JP7392299B2 - Dispersant-adhered polytetrafluoroethylene particles, compositions, layered products, electrophotographic photoreceptors, process cartridges, and image forming devices - Google Patents

Description

The present invention relates to dispersant-adhered polytetrafluoroethylene particles, compositions, layered products, electrophotographic photoreceptors, process cartridges, and image forming apparatuses.

Polytetrafluoroethylene particles are widely used as, for example, lubricants.

For example, Patent Document 1 discloses "an electrophotographic photoreceptor containing fluorine atom-containing resin particles in a photosensitive layer." Patent Document 1 discloses polytetrafluoroethylene particles as fluorine atom-containing resin particles.

On the other hand, Patent Document 2 states that "a photosensitive layer containing a surfactant and a binder resin,
The content of the surfactant is 0.10 parts by mass or more and 3.00 parts by mass or less with respect to 100.00 parts by mass of the binder resin, and the hydrophobic group of the surfactant is a perfluoroalkyl group. An electrophotographic photoreceptor, wherein the surfactant has nonionic properties. ' has been disclosed.

Japanese Patent Application Publication No. 2009-104145 JP2017-090566A

The polytetrafluoroethylene particles are used in combination with a dispersant having a fluorine atom (hereinafter also referred to as a "fluorine-containing dispersant"), and components such as a dispersion medium and powder. However, when the state of the components to be mixed (for example, changes in the evaporation of the dispersion medium, melting of the powder, etc.) occurs, the dispersibility of the polytetrafluoroethylene particles tends to decrease.

Therefore, an object of the present invention is to reduce the amount of perfluorooctanoic acid (hereinafter also referred to as "PFOA") contained in polytetrafluoroethylene particles (hereinafter also referred to as "PTFE particles") as compared to cases where the content exceeds 25 ppb. An object of the present invention is to provide dispersant-adhered polytetrafluoroethylene particles that maintain a highly dispersed state even if the state of the components changes.

The above problem is solved by the following means.

<1>
Dispersant-attached polytetrafluoroethylene particles having a dispersant having a fluorine atom attached to the surface and having a perfluorooctanoic acid content of 0 ppb or more and 25 ppb or less based on the polytetrafluoroethylene particles.
<2>
The dispersant-adhered polytetrafluoroethylene particles according to <1>, which have an average particle size of 0.2 μm or more and 4.5 μm or less.
<3>
The dispersant-attached polytetrafluoroethylene particles according to <1> or <2>, wherein the dispersant having a fluorine atom is a polymer obtained by homopolymerizing or copolymerizing a polymerizable compound having a fluorinated alkyl group.
<4>
The polymer obtained by homopolymerizing or copolymerizing the above polymerizable compound having a fluorinated alkyl group is a fluorinated alkyl group-containing polymer having a structural unit represented by the following general formula (FA), or a fluorinated alkyl group-containing polymer having a structural unit represented by the following general formula (FA). The dispersant-adhered polytetrafluoroethylene particles according to <3>, which is a fluorinated alkyl group-containing polymer having the structural unit shown below and the structural unit shown by the following general formula (FB).



(In the general formulas (FA) and (FB), R ^F1 , R ^F2 , R ^F3 and R ^F4 each independently represent a hydrogen atom or an alkyl group. X ^F1 is an alkylene chain, a halogen-substituted alkylene chain, -S-, -O-, -NH-, or a single bond.Y ^F1 represents an alkylene chain, a halogen-substituted alkylene chain, -(C _fx H _2fx-1 (OH))-, or a single bond.Q ^F1 represents -O- or -NH-.fl, fm and fn each independently represent an integer of 1 or more.fp, fq, fr and fs each independently represent 0 or 1 or more Represents an integer. ft represents an integer between 1 and 7. fx represents an integer between 1 and more.)
<5>
The dispersant according to any one of <1> to <4>, wherein the content of the dispersant having a fluorine atom is 0.5% by mass or more and 10% by mass or less based on the polytetrafluoroethylene particles. Attached polytetrafluoroethylene particles.
<6>
The dispersant-attached polytetrafluoroethylene particles according to <5>, wherein the content of the dispersant having a fluorine atom is 1% by mass or more and 7% by mass or less based on the polytetrafluoroethylene particles.
<7>
Contains polytetrafluoroethylene particles and a dispersant having a fluorine atom,
A composition having a perfluorooctanoic acid content of 0 ppb or more and 25 ppb or less based on the polytetrafluoroethylene particles.
<8>
The composition according to <7>, wherein the polytetrafluoroethylene particles have an average particle size of 0.2 μm or more and 4.5 μm or less.
<9>
The composition according to <7> or <8>, which is liquid or solid.
<10>
Contains polytetrafluoroethylene particles and a dispersant having a fluorine atom,
A layered material having a perfluorooctanoic acid content of 0 ppb or more and 25 ppb or less based on the polytetrafluoroethylene particles.
<11>
The layered material according to <10>, wherein the polytetrafluoroethylene particles have an average particle size of 0.2 μm or more and 4.5 μm or less.
<12>
comprising an electrically conductive substrate and a photosensitive layer provided on the electrically conductive substrate,
An electrophotographic photoreceptor, wherein the outermost surface layer is a layer made of the layered material according to <10> or <11>.
<13>
The electrophotographic photoreceptor according to <12>, wherein the outermost surface layer is a surface protective layer having a crosslinked structure.
<14>
comprising the electrophotographic photoreceptor according to <12> or <13>,
A process cartridge that can be attached to and removed from an image forming apparatus.
<15>
The electrophotographic photoreceptor according to <12> or <13>,
Charging means for charging the surface of the electrophotographic photoreceptor;
an electrostatic latent image forming means for forming an electrostatic latent image on the charged surface of the electrophotographic photoreceptor;
a developing means for developing the electrostatic latent image formed on the surface of the electrophotographic photoreceptor to form a toner image with a developer containing toner;
a transfer means for transferring the toner image onto the surface of a recording medium;
An image forming apparatus comprising:

According to the invention according to <1>, <2>, <3>, <4>, <5>, or <6>, compared to the case where the PFOA content is more than 25 ppb with respect to the PTFE particles, Dispersant-adhered PTFE particles are provided that maintain a highly dispersed state even if the state of the components changes.
According to the invention according to <7>, <8>, or <9>, compared to the case where the PFOA content exceeds 25 ppb with respect to the PTFE particles, even if the state of the component mixed with the PTFE particles changes. , a composition in which the dispersion state of PTFE particles is highly maintained is provided.
According to the invention according to <10>, <11>, <12>, <13>, <14> or <15>, the PFOA content of the PTFE particles is greater than 25 ppb compared to the case where the PFOA content is more than 25 ppb relative to the PTFE particles. A highly dispersed layered material, an electrophotographic photoreceptor having an outermost surface layer made of the layered material, a process cartridge including the electrophotographic photoreceptor, or an image forming apparatus including the electrophotographic photoreceptor are provided.

FIG. 1 is a schematic cross-sectional view showing an example of the layer structure of the electrophotographic photoreceptor of the present embodiment. 1 is a schematic configuration diagram showing an example of an image forming apparatus according to an embodiment. FIG. 3 is a schematic configuration diagram showing another example of the image forming apparatus according to the present embodiment.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment which is an example of this invention is described in detail.

(Dispersant-adhered polytetrafluoroethylene particles)
The dispersant-attached polytetrafluoroethylene particles (dispersant-attached PTFE particles) according to the present embodiment are PTFE particles to which a dispersant having a fluorine atom (fluorine-containing dispersant) is attached.
The dispersant-attached PTFE particles according to the present embodiment have a perfluorooctanoic acid (PFOA) content of 0 ppb or more and 25 ppb or less based on the polytetrafluoroethylene particles (PTFE particles).

Due to the above structure, the dispersant-adhered PTFE particles according to the present embodiment can maintain a dispersed state even if the state of the components to be mixed changes. The reason is assumed to be as follows.

Generally, PTFE particles are used in combination with a fluorine-containing dispersant, for example, components such as a dispersion medium and powder. However, when the state of the components to be mixed (for example, changes in the evaporation of the dispersion medium, melting of the powder, etc.) occurs, the dispersibility of the polytetrafluoroethylene particles tends to decrease.

Specifically, for example, a layered material containing PTFE particles is formed by using a liquid composition (e.g., layer-forming coating liquid, etc.) containing a resin and a dispersion medium together with PTFE particles and a fluorine-containing dispersant. In this case, the dispersion medium is dried during the process of forming the layered material. Then, in the process of drying (that is, evaporating) the dispersion medium, the dispersibility of the PTFE particles decreases and aggregation of the PTFE particles may occur.
For example, when forming a layered product containing PTFE particles by using a solid composition containing resin particles (such as a powder coating) together with PTFE particles and a fluorine-containing dispersant, the process of forming the layered product This causes the resin to melt. Then, in the process of melting the resin, the dispersibility of the PTFE particles decreases, and agglomeration of the PTFE particles may occur.

As a result, a layered material is formed in which the PTFE particles are poorly dispersed. The reason for this is as follows.
PTFE particles often contain PFOA because PFOA is used or produced as a by-product during the manufacturing process.
When PFOA exists, in the state of the composition, the PTFE particles are highly dispersible due to the fluorine-containing dispersant, but when the state of the components to be mixed changes, the adhesion state of the fluorine-containing dispersant to the PTFE particles changes. Change. Specifically, it is thought that a part of the fluorine-containing dispersant is separated from the PTFE particles due to PFOA. Therefore, the dispersibility of the PTFE particles decreases and aggregation of the PTFE particles occurs.

Therefore, the dispersant-attached PTFE particles according to the present embodiment have a PFOA content of 0 ppb or more and 25 ppb or less relative to the PTFE particles. That is, it does not contain PFOA, or even if it does contain it, the content is suppressed. This suppresses "changes in the state of adhesion of the fluorine-containing dispersant to the PTFE particles" that occurs when the state of the components to be mixed changes due to PFOA.

From the above, it is presumed that the dispersant-adhered PTFE particles according to the present embodiment have a high ability to maintain the dispersed state even if the state of the components to be mixed changes.

The details of the dispersant-attached PTFE particles according to this embodiment will be described below.

The PFOA content is 0 ppb or more and 25 ppb or less relative to the PTFE particles, but from the viewpoint of improving maintenance of the dispersion state, it is preferably 0.01 ppb or more and 20 ppb or less, and more preferably 0.1 ppb or more and 15 ppb or less. Note that "ppb" is based on mass.
Methods for reducing the PFOA content include pure water, alkaline water, alcohols (methanol, ethanol, isopropanol, etc.), ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.), esters (ethyl acetate, etc.), and other Examples include a method in which the PTFE particles are thoroughly washed with a general organic solvent (toluene, tetrahydrofuran, etc.). Although the cleaning may be performed at room temperature, it can be efficiently reduced by performing the cleaning under heating.

PFOA content is a value measured by the following method.
-Sample pretreatment-
In the case of a layered product containing dispersant-attached PTFE particles, the layered product is immersed in a solvent (e.g., tetrahydrofuran), and after dissolving everything other than the PTFE particles and substances insoluble in the solvent in the solvent (e.g., tetrahydrofuran), it is dropped into pure water. and filter out the precipitate. The solution containing PFOA obtained at that time is collected. Furthermore, after dissolving the insoluble matter obtained by filtration in a solvent, it is dropped into pure water and the precipitate is filtered off. The operation of collecting the PFOA-containing solution obtained at that time was repeated five times, and the aqueous solution collected in all the operations was used as the pretreated aqueous solution.
In the case of a composition containing dispersant-attached PTFE particles, the composition is subjected to the same treatment as in the case of a layered material to obtain a pretreated aqueous solution.
In the case of dispersant-attached PTFE particles, the same treatment as in the case of the layered material is performed on the dispersant-attached PTFE particles to obtain a pretreated aqueous solution.

-measurement-
Analysis of perfluorooctane sulfonic acid (PFOS) perfluorooctane perfluorooctanoic acid (PFOA) in environmental water, sediment, and living organisms Iwate Prefecture Environment Prepare and measure the sample solution according to the method described in the Health Research Center.

The average particle size of the PTFE particles (average particle size of the PTFE particles to which the dispersant is attached) is not particularly limited, but is preferably 0.2 μm or more and 4.5 μm or less, more preferably 0.2 μm or more and 4 μm or less. PTFE particles with an average particle diameter of 0.2 μm or more and 4.5 μm or less tend to contain a large amount of PFOA. Therefore, the dispersion state of PTFE particles having an average particle diameter of 0.2 μm or more and 4.5 μm or less tends to deteriorate particularly when the state of the components to be mixed changes. However, by suppressing the PFOA content within the above range, even if the PTFE particles have an average particle diameter of 0.2 μm or more and 4.5 μm or less, the maintenance of the dispersed state is improved even if the state of the components to be mixed changes.

The average particle size of PTFE particles is a value measured by the following method.
Observe with a SEM (scanning electron microscope) at a magnification of, for example, 5000 times or more, measure the maximum diameter of the fluororesin particles (secondary particles aggregated by primary particles), and calculate the average value of 50 particles. The average particle size of the particles. Note that a JSM-6700F manufactured by JEOL Ltd. is used as the SEM, and a secondary electron image is observed at an accelerating voltage of 5 kV.

Examples of the fluorine-containing dispersant include a polymer obtained by homopolymerizing or copolymerizing a polymerizable compound having a fluorinated alkyl group (hereinafter also referred to as a "fluorinated alkyl group-containing polymer").

Specifically, examples of fluorine-containing dispersants include homopolymers of (meth)acrylates having fluorinated alkyl groups, random or block copolymers of (meth)acrylates having fluorinated alkyl groups, and monomers having no fluorine atoms. Examples include merging. Note that (meth)acrylate means both acrylate and methacrylate.
Examples of the (meth)acrylate having a fluorinated alkyl group include 2,2,2-trifluoroethyl (meth)acrylate and 2,2,3,3,3-pentafluoropropyl (meth)acrylate.
Examples of monomers that do not have a fluorine atom include (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, isooctyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, and isobornyl. (meth)acrylate, cyclohexyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, methoxytriethylene glycol (meth)acrylate, 2-ethoxyethyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, benzyl (meth)acrylate Acrylate, ethyl carbitol (meth)acrylate, phenoxyethyl (meth)acrylate, 2-hydroxy (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, methoxypolyethylene glycol (meth)acrylate , methoxypolyethylene glycol (meth)acrylate, phenoxypolyethylene glycol (meth)acrylate, phenoxypolyethylene glycol (meth)acrylate, hydroxyethyl o-phenylphenol (meth)acrylate, and o-phenylphenol glycidyl ether (meth)acrylate.

In addition, specific examples of fluorine-containing dispersants include block or branch polymers disclosed in US Pat. No. 5,637,142, Japanese Patent No. 4,251,662, and the like. Further, specific examples of the fluorine-containing dispersant include fluorine-based surfactants.

Among these, as the fluorine-containing dispersant, a fluorinated alkyl group-containing polymer having a structural unit represented by the following general formula (FA) is preferable, and a polymer containing a fluorinated alkyl group having a structural unit represented by the following general formula (FA) and the following general formula A fluorinated alkyl group-containing polymer having a structural unit represented by (FB) is more preferred.

Hereinafter, a fluorinated alkyl group-containing polymer having a structural unit represented by the following general formula (FA) and a structural unit represented by the following general formula (FB) will be described.

In general formulas (FA) and (FB), R ^F1 , R ^F2 , R ^F3 and R ^F4 each independently represent a hydrogen atom or an alkyl group.
X ^F1 represents an alkylene chain, a halogen-substituted alkylene chain, -S-, -O-, -NH-, or a single bond.
Y ^F1 represents an alkylene chain, a halogen-substituted alkylene chain, -(C _fx H _2fx-1 (OH))-, or a single bond.
Q ^F1 represents -O- or -NH-.
fl, fm and fn each independently represent an integer of 1 or more.
fp, fq, fr, and fs each independently represent an integer of 0 or 1 or more.
ft represents an integer from 1 to 7.
fx represents an integer of 1 or more.

In the general formulas (FA) and (FB), the groups representing R ^F1 , R ^F2 , R ^F3 and R ^F4 are preferably a hydrogen atom, a methyl group, an ethyl group, a propyl group, etc., and a hydrogen atom or a methyl group is more preferred. Preferably, methyl group is more preferable.

In general formulas (FA) and (FB), the alkylene chain (unsubstituted alkylene chain, halogen-substituted alkylene chain) representing X ^F1 and Y ^F1 is a linear or branched alkylene chain having 1 to 10 carbon atoms. is preferred.
fx in -(C _fx H _2fx-1 (OH))-, which represents Y ^F1 , preferably represents an integer of 1 or more and 10 or less.
It is preferable that fp, fq, fr, and fs each independently represent 0 or an integer from 1 to 10.
For example, fn is preferably 1 or more and 60 or less.

Here, in the fluorine-containing dispersant, the ratio of the structural unit represented by the general formula (FA) to the structural unit represented by the general formula (FB), that is, fl:fm, is from 1:9 to 9:1. A range of 3:7 to 7:3 is more preferred.

In addition to the structural unit represented by the general formula (FA) and the structural unit represented by the general formula (FB), the fluorine-containing dispersant may further have a structural unit represented by the general formula (FC). . The content ratio of the structural units represented by the general formula (FC) is the sum of the structural units represented by the general formulas (FA) and (FB), that is, the ratio of fl+fm (fl+fm:fz), from 10:0 to 7: A range of up to 3 is preferred, and a range of 9:1 to 7:3 is more preferred.

In the general formula (FC), R ^F5 and R ^F6 each independently represent a hydrogen atom or an alkyl group. fz represents an integer of 1 or more.

In the general formula (FC), the groups representing R ^F5 and R ^F6 are preferably a hydrogen atom, a methyl group, an ethyl group, a propyl group, etc., more preferably a hydrogen atom or a methyl group, and still more preferably a methyl group.

Commercially available fluorine-containing dispersants include, for example, GF300, GF400 (manufactured by Toagosei Co., Ltd.), Surflon series (manufactured by AGC Seimikekical Co., Ltd.), Ftergent series (manufactured by Neos Co., Ltd.), PF series (manufactured by Kitamura Chemical Co., Ltd.), Examples include the Megafac series (manufactured by DIC) and the FC series (manufactured by 3M).

The weight average molecular weight of the fluorine-containing dispersant is, for example, preferably 2,000 or more and 250,000 or less, more preferably 3,000 or more and 150,000 or less, and even more preferably 50,000 or more and 100,000 or less.
The weight average molecular weight of the fluorine-containing dispersant is a value measured by gel permeation chromatography (GPC). Molecular weight measurement by GPC is performed using, for example, Tosoh GPC/HLC-8120 as a measuring device, Tosoh column TSKgel GMHHR-M + TSKgel GMHHR-M (7.8 mm I.D. 30 cm), and chloroform solvent. Calculation is made from this measurement result using a molecular weight calibration curve prepared using a monodisperse polystyrene standard sample.

The content of the fluorine-containing dispersant is, for example, preferably from 0.5% by mass to 10% by mass, more preferably from 1% by mass to 7% by mass, based on the PTFE particles.
Note that the fluorine-containing dispersants may be used alone or in combination of two or more.

The method for manufacturing the dispersant-attached PTFE particles according to this embodiment includes:
1) A method of preparing a dispersion of PTFE particles by blending PTFE particles and a fluorine-containing dispersant into a dispersion medium, and then removing the dispersion medium from the dispersion.
2) A method of adhering the fluorine-containing dispersant to the PTFE particles by mixing the PTFE particles and a fluorine-containing dispersant using a dry powder mixer. 3) Dropping the fluorine-containing dispersant dissolved in a solvent while stirring the PTFE particles. Examples include a method of removing the post-solvent.

(Composition)
The composition according to this embodiment contains PTFE particles and a fluorine-containing dispersant. The composition according to the present embodiment has a PFOA content of 0 ppb or more and 25 ppb or less relative to the PTFE particles.
That is, the composition according to this embodiment includes the dispersant-attached PTFE particles according to this embodiment. Therefore, the composition according to the present embodiment is a composition in which the dispersion state of the PTFE particles is highly maintained even if the state of the components mixed with the PTFE particles changes.

However, the composition according to the present embodiment may be a composition prepared by mixing previously prepared dispersant-attached PTFE particles with other components (for example, a dispersion medium, resin particles other than PTFE particles, etc.). However, it may be a composition in which PTFE particles, a fluorine-containing dispersant, and other components (for example, a dispersion medium, resin particles other than PTFE particles, etc.) are individually mixed.

The composition according to this embodiment may be either a liquid composition or a solid composition.
Examples of the liquid composition include a PTFE particle dispersion containing PTFE particles, a fluorine-containing dispersant, and a dispersion medium, and a layered material-forming coating liquid in which a resin is blended with a PTFE particle dispersion.
Examples of solid compositions include compositions containing dispersant-attached PTFE particles and resin particles (eg, toner particles, powder coating particles, etc.).

(layered material)
The layered material according to this embodiment contains PTFE particles and a fluorine-containing dispersant. The composition according to the present embodiment has a PFOA content of 0 ppb or more and 25 ppb or less relative to the PTFE particles.
That is, the layered material according to this embodiment includes PTFE particles to which a dispersant is attached. Specifically, the layered material according to this embodiment is a layer formed from the composition according to this embodiment.
Therefore, the layered material according to this embodiment is a layered material in which the PTFE particles are highly dispersed. The layered material according to the present embodiment is a layered material having excellent surface properties such as lubricity and hydrophobicity (water repellency) (particularly a layered material with less uneven surface properties).

Examples of the layered material according to this embodiment include the outermost layer of an electrophotographic photoreceptor, a toner image, a powder coating layer, and a sliding layer.

In addition, in the layered material according to this embodiment, from the viewpoint of exhibiting the above-mentioned surface properties, the content of PTFE particles is preferably 0.1% by mass or more and 40% by mass or less, and 1% by mass or more and 30% by mass or less based on the layered material. It is more preferably less than % by mass.

(electrophotographic photoreceptor)
The electrophotographic photoreceptor (hereinafter also referred to as "photoreceptor") according to the present embodiment has a conductive base and a photosensitive layer provided on the conductive base, and the outermost layer is the one according to the present embodiment. This is a layer made of a layered material related to.
Examples of the outermost layer made of this layered material include a charge transport layer of a laminated photosensitive layer, a single layer photosensitive layer, and a surface protective layer.
The photoreceptor according to this embodiment has a layer made of the layered material according to this embodiment as the outermost layer, and therefore has high wear resistance. In particular, in a photoreceptor, if the dispersibility of PTFE particles contained in the outermost layer is low, image defects (specifically, streak-like image unevenness) tend to occur. However, in the photoreceptor according to the present embodiment, since the PTFE particles are included in the outermost layer in a highly dispersible state, the above-mentioned image defects are suppressed.

The electrophotographic photoreceptor according to this embodiment will be described below with reference to the drawings.
The electrophotographic photoreceptor 7 shown in FIG. 1 has, for example, a structure in which a subbing layer 1, a charge generation layer 2, and a charge transport layer 3 are laminated in this order on a conductive support 4. can be mentioned. The charge generation layer 2 and the charge transport layer 3 constitute the photosensitive layer 5.

Note that the electrophotographic photoreceptor 7 may have a layered structure in which the subbing layer 1 is not provided.
Further, the electrophotographic photoreceptor 7 may be a photoreceptor having a single-layer type photoreceptor layer in which the functions of the charge generation layer 2 and the charge transport layer 3 are integrated. In the case of a photoreceptor having a single-layer type photosensitive layer, the single-layer type photosensitive layer constitutes the outermost surface layer.
Further, the electrophotographic photoreceptor 7 may be a photoreceptor having a surface protective layer on the charge transport layer 3 or on the single-layer photosensitive layer. In the case of a photoreceptor having a surface protective layer, the surface protective layer constitutes the outermost layer.

Each layer of the electrophotographic photoreceptor according to this embodiment will be described in detail below. Note that the description will be omitted with reference numerals.

(Conductive substrate)
Examples of the conductive substrate include metal plates, metal drums, and metal belts containing metals (aluminum, copper, zinc, chromium, nickel, molybdenum, vanadium, indium, gold, platinum, etc.) or alloys (stainless steel, etc.). can be mentioned. Examples of conductive substrates include paper, resin films, belts, etc. coated with, vapor-deposited, or laminated with conductive compounds (e.g., conductive polymers, indium oxide, etc.), metals (e.g., aluminum, palladium, gold, etc.), or alloys. can also be mentioned. Here, "conductivity" means that the volume resistivity is less than 10 ¹³ Ωcm.

When the electrophotographic photoreceptor is used in a laser printer, the surface of the conductive substrate has a centerline average roughness Ra of 0.04 μm or more and 0.5 μm for the purpose of suppressing interference fringes that occur when irradiated with laser light. It is preferable that the surface be roughened. Note that when incoherent light is used as a light source, surface roughening to prevent interference fringes is not particularly necessary, but it is suitable for longer life because it suppresses the occurrence of defects due to unevenness on the surface of the conductive substrate.

Examples of surface roughening methods include wet honing, which is performed by suspending an abrasive in water and spraying it on the conductive substrate, and centerless grinding, which is performed by pressing the conductive substrate against a rotating grindstone and grinding it continuously. , anodizing treatment, etc.

The surface roughening method involves dispersing conductive or semiconductive powder in a resin to form a layer on the surface of the conductive substrate, without roughening the surface of the conductive substrate. Another example is a method of roughening the surface using particles dispersed in the layer.

Surface roughening treatment by anodic oxidation is a method of forming an oxide film on the surface of a conductive substrate by anodic oxidation in an electrolyte solution using a metal (for example, aluminum) conductive substrate as an anode. Examples of the electrolyte solution include sulfuric acid solution and oxalic acid solution. However, the porous anodic oxide film formed by anodic oxidation is chemically active as it is, is easily contaminated, and has large resistance fluctuations depending on the environment. Therefore, for a porous anodic oxide film, the micropores of the oxide film are blocked by volume expansion caused by a hydration reaction with pressurized steam or boiling water (metal salts such as nickel may be added) to achieve more stable hydrated oxidation. It is preferable to perform a sealing process to convert the material into a material.

The thickness of the anodic oxide film is preferably, for example, 0.3 μm or more and 15 μm or less. When the film thickness is within the above range, barrier properties against injection tend to be exhibited, and increases in residual potential due to repeated use tend to be suppressed.

The conductive substrate may be treated with an acidic treatment liquid or treated with boehmite.
The treatment with the acidic treatment liquid is carried out, for example, as follows. First, an acidic treatment solution containing phosphoric acid, chromic acid, and hydrofluoric acid is prepared. The blending ratio of phosphoric acid, chromic acid, and hydrofluoric acid in the acidic treatment solution is, for example, phosphoric acid in the range of 10% by mass to 11% by mass, chromic acid in the range of 3% to 5% by mass, and hydrofluoric acid in the range of 3% to 5% by mass. The range is 0.5% by mass or more and 2% by mass or less, and the overall concentration of these acids is preferably in the range of 13.5% by mass or more and 18% by mass or less. The treatment temperature is preferably, for example, 42°C or higher and 48°C or lower. The thickness of the coating is preferably 0.3 μm or more and 15 μm or less.

The boehmite treatment is performed, for example, by immersion in pure water at 90° C. or higher and 100° C. or lower for 5 minutes to 60 minutes, or by contacting with heated steam at 90° C. or higher and 120° C. or lower for 5 minutes to 60 minutes. The thickness of the coating is preferably 0.1 μm or more and 5 μm or less. This can be further anodized using an electrolyte solution with low film solubility, such as adipic acid, boric acid, borate, phosphate, phthalate, maleate, benzoate, tartrate, or citrate. good.

(subbing layer)
The subbing layer is, for example, a layer containing inorganic particles and a binder resin.

Examples of the inorganic particles include inorganic particles having a powder resistance (volume resistivity) of 10 ² Ωcm or more and 10 ¹¹ Ωcm or less.
Among these, as the inorganic particles having the above-mentioned resistance value, metal oxide particles such as tin oxide particles, titanium oxide particles, zinc oxide particles, and zirconium oxide particles are preferable, and zinc oxide particles are particularly preferable.

The specific surface area of the inorganic particles measured by the BET method is preferably 10 m ² /g or more, for example.
The volume average particle diameter of the inorganic particles is, for example, 50 nm or more and 2000 nm or less (preferably 60 nm or more and 1000 nm or less).

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

The inorganic particles may be surface-treated. Two or more types of inorganic particles with different surface treatments or different particle sizes may be used as a mixture.

Examples of the surface treatment agent include silane coupling agents, titanate coupling agents, aluminum coupling agents, and surfactants. In particular, silane coupling agents are preferred, and silane coupling agents having an amino group are more preferred.

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

Two or more types of silane coupling agents may be used in combination. For example, a silane coupling agent having an amino group and another silane coupling agent may be used together. Examples of other silane coupling agents include vinyltrimethoxysilane, 3-methacryloxypropyl-tris(2-methoxyethoxy)silane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and 3-glyoxypropyl-tris(2-methoxyethoxy)silane. Sidoxypropyltrimethoxysilane, vinyltriacetoxysilane, 3-mercaptopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-( Examples include, but are not limited to, aminoethyl)-3-aminopropylmethyldimethoxysilane, N,N-bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane, and 3-chloropropyltrimethoxysilane. It's not a thing.

The surface treatment method using the surface treatment agent may be any known method, and may be either a dry method or a wet method.

The amount of the surface treatment agent to be treated is preferably, for example, 0.5% by mass or more and 10% by mass or less based on the inorganic particles.

Here, it is preferable for the undercoat layer to contain an electron-accepting compound (acceptor compound) together with inorganic particles, from the viewpoint of improving long-term stability of electrical properties and carrier blocking properties.

Examples of electron-accepting compounds include quinone compounds such as chloranil and bromoanil; tetracyanoquinodimethane compounds; 2,4,7-trinitrofluorenone, 2,4,5,7-tetranitro-9-fluorenone, etc. Fluorenone compound; 2-(4-biphenyl)-5-(4-t-butylphenyl)-1,3,4-oxadiazole, 2,5-bis(4-naphthyl)-1,3,4- Oxadiazole compounds such as oxadiazole, 2,5-bis(4-diethylaminophenyl)-1,3,4oxadiazole; xanthone compounds; thiophene compounds; 3,3',5,5'tetra- Examples include electron transporting substances such as diphenoquinone compounds such as t-butyldiphenoquinone;
In particular, as the electron-accepting compound, a compound having an anthraquinone structure is preferred. As the compound having an anthraquinone structure, for example, a hydroxyanthraquinone compound, an aminoanthraquinone compound, an aminohydroxyanthraquinone compound, etc. are preferable, and specifically, for example, anthraquinone, alizarin, quinizarin, anthralphine, purpurin, etc. are preferable.

The electron-accepting compound may be contained in the undercoat layer in a dispersed manner with the inorganic particles, or may be contained in a state attached to the surface of the inorganic particles.

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

In the dry method, for example, while stirring inorganic particles with a mixer with a large shearing force, an electron-accepting compound is dropped directly or dissolved in an organic solvent, and the electron-accepting compound is sprayed with dry air or nitrogen gas. This is a method of adhering to the surface of inorganic particles. When dropping or spraying the electron-accepting compound, it is preferable to do so at a temperature below the boiling point of the solvent. After dropping or spraying the electron-accepting compound, baking may be performed at a temperature of 100° C. or higher. There are no particular restrictions on the baking temperature and time as long as the electrophotographic properties can be obtained.

In the wet method, for example, an electron-accepting compound is added while dispersing inorganic particles in a solvent using stirring, ultrasonic waves, a sand mill, an attritor, a ball mill, etc., and after stirring or dispersion, the solvent is removed and the electron-accepting compound is added. This is a method in which a receptive compound is attached to the surface of an inorganic particle. The solvent is removed by, for example, filtration or distillation. After removing the solvent, baking may be further performed at 100° C. or higher. There are no particular limitations on the baking temperature and time as long as the electrophotographic properties can be obtained. In the wet method, the water contained in the inorganic particles may be removed before adding the electron-accepting compound, examples of which include removing the water while stirring and heating it in a solvent, and removing it by azeotroping with the solvent. Can be mentioned.

Note that the electron-accepting compound may be attached before or after the inorganic particles are subjected to surface treatment with a surface treatment agent, or may be carried out simultaneously with the attachment of the electron-accepting compound and the surface treatment with the surface treatment agent.

The content of the electron-accepting compound is, for example, preferably 0.01% by mass or more and 20% by mass or less, and preferably 0.01% by mass or more and 10% by mass or less based on the inorganic particles.

Examples of the binder resin used in the undercoat layer include acetal resin (for example, polyvinyl butyral), polyvinyl alcohol resin, polyvinyl acetal resin, casein resin, polyamide resin, cellulose resin, gelatin, polyurethane resin, polyester resin, and unsaturated polyester. Resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinyl acetate resin, vinyl chloride-vinyl acetate-maleic anhydride resin, silicone resin, silicone-alkyd resin, urea resin, phenol resin, phenol-formaldehyde resin, melamine resin, Known materials include known polymer compounds such as urethane resins, alkyd resins, and epoxy resins; zirconium chelate compounds; titanium chelate compounds; aluminum chelate compounds; titanium alkoxide compounds; organic titanium compounds; and silane coupling agents.
Examples of the binder resin used in the undercoat layer include charge transporting resins having a charge transporting group, conductive resins (eg, polyaniline, etc.), and the like.

Among these, resins that are insoluble in the coating solvent of the upper layer are suitable as the binder resin for the undercoat layer, and in particular, urea resins, phenol resins, phenol-formaldehyde resins, melamine resins, urethane resins, and unsaturated polyesters are suitable. Thermosetting resins such as resins, alkyd resins, and epoxy resins; at least one resin selected from the group consisting of polyamide resins, polyester resins, polyether resins, methacrylic resins, acrylic resins, polyvinyl alcohol resins, and polyvinyl acetal resins; Resins obtained by reaction with curing agents are preferred.
When using a combination of two or more of these binder resins, the mixing ratio is determined as necessary.

The undercoat layer may contain various additives to improve electrical properties, environmental stability, and image quality.
Examples of additives include known materials such as polycyclic condensation type, azo type electron transport pigments, zirconium chelate compounds, titanium chelate compounds, aluminum chelate compounds, titanium alkoxide compounds, organic titanium compounds, and silane coupling agents. It will be done. The silane coupling agent is used for surface treatment of inorganic particles as described above, but it may also be added to the undercoat layer as an additive.

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

Examples of zirconium chelate compounds include zirconium butoxide, zirconium ethyl acetoacetate, zirconium triethanolamine, acetylacetonate zirconium butoxide, acetoacetate ethyl zirconium butoxide, zirconium acetate, zirconium oxalate, zirconium lactate, zirconium phosphonate, zirconium octoate, Zirconium naphthenate, zirconium laurate, zirconium stearate, zirconium isostearate, methacrylate zirconium butoxide, stearate zirconium butoxide, isostearate zirconium butoxide, and the like.

Examples of titanium chelate compounds include tetraisopropyl titanate, tetra-n-butyl titanate, butyl titanate dimer, tetra (2-ethylhexyl) titanate, titanium acetylacetonate, polytitanium acetylacetonate, titanium octylene glycolate, and titanium lactate ammonium salt. , titanium lactate, titanium lactate ethyl ester, titanium triethanolaminate, polyhydroxytitanium stearate, and the like.

Examples of the aluminum chelate compound include aluminum isopropylate, monobutoxyaluminum diisopropylate, aluminum butyrate, diethylacetoacetate aluminum diisopropylate, aluminum tris (ethylacetoacetate), and the like.

These additives may be used alone or as a mixture or polycondensate of multiple compounds.

The undercoat layer preferably has a Vickers hardness of 35 or more.
The surface roughness (ten-point average roughness) of the undercoat layer ranges from 1/(4n) (n is the refractive index of the upper layer) to 1/2 of the exposure laser wavelength λ used to suppress moiré images. It is good to have it adjusted to
Resin particles or the like may be added to the undercoat layer to adjust the surface roughness. Examples of the resin particles include silicone resin particles and crosslinked polymethyl methacrylate resin particles. Further, the surface of the undercoat layer may be polished to adjust the surface roughness. Examples of the polishing method include buffing, sandblasting, wet honing, and grinding.

There are no particular restrictions on the formation of the undercoat layer, and well-known formation methods may be used. and heat as necessary.

As the solvent for preparing the coating solution for forming the undercoat layer, known organic solvents such as alcohol solvents, aromatic hydrocarbon solvents, halogenated hydrocarbon solvents, ketone solvents, ketone alcohol solvents, and ether solvents can be used. Examples include solvents and ester solvents.
Specific examples of these solvents include methanol, ethanol, n-propanol, iso-propanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, ethyl acetate, Common organic solvents include n-butyl acetate, dioxane, tetrahydrofuran, methylene chloride, chloroform, chlorobenzene, and toluene.

Examples of methods for dispersing inorganic particles when preparing a coating solution for forming an undercoat layer include known methods such as a roll mill, a ball mill, a vibrating ball mill, an attriter, a sand mill, a colloid mill, and a paint shaker.

Examples of methods for applying the coating solution for forming an undercoat layer onto the conductive substrate include blade coating, wire bar coating, spray coating, dip coating, bead coating, air knife coating, and curtain coating. For example, conventional methods such as

The thickness of the undercoat layer is, for example, preferably 15 μm or more, more preferably 20 μm or more and 50 μm or less.

(middle class)
Although not shown, an intermediate layer may be further provided between the undercoat layer and the photosensitive layer.
The intermediate layer is, for example, a layer containing resin. Examples of the resin used for the intermediate layer include acetal resin (e.g., polyvinyl butyral), polyvinyl alcohol resin, polyvinyl acetal resin, casein resin, polyamide resin, cellulose resin, gelatin, polyurethane resin, polyester resin, methacrylic resin, acrylic resin, Examples include polymeric compounds such as polyvinyl chloride resin, polyvinyl acetate resin, vinyl chloride-vinyl acetate-maleic anhydride resin, silicone resin, silicone-alkyd resin, phenol-formaldehyde resin, and melamine resin.
The intermediate layer may be a layer containing an organometallic compound. Examples of the organometallic compound used in the intermediate layer include organometallic compounds containing metal atoms such as zirconium, titanium, aluminum, manganese, and silicon.
The compounds used in these intermediate layers may be used alone or as a mixture or polycondensate of a plurality of compounds.

Among these, the intermediate layer is preferably a layer containing an organometallic compound containing a zirconium atom or a silicon atom.

There are no particular restrictions on the formation of the intermediate layer, and well-known formation methods may be used. This is done by heating according to the conditions.
As a coating method for forming the intermediate layer, conventional methods such as dip coating, push-up coating, wire bar coating, spray coating, blade coating, knife coating, and curtain coating can be used.

The thickness of the intermediate layer is, for example, preferably set in a range of 0.1 μm or more and 3 μm or less. Note that the intermediate layer may be used as a subbing layer.

(charge generation layer)
The charge generation layer is, for example, a layer containing a charge generation material and a binder resin. Further, the charge generation layer may be a deposited layer of a charge generation material. The vapor-deposited layer of charge-generating material is suitable when using a non-coherent light source such as a light emitting diode (LED) or an electro-luminescence (EL) image array.

Examples of the charge generating material include azo pigments such as bisazo and trisazo; condensed aromatic pigments such as dibromoanthanthrone; perylene pigments; pyrrolopyrrole pigments; phthalocyanine pigments; zinc oxide; and trigonal selenium.

Among these, it is preferable to use a metal phthalocyanine pigment or a metal-free phthalocyanine pigment as the charge-generating material in order to make it compatible with laser exposure in the near-infrared region. Specifically, for example, hydroxygallium phthalocyanine disclosed in JP-A-5-263007, JP-A-5-279591, etc.; chlorogallium phthalocyanine disclosed in JP-A-5-98181, etc.; Dichlorotin phthalocyanine disclosed in JP-A-140472, JP-A-5-140473 and the like; titanyl phthalocyanine disclosed in JP-A-4-189873 and the like are more preferred.

On the other hand, in order to be compatible with laser exposure in the near-ultraviolet region, charge-generating materials include condensed aromatic pigments such as dibromoanthanthrone; thioindigo pigments; porphyrazine compounds; zinc oxide; trigonal selenium; Bisazo pigments disclosed in JP-A No. 2004-78147 and JP-A No. 2005-181992 are preferred.

The charge-generating material described above may also be used when using an incoherent light source such as an LED or an organic EL image array that has an emission center wavelength of 450 nm or more and 780 nm or less, but from the viewpoint of resolution, the photosensitive layer should be 20 μm or less in thickness. When used in a thin film, the electric field strength in the photosensitive layer becomes high, and a decrease in charging due to charge injection from the substrate tends to cause image defects called so-called black spots. This becomes noticeable when charge generating materials such as trigonal selenium and phthalocyanine pigments, which are p-type semiconductors and tend to generate dark current, are used.

On the other hand, when n-type semiconductors such as condensed aromatic pigments, perylene pigments, and azo pigments are used as charge-generating materials, dark current is less likely to occur, and image defects called sunspots can be suppressed even in thin films. . Examples of n-type charge generating materials include compounds (CG-1) to (CG-27) described in paragraphs [0288] to [0291] of JP-A No. 2012-155282. It is not limited.
Note that the n-type is determined by the polarity of the flowing photocurrent using the commonly used time-of-flight method, and the n-type is determined if it is easier to flow electrons as carriers than holes.

The binder resin used in the charge generation layer is selected from a wide range of insulating resins, and the binder resin is selected from organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene, polyvinylpyrene, and polysilane. You may choose.
Examples of the binder resin include polyvinyl butyral resin, polyarylate resin (polycondensate of bisphenols and aromatic divalent carboxylic acid, etc.), polycarbonate resin, polyester resin, phenoxy resin, vinyl chloride-vinyl acetate copolymer, Examples include polyamide resin, acrylic resin, polyacrylamide resin, polyvinylpyridine resin, cellulose resin, urethane resin, epoxy resin, casein, polyvinyl alcohol resin, polyvinylpyrrolidone resin, and the like. Here, "insulating" means that the volume resistivity is 10 ¹³ Ωcm or more.
These binder resins may be used alone or in combination of two or more.

Note that the blending ratio of the charge generating material and the binder resin is preferably within the range of 10:1 to 1:10 in terms of mass ratio.

The charge generation layer may also contain other well-known additives.

There are no particular restrictions on the formation of the charge generation layer, and well-known formation methods may be used. and heat as necessary. Note that the charge generation layer may be formed by vapor deposition of a charge generation material. Formation of the charge generation layer by vapor deposition is particularly suitable when a condensed aromatic pigment or perylene pigment is used as the charge generation material.

Examples of the solvent for preparing the coating solution for forming the charge generation layer include methanol, ethanol, n-propanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, and n-acetic acid. -butyl, dioxane, tetrahydrofuran, methylene chloride, chloroform, chlorobenzene, toluene and the like. These solvents may be used alone or in combination of two or more.

Examples of methods for dispersing particles (for example, charge generating material) in the coating liquid for forming a charge generating layer include media dispersing machines such as ball mills, vibrating ball mills, attritors, sand mills, and horizontal sand mills, stirring machines, and ultrasonic dispersing machines. Medialess dispersion machines such as , roll mills, and high-pressure homogenizers are used. Examples of the high-pressure homogenizer include a collision method in which the dispersion liquid is dispersed by liquid-liquid collision or liquid-wall collision under high pressure, and a penetration method in which the dispersion is dispersed by penetrating fine channels under high pressure.
In addition, during this dispersion, it is effective to keep the average particle size of the charge generating material in the coating liquid for forming a charge generating layer to 0.5 μm or less, preferably 0.3 μm or less, and more preferably 0.15 μm or less. .

Examples of methods for applying the charge generation layer forming coating liquid onto the subbing layer (or onto the intermediate layer) include blade coating, wire bar coating, spray coating, dip coating, bead coating, and air knife coating. For example, conventional methods such as a coating method and a curtain coating method may be used.

The thickness of the charge generation layer is, for example, preferably set within a range of 0.1 μm or more and 5.0 μm or less, more preferably 0.2 μm or more and 2.0 μm or less.

(charge transport layer)
The charge transport layer is, for example, a layer containing a charge transport material and a binder resin. The charge transport layer may be a layer containing a polymeric charge transport material.

As charge transport materials, quinone compounds such as p-benzoquinone, chloranil, bromanil, and anthraquinone; tetracyanoquinodimethane compounds; fluorenone compounds such as 2,4,7-trinitrofluorenone; xanthone compounds; benzophenone compounds Examples include electron transporting compounds such as cyanovinyl compounds; ethylene compounds. Examples of the charge transporting material include hole transporting compounds such as triarylamine compounds, benzidine compounds, arylalkane compounds, aryl-substituted ethylene compounds, stilbene compounds, anthracene compounds, and hydrazone compounds. These charge transport materials may be used alone or in combination of two or more, but are not limited thereto.

As the charge transport material, from the viewpoint of charge mobility, a triarylamine derivative represented by the following structural formula (a-1) and a benzidine derivative represented by the following structural formula (a-2) are preferable.

In structural formula (a-1), Ar ^T1 , Ar ^T2 , and Ar ^T3 each independently represent a substituted or unsubstituted aryl group, -C ₆ H ₄ -C(R ^T4 )=C(R ^T5 )(R ^T6 ), or -C ₆ H ₄ -CH=CH-CH=C(R ^T7 )(R ^T8 ). R ^T4 , R ^T5 , R ^T6 , R ^T7 , and R ^T8 each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group.
Examples of substituents for each of the above groups include a halogen atom, an alkyl group having 1 to 5 carbon atoms, and an alkoxy group having 1 to 5 carbon atoms. Furthermore, examples of the substituents for each of the above groups include a substituted amino group substituted with an alkyl group having 1 or more and 3 or less carbon atoms.

In structural formula (a-2), R ^T91 and R ^T92 each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms. ^RT101 , ^RT102 , ^RT111 and ^RT112 are each independently substituted with a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or an alkyl group having 1 to 2 carbon atoms represents an amino group, a substituted or unsubstituted aryl group, -C(R ^T12 )=C(R ^T13 )(R ^T14 ), or -CH=CH-CH=C(R ^T15 )(R ^T16 ), R ^T12 , R ^T13 , R ^T14 , R ^T15 and R ^T16 each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group. Tm1, Tm2, Tn1 and Tn2 each independently represent an integer of 0 or more and 2 or less.
Examples of substituents for each of the above groups include a halogen atom, an alkyl group having 1 to 5 carbon atoms, and an alkoxy group having 1 to 5 carbon atoms. Furthermore, examples of the substituents for each of the above groups include a substituted amino group substituted with an alkyl group having 1 or more and 3 or less carbon atoms.

Here, among the triarylamine derivative represented by the structural formula (a-1) and the benzidine derivative represented by the structural formula (a-2), in particular, "-C ₆ H ₄ -CH=CH-CH= Triarylamine derivatives having "C(R ^T7 )(R ^T8 )" and benzidine derivatives having "-CH=CH-CH=C(R ^T15 )(R ^T16 )" are preferred from the viewpoint of charge mobility.

As the polymeric charge transporting material, known materials having charge transporting properties such as poly-N-vinylcarbazole and polysilane are used. In particular, polyester-based polymer charge transport materials disclosed in JP-A-8-176293 and JP-A-8-208820 are particularly preferred. Note that the polymer charge transport material may be used alone, or may be used in combination with a binder resin.

The binder resin used for the charge transport layer includes polycarbonate resin, polyester resin, polyarylate resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinylidene chloride resin, polystyrene resin, polyvinyl acetate resin, styrene-butadiene copolymer, Vinylidene chloride-acrylonitrile copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, silicone resin, silicone alkyd resin, phenol-formaldehyde resin, styrene-alkyd resin, poly-N -Vinyl carbazole, polysilane, etc. Among these, polycarbonate resin or polyarylate resin is suitable as the binder resin. These binder resins may be used alone or in combination of two or more.
Note that the blending ratio of the charge transport material and the binder resin is preferably from 10:1 to 1:5 in terms of mass ratio.

The charge transport layer may also contain other well-known additives.

There are no particular restrictions on the formation of the charge transport layer, and well-known formation methods may be used. , by heating if necessary.

Examples of solvents for preparing the coating solution for forming the charge transport layer include aromatic hydrocarbons such as benzene, toluene, xylene, and chlorobenzene; ketones such as acetone and 2-butanone; and methylene chloride, chloroform, and ethylene chloride. Halogenated aliphatic hydrocarbons; common organic solvents such as cyclic or linear ethers such as tetrahydrofuran and ethyl ether; These solvents may be used alone or in combination of two or more.

Application methods for applying the charge transport layer forming coating liquid onto the charge generation layer include blade coating, wire bar coating, spray coating, dip coating, bead coating, air knife coating, and curtain coating. Usual methods such as coating methods can be used.

The thickness of the charge transport layer is, for example, preferably set within a range of 5 μm or more and 50 μm or less, more preferably 10 μm or more and 30 μm or less.

(protective layer)
A protective layer is provided on the photosensitive layer as necessary. The protective layer is provided, for example, for the purpose of preventing chemical changes in the photosensitive layer during charging or further improving the mechanical strength of the photosensitive layer.
Therefore, it is preferable to apply a layer made of a cured film (crosslinked film) (that is, a protective layer having a crosslinked structure) as the protective layer. Examples of these layers include the layers shown in 1) or 2) below.

1) A layer composed of a cured film of a composition containing a reactive group-containing charge transporting material having a reactive group and a charge transporting skeleton in the same molecule (i.e., a polymer or crosslinked layer of the reactive group-containing charge transporting material) layer including the body)
2) A layer composed of a cured film of a composition containing a non-reactive charge transporting material and a reactive group-containing non-charge transporting material that does not have a charge transporting skeleton and has a reactive group (that is, A layer containing a non-reactive charge transport material and a polymer or crosslinked product of the non-reactive charge transport material)

The reactive groups of the reactive group-containing charge transport material include chain polymerizable groups, epoxy groups, -OH, -OR [wherein R represents an alkyl group], -NH ₂ , -SH, -COOH, -SiR ^Q1 _3-Qn (OR ^Q2 ) _Qn [However, R ^Q1 represents a hydrogen atom, an alkyl group, or a substituted or unsubstituted aryl group, and R ^Q2 represents a hydrogen atom, an alkyl group, or a trialkylsilyl group. Qn represents an integer of 1 to 3] and other well-known reactive groups.

The chain polymerizable group is not particularly limited as long as it is a functional group that can undergo radical polymerization, and is, for example, a functional group having at least a carbon double bond. Specifically, examples thereof include groups containing at least one selected from a vinyl group, a vinyl ether group, a vinyl thioether group, a styryl group (vinylphenyl group), an acryloyl group, a methacryloyl group, and derivatives thereof. Among these, groups containing at least one selected from vinyl groups, styryl groups (vinylphenyl groups), acryloyl groups, methacryloyl groups, and derivatives thereof are preferred as chain polymerizable groups due to their excellent reactivity. It is preferable that

The charge-transporting skeleton of the charge-transporting material containing a reactive group is not particularly limited as long as it has a known structure for electrophotographic photoreceptors, and examples thereof include triarylamine-based compounds, benzidine-based compounds, hydrazone-based compounds, etc. Examples include a structure derived from a nitrogen-containing hole-transporting compound and conjugated with a nitrogen atom. Among these, a triarylamine skeleton is preferred.

These reactive group-containing charge transport materials having a reactive group and a charge transport skeleton, non-reactive charge transport materials, and reactive group-containing non-charge transport materials may be selected from known materials.

The protective layer may also contain other well-known additives.

There are no particular restrictions on the formation of the protective layer, and well-known formation methods may be used; for example, a coating film of a coating solution for forming a protective layer in which the above components are added to a solvent is formed, the coating film is dried, This is done by performing a hardening process such as heating, if necessary.

Solvents for preparing the coating solution for forming the protective layer include aromatic solvents such as toluene and xylene; ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; ester solvents such as ethyl acetate and butyl acetate; tetrahydrofuran. , ether solvents such as dioxane; cellosolve solvents such as ethylene glycol monomethyl ether; alcohol solvents such as isopropyl alcohol and butanol. These solvents may be used alone or in combination of two or more.
In addition, the coating liquid for forming a protective layer may be a solvent-free coating liquid.

Methods for applying the protective layer forming coating solution onto the photosensitive layer (for example, charge transport layer) include dip coating, push-up coating, wire bar coating, spray coating, blade coating, knife coating, and curtain coating. Ordinary methods such as the method can be mentioned.

The thickness of the protective layer is, for example, preferably set within a range of 1 μm or more and 20 μm or less, more preferably 2 μm or more and 10 μm or less.

(Single layer type photosensitive layer)
The single-layer type photosensitive layer (charge generation/charge transport layer) is a layer containing, for example, a charge generation material, a charge transport material, and, if necessary, a binder resin and other well-known additives. Note that these materials are the same as those described for the charge generation layer and the charge transport layer.
The content of the charge generating material in the single-layer photosensitive layer is preferably 0.1% by mass or more and 10% by mass or less, preferably 0.8% by mass or more and 5% by mass or less based on the total solid content. . Further, the content of the charge transporting material in the single-layer type photosensitive layer is preferably 5% by mass or more and 50% by mass or less based on the total solid content.
The method for forming the single-layer type photosensitive layer is the same as the method for forming the charge generation layer and the charge transport layer.
The thickness of the single-layer type photosensitive layer is, for example, preferably 5 μm or more and 50 μm or less, preferably 10 μm or more and 40 μm or less.

[Image forming device (and process cartridge)]
The image forming apparatus according to the present embodiment includes an electrophotographic photoreceptor, a charging unit that charges the surface of the electrophotographic photoreceptor, and an electrostatic latent image forming device that forms an electrostatic latent image on the surface of the charged electrophotographic photoreceptor. a developing means for forming a toner image by developing an electrostatic latent image formed on the surface of the electrophotographic photoreceptor with a developer containing toner; and a transfer means for transferring the toner image onto the surface of the recording medium; Equipped with The electrophotographic photoreceptor according to the present embodiment is applied as the electrophotographic photoreceptor.

The image forming apparatus according to the present embodiment includes a fixing means for fixing a toner image transferred to the surface of a recording medium; direct transfer for directly transferring a toner image formed on the surface of an electrophotographic photoreceptor to a recording medium; An intermediate transfer system that primarily transfers the toner image formed on the surface of an electrophotographic photoreceptor onto the surface of an intermediate transfer member, and secondarily transfers the toner image transferred to the surface of the intermediate transfer member onto the surface of a recording medium. An apparatus equipped with a cleaning means that cleans the surface of the electrophotographic photoreceptor after the toner image is transferred and before charging; an apparatus that irradiates the surface of the electrophotographic photoreceptor with neutralizing light after the toner image is transferred and before charging. Well-known image forming apparatuses such as an apparatus equipped with a static eliminator for eliminating static electricity by using a static eliminator and an apparatus equipped with an electrophotographic photoreceptor heating member for increasing the temperature of the electrophotographic photoreceptor and reducing its relative temperature are applied.

In the case of an intermediate transfer type device, the transfer means includes, for example, an intermediate transfer body on which a toner image is transferred, and a primary transfer body that primarily transfers a toner image formed on the surface of an electrophotographic photoreceptor onto the surface of the intermediate transfer body. A configuration including a transfer means and a secondary transfer means that secondarily transfers the toner image transferred to the surface of the intermediate transfer member to the surface of the recording medium is applied.

The image forming apparatus according to this embodiment may be either a dry developing type image forming apparatus or a wet developing type image forming apparatus (a developing type using a liquid developer).

In the image forming apparatus according to the present embodiment, for example, the portion including the electrophotographic photoreceptor may have a cartridge structure (process cartridge) that is detachable from the image forming apparatus. As the process cartridge, for example, a process cartridge including the electrophotographic photoreceptor according to this embodiment is suitably used. In addition to the electrophotographic photoreceptor, the process cartridge may also include, for example, at least one selected from the group consisting of charging means, electrostatic latent image forming means, developing means, and transfer means.

An example of an image forming apparatus according to this embodiment will be shown below, but the present invention is not limited thereto. Note that the main parts shown in the figure will be explained, and the explanation of the others will be omitted.

FIG. 2 is a schematic configuration diagram showing an example of an image forming apparatus according to this embodiment.
As shown in FIG. 2, the image forming apparatus 100 according to the present embodiment includes a process cartridge 300 including an electrophotographic photoreceptor 7, an exposure device 9 (an example of electrostatic latent image forming means), and a transfer device 40 (primary (transfer device) and an intermediate transfer body 50. In the image forming apparatus 100, the exposure device 9 is arranged at a position where it can expose the electrophotographic photoreceptor 7 from the opening of the process cartridge 300, and the transfer device 40 exposes the electrophotographic photoreceptor 7 via the intermediate transfer member 50. The intermediate transfer body 50 is disposed at a position opposite to the electrophotographic photoreceptor 7 , and a portion of the intermediate transfer body 50 is disposed in contact with the electrophotographic photoreceptor 7 . Although not shown, it also includes a secondary transfer device that transfers the toner image transferred to the intermediate transfer member 50 onto a recording medium (for example, paper). Note that the intermediate transfer body 50, the transfer device 40 (primary transfer device), and the secondary transfer device (not shown) correspond to an example of the transfer means.

The process cartridge 300 in FIG. 2 integrates an electrophotographic photoreceptor 7, a charging device 8 (an example of a charging device), a developing device 11 (an example of a developing device), and a cleaning device 13 (an example of a cleaning device) in a housing. I support it. The cleaning device 13 includes a cleaning blade (an example of a cleaning member) 131, and the cleaning blade 131 is arranged so as to be in contact with the surface of the electrophotographic photoreceptor 7. Note that the cleaning member may be a conductive or insulating fibrous member instead of the cleaning blade 131, and may be used alone or in combination with the cleaning blade 131.

FIG. 2 shows, as an image forming apparatus, a fibrous member 132 (roll-shaped) that supplies the lubricant 14 to the surface of the electrophotographic photoreceptor 7, and a fibrous member 133 (flat brush-shaped) that assists in cleaning. Although an example is shown in which these are provided, these may be placed as necessary.

Each configuration of the image forming apparatus according to this embodiment will be described below.

-Charging device-
As the charging device 8, for example, a contact type charger using a conductive or semiconductive charging roller, a charging brush, a charging film, a charging rubber blade, a charging tube, etc. is used. In addition, chargers that are known per se, such as a non-contact type roller charger, a scorotron charger or a corotron charger that utilizes corona discharge, are also used.

-Exposure equipment-
Examples of the exposure device 9 include optical equipment that exposes the surface of the electrophotographic photoreceptor 7 with light such as semiconductor laser light, LED light, liquid crystal shutter light, etc. in a predetermined image manner. The wavelength of the light source is within the spectral sensitivity range of the electrophotographic photoreceptor. The mainstream wavelength of semiconductor lasers is near-infrared, which has an oscillation wavelength around 780 nm. However, the wavelength is not limited to this, and a laser having an oscillation wavelength of 600 nm or more or a blue laser having an oscillation wavelength of 400 nm or more and 450 nm or less may also be used. Furthermore, for color image formation, a surface-emitting laser light source capable of outputting multiple beams is also effective.

-Developing device-
As the developing device 11, for example, a general developing device that performs development by contacting or non-contacting the developer can be mentioned. The developing device 11 is not particularly limited as long as it has the above-mentioned functions, and is selected depending on the purpose. For example, a known developing device having a function of attaching a one-component developer or a two-component developer to the electrophotographic photoreceptor 7 using a brush, a roller, or the like can be used. Among these, those using a developing roller holding developer on its surface are preferred.

The developer used in the developing device 11 may be a one-component developer containing only toner, or a two-component developer containing toner and a carrier. Further, the developer may be magnetic or non-magnetic. As these developers, well-known ones can be used.

-Cleaning device-
As the cleaning device 13, a cleaning blade type device including a cleaning blade 131 is used.
In addition to the cleaning blade method, a fur brush cleaning method and a simultaneous development cleaning method may be employed.

-Transfer device-
As the transfer device 40, for example, a contact type transfer charger using a belt, a roller, a film, a rubber blade, etc., a scorotron transfer charger or a corotron transfer charger using corona discharge, and other known transfer chargers are used. Can be mentioned.

-Intermediate transfer body-
As the intermediate transfer member 50, a belt-shaped member (intermediate transfer belt) containing semiconductive polyimide, polyamideimide, polycarbonate, polyarylate, polyester, rubber, or the like is used. Moreover, as for the form of the intermediate transfer member, a drum-like member may be used instead of a belt-like member.

FIG. 3 is a schematic configuration diagram showing another example of the image forming apparatus according to the present embodiment.
The image forming apparatus 120 shown in FIG. 3 is a tandem multicolor image forming apparatus equipped with four process cartridges 300. In the image forming apparatus 120, four process cartridges 300 are arranged in parallel on the intermediate transfer member 50, and one electrophotographic photoreceptor is used for each color. Note that the image forming apparatus 120 has the same configuration as the image forming apparatus 100 except that it is of a tandem type.

(Other uses of dispersant-attached PTFE particles)
The dispersant-adhered PTEF particles according to the present embodiment are suitably used as an external additive for toners and as an external additive for powder coatings.
For example, when applying dispersant-attached PTEF particles as an external additive for a toner, an example of the toner is a toner for electrostatic image development that has toner particles and dispersant-attached PTEF particles as an external additive. The toner particles contain resin (binder resin). Note that the toner particles may contain other additives such as a colorant and a release agent, if necessary.
When applying dispersant-attached PTEF particles as an external additive for a powder coating, an example of the powder coating is a powder coating having powder particles and dispersant-attached PTEF particles as an external additive. The powder particles contain a thermosetting resin and a thermosetting agent. The powder particles may contain other additives such as a coloring agent, if necessary.

Examples of the present invention will be described below, but the present invention is not limited to the following examples. Note that "part" or "%" is based on mass unless otherwise specified.

<Example 1>
-Preparation of PTFE particles A-
Commercially available PTFE particles having an average particle size of 3.5 μm (primary particle size of 0.2 μm) were washed and then treated with a fluorine-containing dispersant as PTFE particles A.
400 parts by mass of tetrahydrofuran and 15 parts by mass of PTFE particles were collected, the pressure of a high-pressure homogenizer (LA-33S, manufactured by Nanomizer Co., Ltd., trade name) was set at 500 kg/ ^cm2 , and the above mixture was passed through this high-pressure homogenizer 4 times. Washing treatment was carried out by circulation. After the dispersion was further processed in a centrifuge, the upper transparent liquid was removed. Next, tetrahydrofuran was added so that the liquid amount was 415 parts by mass, and after dispersion treatment was performed again using a high-pressure homogenizer, the dispersion liquid was processed using a centrifuge, and the upper transparent liquid was discarded. After repeating this operation three more times, 1.5 parts of GF400 (manufactured by Toagosei Co., Ltd.: a surfactant containing at least a methacrylate having a fluorinated alkyl group as a polymerization component) was added as a fluorine-containing dispersant, and then Tetrohydrofuran was added to the solution so that the liquid amount was 415 parts by mass, and after dispersion treatment was performed again using a high-pressure homogenizer, the solvent was distilled off under reduced pressure. The dried particles were then ground in a mortar. These particles were designated as PTFE particles A.

-Measurement of PFOA content of PTFE particles A-
The "PFOA content" of PTFE particles A was measured according to the method described above, and was found to be 5 ppb.

-Preparation of PTFE composition LA-
45 parts of a benzidine compound represented by the following formula (CT-1) and 55 parts of a polymer compound (viscosity average molecular weight: 40,000) having a repeating unit represented by the following formula (B-1) were mixed with 350 parts of toluene. was dissolved in 150 parts of tetrahydrofuran, 10 parts of PTFE particles A were added thereto, and the mixture was treated with a high-pressure homogenizer 5 times to prepare a PTFE composition LA.

-Evaluation of PTFE composition LA-
The dispersion state of PTFE in the obtained PTFE composition LA was evaluated using a laser diffraction particle size distribution analyzer (Mastersizer 3000: Malvern), and the average particle size was 0.22 μm.

-Preparation and evaluation of PTFE layered material FA-
The PTFE composition LA was applied onto a glass substrate using a gap coater and heated at 130° C. for 45 minutes to produce a 5 μm thick PTFE layered material FA. The average particle size of the PTFE particles in the obtained layered material was 0.23 μm.

-Production of electrophotographic photoreceptor A-
Photoreceptor A was produced as follows.
・Formation of subbing layer Zinc oxide: 100 parts (average particle size 70 nm, manufactured by Teika Co., Ltd., specific surface area value 15 m2/g) was stirred and mixed with 500 parts of tetrahydrofuran, and a silane coupling agent (KBM503: manufactured by Shin-Etsu Chemical Co., Ltd.) was mixed. 1.3 parts were added and stirred for 2 hours. Thereafter, toluene was distilled off under reduced pressure, and baking was performed at 120° C. for 3 hours to obtain zinc oxide surface-treated with a silane coupling agent.
110 parts of the surface-treated zinc oxide was stirred and mixed with 500 parts of tetrahydrofuran, a solution of 0.6 parts of alizarin dissolved in 50 parts of tetrahydrofuran was added, and the mixture was stirred at 50° C. for 5 hours. Thereafter, the alizarin-added zinc oxide was filtered out by vacuum filtration, and further vacuum drying was performed at 60°C to obtain alizarin-added zinc oxide.
60 parts of this alizarin-imparted zinc oxide, 13.5 parts of a curing agent (blocked isocyanate Sumidur 3175, manufactured by Sumitomo Bayern Urethane), 15 parts of butyral resin (S-LEC BM-1, manufactured by Sekisui Chemical Co., Ltd.), and 85 parts of methyl ethyl ketone. were mixed to obtain a mixed solution. 38 parts of this mixed solution and 25 parts of methyl ethyl ketone were mixed and dispersed for 2 hours in a sand mill using glass beads of 1 mm diameter to obtain a dispersion.
To the obtained dispersion, 0.005 parts of dioctyltin dilaurate and 45 parts of silicone resin particles (Tospearl 145, Momentive Performance Materials Japan LLC) were added as a catalyst to obtain a coating liquid for an undercoat layer. Ta. This coating solution was applied by dip coating onto an aluminum base material with a diameter of 47 mm, a length of 357 mm, and a wall thickness of 1 mm, and dried and cured at 170° C. for 30 minutes to obtain a subbing layer with a thickness of 25 μm.

・Formation of charge generation layer Next, the Bragg angle (2θ±0.2°) in the X-ray diffraction spectrum is 7.5°, 9.9°, 12.5°, 16.3°, 18.6°, 1 part of hydroxygallium phthalocyanine having strong diffraction peaks at 25.1° and 28.3° was mixed with 1 part of polyvinyl butyral (S-LEC BM-S, manufactured by Sekisui Chemical Co., Ltd.) and 80 parts of n-butyl acetate. A coating solution for a charge generation layer was prepared by dispersing the mixture together with glass beads in a paint shaker for 1 hour. The resulting coating solution was dip coated onto the conductive support on which the undercoat layer had been formed, and was dried by heating at 100° C. for 10 minutes to form a charge generation layer with a thickness of 0.15 μm.

- Formation of charge transport layer PTFE composition A was coated on the above charge generation layer by dip coating, and heated at 130° C. for 45 minutes to form a charge transport layer with a thickness of 13 μm.

A photoreceptor was produced through the above steps.

-Evaluation of electrophotographic photoreceptor A-
The following evaluations were performed using the obtained photoreceptor.

-Visual evaluation The surface of the obtained photoreceptor (the surface of the charge transport layer) was visually observed.
A: No streaks are seen B: A faint streak-like defect is seen C: A streak-like defect is clearly seen

- Image quality evaluation The obtained photoreceptor was installed in an image forming apparatus "Apeos Port C4300 (manufactured by Fuji Xerox Co., Ltd.)". Using this device, 10,000 5% halftone images were output on A4 paper. The 1st, 100th, 5000th, and 10000th images were observed and evaluated for image defects. The evaluation criteria were as follows.
A: No image defects.
B: Slight image defects are seen when viewed with a magnifying glass. (at a level that does not pose a problem)
C: An image defect is visually observed.D: An obvious streaky image defect is observed.

<Example 2>
-Preparation of PTFE particles B-
Commercially available PTFE particles having an average particle size of 4.5 μm (primary particle size of 0.2 μm) were washed in the same manner as in Example 1, and then treated with a fluorine-containing dispersant to obtain PTFE particles B.

-Measurement of PFOA content of PTFE particles B-
Similarly to PTFE particles A, the "PFOA content" of PTFE particles B was measured according to the method described above, and was found to be 0 ppb.

-Preparation of PTFE composition LB-
A PTFE composition LB was prepared in the same manner as in Example 1, except that PTFE particles A were changed to PTFE particles B.

-Evaluation of PTFE composition LB-
The same evaluation as in Example 1 was performed except that PTFE composition LA was changed to PTFE composition LB. The results are shown in Table 1.

-Preparation and evaluation of PTFE layered material SB-
A PTFE layered material FB was produced and evaluated in the same manner as in Example 1, except that the PTFE composition LA was changed to the PTFE composition LB. The results are shown in Table 1.

-Production of electrophotographic photoreceptor B-
Electrophotographic photoreceptor B was prepared in the same manner as in Example 1 except that PTFE composition LA was changed to PTFE composition LB.

-Evaluation of electrophotographic photoreceptor B-
The obtained electrophotographic photoreceptor B was evaluated in the same manner as in Example 1. The results are shown in Table 1.

<Example 3>
In the production of PTEE particles A in Example 1, PTFE particles were used as PTFE particles C, which were washed and treated with a fluorine-containing dispersant so that the total amount of PFOA was 25 ppb.
After that, in the same manner as in Example 1 except that PTFE particles E were used instead of PTFE particles A, production and evaluation of PTFE composition LC, production and evaluation of PTFE composition LC, and PTFE layered material were performed. Fabrication and evaluation of FC and electrophotographic photoreceptor C were fabricated and evaluated. The results are shown in Table 1.

<Example 10>
In the production of PTEE particles A in Example 1, the PTFE particles were washed and treated with a fluorine-containing dispersant so that the total amount of PFOA was 0.01 ppb, and were used as PTFE particles D.
Thereafter, in the same manner as in Example 1 except that PTFE particles D were used in place of PTFE particles A, production and evaluation of PTFE composition LD, production and evaluation of PTFE layered material FD, and electrophotographic exposure were performed. Body D was prepared and evaluated. The results are shown in Table 1.

<Example 11>
In the production of PTEE particles A in Example 1, PTFE particles were used as PTFE particles F, which were washed and treated with a fluorine-containing dispersant so that the total amount of PFOA was 0.1 ppb.
Thereafter, in the same manner as in Example 1, except that PTFE particles F were used instead of PTFE particles A, production and evaluation of PTFE composition LF, production and evaluation of PTFE layered material FF, and electrophotographic exposure were performed. Body F was prepared and evaluated. The results are shown in Table 1.

<Example 12>
In the production of PTEE particles A in Example 1, PTFE particles were used as PTFE particles G, which were washed and treated with a fluorine-containing dispersant so that the total amount of PFOA was 15 ppb.
Thereafter, in the same manner as in Example 1, except that PTFE particles G were used instead of PTFE particles A, production and evaluation of PTFE composition LG, production and evaluation of PTFE layered material FG, and electrophotographic exposure were performed. Body G was prepared and evaluated. The results are shown in Table 1.

<Example 13>
In the production of PTEE particles A in Example 1, the PTFE particles were washed and treated with a fluorine-containing dispersant so that the total amount of PFOA was 20 ppb, and were used as PTFE particles H.
Thereafter, in the same manner as in Example 1, except that PTFE particles H were used instead of PTFE particles A, production and evaluation of PTFE composition LH, production and evaluation of PTFE layered material FH, and electrophotographic exposure were performed. Body H was prepared and evaluated. The results are shown in Table 1.

<Comparative example 1>
In the production of PTEE particles A in Example 1, the PTFE particles were washed and treated with a fluorine-containing dispersant so that the total amount of PFOA was 30 ppb, and were used as PTFE particles E.
Thereafter, in the same manner as in Example 1 except that PTFE particles E were used instead of PTFE particles A, PTFE composition LE was prepared and evaluated, PTFE composition LE was prepared and evaluated, and PTFE layered material F -E was fabricated and evaluated, and electrophotographic photoreceptor E was fabricated and evaluated. The results are shown in Table 1.

<Example 14>
-Preparation of PTFE composition L2-A-
Next, 9.5 parts by mass of a compound (IA) represented by the following structural formula, 0.5 parts by mass of Super Beckamine (R) L-148-55 (butylated benzoguanamine resin: manufactured by Dainippon Ink Co., Ltd.) , 0.1 part by mass of melamine resin (trade name: Nikalac Mw30, manufactured by Sanwa Chemical Co., Ltd.), 0.01 part by mass of polyether-modified silicone oil (trade name: KF355 (A), manufactured by Shin-Etsu Chemical Co., Ltd.), Blocked sulfonic acid (Commercial: Nacure 5225, manufactured by Kusumoto Kasei Co., Ltd.) 0.1 parts by mass, 20 parts by mass of cyclopentanol, and 5 parts by mass of 2-butanol were mixed. Further, 1 part by mass of PTFE particles A and 1 mm diameter glass beads were added, and after performing a dispersion treatment for 30 minutes in a paint shaker, the glass beads were removed. This liquid is referred to as PTFE composition L2-A.

-Production of electrophotographic photoreceptor-
A charge generation layer was prepared in the same manner as in Example 1.
Next, 2 parts by mass of a benzidine compound represented by the following formula (CT-1) and a polymer compound (viscosity average molecular weight of about 80,000) having a structural unit represented by the following formula (B-1). 5 parts by mass were dissolved in 35 parts by mass of chlorobenzene to obtain a coating liquid for forming a charge transport layer.
Next, the resulting coating solution was applied onto the charge generation layer by dip coating, and dried by heating at 120° C. for 40 minutes to form a charge transport layer with a thickness of 23 μm.

Next, PTFE composition L2-A was applied onto the charge transport layer by dip coating, air-dried at room temperature for 10 minutes, and then heat-treated at 150° C. for 1 hour to cure, forming a protective layer with a thickness of about 7 μm. was formed.
As a result, a desired electrophotographic photoreceptor (photoreceptor a) was obtained.
Then, in the same manner as in Example 1, various evaluations were performed.

<Example 15>
-Preparation of PTFE composition L2-B-
6 parts by mass of compound (III-2) represented by the following structural formula, 3 parts by mass of Me(MeO) ₂ -Si-(CH ₂ ) ₆ -Si-Me(OMe) ₂ , 20 parts by mass of cyclopentanol, Then, 5 parts by mass of isopropanol were mixed, and further 0.6 parts by mass of a cation exchange resin (trade name: Amberlyst 15E, manufactured by Rohm & Haas) and 0.5 parts by mass of distilled water were mixed for 30 minutes. Hydrolysis was performed. The ion exchange resin was filtered out from the hydrolyzed product, and 0.2 parts by mass of aluminum trisacetylacetonate and 0.2 parts by mass of acetylacetone were added to polyether-modified silicone oil (trade name: KF355(A), manufactured by Shin-Etsu Chemical Co., Ltd.) 0 .01 part by mass and 0.1 part by mass of blocked sulfonic acid (trade name: Nacure 5225, manufactured by Kusumoto Kasei Co., Ltd.) were added and mixed, and further 1 part by mass of PTFE particles B and 1 mmφ glass beads were added and mixed in a paint shaker. After 30 minutes of dispersion treatment, the glass beads were removed. This liquid is referred to as PTFE composition L2-B.

Here, in formula (III-2), each S represents -(CH ₂ ) ₂ -COO-(CH ₂ ) ₃ -Si(O-iPr) ₂ Me. Note that Me represents a methyl group and iPr represents an isopropyl group.

-Production of electrophotographic photoreceptor-
A charge transport layer was prepared in the same manner as in Example 11.
Next, PTFE composition L2-B was applied onto the charge transport layer by dip coating, air-dried at room temperature for 10 minutes, and then heat-treated at 150° C. for 1 hour to cure, forming a protective layer with a thickness of about 5 μm. was formed.
As a result, a desired electrophotographic photoreceptor (photoreceptor b) was obtained.
Then, in the same manner as in Example 1, various evaluations were performed.

<Example 16>
-Preparation of PTFE composition L2-C-
20 parts by mass of the compound represented by the following structural formula were dissolved in a mixture of 15 parts by mass of stabilizer-free tetrahydrofuran (THF) and 15 parts by mass of cyclopentyl methyl ether, and further 1 part by mass of PTFE particles C, and 1 mmφ glass beads. was added and subjected to dispersion treatment for 30 minutes using a paint shaker, and then the glass beads were removed. Further, 3.8 parts by mass of initiator V-601 (manufactured by Wako Pure Chemical Industries, Ltd.) was dissolved to obtain a coating solution for forming a protective layer. This liquid is referred to as PTFE composition L2-C.

-Production of electrophotographic photoreceptor-
A charge transport layer was prepared in the same manner as in Example 13.
PTFE composition L2-C was applied onto the charge transport layer and heated at 155° C. for 40 minutes in an atmosphere with an oxygen concentration of about 80 ppm to form a protective layer with a thickness of 7 μm.
As a result, the desired electrophotographic photoreceptor (photoreceptor c) was obtained. Then, in the same manner as in Example 1, various evaluations were performed.

<Example 4>
(Preparation and evaluation of powder coating)
A powder coating was prepared as follows using the PTFE particles A of Example 1 as an external additive.

-Preparation of polyester resin/curing agent composite dispersion (E1)-
A 3-liter jacketed reaction tank (manufactured by Tokyo Rika Kikai Co., Ltd.: BJ-30N) equipped with a condenser, thermometer, water dripping device, and anchor blade was maintained at 40°C in a water circulating thermostat. A mixed solvent of 180 parts of ethyl acetate and 80 parts of isopropyl alcohol was added to the solution, and the following composition was added thereto.
・Polyester resin (PES1) [polycondensate of terephthalic acid/ethylene glycol/neopentyl glycol/trimethylolpropane (molar ratio = 100/60/38/2 (mol%), glass transition temperature = 62°C, acid value ( Av) = 12 mgKOH/g, hydroxyl value (OHv) = 55 mgKOH/g, weight average molecular weight (Mw) = 12,000, number average molecular weight (Mn) = 4,000]: 240 parts Blocked isocyanate curing agent VESTAGON B1530 (EVONIK ): 60 parts ・Benzoin: 1.5 parts ・Acrylic oligomer (Acronal 4F, BASF): 3 parts

After charging, stirring was performed at 150 rpm using a three-one motor to dissolve and obtain an oil phase. A mixture of 1 part of a 10% by mass ammonia aqueous solution and 47 parts of a 5% by mass aqueous sodium hydroxide solution was added dropwise to this stirred oil phase over 5 minutes, and after mixing for 10 minutes, an additional 900% of ion-exchanged water was added to the stirred oil phase. 1 part was added dropwise at a rate of 5 parts per minute to invert the phase to obtain an emulsion.
Immediately, 800 parts of the obtained emulsion and 700 parts of ion-exchanged water were put into a 2-liter eggplant flask, and the flask was set in an evaporator (manufactured by Tokyo Rika Kikai Co., Ltd.) equipped with a vacuum control unit via a trap bulb. . While rotating the eggplant flask, it was heated in a hot water bath at 60° C., and the solvent was removed by reducing the pressure to 7 kPa while being careful not to bump. When the amount of solvent recovered reached 1100 parts, the pressure was returned to normal pressure (1 atm), and the eggplant flask was cooled with water to obtain a dispersion. The resulting dispersion had no solvent odor. The volume average particle diameter of the resin particles in this dispersion was 145 nm. Then, an anionic surfactant (manufactured by Dow Chemical, Dowfax 2A1, active ingredient amount 45% by mass) was added and mixed in an amount of 2% by mass as an active ingredient based on the resin content in the dispersion, and ion-exchanged water was added to reduce the solid content. The concentration was adjusted to 25% by mass. This was designated as a polyester resin/curing agent composite dispersion (E1).

-Preparation of white pigment dispersion (W1)-
・Titanium oxide (manufactured by Ishihara Sangyo A-220): 100 parts ・Anionic surfactant (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.: Neogen RK): 15 parts ・Ion exchange water: 400 parts ・0.3 mol/l nitric acid: 4 The above components were mixed, dissolved, and dispersed for 3 hours using a high-pressure impact dispersion machine Ultimizer (manufactured by Sugino Machine Co., Ltd., HJP30006) to prepare a white pigment dispersion in which titanium oxide was dispersed. When measured using a laser diffraction particle size analyzer, the volume average particle diameter of titanium oxide in the pigment dispersion was 0.28 μm, and the solid content ratio of the white pigment dispersion was 25%.

-Preparation of white powder particles (PC1)-
・Polyester resin/curing agent composite dispersion (E1): 180 parts (solid content 45 parts)
・White pigment dispersion (W1): 160 parts (solid content 40 parts)
- Ion exchange water: 200 parts or more were mixed and dispersed in a round stainless steel flask using a homogenizer (Ultra Turrax T50, manufactured by IKA). Next, the pH was adjusted to 3.5 using a 1.0% by mass nitric acid aqueous solution. 0.50 parts of a 10% by mass polyaluminum chloride aqueous solution was added to this, and the dispersion operation was continued using an Ultra Turrax.
Install a stirrer and a mantle heater, raise the temperature to 50℃ while adjusting the stirring rotation speed so that the slurry is sufficiently stirred, hold it at 50℃ for 15 minutes, and then heat the slurry using a Coulter counter [TA-II] type. (aperture diameter: 50 μm, manufactured by Beckman Coulter), and when the volume average particle size was 5.5 μm, polyester resin/curing agent composite dispersion (E1) 60 μm was used as a shell. (shell injection).

After being held for 30 minutes after the addition, the pH was adjusted to 7.0 using a 5% aqueous sodium hydroxide solution. Thereafter, the temperature was raised to 85°C and maintained for 2 hours.

After the reaction was completed, the solution in the flask was cooled and filtered to obtain solid content. Next, this solid content was washed with ion-exchanged water, and then subjected to solid-liquid separation by Nutsche suction filtration to obtain a solid content again.
Next, this solid content was redispersed in 3 liters of ion-exchanged water at 40°C, stirred and washed at 300 rpm for 15 minutes. This washing operation was repeated five times, and the solid content obtained by solid-liquid separation by Nutsche suction filtration was vacuum-dried for 12 hours to obtain core-shell type white powder particles (PC1).

When the particle size of this white powder particle (PC1) was measured, the volume average particle size D50v was 6.8 μm, the volume particle size distribution index GSDv was 1.24, and the average circularity was 0.97.

-Preparation of white powder paint-
White powder particles (PC1): 100 parts, 0.6 parts of silica particles "RX200 (Nippon Aerosil Co., Ltd.)" as an external additive, and 3 parts of the dispersant-attached PTFE particles of each example as an external additive. After mixing with a Henschel mixer at a circumferential speed of 32 m/s for 10 minutes, coarse particles were removed using a 45 μm mesh sieve to obtain a white powder coating.

-evaluation-
The following evaluations were performed using the obtained white powder coating.
The powder coating was loaded into Asahi Sunac Corona Gun XR4-110C.
Asahi Sunac Corona Gun The powder coating was discharged by sliding it left and right, and was electrostatically adhered to the panel to form an adhesion layer. The applied voltage of the corona gun was 80 kV, the input air pressure was 0.55 MPa, and the discharge rate was 200 g/min, and the amount of powder coating applied to the panel was 50 g/m ² , 90 g/m ² , 180 g/m ² , or Four coats were applied at 220 g/m ² .
Thereafter, each panel was placed in a high temperature chamber set at 180° C. and heated (baked) for 30 minutes.

The obtained coating film was evaluated by palpation and visual inspection. The evaluation criteria were as follows.
A: No problem with both palpation and visual inspection B: Slight unevenness can be seen visually (level that does not pose a problem)
C: A protrusion is confirmed by palpation (level that does not pose a problem)
D: Visual unevenness, protrusions seen by palpation.

<Example 5-6, Comparative Example 2>
(Preparation and evaluation of powder coating)
Powder coatings were produced and evaluated in the same manner as in Example 4, except that the PTFE particles B to E of Examples 2 to 3 and Comparative Example 1 were used as external additives.

A list of the above examples is shown in Tables 1 and 2.

From the above results, it can be seen that in this example, better results were obtained in both the photoreceptor evaluation and the powder coating evaluation than in the comparative example.
This shows that the PTFE particle dispersion (and the PEFT particles adhering to the dispersion) of this example has a high ability to maintain the dispersed state even if the state of the components to be mixed changes.

1 subbing layer, 2 charge generation layer, 3 charge transport layer, 4 conductive substrate, 7A, 7 electrophotographic photoreceptor, 8 charging device, 9 exposure device, 11 developing device, 13 cleaning device, 14 lubricant, 40 transfer device, 50 intermediate transfer body, 100 image forming device, 120 image forming device, 131 cleaning blade, 132 fibrous member (roll shape), 133 fibrous member (flat brush shape), 300 process cartridge

Claims (13)

A dispersant having a fluorine atom is attached to the surface, and the perfluorooctanoic acid content is 0 ppb or more and 25 ppb or less with respect to the polytetrafluoroethylene particles,
Dispersant-attached polytetrafluoroethylene particles, wherein the dispersant having a fluorine atom is a polymer obtained by homopolymerizing or copolymerizing a polymerizable compound having a fluorinated alkyl group. The dispersant-adhered polytetrafluoroethylene particles according to claim 1, having an average particle size of 0.2 μm or more and 4.5 μm or less. The polymer obtained by homopolymerizing or copolymerizing the above polymerizable compound having a fluorinated alkyl group is a fluorinated alkyl group-containing polymer having a structural unit represented by the following general formula (FA), or a fluorinated alkyl group-containing polymer having a structural unit represented by the following general formula (FA). The dispersant-adhered polytetrafluoroethylene particles according to claim 1 or 2 , which are a fluorinated alkyl group-containing polymer having the structural unit shown below and the structural unit shown by the following general formula (FB).


(In the general formulas (FA) and (FB), R ^F1 , R ^F2 , R ^F3 and R ^F4 each independently represent a hydrogen atom or an alkyl group. X ^F1 is an alkylene chain, a halogen-substituted alkylene chain, -S-, -O-, -NH-, or a single bond.Y ^F1 represents an alkylene chain, a halogen-substituted alkylene chain, -(C _fx H _2fx-1 (OH))-, or a single bond.Q ^F1 represents -O- or -NH-.fl, fm and fn each independently represent an integer of 1 or more.fp, fq, fr and fs each independently represent 0 or 1 or more Represents an integer. ft represents an integer between 1 and 7. fx represents an integer between 1 and more.) The dispersant-attached polytetrafluoroethylene particles according to claim 1, wherein the content of the dispersant having a fluorine atom is 0.5% by mass or more and 10% by mass or less based on the polytetrafluoroethylene particles. The dispersant-attached polytetrafluoroethylene particles according to claim 4 , wherein the content of the dispersant having a fluorine atom is 1% by mass or more and 7% by mass or less based on the polytetrafluoroethylene particles. Contains polytetrafluoroethylene particles and a dispersant having a fluorine atom,
The perfluorooctanoic acid content is 0 ppb or more and 25 ppb or less with respect to the polytetrafluoroethylene particles,
A composition in which the dispersant having a fluorine atom is a polymer obtained by homopolymerizing or copolymerizing a polymerizable compound having a fluorinated alkyl group. The composition according to claim 6 , wherein the polytetrafluoroethylene particles have an average particle size of 0.2 μm or more and 4.5 μm or less. The composition according to claim 6 or 7, which is in a liquid or solid state. comprising an electrically conductive substrate and a photosensitive layer provided on the electrically conductive substrate,
The outermost layer consists of a layered material containing polytetrafluoroethylene particles and a dispersant having a fluorine atom, and having a perfluorooctanoic acid content of 0 ppb or more and 25 ppb or less relative to the polytetrafluoroethylene particles. An electrophotographic photoreceptor that is a layer. The electrophotographic photoreceptor according to claim 9 , wherein the polytetrafluoroethylene particles have an average particle diameter of 0.2 μm or more and 4.5 μm or less. The electrophotographic photoreceptor according to claim 9 or 10 , wherein the outermost surface layer is a surface protective layer having a crosslinked structure. An electrophotographic photoreceptor according to any one of claims 9 to 11 ,
A process cartridge that can be attached to and removed from an image forming apparatus. The electrophotographic photoreceptor according to any one of claims 9 to 11 ,
Charging means for charging the surface of the electrophotographic photoreceptor;
an electrostatic latent image forming means for forming an electrostatic latent image on the charged surface of the electrophotographic photoreceptor;
a developing means for developing the electrostatic latent image formed on the surface of the electrophotographic photoreceptor to form a toner image with a developer containing toner;
a transfer means for transferring the toner image onto the surface of a recording medium;
An image forming apparatus comprising:

Images