CN110609455A

CN110609455A - Polytetrafluoroethylene particle, composition, layered material, electrophotographic photoreceptor, process cartridge, and image forming apparatus

Info

Publication number: CN110609455A
Application number: CN201811274599.2A
Authority: CN
Inventors: 山田涉; 中村隆宏; 须田信吾
Original assignee: Fuji Xerox Co Ltd
Current assignee: Fujifilm Business Innovation Corp
Priority date: 2018-06-15
Filing date: 2018-10-30
Publication date: 2019-12-24
Also published as: JP2019218539A; JP7392299B2; EP3582012A1

Abstract

The invention relates to polytetrafluoroethylene particles, a composition, a layered material, an electrophotographic photoreceptor, a process cartridge, and an image forming apparatus. The polytetrafluoroethylene particles are dispersant-attached polytetrafluoroethylene particles, on the surfaces of which a dispersant having fluorine atoms is attached, and the content of perfluorooctanoic acid is 0ppb to 25ppb with respect to the polytetrafluoroethylene particles; the composition contains polytetrafluoroethylene particles and a dispersing agent having fluorine atoms, wherein the content of perfluorooctanoic acid is 0ppb to 25ppb with respect to the polytetrafluoroethylene particles.

Description

Polytetrafluoroethylene particle, composition, layered material, electrophotographic photoreceptor, process cartridge, and image forming apparatus

Technical Field

The invention relates to a polytetrafluoroethylene particle attached with a dispersant, a composition, a layered material, an electrophotographic photoreceptor, a process cartridge and an image forming apparatus.

Background

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

For example, in JP-A-2009-104145 (the term "JP-A" as used herein means an "unexamined Japanese patent application publication"), an electrophotographic photoreceptor containing fluorine atom-containing resin particles in its photosensitive layer is disclosed. Further, in JP-A-2009-104145, polytetrafluoroethylene particles are disclosed as fluorine atom-containing resin particles.

On the other hand, in JP- ｃA-2017-.

Disclosure of Invention

The polytetrafluoroethylene particles are used together with a dispersant having fluorine atoms (hereinafter also referred to as "fluorine-containing dispersant") by mixing with a component such as a dispersion medium or powder. However, when the state of the mixed components is changed (for example, the dispersion medium is evaporated or the powder is melted), the dispersibility of the polytetrafluoroethylene particles tends to be lowered.

Accordingly, the present invention provides a dispersant-attached polytetrafluoroethylene particle having high retention of a dispersed state even if the state of the mixed components changes, as compared with the case where the content of perfluorooctanoic acid (hereinafter also referred to as "PFOA") relative to polytetrafluoroethylene particles (hereinafter also referred to as "PTFE particles") exceeds 25 ppb.

<1>

According to an aspect of the present invention, there is provided a dispersing agent-attached polytetrafluoroethylene particle having a dispersing agent having fluorine atoms attached to the surface thereof, wherein the content of perfluorooctanoic acid is 0ppb to 25ppb with respect to the polytetrafluoroethylene particle.

<2>

The dispersant-attached polytetrafluoroethylene particles as stated in <1> having an average particle diameter of 0.2 μm to 4.5 μm.

<3>

The dispersant-attached polytetrafluoroethylene particle according to <1> or <2>, wherein the dispersant having a fluorine atom is a polymer obtained by homopolymerization or copolymerization of a polymerizable compound having a fluorinated alkyl group.

<4>

The dispersant-attached polytetrafluoroethylene particles as described in <3>, wherein the polymer obtained by homopolymerization or copolymerization of a polymerizable compound having a fluorinated alkyl group is a fluorinated alkyl group-containing polymer having a structural unit represented by the following Formula (FA), or a fluorinated alkyl group-containing polymer having a structural unit represented by the following Formula (FA) and a structural unit represented by the following Formula (FB):

wherein, in said Formulae (FA) and (FB), R^F1、R^F2、R^F3And R^F4Each independently represents a hydrogen atom or an alkyl group; x^F1Represents an alkylene chain, a halogen-substituted alkylene chain, -S-, -O-, -NH-or a single bond; y is^F1Represents an alkylene chain, a halogen-substituted alkylene chain, -C_fxH_2fx-1(OH)) -or a single bond; q^F1represents-O-or-NH-; fl, fm and fn each independently represent an integer of 1 or more; fp, fq, fr and fs each independently represents an integer of 0 or 1 or more; ft represents an integer of 1 to 7; fx represents an integer of 1 or more.

<5>

The dispersant-attached polytetrafluoroethylene particles according to any one of <1> to <4>, wherein the content of the dispersant having fluorine atoms is 0.5% by weight to 10% by weight with respect to the polytetrafluoroethylene particles.

<6>

The dispersant-attached polytetrafluoroethylene particles according to <5>, wherein the content of the dispersant having fluorine atoms is 1 to 7% by weight with respect to the polytetrafluoroethylene particles.

<7>

According to an aspect of the present invention, there is provided a composition comprising polytetrafluoroethylene particles and a dispersing agent having fluorine atoms, wherein the content of perfluorooctanoic acid is 0ppb to 25ppb with respect to the polytetrafluoroethylene particles.

<8>

The composition according to <7>, wherein the polytetrafluoroethylene particles have an average particle diameter of 0.2 μm to 4.5 μm.

<9>

The composition as described in <7> or <8>, which is in a liquid state or a solid state.

<10>

According to an aspect of the present invention, there is provided a layered material comprising polytetrafluoroethylene particles and a dispersing agent having fluorine atoms, wherein the content of perfluorooctanoic acid is 0ppb to 25ppb with respect to the polytetrafluoroethylene particles.

<11>

The layered material according to <10>, wherein the polytetrafluoroethylene particles have an average particle diameter of 0.2 μm to 4.5 μm.

<12>

An electrophotographic photoreceptor comprising a conductive substrate and a photosensitive layer provided on the conductive substrate, wherein an outermost surface layer is a layer containing the layered material of <10> or <11 >.

<13>

A process cartridge comprising the electrophotographic photoreceptor of <12>, wherein the process cartridge is detachably mountable to an image forming apparatus.

<14>

An image forming apparatus, comprising: <12> the electrophotographic photoreceptor, a charging unit that charges the surface of the electrophotographic photoreceptor, an electrostatic latent image forming unit that forms an electrostatic latent image on the surface of the charged electrophotographic photoreceptor, a developing unit that develops the electrostatic latent image formed on the surface of the electrophotographic photoreceptor with a developer containing a toner to form a toner image, and a transfer unit that transfers the toner image to the surface of a recording medium.

According to the invention of <1>, <2>, <3>, <4>, <5> or <6>, there is provided a dispersing agent-attached PTFE particles having high retention of a dispersed state even if the state of the mixed components is changed, as compared with the case where the content of PFOA relative to the PTFE particles exceeds 25 ppb.

According to the invention of <7>, <8> or <9>, there is provided a composition having high retentivity of the dispersed state of PTFE particles even if the state in which the components are mixed with the PTFE particles changes, as compared with the case where the content of PFOA relative to the PTFE particles exceeds 25 ppb.

According to the invention of <10>, <11>, <12>, <13> or <14>, there are provided a layered material having a high dispersion state of PTFE particles as compared with the case where the content of PFOA relative to PTFE particles exceeds 25ppb, an electrophotographic photoreceptor having an outermost surface made of the layered material, a process cartridge equipped with the electrophotographic photoreceptor, and an image forming apparatus equipped with the electrophotographic photoreceptor.

Drawings

Exemplary embodiments of the present invention will be described in detail based on the accompanying drawings, in which:

FIG. 1 is a schematic sectional view showing one example of a layer configuration of an electrophotographic photoreceptor of an exemplary embodiment;

FIG. 2 is a schematic configuration diagram showing one example of an image forming apparatus of an exemplary embodiment; and

fig. 3 is a schematic configuration diagram showing another example of the image forming apparatus of the exemplary embodiment.

[ description of reference numerals ]

1: undercoat layer, 2: charge generation layer, 3: charge transport layer, 4: conductive substrate, 7a, 7: electrophotographic photoreceptor, 8: charging device, 9: exposure apparatus, 11: developing device, 13: cleaning apparatus, 14: lubricant, 40: transfer apparatus, 50: intermediate transfer body, 100: image forming apparatus, 120: image forming apparatus, 131: cleaning blade, 132: fibrous member (roll-shaped), 133: fibrous member (flat brush shape), 300: processing box

Detailed Description

An exemplary embodiment as an example of the present invention will be described below.

(dispersant-attached polytetrafluoroethylene particles)

The dispersant-attached polytetrafluoroethylene particles (dispersant-attached PTFE particles) of the present exemplary embodiment are PTFE particles having a dispersant (fluorine-containing dispersant) having a fluorine atom attached to the surface thereof.

In addition, in the dispersant-attached PTFE particles of the present exemplary embodiment, the content of perfluorooctanoic acid (PFOA) relative to polytetrafluoroethylene particles (PTFE particles) is 0ppb to 25 ppb.

With the above configuration, the dispersion agent of the present exemplary embodiment adheres to the PTFE particles with high retention of the dispersed state even if the state of the mixed components changes. The reason for this is presumed as follows.

The PTFE particles are generally used with the fluorine-containing dispersant by mixing with a component such as a dispersion medium or powder. However, when the state of the mixed components is changed (for example, the dispersion medium is evaporated or the powder is melted), the dispersibility of the polytetrafluoroethylene particles tends to be lowered.

Specifically, for example, in the case where a liquid composition (for example, a coating solution for forming a layer) containing a resin and a dispersion medium is used together with PTFE particles and a fluorine-containing dispersant to form a layered material containing PTFE particles, drying of the dispersion medium is performed in the process of forming the layered material. Then, in the course of drying (i.e., evaporating) the dispersion medium, the dispersibility of the PTFE particles is reduced, sometimes causing aggregation of the PTFE particles.

Further, for example, in the case where a solid composition (e.g., powder coating) containing resin particles is used together with PTFE particles and a fluorine-containing dispersant to form a layered material containing PTFE particles, melting of the resin occurs in the process of forming the layered material. Then, in the process of melting the resin, the dispersibility of the PTFE particles is reduced, sometimes causing the aggregation of the PTFE particles.

As a result, a layered material having PTFE particles in a low dispersion state is formed. The reason for this is presumed as follows.

Since PFOA is used or produced as a by-product in the production process of PTFE particles, PTFE particles usually contain PFOA.

In the case where PFOA is present, although the PTFE particles are kept in a highly dispersed state by the fluorine-containing dispersant in the composition state, when the state of the mixed components is changed, the adhesion state of the fluorine-containing dispersant to the PTFE particles is changed. Specifically, it is considered that a part of the fluorine-containing dispersant is separated from the PTFE particles due to PFOA. Therefore, the dispersibility of the PTFE particles is reduced, causing the PTFE particles to aggregate.

Therefore, in the dispersant-attached PTFE particles of the present exemplary embodiment, the PFOA content is 0ppb to 25ppb with respect to the PTFE particles. In other words, the PTFE particles do not contain PFOA, or even if the PTFE particles contain PFOA, the PFOA content is suppressed. Therefore, the change in the state of adhesion of the fluorine-containing dispersant to the PTFE particles caused by PFOA or generated upon a change in the state of the mixed components is suppressed.

From the above, it is presumed that the PTFE particles adhered to the dispersant of the present exemplary embodiment have high retentivity of the dispersed state even if the state of the mixed component changes.

Hereinafter, the dispersant-attached PTFE particles of the present exemplary embodiment will be described in detail.

The PFOA content is 0ppb to 25ppb with respect to the PTFE particles, and from the viewpoint of improving the retention of the dispersed state, 0ppb to 20ppb is preferable, and 0ppb to 15ppb is more preferable. "ppb" is on a weight basis.

Methods for reducing the PFOA content include methods in which PTFE particles are thoroughly washed with pure water, alkaline water, alcohols (e.g., methanol, ethanol, or isopropanol), ketones (e.g., acetone, methyl ethyl ketone, or methyl isobutyl ketone), esters (e.g., ethyl acetate), or other common organic solvents (e.g., toluene or tetrahydrofuran). Although washing may be performed at room temperature, PFOA content may be efficiently reduced by performing washing under heating.

The PFOA content is a value measured by the method shown below.

Pretreatment of the sample

In the case of a layered material containing dispersion-attached PTFE particles, the layered material is immersed in a solvent (e.g., tetrahydrofuran) to dissolve the PTFE particles and substances other than those insoluble in the solvent, and then the solution is dropped into pure water to separate the deposit by filtration. The PFOA-containing solution thus obtained is collected. Further, the insoluble matter obtained by filtration was dissolved in a solvent, and then the solution was added dropwise to pure water, and the precipitate was separated by filtration. The operation of collecting the PFOA-containing solution thus obtained is repeated five times, and the aqueous solution collected through the entire operation is referred to as a pretreated aqueous solution.

In the case of a composition containing dispersion-adhering PTFE particles, the composition is subjected to the same procedure as in the case of the layered material to obtain a pretreated aqueous solution.

In the case of the dispersion agent-attached PTFE particles, the same procedure as in the case of the layered material is performed on the dispersion agent-attached PTFE particles to obtain a pretreated aqueous solution.

Measurement-

With respect to the pretreated aqueous solution obtained by the above-mentioned means, preparation and measurement of a sample solution were carried out according to the method shown in "perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) analysis in environmental water, sediments and organisms of institute of environmental sciences and public health in shicheng county.

The average particle diameter of the PTFE particles (average particle diameter of the PTFE particles to which the dispersant is attached) is not particularly limited, and is preferably 0.2 μm to 4.5 μm, more preferably 0.2 μm to 4 μm. PTFE particles having an average particle diameter of 0.2 μm to 4.5 μm tend to contain a large amount of PFOA. Therefore, PTFE particles having an average particle diameter of 0.2 μm to 4.5 μm are particularly liable to deteriorate in a dispersed state when the state of the mixed components is changed. However, by controlling the PFOA content within the above range, even for PTFE particles having an average particle diameter of 0.2 μm to 4.5 μm, the retention of the dispersed state is improved when the state of the mixed components is changed.

The average particle diameter of the PTFE particles is a value measured by the method shown below.

The maximum diameter of the fluororesin particles (secondary particles formed by aggregation of primary particles) is measured by observation (for example, at a magnification of 5,000 times or more) with a Scanning Electron Microscope (SEM). The measurement was performed with 50 particles, and the average value was regarded as the average particle diameter of the PTFE particles. As an SEM, JSM-6700F manufactured by JEOL was used, and a secondary electron image with an acceleration voltage of 5kV was observed.

The fluorine-containing dispersant includes a polymer obtained by homopolymerization or copolymerization of a polymerizable compound having a fluorinated alkyl group (hereinafter also referred to as "fluorinated alkyl group-containing polymer").

The fluorine-containing dispersant specifically includes, for example, a homopolymer of a (meth) acrylate having a fluorinated alkyl group and a random or block copolymer between the (meth) acrylate having a fluorinated alkyl group and a monomer having no fluorine atom. By (meth) acrylate is meant both acrylate and methacrylate.

The (meth) acrylate having a fluorinated alkyl group includes, for example, 2,2, 2-trifluoroethyl (meth) acrylate and 2,2,3,3, 3-pentafluoropropyl (meth) acrylate.

Monomers having no fluorine atom include, for example, (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, isooctyl (meth) acrylate, dodecyl (meth) acrylate, stearyl (meth) acrylate, isobornyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-methoxyethyl (meth) acrylate, methoxytriethylene glycol (meth) acrylate, 2-ethoxyethyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, benzyl (meth) acrylate, ethylcarbitol (meth) acrylate, phenoxyethyl (meth) acrylate, 2-hydroxy ester (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, t-butyl (meth) acrylate, n-butyl (meth) acrylate, Phenoxy polyethylene glycol (meth) acrylate, hydroxyethyl o-phenyl phenol (meth) acrylate, and o-phenyl phenol glycidyl ether (meth) acrylate.

Further, the fluorine-containing dispersant specifically includes, for example, block or branched polymers disclosed in U.S. Pat. No.5,637,142 and Japanese patent No.4,251,662. Further, the fluorine-containing dispersant specifically includes a fluorine-based surfactant.

Among these, the fluorinated dispersant is preferably a fluorinated alkyl group-containing polymer having a structural unit represented by the following Formula (FA), and more preferably a fluorinated alkyl group-containing polymer having a structural unit represented by the following Formula (FA) and a structural unit represented by the following Formula (FB).

The fluorinated alkyl group-containing polymer having a structural unit represented by the following Formula (FA) and a structural unit represented by the following Formula (FB) is described below.

In the Formulae (FA) and (FB), R^F1、R^F2、R^F3And R^F4Each independently represents a hydrogen atom or an alkyl group.

X^F1Represents an alkylene chain, a halogen-substituted alkylene chain, -S-, -O-, -NH-, or a single bond.

Y^F1Represents an alkylene chain, a halogen-substituted alkylene chain, -C_fxH_2fx-1(OH)) -, or a single bond.

Q^F1represents-O-or-NH-.

fl, fm and fn each independently represent an integer of 1 or more.

fp, fq, fr and fs each independently represents an integer of 0 or 1 or more.

ft represents an integer of 1 to 7.

fx represents an integer of 1 or more.

R in the Formulae (FA) and (FB)^F1、R^F2、R^F3And R^F4The group represented by each is preferably a hydrogen atom, a methyl group, an ethyl group or a propyl group, more preferably a hydrogen atom or a methyl group, and still more preferably a methyl group.

X in Formulae (FA) and (FB)^F1And Y^F1The alkylene chain (unsubstituted alkylene chain or halogen-substituted alkylene chain) represented by each is preferably a straight or branched alkyl chain having 1 to 10 carbon atoms.

Y^F1Is represented by-C_fxH_2fx-1Fx in (OH)) -is preferably an integer of 1 to 10.

fp, fq, fr and fs each independently preferably represents 0 or an integer of 1 to 10.

fn is preferably 1 to 60, for example.

Here, in the fluorine-containing dispersant, the ratio of the structural unit represented by the Formula (FA) to the structural unit represented by the Formula (FB), i.e., fl: fm, is preferably 1:9 to 9:1, more preferably 3:7 to 7: 3.

Further, the fluorine-containing dispersant may contain a structural unit represented by the Formula (FC) in addition to the structural unit represented by the Formula (FA) and the structural unit represented by the Formula (FB). The content ratio of the structural unit represented by the Formula (FC) to the total of the structural unit represented by the Formula (FA) and the structural unit represented by the Formula (FB), i.e., fl + fm, is preferably 10:0 to 7:3, more preferably 9:1 to 7:3, in terms of (fl + fm: fz) ratio.

(FC)

In Formula (FC), R^F5And R^F6Each independently represents a hydrogen atom or an alkyl group.

fz represents an integer of 1 or more.

R in the Formula (FC)^F5And R^F6The group represented by each is preferably a hydrogen atom, a methyl group, an ethyl group or a propyl group, more preferably a hydrogen atom or a methyl group, and still more preferably a methyl group.

Commercially available products of the fluorine-containing dispersant include, for example, GF300 and GF400 (manufactured by Toagosei co., Ltd.), Surflon series (AGC Seimi Chemical co., Ltd.), Futargent series (manufactured by NEOS co., Ltd.), PF series (manufactured by Kitamura Chemicals co., Ltd.), Megafac series (manufactured by DIC corp.), and FC series (manufactured by 3M co., Ltd.).

The weight average molecular weight of the fluorine-containing dispersant is, for example, preferably 2,000 to 250,000, more preferably 3,000 to 150,000, and still more preferably 50,000 to 100,000.

The weight average molecular weight of the fluorine-containing dispersant is a value measured by Gel Permeation Chromatography (GPC). For example, molecular weight measurement was performed by GPC using HLC-8120GPC (manufactured by Tosoh Corp.) as a measurement device, TSKgel GMHHR-M + TSKgel GMHHR-M (7.8mm I.D.30cm) (manufactured by Tosoh Corp.) as a column, and chloroform as a solvent. The weight average molecular weight (Mw) was calculated from the measurement results by a molecular weight calibration curve prepared using monodisperse polystyrene standard samples.

The content of the fluorine-containing dispersant is, for example, preferably 0.5 to 10% by weight, more preferably 1 to 7% by weight, relative to the PTFE particles.

The fluorine-containing dispersant may be used singly or in combination of two or more.

The method for producing the dispersant-attached PTFE particles of the present exemplary embodiment includes, for example:

(1) a method of blending PTFE particles and a fluorine-containing dispersant in a dispersion medium to prepare a dispersion of the PTFE particles, and then removing the dispersion medium from the dispersion;

(2) a method of mixing PTFE particles and a fluorine-containing dispersant using a dry powder mixer to attach the fluorine-containing dispersant to the PTFE particles;

(3) a method in which a fluorine-containing dispersant dissolved in a solvent is added dropwise to PTFE particles with stirring, and then the solvent is removed.

(composition)

The composition of the present exemplary embodiment contains PTFE particles and a fluorine-containing dispersant. In addition, in the composition of the present exemplary embodiment, the PEOA content is 0ppb to 25ppb with respect to the PTFE particles.

In other words, the composition of the present exemplary embodiment contains PTFE particles to which the dispersant of the present exemplary embodiment is attached. Therefore, the composition of the present exemplary embodiment is a composition having high retention of the dispersed state of the PTFE particles even when the state of the component mixed with the PTFE particles changes.

However, the composition of the present exemplary embodiment may be a composition prepared by mixing the PTFE particles to which the previously prepared dispersant is attached with other components (e.g., the dispersion medium or the resin particles other than the PTFE particles), or a composition in which the PTFE particles, the fluorine-containing dispersant, and other components (e.g., the dispersion medium or the resin particles other than the PTFE particles) are mixed.

The composition of the present exemplary embodiment may be any one of a liquid composition and a solid composition.

The liquid composition includes, for example, a PTFE particle dispersion containing PTFE particles, a fluorine-containing dispersant, and a dispersion medium, and a coating liquid for forming a layered material in which a resin is mixed into the PTFE particle dispersion.

Solid state compositions include, for example, compositions containing dispersant-attached PTFE particles, resin particles (e.g., toner particles or powder coating particles).

(layered Material)

The layered material of the present exemplary embodiment contains PTFE particles and a fluorine-containing dispersant. In addition, in the layered material of the present exemplary embodiment, the PEOA content is 0ppb to 25ppb with respect to the PTFE particles.

In other words, the layered material of the present exemplary embodiment contains the dispersant-attached PTFE particles. Specifically, the layered material of the present exemplary embodiment is a layer formed from the composition of the present exemplary embodiment.

Therefore, the layered material of the present exemplary embodiment is a layered material having high retentivity of the dispersed state of the PTFE particles. Further, the layered material of the present exemplary embodiment is a layered material excellent in surface characteristics such as lubricity or hydrophobicity (water repellency) (particularly a layered material having a small amount of irregularities in surface characteristics).

The layered material of the present exemplary embodiment includes, for example, the outermost surface layer of the electrophotographic photoreceptor, a toner image, a powder coating layer, and a sliding layer.

In the layered material of the present exemplary embodiment, the content of the PTFE particles is preferably 0.1 to 40 wt%, more preferably 1 to 30 wt%, from the viewpoint of exerting the above-described surface characteristics.

(electrophotographic photoreceptor)

The electrophotographic photoreceptor (hereinafter also referred to as "photoreceptor") of the present exemplary embodiment has a conductive substrate and a photosensitive layer provided on the conductive substrate, in which the outermost surface layer is a layer formed of the layered material of the present exemplary embodiment.

The outermost surface layer formed of the layered material is a charge transport layer of a laminated photosensitive layer, a single-layer photosensitive layer, a surface protective layer, or the like.

Since the photoreceptor of the present exemplary embodiment has a layer formed of the layered material of the present exemplary embodiment as the outermost surface layer, it has high wear resistance. Specifically, when the dispersibility of the PTFE particles contained in the outermost surface layer is low, the photoreceptor tends to generate image defects (specifically, striped image unevenness). However, in the photoreceptor of the present exemplary embodiment, since the PTFE particles are contained in the outermost surface layer in a highly dispersed state, the above-described image defects are suppressed.

The electrophotographic photoreceptor of the present exemplary embodiment will be described below with reference to the drawings.

The electrophotographic photoreceptor 7 shown in fig. 1 includes, for example, a photoreceptor 7 having a configuration 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 substrate 4. The charge generation layer 2 and the charge transport layer 3 constitute a photosensitive layer 5.

Further, the electrophotographic photoreceptor 7 may have a layer configuration in which the undercoat layer 1 is omitted.

Further, the electrophotographic photoreceptor 7 may be a photoreceptor having a single-layer type photosensitive layer which integrates the functions of the charge generation layer 2 and the charge transport layer 3. In the case of a photoreceptor having a monolayer type photosensitive layer, the monolayer type photosensitive layer constitutes the outermost surface layer.

Further, the electrophotographic photoreceptor 7 may be a photoreceptor having a surface protective layer on the charge transport layer 3 or the monolayer type photosensitive layer. In the case of a photoreceptor having a surface protective layer, the surface protective layer constitutes the outermost surface layer.

Hereinafter, each layer of the electrophotographic photoreceptor of the present exemplary embodiment will be described in detail. In the description, reference numerals will be omitted.

(conductive substrate)

The conductive substrate includes, for example, a metal plate, a metal drum, and a metal tape containing a metal (aluminum, copper, zinc, chromium, nickel, molybdenum, vanadium, indium, gold, platinum, or the like) or an alloy (stainless steel or the like). Further, the conductive substrate includes, for example, paper, resin film, and tape on which a conductive compound (e.g., a conductive polymer or indium oxide), a metal (e.g., aluminum, palladium, or gold), or an alloy is coated, deposited, or laminated. Here, "electrically conductive" means having a volume resistivity of less than 10¹³Ωcm。

In the case where the electrophotographic photoreceptor is used in a laser printer, in order to prevent interference fringes from being generated upon irradiation with laser light, it is preferable that the surface of the conductive base material is roughened so that the center line average roughness Ra is 0.04 μm to 0.5 μm. Further, in the case where non-interference light is used for the light source, roughening of the surface for preventing interference fringes is not particularly necessary, but roughening of the surface is suitable for prolonging the life because generation of defects due to unevenness of the surface of the conductive base material is prevented.

The roughening method includes, for example, wet honing in which a polishing agent is suspended in water and the suspension is blown to a conductive substrate, centerless grinding in which the conductive substrate is pressure-contacted to a rotary grindstone and an abrasive process is continuously performed, and anodic oxidation treatment.

The roughening method also includes a method of dispersing a conductive or semiconductive powder in a resin, forming a layer on the surface of a conductive substrate, and performing roughening using particles dispersed in the layer without performing surface roughening of the conductive substrate.

The roughening treatment using anodization is a treatment of forming an oxide film on the surface of a conductive substrate using a metal (for example, aluminum) to be anodized in an electrolyte solution as an anode. The electrolyte solution includes, for example, a sulfuric acid solution and an oxalic acid solution. However, the porous anodic oxide film formed by anodic oxidation itself is chemically active and easily contaminated, and its resistance fluctuation is large due to the environment. Therefore, it is preferable to perform the following sealing treatment with respect to the porous anodic oxide film: the micropores of the oxide film are sealed by volume expansion by hydration reaction in pressurized steam or boiling water (metal salt such as nickel may be added), and the oxide film is changed into a more stable hydrated oxide.

The film thickness of the anodic oxide film is preferably 0.3 μm to 15 μm, for example. When the film thickness is within the above range, the injection blocking property is easily exhibited and the increase in residual potential due to repeated use is prevented.

The conductive substrate may be subjected to treatment with an acidic treatment liquid or boehmite treatment.

The treatment with the acidic treatment liquid was performed as follows. First, an acidic treatment liquid containing phosphoric acid, chromic acid, and hydrofluoric acid is prepared. The mixing ratio of phosphoric acid, chromic acid and hydrofluoric acid in the acidic treatment liquid is 10 to 11% by weight of phosphoric acid, 3 to 5% by weight of chromic acid and 0.5 to 2% by weight of hydrofluoric acid. Further, the concentration of the total acid is suitably in the range of 13.5 to 18% by weight. The treatment temperature is preferably 42 ℃ to 48 ℃. The film thickness of the coating film is preferably 0.3 μm to 15 μm.

The boehmite treatment is performed by immersing the conductive substrate in pure water at a temperature of 90 ℃ to 100 ℃ for 5 minutes to 60 minutes or by contacting the conductive substrate with heating steam at a temperature of 90 ℃ to 120 ℃ for 5 minutes to 60 minutes. The film thickness of the coating film is preferably 0.1 μm to 5 μm. The membrane may be further anodized using an electrolyte solution having low coating film solubility, such as adipic acid, boric acid, borate, phosphate, phthalate, maleate, benzoate, tartrate, or citrate.

(undercoat layer)

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

Inorganic particles include, for example, a powder having a resistance (volume resistivity) of 10²Omega cm to 10¹¹Omega cm of inorganic particles.

Among these, as the inorganic particles having the above resistance value, metal oxide particles such as tin oxide particles, titanium oxide particles, zinc oxide particles or zirconium oxide particles are preferable, and zinc oxide particles are particularly preferable.

The specific surface area of the inorganic particles using the BET method is, for example, suitably 10m²More than g.

The volume average particle diameter of the inorganic particles is, for example, suitably 50nm to 2,000nm (preferably 60nm to 1,000 nm).

The content of the inorganic particles is, for example, preferably 10 to 80% by weight, more preferably 40 to 80% by weight, relative to the binder resin.

The inorganic particles may be surface treated. The inorganic particles may use two or more kinds of differently surface-treated particles or particles having different particle diameters from each other in combination.

The surface treatment agent includes, for example, a silane coupling agent, a titanate coupling agent, an aluminum coupling agent, and a surfactant. In particular, a silane coupling agent is preferable, and a silane coupling agent having an amino group is more preferable.

The silane coupling agent having an amino group includes, for example, 3-aminopropyltriethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane and N, N-bis (2-hydroxyethyl) -3-aminopropyltriethoxysilane, but the silane coupling agent having an amino group is not limited thereto.

The silane coupling agent may be used in combination of two or more. For example, a silane coupling agent having an amino group and another silane coupling agent may be combined with each other. Another silane coupling agent includes, for example, vinyltrimethoxysilane, 3-methacryloxypropyl-tris (2-methoxyethoxy) silane, 2- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, 3-mercaptopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, N, n-bis (2-hydroxyethyl) -3-aminopropyltriethoxysilane and 3-chloropropyltrimethoxysilane, but the other silane coupling agent is not limited thereto.

As the surface treatment method using the surface treatment agent, any method may be used as long as the method is a known method, and any one of a dry method and a wet method may be used.

The treatment amount of the surface treatment agent is preferably 0.5 to 10% by weight with respect to the inorganic particles.

The undercoat layer preferably contains an electron-accepting compound (acceptor compound) and inorganic particles from the viewpoint of improvement in long-term stability of electrical characteristics and carrier blocking property.

Electron accepting compounds include, for example, electron transporting substances such as: quinone compounds such as chloranil or tetrabromo-p-benzoquinone; tetracyanoquinodimethane compounds; fluorenone compounds, such as 2,4, 7-trinitrofluorenone or 2,4,5, 7-tetranitro-9-fluorenone; oxadiazole compounds such as 2- (4-biphenyl) -5- (4-tert-butylphenyl) -1,3, 4-oxadiazole, 2, 5-bis (4-naphthyl) -1,3, 4-oxadiazole or 2, 5-bis (4-diethylaminophenyl) -1,3, 4-oxadiazole; a xanthone compound; a thiophene compound; diphenoquinone compounds, such as 3,3 ', 5, 5' -tetra-tert-butyl diphenoquinone.

Specifically, a compound having an anthraquinone structure is preferable as the electron accepting compound. As the compound having an anthraquinone structure, for example, a hydroxyanthraquinone compound, an aminoanthraquinone compound or an aminohydroxyanthraquinone compound is preferable, and anthraquinone, alizarin, quinizarine, purpurine or viologen is particularly preferable.

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

Methods for attaching the electron accepting compound to the surface of the inorganic particle include, for example, a dry method and a wet method.

The dry method is as follows: the electron accepting compound is directly dropped or the electron accepting compound dissolved in the organic solvent is dropped while the inorganic particles are stirred with a mixer or the like having a large shearing force, the electron accepting compound is sprayed with dry air or nitrogen gas, and the electron accepting compound is attached to the surface of the inorganic particles. The dropping or spraying of the electron accepting compound is suitably carried out at a temperature lower than or equal to the boiling point of the solvent. The electron accepting compound may be further baked at a temperature of 100 ℃ or higher after dropping or spraying. The baking is not particularly limited as long as the baking is performed under the same temperature and time conditions as those under which the above-described electrophotographic characteristics can be obtained.

The wet method is as follows: dispersing inorganic particles in a solvent using stirring, ultrasonic waves, a sand mill, an attritor, or a ball mill, adding an electron accepting compound thereto, stirring the mixture or dispersing the compound in the mixture, and removing the solvent to attach the electron accepting compound to the surface of the inorganic particles. In the solvent removal method, the solvent may be removed by, for example, filtration or distillation. After removing the solvent, the resultant may be further baked at a temperature of 100 ℃ or higher. The baking is not particularly limited as long as the baking is performed under the same temperature and time conditions as those under which the above-described electrophotographic characteristics can be obtained. In the wet method, moisture contained in the inorganic particles may be removed before the electron accepting compound is added, and examples thereof include a method of removing moisture while stirring and heating in a solvent and a method of removing moisture while azeotroping with a solvent.

The attachment of the electron accepting compound may be performed before or after the surface treatment of the inorganic particles with the surface treatment agent, or the attachment of the electron accepting compound and the surface treatment with the surface treatment agent may be performed simultaneously.

The content of the electron accepting compound is, for example, suitably 0.01 to 20% by weight, preferably 0.01 to 10% by weight, relative to the inorganic particles.

The binder resin for the undercoat layer includes, for example, known polymer compounds such as acetal resin (e.g., polyvinyl butyral), polyvinyl alcohol resin, polyvinyl acetal resin, casein resin, polyamide resin, cellulose resin, gelatin, polyurethane resin, polyester resin, unsaturated polyester resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinyl acetate resin, vinyl chloride-vinyl acetate-maleic anhydride resin, silicone resin, siloxane-alkyd resin, urea resin, phenol resin, melamine resin, urethane resin, alkyd resin, or epoxy resin, and known materials such as zirconium chelate compound, titanium chelate compound, aluminum chelate compound, titanium alkoxide compound, organotitanium compound, or silane coupling agent.

The binder resin for the undercoat layer includes, for example, a charge transporting resin having a charge transporting group and a conductive resin (e.g., polyaniline).

Among them, as the binder resin for the undercoat layer, a resin insoluble in the coating solvent of the upper layer is preferable, and particularly preferable are: thermosetting resins such as urea resins, phenol resins, melamine resins, urethane resins, unsaturated polyester resins, alkyd resins, or epoxy resins; and a resin obtained by a reaction between a curing agent and at least one resin selected from the group consisting of a polyamide resin, a polyester resin, a polyether resin, a methacrylic resin, an acrylic resin, a polyvinyl alcohol resin, and a polyvinyl acetal resin.

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 to improve electrical characteristics, environmental stability, and image quality.

The additive includes a known material, for example, a polycyclic fused or azo electron transporting pigment, a zirconium chelate compound, a titanium chelate compound, an aluminum chelate compound, a titanium alkoxide compound, an organotitanium compound, or a silane coupling agent. The silane coupling agent is used for the surface treatment of the inorganic particles as described above, but may be added as an additive to the undercoat layer.

Silane coupling agents as additives include, for example, vinyltrimethoxysilane, 3-methacryloxypropyl-tris (2-methoxyethoxy) silane, 2- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, 3-mercaptopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, N-bis (2-hydroxyethyl) -3-aminopropyltriethoxysilane and 3-chloropropyltrimethoxysilane.

Zirconium chelate compounds include, for example, zirconium butoxide, zirconium ethylacetoacetate, zirconium triethanolamine, zirconium acetylacetonate butoxide, zirconium ethylacetoacetate, zirconium acetate, zirconium oxalate, zirconium lactate, zirconium phosphonate, zirconium octoate, zirconium naphthenate, zirconium laurate, zirconium stearate, zirconium isostearate, zirconium methacrylate butoxide, zirconium stearate butoxide, and zirconium isostearate.

Titanium chelate compounds include, for example, tetraisopropyl titanate, tetra-n-butyl titanate, butyl titanate dimer, tetra- (2-ethylhexyl) titanate, titanium acetylacetonate, titanium polyacetylacetonate, titanium octenoglycolate, titanium ammonium lactate, titanium ethyl lactate, titanium triethanolamine and titanium polyhydroxystearate.

Aluminum chelating compounds include, for example, aluminum isopropoxide, aluminum diisopropoxide monobutyloxide, aluminum butyrate, aluminum diisopropoxide diethyl acetoacetate, and aluminum tris (acetoacetate).

These additives may be used alone, in combination of a plurality of compounds or as a polycondensate.

The vickers hardness of the undercoat layer is suitably 35 or more.

The surface roughness (ten-point average roughness) of the undercoat layer is appropriately adjusted to 1/(4n) (n is the refractive index of the upper layer) to (1/2) of the laser wavelength λ of the exposure used to prevent moire images.

Resins and the like may be added to the undercoat layer to adjust the surface roughness. The resin particles include, for example, silicone resin particles and crosslinked polymethylmethacrylate particles. Further, the surface of the undercoat layer may be polished to adjust the surface roughness. The polishing methods include, for example, soft polishing (buff polishing), sand blasting, wet honing, and lapping.

The formation of the undercoat layer is not particularly limited, and a known formation method is used. For example, the undercoat layer is formed as follows: a coating film is formed using a coating solution for formation of an undercoat layer obtained by adding the above components to a solvent, the coating film is dried, and the dried film is heated as necessary.

The solvent used for preparing the coating solution for undercoat layer formation includes known organic solvents such as alcohol solvents, aromatic hydrocarbon solvents, halogenated hydrocarbon solvents, ketone alcohol solvents, ether solvents, and ester solvents.

The solvent specifically includes common organic solvents such as methanol, ethanol, n-propanol, isopropanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, ethyl acetate, n-butyl acetate, dioxane, tetrahydrofuran, dichloromethane, chloroform, chlorobenzene, and toluene.

Methods for dispersing the inorganic particles while preparing the coating solution for forming the undercoat layer include known methods such as roll mills, ball mills, vibratory ball mills, attritors, sand mills, colloid mills, and paint stirrers.

The method of applying the coating solution for forming the undercoat layer on the conductive substrate includes general methods such as 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, or a curtain coating method.

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

(intermediate 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. The resin used for the intermediate layer is a polymer compound such as an acetal resin (e.g., polyvinyl butyral), a polyvinyl alcohol resin, a polyvinyl acetal resin, a casein resin, a polyamide resin, a cellulose resin, gelatin, a polyurethane resin, a polyester resin, a methacrylic resin, an acrylic resin, a polyvinyl chloride resin, a polyvinyl acetate resin, a vinyl chloride-vinyl acetate-maleic anhydride resin, a silicone-alkyd resin, a phenol resin, and a melamine resin.

The intermediate layer may be a layer containing an organometallic compound. The organometallic compound used for the intermediate layer includes, for example, an organometallic compound containing a metal atom such as zirconium, titanium, aluminum, manganese, or silicon.

The compounds used in the intermediate layer may be used alone, in combination of a plurality of compounds, or as a polycondensate.

Among them, 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 known formation method is used. For example, the intermediate layer is formed as follows: a coating film is formed using a coating solution for intermediate layer formation obtained by adding the above components to a solvent, the coating film is dried, and the dried film is heated as necessary.

The coating method for forming the intermediate layer includes general methods such as a dip coating method, an extrusion coating method, a wire bar coating method, a spray coating method, a blade coating method, a knife coating method, or a curtain coating method.

The film thickness of the intermediate layer is preferably set to 0.1 μm to 3 μm, for example. In addition, the intermediate layer may serve as a primer layer.

(Charge generation layer)

The charge generation layer is, for example, a layer containing a charge generation material and a binder resin. The charge generation layer may be a vapor deposition layer of a charge generation material. In the case of using an incoherent light source such as a Light Emitting Diode (LED) or an organic Electroluminescence (EL) image array, a vapor-deposited layer of a charge generation material is preferable.

The charge generation material includes: for example, azo pigments such as disazo or trisazo; fused ring aromatic pigments such as dibromoanthanthrone; perylene pigments; a pyrrolopyrrole pigment; phthalocyanine pigments; zinc oxide; and trigonal selenium.

Among them, in order to respond to laser exposure in the near infrared region, a metal phthalocyanine pigment or a metal-free phthalocyanine pigment is preferably used as the charge generating material. Specifically, for example, hydroxygallium phthalocyanine such as disclosed in JP-A-5-263007 and JP-A-5-279591; chlorogallium phthalocyanine such as disclosed in JP-A-5-98181; dichlorotin phthalocyanines such as those disclosed in JP-A-5-140472 and JP-A-5-140473; and titanyl phthalocyanines such as disclosed in JP-A-4-189873.

On the other hand, in response to laser exposure in the near ultraviolet region, as the charge generating material, preferred are: for example, dibromoanthanthrone; a thioindigo pigment; a porphyrazine compound; zinc oxide; trigonal selenium; and disazo pigments disclosed in JP-A-2004-78147 and JP-A-2005-181992.

The above-described charge generation material can be used even in the case of using an array such as an LED or an organic EL image having an emission center wavelength of 450nm to 780 nm. However, in the case of using a photosensitive layer as a thin film having a thickness of 20 μm or less from the viewpoint of resolution, the field strength in the photosensitive layer increases, and a decrease in charging due to injection of charges from the substrate and an image defect called a black spot easily occur. This phenomenon remarkably occurs when a charge generation material which is a p-type semiconductor such as trigonal selenium or phthalocyanine pigment and easily generates dark current is used.

In contrast, in the case of using an n-type semiconductor, for example, using a condensed ring aromatic pigment, a perylene pigment, or an azo pigment as a charge generating material, a dark current is hardly generated, and an image defect called a black spot can be prevented even in the case of using a thin film. As the n-type charge generation material, for example, the compounds (CG-1) to (CG-27) disclosed in paragraphs [0288] to [0291] of JP-A-2012-155282 are used, but the n-type charge generation material is not limited thereto.

Using a common time-of-flight method, n-type is determined by the polarity of a flowing photocurrent, and a material that easily flows electrons, not holes, as carriers is determined as n-type.

The binder resin for the charge generation layer is selected from a wide range of insulating resins, and the binder resin may be selected from organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene, polyvinylpyrene and polysilane.

The binder resin includes, for example, polyvinyl butyral resin, polyarylate resin (for example, a polycondensate of bisphenol and aromatic divalent carboxylic acid), polycarbonate resin, polyester resin, phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyamide resin, acrylic resin, polyacrylamide resin, polyvinyl pyridine resin, cellulose resin, urethane resin, epoxy resin, casein, polyvinyl alcohol resin, and polyvinyl pyrrolidone resin. In this context"insulation" means a volume resistivity of 10¹³Omega cm or more.

These binder resins are used singly or in combination of two or more.

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

The charge generation layer may contain other known additives.

The formation of the charge generation layer is not particularly limited, and a known formation method is used. For example, the charge generation layer is formed as follows: a coating film is formed using a charge generation layer-forming coating solution obtained by adding the above components to a solvent, the coating film is dried, and the dried film is heated as necessary. The formation of the charge generation layer may be performed by vapor deposition of a charge generation material. Formation of the charge generation layer by vapor deposition is particularly preferable in the case of using a condensed ring aromatic pigment or a perylene pigment as the charge generation material.

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

As a method of dispersing particles (for example, a charge generating material) in the coating solution for charge generation layer formation, a medium dispersing apparatus such as a ball mill, a vibration ball mill, an attritor, a sand mill, or a horizontal sand mill, or a medium-free dispersing apparatus such as a stirrer, an ultrasonic dispersing apparatus, a roll mill, or a high-pressure homogenizer is used. The high-pressure homogenizer includes, for example, a collision type in which a dispersion liquid is dispersed by causing liquid-liquid collision or liquid-wall collision in a high-pressure state, and a penetration method in which a dispersion liquid is dispersed by penetrating a dispersion liquid through a minute flow path in a high-pressure state.

When the dispersion is performed, the average particle diameter of the charge generating material in the coating solution for forming a charge generation layer is effectively 0.5 μm or less, preferably 0.3 μm or less, and more preferably 0.15 μm or less.

Methods for coating the charge generation layer forming coating solution on the undercoat layer (or on the intermediate layer) include common methods such as 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, or a curtain coating method.

For example, the film thickness of the charge generation layer is preferably set to 0.1 μm to 5.0 μm, more preferably 0.2 μm to 2.0 μm.

(Charge transport layer)

The charge transport layer is a layer containing a charge transport material and a binder resin. The charge transport layer may be a layer containing a polymeric charge transport material.

The charge transport material includes an electron transport compound, for example, a quinone compound such as p-benzoquinone, chloranil, tetrabromo-p-benzoquinone, or anthraquinone; tetracyanoquinodimethane compounds; fluorenone compounds, such as 2,4, 7-trinitrofluorenone; a xanthone compound; a benzophenone compound; a cyanovinyl compound; and an olefinic compound. The charge transport material also includes a hole transport compound such as a triarylamine compound, a biphenylamine compound, an arylalkane compound, an aryl-substituted ethylene compound, a stilbene compound, an anthracene compound, or a hydrazone compound. These charge transporting materials may be used alone or in combination of two or more, but the charge transporting material is not limited thereto.

The charge transport material is preferably a triarylamine derivative represented by the following structural formula (a-1) or a benzidine derivative represented by the following structural formula (a-2) from the viewpoint of charge mobility.

In the structural formula (a-1), Ar^T1、Ar^T2And Ar^T3Each independently represents a substituted or unsubstituted aryl group, -C₆H₄-C(R^T4)＝C(R^T5)(R^T6) or-C₆H₄-CH＝CH-CH＝C(R^T7)(R^T8)。R^T4、R^T5、R^T6、R^T7And R^T8Each independent earth surfaceRepresents a hydrogen atom, a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group.

The substituents of each of the above groups include, for example, a halogen atom, an alkyl group having 1 to 5 carbon atoms, and an alkoxy group having 1 to 5 carbon atoms. The substituent for each of the above groups also includes, for example, a substituted amino group substituted with an alkyl group having 1 to 3 carbon atoms.

In the structural formula (a-2), R^T91And R^T92Each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, and an alkoxy group having 1 to 5 carbon atoms. R^T101、R^T102、R^T111And R^T112Each independently represents a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an amino group substituted with an alkyl group having 1 to 2 carbon atoms, a substituted or unsubstituted aryl group, -C (R^T12)＝C(R^T13)(R^T14) or-CH-C (R)^T15)(R^T16)。R^T12、R^T13、R^T14、R^T15And R^T16Each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group. Tm is₁、Tm₂、Tn₁And Tn₂Each independently represents an integer of 0 to 2.

The substituents of each of the above groups include, for example, a halogen atom, an alkyl group having 1 to 5 carbon atoms, and an alkoxy group having 1 to 5 carbon atoms. The substituent of each of the above groups also includes a substituted amino group substituted with an alkyl group having 1 to 3 carbon atoms.

Of the triarylamine derivative represented by the structural formula (a-1) and the benzidine derivative represented by the structural formula (a-2), those having "-C" are preferable from the viewpoint of charge mobility₆H₄-CH＝CH-CH＝C(R^T7)(R^T8) Triarylamine derivatives and derivatives having "-CH-C (R)^T15)(R^T16) "a benzidine derivative.

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

The binder resin for the charge transport layer includes, for example, 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-maleic anhydride copolymer, silicone resin, silicone-alkyd resin, phenol resin, styrene-alkyd resin, poly-N-vinylcarbazole, or polysilane. Among them, a polycarbonate resin or a polyarylate resin is preferable as the binder resin. These binder resins may be used alone or in combination of two or more.

The blending ratio of the charge transport material to the binder resin is preferably 10:1 to 1:5 in terms of weight ratio.

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

The formation of the charge transport layer is not particularly limited, and a known formation method is used. For example, the charge transport layer is formed as follows: a coating film is formed using a charge transport layer forming coating solution obtained by adding the above components to a solvent, the coating film is dried, and the coating film is heated as necessary.

The solvent used for preparing the coating solution for forming the charge transport layer includes common organic solvents such as: aromatic hydrocarbons such as benzene, toluene, xylene or chlorobenzene; ketones such as acetone or 2-butanone; halogenated aliphatic hydrocarbons such as dichloromethane, chloroform or dichloroethane; or cyclic or branched ethers such as tetrahydrofuran or diethyl ether. These solvents are used alone or in combination of two or more.

The method of coating the charge transport layer forming coating solution on the charge generating layer includes general methods such as 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, or a curtain coating method.

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

(protective layer)

A protective layer is provided on the photosensitive layer as necessary. For example, the protective layer is provided to prevent the photosensitive layer from being chemically changed during charging or to further improve the mechanical strength of the photosensitive layer.

For this reason, the protective layer suitably employs a layer composed of a cured film (crosslinked film). These layers include, for example, layers described in the following formula 1) or 2).

1) A layer consisting of a cured film of a composition containing a charge transporting material containing a reactive group, the charge transporting material having a reactive group and a charge transporting skeleton in the same molecule (i.e., a layer containing a polymer or a crosslinked product of a charge transporting material containing a reactive group)

2) Layer consisting of a cured film of a composition containing a non-reactive charge transporting material and a non-charge transporting material containing reactive groups, the non-charge transporting material having reactive groups and no charge transporting backbone (i.e., a layer of a polymer or crosslinked product of the non-reactive charge transporting material and the non-charge transporting material containing reactive groups)

The reactive group of the charge transport material containing a reactive group includes known reactive groups such as a chain polymerizable group, an epoxy group, -OH, -OR [ wherein R represents an alkyl group]、-NH₂、-SH、-COOH、-SiR^Q1 _3-Qn(OR^Q2)_Qn[ wherein R^Q1Represents a hydrogen atom, an alkyl group or a substituted or unsubstituted aryl group. R^Q2Represents a hydrogen atom, an alkyl group or a trialkylsilyl group. Qn represents an integer of 1 to 3]。

The chain polymerizable group is not particularly limited as long as it is a functional group capable of radical polymerization, and includes, for example, a functional group having a group containing at least a carbon-containing double bond. Specifically, the chain polymerizable group includes, for example, a group containing at least one selected from a vinyl group, a vinyl ether group, a vinyl thioether group, a styryl group (vinylphenyl group), an acryloyl group, a methacryloyl group, and derivatives thereof. Among them, the chain polymerizable group is preferably 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, in view of excellent reactivity.

The charge transporting skeleton of the charge transporting material containing a reactive group is not particularly limited as long as it is a known structure in an electrophotographic photoreceptor. The charge transporting skeleton includes a skeleton derived from a nitrogen-containing hole transporting compound such as a triarylamine compound, a biphenylamine compound, or a hydrazine compound and having a structure conjugated with a nitrogen atom. Among them, a triarylamine skeleton is preferable.

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

The protective layer may contain other known additives.

The formation of the protective layer is not particularly limited, and a known formation method is used. For example, the protective layer is formed as follows: a coating film is formed using a coating solution for protective layer formation obtained by adding the above components to a solvent, the coating film is dried, and the coating film is heated as necessary.

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

The method of applying the coating solution for forming the protective layer on the photosensitive layer (e.g., charge transporting layer) includes general methods such as a dip coating method, an extrusion coating method, a wire bar coating method, a spray coating method, a blade coating method, a knife coating method, or a curtain coating method.

The film thickness of the protective layer is preferably set to, for example, 1 μm to 20 μm, more preferably 2 μm to 10 μm.

(Single layer type photosensitive layer)

The single-layer type photosensitive layer (charge generating/charge transporting layer) is a layer containing, for example, a charge generating material and a charge transporting material, and if necessary, a binder resin and other known additives. These materials are the same as those described for the charge generation layer and the charge transport layer.

In the monolayer type photosensitive layer, the content of the charge generating material is suitably 0.1 to 10% by weight, preferably 0.8 to 5% by weight, relative to the total solid content. In addition, in the monolayer type photosensitive layer, the content of the charge transporting material is suitably 5 to 50% by weight with respect to the total solid content.

The method of forming the monolayer type photosensitive layer is the same as the method of forming the charge generation layer or the charge transport layer.

The film thickness of the monolayer type photosensitive layer is, for example, suitably 5 μm to 50 μm, preferably 10 μm to 40 μm.

[ image Forming apparatus (and Process Cartridge) ]

The image forming apparatus of the present exemplary embodiment includes: the electrophotographic photoreceptor includes a charging unit that charges a surface of the electrophotographic photoreceptor, an electrostatic latent image forming unit that forms an electrostatic latent image on the charged surface of the electrophotographic photoreceptor, a developing unit that develops the electrostatic latent image formed on the surface of the electrophotographic photoreceptor with a developer containing a toner to form a toner image, and a transfer unit that transfers the toner image to a surface of a recording medium. In addition, as the electrophotographic photoreceptor, the electrophotographic photoreceptor of the present exemplary embodiment is used.

The image forming apparatus of the present exemplary embodiment is applicable to a known image forming apparatus such as: a device including a fixing unit that fixes the toner image transferred onto the surface of the recording medium; a direct transfer type device that directly transfers a toner image formed on a surface of an electrophotographic photoreceptor to a recording medium; an intermediate transfer type device that primarily transfers the toner image formed on the surface of the electrophotographic photoconductor to the surface of the intermediate transfer body, and secondarily transfers the toner image transferred to the surface of the intermediate transfer body to the surface of the recording medium; a device including a cleaning unit that cleans the surface of the electrophotographic photoconductor before charging and after toner image transfer; a device including a charge removing unit that erases charges by irradiating the surface of the electrophotographic photoconductor with charge removing light before charging and after toner image transfer; and an apparatus including an electrophotographic photoreceptor heating member that raises the temperature of the electrophotographic photoreceptor to lower the relative temperature.

In the case of using an intermediate transfer type apparatus, the transfer unit is configured to include an intermediate transfer body on the surface of which a toner image is transferred, a primary transfer unit that primarily transfers the toner image formed on the surface of the electrophotographic photoconductor to the surface of the intermediate transfer body, and a secondary transfer unit that secondarily transfers the toner image formed on the surface of the intermediate transfer body to the surface of a recording medium.

The image forming apparatus of the present exemplary embodiment may be any of a dry development type image forming apparatus and a wet development type (development type using a liquid developer) image forming apparatus.

In the image forming apparatus of the present exemplary embodiment, for example, the unit including the electrophotographic photoreceptor may be a cartridge structure (process cartridge) detachably mountable to the image forming apparatus. As the process cartridge, for example, a process cartridge including the electrophotographic photoreceptor of the present exemplary embodiment is preferably used. In addition to the electrophotographic photoreceptor, at least one selected from the group consisting of a charging unit, an electrostatic latent image forming unit, a developing unit, and a transferring unit may be included in the process cartridge.

Hereinafter, an example of the image forming apparatus of the present exemplary embodiment will be described, but the present invention is not limited thereto. The main components shown in the drawings are described, but descriptions of other components are omitted.

Fig. 2 is a schematic configuration diagram showing one example of the image forming apparatus of the present exemplary embodiment.

As shown in fig. 2, the image forming apparatus 100 of the present exemplary embodiment includes a process cartridge 300 including an electrophotographic photoconductor 7, an exposure device 9 (an example of an electrostatic latent image forming unit), a transfer device 40 (a primary transfer device), and an intermediate transfer body 50. In the image forming apparatus 100, the exposure device 9 is located at a position where the exposure device 9 irradiates light to the electrophotographic photoreceptor 7 through an opening in the process cartridge 300. The transfer device 40 is located at a position where the transfer device 40 is opposed to the electrophotographic photoreceptor 7 with the intermediate transfer body 50 therebetween. The intermediate transfer body 50 is disposed such that a part of the intermediate transfer body 50 contacts the electrophotographic photoreceptor 7. Although not shown in the drawings, a secondary transfer device that transfers the toner image on the intermediate transfer body 50 onto a recording medium (e.g., paper) is also provided. The intermediate transfer body 50, the transfer device 40 (primary transfer device), and a secondary transfer device (not shown in the figure) correspond to an example of a transfer unit.

The process cartridge 300 shown in fig. 2 integrally supports an electrophotographic photoreceptor 7, a charging device 8 (an example of a charging unit), a developing device 11 (an example of a developing unit), and a cleaning device 13 (an example of a cleaning unit) in a casing. The cleaning device 13 includes a cleaning blade 131 (an example of a cleaning member), and the cleaning blade 131 is disposed in contact with the surface of the electrophotographic photoreceptor 7. The cleaning member may be a conductive or insulating fiber member instead of the cleaning blade 131. The conductive or insulating fibrous member may be used alone or in combination with the cleaning blade 131.

Fig. 2 shows an example of an image forming apparatus including a fibrous member 132 (roller-shaped) that supplies the lubricant 14 onto the surface of the electrophotographic photoreceptor 7 and a cleaning-assisting fibrous member 133 (flat brush-shaped). These members may be provided as necessary.

The respective components of the image forming apparatus of the present exemplary embodiment will be described below.

Charging equipment

As the charging device 8, a contact type charger, such as a conductive or semiconductive charging roller, a charging brush, a charging film, a charging rubber blade, or a charging tube, is used. Further, a charger known per se, for example, a non-contact type roller charger or a high voltage corotron (scorotron) charger or corotron (corotron) charger using corona discharge is also used.

Exposure apparatus

The exposure device 9 includes, for example, an optical device that performs intended image-wise exposure of the surface of the electrophotographic photoconductor 7 with light from a semiconductor laser, LED, or liquid crystal shutter. The wavelength of the light source should be within the spectral sensitivity range of the electrophotographic photoreceptor. The mainstream semiconductor laser is a near-infrared laser having an oscillation wavelength of about 780 nm. However, the wavelength of the laser is not limited thereto, and a laser having an oscillation wavelength of about 600nm or a blue laser having an oscillation wavelength of 400nm to 450nm may also be used. Further, a surface-emitting laser light source capable of outputting multiple beams is effective for forming a color image.

Developing device

The developing device 11 includes, for example, a general developing device that performs development with a developer in a contact or non-contact manner. The developing device 11 is not particularly limited as long as it has the above-described function, and is selected according to the purpose. The developing device includes a known developing device that functions to adhere a one-component developer or a two-component developer to the electrophotographic photosensitive body 7 using, for example, a brush or a roller or the like. Among them, a developing apparatus using a developing roller that retains a developer on the surface thereof is preferable.

The developer used for the developing device 11 may be a one-component developer containing only toner, or may be a two-component developer containing toner and a carrier. The developer may be magnetic or non-magnetic. As the developer, a known developer can be used.

Cleaning equipment

As the cleaning device 13, a cleaning blade type device including a cleaning blade 131 is used.

In addition to the cleaning blade type, a brush cleaning type or a type in which development and cleaning are performed simultaneously may be employed.

-transfer device

The transfer device 40 includes a contact type transfer charger using a belt, a roller, a film, a rubber blade, or the like, and a transfer charger known per se, such as a high-voltage corotron transfer charger or a corotron transfer charger using corona discharge.

An intermediate transfer body

As the intermediate transfer member 50, a belt-like member (intermediate transfer belt) containing polyimide, polyamide-imide, polycarbonate, polyarylate, polyester, rubber, or the like, to which semiconductivity is imparted, is used. As the intermediate transfer body, a drum member may be used in addition to the belt member.

Fig. 3 is a schematic configuration diagram showing another example of the image forming apparatus of the present exemplary embodiment.

The image forming apparatus 120 shown in fig. 3 is a tandem-type multi-color image forming apparatus equipped with four process cartridges 300. In the image forming apparatus 120, four process cartridges 300 are arranged side by side on the intermediate transfer body 50. One electrophotographic photoreceptor is used for one color. The image forming apparatus 120 has the same configuration as the image forming apparatus 100, except that the image forming apparatus 120 is of a tandem type.

(other uses of dispersant-attached PTFE particles)

The dispersion agent-attached PTFE particles of the present exemplary embodiment are used as an external additive for a toner or an external additive for a powder coating material.

For example, in the case of applying PTFE particles to which a dispersant adheres to an external additive for toner particles, for example, an electrostatic charge image developing toner containing toner particles and PTFE particles to which a dispersant as an external additive adheres is used as a toner. The toner particles contain a resin (binder resin). If desired, the toner particles may contain other additives, such as colorants or release agents.

In the case where the dispersion agent-attached PTFE particles are applied to the external additive of the powder coating material, for example, a powder coating material containing powder particles and dispersion agent-attached PTFE particles as the external additive is used as the powder coating material. The powder coating contains a thermosetting resin and a thermosetting agent. If desired, the powder particles may contain further additives, for example colorants.

The foregoing descriptions of embodiments of the present invention have been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Obviously, many modifications and variations will be apparent to practitioners skilled in the art. The embodiments were chosen and described in order to best explain the principles of the invention and its practical applications, to thereby enable others skilled in the art to understand the invention for various embodiments and with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the following claims and their equivalents.

Examples

Hereinafter, the present invention will be described with reference to examples, but the present invention should not be construed as being limited thereto. All parts and percentages herein are by weight unless otherwise indicated.

< example 1>

Preparation of PTFE particles A

Commercially available PTFE particles having an average particle diameter of 3.5 μm (primary particle diameter of 0.2 μm) were washed in the following manner and then treated with a fluorine-containing dispersant to prepare PTFE particles, which were referred to as PTFE particles a.

400 parts by weight of tetrahydrofuran and 15 parts by weight of PTFE particles were charged in a high-pressure homogenizer (trade name, LA-33S, manufactured by Nanomizer Inc.) whose pressure was set at 500kg/cm²The above mixture was passed through a high-pressure homogenizer 4 times to carry out a washing treatment. The dispersion was treated with a centrifuge, and then the upper layer of the clear liquid was removed. Subsequently, tetrahydrofuran was added thereto so that the amount of tetrahydrofuran was 415 parts by weight, the mixture was subjected to a dispersion treatment using a high-pressure homogenizer, the dispersion was treated with a centrifuge, and the upper layer of the clear liquid was removed. After repeating these procedures 3 times again, 1.5 parts by weight of GF400 (a surfactant made of at least methacrylate having a fluorinated alkyl group as a polymerization component, manufactured by Toagosei co., ltd.) was added thereto as a fluorine-containing dispersant, then tetrahydrofuran was added thereto so that the amount of tetrahydrofuran was 415 parts by weight, the mixture was subjected to dispersion treatment with a high-pressure homogenizer, and then the solvent was distilled off under reduced pressure. After drying, the resulting granules were pulverized in a mortar. The resulting particles are referred to as PTFE particles a.

Measurement of the PFOA content in PTFE particles A-

The PFOA content in the PTFE particle A was measured according to the method described above, and as a result, it was found to be 5 ppb.

Preparation of the PTFE composition L-A

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

Evaluation of PTFE composition L-A

The dispersion state of PTFE in the obtained PTFE composition L-A was evaluated using a laser diffraction particle size distribution measuring apparatus (Mastersizer 3000 manufactured by Malvern Instruments Ltd.), and as a result, it was found that the average particle diameter was 0.22. mu.m.

Preparation and evaluation of PTFE layered Material F-A

The PTFE composition L-A was coated on a glass substrate using a gap coater and heated at 130 ℃ for 45 minutes to prepare a PTFE layered material F-A having a film thickness of 5 μm. The PTFE particles in the resulting layered material had an average particle diameter of 0.23. mu.m.

Preparation of electrophotographic photoreceptor A-

Photoreceptor a was prepared in the following manner.

Formation of the primer layer

100 parts of zinc oxide (manufactured by TAYCA Corp., average particle diameter 70nm, specific surface area 15 m)²(g)) and mixed with 500 parts of tetrahydrofuran, 1.3 parts of a silane coupling agent (KBM503, manufactured by Shin-Etsu chemical co., ltd., and stirred for 2 hours. Then, tetrahydrofuran was distilled off under reduced pressure, and baked at 120 ℃ for 3 hours to obtain silane coupling agent surface-treated zinc oxide.

110 parts of zinc oxide was subjected to surface treatment, and 500 parts of tetrahydrofuran was stirred and mixed, to which a solution obtained by dissolving 0.6 part of alizarin in 50 parts of tetrahydrofuran was added, and stirred at 50 ℃ for 5 hours. Then, the alizarin-applied zinc oxide was separated by filtration under reduced pressure, and dried at 60 ℃ under reduced pressure to obtain alizarin-applied zinc oxide.

60 parts of alizarin-added zinc oxide, 13.5 parts of a curing agent (blocked isocyanate, Sumidur 3175, manufactured by Sumitomo Bayer Urethane co., ltd.), 15 parts of a butyral resin (S-LEC BM-1, manufactured by sekisui chemical co., ltd.) and 85 parts of methyl ethyl ketone were mixed to obtain a mixed solution. 38 parts of the mixed solution and 25 parts of methyl ethyl ketone were mixed and passed through a mixer having a diameter ofThe glass beads were dispersed for 2 hours by a sand mill to obtain a dispersion.

To the resulting dispersion liquid were added 0.005 parts of dioctyltin dilaurate as a catalyst and 45 parts of silicone resin particles (tosearl 145, manufactured by Momentive Performance Materials Japan inc.) to obtain a coating solution for an undercoat layer. The coating solution for undercoat layer was applied to an aluminum substrate having a diameter of 47mm, a length of 357mm and a wall thickness of 1mm by a dip coating method, and dried and cured at 170 ℃ for 30 minutes to obtain an undercoat layer having a thickness of 25 μm.

Formation of charge generation layer

1 part of hydroxygallium phthalocyanine (having strong diffraction peaks at bragg angles (2 θ ± 0.2 °) of 7.5 °, 9.9 °, 12.5 °, 16.3 °, 18.6 °, 25.1 ° and 28.3 ° in X-ray diffraction) was mixed with 1 part of polyvinyl butyral (S-LEC BM-S manufactured by sekisui chemical co., ltd.) and 80 parts of n-butyl acetate, and the mixture was dispersion-treated with glass beads by a paint stirrer for 1 hour to prepare a coating solution for a charge generation layer. The charge generation layer was dip-coated with the coating solution on the undercoat layer formed on the conductive substrate, and dried by heating at 100 ℃ for 10 minutes to form a charge generation layer having a film thickness of 0.15 μm.

Formation of charge transport layer

The above PTFE composition L-a was coated on the above charge generation layer by a dip coating method, and heated at 130 ℃ for 45 minutes to form a charge transport layer having a thickness of 13 μm.

Each photoreceptor was produced by the above procedure.

Evaluation of electrophotographic photoreceptor A-

The photoreceptor thus obtained was used for the following evaluation.

Visual evaluation

The surface of the obtained photoreceptor (surface of the charge transport layer) was visually observed. The evaluation criteria are as follows.

A: no streaks were observed.

B: slight streak-like defects were observed.

C: significant streak-like defects were observed.

Evaluation of image quality

The obtained photoreceptor was loaded in an image forming apparatus (ApeosPort C4300, manufactured by Fuji Xerox co., ltd.). With this apparatus, a 5% halftone image was output on 100 sheets of a4 paper. The image defects were evaluated by observing the images on the first and 100 th sheets. The evaluation criteria are as follows.

A: no image defects were observed.

B: slight image defects (level without any problems) were observed with a magnifying glass.

C: image defects were visually observed.

D: significant streak-like image defects were observed.

< example 2>

Preparation of PTFE particles B

Commercially available PTFE particles having an average particle diameter of 4.5 μm (primary particle diameter of 0.2 μm) were washed in the same manner as in example 1 and then treated with a fluorine-containing dispersant to produce PTFE particles, which were referred to as PTFE particles B.

Measurement of the PFOA content in PTFE particles B-

The PFOA content in the PTFE particle B was measured in the same manner as described above for the PTFE particle A, and as a result, it was found to be 0 ppb.

Preparation of the PTFE compositions L-B

PTFE compositions L-B were prepared by the same procedure as in example 1, except that the PTFE particles A were changed to PTFE particles B.

Evaluation of PTFE compositions L-B

The same evaluation as in example 1 was conducted except that the PTFE composition L-A was changed to a PTFE composition L-B. The results obtained are shown in table 1.

Preparation and evaluation of PTFE layered Material F-B

The preparation and evaluation of the PTFE layered material F-B were carried out by the same procedures as in example 1 except that the PTFE composition L-A was changed to the PTFE composition L-B. The results obtained are shown in table 1.

Preparation of the electrophotographic photoreceptor B-

An electrophotographic photoreceptor B was produced by the same procedure as in example 1 except that the PTFE composition L-a was changed to the PTFE composition L-B.

Evaluation of electrophotographic photoreceptor B-

The obtained electrophotographic photoreceptor B was evaluated in the same manner as in example 1. The results obtained are shown in table 1.

< example 3>

In the production of PTFE particles a of example 1, the PTFE particles a are washed so that the total amount of PFOA is 25ppb, and then treated with a fluorine-containing dispersant to produce PTFE particles, which are referred to as PTFE particles C.

Subsequently, the production and evaluation of PTFE compositions L to C, the production and evaluation of PTFE layered materials F to C, and the production and evaluation of an electrophotographic photoreceptor C were carried out in the same manner as in example 1 except that PTFE particles C were used in place of the PTFE particles A. The results obtained are shown in table 1.

< comparative example 1>

In the production of PTFE particles a of example 1, the PTFE particles a are washed so that the total amount of PFOA is 30ppb, and then treated with a fluorine-containing dispersant to produce PTFE particles, which are referred to as PTFE particles E.

Subsequently, the production and evaluation of PTFE compositions L to E, the production and evaluation of PTFE layered materials F to E, and the production and evaluation of an electrophotographic photoreceptor E were carried out in the same manner as in example 1 except that PTFE particles E were used in place of PTFE particles A. The results obtained are shown in table 1.

< example 4>

(preparation and evaluation of powder coating)

Using the PTFE particles a in example 1 as an external additive, a powder coating was prepared in the following manner.

Preparation of a composite Dispersion of polyester resin and curing agent (E1)

A mixed solvent of 180 parts of ethyl acetate and 80 parts of isopropyl alcohol was charged into a jacketed 3-liter reaction vessel (BJ-30N, manufactured by Tokyo Rikakikai Co, ltd.) provided with a condenser, a thermometer, a dripping device and an anchor blade while the reaction vessel was kept in a water circulation type thermostatic bath at 40 ℃, and then the following composition was charged thereinto.

Polyester resin (PES1) [ polycondensate of terephthalic acid/ethylene glycol/neopentyl glycol/trimethylolpropane (molar ratio 100/60/38/2 (mol%), glass transition temperature 62 ℃, acid value (Av) 12mgKOH/g, hydroxyl value (OHv) 55mgKOH/g, weight average molecular weight (Mw) 12,000, number average molecular weight (Mn) 4,000 ]: 240 parts

Blocked isocyanate curing agent (VESTAGON B1530, manufactured by Evonik Industries AG): 60 portions of

Benzoin: 1.5 parts of

Acrylic oligomer (ACRONAL 4F, manufactured by BASF SE): 3 portions of

After the composition was added, the mixture was stirred at 150rpm using a three-one motor to dissolve it, thereby preparing an oil phase. A mixed solution of 1 part of a 10 wt% aqueous ammonia solution and 47 parts of a 5 wt% aqueous sodium hydroxide solution was added dropwise to the oil phase over 5 minutes while stirring, mixed for 10 minutes, and then 900 parts of ion-exchanged water was further added dropwise thereto at a rate of 5 parts/minute to perform phase inversion, thereby obtaining an emulsion.

Immediately, 800 parts of the obtained emulsion and 700 parts of ion-exchanged water were put into a 2-liter eggplant type flask, and placed in an evaporator (manufactured by Tokyo Rikakikai Co, ltd.) provided with a vacuum control unit through a trap bulb (trap bulb). The eggplant type flask was heated in a hot water bath at 60 ℃ while being rotated, and the solvent was removed by carefully reducing the pressure to 7kPa while being boiled. When the recovery amount of the solvent was 1100 parts, the pressure was returned to normal pressure (1 atm), and the eggplant type flask was cooled with water to obtain a dispersion. The resulting dispersion had no solvent odor. The volume average particle diameter of the resin particles in the dispersion was 145 nm. Thereafter, an anionic surfactant (Dowfax 2a1, manufactured by The Dow Chemical Company, amount of effective component 45 wt%) was added and mixed so that The amount of The effective component thereof was 2 wt% with respect to The amount of The resin component in The dispersion, and ion-exchanged water was added thereto to adjust so that The solid concentration was 25 wt%. The resulting dispersion is referred to as a polyester resin and curing agent composite dispersion (E1).

Preparation of the white pigment Dispersion (W1)

Titanium oxide (a-220, manufactured by Ishihara Sangyo Kaisha, ltd.): 100 portions of

Anionic surfactant (Neogen RK, manufactured by Dai-ichi Kogyo Seiyaku co., ltd.): 15 portions of

Ion-exchanged water: 400 portions of

0.3mol/l nitric acid: 4 portions of

The above components were mixed and dissolved, and then dispersed for 3 hours using a high-pressure impact disperser altizer (HJP 30006, manufactured by Sugino Machine ltd.) to prepare a white pigment dispersion liquid in which titanium oxide was dispersed. As a result of measurement using a laser diffraction particle size distribution measuring apparatus, the volume average particle diameter of titanium oxide in the dispersion was 0.28. mu.m, and the solid content ratio of the white pigment dispersion was 25%.

Preparation of white powder particles (PC1) -

Polyester resin and curing agent composite dispersion (E1): 180 parts (solid 45 parts)

White pigment dispersion (W1): 160 parts (solid is 40 parts)

Ion-exchanged water: 200 portions of

The above components were mixed and dissolved in a stainless steel round bottom flask by using a homogenizer (Ultra-Turrax T50, manufactured by IKA Works, inc.). Then, the pH was adjusted to 3.5 using a 1.0 wt% aqueous nitric acid solution. To this was added 0.50 part of a 10% by weight aqueous solution of polyaluminum chloride, and the dispersion operation was continuously carried out using an Ultra-Turrax.

A stirrer and a mantle heater were provided, the temperature was raised to 50 ℃ while the number of revolutions of the stirrer was adjusted so that the slurry was sufficiently stirred, the slurry was maintained at 50 ℃ for 15 minutes, then the particle diameter of the agglomerated particles was measured with a TA-II type Coulter counter (manufactured by Beckman Coulter, inc., pore diameter: 50 μm), and when the volume average particle diameter was 5.5 μm, 60 parts of a polyester and curing agent composite dispersion (E1) as a shell was slowly charged into the flask (charged into the shell).

After the shell was put into the flask, the flask was kept for 30 minutes, and then the pH was set to 7.0 using a 5% aqueous sodium hydroxide solution. Thereafter, the temperature was raised to 85 ℃ and maintained for 2 hours.

After the reaction was complete, the solution in the flask was cooled and filtered to give a solid. Then, the solid matter was washed with ion-exchanged water, and subjected to solid-liquid separation by Nutsche type suction filtration to obtain the solid matter again.

Subsequently, the solids were redispersed in 3 liters of ion-exchanged water at 40 ℃ and stirred and washed at 300rpm for 15 minutes. The washing operation was repeated 5 times, and the solid obtained by solid-liquid separation by Nutsche type suction filtration was vacuum-dried for 12 hours to obtain core-shell type white powder particles (PC 1).

As a result of measurement of the particle diameter of the white powder particles (PC1), the volume average particle diameter D50v was 6.8 μm, the volume particle diameter distribution index GSDv was 1.24, and the average circularity was 0.97.

Preparation of white powder coatings

100 parts of white powder particles (PC1), 0.6 parts of silica particles (Aerosil RX200, manufactured by Nippon Aerosil co., ltd.) as an external additive, and 3 parts of dispersant-attached PTFE particles of each example as an external additive were mixed for 10 minutes using a henschel mixer at a peripheral speed of 32m/s, and then coarse particles were removed by using a sieve having a mesh size of 45 μm to obtain a white powder coating.

Evaluation-

The following evaluation was performed using the obtained white powder coating.

The powder coating was placed in a corona gun XR4-110C manufactured by Asahi Sunac Corp.

Corona gun XR4-110C manufactured by Asahi Sunac Corp. vs. 30cm x 30cm mirrorThe square test plate of the surface-polished aluminum plate was slid vertically and horizontally at a distance of 30cm from the front surface of the panel (distance between the panel and the discharge port of the corona gun) to discharge the powder coating and electrostatically adhere it to the panel, thereby forming an adhesion layer. The voltage applied to the corona gun was set to 80kV, the input air pressure was set to 0.55MPa, the discharge rate was set to 200 g/min, and the amount of powder paint adhering to the panel was set to 50g/m²、90g/m²、180g/m²Or 220g/m²To perform 4 coats.

Subsequently, each panel was put into a high-temperature chamber set at 180 ℃ and heated (baked) for 30 minutes.

The obtained coating film was evaluated by a touch method and visual observation. The evaluation criteria are as follows.

A: no problems were found by touch method and visual observation.

B: slight unevenness (level without any problems) was recognized by visual observation.

C: highlights (levels without any problems) were identified by tactile methods.

D: the inhomogeneities were identified by visual observation and the highlights were identified by tactile methods.

< examples 5 and 6 and comparative example 2>

(preparation and evaluation of powder coating)

Powder coatings were prepared and evaluated in the same manner as in example 4, except that the PTFE particles B to E in examples 2 and 3 and comparative example 1 were used.

The above examples are listed in tables 1 and 2.

TABLE 2

As can be seen from the results shown above, in the examples, satisfactory results were obtained in both the evaluation of the photoreceptor and the evaluation of the powder coating, as compared with the comparative examples.

Therefore, it can be seen that the PTFE particle dispersion of the present exemplary embodiment (and the dispersant-attached PTFE particles) has high retention of the dispersed state even if the state of the mixed components is changed.

Claims

1. A dispersant-attached polytetrafluoroethylene particle having a dispersant having fluorine atoms attached to the surface thereof, wherein the content of perfluorooctanoic acid is 0ppb to 25ppb with respect to the polytetrafluoroethylene particle.

2. The dispersant-attached polytetrafluoroethylene particles of claim 1 having an average particle size of from 0.2 μm to 4.5 μm.

3. The dispersant-attached polytetrafluoroethylene particles according to claim 1 or 2, wherein the dispersant having a fluorine atom is a polymer obtained by homopolymerization or copolymerization of a polymerizable compound having a fluorinated alkyl group.

4. The dispersant-attached polytetrafluoroethylene particle according to claim 3, wherein said polymer obtained by homopolymerization or copolymerization of a polymerizable compound having a fluorinated alkyl group is a fluorinated alkyl-containing polymer having a structural unit represented by the following Formula (FA), or a fluorinated alkyl-containing polymer having a structural unit represented by the following Formula (FA) and a structural unit represented by the following Formula (FB):

wherein, in said Formulae (FA) and (FB), R^F1、R^F2、R^F3And R^F4Each independently represents a hydrogen atom or an alkyl group; x^F1Represents an alkylene chain, a halogen-substituted alkylene chain, -S-, -O-, -NH-or a single bond; y is^F1Represents an alkylene chain, a halogen-substituted alkylene chain, -C_fxH_2fx-1(OH)) -or a single bond；Q^F1represents-O-or-NH-; fl, fm and fn each independently represent an integer of 1 or more; fp, fq, fr and fs each independently represents an integer of 0 or 1 or more; ft represents an integer of 1 to 7; fx represents an integer of 1 or more.

5. The dispersant-attached polytetrafluoroethylene particles according to any one of claims 1 to 4, wherein the content of the dispersant having fluorine atoms is 0.5 to 10% by weight relative to the polytetrafluoroethylene particles.

6. The dispersant-attached polytetrafluoroethylene particles according to claim 5, wherein the content of the dispersant having fluorine atoms is 1 to 7% by weight relative to the polytetrafluoroethylene particles.

7. A composition comprising polytetrafluoroethylene particles and a dispersing agent having fluorine atoms, wherein the content of perfluorooctanoic acid is 0ppb to 25ppb with respect to the polytetrafluoroethylene particles.

8. The composition of claim 7 wherein the polytetrafluoroethylene particles have an average particle size of from 0.2 to 4.5 μm.

9. The composition of claim 7 or 8, which is liquid or solid.

10. A layered material comprising polytetrafluoroethylene particles and a dispersing agent having fluorine atoms, wherein the content of perfluorooctanoic acid is 0ppb to 25ppb with respect to the polytetrafluoroethylene particles.

11. The layered material of claim 10, wherein said polytetrafluoroethylene particles have an average particle size of 0.2 μm to 4.5 μm.

12. An electrophotographic photoreceptor comprising a conductive substrate and a photosensitive layer, wherein an outermost surface layer of the electrophotographic photoreceptor is a layer comprising the layered material according to claim 10 or 11.

13. A process cartridge comprising the electrophotographic photoreceptor according to claim 12, wherein the process cartridge is detachably mountable to an image forming apparatus.

14. An image forming apparatus, comprising: the electrophotographic photoreceptor of claim 12, a charging unit that charges a surface of the electrophotographic photoreceptor, an electrostatic latent image forming unit that forms an electrostatic latent image on the charged surface of the electrophotographic photoreceptor, a developing unit that develops the electrostatic latent image formed on the surface of the electrophotographic photoreceptor with a developer containing a toner to form a toner image, and a transfer unit that transfers the toner image to a surface of a recording medium.