JP2021060463A - Electrophotographic photoreceptor, process cartridge, and image forming apparatus - Google Patents

Abstract

To provide an electrophotographic photoreceptor that has high surface smoothness regardless of the type of fluorine-containing resin particles.SOLUTION: An electrophotographic photoreceptor has a conductive substrate and a photosensitive layer provided on the conductive substrate. An outermost surface layer includes fluorine-containing resin particles and a fluorine-based graft polymer having a fluorinated alkyl group. A molecular weight distribution curve of the fluorine-based graft polymer has two or more peaks. In the molecular weight distribution curve of the fluorine-based graft polymer, when the peak area of a peak P1 at which the molecular weight is minimum is S1 and the peak area of a peak P2 at which the molecular weight is maximum is S2, the relationship of S1≤S2 is satisfied.SELECTED DRAWING: None

Description

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

Conventionally, as an electrophotographic image forming apparatus, an electrophotographic photosensitive member (hereinafter, may be referred to as a “photoreceptor”) is used to sequentially perform steps such as charging, electrostatic latent image formation, development, transfer, and cleaning. The device to do is widely known.

The electrophotographic photosensitive member is a function-separated photoconductor in which a charge generating layer for generating electric charges and a charge transporting layer for transporting electric charges are laminated on a conductive substrate such as aluminum, or an electrophotographic photosensitive member that generates electric charges. A single-layer photoconductor in which the same layer performs a function and a function of transporting electric charge is known.

For example, Patent Document 1 states that "at least a photosensitive layer is provided on a conductive support, the surface layer contains a specific structural unit, the fluorine content is 10% by mass or more and 40% by mass or less, and the weight average. It has a molecular weight Mw of 50,000 or more and 200,000 or less, a weight average molecular weight Mw to a number average molecular weight Mn ratio [Mw / Mn] of 1 or more and 8 or less, and a perfluoroalkyl group having 1 or more and 6 or less carbon atoms. Electrons containing a fluorine-based graft polymer and fluorine-containing resin particles so that the content of the fluorine-based graft polymer is 0.5% by mass or more and 5.0% by mass or less with respect to the fluorine-containing resin particles. Photophotoreceptor. ”Is disclosed.

Japanese Patent No. 5544850

Conventionally, fluorine-containing resin particles have been blended in the outermost surface layer of an electrophotographic photosensitive member for the purpose of improving cleanability. Then, in order to enhance the dispersibility of the fluorine-containing resin particles, a dispersant such as a fluorine-based graft polymer is used.

However, when the outermost surface layer of the electrophotographic photosensitive member contains fluorine-containing resin particles and a fluorine-based graft polymer, the dispersed state is disrupted depending on the type of the fluorine-containing resin particles, and agglomerates are formed, resulting in surface smoothness. The sex may be reduced.

Therefore, the subject of the present invention is to have an outermost surface layer containing fluorine-containing resin particles and a fluorine-based graft polymer having an alkyl fluoride group, as compared with the case where the molecular weight distribution curve of the fluorine-based graft polymer has one peak. It is an object of the present invention to provide an electrophotographic photosensitive member having high surface smoothness regardless of the type of fluorine-containing resin particles.

The above problem is solved by the following means.

<1> A conductive substrate and a photosensitive layer provided on the conductive substrate are provided.
The outermost surface layer contains fluorine-containing resin particles and a fluorine-based graft polymer having an alkyl fluoride group.
The peak area of the peak P1 having two or more peaks in the molecular weight distribution curve of the fluorine-based graft polymer and the minimum molecular weight in the molecular weight distribution curve of the fluorine-based graft polymer is S1, and the molecular weight is An electrophotographic photosensitive member satisfying the relationship of S1 ≦ S2, where S2 is the peak area of the maximum peak P2.

<2> In the molecular weight distribution curve of the fluorine-based graft polymer, when the molecular weight of the maximum point of the peak P1 having the minimum molecular weight is M1 and the molecular weight of the maximum point of the peak P2 having the maximum molecular weight is M2, M1 < The electrophotographic photosensitive member according to <1>, which satisfies the relationship of M2 × 0.5.
<3> The electrophotographic photosensitive member according to <1> or <2>, wherein the molecular weight M2 is 50,000 or more and 200,000 or less.

<4> The outermost surface layer contains dispersant-adhered particles in which the fluorine-based graft polymer is adhered to the surface of the fluorine-containing resin particles, and the content of perfluorooctanoic acid in the dispersant-adhered particles is the fluorine-containing particles. The electrophotographic photosensitive member described in any one of <1> to <3>, which is 0 ppb or more and 25 ppb or less with respect to the total mass of the resin particles.
<5> The electrophotographic photosensitive member according to <4>, wherein the arithmetic average roughness Ra of the outermost surface layer is 0.13 μm or less.

<6> The electrophotographic photosensitive member according to any one of <1> to <5> is provided.
A process cartridge that can be attached to and detached from the image forming device.
<7> The electrophotographic photosensitive member according to any one of <1> to <5>,
A charging means for charging the surface of the electrophotographic photosensitive member and
An electrostatic latent image forming means for forming an electrostatic latent image on the surface of the charged electrophotographic photosensitive member,
A developing means for developing an electrostatic latent image formed on the surface of the electrophotographic photosensitive member with a developer containing toner to form a toner image, and a developing means.
A transfer means for transferring the toner image to the surface of a recording medium, and
An image forming apparatus comprising.

According to the invention according to <1>, when the outermost surface layer contains fluorine-containing resin particles and a fluorine-based graft polymer having a fluorine-based alkyl group, and the molecular weight distribution curve of the fluorine-based graft polymer has one peak. However, an electrophotographic photosensitive member having high surface smoothness is provided regardless of the type of fluorine-containing resin particles.

According to the invention according to <2> or <3>, an electrophotographic photosensitive member having higher surface smoothness is provided as compared with the case where the molecular weight M1 and the molecular weight M2 do not satisfy M1 <M2 × 0.5. ..

According to the invention according to <4>, the electrophotograph having higher surface smoothness than the case where the content of perfluorooctanoic acid in the dispersant-adhered particles exceeds 25 ppb with respect to the total mass of the fluorine-containing resin particles. Photoreceptors are provided.
According to the invention according to <5>, an electrophotographic photosensitive member having higher surface smoothness is provided as compared with the case where the surface roughness Ra of the outermost surface image exceeds 0.13 μm.

According to the invention according to <6> or <7>, the outermost surface layer contains fluorine-containing resin particles and a fluorine-based graft polymer having an alkyl fluoride group, and the molecular weight distribution curve of the fluorine-based graft polymer is 1. A process cartridge or an image forming apparatus provided with an electrophotographic photosensitive member having higher surface smoothness regardless of the type of fluorine-containing resin particles as compared with the case of having one peak is provided.

It is a schematic cross-sectional view which shows an example of the layer structure of the electrophotographic photosensitive member which concerns on this embodiment. It is a schematic block diagram which shows an example of the image forming apparatus which concerns on this embodiment. It is a schematic block diagram which shows another example of the image forming apparatus which concerns on this embodiment.

Hereinafter, embodiments that are an example of the present invention will be described in detail.

<Electrophotophotoreceptor>
The electrophotographic photosensitive member (hereinafter, also simply referred to as “photoreceptor”) according to the present embodiment has a conductive substrate and a photosensitive layer provided on the conductive substrate, and the outermost surface layer contains fluorine. Includes resin particles and a fluorine-based graft polymer having an alkyl fluoride group. Then, the peak area of the peak P1 having two or more peaks in the molecular weight distribution curve of the fluorine-based graft polymer contained in the outermost surface layer and having the smallest molecular weight in the molecular weight distribution curve of the fluorine-based graft polymer is S1. And when the peak area of the peak P2 having the maximum molecular weight is S2, the relationship of S1 ≦ S2 is satisfied.
The photoconductor according to the present embodiment has high surface smoothness regardless of the type of fluorine-containing resin particles. The reason is presumed as follows.

As described above, when the outermost surface layer of the electrophotographic photosensitive member contains fluorine-containing resin particles and a fluorine-based graft polymer, the dispersed state is disrupted depending on the type of fluorine-containing resin particles, and aggregates are generated. As a result, the surface smoothness may decrease.
Therefore, the present inventors have focused on a fluorine-based graft polymer used as a dispersant for fluorine-containing resin particles, and obtained the following findings.
First, in order to enhance the dispersibility of the fluorine-containing resin particles, it is preferable to (1) enhance the wettability of the fluorine-containing resin particles and (2) stabilize the dispersed state.
(1) To enhance the wettability of the fluorine-containing resin particles is specifically to reduce the surface tension of the surface of the fluorine-containing resin particles by using a fluorine-based graft polymer as a dispersant to make them compatible with the solvent. Further, (2) stabilizing the dispersed state specifically suppresses the fluorine-containing resin particles from approaching each other and aggregating due to the steric repulsion effect of the fluorine-based graft polymer as a dispersant. That is.
In order to achieve the above (2), it is preferable that the fluorine-containing resin particles do not come into contact with each other as much as possible and the dispersant adsorbed on the fluorine-containing resin particles does not desorb. Therefore, it is effective to increase the molecular weight of the fluorine-based graft polymer, which is a dispersant. However, since the high molecular weight dispersant is difficult to enter into the gaps between the fluorine-containing resin particles, it is not preferable from the viewpoint of (1) exhibiting the effect of enhancing the wettability of the fluorine-containing resin particles.
Therefore, by using a fluorine-based graft polymer having two or more peaks in the molecular weight distribution curve and satisfying the relationship of "S1 ≤ S2" as the dispersant, the above (1) and (2) can be used. It has been found that both are achieved, and that the fluorine-containing resin particles can be dispersed in a nearly uniform state and the dispersion stability can be improved.
As a result, the fluorine-containing resin particles are contained in the outermost surface layer in a state where the dispersibility is high and the agglomerates are small, regardless of the type (specifically, the types of particles having different production methods). , It is considered that it can be an electrophotographic photosensitive member having high surface smoothness.

Hereinafter, the photoconductor according to the present embodiment will be described in detail.

[Outermost layer]
In the photoconductor according to the present embodiment, the outermost surface layer contains fluorine-containing resin particles and a fluorine-based graft polymer having an alkyl fluoride group.
The outermost surface layer of the photoconductor corresponds to a charge transport layer, a protective layer, or a single-layer type photosensitive layer. The outermost surface layer contains components other than the fluorine-containing resin particles and the fluorine-based graft polymer, depending on the layer type. The other components will be described together with the configuration of each layer of the photoconductor.

[Fluorine-containing resin particles]
The fluorine-containing resin particles are homopolymer particles of fluoroolefin and a copolymer using two or more kinds of monomers, and one kind or two or more kinds of fluoroolefin and a non-fluorine-based monomer (that is, a fluorine atom) are used. Examples include particles of a copolymer with a non-existent monomer.

Examples of fluoroolefins include perhaloolefins such as tetrafluoroethylene (also referred to as TFE), perfluorovinyl ether, hexafluoropropylene (also referred to as HFP), and chlorotrifluoroethylene (also referred to as CTFE), and vinylidene fluoride (also referred to as VdF). ), Non-perfluoroolefins such as trifluoroethylene and vinyl fluoride can be mentioned. Among these, VdF, TFE, CTFE, HFP and the like are preferable.

On the other hand, examples of the non-fluorine-based monomer include hydrocarbon-based olefins such as ethylene, propylene and butene; alkyl vinyl ethers such as cyclohexyl vinyl ether (also referred to as CHVE), ethyl vinyl ether (also referred to as EVE), butyl vinyl ether and methyl vinyl ether; Alkenyl vinyl ethers such as polyoxyethylene allyl ether (also referred to as POEAE) and ethyl allyl ether; reactive α, β-unsaturated such as vinyl trimethoxysilane (also referred to as VSi), vinyl triethoxysilane and vinyl tris (methoxyethoxy) silane. Organic silicon compounds having a group; acrylic acid esters such as methyl acrylate and ethyl acrylate; methacrylic acid esters such as methyl methacrylate and ethyl methacrylate; vinyl acetate, vinyl benzoate, "Beova" (trade name, manufactured by Shell). Vinyl ester) and the like; Among these, alkyl vinyl ethers, vinyl esters, and organosilicon compounds having reactive α, β-unsaturated groups are preferable.

Among these, as the fluorine-containing resin particles, particles having a high fluorination rate are preferable, and polytetrafluoroethylene (also referred to as PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (also referred to as FEP), tetrafluoroethylene- Particles such as perfluoro (alkyl vinyl ether) copolymer (also referred to as PFA), ethylene-tetrafluoroethylene copolymer (also referred to as ETFE), and ethylene-chlorotrifluoroethylene copolymer (also referred to as ECTFE) are more preferable. PTFE, FEP, and PFA particles are particularly preferred.

The fluorine-containing resin particles include particles obtained by irradiation with radiation (hereinafter, also referred to as “irradiation-type fluorine-containing resin particles”) and particles obtained by a polymerization method (hereinafter, also referred to as “polymerized fluorine-containing resin particles”). ) Etc. can be mentioned.

The irradiation-type fluorine-containing resin particles refer to fluorine-containing resin particles granulated by radiation polymerization and fluorine-containing resin particles obtained by decomposing the fluorine-containing resin after polymerization by irradiation to reduce the amount and atomize. ..
Irradiation-type fluorine-containing resin particles are particles containing a large amount of carboxyl groups because a large amount of carboxylic acid is generated by irradiation with radiation in the air.

On the other hand, the polymerization type fluorine-containing resin particles indicate fluorine-containing resin particles that have been granulated together with polymerization by a suspension polymerization method, an emulsion polymerization method, or the like and have not been irradiated with radiation.
In the production of the fluorine-containing resin particles by the suspension polymerization method, for example, an additive such as a polymerization initiator and a catalyst is suspended together with a monomer for forming the fluorine-containing resin in a dispersion medium, and then the monomer is used. This is a method of atomizing a polymer while polymerizing it.
Further, in the production of fluorine-containing resin particles by the emulsion polymerization method, for example, in a dispersion medium, an additive such as a polymerization initiator and a catalyst is used as a surfactant (that is, an emulsifier) together with a monomer for forming a fluorine-containing resin. This is a method of granulating the polymer while polymerizing the monomer after emulsification.
Since the polymerization type fluorine-containing resin particles use the above-mentioned polymerization method, they are unlikely to be particles containing a large amount of carboxyl groups, unlike the irradiation-type fluorine-containing resin particles.

Whether the fluorine-containing resin particles are irradiation-type fluorine-containing resin particles or polymerized fluorine-containing resin particles, the dispersibility is improved by the fluorine-based graft polymer having a specific molecular weight distribution curve described later. , Can be a photoconductor with excellent surface smoothness.
In particular, when the fluorine-containing resin particles are polymerized fluorine-containing resin particles, the effect of improving dispersibility by the fluorine-based graft polymer having a specific molecular weight distribution curve described later is enhanced, so that the polymerized fluorine-containing resin A combination of the particles and a fluorinated graft polymer having a specific molecular weight distribution curve described later is preferable.

The number average particle size of the primary particles of the fluorine-containing resin particles is not particularly limited, but is preferably 0.1 μm or more and 1.0 μm or less, and more preferably 0.2 μm or more and 0.5 μm or less.

The number average particle diameter of the fluorine-containing resin particles is a value measured by the following method.
First, a sample piece is prepared from the outermost surface layer containing fluorine-containing resin particles. The obtained sample piece is observed with an SEM (scanning electron microscope) at a magnification of, for example, 5000 times or more, and the maximum diameter of the fluorine-containing resin particles in the primary particle state is measured, and this is performed for 50 particles. The average value of the maximum diameters of the 50 fluorine-containing resin particles in the primary particle state is calculated and used as the above-mentioned number average particle diameter.
Here, as the SEM, JSM-6700F manufactured by JEOL Ltd. is used, and a secondary electron image having an acceleration voltage of 5 kV is observed.

The fluorine-containing resin particles may be used alone or in combination of two or more.
The content of the fluorine-containing resin particles is preferably 1% by mass or more and 30% by mass or less, more preferably 3% by mass or more and 20% by mass or less, and 5% by mass or more and 15% by mass with respect to the total solid content of the outermost surface layer. The following is more preferable.

[Fluorine-based graft polymer]
Next, the fluorine-based graft polymer will be described.
The fluorine-based graft polymer is a fluorine-based graft polymer having an alkyl fluoride group, and contributes to the dispersibility of the fluorine-existing resin particles as a fluorine-containing dispersant.
In this embodiment, the fluorograft polymer has two or more peaks on its molecular weight distribution curve.

The molecular weight distribution curve of the fluorine-based graft polymer may have two or more peaks and may have three or more peaks, but the components constituting the peaks on the low molecular weight side and the high molecular weight side It is preferable to have two peaks from the viewpoint of clarifying the functional separation from the components constituting the peak.

In the molecular weight distribution curve of the fluorine-based graft polymer, from the viewpoint of enhancing the dispersibility of the fluorine-containing resin particles, the molecular weight of the maximum point of the peak P1 having the minimum molecular weight is set to M1, and the molecular weight of the maximum point of the peak P2 having the maximum molecular weight is set to M1. When M2, it is preferable to satisfy the relationship of M1 <M2 × 0.5, more preferably to satisfy the relationship of M1 <M2 × 0.4, and to satisfy the relationship of M1 <M2 × 0.3. More preferably, it is particularly preferable to satisfy the relationship of M1 <M2 × 0.2.

In the molecular weight distribution curve of the fluorine-based graft polymer, the molecular weight M2 at the maximum point of the peak P2 having the maximum molecular weight is preferably 50,000 or more and 200,000 or less from the viewpoint of enhancing the dispersibility of the fluorine-containing resin particles. It is more preferably 50,000 or more and 150,000 or less, and further preferably 100,000 or more and 150,000 or less.
In the molecular weight distribution curve of the fluorine-based graft polymer, the molecular weight M1 at the maximum point of the peak P1 having the minimum molecular weight is preferably 10,000 or more and 50,000 or less from the viewpoint of enhancing the dispersibility of the fluorine-containing resin particles. More preferably 10,000 or more and 40,000 or less.

In the molecular weight distribution curve of the fluorograft polymer, when the peak area of the peak P1 having the smallest molecular weight is S1 and the peak area of the peak P2 having the largest molecular weight is S2, the relationship of S1 ≦ S2 is satisfied. It is more preferable that the relationship of S1 <S2 is satisfied, and it is further preferable that the relationship of S1 × 1.5 ≦ S2 is satisfied.

The molecular weight of the fluorinated graft polymer is measured by gel permeation chromatography (GPC). The molecular weight measurement by GPC is performed, for example, by using Tosoh's GPC / HLC-8120 as a measuring device, using Tosoh's column / TSKgel GMHHR-M + TSKgel GMHHR-M (7.8 mm ID 30 cm), and using a tetrahydrofuran solvent. From this measurement result, a molecular weight calibration curve is created from the monodisperse polystyrene standard sample, and this is referred to as the "molecular weight distribution curve of the fluorograft polymer" in the present embodiment.
Then, from the obtained molecular weight distribution curve, the molecular weight M1 and the peak area S1 of the maximum point at the peak P1 having the minimum molecular weight, and the molecular weight M2 and the peak area S2 of the maximum point at the peak P2 having the maximum molecular weight can be obtained. ..

When obtaining the molecular weight distribution curve of the fluorine-based graft polymer contained in the outermost surface layer, the fluorine-based graft polymer as a measurement sample may be collected as follows.
The outermost surface layer is dissolved in a soluble solvent such as tetrahydrofuran, and the fluorine-containing fine particles adsorbed by the fluorine-based graft polymer are filtered through a 0.1 μm mesh filter. Next, the fluorocarbon-containing fine particles adsorbed by the fluorograft polymer obtained by filtration are subjected to aromatic hydrocarbons such as toluene and xylene, fluorocarbons, perfluorocarbons, hydrochlorofluorocarbons, methylene chlorides, and halogen solvents such as chloroform. Heat at 100 ° C. or lower in an ester solvent such as ethyl acetate or butyl acetate, a ketone solvent such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, or a mixed solvent in which two or more of these are mixed, and then filter. After drying, the fluorine-based graft polymer adsorbed on the surface of the fluorine-containing fine particles is eluted and collected.

The fluorine-based graft polymer having the above-mentioned molecular weight distribution curve can be obtained by mixing two or more kinds of fluorine-based graft polymers having different molecular weights at a desired quantity ratio. The fluorine-based graft polymer to be mixed may be a fluorine-based graft polymer having the same constitutional unit, or may be a fluorine-based graft polymer having different constitutional units.

The fluorograft polymer has an alkyl fluoride group. Specifically, for example, at least a copolymer of a monomer having an alkyl fluoride group and a monomer having no alkyl fluoride group and having an ester group are copolymerized. The polymer obtained is a preferable example.

Specifically, as a fluorine-based graft polymer, a random or block co-weight of a (meth) acrylate having an alkyl fluoride group and a monomer having no alkyl fluoride group and having an ester group (> C = 0). Coalescence and the like can be mentioned. The (meth) acrylate means both acrylate and methacrylate.

Examples of the (meth) acrylate having an alkyl fluoride group include 2,2,2-trifluoroethyl (meth) acrylate, 2,2,3,3,3-pentafluoropropyl (meth) acrylate, and perfluorohexyl. Ethyl (meth) acrylate can be mentioned.

Examples of the monomer having no alkyl fluoride group and having an ester group (> C = 0) include methoxypolyethylene glycol (meth) acrylate, methoxypolyethylene glycol (meth) acrylicate, phenoxypolyethylene glycol (meth) acrylate, and phenoxy. Examples thereof include (meth) acrylate of polyethylene glycol (meth) acrylate.

As the fluorine-based graft polymer, a fluoroalkyl 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) is particularly preferable.

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 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 greater than or equal to 0 or 1.
ft represents an integer of 1 or more and 7 or less.
fx represents an integer of 1 or more.

In the general formulas (FA) and (FB), ^{as the group representing R F1} , R ^F2 , R ^F3 , and R ^F4 , a hydrogen atom, a methyl group, an ethyl group, a propyl group and the like are preferable, and a hydrogen atom and a methyl group are used. More preferably, a methyl group is even more preferable.

In the general formulas (FA) and (FB), the alkylene chains (unsubstituted alkylene chains, halogen-substituted alkylene chains) representing ^{X F1} and Y ^{F1 are linear or branched alkylene chains having 1 to 10 carbon atoms.} Is preferable.
_{It is preferable that fx in} − (C fx H _2fx-1 (OH)) − representing Y ^F1 represents an integer of 1 or more and 10 or less.
It is preferable that fp, fq, fr, and fs independently represent 0 or an integer of 1 or more and 10 or less.
The fn is preferably 1 or more and 60 or less, for example.

Here, in the fluorine-based graft polymer, the ratio of the number of the structural unit represented by the general formula (FA) to the number of the structural unit represented by the general formula (FB), that is, fl: fm is 1: 9 to 9: 1. The range up to is preferable, and the range from 3: 7 to 7: 3 is more preferable.

The fluorine-based graft polymer may further have a structural unit represented by the general formula (FC) in addition to the structural unit represented by the general formula (FA) and the structural unit represented by the general formula (FB).

In the general formula (FC), ^RF5 and ^RF6 each independently represent a hydrogen atom or an alkyl group. fz represents an integer of 1 or more.

In the general formula (FC), ^{as the group representing RF5} and ^RF6 , a hydrogen atom, a methyl group, an ethyl group, a propyl group and the like are preferable, a hydrogen atom and a methyl group are more preferable, and a methyl group is further preferable.

The content ratio of the structural units represented by the general formula (FC) is the total number of structural units represented by the general formulas (FA) and (FB), that is, the ratio of fl + fm to fz (fl + fm: fz), which is 10 The range from: 0 to 7: 3 is preferable, and the range from 9: 1 to 7: 3 is more preferable.

One type of fluorine-based graft polymer may be used alone, or two or more types may be used in combination.
The content of the fluorine-based graft polymer is, for example, preferably 0.5% by mass or more and 10% by mass or less, and more preferably 1% by mass or more and 7% by mass or less with respect to the fluorine-containing resin particles.

[Perfluorooctanoic acid]
In the photoconductor according to the present embodiment, the outermost surface layer contains dispersant-adhered particles in which a fluorine-based graft polymer is adhered to the surface of fluorine-containing resin particles.
The content of perfluorooctanoic acid (also referred to as PFOA) in the dispersant-adhered particles is preferably 0 ppb or more and 25 ppb or less with respect to the total mass of the fluorine-containing resin particles.
That is, it is preferable that the dispersant-adhered particles contained in the outermost surface layer do not contain PFOA, or even if they contain PFOA, the content is suppressed.

In particular, in the case of fluorine-containing resin particles such as polytetrafluoroethylene particles, modified polytetrafluoroethylene particles, and perfluoroalkyl ether / tetrafluoroethylene copolymer particles, PFOA is used or a by-product in the production process. In many cases, the fluorine-containing resin particles contain PTFE.
Therefore, in order to suppress the content of PTOA in the dispersant-adhered particles contained in the outermost surface layer, it is preferable to use fluorine-containing resin particles in which the amount of PFOA is reduced. That is, the amount of PFOA in the fluorine-containing resin particles is also preferably 0 ppb or more and 25 ppb or less with respect to the total mass of the fluorine-containing resin particles.

Methods for reducing the amount of PFOA in fluorine-containing resin particles include pure water, alkaline water, alcohols (methanol, ethanol, isopropanol, etc.), ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.), esters (acetate). Ethyl, etc.), and other general organic solvents (toluene, tetrahydrofuran, etc.), etc., can be used to sufficiently wash the fluorine-containing resin particles. The fluorine-containing resin particles may be washed at room temperature, but the amount of PFOA in the fluorine-containing resin particles can be efficiently reduced by performing the cleaning under heating.

Here, the amount of PFOA in the dispersant-attached particles is measured by the following method.

-Sample pretreatment-
When measuring the amount of PFOA from the outermost surface layer containing the dispersant-adhered particles, the outermost surface layer is immersed in a solvent (for example, tetrahydrofuran), and a solvent (here, tetrahydrofuran) other than the dispersant-adhered particles and a substance insoluble in the solvent is used. ), The obtained solution is added dropwise to pure water, and the precipitate is filtered off. The solution containing PFOA obtained at that time is collected. Further, the insoluble matter obtained by filtration is dissolved in a solvent and then added dropwise to pure water to filter out the precipitate. The operation of collecting the solution containing PFOA obtained at that time is repeated 5 times, and the aqueous solution collected in all the operations is used as the pretreated aqueous solution.
When the amount of PFOA is measured from the fluorine-containing resin particles themselves, the fluorine-containing resin particles are subjected to the same treatment as when they are contained in the outermost surface layer to obtain a pretreated aqueous solution.

-Measurement-
Analysis of perfluorooctanesulfonic acid (PFOS) perfluorooctanesulfonic acid (PFOA) of perfluorooctanesulfonic acid in environmental water, sediment, and organisms of the pretreated aqueous solution obtained by the above means Iwate Prefectural Environment Prepare and measure the sample solution according to the method shown in the "Health Research Center".

[Surface Roughness Ra]
The surface roughness Ra of the outermost surface layer (that is, the surface roughness Ra of the photoconductor according to the present embodiment) is preferably 0.13 μm or less, preferably 0.10 μm, from the viewpoint of enhancing the surface smoothness of the photoconductor. It is more preferably 0.18 μm or less, and further preferably 0.08 μm or less.
On the other hand, as the lower limit of the surface roughness Ra of the outermost surface layer, for example, 0.05 μm or more is preferable.
In particular, when the outermost surface layer contains dispersant-adhered particles having a PFOA amount in the above range, the surface roughness Ra of the outermost surface layer is preferably 0.10 μm or less.

The surface roughness Ra is obtained by the following method.
A part of the outermost surface layer is cut out with a cutter or the like to obtain a test piece. The test piece is measured using a stylus type surface roughness measuring machine (Surfcom 1400A: manufactured by Tokyo Seimitsu Co., Ltd., etc.). The measurement conditions are based on JIS B 0601: 1994, and the evaluation length Ln = 10 mm, the reference length L = 0.8 mm, and the cutoff value = 0.8 mm.

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

The electrophotographic photosensitive member 7 may have a layer structure in which the undercoat layer 1 is not provided.
Further, the electrophotographic photosensitive member 7 may be a photosensitive member having a single-layer type photosensitive layer in which the functions of the charge generating layer 2 and the charge transporting layer 3 are integrated. In the case of a photoconductor having a single-layer type photosensitive layer, the single-layer type photosensitive layer constitutes the outermost surface layer.
Further, the electrophotographic photosensitive member 7 may be a photosensitive member having a surface protective layer on the charge transport layer 3 or the single-layer type photosensitive layer. In the case of a photoconductor having a surface protective layer, the surface protective layer constitutes the outermost surface layer.

Hereinafter, each layer of the electrophotographic photosensitive member according to the present embodiment will be described in detail. The reference numerals will be omitted.

(Conductive substrate)
Examples of the conductive substrate include metal plates containing metals (aluminum, copper, zinc, chromium, nickel, molybdenum, vanadium, indium, gold, platinum, etc.) or alloys (stainless steel, etc.), metal drums, metal belts, and the like. Can be mentioned. Examples of the conductive substrate include paper, resin film, belt and the like coated, vapor-deposited or laminated with a conductive compound (for example, conductive polymer, indium oxide, etc.), metal (for example, aluminum, palladium, gold, etc.) or alloy. Can also be mentioned. Here, "conductive" means that the volume resistivity is less than ^{10 13 Ωcm.}

When the electrophotographic photosensitive member is used in a laser printer, the surface of the conductive substrate has a center line average roughness Ra of 0.04 μm or more and 0.5 μm for the purpose of suppressing interference fringes generated when irradiating the laser beam. It is preferable that the surface is roughened below. When non-interfering light is used as the light source, 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 the unevenness of the surface of the conductive substrate.

Roughening methods include, for example, wet honing performed by suspending an abrasive in water and spraying it onto a conductive substrate, and centerless grinding in which a conductive substrate is pressed against a rotating grindstone and continuously ground. , Anodization treatment and the like.

As a method of roughening, the conductive or semi-conductive powder is dispersed in the resin without roughening the surface of the conductive substrate to form a layer on the surface of the conductive substrate. Another method is to roughen the surface with particles dispersed in the layer.

In the roughening treatment by anodic oxidation, an oxide film is formed on the surface of the conductive substrate by anodicating in an electrolyte solution using a conductive substrate made of metal (for example, made of aluminum) as an anode. Examples of the electrolyte solution include sulfuric acid solution, oxalic acid solution and the like. However, the porous anodized film formed by anodizing is chemically active as it is, is easily contaminated, and has a large resistance fluctuation depending on the environment. Therefore, for the porous anodic oxide film, the micropores of the oxide film are closed by volume expansion due to the hydration reaction in pressurized steam or boiling water (a metal salt such as nickel may be added), and more stable hydration oxidation is performed. It is preferable to perform a hole-sealing treatment to change the material.

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

The conductive substrate may be treated with an acidic treatment liquid or a boehmite treatment.
The treatment with the acidic treatment liquid is carried out as follows, for example. First, an acidic treatment liquid 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 liquid is, for example, phosphoric acid in the range of 10% by mass or more and 11% by mass or less, chromic acid in the range of 3% by mass or more and 5% by mass or less, and phosphoric acid. It is preferably in the range of 0.5% by mass or more and 2% by mass or less, and the concentration of these acids as a whole 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 film thickness of the coating is preferably 0.3 μm or more and 15 μm or less.

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

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

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

The specific surface area of the inorganic particles by the BET method is, for example, ^{preferably 10 m 2} / g or more.
The volume average particle diameter of the inorganic particles is, for example, preferably 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, and more preferably 40% by mass or more and 80% by mass or less with respect to the binder resin.

The inorganic particles may be surface-treated. As the inorganic particles, those having different surface treatments or those having different particle sizes may be mixed and used.

Examples of the surface treatment agent include a silane coupling agent, a titanate-based coupling agent, an aluminum-based coupling agent, a surfactant and the like. In particular, a silane coupling agent is preferable, and a silane coupling agent having an amino group is more preferable.

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

Two or more kinds of silane coupling agents may be mixed and used. For example, a silane coupling agent having an amino group may be used in combination with another silane coupling agent. Other silane coupling agents include, for example, vinyltrimethoxysilane, 3-methacryloxypropyl-tris (2-methoxyethoxy) silane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glyceride. Sidoxypropyltrimethoxysilane, vinyltriacetoxysilane, 3-mercaptopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, N-2- ( Aminoethyl) -3-aminopropylmethyldimethoxysilane, N, N-bis (2-hydroxyethyl) -3-aminopropyltriethoxysilane, 3-chloropropyltrimethoxysilane and the like can be mentioned, but are limited thereto. It's not a thing.

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

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

Here, it is preferable that the undercoat layer contains an electron acceptor compound (acceptor compound) together with the inorganic particles from the viewpoint of enhancing the long-term stability of the electrical characteristics and the carrier blocking property.

Examples of the electron-accepting compound include quinone compounds such as chloranyl and bromoanyl; tetracyanoquinodimethane compounds; 2,4,7-trinitrofluorenone, 2,4,5,7-tetranitro-9-fluorenone and the like. Fluolenone compounds; 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) -1,3,4 oxadiazole; xanthone compounds; thiophene compounds; 3,3', 5,5'tetra- Examples thereof 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 preferable. As the compound having an anthraquinone structure, for example, a hydroxyanthraquinone compound, an aminoanthraquinone compound, an aminohydroxyanthraquinone compound and the like are preferable, and specifically, for example, anthraquinone, alizarin, quinizarin, anthralfin, purpurin and the like are preferable.

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

Examples of the method for adhering 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 having a large shearing force, an electron-accepting compound dissolved directly or in an organic solvent is dropped and sprayed together with dry air or nitrogen gas to obtain an electron-accepting compound. This is a method of adhering to the surface of inorganic particles. When dropping or spraying the electron-accepting compound, it is preferable to carry out at a temperature equal to or lower than the boiling point of the solvent. After dropping or spraying the electron-accepting compound, baking may be further carried out at 100 ° C. or higher. The printing is not particularly limited as long as the temperature and time at which the electrophotographic characteristics can be obtained.

In the wet method, for example, by stirring, ultrasonic waves, sand mill, attritor, ball mill, etc., while dispersing inorganic particles in a solvent, an electron-accepting compound is added, stirred or dispersed, and then the solvent is removed to remove electrons. This is a method of adhering an accepting compound to the surface of inorganic particles. The solvent removing method is distilled off, for example, by filtration or distillation. After removing the solvent, baking may be further performed at 100 ° C. or higher. The printing is not particularly limited as long as the temperature and time at which the electrophotographic characteristics can be obtained. In the wet method, the water content of the inorganic particles may be removed before the electron-accepting compound is added. Examples thereof include a method of removing by stirring and heating in a solvent, and a method of removing by azeotropically boiling with a solvent. Can be mentioned.

The electron-accepting compound may be attached before or after the surface treatment with the surface treatment agent is applied to the inorganic particles, and the electron-accepting compound may be attached and the surface treatment with the surface treatment agent may be performed at the same time.

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

Examples of the binder resin used for 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 polymer compounds such as urethane resin, alkyd resin, and epoxy resin; zirconium chelate compound; titanium chelate compound; aluminum chelate compound; titanium alkoxide compound; organic titanium compound; known materials such as silane coupling agent can be mentioned.
Examples of the binder resin used for the undercoat layer include a charge-transporting resin having a charge-transporting group, a conductive resin (for example, polyaniline, etc.) and the like.

Among these, as the binder resin used for the undercoat layer, a resin insoluble in the coating solvent of the upper layer is preferable, and in particular, a urea resin, a phenol resin, a phenol-formaldehyde resin, a melamine resin, a urethane resin, and an unsaturated polyester. Thermocurable resins such as resins, alkyd resins, epoxy resins; with 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. A resin obtained by reacting with a curing agent is preferable.
When two or more of these binder resins are used in combination, the mixing ratio thereof is set as necessary.

The undercoat layer may contain various additives for improving electrical characteristics, environmental stability, and image quality.
Examples of the additive include known materials such as electron-transporting pigments such as polycyclic condensation type and azo type, zirconium chelate compound, titanium chelate compound, aluminum chelate compound, titanium alkoxide compound, organic titanium compound, and silane coupling agent. Be done. The silane coupling agent is used for surface treatment of inorganic particles as described above, but may be further 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-. Glycydoxypropyltrimethoxysilane, vinyltriacetoxysilane, 3-mercaptopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, N-2- (Aminoethyl) -3-aminopropylmethyldimethoxysilane, N, N-bis (2-hydroxyethyl) -3-aminopropyltriethoxysilane, 3-chloropropyltrimethoxysilane and the like can be mentioned.

Examples of the zirconium chelate compound include zirconium butoxide, zirconium acetoacetate, zirconium triethanolamine, acetylacetonate zirconium butoxide, zirconium acetate zirconium butoxide, zirconium acetate, zirconium oxalate, zirconium lactate, zirconium phosphonate, zirconium octanate, Examples thereof include zirconium naphthenate, zirconium laurate, zirconium stearate, zirconium isostearate, zirconium methacrylate butoxide, stearate zirconium butoxide, and isosterate zirconium butoxide.

Examples of the titanium chelate compound include tetraisopropyl titanate, tetranormal 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 diisopropyrate, aluminum butyrate, diethylacetacetate aluminum diisopropirate, aluminum tris (ethylacetacetate) 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 for suppressing moire images. It should be 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.

The formation of the undercoat layer is not particularly limited, and a well-known forming method is used. For example, a coating film of a coating liquid for forming an undercoat layer in which the above components are added to a solvent is formed, and the coating film is dried. Then, if necessary, heat it.

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

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

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

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

(Middle layer)
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 a resin. Examples of the resin used for the intermediate 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, methacrylic resin, and acrylic resin. Examples thereof include polymer 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 for the intermediate layer include organometallic compounds containing metal atoms such as zirconium, titanium, aluminum, manganese, and silicon.
The compounds used for 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.

The formation of the intermediate layer is not particularly limited, and a well-known forming method is used. For example, a coating film of an intermediate layer forming coating liquid in which the above components are added to a solvent is formed, and the coating film is dried and required. It is performed by heating according to the above.
As a coating method for forming the intermediate layer, ordinary methods such as a dip coating method, a push-up coating method, a wire bar coating method, a spray coating method, a blade coating method, a knife coating method, and a curtain coating method are used.

The film thickness of the intermediate layer is preferably set in the range of 0.1 μm or more and 3 μm or less. The intermediate layer may be used as the undercoat 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 vapor deposition layer of a charge generation material. The thin-film deposition layer of the charge generating material is suitable when a non-interfering light source such as an LED (Light Emitting Diode) or an organic EL (Electro-Luminescence) image array is used.

Examples of the charge generating material include azo pigments such as bisazo and trisazo; condensed ring aromatic pigments such as dibromoanthanthron; perylene pigment; pyrolopyrrolop pigment; phthalocyanine pigment; zinc oxide; and tricyclic selenium.

Among these, in order to correspond to laser exposure in the near infrared region, it is preferable to use a metal phthalocyanine pigment or a metal-free phthalocyanine pigment as the charge generating material. 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 .; JP-A-5. Dichlorostin phthalocyanine disclosed in JP-A-140472, JP-A-5-140473, etc .; Titanyl phthalocyanine disclosed in JP-A-4-1809873, etc. is more preferable.

On the other hand, in order to support laser exposure in the near-ultraviolet region, as a charge generating material, a fused ring aromatic pigment such as dibromoanthanthrone; a thioindigo pigment; a porphyrazine compound; zinc oxide; a trigonal selenium; The bisazo pigments disclosed in JP-A-2004-78147 and JP-A-2005-181992 are preferable.

The above charge generating material may also be used when using a non-interfering light source such as an LED or an organic EL image array having a center wavelength of light emission of 450 nm or more and 780 nm or less, but from the viewpoint of resolution, the photosensitive layer is 20 μm or less. When used in a thin film of the above, the electric field strength in the photosensitive layer becomes high, and an image defect called a so-called black spot, which is a decrease in charge due to charge injection from the substrate, is likely to occur. This becomes remarkable when a charge generating material such as a trigonal selenium or a phthalocyanine pigment, which is a p-type semiconductor and tends to generate a dark current, is used.

On the other hand, when an n-type semiconductor such as a fused ring aromatic pigment, a perylene pigment, or an azo pigment is used as the charge generating material, dark current is unlikely to be generated, and even a thin film can suppress image defects called black spots. .. Examples of the n-type charge generating material include compounds (CG-1) to (CG-27) described in paragraphs [0288] to [0291] of JP2012-1552282. It is not limited.
The n-type is determined by using the normally used time-of-flight method, and is determined by the polarity of the flowing photocurrent, and the n-type is one in which electrons are more easily flowed as carriers than holes.

The binder resin used for the charge generation layer is selected from a wide range of insulating resins, and the binder resin is 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 (hypercondensate of bisphenol and aromatic divalent carboxylic acid, etc.), polycarbonate resin, polyester resin, phenoxy resin, vinyl chloride-vinyl acetate copolymer, and the like. Examples thereof 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 property" means that the volume resistivity is 10 ¹³ Ωcm or more.
These binder resins are used alone or in admixture of two or more.

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

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

The formation of the charge generation layer is not particularly limited, and a well-known formation method is used. For example, a coating film of a coating liquid for forming a charge generation layer in which the above components are added to a solvent is formed, and the coating film is dried. Then, if necessary, heat it. The charge generation layer may be formed by vapor deposition of a charge generation material. The formation of the charge generation layer by thin film deposition is particularly suitable when a condensed ring aromatic pigment or a perylene pigment is used as the charge generation material.

Solvents for preparing the coating liquid for forming the charge generation layer include methanol, ethanol, n-propanol, n-butanol, benzyl alcohol, methyl cellsolve, ethyl cell solution, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, n acetate. -Butyl, dioxane, tetrahydrofuran, methylene chloride, chloroform, chlorobenzene, toluene and the like can be mentioned. These solvents may be used alone or in admixture of two or more.

As a method of dispersing particles (for example, a charge generating material) in a coating liquid for forming a charge generating layer, for example, a media disperser such as a ball mill, a vibrating ball mill, an attritor, a sand mill, a horizontal sand mill, a stirrer, or an ultrasonic disperser. , Roll mills, high pressure homogenizers and other medialess dispersers are used. Examples of the high-pressure homogenizer include a collision method in which a dispersion liquid is dispersed by a liquid-liquid collision or a liquid-wall collision in a high-pressure state, and a penetration method in which a dispersion liquid is dispersed by penetrating a fine flow path in a high-pressure state.
At the time of this dispersion, it is effective to set the average particle size of the charge generating material in the coating liquid for forming the charge generating layer to 0.5 μm or less, preferably 0.3 μm or less, and more preferably 0.15 μm or less. ..

As a method of applying the coating liquid for forming the charge generation layer on the undercoat layer (or on the intermediate layer), for example, a blade coating method, a wire bar coating method, a spray coating method, a dipping coating method, a bead coating method, and an air knife coating method. Examples thereof include ordinary methods such as a method and a curtain coating method.

The film thickness of the charge generation layer is preferably set within the 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 polymer charge transport material.

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

As the charge transport material, 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 from the viewpoint of charge mobility.

In the structural formulas ^{(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 ( ^RT7 ) ( ^RT8 ) is shown. ^RT4 , ^RT5 , ^RT6 , ^RT7 , and ^RT8 each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group.
Examples of the substituent of each of the above groups include a halogen atom, an alkyl group having 1 or more and 5 or less carbon atoms, and an alkoxy group having 1 or more and 5 or less carbon atoms. Further, examples of the substituent of each of the above groups include a substituted amino group substituted with an alkyl group having 1 or more carbon atoms and 3 or less carbon atoms.

In the structural formula (a-2), ^RT91 and ^RT92 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. To ^{R T101,} R T102, R ^T111 and ^{R T112} are each independently a halogen atom, 1 to 5 carbon atoms in the alkyl group, 1 to 5 of the alkoxy group carbon atoms, a substituted alkyl group having 1 to 2 carbon atoms The amino group, substituted or unsubstituted aryl group, -C ( ^RT12 ) = C ( ^RT13 ) ( ^RT14 ), or -CH = CH-CH = C ( ^RT15 ) ( ^RT16 ) is shown. ^RT12 , ^RT13 , ^RT14 , ^RT15 and ^RT16 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 the substituent of each of the above groups include a halogen atom, an alkyl group having 1 or more and 5 or less carbon atoms, and an alkoxy group having 1 or more and 5 or less carbon atoms. Further, examples of the substituent of each of the above groups include a substituted amino group substituted with an alkyl group having 1 or more carbon atoms 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 =". C ^(R T7) triarylamine derivative having ^{(R T8)} ", and benzidine derivatives having" ^{-CH = CH-CH = C (} R T15) (R T16) ", preferable from the viewpoint of charge mobility.

As the polymer charge transport material, known materials having charge transport 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 preferable. The polymer charge transport material may be used alone or in combination with a binder resin.

The binder resin used for the charge transport layer is 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 -Vinylcarbazole, polysilane, etc. can be mentioned. Among these, as the binder resin, a polycarbonate resin or a polyarylate resin is preferable. One of these binder resins is used alone or in combination of two or more.
The blending ratio of the charge transport material and the binder resin is preferably 10: 1 to 1: 5 in terms of mass ratio.

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

The formation of the charge transport layer is not particularly limited, and a well-known forming method is used. For example, a coating film of a coating liquid for forming a charge transport layer in which the above components are added to a solvent is formed, and the coating film is dried. , By heating as needed.

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

As a method of dispersing particles (for example, fluorine-containing resin particles) in the coating liquid for forming a charge transport layer, for example, a media disperser such as a ball mill, a vibrating ball mill, an attritor, a sand mill, a horizontal sand mill, stirring, ultrasonic dispersion, etc. Medialess dispersers such as machines, roll mills, and high-pressure homogenizers are used. Examples of the high-pressure homogenizer include a collision method in which a dispersion liquid is dispersed by a liquid-liquid collision or a liquid-wall collision in a high-pressure state, and a penetration method in which a dispersion liquid is dispersed by penetrating a fine flow path in a high-pressure state.

The coating methods for applying the coating liquid for forming a charge transport layer onto the charge generating layer include a blade coating method, a wire bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method, and a curtain. Examples include a normal method such as a coating method.

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

(Protective layer)
The protective layer is provided on the photosensitive layer as needed. The protective layer is provided, for example, for the purpose of preventing a chemical change of the photosensitive layer during charging and further improving the mechanical strength of the photosensitive layer.
Therefore, as the protective layer, it is preferable to apply a layer composed of a cured film (crosslinked film). 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 (that is, a polymer or cross-linking of the reactive group-containing charge-transporting material). Layer including body)
2) A layer composed of a cured film of a composition containing a non-reactive charge transport material and a reactive group-containing non-charge transport material having a reactive group without a charge transport skeleton (that is,). A layer containing a non-reactive charge transport material and a polymer or crosslinked product of the reactive group-containing non-charge transport material)

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

The chain-growth group is not particularly limited as long as it is a functional group capable of radical polymerization, and is, for example, a functional group having a group containing at least a carbon double bond. Specific examples thereof include a vinyl group, a vinyl ether group, a vinyl thioether group, a styryl group (vinyl phenyl group), an acryloyl group, a methacryloyl group, and a group containing at least one selected from derivatives thereof. Among them, a group containing at least one selected from a vinyl group, a styryl group (vinylphenyl group), an acryloyl group, a methacryloyl group, and derivatives thereof as the chain-growth polymerizable group because of its excellent reactivity. Is preferable.

The charge-transporting skeleton of the reactive group-containing charge-transporting material is not particularly limited as long as it has a known structure in the electrophotographic photosensitive member, and is, for example, a triarylamine-based compound, a benzidine-based compound, a hydrazone-based compound, or the like. It is a skeleton derived from a nitrogen-containing hole-transporting compound of the above, and has a structure conjugated with a nitrogen atom. Among these, the triarylamine skeleton is preferable.

The reactive group-containing charge transport material having the reactive group and the charge transport skeleton, the non-reactive charge transport material, and the reactive group-containing non-charge transport material may be selected from well-known materials.

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

The formation of the protective layer is not particularly limited, and a well-known forming method is used. For example, a coating film of a coating liquid for forming a protective layer in which the above components are added to a solvent is formed, and the coating film is dried. If necessary, it is cured by heating or the like.

As the solvent for preparing the coating liquid for forming the protective layer, 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-based solvent such as dioxane; cellosolve-based solvent such as ethylene glycol monomethyl ether; alcohol-based solvent such as isopropyl alcohol and butanol. These solvents are used alone or in combination of two or more.
The coating liquid for forming the protective layer may be a solvent-free coating liquid.

As a method of applying the coating liquid for forming a protective layer on a photosensitive layer (for example, a charge transport layer), a dip coating method, a push-up coating method, a wire bar coating method, a spray coating method, a blade coating method, a knife coating method, and a curtain coating method are used. Ordinary methods such as law can be mentioned.

The film thickness of the protective layer is preferably set within the 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 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. These materials are the same as the materials described in 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 with respect to the total solid content. .. Further, the content of the charge transport material in the single-layer photosensitive layer is preferably 5% by mass or more and 50% by mass or less with respect to the total solid content.
The method for forming the single-layer photosensitive layer is the same as the method for forming the charge generation layer and the charge transport layer.
The film thickness of the single-layer 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 photosensitive member, a charging means for charging the surface of the electrophotographic photosensitive member, and an electrostatic latent image forming on the surface of the charged electrophotographic photosensitive member. Means, a developing means for developing an electrostatic latent image formed on the surface of an electrophotographic photosensitive member with a developer containing toner to form a toner image, and a transfer means for transferring the toner image to the surface of a recording medium. To be equipped. Then, as the electrophotographic photosensitive member, the electrophotographic photosensitive member according to the present embodiment is applied.

The image forming apparatus according to the present embodiment is an apparatus provided with fixing means for fixing the toner image transferred to the surface of the recording medium; direct transfer for directly transferring the toner image formed on the surface of the electrophotographic photosensitive member to the recording medium. Device of the method; Intermediate transfer in which the toner image formed on the surface of the electrophotographic photosensitive member is primarily transferred to the surface of the intermediate transfer body, and the toner image transferred to the surface of the intermediate transfer body is secondarily transferred to the surface of the recording medium. Device of the method; A device equipped with a cleaning means for cleaning the surface of the electrophotographic photosensitive member after the transfer of the toner image and before charging; the surface of the electrophotographic photosensitive member is irradiated with xerographic light after the transfer of the toner image and before charging. A device provided with a static elimination means for removing static electricity; a well-known image forming device such as a device provided with an electrophotographic photosensitive member heating member for raising the temperature of the electrophotographic photosensitive member and reducing the relative temperature is applied.

In the case of an intermediate transfer type apparatus, the transfer means is, for example, a primary transfer body in which a toner image is transferred to the surface and a primary transfer of a toner image formed on the surface of an electrophotographic photosensitive member to the surface of the intermediate transfer body. A configuration having a transfer means and a secondary transfer means for secondary transfer of the toner image transferred to the surface of the intermediate transfer body to the surface of the recording medium is applied.

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

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

Hereinafter, an example of the image forming apparatus according to the present embodiment will be shown, but the present invention is not limited thereto. The main parts shown in the figure will be described, and the other parts will be omitted.

FIG. 2 is a schematic configuration diagram showing an example of an image forming apparatus according to the present embodiment.
As shown in FIG. 2, the image forming apparatus 100 according to the present embodiment includes a process cartridge 300 including an electrophotographic photosensitive member 7, an exposure apparatus 9 (an example of an electrostatic latent image forming means), and a transfer apparatus 40 (primary). A transfer device) and an intermediate transfer body 50 are provided. In the image forming apparatus 100, the exposure apparatus 9 is arranged at a position where the electrophotographic photosensitive member 7 can be exposed to the electrophotographic photosensitive member 7 through the opening of the process cartridge 300, and the transfer apparatus 40 is arranged through the intermediate transfer body 50 to expose the electrophotographic photosensitive member 7. The intermediate transfer member 50 is arranged at a position facing the electrophotographic photosensitive member 7, and a part of the intermediate transfer member 50 is arranged in contact with the electrophotographic photosensitive member 7. Although not shown, it also has a secondary transfer device that transfers the toner image transferred to the intermediate transfer body 50 to a recording medium (for example, paper). 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 has an electrophotographic photosensitive member 7, a charging device 8 (an example of charging means), a developing device 11 (an example of developing means), and a cleaning device 13 (an example of cleaning means) integrated in a housing. Supports. The cleaning device 13 has a cleaning blade (an example of a cleaning member) 131, and the cleaning blade 131 is arranged so as to come into contact with the surface of the electrophotographic photosensitive member 7. The cleaning member may be a conductive or insulating fibrous member instead of the mode of the cleaning blade 131, and may be used alone or in combination with the cleaning blade 131.

In addition, in FIG. 2, as an image forming apparatus, a fibrous member 132 (roll shape) that supplies a lubricant 14 to the surface of an electrophotographic photosensitive member 7 and a fibrous member 133 (flat brush shape) that assists cleaning are shown. Examples are shown, but these are arranged as needed.

Hereinafter, each configuration of the image forming apparatus according to the present embodiment will be described.

-Charging device-
As the charging device 8, for example, a contact-type charging device using a conductive or semi-conductive charging roller, a charging brush, a charging film, a charging rubber blade, a charging tube, or the like is used. Further, a non-contact type roller charger, a scorotron charger using corona discharge, a corotron charger, or the like, which is known per se, is also used.

-Exposure device-
Examples of the exposure apparatus 9 include an optical system device that exposes light such as a semiconductor laser beam, an LED light, and a liquid crystal shutter light on the surface of the electrophotographic photosensitive member 7 in a predetermined image pattern. The wavelength of the light source is within the spectral sensitivity region of the electrophotographic photosensitive member. As the wavelength of the semiconductor laser, the near infrared having an oscillation wavelength in the vicinity of 780 nm is the mainstream. However, the wavelength is not limited to this, and a laser having an oscillation wavelength in the 600 nm range or a laser having an oscillation wavelength of 400 nm or more and 450 nm or less may be used as a blue laser. Further, a surface emitting type laser light source capable of outputting a multi-beam is also effective for forming a color image.

-Developer-
Examples of the developing device 11 include a general developing device that develops by contacting or not contacting a developing agent. The developing device 11 is not particularly limited as long as it has the above-mentioned functions, and is selected according to the purpose. For example, a known developer having a function of adhering a one-component developer or a two-component developer to the electrophotographic photosensitive member 7 using a brush, a roller, or the like can be mentioned. Of these, those using a developing roller in which the developing agent is held on the surface are preferable.

The developer used in the developing apparatus 11 may be a one-component developer using only toner or a two-component developer containing toner and a carrier. Further, the developer may be magnetic or non-magnetic. Well-known developer is applied.

-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 adopted.

-Transfer device-
Examples of the transfer device 40 include contact-type transfer chargers using belts, rollers, films, rubber blades, etc., scorotron transfer chargers using corona discharge, and transfer chargers known per se, such as corotron transfer chargers. Can be mentioned.

-Intermediate transcript-
As the intermediate transfer body 50, a belt-shaped one (intermediate transfer belt) containing semi-conductive polyimide, polyamide-imide, polycarbonate, polyarylate, polyester, rubber, or the like is used. Further, as the form of the intermediate transfer body, a drum-shaped one may be used in addition to the belt-shaped one.

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 type 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 body 50, and one electrophotographic photosensitive member is used for each color. The image forming apparatus 120 has the same configuration as the image forming apparatus 100 except that it is a tandem type.

Hereinafter, examples of the present invention will be described, but the present invention is not limited to the following examples. In addition, "part" or "%" is based on mass unless otherwise specified.

<Manufacturing of fluorine-containing resin particles>
(Manufacture of Fluorine-Containing Resin Particles (1))
Fluorine-containing resin particles (1) were produced as follows.
100 parts by mass of commercially available homopolytetrafluoroethylene fine powder (standard specific gravity 2.175 measured according to ASTM D 4895 (2004)) and 2.8 parts by mass of ethanol as an additive are collected in a barrier nylon bag. Collected. Then, it was irradiated with cobalt-60γ rays at room temperature in air at 160 kGy to obtain a low molecular weight polytetrafluoroethylene powder. The obtained powder was pulverized to obtain fluorine-containing resin particles (1).

(Manufacture of Fluorine-Containing Resin Particles (2))
In the production of the fluorine-containing resin particles (1), 100 parts by mass of the obtained fluorine-containing resin particles (1) and 500 parts by mass of methanol are mixed and washed with a stirrer at 300 rpm for 10 minutes while irradiating them with ultrasonic waves. , The supernatant was decanted. After repeating this operation four times, the residue filter was dried at 70 ° C. for 24 hours in a blower dryer to produce fluorine-containing resin particles (2).

(Manufacture of Fluorine-Containing Resin Particles (3))
In an autoclave equipped with a stirrer, 3.2 liters of deionized water, 5.0 g of ammonium perfluorooctanoate, and 120 g of paraffin wax (manufactured by Nippon Petroleum Co., Ltd.) as an emulsion stabilizer were charged, and TFE was added three times with nitrogen. The system was replaced twice with (tetrafluoroethylene) to remove oxygen. Then, the internal pressure was adjusted to 0.9 MPa with TFE, and the internal temperature was maintained at 80 ° C. while stirring at 250 rpm. Next, 20 ml of an aqueous solution in which 15 mg of ammonium persulfate was dissolved in deionized water and 20 ml of an aqueous solution in which 200 mg of succinate peroxide was dissolved in deionized water were charged into the system to start the reaction. During the reaction, TFE was continuously supplied so that the temperature in the system was kept at 80 ° C. and the internal pressure of the autoclave was always kept at 0.9 MPa. When the amount of TFE consumed in the reaction reached 1100 g after the initiator was added, the supply and stirring of TFE was stopped, the inside of the autoclave was released to normal pressure, and the reaction was terminated. After allowing to cool, the supernatant paraffin wax was removed, the emulsion was transferred to a stainless steel container equipped with a stirrer, and 1.5 L of deionized water was added to adjust the temperature to 15 ° C. To this, 100 g of an aqueous solution in which 20 g of ammonium carbonate and 2 g of triethylamine were dissolved was added, and the mixture was stirred at 450 rpm to aggregate the fluorine-containing resin particles, and then the particles were separated by centrifugation. Next, 4 L of methanol was added, and the mixture was stirred and washed for 30 minutes, and then filtered to wash the fluorine-containing resin particles. After repeating this washing operation four times, the obtained fluorine-containing fine particles were dried at 70 ° C. for 24 hours in a blower dryer to produce fluorine-containing resin particles (3).

The number average particle diameters of the obtained primary particles of the fluorine-containing resin particles (1) to (3) were measured by the method described above.
The results are shown in Table 1.

<Manufacturing of fluorine-based graft polymer>
(Manufacture of Fluorine-based Graft Polymer (1))
The fluorine-based graft polymer (1) was synthesized as follows.
Put 5 parts by mass of methyl isobutyl ketone into a 500 mL reaction vessel equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen gas inlet, and stir to bring the solution temperature in the reaction vessel to 80 ° C. under a nitrogen gas atmosphere. Maintained. 9 parts by mass of perfluorohexyl ethyl acrylate, 21 parts by mass of macromonomer AA-6 (manufactured by Toa Synthetic Co., Ltd.), 1.6 parts by mass of perhexyl O (manufactured by Nichiyu Co., Ltd.) as a polymerization initiator, 45 parts by mass of methyl isobutyl ketone. The mixed solution of the above was added dropwise into the reaction vessel using a syringe dropping pump over 2 hours. After completion of the dropping, stirring was continued for another 2 hours, and then the solution temperature was raised to 90 ° C. and the mixture was further stirred for 2 hours.
400 ml of methanol was added dropwise to the methyl isobutyl ketone resin solution obtained after the reaction to precipitate a fluorine-based graft polymer. The precipitated solid content was filtered off and dried to obtain a fluorine-based graft polymer (1).

(Manufacturing of Fluorine-based Graft Polymer (2))
In the synthesis of the fluorinated graft polymer (1), the fluorinated graft was synthesized in the same manner as the fluorinated graft polymer (1) except that the amount of perhexyl O was changed from 1.6 parts by mass to 0.4 parts by mass. The polymer (2) was obtained.

(Manufacturing of Fluorine-based Graft Polymer (3))
In the synthesis of the fluorinated graft polymer (1), the fluorinated graft was synthesized in the same manner as the fluorinated graft polymer (1) except that the amount of perhexyl O was changed from 1.6 parts by mass to 0.25 parts by mass. The polymer (3) was obtained.

(Manufacture of Fluorine-based Graft Polymer (4))
In the synthesis of the fluorinated graft polymer (1), the fluorinated graft was synthesized in the same manner as the fluorinated graft polymer (1) except that the amount of perhexyl O was changed from 1.6 parts by mass to 0.19 parts by mass. The polymer (4) was obtained.

(Manufacture of Fluorine-based Graft Polymer (5))
In the synthesis of the fluorinated graft polymer (1), the fluorinated graft was synthesized in the same manner as the fluorinated graft polymer (1) except that the amount of perhexyl O was changed from 1.6 parts by mass to 0.7 parts by mass. The polymer (5) was obtained.

(Manufacture of Fluorine-based Graft Polymer (6))
In the synthesis of the fluorinated graft polymer (1), the fluorinated graft was synthesized in the same manner as the fluorinated graft polymer (1) except that the amount of perhexyl O was changed from 1.6 parts by mass to 0.55 parts by mass. The polymer (6) was obtained.

The weight average molecular weights of the obtained fluorine-based graft polymers (1) to (6) were measured by the same method as in the method for obtaining the molecular weight distribution curve described above.
The results are shown in Table 2.

<Example 1>
The photoconductor was manufactured as follows.
(Preparation of undercoat layer)
Zinc oxide: (Average particle size 70 nm: manufactured by Teika Co., Ltd .: specific surface area value 15 m ² / g) 100 parts are stirred and mixed with 500 parts of tetrahydrofuran, and 1.3 parts of a silane coupling agent (KBM503: manufactured by Shin-Etsu Chemical Co., Ltd.) is added. It was added and stirred for 2 hours. Then, toluene was distilled off under reduced pressure and baked 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 in which 0.6 part of Arizarin was dissolved in 50 parts of tetrahydrofuran was added, and the mixture was stirred at 50 ° C. for 5 hours. Then, the zinc oxide to which alizarin was added was filtered off by vacuum filtration, and further dried under reduced pressure at 60 ° C. to obtain zinc oxide to which alizarin was added.
60 parts of this alizarin-added zinc oxide, curing agent (blocked isocyanate Sumijour 3175, manufactured by Sumitomo Bavarian Urethane): 13.5 parts, butyral resin (Eslek BM-1, manufactured by Sekisui Chemical Co., Ltd.) 15 parts and methyl ethyl ketone 85 parts And were mixed to obtain a mixed solution. 38 parts of this mixed solution and 25 parts of methyl ethyl ketone were mixed and dispersed with a sand mill for 2 hours using 1 mmφ glass beads to obtain a dispersion liquid.
Dioctyltin dilaurate: 0.005 parts and silicone resin particles (Tospearl 145, Momentive Performance Materials Japan LLC): 45 parts were added to the obtained dispersion as a catalyst to obtain a coating liquid for the undercoat layer. It was. This coating liquid was applied onto an aluminum substrate having a diameter of 47 mm, a length of 357 mm, and a wall thickness of 1 mm by a dip coating method, and dried and cured at 170 ° C. for 30 minutes to obtain an undercoat layer having a thickness of 25 μm.

(Preparation of charge generation layer)
Positions where the Bragg angle (2θ ± 0.2 °) of the X-ray diffraction spectrum using Cuqα characteristic X-ray as a charge generating substance is at least 7.3 °, 16.0 °, 24.9 °, 28.0 ° A mixture consisting of 15 parts by mass of hydroxygallium phthalocyanine having a diffraction peak, 10 parts by mass of a vinyl chloride / vinyl acetate copolymer resin (VMCH, manufactured by Nippon Unicar Co., Ltd.) as a binder resin, and 200 parts by mass of n-butyl acetate. , Using glass beads having a diameter of 1 mmφ, the mixture was stirred and dispersed in a sand mill for 4 hours. 175 parts by mass of n-butyl acetate and 180 parts by mass of methyl ethyl ketone were added to the obtained dispersion liquid, and the mixture was stirred to obtain a coating liquid for forming a charge generation layer. This coating liquid for forming a charge generation layer was immersed and coated on the undercoat layer. Then, it was dried at 140 ° C. for 10 minutes to form a charge generation layer having a film thickness of 0.2 μm.

(Preparation of charge transport layer)
40 parts by mass of the charge transport agent (HT-1) having the following structure, 8 parts by mass of the charge transport agent (HT-2) having the following structure, and 52 parts by mass of the polycarbonate resin (A) (viscosity average molecular weight: 50,000) having the following structure. Was dissolved in 800 parts by mass of tetrahydrofuran, and in this solution, fluorine-containing resin particles (3): 8 parts by mass, fluorine-based graft polymer (1): 0.08 parts by mass, and fluorine-based graft polymer (6). ): 0.32 parts by mass was added. Then, this solution was dispersed by a homogenizer (manufactured by IKA: Ultratarax) at 5500 rpm for 2 hours to obtain a coating liquid for forming a charge transport layer. This coating liquid was applied onto the above-mentioned charge generation layer. Then, it was dried at 140 ° C. for 40 minutes to form a charge transport layer having a film thickness of 28 μm. This is referred to as an electrophotographic photosensitive member 1.

<Examples 2 to 15>
According to Table 3, the photoconductor was prepared in the same manner as in Example 1 except that the amount of the fluorine-containing resin particles and the type and amount of the fluorine-based graft polymer to be blended in the coating liquid for forming the charge transport layer were appropriately changed. Was produced.

<Comparative Examples 1 to 4>
According to Table 3, a photoconductor was prepared in the same manner as in Example 1 except that the type and amount of the fluorine-based graft polymer to be blended in the coating liquid for forming the charge transport layer were appropriately changed.

<Examples 16 to 31>
According to Table 4, the types of the fluorine-containing resin particles and the types and amounts of the fluorine-based graft polymers to be blended in the coating liquid for forming the charge transport layer were appropriately changed in the same manner as in Example 1. A photoconductor was prepared.

<Comparative Examples 5 to 10>
According to Table 4, the types of the fluorine-containing resin particles and the types and amounts of the fluorine-based graft polymers to be blended in the coating liquid for forming the charge transport layer were appropriately changed in the same manner as in Example 1. A photoconductor was prepared.

<Evaluation>
[Evaluation of dispersibility of fluorine-containing resin particles in the coating liquid for forming a charge transport layer]
The dispersibility of the fluorine-containing resin particles in the coating liquid for forming the charge transport layer used in each example was evaluated for the following two. The results are shown in Tables 3 and 4.

(1) Coarse particle ratio before dispersion Using a particle size distribution measuring device Mastersizer3000 manufactured by Malvern Panasonic Co., Ltd. and tetrahydrofuran as a measurement solvent, a fluorine-containing resin particle-containing liquid before dispersion by a homogenizer in "Preparation of charge transport layer" The measurement was performed to determine the ratio of coarse particles of 100 μm or more (specifically, the ratio of the number of coarse particles to all particles). The ratio of the obtained coarse particles (hereinafter referred to as the coarse particle ratio) was evaluated based on the following evaluation criteria.
-Evaluation criteria-
A: Coarse particle ratio is more than 10% B: Coarse particle ratio is more than 0% and 5% or less C: Coarse particle ratio is more than 5% and 10% or less D: Coarse particle ratio is more than 10%

(2) Stability of dispersed particles The coating liquid for forming a charge transport layer obtained by the above method is placed in a glass bottle having a capacity of about 200 mL, sealed, and rotated together with the glass bottle for 20 hours using a wave rotor. After this treatment, the particle size distribution of the coating liquid for forming the charge transport layer was measured using a particle size distribution measuring device Mastersizer 3000 manufactured by Malvern Panasonic, and the average particle size (median diameter) was calculated. Using the obtained average particle size, the stability of the dispersed particles was evaluated according to the following evaluation criteria.
-Evaluation criteria-
A: Average grain shape is 2 μm or less B: Average grain shape is more than 2 μm and 2.5 μm or less C: Average grain shape is more than 2.5 μm and 3 μm or less D: Average grain shape is more than 3 μm

[Measurement of molecular weight distribution curve]
For the photoconductors obtained in each example, the molecular weight distribution curve of the fluorine-based graft polymer contained in the charge transport layer, which is the outermost surface layer, was obtained by the method described above. Based on the obtained molecular weight distribution curve, the molecular weights M1 and M2 and the peak areas S1 and S2 were determined. The results are shown in Tables 3 and 4.
The peak areas S1 and S2 indicate the proportions of the peak areas S1 and S2 when the total of the peak areas S1 and the peak areas S2 is set to "1".

[Measurement of the amount of PFOA]
For the photoconductors obtained in each example, the amount of PFOA in the dispersant-attached particles in the charge transport layer, which is the outermost surface layer, was measured by the method described above. The results are shown in Tables 3 and 4.

[Evaluation of dispersibility of fluorine-containing resin particles in the outermost surface layer]
Similar to the method for measuring the number average particle size of the fluorine-containing resin particles described above, the cross section of the charge transport layer (that is, the outermost surface layer) of the photoconductor was observed with an SEM (scanning electron microscope) at a magnification of 5000 times. The ratio of the particles existing as the primary particles among the fluorine-containing resin particles existing in the obtained SEM image was calculated. Using the ratio of the obtained primary particles, the dispersibility of the fluorine-containing resin particles in the outermost surface layer was evaluated according to the following evaluation criteria. The results are shown in Tables 3 and 4.
-Evaluation criteria-
A: No agglomerated particles and all are primary particles B: Partially present agglomerated particles of 3 μm or less C: Partially present of agglomerated particles exceeding 3 μm and 5 μm or less D: Strong agglomeration exceeding 5 μm Commonly seen

[Evaluation of surface smoothness]
The surface roughness Ra of the photoconductor obtained in each example (that is, the surface roughness Ra of the charge transport layer which is the outermost surface layer) was measured by the method described above, and the surface smoothness was measured according to the following evaluation criteria. Was evaluated. The results are shown in Tables 3 and 4.
-Evaluation criteria-
A: Ra is 0.8 μm or less and has very high surface smoothness.
B: Ra is more than 0.8 μm and 0.10 μm or less, and has high surface smoothness.
C: Ra is more than 0.10 μm and 0.13 μm or less, and the surface smoothness is within a practically acceptable range.
D: Ra exceeds 0.13 μm, the surface smoothness is low, and practical problems occur.

From the above results, it can be seen that the photoconductor of this example has higher surface smoothness than the photoconductor of the comparative example, regardless of which of the fluorine-containing resin particles (1) to (3) is used.

1 Undercoat layer, 2 charge generation layer, 3 charge transport layer, 4 conductive substrate, 7 electrophotographic photosensitive member, 8 charging device, 9 exposure device, 11 developing device, 13 cleaning device, 14 lubricant, 40 transfer device, 50 Intermediate transfer member, 100 Image forming apparatus, 120 Image forming apparatus, 131 Cleaning blade, 132 Fibrous member (roll type), 133 Fibrous member (flat brush type), 300 Process cartridge

Claims (7)

It has a conductive substrate and a photosensitive layer provided on the conductive substrate.
The outermost surface layer contains fluorine-containing resin particles and a fluorine-based graft polymer having an alkyl fluoride group.
The peak area of the peak P1 having two or more peaks in the molecular weight distribution curve of the fluorine-based graft polymer and the minimum molecular weight in the molecular weight distribution curve of the fluorine-based graft polymer is S1, and the molecular weight is An electrophotographic photosensitive member satisfying the relationship of S1 ≦ S2, where S2 is the peak area of the maximum peak P2. In the molecular weight distribution curve of the fluorine-based graft polymer, when the molecular weight of the maximum point of the peak P1 having the minimum molecular weight is M1 and the molecular weight of the maximum point of the peak P2 having the maximum molecular weight is M2, M1 <M2 × 0 The electrophotographic photosensitive member according to claim 1, which satisfies the relationship of .5. The electrophotographic photosensitive member according to claim 1 or 2, wherein the molecular weight M2 is 50,000 or more and 200,000 or less. The outermost surface layer contains dispersant-adhered particles in which the fluorine-based graft polymer is adhered to the surface of the fluorine-containing resin particles, and the content of perfluorooctanoic acid in the dispersant-adhered particles is the amount of the fluorine-containing resin particles. The electrophotographic photosensitive member according to any one of claims 1 to 3, which is 0 ppb or more and 25 ppb or less with respect to the total mass. The electrophotographic photosensitive member according to claim 4, wherein the arithmetic average roughness Ra of the outermost surface layer is 0.13 μm or less. The electrophotographic photosensitive member according to any one of claims 1 to 5 is provided.
A process cartridge that can be attached to and detached from the image forming device. The electrophotographic photosensitive member according to any one of claims 1 to 5.
A charging means for charging the surface of the electrophotographic photosensitive member and
An electrostatic latent image forming means for forming an electrostatic latent image on the surface of the charged electrophotographic photosensitive member,
A developing means for developing an electrostatic latent image formed on the surface of the electrophotographic photosensitive member with a developer containing toner to form a toner image, and a developing means.
A transfer means for transferring the toner image to the surface of a recording medium, and
An image forming apparatus comprising.

Images