CN117460997A

CN117460997A - Electrophotographic photosensitive member, process cartridge, and electrophotographic apparatus

Info

Publication number: CN117460997A
Application number: CN202280041733.2A
Authority: CN
Inventors: 渡边俊太郎; 石田知仁; 中村延博; 渡部博之; 山合达也; 广田匡纪
Original assignee: Canon Inc
Current assignee: Canon Inc
Priority date: 2021-06-11
Filing date: 2022-06-09
Publication date: 2024-01-26

Abstract

An electrophotographic photosensitive member capable of achieving improvement in transferability and improvement in image quality of halftone images by suppressing light scattering on a surface layer of the electrophotographic photosensitive member is provided. The electrophotographic photosensitive member includes a support and a photosensitive layer on the support, wherein the electrophotographic photosensitive member is characterized in that: the surface layer of the electrophotographic photosensitive member contains particles; among the particles contained in the surface layer, the surface layer has particles partially exposed from the surface layer; the volume average particle diameter of the particles is 50.0nm or more and 350.0nm or less; in a cross section of the surface layer, the number of particles partially exposed from the surface layer is 80% or more relative to all particles contained in the surface layer; and the total volume of the exposed portion of the particles partially exposed from the surface layer is 30% by volume or more and 80% by volume or less with respect to the total volume of the particles contained in the surface layer.

Description

Electrophotographic photosensitive member, process cartridge, and electrophotographic apparatus

Technical Field

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

Background

In recent years, high-speed printing has been demanded in the field of electrophotographic apparatuses such as copying machines and printers to improve productivity. In order to achieve high speeds in electrophotographic apparatuses, the latent image generated in the exposure step must be developed to toner in the development step, and in repetition of charging, exposure, development, and transfer steps of the electrophotographic process, the toner must be efficiently transferred to media such as paper and intermediate transfer media. From the viewpoint of effective use of office space, there is also an increasing demand for small electrophotographic apparatuses in which the cleaning step is omitted by improving the efficiency of the transfer step.

In the transfer step, a predetermined bias is applied to the toner so as to transfer the toner obtained by developing the latent image on the photosensitive member to the medium. By adding an external additive to the toner and forming a specific shape on the surface of the photosensitive member, the adhesion of the toner to the surface of the photosensitive member can be reduced, thereby reducing the applied bias. This can not only save space for a high-voltage power supply for applying a high bias in an electrophotographic apparatus, but also suppress scattering of toner due to a high transfer bias, thereby achieving improvement in image quality. As one method of reducing the adhesion of toner to the surface of the photosensitive member by forming a specific shape on the surface of the photosensitive member, it has conventionally been proposed to form a convex shape on the surface of the electrophotographic photosensitive member by including particles on the surface in order to form a point contact between the toner and the surface of the photosensitive member.

Patent document 1 discloses an electrophotographic photosensitive member having a convex structure on the surface of an outermost layer composed of a polymerizable monomer and a polymerization cured product of a composition including an inorganic filler, with the aim of improving cleaning performance and reducing abrasion of the photosensitive member and cleaning blade, regardless of the amount of lubricant supplied.

Patent document 2 discloses an electrophotographic photosensitive member having a surface layer formed by curing a coating film containing organic resin particles, which are at least one of acrylic resin particles and melamine resin particles, and a hole transporting compound having a polymerizable functional group, in order to make the photosensitive member surface abrasion resistant and highly lubricating.

Patent document 3 discloses an electrophotographic photosensitive member containing a curable resin and polytetrafluoroethylene particles and having a concave-convex shape formed by mechanical polishing on the surface of a surface layer, the purpose of which is to reduce image unevenness caused by uneven gloss of a support while maintaining abrasion resistance.

Patent document 4 discloses an electrophotographic photosensitive member containing encapsulated spherical particles encapsulated in pores of a matrix component, with the aim of improving lubricity and cleaning properties of the photosensitive member surface.

Patent document 5 discloses an electrophotographic photosensitive member in which, in order to maintain a releasing effect, independent concave-shaped portions having a depth of 0.1 μm or more and 10 μm or less are formed on the surface of the surface layer of the photosensitive member, and a releasing material is contained in the concave-shaped portions.

[ Prior Art literature ]

[ patent literature ]

Patent document 1: japanese patent application laid-open No.2020-71423

Patent document 2: japanese patent application laid-open No.2019-45862

Patent document 3: japanese patent application laid-open No.2016-118628

Patent document 4: japanese patent application laid-open No.2013-029812

Patent document 5: japanese patent application laid-open No. 2009-14015

Disclosure of Invention

Problems to be solved by the invention

In recent electrophotographic apparatuses, there is a demand for both improving the efficiency of the transfer process to reduce waste toner for handling environmental problems and obtaining higher image quality at higher output speeds. However, in patent documents 1 to 3, although the adhesion between the toner and the surface of the photosensitive member is reduced to some extent and the transferability of the toner is improved, it has been found that laser scattering during exposure of the photosensitive member is not possible to maintain uniformity of the halftone image due to the multilayer lamination of fine particles in the surface layer. Further, in patent document 4, when there is a peripheral speed difference between the photosensitive member and the intermediate transfer medium or media during transfer, the encapsulated spherical particles move, the contact area between the toner and the surface of the photosensitive member increases, resulting in a phenomenon of reduced transferability. In the case of patent document 5, a plurality of release materials are contained in the concave portion, and point contact between the toner and the surface of the photosensitive member cannot be maintained, making it difficult to maintain good transferability for a long period of time.

An object of the present invention is to provide a photosensitive member that achieves both improvement of image quality and improvement of transferability of halftone images by suppressing light scattering of a surface layer of the photosensitive member.

Solution for solving the problem

The above object is achieved by the following invention.

Specifically, an electrophotographic photosensitive member according to the present invention includes a support and a photosensitive layer on the support,

wherein the surface layer of the electrophotographic photosensitive member contains particles,

the surface layer has particles partially exposed from the surface layer among particles contained in the surface layer,

the volume average particle diameter of the particles is 50.0nm or more and 350.0nm or less;

in the cross section of the surface layer, the number of particles partially exposed from the surface layer is 80% or more based on the total number of particles contained in the surface layer; and

the total volume of the exposed portion of the particles partially exposed from the surface layer is 30% by volume or more and 80% by volume or less based on the entire volume of the particles contained in the surface layer.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, the electrophotographic photosensitive member can achieve both improvement of image quality and improvement of transferability of a halftone image by suppressing light scattering of the surface layer of the photosensitive member.

Drawings

Fig. 1 is a conceptual view of the constitution of each layer in a cross section of a photosensitive member.

Fig. 2 is a conceptual view of the layer constitution in the cross section of the photosensitive member.

Fig. 3 is a conceptual view of the layer constitution in the cross section of the photosensitive member.

Fig. 4 is a conceptual view of an exposed area of the particles when the photosensitive member is viewed from above.

Fig. 5 is a conceptual view showing an electrophotographic apparatus.

Fig. 6 is a conceptual view showing an exposed volume of particles in a surface layer of the photosensitive member.

Detailed Description

Hereinafter, preferred embodiments of the present invention will be described.

[ electrophotographic photosensitive Member ]

An electrophotographic photosensitive member according to the present invention includes a support, a photosensitive layer provided on the support, and a surface layer containing particles. The electrophotographic photosensitive member according to the present invention can be used as a cylindrical electrophotographic photosensitive member in which a photosensitive layer and a surface layer are formed on a cylindrical support, and can also be used in the form of a belt or sheet.

The electrophotographic photosensitive member according to the present invention is used in an image forming method including a charging step of charging a surface of the electrophotographic photosensitive member, an exposing step of exposing the charged electrophotographic photosensitive member to light to form an electrostatic latent image, a developing step of supplying toner to the electrophotographic photosensitive member on which the electrostatic latent image is formed to form a toner image, and a transferring step of transferring the toner image formed on the electrophotographic photosensitive member.

The method for producing an electrophotographic photosensitive member according to the present invention comprises: preparing coating liquid of each layer; coating the coating liquid in a desired layer sequence; and a method of drying the coated coating liquid. In this case, examples of a method of coating each coating liquid include dip coating, spray coating, inkjet coating, roll coating, die coating, blade coating, curtain coating, bar coating, and ring coating. Among them, dip coating is preferable from the viewpoint of efficiency and productivity.

The present invention provides an electrophotographic photosensitive member including a support and a photosensitive layer on the support, wherein a surface layer of the electrophotographic photosensitive member contains particles, the surface layer has particles partially exposed from the surface layer among the particles contained in the surface layer, and the electrophotographic photosensitive member satisfies the following three conditions:

(i) The volume average particle diameter of the particles is 50.0nm or more and 350.0nm or less.

(ii) In the cross section of the surface layer, the number of particles partially exposed from the surface layer is 80% or more based on the total number of particles contained in the surface layer.

(iii) The total volume of the exposed portion of the particles partially exposed from the surface layer is 30% by volume or more and 80% by volume or less based on the entire volume of the particles contained in the surface layer.

Although the mechanism for solving the problem by the above constitution is not clear, the present inventors speculate as follows.

In order to improve transferability of an electrophotographic apparatus, it is necessary to reduce adhesion between a toner and an electrophotographic photosensitive member. The adhesion between the toner and the electrophotographic photosensitive member can be roughly classified into electrostatic and non-electrostatic adhesion forces. The electrostatic adhesion force largely depends on the charge amount of the toner, because the reflection force is a main factor. The magnitude of the reflection force is proportional to the charge amount of the toner and inversely proportional to the square of the distance of the photosensitive member surface to which the toner is attached. From the viewpoint of securing a distance between the toner and the surface of the photosensitive member, particles are generally arranged in the surface layer of the photosensitive member to attenuate the reflection force.

However, in order to arrange particles in the surface layer of the photosensitive member, a conventional technique generally employs a constitution in which the particles are mixed into a resin forming the surface layer to expose a partial number of particles with respect to the total number of particles. Therefore, it has been found that the amount of particles in the surface layer of the photosensitive member is excessive, light scattering occurs in the surface layer of the photosensitive member in the exposure step of forming an electrostatic latent image in the electrophotographic apparatus, and the formation of the latent image in the halftone image becomes uneven.

In the electrophotographic photosensitive member of the present invention, in order to suppress light scattering, the surface layer of the photosensitive member needs to have particles partially exposed from the surface layer among particles contained in the surface layer. Further, in the cross section of the surface layer, the number of particles partially exposed from the surface layer needs to be 80% or more based on the total number of particles contained in the surface layer. As a result, light scattering is suppressed, and reproducibility of the latent image is improved. When the number of the partially exposed particles is less than 80% by number based on the total number of the particles contained in the surface layer, uniformity of the halftone image is deteriorated. The number of particles is more preferably 85% by number or more, even more preferably 90% by number or more. Here, the particles contained in the surface layer refer to particles partially exposed from the surface layer and particles of a portion not exposed from the surface layer.

Meanwhile, in order to reduce the above non-electrostatic adhesion force, it is also required to reduce van der waals force. In order to reduce the van der waals force, it is effective to geometrically reduce the contact area between the toner and the electrophotographic photosensitive member. In this case, the particles contained in the surface layer of the electrophotographic photosensitive member according to the present invention are preferably required to have a volume average particle diameter of 50.0nm or more and 350.0nm or less. It is conceivable that by using particles having such a volume average particle diameter, the curvature of the particles partially exposed in the surface layer of the photosensitive member is increased, thereby minimizing van der Waals forces on the surface curvature of the toner. The volume average particle diameter is more preferably 70.0nm or more and 250.0nm or less, even more preferably 90.0nm or more and 200.0nm or less.

Further, the particle size distribution is preferably within a certain range because the effect of reducing the adhesion between the photosensitive member and the toner varies as the variation in the particle size distribution increases. Note that in the present invention, the volume average particle diameter and the number average particle diameter of the particles are measured with an apparatus capable of measuring particle diameters by dynamic light scattering. The (volume average particle diameter)/(number average particle diameter) obtained by dividing the volume average particle diameter of the particles by the number average particle diameter is preferably 1.5 or less, more preferably 1.4 or less, and even more preferably 1.3 or less.

In order to achieve a higher level of light scattering reduction in the exposure step while reducing the non-electrostatic adhesion force with the toner, it is necessary to use an electrophotographic photosensitive member in which the total volume of the exposed portions of the particles partially exposed from the surface layer is 30% by volume or more and 80% by volume or less based on the total volume of the particles contained in the surface layer. If it exceeds 80% by volume, the exposed volume of the particles becomes too large, and the particles tend to fall off from the surface layer of the photosensitive member due to repeated friction of the toner in the developing step. Further, when the total volume of the exposed portions of the particles partially exposed from the surface layer is less than 30% by volume based on the total volume of the particles contained in the surface layer, the contact area becomes large, resulting in deterioration of transferability and reduction of uniformity of the halftone image. For this reason, the total volume of the exposed portion of the particles partially exposed from the surface layer needs to be 30% by volume or more and 80% by volume or less, and more preferably 35% by volume or more and 77.5% by volume or less, even more preferably 37.5% by volume or more and 75.0% by volume or less, based on the entire volume of the particles contained in the surface layer. The exposed portion of the particles partially exposed from the surface layer may be previously coated with a resin or a surface treatment agent. As shown in fig. 6, the volume of the exposed portion of the particles partially exposed from the surface layer refers to the volume of the portion of the particles contained in the binder resin of the surface layer exposed from the surface of the resin portion of the surface layer.

The particles contained in the surface layer of the electrophotographic photosensitive member according to the present invention are not particularly limited. Examples of the particles include organic resin particles such as acrylic resin particles, inorganic particles such as alumina, silica, and titania, and organic-inorganic hybrid particles.

In addition, in order to improve the charge transporting ability of the surface layer, conductive particles or a charge transporting substance may be added to the coating liquid for the surface layer. As the conductive particles, conductive pigments used in a conductive layer described later can be used. As the charge transporting substance, a charge transporting substance which will be described later can be used. Additives may also be added for the purpose of improving various functions. Examples of the additives include conductive particles, antioxidants, ultraviolet absorbers, plasticizers, and leveling agents.

Examples of the organic resin particles include crosslinked polystyrene particles, crosslinked acrylic resin particles, phenolic resin particles, melamine resin particles, polyethylene particles, polypropylene particles, acrylic resin particles, polytetrafluoroethylene particles, and silicone particles.

The acrylic resin particles comprise a polymer of acrylate or methacrylate. Styrene-acrylic resin particles are more preferable among such particles. The polymerization degree of the acrylic resin, the styrene-acrylic resin, or the thermoplastic or thermosetting resin is not particularly limited.

The polytetrafluoroethylene particles may be particles composed mainly of tetrafluoroethylene resin, and may further contain chlorotrifluoroethylene resin, hexafluoropropylene resin, vinyl fluoride resin, vinylidene fluoride resin, or the like.

The organic-inorganic hybrid particles include polymethylsilsesquioxane particles that include siloxane bonds.

As the particles contained in the surface layer of the electrophotographic photosensitive member according to the present invention, inorganic particles that have low elasticity and are advantageous for point contact with toner are preferably used.

Inorganic particles include, for example, particles of magnesium oxide, zinc oxide, lead oxide, tin oxide, tantalum oxide, indium oxide, bismuth oxide, yttrium oxide, cobalt oxide, copper oxide, manganese oxide, selenium oxide, iron oxide, zirconium oxide, germanium oxide, tin oxide, titanium oxide, niobium oxide, molybdenum oxide, vanadium oxide, copper aluminum oxide, tin oxide doped with antimony ions, and hydrotalcite. These particles may be used alone or in combination of two or more. The inorganic particles are preferably silica particles.

Known silica particles may be used as the silica particles, which may be dry silica particles or wet silica particles. More preferably, the silica particles are wet silica particles obtained by a sol-gel method (hereinafter also referred to as "sol-gel silica").

The sol-gel silica used for the particles contained in the surface layer of the electrophotographic photosensitive member according to the present invention may be hydrophilic or a surface hydrophobizing treatment for the particles.

Examples of the hydrophobizing treatment method include a method of removing a solvent from a silica sol suspension in a sol-gel method, drying, and then treating with a hydrophobizing agent, and a method of directly adding a hydrophobizing agent to a silica sol suspension and treating simultaneously with drying. The technique of directly adding the hydrophobizing agent to the silica sol suspension is preferable from the viewpoints of controlling the half-value width of the particle size distribution and controlling the saturated moisture adsorption amount.

By the hydrophobization treatment of the particles contained in the surface layer of the electrophotographic photosensitive member according to the present invention, the exposed state of the particles in the surface layer can be controlled.

Examples of hydrophobizing agents include the following:

chlorosilanes such as methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, phenyltrichlorosilane, diphenyldichlorosilane, t-butyldimethylchlorosilane and vinyltrichlorosilane;

alkoxysilanes such as tetramethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, o-methylphenyl trimethoxysilane, p-methylphenyl trimethoxysilane, n-butyltrimethoxysilane, isobutyltrimethoxysilane, hexyltrimethoxysilane, octyltrimethoxysilane, decyltrimethoxysilane, dodecyltrimethoxysilane, tetraethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, diphenyldiethoxysilane, isobutyltriethoxysilane, decyltriethoxysilane, vinyltriethoxysilane, γ -methacryloxypropyl trimethoxysilane, γ -glycidoxypropyl methyldimethoxysilane, γ -mercaptopropyl trimethoxysilane, γ -chloropropyltrimethoxysilane, γ -aminopropyl trimethoxysilane, γ -aminopropyl triethoxysilane, γ - (2-aminoethyl) aminopropyl trimethoxysilane and γ - (2-aminoethyl) aminopropyl methyldimethoxysilane;

Silazanes, such as hexamethyldisilazane, hexaethyldisilazane, hexapropyldisilazane, hexabutyldisilazane, hexapentyldisilazane, hexahexyldisilazane, hexacyclohexyldisilazane, hexaphenyldisilazane, divinyl tetramethyl disilazane and dimethyl tetravinyl disilazane;

silicone oils such as dimethyl silicone oil, methyl hydrogen silicone oil, methyl phenyl silicone oil, alkyl-modified silicone oil, chloroalkyl-modified silicone oil, chlorophenyl-modified silicone oil, fatty acid-modified silicone oil, polyether-modified silicone oil, alkoxy-modified silicone oil, methanol-modified silicone oil, amino-modified silicone oil, fluorine-modified silicone oil, and terminal-reactive silicone oil;

silicones such as hexamethylcyclotrisiloxane, octamethyltetrasiloxane, decamethylcyclopentasiloxane, hexamethyldisiloxane and octamethyltrisiloxane; and

fatty acids and metal salts thereof, including, for example, undecanoic acid, lauric acid, tridecanoic acid, dodecanoic acid, myristic acid, palmitic acid, pentadecanoic acid, stearic acid, heptadecanoic acid, arachic acid, montanic acid, oleic acid, linoleic acid, and arachidonic acid, and salts of fatty acids with metals such as zinc, iron, magnesium, aluminum, calcium, sodium, and lithium.

Among them, alkoxysilanes, silazanes and silicone oils are preferably used because hydrophobization is easy to carry out. Such hydrophobizing agents may be used alone or in combination of two or more.

The particles contained in the surface layer of the electrophotographic photosensitive member according to the present invention preferably have a young's modulus of 0.60GPa or more. When the Young's modulus of the particle surface is less than 0.60GPa, the contact area between the surface of the toner and the surface of the particle becomes large when in contact with the toner, resulting in deterioration of transferability.

In the electrophotographic photosensitive member according to the present invention, when the surface layer is observed from above, S1/(s1+s2) (hereinafter also referred to as "coating ratio") preferably satisfies the following formula (a), where S1 is the total area of the exposed portions 401 of the particles and S2 is the total area other than the exposed portions 402 of the particles partially exposed from the surface layer, as shown in fig. 4:

S1/(S1+S2) 0.15.ltoreq.S 1/(S1+S2) 0.80

When the coating ratio is less than 0.15, the contact area between the surface of the toner and the portion of the photosensitive member surface other than the exposed portion of the particles becomes large, the adhesion increases, and the transferability deteriorates. When the coverage exceeds 0.80, the exposed portions of the particles in the surface of the photosensitive member increase, whereby the distance between the contact site of the toner and the particles contained in the surface layer of the photosensitive member tends to become shorter. As a result, the contact area between the toner and the particles contained in the surface layer of the photosensitive member becomes large, the adhesion increases, the transferability deteriorates, and the amount of adhesion of the toner increases during the endurance test of the electrophotographic photosensitive member. Therefore, the developability deteriorates, resulting in a decrease in the concentration. The coating ratio is more preferably in the range of 0.20 to 0.70, even more preferably in the range of 0.25 to 0.60.

The coefficient of variation of the coating ratio S1/(s1+s2) is preferably 25% or less. If the coefficient of variation exceeds 25%, unevenness occurs in the point contact state, resulting in deterioration of transferability. The coefficient of variation is more preferably 20% or less, even more preferably 15% or less.

In the electrophotographic photosensitive member according to the present invention, the average circularity of the shape of the exposed portion of the particles is preferably 0.90 or more when the surface layer is viewed from above.

If the average circularity is less than 0.90, point contact between the toner and the surface layer of the electrophotographic photosensitive member becomes difficult, and transferability deteriorates, resulting in scattering deterioration of points on an image. The average circularity of the shape of the exposed portion of the particles is more preferably 0.92 or more, even more preferably 0.94 or more.

In the electrophotographic photosensitive member according to the present invention, SF-2 of the shape of an exposed portion of particles described later is preferably 135 or less when the surface layer is observed from above. If SF-2 exceeds 135, point contact between the toner and the surface layer of the electrophotographic photosensitive member becomes difficult, and transferability deteriorates, resulting in scattering deterioration of points on an image.

In the electrophotographic photosensitive member according to the present invention, the ash content of the methyl ethyl ketone insoluble component in the surface layer during sintering is preferably 5.0 mass% or less based on the total mass of the surface layer. If the MEK insoluble component exceeds 5.0 mass%, light scattering on the photosensitive member surface increases, which may deteriorate the evaluation of the roughness of the halftone image. The MEK insoluble content is more preferably 4.5 mass% or less.

The electrophotographic photosensitive member according to the present invention may have several layer configurations.

Layer constitution 1: an electrophotographic photosensitive member includes a support 104 and a photosensitive layer on the support, wherein a surface layer of the electrophotographic photosensitive member contains particles 101, and the photosensitive layer has a charge generating layer 103 and a charge transporting layer 102 on the charge generating layer, the charge transporting layer being a surface layer (fig. 1).

Layer constitution 2: an electrophotographic photosensitive member includes a support 205 and a photosensitive layer on the support, wherein a surface layer of the electrophotographic photosensitive member contains particles 201, the photosensitive layer has a charge generating layer 204 and a charge transporting layer 203 on the charge generating layer, and the electrophotographic photosensitive member further includes a protective layer 202 on the photosensitive layer, the protective layer being a surface layer (fig. 2).

Layer constitution 3: an electrophotographic photosensitive member includes a support 304 and a photosensitive layer on the support, wherein a surface layer of the electrophotographic photosensitive member contains particles 301, the photosensitive layer is a single-layer photosensitive layer 303, and the electrophotographic photosensitive member further includes a protective layer 302 on the photosensitive layer, the protective layer being a surface layer (fig. 3).

In order to achieve both high transferability and high quality of a halftone image, layer constitution 1 or layer constitution 2 is preferable from the viewpoint of easy control of the arrangement of particles in the surface layer, and layer constitution 1 is more preferable.

Hereinafter, each layer will be described.

< support body >

The electrophotographic photosensitive member according to the present invention includes a support. In the present invention, the support is preferably a conductive support having conductivity. Examples of the shape of the support include cylindrical, ribbon, and sheet. Of these, a cylindrical support is preferable. The surface of the support may be subjected to electrochemical treatments such as anodic oxidation, sand blasting and cutting.

The material of the support is preferably metal, resin, glass, or the like.

Examples of metals include aluminum, iron, nickel, copper, gold, stainless steel, and alloys thereof. Among these, aluminum supports made of aluminum are preferred.

The resin or glass may be mixed with or coated with a conductive material or the like to impart conductivity.

< photosensitive layer >

The photosensitive layers of the electrophotographic photosensitive member are mainly divided into (1) a laminated photosensitive layer and (2) a single-layer photosensitive layer. (1) The laminated photosensitive layer has a charge generation layer containing a charge generation substance and a charge transport layer containing a charge transport substance. (2) The single-layer photosensitive layer has a photosensitive layer containing both a charge generating substance and a charge transporting substance.

(1) Laminated photosensitive layer

The laminated photosensitive layer has a charge generation layer and a charge transport layer.

(1-1) Charge generation layer

The charge generating layer preferably contains a charge generating substance and a resin.

Examples of the charge generating substance include azo pigments, perylene pigments, polycyclic quinone pigments, indigo pigments, and phthalocyanine pigments. Among them, azo pigments and phthalocyanine pigments are preferable. Among such phthalocyanine pigments, oxytitanium phthalocyanine pigments and chlorogallium phthalocyanine pigments, and hydroxygallium phthalocyanine pigments are preferable.

The content of the charge generating substance in the charge generating layer is preferably 40% by mass or more and 85% by mass or less, more preferably 60% by mass or more and 80% by mass or less, based on the total mass of the charge generating layer.

Examples of the resin include polyester resins, polycarbonate resins, polyvinyl acetal resins, polyvinyl butyral resins, acrylic resins, silicone resins, epoxy resins, melamine resins, polyurethane resins, phenolic resins, polyvinyl alcohol resins, cellulose resins, polystyrene resins, polyvinyl acetate resins, and polyvinyl chloride resins. Among them, polyvinyl butyral resins are more preferable.

The charge generating layer may further contain additives such as antioxidants and ultraviolet absorbers. Specific examples thereof include hindered phenol compounds, hindered amine compounds, sulfur compounds, phosphorus compounds, and benzophenone compounds.

The average film thickness of the charge generation layer is preferably 0.1 μm or more and 1 μm or less, and more preferably 0.15 μm or more and 0.4 μm or less.

The charge generation layer can be formed by preparing a coating liquid for a charge generation layer containing the respective materials and a solvent described above to form a coating film of the coating liquid and drying the coating film. Examples of the solvent used for the coating liquid include alcohol-based solvents, sulfoxide-based solvents, ketone-based solvents, ether-based solvents, ester-based solvents, and aromatic hydrocarbon-based solvents.

(1-2) Charge transport layer

The charge transport layer preferably contains a charge transport material and a binder resin.

Examples of the charge transporting substance include polycyclic aromatic compounds, heterocyclic compounds, hydrazone compounds, styrene-based compounds, enamine compounds, benzidine compounds, triarylamine compounds, resins having groups derived from each of these substances. Among them, triarylamine compounds and benzidine compounds are preferable, and compounds having the following structures are suitably used.

[ chemical formula 1]

(in formula (1), R ¹ To R ¹⁰ Each independently represents a hydrogen atom or a methyl group. )

Examples of the structure represented by formula (1) are shown in formulas (1-1) to (1-10). Among them, the structures represented by the respective formulae (1-1) to (1-6) are more preferable.

[ chemical formula 2]

As the binder resin, thermoplastic resins are used, and examples thereof include polyester resins, polycarbonate resins, acrylic resins, and polystyrene resins. Among them, polycarbonate resins and polyester resins are preferable. The polyester resin is particularly preferably a polyacrylate resin.

The content of the charge transport substance in the charge transport layer is preferably 25 mass% or more and 70 mass% or less, more preferably 30 mass% or more and 55 mass% or less, based on the total mass of the charge transport layer.

The content ratio (mass ratio) of the charge transporting substance to the binder resin is preferably 4/10 to 20/10, more preferably 5/10 to 12/10.

In addition, the charge transport layer may contain additives such as antioxidants, ultraviolet absorbers, plasticizers, leveling agents, slip imparting agents, and abrasion resistance improving agents. Specific examples thereof include hindered phenol compounds, hindered amine compounds, sulfur compounds, phosphorus compounds, benzophenone compounds, silicone modified resins, silicone oils, fluororesin particles, polystyrene resin particles, polyethylene resin particles, silica particles, alumina particles, and boron nitride particles.

The average film thickness of the charge transport layer is preferably 5 μm or more and 50 μm or less, more preferably 8 μm or more and 40 μm or less, and particularly preferably 10 μm or more and 30 μm or less.

The charge transport layer can be formed by preparing a coating liquid for a charge transport layer containing the respective materials and a solvent described above to form a coating film of the coating liquid and drying the coating film. Examples of the solvent used for the coating liquid include alcohol-based solvents, ketone-based solvents, ether-based solvents, ester-based solvents, and aromatic hydrocarbon-based solvents. Among these solvents, an ether solvent or an aromatic hydrocarbon solvent is preferable.

In case the charge transport layer is a surface layer, the particles according to the invention are comprised in the surface of the charge transport layer.

(2) Single-layer photosensitive layer

The single-layer photosensitive layer can be formed by preparing a coating liquid for a photosensitive layer containing a charge generating substance, a charge transporting substance, a binder resin, and a solvent to form a coating film of the coating liquid and drying the coating film. The same materials as those in the example of the material in "(1) stacked photosensitive layer" are used as the charge generating substance, the charge transporting substance, and the resin.

< protective layer >

In the present invention, a protective layer may be provided on the photosensitive layer. Durability can be improved by providing a protective layer.

The protective layer preferably comprises conductive particles and/or a charge transporting substance and a binder resin.

The conductive particles include metal oxide particles such as titanium oxide particles, zinc oxide particles, tin oxide particles, and indium oxide particles. Examples of the charge transporting substance include polycyclic aromatic compounds, heterocyclic compounds, hydrazone compounds, styrene-based compounds, enamine compounds, benzidine compounds, triarylamine compounds, resins having groups derived from each of these substances. Among them, triarylamine compounds and benzidine compounds are preferable.

Examples of the binder resin include polyester resins, acrylic resins, phenoxy resins, polycarbonate resins, polystyrene resins, phenolic resins, melamine resins, and epoxy resins. Among them, polycarbonate resins, polyester resins and acrylic resins are preferable. Further, the protective layer may be formed into a cured film by polymerizing a composition including a monomer having a polymerizable functional group. In this case, examples of the reaction include thermal polymerization, photopolymerization, and radiation polymerization. Examples of the polymerizable functional group of the monomer having a polymerizable functional group include an acryl group and a methacryl group. As the monomer having a polymerizable functional group, a material having a charge transporting ability can also be used.

The compound having a polymerizable functional group may have a charge transporting structure and a chain polymerizable functional group. In terms of charge transport, the charge transport structure is preferably a triarylamine structure. The chain-polymerizable functional group is preferably an acryl group or a methacryl group. The number of polymerizable functional groups may be one or more. The case of forming a cured film by introducing a compound having a plurality of polymerizable functional groups and a compound having one polymerizable functional group among these compounds is particularly preferable because distortion caused by polymerization of a plurality of polymerizable functional groups is easily eliminated.

Examples of the compound having one polymerizable functional group are shown in formulas (2-1) to (2-6).

[ chemical formula 3]

Examples of the compound having a plurality of polymerizable functional groups are shown in formulas (3-1) to (3-7).

[ chemical formula 4]

The protective layer may further contain additives such as antioxidants, ultraviolet absorbers, plasticizers, leveling agents, slip imparting agents, and abrasion resistance improving agents. Specific examples thereof include hindered phenol compounds, hindered amine compounds, sulfur compounds, phosphorus compounds, benzophenone compounds, silicone modified resins, silicone oils, fluororesin particles, polystyrene resin particles, polyethylene resin particles, silica particles, alumina particles, and boron nitride particles.

The protective layer may be formed by preparing a coating liquid for protective layer containing each of the above-described materials and a solvent to form a coating film of the coating liquid and drying and/or curing the coating film. Examples of the solvent used for the coating liquid include alcohol-based solvents, ketone-based solvents, ether-based solvents, sulfoxide-based solvents, ester-based solvents, and aromatic hydrocarbon-based solvents.

In case the protective layer is a surface layer, the particles according to the invention are contained in the surface of the protective layer.

Furthermore, the proportion of the volume of the particles to the total volume of the non-protective layer is preferably 20 to 80% by volume. More preferably, the proportion is 25 to 75% by volume, even more preferably 35 to 70% by volume.

< conductive layer >

The electrophotographic photosensitive member according to the present invention may be provided with a conductive layer on a support. This arrangement of the conductive layer can mask defects and irregularities in the surface of the support and control the reflection of light on the surface of the support. The conductive layer preferably contains conductive particles and a resin. Examples of the material of the conductive particles include metal oxides, metals, and carbon black.

Examples of the metal oxide include zinc oxide, aluminum oxide, indium oxide, silicon oxide, zirconium oxide, tin oxide, titanium oxide, magnesium oxide, antimony oxide, and bismuth oxide. Examples of metals include aluminum, nickel, iron, nichrome, copper, zinc, and silver.

Among them, a metal oxide is preferably used as the conductive particles, and particularly, titanium oxide, tin oxide, and zinc oxide are more preferably used.

When a metal oxide is used as the conductive particles, the surface of the metal oxide may be treated with a silane coupling agent or the like, or the metal oxide may be doped with an element such as phosphorus and aluminum, or an oxide thereof.

Further, each conductive particle may be a layered structure including a core particle and a coating layer covering the core particle. Examples of core particles include titanium oxide, barium sulfate, and zinc oxide. The coating layer includes a metal oxide, such as tin oxide.

When a metal oxide is used as the conductive particles, the volume average particle diameter is preferably 1nm or more and 500nm or less, more preferably 3nm or more and 400nm or less.

Examples of the resin include polyester resins, polycarbonate resins, polyvinyl acetal resins, acrylic resins, silicone resins, epoxy resins, melamine resins, polyurethane resins, phenolic resins, and alkyd resins.

The conductive layer may further contain a masking agent such as silicone oil, resin particles, or titanium oxide.

The average film thickness of the conductive layer is preferably 1 μm or more and 50 μm or less, and particularly preferably 3 μm or more and 40 μm or less. The conductive layer can be formed by preparing a coating liquid for a conductive layer containing the respective materials and a solvent described above to form a coating film of the coating liquid and drying the coating film. Examples of the solvent used for the coating liquid include alcohol-based solvents, sulfoxide-based solvents, ketone-based solvents, ether-based solvents, ester-based solvents, and aromatic hydrocarbon-based solvents. The dispersion method of dispersing the conductive particles in the coating liquid for the conductive layer includes a method using a paint stirrer, a sand mill, a ball mill, and a liquid impact type high-speed disperser.

< primer layer >

The electrophotographic photosensitive member according to the present invention may be provided with an undercoat layer on the support or the conductive layer. This arrangement of the undercoat layer can improve the adhesion function between the layers, thereby imparting a charge injection suppressing function.

The primer layer preferably comprises a resin. Further, the primer layer can be formed into a cured film by polymerizing a composition containing a monomer having a polymerizable functional group.

Examples of the resin include polyester resins, polycarbonate resins, polyvinyl acetal resins, acrylic resins, epoxy resins, melamine resins, polyurethane resins, phenol resins, polyvinyl phenol resins, alkyd resins, polyvinyl alcohol resins, polyethylene oxide resins, polypropylene oxide resins, polyamide acid resins, polyimide resins, polyamideimide resins, and cellulose resins.

Examples of the polymerizable functional group of the monomer having a polymerizable functional group include an isocyanate group, a blocked isocyanate group, a hydroxymethyl group, an alkylated hydroxymethyl group, an epoxy group, a metal alkoxide group, a hydroxyl group, an amino group, a carboxyl group, a thiol group, a carboxylic acid anhydride group, and a carbon-carbon double bond group.

In order to improve the electrical properties, the undercoat layer may further contain an electron transporting substance, a metal oxide, a metal, and a conductive polymer. Among them, electron transporting substances and metal oxides can be preferably used.

Examples of the electron transporting substance include quinone compounds, imide compounds, benzimidazole compounds, cyclopentadienyl compounds, fluorenone compounds, xanthone compounds, benzophenone compounds, cyanovinyl compounds, haloaryl compounds, silole compounds, and boron-containing compounds. The undercoat layer may be formed into a cured film by using an electron transporting substance having a polymerizable functional group as the electron transporting substance and copolymerizing with the monomer having a polymerizable functional group.

Examples of the metal oxide include indium tin oxide, indium oxide, titanium oxide, zinc oxide, aluminum oxide, and silicon dioxide. Examples of metals include gold, silver, and aluminum.

The primer layer may also contain additives. The average thickness of the undercoat layer is preferably 0.1 μm or more and 50 μm or less, more preferably 0.2 μm or more and 40 μm or less, and particularly preferably 0.3 μm or more and 30 μm or less.

The undercoat layer may be formed by preparing a coating liquid for the undercoat layer containing each of the above materials and a solvent to form a coating film of the coating liquid, and drying and/or curing the coating film. Examples of the solvent used for the coating liquid include alcohol-based solvents, ketone-based solvents, ether-based solvents, ester-based solvents, and aromatic hydrocarbon-based solvents.

[ Process Cartridge and electrophotographic apparatus ]

The process cartridge integrally supporting at least one step selected from the group consisting of a charging step, a developing step, and a transferring step may be equipped with the above-described electrophotographic photosensitive member. The process cartridge has a feature of being detachably mounted to a main body of the electrophotographic photosensitive apparatus.

Fig. 5 shows an example of schematic configuration of an electrophotographic apparatus having a process cartridge with an electrophotographic photosensitive member according to the present invention.

[ constitution of electrophotographic apparatus ]

The electrophotographic apparatus according to the present embodiment is a so-called tandem type electrophotographic apparatus provided with a plurality of image forming portions "a" to "d". The image is formed with toners of various colors, wherein a first image forming portion "a" forms an image with yellow (Y) toner, a second image forming portion "b" forms an image with magenta (M) toner, a third image forming portion "C" forms an image with cyan (C) toner, and a fourth image forming portion "d" forms an image with black (Bk) toner. The four image forming portions are arranged in a row at constant intervals, and the image forming units are configured with substantially the same number of portions except for the color of the toner. Therefore, the electrophotographic apparatus of the present embodiment will be described below using the first image forming portion "a".

The first image forming portion "a" includes a photosensitive drum 1a as a drum-shaped photosensitive member, a charging roller 2a as a charging member, a developing unit 4a, and a drum cleaning unit 5a.

The photosensitive drum 1a is an image bearing member that bears a toner image, and is rotationally driven at a predetermined peripheral speed (process speed) in the direction of an arrow R1 shown in the figure. The developing unit 4a is a device that stores yellow toner to develop a yellow toner image on the photosensitive drum 1 a. The drum cleaning unit 5a is a unit for collecting toner adhering to the photosensitive drum 1 a. The drum cleaning unit 5a includes a cleaning blade that contacts the photosensitive drum 1a and a toner collection box that stores toner or the like removed from the photosensitive drum 1a by the cleaning blade.

When a control unit (not shown) such as a controller receives an image signal, an image forming operation is started while the photosensitive drum 1a is rotationally driven. During rotation, the photosensitive drum 1a is uniformly charged by the charging roller 2a to have a predetermined voltage (charging voltage) of a predetermined polarity (negative polarity in this embodiment), and is exposed by the exposure unit 3a in accordance with an image signal. Through the above-described operation, an electrostatic latent image corresponding to an image of a yellow component in a desired color image is formed. Subsequently, the electrostatic latent image is developed at the development position by the development unit 4a, and visualized as a yellow toner image on the photosensitive drum 1 a. In this regard, the conventional charging polarity of the toner contained in the developing unit 4a is a negative polarity, and the electrostatic latent image is developed in a reverse manner to the toner charged by the charging roller 2a so as to have the same charging polarity as the photosensitive drum 1 a. However, without being limited to the above, the present invention can be applied to an electrophotographic apparatus that performs positive development of an electrostatic latent image with toner that has been charged to a polarity opposite to the charging polarity of the photosensitive drum 1 a.

The endless and movable intermediate transfer belt 10 has conductivity, forms a primary transfer portion N1a by contacting the photosensitive drum 1a, and rotates at substantially the same peripheral speed as the photosensitive drum 1 a. Further, the intermediate transfer belt 10 is stretched by the opposing roller 13 serving as an opposing member, the driving roller 11 and the tension roller 12 each serving as a tension member, and the metal roller 14a, and is stretched together with the tension roller 12 at a tension of a total pressure of 60N in total. The intermediate transfer belt 10 can be moved by rotatably driving the driving roller 11 in the direction of arrow R2 shown in the figure. Further, the metal roller 14 and the counter roller 13 are each grounded via a zener diode 15 as a constant voltage element.

In the process of passing through the primary transfer portion N1a, the yellow toner image formed on the photosensitive drum 1a is primary-transferred from the photosensitive drum 1a to the intermediate transfer belt 10. The primary transfer residual toner remaining on the surface of the photosensitive drum 1a is cleaned and removed by the drum cleaning unit 5a, and then used for an image forming process in a charging step and thereafter.

During primary transfer, an electric current is supplied to the conductive intermediate transfer belt 10 from a secondary transfer roller 20 serving as a secondary transfer member in contact with the outer peripheral surface of the intermediate transfer belt 10. When the current supplied from the secondary transfer roller 20 flows in the circumferential direction of the intermediate transfer belt 10, the toner image is primary-transferred from the photosensitive drum 1a to the intermediate transfer belt 10. Thus, a voltage having a predetermined polarity (positive polarity in the present embodiment) opposite to the normal charging polarity of the toner is applied from the transfer power source 21 to the secondary transfer roller 20.

Hereinafter, in the same manner, a toner image formed of the second color magenta, a toner image formed of the third color cyan, and a toner image formed of the fourth color black are formed and transferred onto the intermediate transfer belt 10 in a sequential manner so as to overlap each other. Through the above-described operation, a toner image including four colors corresponding to a desired color image is formed on the intermediate transfer belt 10. Thereafter, in the process of passing through the secondary transfer portion N2 formed by the secondary transfer roller 20 and the intermediate transfer belt 10 being in contact with each other, the four-color toner image carried on the intermediate transfer belt 10 is once and secondarily transferred onto the surface of the transfer material P such as paper or OHP sheet fed from the paper feeding unit 50. Subsequently, the transfer material P on which the four-color toner image has been secondarily transferred is heated and compressed in the fixing unit 30, so that the four-color toners are melted and mixed and fixed to the transfer material P. The toner remaining on the intermediate transfer belt 10 after the secondary transfer is cleaned and removed by a belt cleaning unit 16, the belt cleaning unit 16 being disposed so as to oppose the opposing roller 13 via the intermediate transfer belt 10 interposed between the belt cleaning unit 16 and the opposing roller 13. Further, a current path is provided which is not connected to the secondary transfer roller 20 but electrically connects the transfer power supply 21 and the metal roller 14 to each other through a constant current diode 22 serving as a constant current element. When a voltage is applied from the transfer power supply 21 to the secondary transfer roller 20, a pinch-off current Id flows through the constant current diode 22 in addition to the current It2 flowing to the secondary transfer portion N2.

The electrophotographic photosensitive member according to the present invention can be used in laser beam printers, LED printers, copying machines, and the like.

[ method of evaluating electrophotographic photosensitive Member ]

The evaluation method in the present invention will be described.

< method for measuring the exposed volume and the exposed number of particles in the surface layer of the photosensitive Member >

The electrophotographic photosensitive member according to the present invention was cut out at three points 50mm from each end portion and the center portion in the length direction, and at four points every 90 degrees in the circumferential direction, that is, at 12 points in total, to obtain a square of 5 mm. The photosensitive layer of the sample was plated with platinum by evaporation for 30 seconds.

In FIB-SEM (NVision 40, manufactured by Carl Zeiss co., ltd.) the following cuts were made for each sample.

Beam type: gallium ion beam

Acceleration voltage: 1kV

Size: 3 μm long, 3 μm wide and 3 μm deep

Length of the processing steps: 10nm of

The number of steps: 300

Further, for each step, SEM observation was performed at an acceleration voltage of 5kV, a focal length WD of 5mm, and a field of view at 30,000 magnification.

All images captured by FIB-SEM are converted to three-dimensional images by interface in image processing and analysis software ("exfectvr2.1", manufactured by Nihon Visual Science, inc.). The number of particles exposed from the surface layer of the photosensitive member is measured from the three-dimensional image, and the ratio of the number of exposed particles to the total number of particles contained in the surface layer is calculated.

Further, the resulting three-dimensional image is compared with an image of the particle exposed from the surface layer cut by FIB-SEM, and a cross-sectional image of the particle cut with its centroid is brought into an image processing and analyzing device ("LUZEX AP", manufactured by NIRECO CORPORATION) through an interface to binarize the particle in the cross-sectional image. As shown in the conceptual view of fig. 6, from the cross section of the particles exposed from the surface layer of the photosensitive member, the particles in the surface layer approximate spherical particles of a virtual true sphere whose particle radius R is 1/2 of the sum of the major axis L and the minor axis L of the particles. The centroid of the cross-section of the particle emerging from the surface layer coincides with the centroid of the spherical particle of the virtual true sphere. For the particles exposed from the surface layer of the photosensitive member, calculation was performed by approximating the surface layer 602 in which the resin portion was exposed to a smooth surface with little fluctuation. The depth of the portion where the particles contained in the surface layer of the photosensitive member according to the present invention are buried from the surface layer 602 of the resin portion is defined as h.

Further, when the bottom surface of the portion exposed from the surface layer 602 of the resin portion is viewed from above, the virtual true sphere approximates a circle having the radius C of the particle (conceptual view is shown in fig. 6).

The volume V of the exposed portion of the particles is calculated from the following formula (B):

V＝4πR ³ /3-πh(3C ² +h ² ) /6. (B)

The volume of the exposed portion of the particles in the three-dimensional image is measured, the sum of the volumes of the exposed portions of the particles partially exposed from the surface layer is calculated, and the sum is divided by the total volume of the particles contained in the surface layer to calculate the volume ratio of the exposed portions of the particles partially exposed from the surface layer.

< method for measuring volume average particle diameter of particles of the present invention >

Volume average particle size was measured using a ZETASIZER NANO-ZS (Malvern Panalytical Ltd.). The apparatus measures particle size using dynamic light scattering. The sample to be measured was first prepared by dilution to a solid-to-liquid ratio of 0.10 mass% (±0.02 mass%), collected in a quartz cell, and placed in a measuring section. When the sample is inorganic fine particles, water or a methyl ethyl ketone/methanol mixed solvent is used as a dispersion medium, and when the sample is resin particles or an external additive for toner, water is used as a dispersion medium. Prior to measurement, the refractive index of the sample and the refractive index, viscosity and temperature of the dispersion solvent were input as measurement conditions into Zetasizer Software 6.30.30 control software. Dn is taken as the number average particle size.

The refractive index of the particles was taken from the handbook of chemistry, second volume, version 4 revision base (vol.ii of the Chemical Handbook, basic Edition of the Revised th edition) (ed.chemical Society of Japan, maruzen Publishing co., ltd), "refractive index of solids (Refractive indices of solids)", on page 517. As for the refractive index of the resin particles, the refractive index stored in the control software is used as the refractive index of the resin used in the resin particles. However, if the refractive index is not stored in the control software, the values described in the polymer database of the national institute of materials science (National Institute for Materials Science) are used. The refractive index of the external additive for toner is calculated by weighted-averaging the refractive index of the inorganic fine particles and the refractive index of the resin used in the resin particles. The values stored in the control software are selected for the refractive index, viscosity and temperature of the dispersing solvent. In the case of a mixed solvent, the values of the mixed dispersion medium are weighted and averaged.

< method for measuring coating ratio and coefficient of variation of particles in surface layer of photosensitive Member >

In the electrophotographic photosensitive member according to the present invention, when the surface layer is observed from above, S1/(s1+s2) can be calculated as follows, where S1 is the total area of the exposed portions of the particles.

For particles in the surface layer, a photographic image of the surface layer of the photosensitive member photographed at a magnification of 30,000 times using a Scanning Electron Microscope (SEM) ("S-4800", manufactured by JEOL, ltd.) was captured by a scanner to binarize the particles in the photographic image using an image processing and analyzing apparatus ("LUZEX AP", manufactured by NIRECO CORPORATION). The coverage S1/(s1+s2) (%) was calculated, where S1 is the area of the exposed portion of the particles in the photosensitive member in one field of view, and S2 is the total area of the particles except for the exposed portion. The above-described coating ratio was calculated for a total of 10 fields of view, and the average value of the obtained coating ratios was defined as the coating ratio of the particles in the surface layer of the photosensitive member.

< method for measuring circularity of particles exposed in surface layer of photosensitive Member >

For particles in the surface layer, a photographic image of the surface layer of the photosensitive member photographed at a magnification of 30,000 times using a Scanning Electron Microscope (SEM) ("S-4800", manufactured by JEOL, ltd.) was captured by a scanner, and image analysis was performed using image processing software (ImageJ (available from https:// ImageJ. The electrophotographic photosensitive member according to the present invention was cut out at three points 50mm from each end portion and the center portion in the length direction, and at four points each of 90 degrees in the circumferential direction, that is, at 12 points in total, to obtain a square of 5 mm. Taking the central portion of the sample as one field of view, calculating the circularities of all particles in one field of view, and defining the average value of the obtained circularities as the circularities of the particles exposed in the surface layer of the photosensitive member.

< method for measuring the relief of particles exposed in the surface layer of a photosensitive Member >

Meanwhile, the form factor of the exposed particles in the surface layer of the photosensitive member is obtained by randomly sampling 100 particle images magnified 30,000 times using, for example, FE-SEM (S-4800) manufactured by Hitachi, ltd. Through the interface, the image information is brought into an image processing and analysis device ("LUZEX AP", manufactured by NIRECO CORPORATION), binarized and analyzed. The value calculated by the following formula C is defined as the shape factor SF-2:

(SF-2)＝(PER)2/(AREA)×1/(4π)×100...(C)

(in the formula, PER represents the circumference of the particle, and AREA represents the projected AREA of the particle.)

The shape factor SF-2 indicates the degree of fine irregularities on the particle surface.

If SF-2 exceeds 135, the transfer efficiency of the toner image from the photosensitive member to the intermediate transfer member and the transfer material is lowered, and transfer leakage of the character and line images is undesirably caused.

< method for measuring Young's modulus of particles exposed from surface layer of photosensitive Member >

As the evaluation apparatus, an SPM probe station (manufactured by Hitachi High-Tech Science Corporation, "NanoNavRef") equipped with a scanning probe microscope (manufactured by Hitachi High-Tech Science Corporation, "S-image") having a built-in heater was used. Prior to measurement, the evaluation apparatus was calibrated using polymethyl methacrylate (PMMA) particles as a reference substance under conditions allowing a range of 2.920 ±0.119Gpa (young's modulus). The Young's modulus of PMMA measured by the calibrated evaluation device was 3.01GPa.

Particles in the surface layer of the electrophotographic photosensitive member were measured with SPM, and the average value of 10 measurement results of one particle was defined as the young's modulus of one particle. Further, the average value of young's modulus of 10 particles was taken as young's modulus of the exposed particles in the surface layer of the photosensitive member of the present invention.

Examples (example)

Hereinafter, the present invention will be described in more detail with examples and comparative examples. The present invention is not limited at all by the following examples, as long as it does not deviate from the gist thereof. Note that the term "part" or "parts" is based on mass unless otherwise specified in the examples below. The film thickness of each layer of the electrophotographic photosensitive member in examples and comparative examples was measured with an eddy current film thickness meter (manufactured by fischer, fischer Instruments k.k.) or based on specific gravity converted from mass per unit area.

Table 1 shows the types, manufacturers, number average particle diameters, volume average particle diameters, and (volume average particle diameter)/(number average particle diameter) of particles contained in the surface layer of the electrophotographic photosensitive member according to the present invention.

TABLE 1

(production of surface-treated particles 1)

The following materials were added and dispersed at room temperature using a US homogenizer for 30 minutes:

Methanol: 10 parts by mass

Particle 1 (listed in table 1): 5 parts by mass.

Next, 0.25 parts by mass of n-propyltrimethoxysilane (manufactured by Shin-Etsu Chemical co., ltd.) and 10 parts by mass of toluene as reactive surface treating agents were added, followed by stirring at room temperature for 60 minutes. After the solvent was removed by an evaporator, the resultant was heated at 140 ℃ for 60 minutes to produce surface-treated particles 1 which had been surface-treated with a reactive surface-treating agent. The particles had a volume average particle diameter of 136nm and a number average particle diameter of 124nm.

< production example of electrophotographic photosensitive member 1 >

(preparation of support)

An aluminum cylinder (JIS-A3003, aluminum alloy) having a diameter of 20mm and a length of 257.5mm was used as the support (conductive support).

(preparation example of coating liquid 1 for conductive layer)

The following materials were dispersed to obtain 1L of an aqueous suspension:

anatase titanium dioxide: 100 parts by mass (average primary particle diameter: 150nm, niobium content: 0.20% by weight)

Pure water: 1000 parts by mass.

The aqueous suspension was heated to 60 ℃.

A titanium niobate solution containing 3 parts by mass of niobium pentachloride (NbCl) dissolved in 100mL of 11.4mol/L hydrochloric acid ₅ ) A mixture of 600mL of a titanium sulfate solution containing 33.7 parts by mass of Ti, and 10.7mol/L sodium hydroxide solution were simultaneously added dropwise to the suspension over 3 hours so that the pH of the suspension reached 2 to 3. After the completion of the dropwise addition, the suspension was filtered, washed and dried at 110℃for 8 hours.

The obtained dried product was heat-treated in an atmosphere at 800 ℃ for 1 hour, thereby obtaining a powder comprising a core material comprising titanium oxide and a coating layer comprising titanium oxide doped with niobium metal oxide particles 1.

Next, the following materials were mixed:

phenolic resin

(trade name: plyophen J-325, manufactured by DIC Corporation, resin solid content: 60%, density after curing: 1.3 g/cm) ² ): 50 parts by mass

1-methoxy-2-propanol: 35 parts by mass

Metal oxide particles 1: 75 parts by mass

Glass beads (average particle size: 1.0 mm): 120 parts by mass.

The mixture was charged into a vertical sand mill, and subjected to dispersion treatment at a dispersion temperature of 23.+ -. 3 ℃ and a rotational speed of 1,500rpm (peripheral speed: 5.5 m/s) for 4 hours, thereby obtaining a metal oxide particle dispersion liquid 1. Glass beads were removed from the metal oxide particle dispersion 1 with a screen, and the following materials were added thereto, followed by stirring:

silicone oil (trade name: SH28 PAINT ADDITIVE, manufactured by Dow Corning Toray co., ltd.): 0.01 part by mass.

Silicone resin particles (trade name: TOSPEARL 120, manufactured by Momentive Performance Materials, inc., average particle size: 2 μm, density: 1.3 g/cm) ² ): 10 parts by mass.

The resultant was filtered under pressure using a PTFE filter (trade name: PF060, manufactured by Advantec Toyo Kaisha, ltd.) to thereby prepare a coating liquid 1 for a conductive layer.

(example of producing conductive layer 1)

The conductive layer was coated on the support with the coating liquid 1 by dip coating and heated at 140 ℃ for one hour, thereby forming the conductive layer 1 having a film thickness of 20 μm.

(preparation example of coating liquid 1 for undercoat layer)

The following materials were mixed and then stirred for 8 hours:

rutile type titanium oxide particles (average primary particle diameter: 50nm, manufactured by Tayca Corporation): 100 parts by mass

Phenolic resin (trade name: plyophen J-325, manufactured by DIC Corporation, resin solid content: 60 mass%): 132 parts by mass

Toluene: 500 parts by mass

Vinyltrimethoxysilane (trade name: KBM-1003, manufactured by Shin-Etsu Chemical Co., ltd.): 5 parts by mass

Glass beads (diameter: 0.8 mm): 450 parts by mass.

Thereafter, toluene was distilled off under reduced pressure, and the resultant was dried at 120℃for 3 hours, thereby obtaining rutile titanium oxide particles 1 which had been surface-treated with vinyltrimethoxysilane.

The following materials were mixed:

surface-treated rutile titanium particles: 18 parts by mass

N-methoxymethylated nylon (trade name: tolesin EF-30T, manufactured by Nagase ChemteX Corporation): 4.5 parts by mass

Copolymer nylon resin (trade name: amilan CM8000, manufactured by Toray Industries, inc.): 1.5 parts by mass

Methanol: 90 parts by mass

1-butanol: 60 parts by mass

Acetone: 15 parts by mass

Glass beads (average particle size: 1.0 mm): 120 parts by mass.

The mixture was subjected to dispersion treatment with a vertical sand mill for 5 hours to prepare a coating liquid 1 for an undercoat layer.

(production example of undercoat layer 1)

The coating liquid 1 for an undercoat layer was coated onto the conductive layer 1 by dip coating, and heated at 170 ℃ for 30 minutes, thereby forming the undercoat layer 1 having a film thickness of 1.0 μm.

(example of producing the Charge generating layer 1)

The following materials were dispersed in a sanding apparatus for 6 hours:

hydroxygallium phthalocyanine (peaks at positions 7.5 ° and 28.4 ° in a graph obtained by cukα characteristic X-ray diffraction): 10 parts by mass

Polyvinyl butyral resin (trade name: S-LEC BX-1, manufactured by Sekisui Chemical co., ltd.): 5 parts by mass

Cyclohexanone: 200 parts by mass

Glass beads: 200 parts by mass.

Next, 150 parts by mass of cyclohexanone and 350 parts by mass of ethyl acetate were further added thereto to obtain a coating liquid 1 for a charge generation layer. The obtained charge generation layer coating liquid 1 was coated onto the undercoat layer 1 by dip coating, and dried at 95 ℃ for 10 minutes, thereby forming the charge generation layer 1 having a film thickness of 0.20 μm.

(example of manufacturing charge transport layer 1)

Next, the following materials were prepared:

a charge transporting substance (hole transporting substance) represented by the structural formula (1-1): 5 parts by mass

A charge transporting substance (hole transporting substance) represented by structural formula (1-3): 5 parts by mass

Polycarbonate (trade name: iupilon Z400, manufactured by Mitsubishi Engineering-Plastics Corporation): 10 parts by mass

A polycarbonate resin having copolymer units of the following structural formulae (C-1) and (C-2): 0.02 part (x/y=0.95/0.05, viscosity average molecular weight=20,000)

These were dissolved in a mixed solvent of 60 parts by mass of toluene/3 parts by mass of methyl benzoate/15 parts by mass of tetrahydrofuran to prepare a coating liquid 1 for a charge transport layer. The charge transport layer coating liquid 1 was coated onto the charge generation layer 1 by dip coating to form a coating film, and the coating film was dried at a drying temperature of 40 ℃ for 5 minutes, thereby forming the charge transport layer 1 having a film thickness of 15 μm.

[ chemical formula 5]

[ chemical formula 6]

(preparation example 1 of particle-containing surface layer)

Next, the following materials were prepared:

particle 1:1.2 parts by mass (listed in Table 1)

Siloxane-modified acrylic compound (trade name: SYMAC US270, toagosei co., manufactured by ltd.): 0.1 part by mass

Cyclohexane: 30 parts by mass

1-propanol: 70 parts by mass

The materials listed above were mixed and stirred to prepare a coating liquid 1 for a surface layer.

The surface layer was coated with the coating liquid onto the charge transport layer 1 by dip coating to form a coating film, and the resulting coating film was dried at 100 ℃ for 20 minutes to obtain the electrophotographic photosensitive member 1. On the electrophotographic photosensitive member 1, the following data were obtained by measurement: the film thickness [ μm ] of the charge transporting layer, the volume average particle diameter [ nm ] of the particles contained in the surface layer, the number ratio [ number% ] of the particles exposed from the surface layer, the volume ratio [ number% ] of the particles exposed from the surface layer, the coating ratio S1/(s1+s2) of the particles exposed from the surface layer and its coefficient of variation, the average circularity and SF-2 of the shape of the exposed portion of the particles exposed from the surface layer, the young' S modulus [ GPa ] of the surface of the particles exposed from the surface layer, the volume average particle diameter/number average particle diameter of the particles, the ash content [ mass% ] of insoluble components relative to methyl ethyl ketone in the surface layer during sintering, and the content ratio [ volume% ] of the particles contained in the surface layer. The results are shown in table 3.

< production examples 2 to 36 of electrophotographic photosensitive Member >

Electrophotographic photosensitive members 2 to 36 were each produced in the same manner as in the production example of the electrophotographic photosensitive member 1 except for changing the temperature at which the coating liquid 1 for a charge transporting layer in the production example of the charge transporting layer 1 was coated onto the charge generating layer 1 by dip coating to form a coating film and dried, the types and the addition amounts of the particles contained in the surface layer, and the addition amounts of cyclohexane and 1-propanol as shown in table 2. Physical properties of the electrophotographic photosensitive members 2 to 36 were each measured. The results are shown in table 3.

TABLE 2

TABLE 3

TABLE 3 Table 3

< production example of electrophotographic photosensitive member 37 >

An electrophotographic photosensitive member was produced in the same manner as in the production example of the electrophotographic photosensitive member 1 up to the production example of the charge transporting layer 1 except that the coating liquid 37 for a charge transporting layer was coated onto the charge generating layer 37 by dip coating to form a coating film, and the coating film was dried at a drying temperature of 120 ℃ for 5 minutes to produce the charge transporting layer 37 having a film thickness of 15 μm.

Production example 2 of particle-containing surface layer

Next, the following materials were prepared:

particle 1:1.2 parts by mass (listed in Table 1)

A charge transporting substance (hole transporting substance) represented by the structural formula (2-1): 0.1 part by mass

A charge transporting substance (hole transporting substance) represented by the structural formula (3-1): 0.2 part by mass

Cyclohexane: 30 parts by mass

1-propanol: 70 parts by mass

The materials listed above were mixed and stirred to prepare the coating liquid 2 for a surface layer.

The coating liquid 2 for a surface layer was coated onto the charge transport layer 1 by dip coating to form a coating film, and the resulting coating film was dried at 40 ℃ for 5 minutes.

Thereafter, the coating film was irradiated with an electron beam for 1.6 seconds while the support (irradiated body) was rotated at a speed of 300rpm under an acceleration voltage of 70kV and a beam current of 5.0mA under a nitrogen atmosphere. The dose at the outermost surface layer position was 15kGy. After that, the first heating was performed by raising the temperature of the coating film from 25 ℃ to 100 ℃ in 20 seconds under a nitrogen atmosphere to form a surface layer having a film thickness of 1.0 μm. The oxygen concentration during the period from the irradiation of the electron beam to the subsequent heat treatment is 10ppm or less. Next, the coating film was naturally cooled in air until its temperature became 25 ℃, and a second heat treatment was performed for 20 minutes under the condition that the coating film temperature became 100 ℃. Thereby, the electrophotographic photosensitive member 37 is produced. By measurement, the following data are obtained for the electrophotographic photosensitive member 37: the film thickness [ μm ] of the charge transporting layer, the film thickness [ μm ] of the surface layer, the volume average particle diameter [ nm ] of particles contained in the surface layer, the number ratio [ number% ] of particles exposed from the surface layer, the volume ratio [ number% ] of particles exposed from the surface layer, the coating ratio S1/(s1+s2) of particles exposed from the surface layer, the average circularity of the shape of the exposed portion of particles exposed from the surface layer, the young' S modulus [ GPa ] of the surface of particles exposed from the surface layer, the volume average particle diameter/number average particle diameter of particles, the ash content [ mass% ] of insoluble components relative to methyl ethyl ketone in the surface layer during sintering, and the content ratio [ volume% ] of particles contained in the surface layer. The results are shown in Table 5.

< production examples 38 to 72 of electrophotographic photosensitive Member >

Electrophotographic photosensitive members 38 to 72 were each produced in the same manner as in the production example of the electrophotographic photosensitive member 37 except that the temperature at which the coating liquid 37 for a charge transporting layer in the production example of the charge transporting layer 37 was coated onto the charge generating layer 37 by dip coating to form a coating film and dried was changed as shown in table 4, and in the production example 2 of the surface layer containing particles, the types and the addition amounts of the particles contained in the surface layer, and the addition amounts of cyclohexane and 1-propanol were each changed. Physical properties of the electrophotographic photosensitive members 38 to 72 were each measured. The results are shown in Table 5.

TABLE 4

TABLE 4 Table 4

TABLE 5

Table 5 (subsequent)

Production example of electrophotographic photosensitive member 73

An electrophotographic photosensitive member was produced in the same manner as in production example 1 up to production example 1 of an undercoat layer in the production example of the electrophotographic photosensitive member 1.

[ formation of Single-layer photosensitive layer ]

[ production of photosensitive Member ]

The following compounds were placed in a container:

charge generating agents, oxytitanium phthalocyanine: 2 parts by mass

Hole transporter (HTM-1): 65 parts by mass

Electron transport agent (ETM-1): 33.5 parts by mass

Electron transport agent (ETM-2): 33.5 parts by mass

Resin (formula D below): 138 parts by mass

Solvent (tetrahydrofuran): 400 parts by mass

Thus, the coating liquid 73 for forming a photosensitive layer was obtained. The photosensitive layer forming coating liquid 73 was coated onto a support by dip coating, and heated at 40 ℃ for 5 minutes, thereby forming a single-layer type photosensitive layer 1 having a film thickness of 15 μm.

[ chemical formula 7]

[ chemical formula 8]

[ chemical formula 9]

(preparation example 3 of particle-containing surface layer)

Next, the following materials were prepared:

particle 1:1.2 parts by mass (listed in Table 1)

Siloxane-modified acrylic compound (trade name: SYMAC US270, manufactured by Toagosei co., ltd.): 0.1 part by mass

Cyclohexane: 30 parts by mass

1-propanol: 70 parts by mass

The materials listed above are mixed and stirred to prepare the coating liquid 3 for the surface layer.

The coating liquid 3 for a surface layer was coated onto the single-layer type photosensitive layer 1 by dip coating to form a coating film, and the resulting coating film was dried at 100 ℃ for 20 minutes to obtain an electrophotographic photosensitive member 73. The following data were obtained by measurement: the film thickness [ μm ] of the charge transporting layer, the volume average particle diameter [ nm ] of the particles contained in the surface layer, the number ratio [ number% ] of the particles exposed from the surface layer, the volume ratio [ number% ] of the particles exposed from the surface layer, the coating ratio S1/(s1+s2) of the particles exposed from the surface layer, the average circularity of the shape of the exposed portion of the particles exposed from the surface layer, the young' S modulus [ GPa ] of the surface of the particles exposed from the surface layer, the volume average particle diameter/number average particle diameter of the particles, the ash content [ mass% ] of insoluble components relative to methyl ethyl ketone in the surface layer during sintering, and the content ratio [ volume% ] of the particles contained in the surface layer. The results are shown in Table 5.

< production examples 74 to 88 of electrophotographic photosensitive Member >

Electrophotographic photosensitive members 74 to 88 were each produced in the same manner as in the production example of the electrophotographic photosensitive member 1 except for changing the temperature at which the coating liquid 1 for a charge transporting layer in the production example of the charge transporting layer 1 was coated onto the charge generating layer 1 by dip coating to form a coating film and dried, the type and the addition amount of particles contained in the surface layer, and the addition amount of cyclohexane and 1-propanol as shown in table 6. Physical properties of the electrophotographic photosensitive members 74 to 88 were each measured. The results are shown in Table 7.

TABLE 6

TABLE 7

< production examples 89 to 103 of electrophotographic photosensitive Member >

Electrophotographic photosensitive members 89 to 103 were each produced in the same manner as in the production example of the electrophotographic photosensitive member 37 except that the temperature at which the charge-transporting layer coating liquid 37 was coated onto the charge-generating layer 37 by dip coating to form a coating film and dried, and the type and the addition amount of the particles contained in the surface layer, and the addition amount of cyclohexane and 1-propanol, in production example 2 of the surface layer containing the particles, were changed as shown in table 8. Physical properties of the electrophotographic photosensitive members 89 to 103 were each measured. The results are shown in Table 9.

TABLE 8

TABLE 9

Watch 9 (subsequent)

< production example 104 of electrophotographic photosensitive Member >

An electrophotographic photosensitive member 24 was produced in the same manner as in the production example of the electrophotographic photosensitive member 1 except that the drying temperature and drying time in the production example 1 of the charge transporting layer 1 were changed to 130 ℃ and 20 minutes, respectively. Physical properties of the electrophotographic photosensitive members 104 were each measured. The results are shown in Table 9.

< production example 105 of electrophotographic photosensitive Member >

An electrophotographic photosensitive member 105 was produced in the same manner as in the production example of the electrophotographic photosensitive member 37 except that the particles 1 were not added in (production example 2 of a surface layer containing particles). Physical properties of the electrophotographic photosensitive members 105 were each measured. The results are shown in Table 9.

< production example 106 of electrophotographic photosensitive Member >

An electrophotographic photosensitive member 106 was produced in the same manner as in the production example of the electrophotographic photosensitive member 73 except that the particles 1 were not added in (production example 3 of a surface layer containing particles). Physical properties of the electrophotographic photosensitive members 106 were each measured. The results are shown in Table 9.

< production example 107 of electrophotographic photosensitive Member >

An electrophotographic photosensitive member was produced in the same manner as in the production example of the electrophotographic photosensitive member 37 up to the production example of the charge transporting layer 2.

(production of surface-treated particles 2)

methanol: 10 parts by mass

5 parts by mass of tin oxide/barium sulfate (number average particle diameter: 100 nm).

Next, 0.25 parts by mass of a side chain type silicone surface treatment agent ("KF 9908", manufactured by Shin-Etsu Chemical co., ltd.) having a silicone chain on a side chain of the silicone main chain, 0.25 parts by mass of a reactive surface treatment agent ("KBM-503", manufactured by Shin-Etsu Chemical co., ltd.) and 10 parts by mass of toluene were added, followed by stirring at room temperature for 60 minutes. After the solvent was removed by an evaporator, the resultant was heated at 120 ℃ for 60 minutes to produce surface-treated particles 2 which had been surface-treated with a reactive surface-treating agent. The volume average particle diameter of the particles was 200nm and the number average particle diameter was 110nm.

Then, the following materials were mixed to prepare a coating liquid 107 for a surface layer:

radical polymerizable monomer (trimethylolpropane trimethacrylate): 120 parts by mass

Surface-treated particles 2:100 parts by mass

Polymerization initiator (IRGACURE (registered trademark) 819, manufactured by BASF Japan ltd):

10 parts by mass

2-butanol: 800 parts by mass

Subsequently, the obtained coating liquid 107 for a surface layer was coated onto the charge transport layer 2 by dip coating to form a coating film, and then a metal halide lamp (cumulative light amount: 960mJ/cm ² ) At 16mW/cm ² The coating film was irradiated with ultraviolet rays for 1 minute to form a surface layer having a dry film thickness of 1.0 μm, thereby preparing an electrophotographic photosensitive member 107. Physical properties of the electrophotographic photosensitive members 107 were each measured. The results are shown in Table 9.

< production example 108 of electrophotographic photosensitive Member >

First, 100 parts of monochlorobenzene, 10 parts of spherical polymethylsilsesquioxane particles (trade name: TOSPEARL 145, manufactured by Momentive Performance Materials Japan LLC, previously referred to as Toshiba Silicone co., ltd.) as organic-inorganic hybrid particles having an average particle diameter of 4.5 μm were put into a paint shaker and dispersed for 3 hours, thereby obtaining a coating liquid 108 for a surface layer.

The charge transport layer coating liquid 1 and the surface layer coating liquid 108 in production example 1 of the electrophotographic photosensitive member were mixed with stirring to prepare a charge transport layer coating liquid 108. The charge transport layer coating liquid 108 was coated onto the charge generation layer 1 by dip coating, and the resulting coating film was dried at 120 ℃ for one hour, thereby forming the charge transport layer 108 having a film thickness of 16 μm. Next, the surface of the charge transporting layer 108 was treated with a hydrofluoric acid solution having a concentration of 20 mass%, thereby obtaining an electrophotographic photosensitive member 108 in which the charge transporting layer was a surface layer.

When observed with a Scanning Electron Microscope (SEM), the particles were bonded to the charge transport layer prior to the hydrofluoric acid treatment, whereas after the hydrofluoric acid treatment, the particles were not bonded to the charge transport layer, and there were many gaps between the particles and the inner surfaces of the pores of the charge transport layer 108. Physical properties of the electrophotographic photosensitive members 108 were each measured. The results are shown in Table 9.

< production example of toner particle 1 >

(preparation of aqueous Medium 1)

First, 650.0 parts of ion-exchanged water and 14.0 parts of sodium phosphate (manufactured by Rasa Industries, ltd., 12 hydrate) were placed in a reaction vessel equipped with a stirrer, a thermometer and a return tube, and kept at 65 ℃ for 1.0 hour under a nitrogen purge.

An aqueous solution of 9.2 parts of calcium chloride (2 hydrate) dissolved in 10.0 parts of ion-exchanged water was all placed in a reaction vessel at one time with stirring at 15,000rpm using t.k.homo MIXER (manufactured by PRIMIX Corporation, previously referred to as Tokushu Kika Kogyo co., ltd.) to prepare an aqueous medium containing a dispersion stabilizer. Further, 10 mass% hydrochloric acid was put into an aqueous medium to adjust the pH to 5.0, thereby obtaining an aqueous medium 1.

(preparation of polymerizable monomer composition)

The following materials were placed in a grinder (manufactured by Nippon Coke & Engineering co., ltd., formerly Mitsui Miike Kakoki co., ltd.):

styrene: 60.0 parts of

C.i. pigment blue 15:3: 6.5 parts of

These materials were dispersed with zirconia particles having a diameter of 1.7mm at 220rpm for 5.0 hours, and then the zirconia particles were removed to prepare a colorant dispersion.

On the other hand, the following materials were added to the above colorant dispersion:

styrene: 20.0 parts

N-butyl acrylate: 20.0 parts

Crosslinking agent (divinylbenzene): 0.3 part

Saturated polyester resin: 5.0 parts of

( Polycondensation product of propylene oxide modified bisphenol a (2 mol adduct) with terephthalic acid (molar ratio 10:12), glass transition temperature (Tg): 68 ℃, weight average molecular weight (Mw): 10,000, molecular weight distribution (Mw/Mn): 5.12 )

Fischer-Tropsch wax (melting point 78 ℃ C.). 7.0 parts

The mixture was heated to 65 ℃ and then uniformly dissolved and dispersed at 500rpm by using t.k.homo MIXER (manufactured by PRIMIX Corporation, previously referred to as Tokushu Kika Kogyo co., ltd.) to prepare a polymerizable monomer composition.

(granulating step)

After the temperature of the aqueous medium 1 was adjusted to 70 ℃, the polymerizable monomer composition was put into the aqueous medium 1 while maintaining the rotation speed of t.k.homo MIXER at 15,000rpm, and 10.0 parts of t-butyl peroxypivalate as a polymerization initiator was added thereto. Granulation was carried out as it is for 10 minutes while maintaining the stirrer at 15,000 rpm.

(polymerization step and distillation step)

After the granulation step, the stirrer was replaced with a propeller stirring blade, and polymerization was carried out by holding at 70℃for 5.0 hours and stirring at 150rpm, and then the temperature was raised to 85℃to further carry out polymerization. Thereafter, the reflux tube of the reaction vessel was replaced with a cooling tube, the resulting slurry was heated to 100℃to distill the slurry for 6 hours, and unreacted polymerizable monomer was removed by distillation, thereby obtaining a resin particle dispersion.

< production example of external additive 1 >

External additive 1 was produced as follows.

First, 150 parts of 5% aqueous ammonia was poured into a 1.5L glass reaction vessel equipped with a stirrer, a dropping nozzle and a thermometer to prepare an alkaline catalyst solution. With simultaneous dropwise addition of 100 parts of tetraethoxysilane and 50 parts of 5% aqueous ammonia, the basic catalyst solution was adjusted to 50 ℃, then stirred, and reacted for 8 hours, thereby obtaining a silica fine particle dispersion. Thereafter, the obtained silica fine particle dispersion liquid is dried by spray drying, and pulverized with a pin mill to obtain silica fine particles. Here, by appropriately changing the above production conditions, the external additive 1 having different number average particle diameters R of the primary particles is obtained.

< production example of toner 1 >

First, 100.00 parts of toner particles 1 and 1.00 parts of external additive 1 were placed in a henschel mixer (manufactured by Nippon cowe & Engineering co., ltd., FM 10C) containing water at 7 ℃ in a jacket.

Once the water temperature in the jacket stabilized at 7±1 ℃, mixing was performed for 10 minutes at a circumferential speed of 38 m/sec for the rotating blades. During mixing, the amount of water passing through the jacket was appropriately adjusted so that the temperature in the tank of the henschel mixer did not exceed 25 ℃. The resultant mixture was screened with a 75 μm sieve, thereby obtaining toner 1.

< production example of toner 2 >

The following materials were stirred and mixed with a common stirring apparatus:

a polymerizable monomer; 74 parts of styrene and 26 parts of n-butyl acrylate

Coloring agent: 7 parts of carbon black (trade name: #25B, manufactured by Mitsubishi Chemical Corporation)

Crosslinking agent: 0.74 part of divinylbenzene

A charge control agent: 0.37 part of a styrene/acrylic resin (trade name: FCA-592P, manufactured by Fujikura Kasei Co., ltd.)

Molecular weight modifier: 1 part tetraethylthiuram disulfide

Macromer: 0.25 part of a polymethacrylate macromer (trade name: AA6, manufactured by Toagosei Chemical Industry co., ltd. Times., glass transition temperature tg=94℃)

After that, each component was uniformly dispersed with a medium type disperser, and heated to 63 ℃.

Then, 20 parts of wax a-1 was added to the uniformly dispersed material, mixed and dissolved therein to obtain a polymerizable monomer composition.

In addition, an aqueous solution obtained by dissolving 4.1 parts of sodium hydroxide in 50 parts of ion-exchanged water was gradually added to an aqueous solution obtained by dissolving 7.4 parts of magnesium chloride in 250 parts of ion-exchanged water under stirring in a stirring tank at room temperature to prepare a magnesium hydroxide colloidal dispersion (3.0 parts of magnesium hydroxide).

The above polymerizable monomer composition was put into the magnesium hydroxide colloidal dispersion obtained as described above at room temperature, the temperature was raised to 60 ℃, and the mixture was stirred until the droplets became stable. To this was added 5 parts of t-butylperoxy-2-ethylhexanoate (trade name: PERBUTYL O, manufactured by NOF Corp.) as a polymerization initiator. Thereafter, high shear stirring was performed at a rotation speed of 15,000rpm using an in-line emulsification disperser (trade name: MILDER, manufactured by Pacific Machinery & Engineering Co., ltd.) and droplets of the polymerizable monomer composition were formed.

The magnesium hydroxide colloidal dispersion in which the droplets of the polymerizable monomer composition were dispersed was placed in a reactor equipped with an impeller, the temperature was raised to 89 ℃ and controlled to be constant, and polymerization was carried out. Subsequently, when the polymerization conversion reached 98%, the system temperature was lowered to 75 ℃, and after reaching 75 ℃, 15 minutes, 3 parts of methyl methacrylate as a polymerizable monomer for the shell and 0.36 part of 2,2' -azobis [ 2-methyl-N- (1, 1-bis (hydroxymethyl) 2-hydroxyethyl) propionamide ] tetrahydrate (trade name: VA086, manufactured by FUJIFILM Wako Pure Chemical Corporation) dissolved in 10 parts of ion-exchanged water were added. After further continuing the polymerization for 3 hours, the reaction was stopped to obtain an aqueous dispersion of colored resin particles having a pH of 9.5.

Then, the aqueous dispersion of colored resin particles was heated to 80℃at 0.6m ³ The nitrogen flow rate of/(hr.kg) was stripped for 5 hours and then cooled to 25 ℃. Next, while stirring the resulting aqueous dispersion at 25 ℃, the pH of the system was adjusted to 6.5 or less with sulfuric acid for pickling, water was separated by filtration, then 500 parts of ion-exchanged water was newly added for reslurrying and washing with water. Thereafter, the dehydration and washing are repeatedNext, to separate the solid content by filtration, then the solid content was placed in a dryer, and dried at 40 ℃ for 12 hours, thereby obtaining toner particles 2.

To 100 parts of the toner particles obtained as described above, 0.7 part of hydrophobized silica fine particles having a uniform secondary particle diameter of 7nm and 1 part of hydrophobized silica fine particles having a uniform secondary particle diameter of 50nm were added and mixed using a high-speed Mixer (trade name: FM Mixer, manufactured by Nippon Coke & engineering co., ltd.) to produce toner 2.

Example 1

The following evaluation was performed by using the electrophotographic photosensitive member 1 and the toner 1. The evaluation results are shown in tables 10-1 to 10-2.

< evaluation method >

< evaluation of transferability >

A commercial laser beam printer LBP7700C manufactured by Canon inc. The modification includes changing the main unit and software of the evaluating apparatus to provide a developing roller having a rotation speed of 360 mm/sec.

The toner was filled into a toner cartridge of the evaluation apparatus LBP7700C, and the toner cartridge was left for 24 hours in an ambient temperature, humidity (25 ℃,50% rh; hereinafter also referred to as N/N) environment. After 24 hours of standing in this environment, the toner cartridge was mounted to the above-described apparatus, and 500 prints of an image having a print percentage of 5.0% were laterally printed in the center portion of the A4 paper with a margin of 50mm on both left and right sides in an N/N environment. The paper used was plain paper CS-680 (68 g/m) ² )(Canon Marketing Japan Inc.)。

For evaluation, solid images were output at the start of use (after first printing) and after 500 times of printing (after long-term use), and toner not transferred on the photosensitive member during solid image formation was peeled off by pasting using a transparent polyester tape.

The concentration difference was calculated by subtracting the concentration of the adhesive tape attached only to the paper from the concentration of the release adhesive tape attached to the paper. Concentration measurements were made at five locations to determine the arithmetic mean thereof. The difference in density (referred to as transfer residual density) is rated as follows. Note that the concentration was measured with an X-Rite color reflectance concentration meter (manufactured by X-Rite, incorporated, X-Rite 500 series).

(evaluation criteria)

A: transfer residual concentration of less than 0.20

B: a transfer residual concentration of 0.20 or more and less than 0.50

C: a transfer residual concentration of 0.50 or more and less than 1.0

D: the transfer residual concentration is 1.0 or more

< evaluation of roughness >

After outputting a character image with a printing rate of 1% by modifying the machine at 30 ℃ and 80% rh, a halftone (20H) image was formed to evaluate the roughness (density uniformity) of the image based on the following criteria. The paper used was plain paper CS-680 (68 g/m) ² ) (Canon Marketing Japan inc.). Note that when 256 gradations are represented by hexadecimal numbers, where 00H represents solid white (non-image), and FFH represents solid black (full image), the "20H of image" is a value representing a halftone image.

Roughness was evaluated based on the following criteria. The concentration was measured at 20 positions, and the measurement was performed from the concentration difference (referred to as concentration uniformity) between the maximum value and the minimum value as follows. Note that the concentration was measured with an X-Rite color reflection densitometer (manufactured by X-Rite, incorporated, X-Rite 500 series).

(evaluation criteria)

A: concentration uniformity of less than 0.04

B: the uniformity of concentration is more than 0.04 and less than 0.06

C: the uniformity of concentration is more than 0.06 and less than 0.08

D: the uniformity of concentration is more than 0.08

< evaluation of durability concentration transition >

Concentration transitions were evaluated by endurance tests with the retrofit machine in an environment of 30 ℃ and 80% RH. Outputting an initial image in which solid black patches of 20mm square are arranged at 5 points of a development area, and setting a development bias so that initial reflection is intenseThe degree was 1.3. Next, 10,000 character images with a printing rate of 1% are output. The paper used was plain paper CS-680 (68 g/m) ² ) (Canon Marketing Japan inc.). Durability was evaluated by comparing the difference in image density between the five-point average density of the solid black patch and the initial image density after the durability test.

Note that the image density was measured by using "Macbeth Reflection Densitometer RD918" manufactured by Macbeth as the relative density of the initial image with respect to the white portion.

< evaluation criteria >

A: the concentration difference is less than 0.10

B: the concentration difference is more than 0.10 and less than 0.15

C: the concentration difference is more than 0.15 and less than 0.20

D: the concentration difference is more than 0.20

Examples 2 to 72

As shown in table 4, evaluation was performed in the same manner as in example 1 with the combination of the electrophotographic photosensitive member and the toner. The evaluation results are shown in Table 10-1 and Table 10-2.

Comparative examples 1 to 32, 34 and 35

As shown in table 4, the combination of the electrophotographic photosensitive member and the toner was used for evaluation in the same evaluation method as in example 1. The evaluation results are shown in Table 10-1 and Table 10-2.

Example 73

Evaluation was performed in the same manner as in example 1 by using the electrophotographic photosensitive member 73 and the toner 2, and the following electrophotographic apparatuses. The evaluation results are shown in Table 10-1 and Table 10-2.

A monochromatic laser printer HL-5200 manufactured by Brother Industries, ltd. A high voltage power supply control system (model 615-3, manufactured by TREK INCORPORATED) is used as a power supply to power the corona charger from outside the printer. The system was adjusted so that the amount of current flowing in the corona wire of the corona charger was 500. Mu.A.

The toner in the toner cartridge of the printer is taken out, and the toner 2 is filled in its position. Further, the electrophotographic photosensitive member of the drum unit was removed, and instead, the electrophotographic photosensitive member 73 whose initial film thickness had been measured was provided for durability evaluation.

Comparative example 33

By using the electrophotographic photosensitive member 106 and the toner 2, evaluation was performed in the same manner as in example 73. The evaluation results are shown in Table 10-1 and Table 10-2.

TABLE 10-1

TABLE 10-2

The disclosure of the present embodiment includes the following constitution.

[ constitution 1]

An electrophotographic photosensitive member includes a support and a photosensitive layer on the support,

the surface layer has particles partially exposed from the surface layer among particles contained in the surface layer, the particles having a volume average particle diameter of 50.0nm or more and 350.0nm or less;

[ constitution 2]

The electrophotographic photosensitive member according to configuration 1, wherein the photosensitive layer has a charge generating layer and a charge transporting layer on the charge generating layer, the charge transporting layer being a surface layer.

[ constitution 3]

The electrophotographic photosensitive member according to configuration 1, wherein the photosensitive layer has a charge generating layer and a charge transporting layer on the charge generating layer, and the electrophotographic photosensitive member further comprises a protective layer on the photosensitive layer, the protective layer being a surface layer.

[ constitution 4]

The electrophotographic photosensitive member according to configuration 1, wherein the photosensitive layer is a single-layer type photosensitive layer, and the electrophotographic photosensitive member further comprises a protective layer on the photosensitive layer, the protective layer being a surface layer.

[ constitution 5]

The electrophotographic photosensitive member according to any one of constituting 1 to 4, wherein S1/(s1+s2) satisfies the following formula (a), wherein S1 is a total area of exposed portions of particles partially exposed from the surface layer when the surface layer is viewed from above, and S2 is a total area of exposed portions of particles other than the particles partially exposed from the surface layer when the surface layer is viewed from above,

S1/(S1+S2) is not more than 0.15 and not more than 0.80.

[ constitution 6]

The electrophotographic photosensitive member according to configuration 5, wherein the coefficient of variation of S1/(s1+s2) is 25% or less, wherein S1 is the total area of the exposed portions of the particles partially exposed from the surface layer when the surface layer is viewed from above, and S2 is the total area of the particles other than the exposed portions of the particles partially exposed from the surface layer when the surface layer is viewed from above.

[ constitution 7]

The electrophotographic photosensitive member according to any one of claims 1 to 6, wherein SF-2 of a shape of an exposed portion of the particles is 135 or less when the surface layer is viewed from above.

[ constitution 8]

The electrophotographic photosensitive member according to any one of claims 1 to 7, wherein an average circularity of a shape of an exposed portion of the particles is 0.90 or more when the surface layer is viewed from above.

[ constitution 9]

The electrophotographic photosensitive member according to any one of the constitution 1 to 8, wherein the Young's modulus of the particles is 0.60GPa or more.

[ constitution 10]

The electrophotographic photosensitive member according to any one of the constitution 1 to 9, wherein (volume average particle diameter)/(number average particle diameter) of the particles is 1.5 or less.

[ constitution 11]

The electrophotographic photosensitive member according to any one of claims 1 to 10, wherein the ash content of the insoluble component of methyl ethyl ketone in the surface layer during sintering is 5.0 mass% or less based on the total mass of the surface layer.

[ constitution 12]

A process cartridge integrally supporting an electrophotographic photosensitive member according to any one of the constitutions 1 to 11, and at least one unit selected from the group consisting of a charging unit and a developing unit, wherein the process cartridge is detachably mounted to the electrophotographic photosensitive member.

[ constitution 13]

An electrophotographic apparatus includes an electrophotographic photosensitive member according to any one of the constitutions 1 to 11, a charging unit, a developing unit, and a transfer unit.

The present invention is not limited to the above-described embodiments, and various changes and modifications may be made without departing from the spirit and scope of the present invention. To apprise the disclosure of the scope of the present invention, the following claims are made.

The present application claims priority from Japanese patent application Nos. 2021-098347 filed on 11/6/2021 and Japanese patent application No.2022-089699 filed on 1/6/2022, which are incorporated herein by reference in their entireties.

[ list of reference numerals ]

1a to 1d: electrophotographic photosensitive member

2a to 2d: charging roller

3a to 3d: exposure unit

4a to 4d: developing unit

5a to 5d: cleaning unit

10: intermediate conveyor belt

11: driving roller

12: tension roller

13: counter roller

14: metal roller

20: secondary transfer roller

21: transfer power supply

22: current regulating diode

50: paper feeding unit 50

P: transfer material

101 Particles 201, 301

102 203 charge transport layer

103 204 charge generating layer

104 205, 304 support

202 302 protective layer (surface layer)

303. Single-layer photosensitive layer

401. Exposed portions of the particles

402. Except for the exposed portions of the particles

601. Exposed part of

602. Surface of surface layer

Claims

1. An electrophotographic photosensitive member includes a support and a photosensitive layer on the support,

Characterized in that the surface layer of the electrophotographic photosensitive member contains particles,

the surface layer having particles partially exposed from the surface layer among the particles contained in the surface layer,

the particles have a volume average particle diameter of 50.0nm or more and 350.0nm or less;

in a cross section of the surface layer, the number of particles partially exposed from the surface layer is 80% or more based on the total number of the particles contained in the surface layer; and

2. An electrophotographic photosensitive member according to claim 1, wherein the photosensitive layer has a charge generating layer and a charge transporting layer on the charge generating layer, the charge transporting layer being the surface layer.

3. The electrophotographic photosensitive member according to claim 1, wherein the photosensitive layer has a charge generation layer and a charge transport layer on the charge generation layer, and the electrophotographic photosensitive member further comprises a protective layer on the photosensitive layer, the protective layer being the surface layer.

4. The electrophotographic photosensitive member according to claim 1, wherein the photosensitive layer is a single-layer photosensitive layer, and the electrophotographic photosensitive member further comprises a protective layer on the photosensitive layer, the protective layer being the surface layer.

5. The electrophotographic photosensitive member according to any one of claims 1 to 4, wherein S1/(s1+s2) satisfies the following formula (a), wherein S1 is a total area of exposed portions of particles partially exposed from the surface layer when the surface layer is viewed from above, and S2 is a total area of exposed portions of particles other than partially exposed from the surface layer when the surface layer is viewed from above,

S1/(S1+S2) is not more than 0.15 and not more than 0.80.

6. The electrophotographic photosensitive member according to claim 5, wherein a coefficient of variation of S1/(s1+s2) is 25% or less, wherein S1 is a total area of exposed portions of the particles when the surface layer is viewed from above, and S2 is a total area other than the exposed portions of the particles when the surface layer is viewed from above.

7. The electrophotographic photosensitive member according to any one of claims 1 to 6, wherein SF-2 of a shape of an exposed portion of the particles is 135 or less when the surface layer is viewed from above.

8. The electrophotographic photosensitive member according to any one of claims 1 to 7, wherein an average circularity of a shape of an exposed portion of the particles is 0.90 or more when the surface layer is viewed from above.

9. The electrophotographic photosensitive member according to any one of claims 1 to 8, wherein the young's modulus of the particles is 0.60GPa or more.

10. The electrophotographic photosensitive member according to any one of claims 1 to 9, wherein the volume average particle diameter/number average particle diameter of the particles is 1.5 or less.

11. The electrophotographic photosensitive member according to any one of claims 1 to 10, wherein the ash content of the methyl ethyl ketone insoluble component in the surface layer during sintering is 5.0 mass% or less based on the total mass of the surface layer.

12. A process cartridge, characterized in that it integrally supports the electrophotographic photosensitive member according to any one of claims 1 to 11, and at least one unit selected from the group consisting of a charging unit and a developing unit, wherein said process cartridge is detachably mounted to said electrophotographic photosensitive member.

13. An electrophotographic apparatus, characterized in that it comprises the electrophotographic photosensitive member according to any one of claims 1 to 11, a charging unit, a developing unit, and a transfer unit.