JP2016095340A - Electrophotographic photoreceptor, electrophotographic image forming apparatus, and process cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor that has an improved cleaning property, excellent wear resistance of a surface layer, and excellent fogging resistance.SOLUTION: An electrophotographic photoreceptor includes a conductive support, and a photosensitive layer and a surface layer sequentially provided on the conductive support. The surface layer is formed of a resin and includes organic particles having a diameter of 100 nm or more and 1500 nm or less. The organic particle has an inorganic film formed of a first metal oxide provided at least in part of its surface. The inorganic film is coupled to the resin with a component derived from a first organic compound including a first inorganic-side reactive group coupled to the surface of the inorganic film and a first organic-side reactive group coupled to the resin.SELECTED DRAWING: None

Description

  The present invention relates to an electrophotographic photosensitive member having a surface layer on a photosensitive layer, and relates to an electrophotographic image forming apparatus and a process cartridge provided with the electrophotographic photosensitive member.

  For various purposes, it has been proposed to add organic particles to the surface layer of an electrophotographic photoreceptor (Patent Document 1, etc.). For example, it has been confirmed that the cleaning property of the electrophotographic photosensitive member is improved by adding organic particles such as PTFE (polytetrafluoroethylene) particles or melamine-formaldehyde particles to the surface layer of the electrophotographic photosensitive member. The reason why this effect can be obtained is that PTFE particles have a small van der Waals force, or irregularities are formed on the surface of the electrophotographic photoreceptor due to the particle diameter of PTFE particles, etc. It is conceivable that the adhesion force (electrostatic adhesion force) of the surface layer of the electrophotographic photosensitive member to the toner is reduced.

JP-A-5-224453

  However, if PTFE particles or the like are added to the surface layer of the electrophotographic photosensitive member in order to improve the cleaning property of the electrophotographic photosensitive member, the abrasion resistance of the surface layer may be reduced, and the fog resistance may be reduced. May invite. SUMMARY OF THE INVENTION An object of the present invention is to provide an electrophotographic photosensitive member that has excellent surface layer abrasion resistance and fog resistance while improving cleaning properties.

  The electrophotographic photosensitive member of the present invention includes a conductive support, and a photosensitive layer and a surface layer that are sequentially provided on the conductive support. The surface layer is made of resin and includes organic particles having a diameter of 100 nm to 1500 nm. An inorganic film made of the first metal oxide is provided on at least a part of the surface of the organic particles. The inorganic film is bonded to the resin by a component derived from a first organic compound including a first inorganic side reactive group bonded to the surface of the inorganic film and a first organic side reactive group bonded to the resin.

The organic particles are preferably made of a compound having a melamine structure. The first metal oxide is preferably SiO ₂ or TiO ₂ . The first organic side reactive group is preferably an acryloyl group or a methacryloyl group.

  The surface layer preferably further includes inorganic particles made of the second metal oxide. The inorganic particle is bonded to the resin by a component derived from the second organic compound including the second inorganic side reactive group bonded to the surface of the inorganic particle and the second organic side reactive group bonded to the resin. Is preferred.

  The electrophotographic image forming apparatus of the present invention includes an electrophotographic photosensitive member of the present invention, a charging unit that charges the surface of the electrophotographic photosensitive member, an exposure unit that forms an electrostatic latent image on the surface of the electrophotographic photosensitive member, And a developing unit that develops the electrostatic latent image with toner to form a toner image.

  The process cartridge of the present invention is detachably mounted on the electrophotographic image forming apparatus, and the electrophotographic photosensitive member of the present invention, a charging unit for charging the surface of the electrophotographic photosensitive member, and electrostatic on the surface of the electrophotographic photosensitive member. An exposure unit that forms a latent image and a developing unit that develops the electrostatic latent image with toner to form a toner image.

  In the electrophotographic photoreceptor of the present invention, the cleaning property is improved, the surface layer is excellent in abrasion resistance, and the fog resistance is excellent.

1 is a schematic cross-sectional view of an electrophotographic photosensitive member according to an embodiment of the present invention. It is a figure which shows typically the structure of the organic particle etc. which are contained in the surface layer in this embodiment. It is a figure which shows typically the structure of the inorganic particle etc. which are contained in the surface layer in this embodiment. 1 is a cross-sectional view illustrating a configuration of an electrophotographic image forming apparatus according to an embodiment of the present invention.

  The present invention will be described below with reference to the drawings. The addition of the organic filler to the surface layer of the electrophotographic photosensitive member in the present invention is carried out from the viewpoint of the formation of irregularities on the surface layer due to the particle size of the organic filler and the van der Waals force of the organic filler material. The effect of reducing the adhesion of the surface layer to the surface and thus improving the cleaning property of the electrophotographic photosensitive member in the electrophotographic process can be expected. However, the surface of these organic particles (organic filler) is not treated, and cannot participate in curing, for example, in the surface layer of an electrophotographic photosensitive member made of a curable resin. In particular, organic particles such as PTFE particles have low adaptability to the surface layer, and the organic particles may be detached from the surface layer by rubbing with a blade. Thus, organic particles having an untreated surface can improve the cleaning property of the electrophotographic photosensitive member by addition to the surface layer, but it is difficult to improve the wear resistance of the electrophotographic photosensitive member. Moreover, it may cause a reduction in fog resistance. In the present invention, by using organic particles whose surfaces are sequentially treated with a metal oxide and an organic compound, while maintaining the cleaning properties of the organic particles, the wear resistance of the surface layer is increased and the fog resistance is increased. It is possible to provide an electrophotographic photosensitive member that is resistant to damage.

  In the drawings of the present invention, the same reference numerals represent the same or corresponding parts. In addition, dimensional relationships such as length, width, thickness, and depth are changed as appropriate for clarity and simplification of the drawings, and do not represent actual dimensional relationships.

[Configuration of electrophotographic photoreceptor]
FIG. 1 is a schematic cross-sectional view of an electrophotographic photosensitive member according to an embodiment of the present invention. The electrophotographic photoreceptor 100 includes a conductive support 101, and a photosensitive layer 103 and a surface layer 106 that are sequentially provided on the conductive support 101. The electrophotographic photoreceptor 100 preferably further includes an intermediate layer 102 between the conductive support 101 and the photosensitive layer 103. The photosensitive layer 103 preferably includes a charge generation layer 104 provided on the intermediate layer 102 and a charge transport layer 105 provided on the charge generation layer 104. In the following, after the surface layer 106 is shown, the configuration of the electrophotographic photoreceptor 100 other than the surface layer 106 is shown.

<Configuration of surface layer>
FIG. 2A schematically shows surface-treated organic particles (described later), and FIG. 2B shows a chemical formula of the first organic compound.

  The surface layer 106 includes organic particles 201 made of resin and having a diameter of 100 nm to 1500 nm. An inorganic film 203 made of the first metal oxide is provided on at least a part of the surface 202 of the organic particle 201. The inorganic film 203 includes a first organic side reactive group 207a bonded to the surface 204 of the inorganic film 203 and a first organic side reactive group 207b bonded to a resin (resin constituting the surface layer 106). The component derived from the compound 207 is bonded to the resin constituting the surface layer 106.

  The surface layer 106 includes organic particles 201 having a diameter of 100 nm to 1500 nm. Thereby, the cleaning property of the electrophotographic photosensitive member 100 can be improved. In the present specification, the “cleaning property of the electrophotographic photosensitive member” means the ease with which the toner is removed from the surface (for example, the surface layer 106) of the electrophotographic photosensitive member 100.

  An inorganic film 203 provided on at least a part of the surface of the organic particle 201 is bonded to a resin constituting the surface layer 106 by a component derived from the first organic compound 207. Thereby, when a thermoplastic resin is used as the resin constituting the surface layer 106, the familiarity between the resin constituting the surface layer 106 and the organic particles 201 can be improved. Further, when a curable resin (including a thermosetting resin and a photocurable resin) is used as the resin constituting the surface layer 106, the organic particles 201 contribute to the curing reaction. Therefore, the strength of the surface layer 106 can be increased. Therefore, even if the surface layer 106 and the blade are in contact, the organic particles 201 can be prevented from being detached from the surface layer 106. That is, the wear resistance of the surface layer 106 can be improved.

  Further, since the inorganic film 203 provided on at least a part of the surface of the organic particle 201 is bonded to a resin (resin constituting the surface layer 106) by a component derived from the first organic compound 207, the organic particle 201 Exposure from the surface layer 106 can be prevented. Thereby, it can prevent that the organic particle 201 contacts a toner. Accordingly, since the rubbing between the surface layer 106 and the toner spikes can be prevented, a decrease in the surface potential of the electrophotographic photoreceptor 100 can be prevented. Therefore, the fog resistance can be increased.

  Note that no reaction point with the first organic compound 207 exists on the surface 202 of the organic particle 201. Therefore, it is difficult to bond the first organic compound 207 to the surface 202 of the organic particle 201. However, in this embodiment, the inorganic film 203 is provided on at least a part of the surface 202 of the organic particle 201. Here, since the inorganic film 203 is made of the first metal oxide, a hydroxyl group (—OH group) exists on the surface 204 of the inorganic film 203. Since this hydroxyl group functions as a reaction point with the first inorganic side reactive group 207 a, the first organic compound 207 can be bonded to the organic particles 201 through the inorganic film 203.

  The material of the first metal oxide can be confirmed by X-ray photoelectron spectroscopy, and the material of the first organic compound 207 can be confirmed using a gas chromatograph mass spectrometer. Therefore, by combining X-ray photoelectron spectroscopy and gas chromatography mass spectrometry, the inorganic layer 203 provided on at least a part of the surface of the organic particle 201 is changed to the surface layer 106 by a component derived from the first organic compound 207. It can be confirmed whether it is couple | bonded with resin which comprises.

  The thickness of the surface layer 106 is preferably 0.2 μm or more and 10 μm or less, and more preferably 0.5 μm or more and 6 μm or less. Below, the material contained in the surface layer 106 is shown in order.

(Resin constituting the surface layer)
As the resin constituting the surface layer 106, a conventionally known resin can be used as the resin constituting the surface layer of the electrophotographic photosensitive member. The resin constituting the surface layer 106 may be a thermoplastic resin such as a polyester resin or a polycarbonate resin, or may be a mixture of a thermoplastic resin and a curable resin, but is preferably a curable resin. .

  The curable resin contains a component obtained by curing (for example, thermosetting or photocuring) of the curable compound, and is preferably composed of such a component. The “curable compound” means a monomer or oligomer that is polymerized by the above curing, and is preferably a radical polymerizable compound. The “radical polymerizable compound” means a compound that undergoes a radical polymerization reaction by heat irradiation, electromagnetic wave irradiation, electron beam irradiation, or the like and is thereby polymerized. Therefore, when the curable compound is a radical polymerizable compound, the curable resin contains the curable compound as a repeating unit.

  The radical polymerizable compound preferably contains at least one of an acryloyl group and a methacryloyl group as a radical polymerizable reactive group (functional group contributing to the radical polymerization reaction). As a result, acryloyl groups, methacryloyl groups, or acryloyl groups and methacryloyl groups are radically polymerized and polymerized. As such a radically polymerizable compound, for example, compounds represented by the following chemical formulas (1) to (15) can be used. In the following chemical formulas (1) to (15), R represents an acryloyl group represented by the following chemical formula (16), and R ′ represents a methacryloyl group represented by the following chemical formula (17). By measuring the infrared absorption spectrum according to infrared spectroscopy, the resin material constituting the surface layer can be confirmed.

(Organic particles)
The diameter of the organic particles 201 is preferably 200 nm or more and 1500 nm or less, and more preferably 500 nm or more and 1000 nm or less. Thereby, the cleaning property of the electrophotographic photoreceptor 100 can be further improved. The “diameter of the organic particles 201” means a median diameter D50 when the particle size distribution of the organic particles 201 is measured on a volume basis, and is obtained using, for example, a dynamic light scattering particle size distribution measuring apparatus.

  As the material of the organic particles 201, a conventionally known material can be used as a material of organic particles added to the surface layer of the electrophotographic photosensitive member in order to improve the cleaning property of the electrophotographic photosensitive member. The organic particles 201 are preferably PTFE particles, melamine-formaldehyde particles, or styrene-acrylic particles, and more preferably melamine-formaldehyde particles. If the organic particles 201 are melamine-formaldehyde particles, the cleaning property of the electrophotographic photoreceptor 100 can be further enhanced by the positive charging property of the melamine-formaldehyde particles. Moreover, even if the organic particles 201 are melamine-formaldehyde particles, the fog resistance can be increased.

  Specifically, in the conventional electrophotographic photosensitive member, the surface layer does not include surface-treated organic particles. Therefore, the affinity between the organic particles and the resin constituting the surface layer is low, and thus the organic particles may be exposed from the surface layer of the electrophotographic photosensitive member. When melamine-formaldehyde particles are used as the organic particles, the organic particles have positive chargeability. On the other hand, the toner is negatively charged on the electrophotographic photosensitive member. Therefore, when the melamine-formaldehyde particles are exposed from the surface layer, an electrostatic interaction occurs between the melamine-formaldehyde particles and the toner spikes, and as a result, the melamine-formaldehyde particles and the toner spikes are scratched. Is likely to occur. As a result, the surface potential of the electrophotographic photosensitive member is likely to be lowered, and the fog resistance is likely to be lowered.

  However, in the present embodiment, since the organic particles 201 and the resin constituting the surface layer 106 are bonded, it is possible to prevent the organic particles 201 from being exposed from the surface layer 106. Thereby, even when melamine-formaldehyde particles are used as the organic particles 201, it is possible to prevent the occurrence of electrostatic interaction between the organic particles 201 and the toner spikes. Scratching with toner spikes can be prevented. Therefore, the surface potential of the electrophotographic photoreceptor 100 can be prevented from being lowered, and the fog resistance can be increased. As described above, in the present embodiment, it is possible to prevent a reduction in fog resistance that becomes remarkable when the organic particles 201 are melamine-formaldehyde particles.

“Melamine-formaldehyde particles” means particles composed of melamine-formaldehyde. “Melamine-formaldehyde” means a compound (for example, melamine resin) obtained by condensation polymerization after formaldehyde is added to melamine, and means a compound having a melamine structure. “Melamine structure” means that one or more hydrogen atoms contained in an amino group (—NH ₂ ) bonded to the six-membered ring of melamine are substituted with other substituents, or are contained in the amino group. It means that one or more hydrogen atoms are eliminated. “Melamine-formaldehyde” may have a melamine structure in a part of the molecule, or may have a melamine structure as a repeating unit. In the former case, the number of melamine structures contained in one molecule of melamine-formaldehyde is not particularly limited. In the latter case, the degree of polymerization of the melamine structure in melamine-formaldehyde is not particularly limited.

  “Styrene-acrylic particles” means particles made of styrene-acrylic. “Styrene-acrylic” means a compound obtained by radical polymerization of styrene and acrylic. The degree of polymerization of styrene and acrylic in this compound is not particularly limited. The material of the organic particles 201 can be examined using a gas chromatography mass spectrometer.

  When the resin constituting the surface layer 106 is a curable resin, the organic particles 201 are preferably included in an amount of 5 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the curable compound (monomer). More preferably, it is contained in an amount of not less than 30 parts by mass. When the resin constituting the surface layer 106 is a thermoplastic resin, the organic particles 201 are preferably included in an amount of 5 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the thermoplastic resin. More preferably, 30 parts by mass or less is included. Thereby, the cleaning property of the electrophotographic photoreceptor 100 can be further improved. The content of the organic particles 201 can be examined using a gas chromatography mass spectrometer.

(Inorganic film)
The inorganic film 203 is provided on at least a part of the surface 202 of the organic particle 201. “The inorganic film 203 is provided on at least a part of the surface 202 of the organic particle 201” means that the coverage of the inorganic film 203 on the surface 202 of the organic particle 201 is 50% or more. When the coverage is 50% or more, a reaction point with the first organic compound 207 can be secured on the surface 204 of the inorganic film 203.

The material of the first metal oxide is not particularly limited. For example, as the first metal oxide, a metal oxide having a specific gravity of 5.0 or less is preferably used, and a metal oxide having a specific gravity of 2.0 or less is more preferable. If the specific gravity of the first metal oxide is 5.0 or less, organic particles (“organic particles coated with the inorganic film 203” formed by providing the inorganic film 203 on at least a part of the surface 202 of the organic particles 201 are used. 205 ”) can be prevented from becoming too large. Thereby, in the coating liquid (surface layer forming liquid) used when forming the surface layer 106, the organic particles 205 covered with the inorganic film 203 can be present in a stable state. Formation of aggregates of the coated organic particles 205 can be prevented. Therefore, it is possible to prevent the protrusions that cause deterioration of the cleaning property of the electrophotographic photoreceptor 100 from being formed on the upper surface of the surface layer 106. For example, the first metal oxide is preferably SiO ₂ or TiO ₂ .

Further, if the first metal oxide is SiO ₂ or TiO ₂ , a hydroxyl group exists on the surface 204 of the inorganic film 203. Also from this point, the first metal oxide is preferably SiO ₂ or TiO ₂ . The material of the first metal oxide can be confirmed by X-ray photoelectron spectroscopy.

  The first metal oxide is preferably contained in an amount of 1% by mass to 50% by mass with respect to the organic particles 201. If the first metal oxide is contained in an amount of 1% by mass or more with respect to the organic particles 201, it is easy to secure a reaction point with the first organic compound 207 on the surface 204 of the inorganic film 203. If the first metal oxide is contained in an amount of 50% by mass or less based on the organic particles 201, the mass of the organic particles 205 covered with the inorganic film 203 can be prevented from becoming too large. Thereby, it is possible to further prevent the protrusions that cause deterioration of the cleaning property of the electrophotographic photoreceptor 100 from being formed on the upper surface of the surface layer 106 (described above). More preferably, the first metal oxide is included in an amount of 5% by mass to 30% by mass with respect to the organic particles 201. By measuring the weight loss by thermogravimetry / differential thermal analysis, the content (% by mass) of the first metal oxide can be determined.

(First organic compound)
The first organic compound 207 includes a first inorganic side reactive group 207 a bonded to the surface of the inorganic film 203 and a first organic side reactive group 207 b bonded to the resin constituting the surface layer 106. As an example of the 1st organic compound 207, the silane coupling agent containing the 1st inorganic side reaction group 207a and the 1st organic side reaction group 207b is mentioned (FIG.2 (b)). The material of the first organic compound 207 can be confirmed using a gas chromatograph mass spectrometer.

Here, in FIG. 2A and FIG. 2B, R ₂ represents a hydrocarbon group, preferably a methyl group. n represents an integer of 1 or more, and is preferably 3. “AC / MAC” means AC or MAC, “AC” means an acryloyl group represented by the chemical formula (16), and “MAC” represents a methacryloyl group represented by the chemical formula (17). means.

The first organic compound 207 shown in FIG. 2B includes three alkoxy groups (—OR ₂ ) as the first inorganic reactive group 207a. The first inorganic reactive group 207a is not limited to an alkoxy group as long as it is a functional group capable of reacting with a hydroxyl group present on the surface 204 of the inorganic film 203 (for example, dehydration condensation reaction). Further, the number of first inorganic side reactive groups 207a included in the first organic compound 207 is not limited to three.

  The first organic compound 207 shown in FIG. 2B includes one acryloyl group or one methacryloyl group as the first organic side reactive group 207b. The first organic-side reactive group 207b is not limited to an acryloyl group or a methacryloyl group as long as it is a functional group capable of reacting with a radical polymerizable reactive group contained in the curable compound (for example, radical polymerization reaction). Further, the number of first organic side reactive groups 207b included in the first organic compound 207 is not limited to one.

Since the reaction between the first inorganic side reactive group 207a and the hydroxyl group is a dehydration condensation reaction, the hydroxyl group is eliminated from the surface 204 of the inorganic film 203 by this reaction, and an alkoxy group (first inorganic side reactive group 207a) is obtained. The hydrocarbon group (R _{2 in} FIG. 2B) is released from (an example of FIG. 2) (FIG. 2A). On the other hand, since the reaction between the first organic side reactive group 207b and the radical polymerizable reactive group is a radical polymerization reaction, the functional group is not eliminated by this reaction (FIG. 2 (a)). Therefore, “the component derived from the first organic compound 207” means that the functional group (for example, R _{2 in} FIG. 2B) included in the first inorganic side reactive group 207a is the first organic compound 207. It means something out of the range. Before and after the dehydration condensation reaction, the material of the organic particles 201, the shape of the organic particles 201 (for example, the diameter of the organic particles 201), the composition of the first metal oxide, and the shape of the inorganic film 203 are not changed. The same applies before and after the radical polymerization reaction.

  If the first organic compound 207 is a silane coupling agent containing the first inorganic side reactive group 207a and the first organic side reactive group 207b, the steric hindrance during the reaction between the first inorganic side reactive group 207a and the hydroxyl group. Can be kept small, and the reaction easily occurs. Moreover, since the steric hindrance at the time of reaction with the 1st organic side reactive group 207b and the said radical polymerizable reactive group can be restrained small, the reaction becomes easy to occur.

  It is preferable that the 1st organic compound 207 is contained 1 mass% or more and 20 mass% or less with respect to the organic particle 201. FIG. When the first organic compound 207 is contained in an amount of 1% by mass or more with respect to the organic particles 201, the organic particles 201 and the resin constituting the surface layer 106 are easily bonded by the component derived from the first organic compound 207. If the first organic compound 207 is contained in an amount of 20% by mass or less with respect to the organic particles 201, the first organic compound 207 can be prevented from being present in the surface layer 106 without being bonded to the surface 204 of the inorganic film 203. . More preferably, the first organic compound 207 is included in an amount of 5% by mass to 10% by mass with respect to the organic particles 201. The content (% by mass) of the first organic compound 207 can be determined using a gas chromatograph mass spectrometer.

(Surface-treated organic particles)
“Surface treated organic particles 210” refers to organic particles 201, an inorganic film 203 provided on at least a part of the surface 202 of the organic particles 201, and a first organic compound bonded to the surface 204 of the inorganic film 203. The structure which has the component originating in 207 is meant. For example, when the silane coupling agent shown in FIG. 2B is used as the first organic compound 207, the “surface-treated organic particles 210” can be paraphrased as organic particles to which the silane coupling agent is bound.

  When the resin constituting the surface layer 106 is a curable resin, the surface-treated organic particles 210 may be contained in an amount of 5 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the curable compound (monomer). preferable. If the surface-treated organic particles 210 are contained in an amount of 5 parts by mass or more with respect to 100 parts by mass of the curable compound (monomer), the wear resistance of the surface layer 106 can be further increased, and the fog resistance is further increased. And the cleaning property of the electrophotographic photoreceptor 100 can be further enhanced. On the other hand, if the surface-treated organic particles 210 are contained in an amount of 50 parts by mass or less with respect to 100 parts by mass of the curable compound (monomer), the adhesion of the surface layer 106 to the toner can be reduced. More preferably, the surface-treated organic particles 210 are contained in an amount of 10 to 30 parts by mass with respect to 100 parts by mass of the curable compound (monomer).

  When the resin constituting the surface layer 106 is a thermoplastic resin, the surface-treated organic particles 210 are preferably included in an amount of 5 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the thermoplastic resin. If the surface-treated organic particles 210 are contained in an amount of 5 parts by mass or more with respect to 100 parts by mass of the thermoplastic resin, the abrasion resistance of the surface layer 106 can be further increased, and the fog resistance can be further increased. The cleaning property of the electrophotographic photoreceptor 100 can be further enhanced. On the other hand, if the surface-treated organic particles 210 are contained in an amount of 50 parts by mass or less with respect to 100 parts by mass of the thermoplastic resin, the adhesion of the surface layer 106 to the toner can be reduced. More preferably, the surface-treated organic particles 210 are contained in an amount of 10 to 30 parts by mass with respect to 100 parts by mass of the thermoplastic resin. By measuring the amount of nitrogen atoms by X-ray photoelectron spectroscopy, the content of the surface-treated organic particles 210 can be examined.

(Inorganic particles)
It is preferable that the surface layer 106 further includes inorganic particles made of the second metal oxide. Thereby, charge transportability can be imparted to the surface layer 106.

  The inorganic particles preferably have a diameter of 5 nm to 300 nm. When the diameter of the inorganic particles is 5 nm or more and 300 nm or less, the conductivity of the surface layer 106 and the hardness of the surface layer 106 can be increased. The diameter of the inorganic particles is preferably 10 nm or more and 150 nm or less, and more preferably 20 nm or more and 100 nm or less. “The diameter of the inorganic particles” means the median diameter D50 when the particle size distribution of the inorganic particles is measured on a volume basis, and is measured by the same method as the method of measuring the diameter of the organic particles 201.

The material of the second metal oxide constituting the inorganic particles is not particularly limited, but is preferably SnO ₂ or TiO ₂ . Thereby, since a hydroxyl group exists on the surface of the inorganic particles, a reaction point with the second organic compound (described later) can be secured on the surface of the inorganic particles. The material of the second metal oxide can be confirmed by X-ray photoelectron spectroscopy.

  When the resin constituting the surface layer 106 is a curable resin, the inorganic particles are preferably included in an amount of 30 parts by mass or more and 200 parts by mass or less, based on 100 parts by mass of the curable resin (monomer), and 50 parts by mass. More preferably, the content is 100 parts by mass or less. When the resin constituting the surface layer 106 is a thermoplastic resin, the inorganic particles are preferably included in an amount of 30 parts by mass or more and 200 parts by mass or less, and 50 parts by mass or more and 100 parts by mass with respect to 100 parts by mass of the thermoplastic resin. More preferably, it is contained in a part or less. Thereby, further charge transport property can be imparted to the surface layer 106. By measuring the weight loss by thermogravimetry / differential thermal analysis, the content of inorganic particles can be examined.

  Such inorganic particles are components derived from the second organic compound including the second inorganic side reactive group bonded to the surface of the inorganic particle and the second organic side reactive group bonded to the resin constituting the surface layer 106. Therefore, it is preferable to be bonded to the resin constituting the surface layer 106. FIG. 3A schematically shows surface-treated inorganic particles (described later), and FIG. 3B shows a chemical formula of the second organic compound.

(Second organic compound)
The same can be said for the second organic compound 307 as for the first organic compound 207. Specifically, as an example of the second organic compound 307, a silane coupling agent including a second inorganic side reactive group 307a and a second organic side reactive group 307b can be cited (FIG. 3B). Note that the first organic compound 207 and the second organic compound 307 may have the same composition or may have different compositions. The material of the second organic compound 307 can be confirmed using a gas chromatograph mass spectrometer.

Here, in FIG. 3A and FIG. 3B, R ₃ represents a hydrocarbon group, preferably a methyl group. n represents an integer of 1 or more, and is preferably 3. “AC / MAC” means AC or MAC, “AC” means an acryloyl group represented by the chemical formula (16), and “MAC” represents a methacryloyl group represented by the chemical formula (17). means.

The second organic compound 307 shown in FIG. 3B includes _three alkoxy groups (—OR ₃ ) as the second inorganic side reactive group 307a. The second inorganic reactive group 307a is not limited to an alkoxy group as long as it is a functional group capable of reacting with a hydroxyl group present on the surface 304 of the inorganic particle 303 (for example, dehydration condensation reaction). Further, the number of second inorganic reactive groups 307a included in the second organic compound 307 is not limited to three.

  The second organic compound 307 shown in FIG. 3B includes one acryloyl group or one methacryloyl group as the second organic side reactive group 307b. The second organic side reactive group 307b is not limited to an acryloyl group or a methacryloyl group as long as it is a functional group capable of reacting with the radical polymerizable reactive group contained in the curable compound (for example, radical polymerization reaction). Further, the number of second organic side reactive groups 307b included in the second organic compound 307 is not limited to one.

Since the reaction between the second inorganic side reactive group 307a and the hydroxyl group is a dehydration condensation reaction, the hydroxyl group is eliminated from the surface 304 of the inorganic particle 303 by this reaction, and an alkoxy group (second inorganic side reactive group 307a) is obtained. The hydrocarbon group (R _{3 in} FIG. 3B) is eliminated from the example (FIG. 3A). On the other hand, since the reaction between the second organic side reactive group 307b and the radical polymerizable reactive group is a radical polymerization reaction, the functional group is not eliminated by this reaction (FIG. 3A). Therefore, the “component derived from the second organic compound 307” means that the functional group (for example, R _{3 in} FIG. 3B) included in the second inorganic side reactive group 307a is the second organic compound 307. It means something out of the range. Note that the composition of the second metal oxide and the shape of the inorganic particles 303 (for example, the diameter of the inorganic particles 303) do not change before and after the dehydration condensation reaction. The same applies before and after the radical polymerization reaction.

  If the second organic compound 307 is a silane coupling agent containing the second inorganic side reactive group 307a and the second organic side reactive group 307b, the steric hindrance during the reaction between the second inorganic side reactive group 307a and the hydroxyl group. Can be kept small, and the reaction easily occurs. Moreover, since the steric hindrance at the time of reaction with the 2nd organic side reactive group 307b and the said radical polymerizable reactive group can be suppressed small, the reaction becomes easy to occur.

  The second organic compound 307 is preferably contained in an amount of 1% by mass to 10% by mass with respect to the inorganic particles 303. If the second organic compound 307 is contained in an amount of 1% by mass or more with respect to the inorganic particles 303, the inorganic particles 303 and the resin constituting the surface layer 106 are easily bonded by the component derived from the second organic compound 307. If the second organic compound 307 is contained in an amount of 10% by mass or less with respect to the inorganic particles 303, the second organic compound 307 can be prevented from existing in the surface layer 106 without being bonded to the surface 304 of the inorganic particles 303. . More preferably, the second organic compound 307 is contained in an amount of 3% by mass to 7% by mass with respect to the inorganic particles 303. The content (% by mass) of the second organic compound 307 can be determined using a gas chromatograph mass spectrometer.

(Surface-treated inorganic particles)
“Surface-treated inorganic particle 310” means a structure having inorganic particles 303 and components derived from the second organic compound 307 bonded to the surface 304 of the inorganic particles 303. For example, when the silane coupling agent shown in FIG. 3B is used as the second organic compound 307, the “surface-treated organic particles 310” can be paraphrased as organic particles to which the silane coupling agent is bound.

  When the resin constituting the surface layer 106 is a curable resin, the surface-treated inorganic particles 310 may be included in an amount of 30 parts by mass or more and 200 parts by mass or less with respect to 100 parts by mass of the curable compound (monomer). preferable. If the surface-treated inorganic particles 310 are contained in an amount of 30 parts by mass or more with respect to 100 parts by mass of the curable compound (monomer), further charge transportability can be imparted to the surface layer 106. On the other hand, if the surface-treated inorganic particles 310 are contained in an amount of 200 parts by mass or less with respect to 100 parts by mass of the curable compound (monomer), it is possible to further prevent the reduction in fog resistance. More preferably, the surface-treated inorganic particles 310 are contained in an amount of 50 parts by mass or more and 100 parts by mass or less with respect to 100 parts by mass of the curable compound (monomer).

  When the resin constituting the surface layer 106 is a thermoplastic resin, the surface-treated inorganic particles 310 are preferably included in an amount of 30 parts by mass or more and 200 parts by mass or less with respect to 100 parts by mass of the thermoplastic resin. If the surface-treated inorganic particles 310 are contained in an amount of 30 parts by mass or more with respect to 100 parts by mass of the thermoplastic resin, further charge transport properties can be imparted to the surface layer 106. On the other hand, if the surface-treated inorganic particles 310 are contained in an amount of 200 parts by mass or less with respect to 100 parts by mass of the thermoplastic resin, the fog resistance can be further prevented from being lowered. More preferably, the surface-treated inorganic particles 310 are contained in an amount of 50 parts by mass or more and 100 parts by mass or less with respect to 100 parts by mass of the thermoplastic resin. By measuring the weight loss by thermogravimetry / differential thermal analysis, the content of the surface-treated inorganic particles 310 can be examined.

<Formation of surface layer 1>
(Preparation of organic particle 205 covered with inorganic film 203)
For example, the surface layer 106 can be formed according to the following method. First, the organic particles 201 are immersed in a solution containing the first metal oxide. Thereby, organic particles 205 covered with the inorganic film 203 are obtained.

(Production of surface-treated organic particles 210)
Next, the organic particles 205 coated with the inorganic film 203 and the first organic compound 207 are stirred in a liquid phase. As a result, the hydroxyl group on the surface 204 of the inorganic film 203 and the first inorganic-side reactive group 207a of the first organic compound 207 cause a dehydration condensation reaction, and thus the surface-treated organic particles 210 are obtained.

(Curing the coating)
Subsequently, the resin constituting the surface layer 106 and the surface-treated organic particles 210 are reacted. When a curable resin is used as the resin constituting the surface layer 106, first, a liquid (surface layer forming liquid) containing at least the curable compound and the surface-treated organic particles 210 is prepared. Next, after applying a surface layer forming liquid on the upper surface of the photosensitive layer 103 according to a conventionally known method, the formed coating film is irradiated with electromagnetic waves such as ultraviolet rays or visible light, electron beams, or heat. To do. Thereby, the radical polymerizable reactive group of the curable compound and the first organic side reactive group 207b of the surface-treated organic particles 210 cause a radical polymerization reaction (curing reaction). Therefore, the surface layer 106 is formed.

  In addition, when irradiating electromagnetic waves with respect to a coating film, it is preferable that the liquid for surface layer formation further contains a conventionally well-known photoinitiator. Moreover, when irradiating heat with respect to a coating film, it is preferable that the liquid for surface layer formation further contains a conventionally well-known thermal polymerization initiator.

  On the other hand, when a thermoplastic resin is used as the resin constituting the surface layer 106, a liquid containing at least the thermoplastic resin and the surface-treated organic particles 210 is applied to the upper surface of the photosensitive layer 103 at a high temperature. Allow to cool to room temperature. In this way, the surface layer 106 is formed.

<Formation of surface layer 2>
When forming the surface layer 106 including both the organic particles 201 and the inorganic particles 303, the surface layer 106 can be formed according to the following method.

(Preparation of surface-treated inorganic particles 310)
First, the surface-treated inorganic particles 310 are produced following the method for producing the surface-treated organic particles 210. Specifically, the inorganic particles 303 and the second organic compound 307 are stirred in a liquid phase. Thereby, the hydroxyl group of the surface 304 of the inorganic particle 303 and the second inorganic side reactive group 307a of the second organic compound 307 cause a dehydration condensation reaction, and thus the surface-treated inorganic particle 310 is obtained.

(Curing the coating)
Next, the resin constituting the surface layer 106, the surface-treated organic particles 210, and the surface-treated inorganic particles 310 are reacted. When a curable resin is used as the resin constituting the surface layer 106, first, a liquid (surface layer forming liquid) containing at least the curable compound, the surface-treated organic particles 210, and the surface-treated inorganic particles 310. ) Is prepared. Next, after applying a surface layer forming liquid on the upper surface of the photosensitive layer 103 according to a conventionally known method, the formed coating film is irradiated with electromagnetic waves such as ultraviolet rays or visible light, electron beams, or heat. To do. As a result, the radically polymerizable reactive group of the curable compound and the first organic side reactive group 207b of the surface-treated organic particles 210 cause a radical polymerization reaction (curing reaction), and the radically polymerizable reactive group of the curable compound and A radical polymerization reaction occurs with the second organic side reactive group 307b of the surface-treated inorganic particles 310 (curing reaction). Therefore, the surface layer 106 including both the organic particles 201 and the inorganic particles 303 is formed.

  On the other hand, when a thermoplastic resin is used as the resin constituting the surface layer 106, a liquid containing at least the thermoplastic resin, the surface-treated organic particles 210, and the surface-treated inorganic particles 310 is exposed at a high temperature. After coating on the upper surface of the layer 103, it is cooled to about room temperature. In this way, the surface layer 106 including both the organic particles 201 and the inorganic particles 303 is formed.

<Conductive support>
The conductive support 101 preferably has a conventionally known configuration as a conductive support for an electrophotographic photosensitive member. For example, the conductive support 101 is preferably made of a metal such as aluminum, copper, chromium, nickel, zinc, or stainless steel formed into a drum shape or a sheet shape.

<Intermediate layer>
The intermediate layer 102 preferably has a barrier function and an adhesive function, and preferably has a conventionally known structure as an intermediate layer of an electrophotographic photosensitive member (a layer provided between the conductive support and the photosensitive layer). . For example, the intermediate layer 102 is preferably formed by a dip coating method or the like using a liquid (intermediate layer forming liquid) in which a polyamide resin is dissolved in an alcohol solution. The thickness of the intermediate layer 102 is preferably 0.1 μm or more and 15 μm or less, and more preferably 0.3 μm or more and 10 μm or less.

<Photosensitive layer>
The photosensitive layer 103 may be formed of a single layer having both a charge generation function and a charge transport function. However, the photosensitive layer 103 includes a charge generation layer 104 and a charge transport layer 105 provided on the charge generation layer 104. It is preferable to have. Since the photosensitive layer 103 includes the charge generation layer 104 and the charge transport layer 105, it is possible to prevent the residual potential from increasing due to repeated use of the electrophotographic photosensitive member 100, and to control the electrophotographic characteristics according to the purpose.

(Charge generation layer)
The charge generation layer 104 preferably has a conventionally known configuration as a charge generation layer of an electrophotographic photosensitive member. For example, the charge generation layer 104 preferably includes at least a charge generation material and a binder resin, and a dispersion liquid (charge generation layer forming liquid) in which the charge generation material is dispersed in a binder resin solution is used as the intermediate layer 102. It is preferably formed by coating on the upper surface.

  The charge generation material is preferably made of a conventionally known material as a material for the charge generation material contained in the charge generation layer of the electrophotographic photosensitive member. Examples of the charge generation material include azo raw materials such as Sudan Red and Diane Blue, pyrenequinone, and anant Examples include quinone pigments such as anthrone, phthalocyanine pigments, and the like. As the charge generation material, these compounds can be used alone or in combination of two or more. The charge generation material is preferably added in an amount of 1 part by mass or more and 600 parts by mass or less, and more preferably 50 parts by mass or more and 500 parts by mass or less, relative to 100 parts by mass of the binder resin.

  The binder resin is preferably made of a conventionally known material as a binder resin material contained in the charge generation layer of the electrophotographic photosensitive member, and examples thereof include polystyrene resin, polyethylene resin, and polyvinyl butyral resin.

  The thickness of the charge generation layer 104 is preferably 0.01 μm or more and 5 μm or less, and more preferably 0.05 μm or more and 3 μm or less.

(Charge transport layer)
The charge transport layer 105 preferably has a conventionally known configuration as a charge transport layer of an electrophotographic photosensitive member. For example, the charge transport layer 105 preferably includes at least a charge transport material and a binder resin. A solution (charge transport layer forming liquid) in which the charge transport material is dissolved in a binder resin solution is used as the charge generation layer 104. It is preferably formed by coating on the upper surface.

  The charge transporting material is preferably made of a conventionally known material as a material for the charge transporting material contained in the charge transporting layer of the electrophotographic photosensitive member. Examples thereof include carbazole derivatives, oxazole derivatives, poly-N-vinylcarbazole, Examples include poly-1-vinylpyrene or poly-9-vinylanthracene. As the charge transport material, these compounds can be used alone or in admixture of two or more. The charge transport material is preferably added in an amount of 10 to 500 parts by mass, more preferably 20 to 100 parts by mass, with respect to 100 parts by mass of the binder resin.

  The binder resin is preferably made of a conventionally known material as the material of the binder resin contained in the charge transport layer of the electrophotographic photoreceptor, and examples thereof include polycarbonate resin and polyacrylate resin.

  The thickness of the charge transport layer 105 is preferably 5 μm or more and 40 μm or less, and more preferably 10 μm or more and 30 μm or less.

[Configuration of electrophotographic image forming apparatus, image forming method]
The electrophotographic image forming apparatus of the present embodiment (hereinafter sometimes simply referred to as “image forming apparatus”) includes an electrophotographic photosensitive member 100, a charging unit that charges the surface of the electrophotographic photosensitive member 100, and an electrophotographic photosensitive member. An exposure unit that forms an electrostatic latent image on the surface of the body 100 and a developing unit that develops the electrostatic latent image with toner to form a toner image are provided. Since the image forming apparatus of the present embodiment includes the electrophotographic photosensitive member 100, the surface layer 106 can be improved in wear resistance and fog resistance can be improved while improving the cleaning property of the electrophotographic photosensitive member 100. .

  The process cartridge according to this embodiment is detachably attached to the image forming apparatus, and includes an electrophotographic photoreceptor 100, a charging unit that charges the surface of the electrophotographic photoreceptor 100, and an electrostatic latent image on the surface of the electrophotographic photoreceptor 100. An exposure unit that forms an image and a developing unit that develops the electrostatic latent image with toner to form a toner image. Since the process cartridge of this embodiment includes the electrophotographic photosensitive member 100, it is possible to improve the wear resistance and the fog resistance of the surface layer 106 while improving the cleaning property of the electrophotographic photosensitive member 100. Hereinafter, a specific description will be given with reference to FIG.

  FIG. 4 is a cross-sectional view showing the configuration of the image forming apparatus of the present embodiment. The image forming apparatus shown in FIG. 4 is called a tandem color image forming apparatus, and includes four sets of image forming units (process cartridges) 10Y, 10M, 10C, and 10Bk, and an endless belt-shaped intermediate transfer member unit 7. And a sheet feeding / conveying unit 21 and a fixing unit 24. A document image reading device SC is disposed on the upper part of the apparatus main body A.

  The image forming unit 10Y forms a yellow image. The image forming unit 10Y includes a charging unit 2Y, an exposure unit 3Y, a developing unit 4Y, and a cleaning unit 6Y arranged around a drum-shaped electrophotographic photoreceptor 1Y, and further includes a primary transfer roller 5Y.

  The image forming unit 10M forms a magenta image. The image forming unit 10M includes a charging unit 2M, an exposure unit 3M, a developing unit 4M, and a cleaning unit 6M around a drum-shaped electrophotographic photosensitive member 1M, and further includes a primary transfer roller 5M.

  The image forming unit 10C forms a cyan image. The image forming unit 10C includes a charging unit 2C, an exposure unit 3C, a developing unit 4C, and a cleaning unit 6C around the drum-shaped electrophotographic photosensitive member 1C, and further includes a primary transfer roller 5C.

  The image forming unit 10Bk forms a black image. The image forming unit 10Bk includes a charging unit 2Bk, an exposure unit 3Bk, a developing unit 4Bk, and a cleaning unit 6Bk arranged around a drum-shaped electrophotographic photosensitive member 1Bk, and further includes a primary transfer roller 5Bk.

  If the electrophotographic photoreceptor 100 is used as at least one of the drum-shaped electrophotographic photoreceptor 1Y, the drum-shaped electrophotographic photoreceptor 1M, the drum-shaped electrophotographic photoreceptor 1C, and the drum-shaped electrophotographic photoreceptor 1Bk. The above-described effects (the surface layer 106 is improved in wear resistance and the fog resistance is increased while improving the cleaning property of the electrophotographic photosensitive member 100) are obtained.

  The image forming units 10Y, 10M, 10C, and 10Bk are configured similarly except that the colors of the toner images formed on the electrophotographic photoreceptors 1Y, 1M, 1C, and 1Bk are different. For this reason, the image forming unit 10Y will be described below as an example.

  In the present embodiment, at least the electrophotographic photoreceptor 1Y, the charging unit 2Y, the developing unit 4Y, and the cleaning unit 6Y are integrated in the image forming unit 10Y.

  The charging unit 2Y applies a uniform potential to the electrophotographic photoreceptor 1Y to charge (for example, negatively charge) the surface of the electrophotographic photoreceptor 1Y. As the charging unit 2Y, a non-contact charger is preferably used. For example, a corona charger such as a corotron charger or a scorotron charger can be used.

  The exposure unit 3Y exposes the surface of the electrophotographic photoreceptor 1Y to which the uniform potential is applied by the charging unit 2Y based on the image signal (yellow), and thereby, the static corresponding to the yellow image. An electrostatic latent image is formed. The exposure unit 3Y includes an LED configured by arranging light emitting elements in an array in the axial direction of the electrophotographic photoreceptor 1Y and an imaging element (trade name; SELFOC (registered trademark) lens), or A laser optical system or the like can be used.

  The developing unit 4Y develops the electrostatic latent image formed by the exposure unit 3Y with toner to form a toner image. The toner to be used is not particularly limited, but is preferably a dry developer.

  In the image forming apparatus of the present embodiment, the electrophotographic photosensitive member 1Y, the charging unit 2Y, the exposure unit 3Y, the developing unit 4Y, the cleaning unit 6Y, and the like are integrated as a process cartridge. On the other hand, it may be detachably mounted. Further, at least one of the charging unit 2Y, the exposure unit 3Y, the developing unit 4Y, the transfer or separator, and the cleaning unit 6Y is integrally supported together with the electrophotographic photosensitive member 1Y to form a process cartridge, and the process cartridge Is configured as a single image forming unit that can be attached to and detached from the apparatus main body A, and the single image forming unit is detachably attached to the apparatus main body A using a guide means such as a rail of the apparatus main body A. Also good.

  The housing 8 having the image forming units 10Y, 10M, 10C, and 10Bk and the endless belt-shaped intermediate transfer body unit 7 is configured to be drawable from the apparatus main body A by support rails 82L and 82R. In the housing 8, the image forming units 10Y, 10M, 10C, and 10Bk are arranged in a vertical row in the vertical direction. The endless belt-shaped intermediate transfer body unit 7 is disposed on the left side of the photoreceptors 1Y, 1M, 1C, and 1Bk in FIG. 4, and is an endless belt that can be rotated by winding rollers 71, 72, 73, and 74. Intermediate transfer body 70, primary transfer rollers 5Y, 5M, 5C, and 5Bk, and a cleaning unit 6b.

  Hereinafter, an image forming method using the image forming apparatus shown in FIG. 4 will be described. Each color image formed by the image forming units 10Y, 10M, 10C, and 10Bk is sequentially transferred onto a rotating endless belt-shaped intermediate transfer body 70 by primary transfer rollers 5Y, 5M, 5C, and 5Bk. Thereby, a synthesized color image is formed.

  A transfer material (for example, plain paper, transparent sheet, etc.) P accommodated in the paper feed cassette 20 is fed by a paper feed / conveying section 21 and passes through a plurality of intermediate rollers 22A, 22B, 22C, 22D and a registration roller 23. Then, it is conveyed to the secondary transfer roller 5b. In the secondary transfer roller 5b, the combined color image is secondarily transferred to the transfer material P, and thus the color image is transferred to the transfer material P all at once. When the combined color image is secondarily transferred onto the transfer material P, the endless belt-shaped intermediate transfer body 70 separates the transfer material P by curvature. The transfer material P is fixed by the fixing unit 24, sandwiched between the paper discharge rollers 25, and placed on the paper discharge tray 26 outside the apparatus. On the other hand, the toner (residual toner) adhering to the intermediate transfer member 70 is removed by the cleaning unit 6b.

  During image formation, the primary transfer roller 5Bk is always in contact with the surface of the electrophotographic photoreceptor 1Bk. On the other hand, the primary transfer rollers 5Y, 5M, and 5C are in contact with the surfaces of the corresponding electrophotographic photoreceptors 1Y, 1M, and 1C only during color image formation. The secondary transfer roller 5b contacts the surface of the endless belt-shaped intermediate transfer body 70 only when the transfer material P passes through the secondary transfer roller 5b and secondary transfer is performed.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to the following.
<Example 1>
An electrophotographic photosensitive member was produced according to the following method. First, the electroconductive support body by which the cutting process was given to the surface of the cylindrical aluminum support body was prepared.

(Formation of intermediate layer)
In a wet sand mill (a container is filled with alumina beads having a diameter of 0.5 mm), 1.0 part by mass of polyamide resin (binder resin, product number “X1010” manufactured by Daicel Evonik Co., Ltd.) and titanium dioxide particles ( 1.1 parts by mass (product number “SMT500SAS” manufactured by Teika Co., Ltd.) and 20 parts by mass of ethanol (solvent) were added and dispersed in a batch system for 10 hours. In this way, an intermediate layer forming liquid was obtained.

  A film made of the intermediate layer forming liquid was formed on the upper surface of the conductive support by a dip coating method, and then dried at 110 ° C. for 20 minutes. In this way, an intermediate layer having a thickness (thickness after drying) of 2 μm was formed on the upper surface of the conductive support.

(Formation of charge generation layer)
At least 2θ = 27.3 as determined by measuring an X-ray diffraction spectrum using a titanyl phthalocyanine pigment (charge generation material, characteristic X-ray (Cu—Kα ray)) in a wet sand mill of the same type as the wet sand mill used for forming the intermediate layer. 20 parts by mass of titanyl phthalocyanine pigment having a maximum diffraction peak at the position of °, 10 parts by mass of polyvinyl butyral resin (binder resin, product number “# 6000-C” manufactured by Denki Kagaku Kogyo Co., Ltd.), and t-butyl acetate ( Solvent) 700 parts by mass and 4-methoxy-4-methyl-2-pentanone (solvent) 300 parts by mass were added and dispersed for 10 hours. In this way, a charge generation layer forming liquid was obtained.

  A film made of the charge generation layer forming liquid was formed on the upper surface of the intermediate layer by a dip coating method and then dried. Thus, a charge generation layer having a thickness (thickness after drying) of 0.3 μm was formed on the upper surface of the intermediate layer.

(Formation of charge transport layer)
In a wet sand mill of the same type as the wet sand mill used for forming the intermediate layer and the like, 150 parts by mass of a compound (charge transport material) represented by the following chemical formula (18) and a polycarbonate resin (binder resin, manufactured by Mitsubishi Gas Chemical Co., Ltd.) 300 parts by mass of product number “Z300”), 6 parts by mass of antioxidant (product number “Irganox (registered trademark) 1010” manufactured by BASF Japan Ltd.), and a mixed solvent of toluene and tetrahydrofuran ((toluene): (tetrahydrofuran)) = 1: 9 (volume ratio)) 2000 parts by mass and silicone oil (additive, product number “KF-54” manufactured by Shin-Etsu Chemical Co., Ltd.) 1 part by mass are added, and the charge transport material and the binder resin are added. It was dissolved in a mixed solvent. In this way, a charge transport layer forming liquid was obtained.

  A film made of the charge transport layer forming liquid was formed on the upper surface of the charge generation layer by dip coating, and then dried at 110 ° C. for 60 minutes. Thus, a charge transport layer having a thickness (thickness after drying) of 20 μm was formed on the upper surface of the charge generation layer.

(Preparation of surface-treated organic particles)
In a glass beaker (capacity: ₂ L), put 15 g of a sodium silicate aqueous solution having a SiO ₂ concentration of 10% by mass (this sodium silicate aqueous solution contains 1.5 g of SiO ₂ ) and ₂ g of a 48% by mass sodium hydroxide aqueous solution. It was. The mixed solution in the glass beaker was diluted with ion-exchanged water so that the amount of liquid in the glass beaker was 900 g.

  To the diluted mixed solution, a dispersion liquid in which 10 g of organic particles (trade name “Eposter S6” manufactured by Nippon Shokubai Co., Ltd.) was dispersed in 100 g of methanol was added dropwise with stirring. It took 10 minutes to drop the dispersion. Further, the pH of the solution after completion of the dropwise addition of the dispersion was 10.

  The resulting solution was heated to 80 ° C., and 1% hydrochloric acid was added to adjust the pH of the solution to 8. The mixture was stirred at the same temperature for 120 minutes and then cooled to 25 ° C. An aqueous citric acid solution having a concentration of 10% by mass was further added to adjust the pH of the solution to 3.

The solution whose pH was adjusted to 3 was passed through an ultrafiltration module (manufactured by Asahi Kasei Chemicals Corporation, product number “Microza SLP-1053”) while replenishing the same amount of ion-exchanged water as the amount of filtration. T-Butylamine was added to the obtained filtrate to adjust the pH of the solution to 8, and then the solution was filtered again. The solid separated by filtration was washed to obtain a cake. The obtained cake was dried at 100 ° C. to obtain organic particles coated with a SiO ₂ film.

Concentrated hydrochloric acid was added to a mixed solvent (20 g) containing 18 g of methanol and 2 g of water to adjust the pH of the solution to 2-3. To this solution, 2.5 g of a silane coupling agent (3-methacryloxypropyl trimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., product number “KBM-503”)) was added, followed by stirring at room temperature for 1 hour. To this solution, 50 g of a methanol dispersion having an organic particle concentration of 10% by mass coated with a SiO ₂ film was added, followed by stirring at 40 ° C. for 2 hours. Thereafter, a saturated aqueous sodium hydrogen carbonate solution was added for neutralization. The resulting solution was filtered, and the solid separated by filtration was dried at 120 ° C. for 2 hours. In this way, surface-treated organic particles were obtained.

  2.5 g of the surface-treated organic particles and 47.5 g of methanol were mixed and stirred for 30 minutes using an ultrasonic homogenizer (manufactured by Nippon Seiki Seisakusho, product number “US-150A”). Thus, the dispersion liquid comprised by disperse | distributing the surface-treated organic particle in methanol was obtained. Methanol was added to 1 mL of this dispersion to dilute the dispersion 10 times. The diameter of the organic particles (median diameter of the organic particles) was confirmed using a dynamic light scattering particle size distribution measuring apparatus (manufactured by Horiba, Ltd., product number “LB-550”).

(Formation of surface layer)
85 parts by mass of inorganic particles (material: tin oxide, diameter: 20 nm), 25 parts by mass of surface-treated organic particles, and 100 parts by mass of the compound represented by the above chemical formula 2 (curable compound (monomer)) Then, 400 parts by mass of 2-butanol (solvent) and 40 parts by mass of THF (tetrahydrofuran) (solvent) were mixed under light shielding, and these were dispersed using a sand mill (dispersing machine) for 5 hours. 10 parts by mass of IRGACURE 819 (polymerization initiator) was added to the obtained dispersion, and the dispersion was stirred under light shielding to dissolve the polymerization initiator in the dispersion. In this way, a surface layer forming liquid was obtained.

  The liquid for surface layer formation was apply | coated to the upper surface of the electric charge transport layer using the circular slide hopper application | coating apparatus. The formed coating film was irradiated with light (ultraviolet rays) from a metal halide lamp for 1 minute. Thus, a surface layer having a thickness (thickness after drying) of 5.0 μm was formed on the upper surface of the charge transport layer.

<Example 2>
The amount of the sodium silicate aqueous solution having a SiO ₂ concentration of 10% by mass was changed to 20 g (the sodium silicate aqueous solution used in this example contains ₂ g of SiO ₂ ), and organic particles (trade name “manufactured by Nippon Shokubai Co., Ltd., trade name“ Surface-treated organic particles were prepared according to the same method as in Example 1 except that Eposter S12 ") was used. Using these organic particles, a surface layer was formed according to the same method as in Example 1. The amount of the surface-treated organic particles was as shown in Table 1.

<Example 3>
Instead of “15 g of sodium silicate aqueous solution having a SiO ₂ concentration of 10% by mass”, 6 g of titanium oxychloride aqueous solution having a concentration of 25% by mass (the titanium oxychloride aqueous solution used in this example contains 1.5 g of TiO ₂ ) The surface-treated organic particles were produced in the same manner as in Example 1 except that organic particles (trade name “Eposter S” manufactured by Nippon Shokubai Co., Ltd.) were used. Using these organic particles, a surface layer was formed according to the same method as in Example 1. The amount of the surface-treated organic particles was as shown in Table 1.

<Example 4>
The method was the same as in Example 1 except that the amount of the sodium silicate aqueous solution having a SiO ₂ concentration of 10% by mass was changed to 30 g (the aqueous sodium silicate solution used in this example contains 3 g of SiO ₂ ). Therefore, surface-treated organic particles were produced.

  Using the obtained organic particles, “inorganic particles (material: titanium oxide, diameter: 10 nm) 100 parts by mass” were used instead of “inorganic particles (material: tin oxide, diameter: 20 nm) 85 parts by mass”. A surface layer was formed in the same manner as in Example 1 except for the above. The amount of the surface-treated organic particles was as shown in Table 1.

<Example 5>
Instead of “15 g of sodium silicate aqueous solution having a SiO ₂ concentration of 10% by mass”, “8 g of titanium oxychloride aqueous solution having a concentration of 25% by mass (the titanium oxychloride aqueous solution used in this example contains ₂ g of TiO ₂ )” The surface-treated organic particles were produced in the same manner as in Example 1 except that organic particles (styrene-acrylic particles manufactured by Nippon Paint Co., Ltd.) were used. Using these organic particles, a surface layer was formed according to the same method as in Example 1.

<Example 6>
The amount of the sodium silicate aqueous solution having a SiO ₂ concentration of 10% by mass was changed to 5 g (the sodium silicate aqueous solution used in this example contains 0.5 g of SiO ₂ ). According to the method, surface-treated organic particles were produced.

  Using the obtained organic particles, “inorganic particles (material: titanium oxide, diameter: 10 nm) 100 parts by mass” were used instead of “inorganic particles (material: tin oxide, diameter: 20 nm) 85 parts by mass”. A surface layer was formed in the same manner as in Example 2 except for the above. The amount of the surface-treated organic particles was as shown in Table 1.

<Example 7>
According to the same method as in Example 5 except that the amount of the titanium oxychloride aqueous solution having a concentration of 25% by mass was changed to 4 g (the titanium oxychloride aqueous solution used in this example contains 1 g of TiO ₂ ). Surface-treated organic particles were prepared.

  Using the obtained organic particles, “inorganic particles (material: titanium oxide, diameter: 10 nm) 100 parts by mass” were used instead of “inorganic particles (material: tin oxide, diameter: 20 nm) 85 parts by mass”. A surface layer was formed in the same manner as in Example 5 except for the above.

<Comparative Example 1>
A surface layer was formed according to the same method as in Example 1 except that organic particles (manufactured by Nippon Shokubai Co., Ltd., trade name “Eposter S6”) were used instead of the surface-treated organic particles.

<Comparative Example 2>
A surface layer was formed according to the same method as in Example 1 except that PTFE particles were used instead of the surface-treated organic particles.

<Comparative Example 3>
According to the following method, organic particles whose surfaces were treated with the first organic compound were produced. Using these organic particles, a surface layer was formed according to the same method as in Example 1.

  Concentrated hydrochloric acid was added to a mixed solvent (20 g) containing 18 g of methanol and 2 g of water to adjust the pH of the solution to 2-3. To this solution, 2.5 g of a silane coupling agent (trade name “KBM-503”, manufactured by Shin-Etsu Chemical Co., Ltd.) was added, followed by stirring at room temperature for 1 hour. To this solution, 50 g of a methanol dispersion having a concentration of 10% by mass of organic particles (manufactured by Nippon Shokubai Co., Ltd., trade name “Eposter S6”) was added and stirred at 40 ° C. for 2 hours. Thereafter, a saturated aqueous sodium hydrogen carbonate solution was added for neutralization. The resulting solution was filtered, and the solid separated by filtration was dried at 120 ° C. for 2 hours. In this way, organic particles used in Comparative Example 3 were obtained.

<Evaluation>
(Evaluation of cleaning properties)
The electrophotographic photoreceptors of Examples 1 to 7 and Comparative Examples 1 to 3 were mounted as electrophotographic photoreceptors of an image forming apparatus (manufactured by Konica Minolta Business Solutions, Inc., product number “bizhub C6501”). In the image forming apparatus, a semiconductor laser having a wavelength of 780 nm was used as the exposure light source.

  A continuous paper passing test was performed in an environment of a temperature of 23 ° C. and a humidity of 50%. Specifically, 2000 sheets of A4 paper were arranged in the paper feed cassette so as to be “transversely fed”, and double-sided printing of a character image with an image ratio of 5% was continuously performed on 2000 sheets of A4 paper.

  After the continuous paper passing test, the number of deposits in a 2 cm × 4 cm region on the surface of the electrophotographic photosensitive member was visually measured. The results are shown in Table 1.

  In Table 1, “A1” is indicated when there is no toner slipping through and no deposit is found in the area, and when there is less than 10 deposits in the area without toner slipping, “A1” is indicated. B1 ". It can be said that the smaller the number of deposits on the surface of the electrophotographic photoconductor, the better the electrophotographic photoconductor is. The inventors of the present invention have determined that “A1” and “B1” in Table 1 are practical for use as an electrophotographic photosensitive member, and accordingly, in Examples 1 to 7 and Comparative Examples 1 to 3. In either case, an electrophotographic photoreceptor excellent in cleaning properties could be obtained.

(Evaluation of wear resistance)
First, the thickness of the surface layer of the electrophotographic photoreceptors of Examples 1 to 7 and Comparative Examples 1 to 3 was measured. Specifically, in a portion having a uniform thickness (by creating a film thickness profile, the thickness variation portion in the portion where the surface layer forming liquid is first applied and the portion where the surface layer forming liquid is applied last. Ten thickness measurement points were randomly selected in (excluding the thickness variation portion). Measure the thickness at the measurement point using an eddy current film thickness measuring instrument (Helmut Fischer, product number “EDDY560C”), and calculate the average thickness (thickness before the durability test). Calculated.

  Next, the electrophotographic photosensitive members of Examples 1 to 7 and Comparative Examples 1 to 3 were mounted as the electrophotographic photosensitive member of the image forming apparatus. In the image forming apparatus, a semiconductor laser having a wavelength of 780 nm was used as the exposure light source.

  Subsequently, a continuous paper passing test was performed in an environment of a temperature of 23 ° C. and a humidity of 50%. Specifically, 300,000 A4 sheets were placed in the paper feed cassette so as to be “transversely fed”, and double-sided printing of a character image with an image ratio of 5% was continuously performed on the 300,000 A4 sheets.

Thereafter, the electrophotographic photosensitive member was taken out from the image forming apparatus, and the thickness after the durability test was calculated according to the method for obtaining the thickness before the durability test. The amount of film thickness loss was determined using the following formula. The results are shown in Table 1.
(Amount of film thickness loss) = (Thickness before durability test) − (Thickness after durability test).

  In Table 1, when the film thickness wear amount is less than 1 μm, it is described as “A2”, and when the film thickness wear amount is 1 μm or more and less than 3 μm, it is described as “B2”, and the film thickness wear amount is 3 μm. If it is less than 4 μm, it is written as “C2”, and if the film thickness is 4 μm or more, it is written as “D2”. It can be said that the smaller the film thickness wear amount, the better the electrophotographic photoreceptor is in wear resistance. The inventors of the present invention have determined that practical use as an electrophotographic photosensitive member is possible when “A2”, “B2”, and “C2” in Table 1.

(Evaluation of fogging)
As the electrophotographic photosensitive member of the image forming apparatus, the electrophotographic photosensitive members of Examples 1 to 7 and Comparative Examples 1 to 3 were mounted. In the image forming apparatus, a semiconductor laser having a wavelength of 780 nm was used as the exposure light source.

  Under an environment of a temperature of 23 ° C. and a humidity of 50%, the difference between the surface potential of the electrophotographic photosensitive member and the surface potential of the developing portion (hereinafter referred to as “surface potential difference”) was set to 100V. A3 paper was placed in the paper feed cassette so as to be “vertically fed”, and a white image with an image ratio of 0% was printed on the A3 paper. After printing, the blackening ratio of the A3 paper (black area / white area) was determined. Thereafter, the surface potential difference was changed to 200 V and 300 V, and the blackening rate was determined according to the method described above. The results are shown in Table 1.

  In Table 1, when the surface potential difference is 100 V and the blackening rate is less than 0.1, “A3” is indicated, and when the surface potential difference is 200 V, the blackening rate is 0.1 or more and 0.00. When it is 2 or less, it is described as “B3”, and when the surface potential difference is 300 V, when the blackening rate is 0.2 or more, it is described as “C3”. As the surface potential difference is larger, the fog resistance is less likely to decrease, and as the surface potential difference is smaller, the fog resistance is likely to be decreased. A3 in Table 1 means that the blackening rate when a white image is printed in an environment in which the fog resistance is likely to decrease is less than 0.1, and thus the fog resistance is very excellent. On the other hand, C3 in Table 1 means that the fog resistance is reduced because the blackening rate when a white image is printed in an environment where the fog resistance is difficult to decrease is 0.2 or more. The inventors of the present invention have determined that practical use as an electrophotographic photosensitive member is possible when “A3” and “B3” in Table 1.

  <Results and discussion>

  In Table 1, “Eposter S”, “Eposter S6”, and “Eposter S12” are all melamine-formaldehyde particles.

In Table 1, “blending amount ^{* 11} ” indicates the blending amount (parts by mass) of the first metal oxide with respect to 100 parts by mass of the organic particles. In “addition amount ^{* 12} ”, in Examples 1 to 7, the blending amount (parts by mass) of the surface-treated organic particles with respect to 100 parts by mass of the curable compound is described, and in Comparative Examples 1 and 2, the curable compound is 100 parts by mass. The amount (parts by mass) of the organic particles relative to the part is described. In Comparative Example 3, the amount (parts by mass) of the organic particles whose surface is treated with the first organic compound with respect to 100 parts by mass of the curable compound is described.

  In any of Examples 1 to 7 and Comparative Examples 1 to 3, the cleaning property was good. It is considered that the cleaning property could be improved because the surface layer contains organic particles.

  In Examples 1 to 7, the wear resistance of the surface layer was improved as compared with Comparative Example 2. The following can be considered as the reason. In Comparative Example 2, the surface layer does not include the surface-treated organic particles. Therefore, the organic particles in the surface layer do not contribute to the curing reaction of the curable compound (monomer), and thus the strength of the surface layer is reduced. As a result, contact between the surface layer and the blade caused organic particles to be detached from the surface layer.

  In Examples 1-7, compared with Comparative Example 1 and Comparative Example 3, fog resistance could be increased. The following can be considered as the reason. In Comparative Example 1, the surface layer does not contain surface-treated organic particles. Therefore, the exposure of organic particles from the surface layer could not be prevented, and therefore, the organic particles exposed from the surface layer and the toner spikes were rubbed, resulting in a decrease in the surface potential of the electrophotographic photosensitive member. .

  In Comparative Example 3, an inorganic film is not provided on the surface of the organic particles. For this reason, a reaction point with the first organic compound cannot be secured on the surface of the organic particle, and therefore, the first organic compound is hardly bonded to the surface of the organic particle. As a result, the surface potential of the electrophotographic photosensitive member was lowered for the same reason as in Comparative Example 1.

  From the above, it was found that the surface layer preferably contains surface-treated organic particles in order to improve the wear resistance of the surface layer and enhance the fog resistance while improving the cleaning property.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  100 electrophotographic photoreceptor, 101 conductive support, 102 intermediate layer, 103 photosensitive layer, 104 charge generation layer, 105 charge transport layer, 106 surface layer, 201 organic particles, 202, 204, 304 surface, 203 inorganic film, 205 Organic particles coated with an inorganic film, 207 first organic compound, 207a first inorganic side reactive group, 207b first organic side reactive group, 210 surface-treated organic particles, 303 inorganic particles, 307 second organic compound, 307a Second inorganic side reactive group, 307b Second organic side reactive group, 310 Surface-treated inorganic particles.

Claims (7)

An electrophotographic photosensitive member comprising a conductive support, and a photosensitive layer and a surface layer sequentially provided on the conductive support,
The surface layer is composed of a resin and includes organic particles having a diameter of 100 nm to 1500 nm.
At least part of the surface of the organic particles is provided with an inorganic film made of a first metal oxide,
The inorganic film is bonded to the resin by a component derived from a first organic compound including a first inorganic side reactive group bonded to the surface of the inorganic film and a first organic side reactive group bonded to the resin. Electrophotographic photosensitive member.   The electrophotographic photosensitive member according to claim 1, wherein the organic particles are made of a compound having a melamine structure. The electrophotographic photosensitive member according to claim 1, wherein the first metal oxide is SiO ₂ or TiO ₂ .   The electrophotographic photosensitive member according to claim 1, wherein the first organic side reactive group is an acryloyl group or a methacryloyl group. The surface layer further includes inorganic particles made of a second metal oxide,
The inorganic particles are bonded to the resin by a component derived from a second organic compound including a second inorganic side reactive group bonded to the surface of the inorganic particle and a second organic side reactive group bonded to the resin. Electrophotographic photosensitive member. The electrophotographic photosensitive member according to claim 1,
A charging unit for charging the surface of the electrophotographic photosensitive member;
An exposure part for forming an electrostatic latent image on the surface of the electrophotographic photosensitive member;
An electrophotographic image forming apparatus comprising: a developing unit that develops the electrostatic latent image with toner to form a toner image. Removably attached to the electrophotographic image forming apparatus,
The electrophotographic photosensitive member according to claim 1,
A charging unit for charging the surface of the electrophotographic photosensitive member;
An exposure part for forming an electrostatic latent image on the surface of the electrophotographic photosensitive member;
A process cartridge comprising: a developing unit that develops the electrostatic latent image with toner to form a toner image.

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