acetal in the composition is preferably 0.10% by mass or more and 35.00% by mass or less with respect to the content of the charge-transporting compound. It is more preferably 0.20% by mass or more, and still more preferably 2.00% by mass or more. Further, it is more preferably 30.00% by mass or less, more preferably 15.00% by mass or less, more preferably 10.00% by mass or less, and 5.00% by mass or less. is more preferable, and 3.00% by mass or less is even more preferable.

In addition, it is preferable that the composition according to the present disclosure further contains at least one compound selected from the group consisting of phenol compounds, melamine compounds, and benzoguanamine compounds in terms of improving the wear resistance of the surface layer. . Although the reason why the wear resistance is improved is not clear, the present inventors presume that the inclusion of the compound facilitates the formation of hydrogen bonds in the composition constituting the surface layer. there is

Also, the composition according to the present disclosure may further contain an acid catalyst as a curing catalyst to facilitate curing. Acid catalysts include aliphatic carboxylic acids such as acetic acid, chloroacetic acid, trichloroacetic acid, trifluoroacetic acid, oxalic acid, maleic acid, malonic acid, and lactic acid; carboxylic acids; aliphatic and aromatic sulfonic acids such as methanesulfonic acid, dodecylsulfonic acid, benzenesulfonic acid, dodecylbenzenesulfonic acid, naphthalenesulfonic acid, toluenesulfonic acid; and thermal latent catalysts. As the thermal latent catalyst, King Industries "NACURE2501" (toluenesulfonic acid dissociation, methanol/isopropanol solvent, pH 6.0 or more and pH 7.2 or less, dissociation temperature 80 ° C.), "NACURE2107" (p-toluenesulfonic acid Dissociation, isopropanol solvent, pH 8.0 or higher and pH 9.0 or lower, dissociation temperature 90 ° C.), "NACURE 2500" (p-toluenesulfonic acid dissociation, isopropanol solvent, pH 6.0 or higher and pH 7.0 or lower, dissociation temperature 65 ° C.), " NACURE 2530" (p-toluenesulfonic acid dissociation, methanol/isopropanol solvent, pH 5.7 or more and pH 6.5 or less, dissociation temperature 65 ° C.), "NACURE 2547" (p-toluenesulfonic acid dissociation, aqueous solution, pH 8.0 or more pH 9.0 hereinafter, dissociation temperature 107 ° C.), "NACURE 2558" (p-toluenesulfonic acid dissociation, ethylene glycol solvent, pH 3.5 or higher and pH 4.5 or lower, dissociation temperature 80 ° C.), "NACUREXP-357" (p-toluenesulfonic acid dissociation , methanol solvent, pH 2.0 to pH 4.0, dissociation temperature 65 ° C.), "NACUREXP-386" (p-toluenesulfonic acid dissociation, aqueous solution, pH 6.1 to pH 6.4, dissociation temperature 80 ° C.), " NACUREXC-2211" (p-toluenesulfonic acid dissociation, pH 7.2 to pH 8.5, dissociation temperature 80 ° C.), "NACURE 5225" (dodecylbenzenesulfonic acid dissociation, isopropanol solvent, pH 6.0 to pH 7.0, dissociation temperature 120 ° C.), "NACURE 5414" (dodecylbenzene sulfonic acid dissociation, xylene solvent, dissociation temperature 120 ° C.), "NACURE 5528" (dodecylbenzene sulfonic acid dissociation, isopropanol solvent, pH 7.0 or higher and pH 8.0 or lower, dissociation temperature 120 ° C. ), "NACURE 5925" (dodecylbenzenesulfonic acid dissociation, pH 7.0 or higher and pH 7.5 or lower, dissociation temperature 130 ° C.), "NACURE 1323" (dinonylnaphthalene sulfonic acid dissociation, xylene solvent, pH 6.8 or higher and pH 7.5 or lower, dissociation temperature 150° C.), “NACURE 1419” (dinonylnaphthalenesulfonic acid dissociation, xylene/methyl isobutyl ketone solvent, dissociation temperature 150° C.), “NACURE 1557” (dinonylnaphthalenesulfonic acid dissociation, butanol/2-butoxyethanol solvent, pH 6 .5 or more and pH 7.5 or less, dissociation temperature of 150° C.), "NACUREX49-110" (dinonylnaphthalenedisulfonic acid dissociation, isobutanol/isopropanol solvent, pH 6.5 or more and pH 7.5 or less, dissociation temperature 90 ° C.), "NACURE3525" (dinonylnaphthalenedisulfonic acid dissociation, isobutanol/isopropanol solvent , pH 7.0 to pH 8.5, dissociation temperature 120 ° C.), “NACUREXP-383” (dinonylnaphthalenedisulfonic acid dissociation, xylene solvent, dissociation temperature 120 ° C.), “NACURE 3327” (dinonylnaphthalenedisulfonic acid dissociation, iso Butanol / isopropanol solvent, pH 6.5 or higher and pH 7.5 or lower, dissociation temperature 150 ° C.), "NACURE 4167" (phosphoric acid dissociation, isopropanol / isobutanol solvent, pH 6.8 or higher and pH 7.3 or lower, dissociation temperature 80 ° C.), " NACUREXP-297" (phosphoric acid dissociation, water/isopropanol solvent, pH 6.5 or higher and pH 7.5 or lower, dissociation temperature 90 ° C., "NACURE 4575" (phosphoric acid dissociation, pH 7.0 or higher and pH 8.0 or lower, dissociation temperature 110 ° C.) etc.

Moreover, the content of the acid catalyst with respect to the total mass of the composition is preferably 0.1% by mass or more and 20.0% by mass or less, in order that the effect of accelerating curing becomes remarkable. It is more preferably 10.0% by mass or less, more preferably 5.0% by mass or less, and even more preferably 1.0% by mass or less.

<Additive>
The surface layer of the present disclosure may further contain additives such as antioxidants, UV absorbers, plasticizers, leveling agents, lubricity imparting agents, wear resistance improvers and the like. Specific examples include hindered phenol compounds, hindered amine compounds, sulfur compounds, phosphorus compounds, benzophenone compounds, siloxane-modified resins, and silicone oils.

<Method for producing electrophotographic photoreceptor>
A method for producing an electrophotographic photoreceptor according to the present disclosure includes a step of preparing a surface layer coating liquid containing a composition containing fluororesin particles, a charge-transporting compound having two or more hydroxyalkyl groups, and polyvinyl acetal;
a step of forming a coating film of the surface layer coating liquid; and a step of forming a surface layer of an electrophotographic photoreceptor by polymerizing the coating film;
characterized by having

<Method of Forming Surface Layer>
The surface layer is formed by preparing a surface layer coating solution containing each of the above materials and solvents, forming this coating film, and then applying heat, ultraviolet rays, electron beams, etc. to the coating film to promote the polymerization reaction. obtained by letting

Solvents used in the coating liquid include alcohol solvents, ketone solvents, ether solvents, sulfoxide solvents, ester solvents, and aromatic hydrocarbon solvents. As a method for applying the surface layer coating liquid, for example, a conventional method such as dip coating, push-up coating, wire bar coating, spray coating, blade coating, knife coating, or curtain coating can be used.

In addition, by carrying out the polymerization reaction under oxygen-removed conditions, a side reaction due to an oxidation reaction can be suppressed, and an effect of suppressing image deletion and improving wear resistance of the photoreceptor can be obtained. Preferably, the polymerization is carried out in a nitrogen atmosphere with an oxygen concentration of 10 ppm or more and 10000 ppm or less.

Also, the film thickness of the surface layer is preferably 1 μm or more and 50 μm or less, more preferably 5 μm or more and 25 μm or less, in terms of electrical properties.

Each element of the electrophotographic photoreceptor will be described below.

<Support>
The support used in the electrophotographic photoreceptor of the present disclosure is preferably conductive (conductive support), for example, a support made of a metal (alloy) such as aluminum, an aluminum alloy, or stainless steel. . In the case of a support made of aluminum or an aluminum alloy, an ED tube, an EI tube, or a tube obtained by cutting, electrolytic composite polishing, or wet or dry honing can also be used as the support. In addition, a metal support or a resin support on which a thin film of a conductive material such as aluminum, an aluminum alloy, or an indium oxide-tin oxide alloy is formed can also be used as the support.

Further, the surface of the support may be subjected to cutting treatment, roughening treatment, alumite treatment, or the like. Further, a support obtained by impregnating a resin with conductive particles such as carbon black, tin oxide particles, titanium oxide particles, or silver particles, or a support made of a conductive resin can also be used.

<Undercoat layer>
The undercoat layer contains, for example, conductive particles, a binder resin, and, if necessary, other additives.

The conductive particles contained in the undercoat layer preferably have conductivity with a volume resistivity of less than 10 ⁷ Ω·cm, for example. Examples of conductive particles include the following.

Metal particles (particles of aluminum, copper, nickel, silver, etc.), conductive metal oxide particles (particles of antimony oxide, indium oxide, tin oxide, zinc oxide, etc.), conductive substance particles (carbon fiber, carbon black, graphite powder particles) and the like. Among these, conductive metal oxide particles are preferred. Two or more types of conductive particles may be mixed and used. Also, the conductive particles may be subjected to surface treatment with a hydrophobizing agent (for example, a coupling agent) or the like to adjust the resistance.

The content of the conductive particles is, for example, desirably 10% by mass or more and 80% by mass or less, more preferably 40% by mass or more and 80% by mass or less, relative to the binder resin.

Examples of the binder resin contained in the undercoat layer include acetal resins such as polyvinyl butyral, polyvinyl alcohol, casein, polyamide, cellulose resin, gelatin, polyurethane, polyester, methacrylic resin, acrylic resin, polyvinyl chloride, polyvinyl acetate, Known vinyl chloride-vinyl acetate-maleic anhydride resins, silicone resins, silicone-alkyd resins, urea resins, phenol resins, phenol-formaldehyde resins, melamine resins, unsaturated urethane resins, unsaturated polyesters, alkyd resins, epoxy resins, etc. polymer resin compounds, charge-transporting resins having a charge-transporting group, and conductive resins such as polyaniline.

Among these, as the binder resin, a resin insoluble in the coating solvent of the upper layer (charge generation layer 102) is preferable. Thermosetting resins such as urea resins, phenol resins, phenol-formaldehyde resins, melamine resins, unsaturated urethane resins, unsaturated polyesters, alkyd resins and epoxy resins are particularly preferred. Also preferred is a resin obtained by reacting at least one resin selected from the group consisting of polyamide, polyester, polyether, acrylic resin, polyvinyl alcohol and polyvinyl acetal with a curing agent. When two or more of these binder resins are used in combination, the mixing ratio is set according to need.

The undercoat layer may contain metal compounds such as silicone compounds, organic zirconium compounds, organic titanium compounds, and organic aluminum compounds. The mixing ratio of the metal compound and the binder resin is not particularly limited, and is set within a range where desired electrophotographic photoreceptor characteristics can be obtained.

Resin particles may be added to the undercoat layer to adjust the surface roughness. Examples of resin particles include silicone resin particles and crosslinked polymethyl methacrylate (PMMA) resin particles. In order to adjust the surface roughness, the surface may be polished after forming the undercoat layer. As a polishing method, buffing, sandblasting, wet honing, grinding, and the like are used.

Formation of the undercoat layer is not particularly limited, and a well-known formation method is used. It is done by heating according to.

Examples of the method for applying the undercoat layer coating solution onto the conductive substrate include dip coating, thrust coating, wire bar coating, spray coating, blade coating, knife coating, and curtain coating. be done.

When dispersing the particles in the coating solution for the undercoat layer, media such as ball mills, vibrating ball mills, attritors, sand mills, and horizontal sand mills, and media such as stirring, ultrasonic dispersers, roll mills, and high-pressure homogenizers can be used. A less disperser is utilized. Here, the high-pressure homogenizer includes, for example, a collision method in which the dispersion liquid is dispersed by liquid-liquid collision or liquid-wall collision in a high-pressure state, a penetration method in which a fine flow path is penetrated and dispersed in a high-pressure state, and the like. mentioned.

The film thickness of the undercoat layer is set, for example, preferably in the range of 1 μm to 50 μm, more preferably 15 μm to 35 μm.

<Middle layer>
An intermediate layer may be further provided between the undercoat layer and the photosensitive layer 105 .

Binder resins used in the intermediate layer include acetal resins such as polyvinyl butyral, polyvinyl alcohol, casein, polyamide, cellulose resins, gelatin, polyurethane, polyester, methacrylic resins, acrylic resins, polyvinyl chloride, polyvinyl acetate, vinyl chloride- In addition to polymer resin compounds such as vinyl acetate-maleic anhydride resin, silicone resin, silicone-alkyd resin, phenol-formaldehyde resin, melamine resin, etc., organometallic compounds containing zirconium, titanium, aluminum, manganese, silicon atoms, etc. etc. These compounds may be used singly or as mixtures or polycondensates of a plurality of compounds. Among them, an organometallic compound containing zirconium or silicon is preferable because it has a low residual potential and little change in potential due to environment and little change in potential due to repeated use.

The intermediate layer may contain conductive particles. The conductive particles contained in the intermediate layer preferably have conductivity such as a volume resistivity of less than 10 ⁷ Ω·cm.

Examples of conductive particles include the following.

Metal particles (particles of aluminum, copper, nickel, silver, etc.), conductive metal oxide particles (particles of antimony oxide, indium oxide, tin oxide, zinc oxide, etc.), conductive substance particles (carbon fiber, carbon black, graphite powder particles) and the like.

Among these, conductive metal oxide particles are preferred. Two or more types of conductive particles may be mixed and used. Also, the conductive particles may be subjected to surface treatment with a hydrophobizing agent (for example, a coupling agent) or the like to adjust the resistance.

The content of the conductive particles is, for example, desirably 10% by mass or more and 80% by mass or less, more preferably 40% by mass or more and 80% by mass or less, relative to the binder resin.

The formation of the intermediate layer is not particularly limited, and a well-known forming method is used. It is done by heating with

As a method for applying the coating solution for the intermediate layer onto the undercoat layer, conventional methods such as dip coating, push-up coating, wire bar coating, spray coating, blade coating, knife coating, and curtain coating can be used. method is used.

In addition to improving the coatability of the upper layer, the intermediate layer also serves as an electrical blocking layer. may occur. Therefore, when forming the intermediate layer, it is preferable to set the thickness in the range of 0.1 μm or more and 3 μm or less. Also, the intermediate layer in this case may be used as an undercoat layer.

<Charge generation layer>
The charge generation layer in the electrophotographic photoreceptor of the present disclosure contains, for example, a charge generation compound and a binder resin. The charge generation layer may be composed of, for example, a deposited film of a charge generation compound.

Charge-generating compounds include phthalocyanine pigments such as metal-free phthalocyanine, chlorogallium phthalocyanine, hydroxygallium phthalocyanine, dichlorotin phthalocyanine, titanyl phthalocyanine, and the like. In particular, chlorogallium phthalocyanine crystals, CuKα, having strong diffraction peaks at Bragg angles (2θ±0.2°) of at least 7.4°, 16.6°, 25.5° and 28.3° for CuKα characteristic X-rays Strong diffraction peaks at at least 7.7°, 9.3°, 16.9°, 17.5°, 22.4° and 28.8° of Bragg angles (2θ ± 0.2°) for characteristic X-rays a metal-free phthalocyanine crystal having a CuKα characteristic X-ray Bragg angle (2θ±0.2°) of at least 7.5°, 9.9°, 12.5°, 16.3°, 18.6°, 25. Hydroxygallium phthalocyanine crystals with strong diffraction peaks at 1° and 28.3°, at Bragg angles (2θ ± 0.2°) of at least 9.6°, 24.1° and 27.2° for CuKα characteristic X-rays Titanyl phthalocyanine crystals with strong diffraction peaks are mentioned. Other examples of charge-generating compounds include quinone pigments, perylene pigments, indigo pigments, bisbenzimidazole pigments, anthrone pigments, and quinacridone pigments. These charge generation compounds may be used alone or in combination of two or more.

Examples of the binder resin constituting the charge generation layer include polycarbonate (eg, bisphenol A or bisphenol Z type polycarbonate), acrylic resin, methacrylic resin, polyarylate, polyester, polyvinyl chloride, polystyrene, and acrylonitrile-styrene. Copolymer resin, acrylonitrile-butadiene copolymer, polyvinyl acetal, polyvinyl acetate, polyvinyl formal, polysulfone, styrene-butadiene copolymer resin, vinylidene chloride-acrylonitrile copolymer resin, vinyl chloride-vinyl acetate-maleic anhydride resin, silicone resin, phenol-formaldehyde resin, polyacrylamide, polyamide, poly-N-vinylcarbazole and the like. These binder resins may be used alone or in combination of two or more.

The compounding ratio of the charge generation compound and the binder resin is desirably in the range of 10:1 to 1:10, for example. The charge generation layer may also contain other additives.

Formation of the charge generation layer is not particularly limited, and a well-known formation method is used. It is done by heating according to. The charge generation layer may be formed by vapor deposition of a charge generation compound.

Examples of methods for applying the charge generating layer coating solution include dip coating, thrust coating, wire bar coating, spray coating, blade coating, knife coating and curtain coating.

As a method for dispersing the charge-generating compound in the charge-generating layer coating liquid, for example, a media dispersing machine such as a ball mill, a vibrating ball mill, an attritor, a sand mill, and a horizontal sand mill can be used. Medialess dispersers such as stirring, ultrasonic dispersers, roll mills, and high-pressure homogenizers can also be used. Examples of high-pressure homogenizers include a collision system in which a dispersion liquid is dispersed by liquid-liquid collision or liquid-wall collision in a high pressure state, and a penetration system in which a fine flow path is penetrated and dispersed in a high pressure state.

The film thickness of the charge generation layer is preferably set in the range of 0.05 μm to 5.00 μm, more preferably 0.10 μm to 1.00 μm.

<Charge transport layer>
As for the charge transport layer in the electrophotographic photoreceptor of the present disclosure, only one layer may be used, or a plurality of charge transport layers may be laminated and used.

The charge transport layer contains, for example, a charge transport compound and a binder resin.

Examples of the charge-transporting compound contained in the charge-transporting layer include oxadiazole derivatives such as 2,5-bis(p-diethylaminophenyl)-1,3,4-oxadiazole, 1,3,5-tri pyrazoline derivatives such as phenyl-pyrazoline, 1-[pyridyl-(2)]-3-(p-diethylaminostyryl)-5-(p-diethylaminostyryl)pyrazoline, triphenylamine, tris[4-(4,4- diphenyl-1,3-butadienyl)phenyl]amine, N,N′-bis(3,4-dimethylphenyl)biphenyl-4-amine, tri(p-methylphenyl)aminyl-4-amine, dibenzylaniline, etc. aromatic tertiary amino compounds, aromatic tertiary diamino compounds such as N,N'-bis(3-methylphenyl)-N,N'-diphenylbenzidine, 3-(4'-dimethylaminophenyl)-5 1,2,4-triazine derivatives such as ,6-di-(4′-methoxyphenyl)-1,2,4-triazine, hydrazone derivatives such as 4-diethylaminobenzaldehyde-1,1-diphenylhydrazone, 2-phenyl -quinazoline derivatives such as 4-styryl-quinazoline, benzofuran derivatives such as 6-hydroxy-2,3-di(p-methoxyphenyl)benzofuran, p-(2,2-diphenylvinyl)-N,N-diphenylaniline, etc. α-stilbene derivatives, enamine derivatives, carbazole derivatives such as N-ethylcarbazole, hole transport compounds such as poly-N-vinylcarbazole and its derivatives, chloranil, quinone compounds such as bromoanthraquinone, tetracyanoquinodimethane compounds, fluorenone compounds such as 2,4,7-trinitrofluorenone and 2,4,5,7-tetranitro-9-fluorenone, electron transport compounds such as xanthone compounds and thiophene compounds, and groups consisting of the above compounds Examples thereof include polymers having a main chain or side chain. These charge-transporting compounds may be used singly or in combination of two or more.

The binder resin contained in the charge transport layer includes, for example, polycarbonate (eg, bisphenol A or bisphenol Z type polycarbonate), acrylic resin, methacrylic resin, polyarylate, polyester, polyvinyl chloride, polystyrene, acrylonitrile-styrene copolymer. Polymer resin, acrylonitrile-butadiene copolymer resin, polyvinyl acetate, polyvinyl formal, polysulfone, styrene-butadiene copolymer resin, vinylidene chloride-acrylonitrile copolymer resin, vinyl chloride-vinyl acetate-maleic anhydride resin, silicone Insulating resins such as resins, phenol-formaldehyde resins, polyacrylamides, polyamides and chlorine rubbers, and organic photoconductive polymers such as polyvinylcarbazole, polyvinylanthracene and polyvinylpyrene. Among these binder resins, polycarbonate is preferable, and a polycarbonate copolymer having a solubility parameter calculated by the Feders method of 11.40 or more and 11.75 or less is particularly preferable. These binder resins may be used alone or in combination of two or more. The mixing ratio of the charge-transporting compound and the binder resin is desirably 10:1 to 1:5 in mass ratio.

The charge-transporting layer may contain additives such as antioxidants, ultraviolet absorbers, plasticizers, leveling agents, lubricity imparting agents, and abrasion resistance improvers. Specifically, hindered phenol compounds, hindered amine compounds, sulfur compounds, phosphorus compounds, benzophenone compounds, siloxane-modified resins, silicone oils, fluororesin particles, polystyrene resin particles, polyethylene resin particles, silica particles, alumina particles, boron nitride particles. etc.

Formation of the charge transport layer is not particularly limited, and a well-known formation method is used. It is done by heating according to.

As a method for applying the charge transporting layer coating solution, for example, usual methods such as dip coating, thrust coating, wire bar coating, spray coating, blade coating, knife coating and curtain coating can be used. .

When the particles are dispersed in the charge-transporting layer coating liquid, media dispersing machines such as ball mills, vibrating ball mills, attritors, sand mills, and horizontal sand mills, and media such as stirring, ultrasonic dispersing machines, roll mills, and high-pressure homogenizers are used. A less disperser is utilized. Examples of high-pressure homogenizers include a collision system in which a dispersion liquid is dispersed by liquid-liquid collision or liquid-wall collision in a high pressure state, and a penetration system in which a fine flow path is penetrated and dispersed in a high pressure state.

The film thickness of the charge transport layer is set, for example, preferably in the range of 5 μm to 50 μm, more preferably 10 μm to 30 μm.

<Process Cartridge and Electrophotographic Apparatus>
A process cartridge according to the present disclosure is a process cartridge that is detachably attached to an electrophotographic apparatus main body. Further, the process cartridge integrally supports the electrophotographic photosensitive member according to the present disclosure and at least one means selected from the group consisting of charging means, exposure means, developing means, transfer means and cleaning means. characterized by

Further, an electrophotographic apparatus according to the present disclosure is characterized by having the electrophotographic photoreceptor, charging means, exposure means, developing means, and transfer means according to the present disclosure.

FIG. 2 shows an example of a schematic configuration of an electrophotographic apparatus equipped with a process cartridge having the electrophotographic photoreceptor of the present disclosure.

In FIG. 2, reference numeral 200 denotes an electrophotographic apparatus, and 201 denotes a cylindrical (drum-shaped) electrophotographic photosensitive member of the present disclosure, which is driven to rotate about a shaft 202 in the direction of the arrow at a predetermined peripheral speed (process speed). be done. The surface (peripheral surface) of the electrophotographic photosensitive member 201 is positively or negatively charged by a charging means (primary charging means) 203 during the rotation process. Next, the surface of the electrophotographic photosensitive member 201 is irradiated with exposure light (image exposure light) 204 output from exposure means (image exposure means) (not shown). The exposure light 204 is intensity-modulated in correspondence with the time-series electrical digital image signal of the target image information. Examples of exposure means include slit exposure and laser beam scanning exposure. Thus, an electrostatic latent image corresponding to the desired image information is formed on the surface of the electrophotographic photosensitive member 201 .

The electrostatic latent image formed on the surface of the electrophotographic photosensitive member 201 is then developed (regular development or reversal development) with toner accommodated in developing means 205 to form a toner image. A toner image formed on the surface of the electrophotographic photosensitive member 201 is transferred to a transfer material 207 by transfer means 206 . Here, when the transfer material 207 is paper, it is taken out from a paper supply unit (not shown) in synchronism with the rotation of the electrophotographic photosensitive member 201 and fed between the electrophotographic photosensitive member 201 and the transfer means 206 . be done. Also, a bias voltage having a polarity opposite to the charge held by the toner is applied to the transfer means 206 from a bias power source (not shown). Alternatively, the transfer unit 206 may be an intermediate transfer type transfer unit 206 having a primary transfer member, an intermediate transfer member and a secondary transfer member.

The transfer material 207 onto which the toner image has been transferred is separated from the surface of the electrophotographic photosensitive member 201, conveyed to fixing means 208, and subjected to fixing processing of the toner image, whereby an image formed product (print, copy) is electronically produced. Printed out outside the photographic device.

After the toner image has been transferred, the surface of the electrophotographic photosensitive member 201 is cleaned by a cleaning means 209 to remove deposits such as transfer residual toner. The transfer residual toner can also be collected by the developing means 205 or the like. Furthermore, if necessary, the surface of the electrophotographic photosensitive member 201 is repeatedly used for image formation after being subjected to static elimination treatment by irradiation with pre-exposure light 210 from a pre-exposure unit (not shown). Incidentally, when the charging means 203 is a contact charging means using a charging roller or the like, the pre-exposure means is not necessarily required.

In the present disclosure, a plurality of components selected from the electrophotographic photosensitive member 201, the charging means 203, the developing means 205, the transfer means 206, the cleaning means 209, and the like may be housed in a container to form the process cartridge 211. . Alternatively, the process cartridge 211 may be detachably attached to the main body of the electrophotographic apparatus. For example, the electrophotographic photosensitive member 201 and at least one means selected from the group consisting of the charging means 203, the developing means 205, the transfer means 206 and the cleaning means 209 can be integrally supported to form a cartridge. Then, a guide means 212 such as a rail of the electrophotographic apparatus main body can be used to form a process cartridge 211 detachably attachable to the electrophotographic apparatus main body.

EXAMPLES Hereinafter, the present disclosure will be described in more detail with examples and comparative examples. In addition, "part" in an Example means "mass part."

<Example 1>
<Undercoat layer>
Zinc oxide: 100 parts of zinc oxide (average particle size: 70 nm, specific surface area: 15 m ² /g, manufactured by Tayca) was stirred and mixed with 500 parts of toluene, and a silane coupling agent (trade name: KBM503, manufactured by Shin-Etsu Chemical Co., Ltd.) was added at 1.3. were added and stirred for 2 hours. After that, toluene was distilled off under reduced pressure, and baking was carried out at 120° C. for 3 hours to obtain silane coupling agent surface-treated zinc oxide.

110 parts of surface-treated zinc oxide was stirred and mixed with 500 parts of tetrahydrofuran, a solution of 0.6 parts of alizarin dissolved in 50 parts of tetrahydrofuran was added, and the mixture was stirred at 50° C. for 5 hours. After that, the alizarin-imparted zinc oxide was separated by filtration under reduced pressure and dried under reduced pressure at 60° C. to obtain alizarin-imparted zinc oxide.

60 parts of alizarin-imparted zinc oxide, 13.5 parts of curing agent (blocked isocyanate Sumidur 3175, manufactured by Sumitomo Bayern Urethane Co., Ltd.), 15 parts of butyral resin (S-Lec BM-1, manufactured by Sekisui Chemical Co., Ltd.), and 85 parts of methyl ethyl ketone were mixed to obtain a mixed liquid. Then, 38 parts of the mixed liquid and 25 parts of methyl ethyl ketone were mixed, and dispersed for 2 hours in a sand mill using glass beads of 1 mmφ to obtain a dispersion liquid. Dioctyltin dilaurate: 0.005 part and silicone resin particles (Tospearl 145, manufactured by GE Toshiba Silicone Co., Ltd.): 1 part were added as a catalyst to the obtained dispersion liquid to obtain an undercoat layer coating liquid.

A cylindrical aluminum support having a diameter of 30 mm, a length of 357.5 mm and a thickness of 1 mm was prepared as a conductive support, and the resulting undercoat layer coating solution was applied onto the cylindrical aluminum support by a dip coating method. Then, it was dried and cured at 170° C. for 40 minutes to form an undercoat layer having a thickness of 18 μm.

<Charge generation layer>
Next, a mixture of the following materials was dispersed for 4 hours in a sand mill using glass beads with a diameter of 1 mm.
・Charge-generating substance: positions where the Bragg angles (2θ±0.2°) in the X-ray diffraction spectrum using Cukα characteristic X-rays are at least 7.3°, 16.0°, 24.9°, and 28.0° Hydroxygallium phthalocyanine having a diffraction peak at 15 parts Binder resin: Vinyl chloride/vinyl acetate copolymer resin (VMCH, manufactured by Nihon Unicar) 10 parts n-Butyl acetate 200 parts 175 parts of butyl and 180 parts of methyl ethyl ketone were added and stirred to obtain a charge generation layer coating solution. The charge generation layer coating solution thus obtained was dip-coated on the undercoat layer previously formed on the cylindrical aluminum support and dried at room temperature (25° C.) to form a charge generation layer having a thickness of 0.17 μm. bottom.

<First charge transport layer>
Next, the following materials were added to 560 parts of tetrahydrofuran and 240 parts of toluene and dissolved to obtain a charge transport layer coating solution.
・N,N′-diphenyl-N,N′-bis(3-methylphenyl)-[1,1′]biphenyl-4,4′-diamine (TPD) 40 parts ・N,N-bis(3,4 -Dimethylphenyl)biphenyl-4-amine 10 parts Binder resin: Bisphenol Z polycarbonate resin (Mitsubishi Gas Co., Ltd.: viscosity average molecular weight: 60,000, weight average molecular weight: 50,000) 55 parts It was applied onto the charge generation layer and dried at 135° C. for 45 minutes to form a first charge transport layer having a thickness of 22 μm.

<Surface layer (second charge transport layer)>
First, 2 parts of S-LEC BM-1 (manufactured by Sekisui Chemical Co., Ltd., hydroxyl group content: 34 mol%, butyralization degree: 65±3 mol%, molecular weight: 40000) as a polyvinyl acetal was dissolved in 36 parts of 1-propanol with sufficient stirring. Subsequently, 10 parts of polytetrafluoroethylene particles (trade name: Lubron L2, manufactured by Daikin Industries, Ltd.) were added as fluororesin particles, and the mixture was stirred and mixed to obtain a mixture. The resulting mixed solution of polytetrafluoroethylene particles is placed in a high-pressure disperser (trade name: Microfluidizer M-110EH, manufactured by Microfluidics, Inc., USA) and passed six times at a pressure of 40 MPa to obtain fluororesin particles. A dispersion was obtained. The average particle size of the fluororesin particles in the obtained fluororesin particle dispersion was 0.18 μm.

Next, the following materials were mixed and dissolved to obtain a solution.
・Charge-transporting compound: Compound (B-3) 87 parts ・Antioxidant: 3,5-di-t-butyl-4-hydroxytoluene 0.8 parts ・Dodecylbenzenesulfonic acid 0.2 parts ・1-propanol 64 parts/50 parts of cyclopentanol Then, the above fluororesin particle dispersion was added to the solution to obtain a surface layer coating solution. The average particle size of the fluororesin particles in the resulting surface layer coating liquid was 0.18 μm.

This surface layer coating solution was applied onto the first charge transport layer by dip coating, air-dried at room temperature (25° C.) for 30 minutes, and then cured by heat treatment at 150° C. for 1 hour to form a film having a thickness of 10 μm. A surface layer (second charge transport layer) was formed to prepare an electrophotographic photoreceptor.

Thus, an electrophotographic photoreceptor 1 having a support, an undercoat layer, a charge generation layer, a charge transport layer and a surface layer in this order was produced. Physical properties are shown in Table 2.

<Evaluation>
<Evaluation of image reproducibility>
As an evaluation apparatus, a color multifunction machine (trade name: iR AVD C5051 (process speed: 246 mm/sec), manufactured by Canon Inc.) was used. First, the produced electrophotographic photosensitive member 1 was mounted on the cyan station of the evaluation apparatus, and the following operations were performed under the environment of temperature of 23° C. and humidity of 60% RH.

First, a horizontal A4 image with 17 gradations and an output resolution of 600 dpi was formed, and the resulting A4 image was visually observed and evaluated according to the following evaluation criteria. Those with an evaluation of A or B were judged to have good image reproducibility. Table 2 shows the evaluation results.

A: Good image reproducibility with no vertical streaks.

B: Slight vertical streaks are observed in some parts when observed under magnification, but image reproducibility is good in other parts.

C: Generation of vertical streaks is observed when observed under magnification.

D: Clear vertical streaks are observed by visual observation, and the image reproducibility is low.

Subsequently, an endurance test was conducted in which 10,000 sheets of A4 paper were continuously printed with a character image having an image ratio of 5%. Then, an A4 landscape image with 17 gradations and an output resolution of 600 dpi was formed again, and the resulting A4 image was visually observed and evaluated according to the same evaluation criteria as above. Table 2 shows the evaluation results. It was judged that the effects of the present disclosure were obtained when the evaluation was A or B both before and after the durability test.

<Abrasion resistance evaluation>
After the above evaluation, the electrophotographic photoreceptor 1 was taken out, and the wear amount of the surface layer of the photoreceptor before and after the durability test was measured. An eddy current film thickness meter (manufactured by Kett Science Laboratory) was used to measure the film thickness. It was judged that the effects of the present disclosure were obtained when the amount of wear was 1.0 μm or less. Table 2 shows the evaluation results.

<Example 2>
First, the same operation as in Example 1 was performed to form the undercoat layer to the first charge transport layer.

Subsequently, 2 parts of S-LEC BM-1 as a polyvinyl acetal was added to 36 parts of 1-propanol, and thoroughly stirred and dissolved. Then, 10 parts of Lublon L2 was added as fluororesin particles and mixed with stirring to obtain a mixture of polytetrafluoroethylene particles. The resulting mixed solution of polytetrafluoroethylene particles is placed in a high-pressure disperser (trade name: Microfluidizer M-110EH, manufactured by Microfluidics, USA) and passed six times at a pressure of 40 MPa to obtain a fluororesin particle dispersion. Obtained. The average particle size of the fluororesin particles in the obtained fluororesin particle dispersion was 0.18 μm.

Next, the following materials were mixed and dissolved to obtain a solution.
- Charge-transporting compound: Compound (B-3) 80 parts - Benzoguanamine compound represented by the following formula (3) 7 parts

· Antioxidant: 0.8 parts of 3,5-di-t-butyl-4-hydroxytoluene · 0.2 parts of dodecylbenzenesulfonic acid · 64 parts of 1-propanol · 50 parts of cyclopentanol To the resulting solution , the above fluororesin particle dispersion was added to obtain a surface layer coating liquid. The average particle size of the fluororesin particles in the resulting surface layer coating liquid was 0.18 μm.

This surface layer coating solution was applied onto the first charge transport layer by dip coating, air-dried at room temperature (25° C.) for 30 minutes, and then cured by heat treatment at 150° C. for 1 hour to form a surface having a film thickness of 10 μm. A layer was formed, and an electrophotographic photoreceptor 2 was produced. Physical properties are shown in Table 2.

Using the produced electrophotographic photoreceptor 2, the same evaluation as in Example 1 was performed. Table 2 shows the evaluation results.

<Example 3>
An electrophotographic photoreceptor 3 was prepared and evaluated in the same manner as in Example 2, except that the benzoguanamine compound represented by formula (3) was changed to the melamine compound represented by formula (4) below. Table 2 shows the physical properties and evaluation results of the electrophotographic photoreceptor.

<Example 4>
The same operation as in Example 2 was performed except that the benzoguanamine compound represented by the formula (3) was changed to a phenol compound (trade name: PL-4852, manufactured by Gunei Chemical Industry Co., Ltd.). Body 4 was produced and evaluated. Table 2 shows the physical properties and evaluation results of the electrophotographic photoreceptor.

<Examples 3 to 9>
As shown in Table 2, electrophotographic photoreceptors 5 to 9 were produced and evaluated in the same manner as in Example 2, except that the materials were changed. Table 2 shows the physical properties and evaluation results of the electrophotographic photoreceptor.

<Examples 10 to 16>
In Example 2, electrophotographic photoreceptors 10 to 16 were produced and evaluated in the same manner as in Example 2, except that the amount of each material added was changed as shown in Table 1. Table 2 shows the physical properties and evaluation results of the electrophotographic photoreceptor.

<Comparative Example 1>
An electrophotographic photoreceptor 17 was produced and evaluated in the same manner as in Example 2, except that S-LEC BM-1 was not used. Table 2 shows the physical properties and evaluation results of the electrophotographic photoreceptor.

<Comparative Example 2>
First, the same operation as in Example 1 was performed to form the undercoat layer to the first charge transport layer. In addition, methanol was added dropwise to a solution of a fluorine-based graft polymer (trade name: GF400, Toagosei Co., Ltd.), and the precipitated product was collected to obtain a fluorine-based graft polymer (FG1).

After sufficiently stirring and dissolving 2 parts of the fluorine-based graft polymer (FG1) in 36 parts of 1-propanol, polytetrafluoroethylene particles (trade name: Lubron L2, manufactured by Daikin Industries, Ltd.) are added as fluororesin particles. 10 parts were added and further stirred and mixed to obtain a mixed liquid. The resulting mixed solution was placed in a high-pressure disperser (trade name: Microfluidizer M-110EH, manufactured by Microfluidics, Inc., USA) and passed six times at a pressure of 40 MPa to obtain a fluororesin particle dispersion. The average particle size of the fluororesin particles in the obtained fluororesin particle dispersion was 0.18 μm.

Subsequently, the following materials were mixed and dissolved to obtain a solution.
- Charge-transporting compound: Compound (B-3) 80 parts - Benzoguanamine compound represented by the above formula (3) 7 parts - Antioxidant: 3,5-di-t-butyl-4-hydroxytoluene 0.8 parts 0.2 parts of dodecylbenzenesulfonic acid 64 parts of 1-propanol 50 parts of cyclopentanol Then, the above fluororesin particle dispersion was added to the solution to obtain a surface layer coating solution. The average particle size of the fluororesin particles in the resulting surface layer coating liquid was 0.35 μm.

This surface layer coating solution was applied onto the first charge transport layer by dip coating, air-dried at room temperature (25° C.) for 30 minutes, and then cured by heat treatment at 150° C. for 1 hour to form a film having a thickness of 10 μm. A surface layer (second charge transport layer) was formed, and an electrophotographic photoreceptor 18 was produced. Also, the same evaluation as in Example 1 was performed using the produced electrophotographic photoreceptor 18 . Table 2 shows the physical properties and evaluation results of the electrophotographic photoreceptor 18 .

<Comparative Example 3>
First, the same operation as in Example 1 was performed to form the undercoat layer to the first charge transport layer. Further, 2 parts of S-LEC BM-1 as polyvinyl acetal and 36 parts of 1-propanol were thoroughly stirred and dissolved to obtain a polyvinyl acetal solution.

Subsequently, the following materials were mixed and dissolved to obtain a solution.
- Charge-transporting compound: Compound (B-3) 80 parts - Benzoguanamine compound represented by the above formula (3) 7 parts - Antioxidant: 3,5-di-t-butyl-4-hydroxytoluene 0.8 parts 0.2 parts of dodecylbenzenesulfonic acid 64 parts of 1-propanol 50 parts of cyclopentanol Then, the polyvinyl acetal solution was added to the solution to obtain a surface layer coating solution.

This surface layer coating solution was applied onto the first charge transport layer by dip coating, air-dried at room temperature (25° C.) for 30 minutes, and then cured by heat treatment at 150° C. for 1 hour to form a surface having a film thickness of 10 μm. Layers were formed to produce an electrophotographic photoreceptor 19 . Also, the same evaluation as in Example 1 was performed using the produced electrophotographic photoreceptor 19 . Table 2 shows the physical properties and evaluation results of the electrophotographic photoreceptor 19 .

<Comparative Example 4>
An electrophotographic photoreceptor 20 was produced and evaluated in the same manner as in Example 2, except that the compound (B-3) was changed to the compound represented by the following formula (5). Physical properties are shown in Table 1, and evaluation results are shown in Table 2.

Abbreviations in Table 2 are as follows.
L2: fluororesin particles (trade name: Lebron L2, manufactured by Daikin Industries, Ltd.)
L5: fluororesin particles (trade name: Lebron L5, manufactured by Daikin Industries, Ltd.)
BM-1: Polyvinyl butyral (trade name: S-lec BM-1, manufactured by Sekisui Chemical Co., Ltd., hydroxyl group content 34 mol%, butyralization degree 65 ± 3 mol%, molecular weight 40000)
BL-10: Polyvinyl butyral (trade name: S-lec BL-10, manufactured by Sekisui Chemical Co., Ltd., hydroxyl content 28 mol%, butyralization degree 71 ± 3 mol%, molecular weight about 15000)
GF400: Fluorine-based graft polymer (trade name: GF400, Toagosei Co., Ltd.) (*Not applicable to polyvinyl acetal, but listed in the polyvinyl acetal column.)
Guanamine: a benzoguanamine compound represented by the above formula (3) Melamine: a melamine compound represented by the above formula (4) Phenol: a phenol compound (trade name: PL-4852, manufactured by Gunei Chemical Industry Co., Ltd.)

REFERENCE SIGNS LIST 101 support 102 charge generation layer 103 (first) charge transport layer 104 second charge transport layer 105 photosensitive layer 106 electrophotographic photoreceptor 200 electrophotographic apparatus 201 electrophotographic photoreceptor 202 axis 203 charging means 204 exposure light 205 development Means 206 Transfer Means 207 Transfer Material 208 Fixing Means 209 Cleaning Means 210 Pre-exposure Light 211 Process Cartridge 212 Guiding Means

Claims (12)

An electrophotographic photoreceptor comprising a support and a photosensitive layer on the support,
An electrophotographic photoreceptor, wherein the surface layer of the electrophotographic photoreceptor is a polymer film of a composition containing fluororesin particles, a charge-transporting compound having two or more hydroxyalkyl groups, and polyvinyl acetal. . 2. The electrophotographic photoreceptor of claim 1, wherein said polyvinyl acetal is polyvinyl butyral. 3. The electrophotographic photoreceptor according to claim 1, wherein said polyvinyl acetal contains a hydroxy group. 4. The electrophotographic photoreceptor according to claim 1, wherein said hydroxyalkyl group is a hydroxymethyl group. 5. The electrophotographic photoreceptor according to claim 1, wherein the charge-transporting compound has 3 or more hydroxyalkyl groups. 6. The electrophotographic photoreceptor according to claim 1, wherein the composition further contains at least one compound selected from the group consisting of phenolic compounds, melamine compounds and benzoguanamine compounds. The content of the polyvinyl acetal in the composition is 20.0% by mass or more and 50.0% by mass or less with respect to the content of the fluororesin particles, according to any one of claims 1 to 6 The electrophotographic photoreceptor described. The content of the fluororesin particles in the composition is 1.0% by mass or more and 40.0% by mass or less with respect to the total mass of the composition, according to any one of claims 1 to 7 The electrophotographic photoreceptor described. the photosensitive layer has a charge generation layer, a first charge transport layer and a second charge transport layer in this order;
the second charge transport layer is the surface layer;
The electrophotographic photoreceptor according to any one of claims 1 to 8. A method for producing an electrophotographic photoreceptor,
preparing a surface layer coating liquid containing a composition containing fluororesin particles, a charge-transporting compound having two or more hydroxyalkyl groups, and polyvinyl acetal;
a step of forming a coating film of the surface layer coating liquid; and a step of forming a surface layer of an electrophotographic photoreceptor by polymerizing the coating film;
A method for producing an electrophotographic photoreceptor, comprising: A process cartridge detachable from an electrophotographic apparatus main body,
The process cartridge comprises the electrophotographic photosensitive member according to any one of claims 1 to 9, and at least one means selected from the group consisting of charging means, exposure means, developing means, transfer means and cleaning means. and integrally supporting the process cartridge. An electrophotographic apparatus comprising the electrophotographic photosensitive member according to any one of claims 1 to 9, charging means, exposure means, developing means, and transfer means.

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