JP2021189207A - Electrophotographic photoreceptor, electrophotographic image forming method, and electrophotographic image forming apparatus - Google Patents

Abstract

To provide an electrophotographic photoreceptor that is excellent in mechanical strength including wear resistance and scratch resistance and can maintain satisfactory cleanability for a long period, an electrophotographic image forming method, and an electrophotographic image forming apparatus.SOLUTION: The ratio of organic resin particle 10% displacement hardness/outermost surface layer hardness in an outermost surface layer containing organic resin particles is made to fall into a certain range.SELECTED DRAWING: Figure 1

Description

The present invention relates to an electrophotographic photosensitive member, an electrophotographic image forming method, and an electrophotographic image forming apparatus.
More specifically, the present invention relates to an electrophotographic photosensitive member, an electrophotographic image forming method, and an electrophotographic image forming apparatus, which are excellent in mechanical strength such as abrasion resistance and scratch resistance and can maintain good cleaning property for a long period of time.

In recent years, further high durability and high image quality have been desired for image formation by electrophotographic copying machines and printers.

In particular, with regard to high durability, there are increasing demands for contributing to the realization of a sustainable society, and mechanical strength such as wear resistance and scratch resistance, which are the most important factors that determine the durable life of a photoconductor. Is especially important.

On the other hand, with regard to high image quality, it is necessary to maintain high image quality for a long period of time, and it is also important to maintain good cleaning performance that affects image quality.

Therefore, it is known that the curable surface layer contains organic resin particles in order to improve the wear resistance and scratch resistance that lead to the extension of the life of the photoconductor and also to improve the cleanability of the photoconductor. ..

For example, Patent Document 1 discloses that the surface layer of a photoconductor contains organic resin fine particles and metal oxide fine particles made of a resin containing melamine, benzoguanamine, or the like as a polymerization component in a cured resin.

Further, in Patent Document 2, a binder resin containing a resin obtained by polymerizing metal oxide particles and a crosslinkable polymerizable compound on the surface layer of the photoconductor, and a styrene-acrylic resin, polystyrene, or silicone. It is disclosed that the organic resin particles made of the same resin or the like are contained.

Further, in Patent Document 3, an organic resin particle such as an acrylic resin and a melamine resin on the surface layer, a compound having a monovalent hydrocarbon group having 7 or more carbon atoms and a polymerizable functional group in the same molecule, and a polymerizable functional group are used. It is disclosed that a hole transporting compound having a group is contained.

However, when the hardness difference between the organic resin particles (particularly melamine resin) and the other surface layer resin portion is large, the organic resin particles (especially melamine resin) are easily separated due to the difference in the depletion rate between the two, and the cleaning property is maintained for a long period of time. There was a problem that it could not be done.

Japanese Unexamined Patent Publication No. 2015-72425 Japanese Unexamined Patent Publication No. 2014-219460 Japanese Unexamined Patent Publication No. 2019-45862

The present invention has been made in view of the above problems and situations, and the problem to be solved thereof is an electrophotographic that is excellent in mechanical strength such as abrasion resistance and scratch resistance and can maintain good cleaning property for a long period of time. It is an object of the present invention to provide a photoconductor, an electrophotographic image forming method, and an electrophotographic image forming apparatus.

In the process of investigating the cause of the above problem in order to solve the above problems, the present inventor keeps the ratio of the organic resin particles of the outermost layer containing the organic resin particles to 10% displacement hardness / outermost layer hardness within a certain range. We have found that by storing the particles, they have excellent mechanical strength such as abrasion resistance and scratch resistance, and can maintain good cleaning properties for a long period of time, and have arrived at the present invention.
That is, the above-mentioned problem according to the present invention is solved by the following means.

1. 1. An electrophotographic photosensitive member having a curable outermost surface layer on at least the photosensitive layer.
The outermost layer contains at least organic resin particles, and
An electrophotographic feature in which the ratio of the 10% displacement hardness of the organic resin particles to the outermost layer hardness (10% displacement hardness of the organic resin particles / outermost surface layer hardness) is in the range of 0.15 to 0.55. Photoreceptor.

2. 2. An electrophotographic photosensitive member having a 10% displacement hardness of the organic resin particles in ^{the range of 45 to 80 N / mm 2} and a surface hardness of the outermost layer in ^{the range of 150 to 300 N / mm 2.}

3. 3. The first surface layer is a cured product formed of a composition containing at least a polymerizable monomer, conductive fine particles having a polymerizable group, and a charge transporting substance having a polymerizable group. The electrophotographic photosensitive member according to the item or item 2.

4. The electrophotographic photosensitive member according to any one of items 1 to 3, wherein the outermost surface hardness is adjusted by a radical scavenger.

5. A method for forming an electrophotographic image, which comprises using the electrophotographic photosensitive member according to any one of the items 1 to 4.

6. An electrophotographic image forming apparatus comprising the electrophotographic photosensitive member according to any one of the items 1 to 4.

By the above means of the present invention, an electrophotographic photosensitive member, an electrophotographic image forming method, and an electrophotographic image forming apparatus, which are excellent in mechanical strength such as abrasion resistance and scratch resistance and can maintain good cleaning property for a long period of time, are provided. Can be provided.

Although the mechanism of expression or the mechanism of action of the effect of the present invention has not been clarified, it is inferred as follows.

Generally, the hardness of the outermost layer of the photoconductor is often in the range of ^{150 to 300 N / mm 2.}
If the hardness of the outermost layer is too large, the wear is extremely small, so that the image flow during image printing cannot be suppressed, and if the hardness of the outermost layer is too small, the wear is large, and the life of the photoconductor cannot be extended.

Here, it is known that the cleaning property is improved by imparting unevenness to the surface shape of the outermost layer by using organic resin particles.
However, when the hardness difference between the organic resin particles and other resin parts (including compounds such as resin and CTM) is large, the organic resin particles are easily detached and worn due to the difference in the depletion rate between the two, and the cleaning property can be maintained for a long period of time. The problem is that it cannot be done.

Generally, the external additive released from the toner wears the outermost layer as it passes through the cleaning blade while receiving a vertical load from the cleaning blade.

Therefore, the greater the hardness of the external additive particles, the less the wear of the external additive particles themselves.
Further, as the hardness of the outermost layer increases, the degree of wear of the outermost layer also decreases, and as a result, the wear of other resin portions also decreases.

As a result of diligent studies, the wear degree of the external additive particles themselves (10% displacement hardness of the particles) and the wear degree of other resin parts (universal hardness of the outermost layer excluding organic resin particles) are particularly strong in the compression direction. It was found that when the ratio of the particles is in the range of 0.15 to 0.55, the mechanical strength such as abrasion resistance and scratch resistance is excellent, and good cleaning property can be maintained for a long period of time, and the present invention has been made.

Cross-sectional view showing an example of the configuration of the electrophotographic photosensitive member of the present invention. Schematic diagram showing an example of the overall configuration of a tandem type electrophotographic image forming apparatus including the electrophotographic photosensitive member of the present invention. Schematic diagram for explaining the evaluation method of the photoconductor (test image consisting of vertical strip-shaped solid images with 10% coverage) Schematic diagram for explaining the evaluation method of the photoconductor (test image consisting of horizontal band-shaped solid images with 40% coverage)

The electrophotographic photosensitive member of the present invention is an electrophotographic photosensitive member having a curable outermost surface layer on at least the photosensitive layer, and the outermost surface layer contains at least organic resin particles and the organic resin particles. The ratio of the 10% displacement hardness to the outermost layer hardness (10% displacement hardness of the organic resin particles / outermost surface layer hardness) is in the range of 0.15 to 0.55.
This feature is a technical feature common to or corresponding to each of the following embodiments.

In an embodiment of the present invention, the 10% displacement hardness of the organic resin particles is in ^{the range of 45 to 80 N / mm 2} , and the outermost layer hardness is in the range of ^{150 to 300 N / mm 2.} It is preferable from the viewpoint of suppressing the image flow during image printing and achieving a long life of the photoconductor.

Further, it is reactive that the outermost layer is a cured product formed of a composition containing at least a polymerizable monomer, conductive fine particles having a polymerizable group, and a charge transporting substance having a polymerizable group. It is preferable from the viewpoint of enhancing the effect and expressing the effect.

It is preferable that the hardness of the outermost layer is adjusted by a radical scavenger from the viewpoint of controlling the hardness of the outermost layer within an appropriate range.

The electrophotographic photosensitive member of the present invention is suitably used for an electrophotographic image forming method.

Further, the electrophotographic photosensitive member of the present invention is suitably used for an electrophotographic image forming apparatus.

Hereinafter, the present invention, its constituent elements, and modes and embodiments for carrying out the present invention will be described. In the present application, "~" is used to mean that the numerical values described before and after it are included as the lower limit value and the upper limit value.

<Electrophotograph photosensitive member>
The electrophotographic photosensitive member of the present invention is a laminated electrophotographic photosensitive member having a curable outermost layer on at least the photosensitive layer, and the outermost surface layer contains at least organic resin particles and the organic. The ratio of the 10% displacement hardness of the resin particles to the outermost layer hardness (10% displacement hardness of the organic resin particles / outermost surface layer hardness) is in the range of 0.15 to 0.55.

[Basic configuration of electrophotographic photosensitive member]
FIG. 1 is a cross-sectional view showing an example of the configuration of the electrophotographic photosensitive member of the present invention.
FIG. 1A is a cross-sectional view showing an electrophotographic photosensitive member 101A having the first configuration, in which an intermediate layer 103 is formed on a conductive support 102, and a photosensitive layer 104 is provided on the intermediate layer 103. The outermost layer 105 according to the present invention is formed on the surface thereof, and the outermost layer 105 contains at least organic resin particles, and has a 10% displacement hardness and an outermost layer hardness of the organic resin particles. The ratio (10% displacement hardness of organic resin particles / outermost layer hardness) is in the range of 0.15 to 0.55.

Further, FIG. 1B is a cross-sectional view showing the electrophotographic photosensitive member 101B having the second configuration, in which the intermediate layer 103 is formed on the conductive support 102, and the charge generation layer 106 and the charge generation layer 106 are formed on the intermediate layer 103. The photosensitive layer 104 composed of the charge transport layer 107 is formed, and the outermost layer 105 according to the present invention is formed on the outermost surface. The outermost layer 105 contains at least organic resin particles. Moreover, the ratio of the 10% displacement hardness of the organic resin particles to the outermost layer hardness (10% displacement hardness of the organic resin particles / outermost surface layer hardness) is in the range of 0.15 to 0.55.
The details of the main components of the electrophotographic photosensitive member of the present invention will be described below.

1. 1. Outer surface layer The outermost layer according to the present invention contains at least organic resin particles, and the ratio of the 10% displacement hardness of the organic resin particles to the outermost layer hardness (10% displacement hardness of organic resin particles / outermost layer). Hardness) is in the range of 0.15 to 0.55.

Here, the 10% displacement hardness of the organic resin particles is the time when the displacement amount reaches 10% of the particle diameter when a test force is applied to one particle at a load speed of 0.223 mN / sec in the compression test. It is a test force.
The hardness of the outermost layer according to the present invention is universal hardness (N / mm ² ).

The fact that the 10% displacement hardness of the organic resin particles is in ^{the range of 45 to 80 N / mm 2} and the outermost layer hardness is in ^{the range of 150 to 300 N / mm 2} suppresses image flow during image printing. However, it is preferable from the viewpoint of achieving a long life of the photoconductor.

Further, it is reactive that the outermost layer is a cured product formed of a composition containing at least a polymerizable monomer, conductive fine particles having a polymerizable group, and a charge transporting substance having a polymerizable group. It is preferable from the viewpoint of enhancing the effect and expressing the effect.

It is preferable that the hardness of the outermost layer is prepared by a radical scavenger from the viewpoint of controlling the hardness of the outermost layer within an appropriate range.

(1.1) Organic resin particles The 10% displacement hardness of the organic resin particles according to the present invention depends on the type of the organic resin particles contained in the outermost layer, the number average primary particle diameter, the surface modification method, the shape, the content ratio, and the like. Can be controlled.
Examples of the organic resin particles used in the present invention include amino resin particles (for example, melamine resin particles and benzoguanamine resin particles, and melamine particles containing and cured of a monomer selected from acetguanamine, guanamine, and CTU guanamine) and fluororesins. Examples thereof include particles, silicone resin particles, acrylic resin particles, olefin resin particles (for example, polystyrene resin particles, etc.), phenol resin, and other heterogeneous mixed resin particles. From the viewpoint of exhibiting the effects of the present invention, melamine resin particles are used. preferable.

The melamine resin particles are resin particles containing at least a structural unit derived from melamine, and specific examples thereof include a polycondensate of melamine and formaldehyde, and a polycondensate of melamine, benzoguanamine, and formaldehyde. Will be.

Fluororesin particles include polytetrafluoroethylene (PTFE), polytrifluoroethylene, polyvinylidene fluoride, polyvinyl fluoride, polyfluoroalkyl vinyl ether, polychlorotrifluoroethylene, polyhexafluoropropylene, polydifluorodichloroethylene or its own. Examples thereof include copolymers.

Examples of the silicone resin particles include organopolysiloxane, for example, methyl hydrogen polysiloxane, dimethylpolysiloxane, methoxypolysiloxane, methylphenylpolysiloxane, cyclohexylpolysiloxane and the like.

Examples of the acrylic resin particles include a polymer of an acrylic acid ester or a methacrylic acid ester, a copolymer of an acrylic acid ester or a methacrylic acid ester and styrene, and the like, and may have a crosslinked structure.

Examples of the polystyrene resin particles include a polymer of styrene, which may have a crosslinked structure.

Examples of the benzoguanamine resin particles include a polycondensate of benzoguanamine and formaldehyde.

Examples of the olefin resin include polyethylene, polypropylene, polybutene, polyhexene and the like.

Specific examples of commercially available organic resin particles include the following compounds.

Melamine resin particles: Epostal S, Epostal S6, Epostal S12, Epostal M30 (above, manufactured by Nippon Shokubai Co., Ltd.), Optobeads 2000M, Optobeads 3500M (above, manufactured by Nissan Chemical Industries, Ltd.), etc.

Fluororesin particles: KTL-1N (manufactured by Kitamura Co., Ltd.), Polymist F5A (manufactured by Solvay Specialty Polymers Japan Co., Ltd.), etc.

Silicone resin particles: Tospearl XC99-A8808, Tospearl 120 (manufactured by Momentive Performance Materials Japan, Inc.), KMP-605 (manufactured by Shin-Etsu Chemical Co., Ltd.), etc.

Acrylic resin particles: E-Poster MA1002, E-Poster MA1004, E-Poster MA2003 (above, manufactured by Nippon Shokubai Co., Ltd.), FS102, FS201 (above, manufactured by Nippon Paint Industrial Coatings Co., Ltd.), etc.

Polystyrene resin particles: SX-130H, KSR-3A (all manufactured by Soken Chemical Co., Ltd.), etc.

Benzoguanamine resin particles: Epostal MS (manufactured by Nippon Shokubai Co., Ltd.), etc.
Can be mentioned.

(1.1.1) Melamine Resin Particles Melamine resin particles are preferable as the organic resin particles used in the present invention.
When the melamine resin particles are used, it is possible to suppress the particles from falling off during durability from the viewpoint of compatibility with the resin, so that good cleaning properties can be maintained for a long period of time.

(1.1.2) Number Average Primary Particle Diameter of Organic Resin Particles The number average primary particle diameter of the organic resin particles used in the present invention is in the range of 0.08 to 3.00 μm.
The number average primary particle diameter of the organic resin particles is preferably in the range of 0.20 to 2.50 μm, and more preferably in the range of 0.30 to 1.50 μm.

When the number average primary particle diameter of the organic resin particles is 0.20 μm or more, good cleaning property can be obtained, and when it is 0.30 μm or more, even better cleaning property can be obtained.

On the other hand, when the number average primary particle diameter of the organic resin particles is 2.50 μm or less, the curing inhibition is further suppressed when the outermost layer is formed, and when the number average primary particle diameter is 1.50 μm or less, the curing inhibition is further suppressed, which is good. Scratch resistance can be obtained.
The number average primary particle size of the organic resin particles is defined as the number average primary particle size measured by the following method.

First, a magnified photograph (organic resin particles, etc.) of a sample (organic resin particles, etc.) taken at a magnification of 30,000 times is taken into a scanner by a scanning electron microscope (manufactured by JEOL Ltd.).

Next, from the obtained photographic images, 300 organic resin particle images excluding the aggregated organic resin particles were randomly selected from the automatic image processing analysis system Luzex AP Software Ver. A binarization process is performed using 1.32 (manufactured by NIRECO CORPORATION) to calculate the horizontal ferret diameter of each of the organic resin particle images.

Then, the average value of each horizontal ferret diameter of the organic resin particle image is calculated and used as the number average primary particle diameter.

Here, the horizontal ferret diameter means the length of the side parallel to the x-axis of the circumscribed rectangle when the organic resin particle image is binarized.

(11.3) Surface-modifying agent for organic resin particles The organic resin particles of the present invention may be surface-modified with a surface-modifying agent. The surface modification treatment is possible by subjecting the untreated organic resin particles, which are the raw materials, to the surface modification treatment with a surface modifier.

The organic resin particles surface-modified with the surface modifier are considered to be surface-coated resin particles containing a chemical species (coating layer) derived from the surface modifier and the organic resin particles. The surface-modified organic resin particles may have a chemical species (coating layer) derived from the surface modifier on at least a part of the surface thereof.

In the present invention, the surface modifying agent applied to the surface modifying treatment of the organic resin particles is not particularly limited, and conventionally known ones can be used. Specific examples of the surface modifier include a silane coupling agent, a titanium coupling agent, a fluorine-based surface modifier, a surface modifier having a silicone chain, and the like.

The surface modifier can be used alone or in combination of two or more. Further, the surface modifier may be a synthetic product or a commercially available product.

(1.1.4) Shape of Organic Resin Particles The shape of the organic resin particles is not particularly limited, and examples thereof include a spherical shape, an elliptical cross section, a needle shape, a disc shape, and an indefinite shape. From the viewpoint of improving cleanability, a spherical shape is preferable.

(1.1.5) Content ratio of organic resin particles The organic resin particles are preferably contained in a ratio of 3 to 50 parts by mass, more preferably 3 to 30 parts by mass with respect to 100 parts by mass of the cured resin. be. When the content ratio of the organic resin particles is within the above range, good cleaning properties can be ensured.

(1.1.6) Judgment method between organic resin particle part and other resin part Whether the measuring part is the organic resin particle part or the other resin part, after the indentation test at the time of measuring the outermost layer hardness described later, the indented part is AFM. It can be determined by observing the surface with (atomic force microscope), SEM (scanning electron microscope), or the like.
When it is difficult to determine whether the measuring portion is an organic resin particle portion or another resin portion, a coating layer excluding the organic resin particles may be prepared and the hardness of the layer may be measured at the time of measuring the hardness of the outermost layer.

(1.2) Outermost layer hardness The hardness of the outermost layer (universal hardness) according to the present invention can be controlled by the amount of a polymerizable monomer, an inorganic filler, an antioxidant, etc., which will be described later.

The fact that the 10% displacement hardness of the organic resin particles is in ^{the range of 45 to 80 N / mm 2} and the outermost layer hardness is in ^{the range of 150 to 300 N / mm 2} suppresses image flow during image printing. However, it is preferable from the viewpoint of achieving a long life of the photoconductor.

Further, the outermost layer hardness is more preferably in the range of 170~270N / mm ^2, and even more preferably within the range of 180~250N / mm ^2.
Since the outermost surface hardness is within the above range with respect to the organic resin particles, the amount of wear can be kept within an appropriate range, and image flow can be suppressed.

The outermost surface hardness according to the present invention can be measured by an indentation test, nanointention, or the like.
For example, when a load F is applied to a Vickers indenter of a diamond quadrangular pyramid under a test load by a "Fisherscope HM2000" to push the surface of the first or second charge transport layer, the pushing depth h and the load F are as follows. A) can be obtained as universal hardness (HU [N / mm ^2]).

The measurement conditions are Vickers indenter (square pyramid indenter, angle 136 °), indentation speed 0.4 mN / sec, indentation load 2 mN, holding time 5 seconds, measurement environment 20 ° C., 50% RH.
Formula (A): HU (universal hardness) = F / (26.45 × h ² )

(1.2.1) Polymerizable Monomer The polymerizable monomer according to the present invention has a polymerizable group and is exposed to active rays such as ultraviolet rays, visible rays and electron beams, or by addition of energy such as heating. It is a compound that is polymerized (cured) to become a resin that is generally used as a binder resin for a photoconductor.

The polymerizable monomer is preferably a radically polymerizable monomer that is cured through a radical polymerization reaction.

Examples of the polymerizable monomer include a styrene-based monomer, an acrylic-based monomer, a methacrylic-based monomer, a vinyltoluene-based monomer, a vinyl acetate-based monomer, an N-vinylpyrrolidone-based monomer, and the like.

Examples of the binder resin include polystyrene, polyacrylate and the like.

The polymerizable group of the polymerizable monomer preferably has a carbon-carbon double bond and is polymerizable.

Since the polymerizable group can be cured with a small amount of light or in a short time, it may be an acryloyloxy group (CH ₂ = CHCOO−) or a methacryloyloxy group (CH ₂ = C (CH ₃ ) COO−). Especially preferable.

The polymerizable monomer can be synthesized by a known method, and can also be obtained as a commercially available product.

(1.2.2) Radical trapping agent As the radical trapping agent, a known compound can be used, for example, a phenol-based compound (preferably a hindered phenol-based compound), a hindered amine-based compound, a diphenylamine-based compound, or phosphorus. Examples thereof include atom-containing compounds (preferably phosphite-based compounds) and sulfur atom-containing compounds.

The functional group having a radical trapping ability is intended to be a radical trapping group in the above-mentioned radical trapping agent, and is, for example, a phenolic hydroxyl group or a nitrogen atom-containing group (for example, a nitrosamine group or a nitrogen atom-containing heterocyclic group (for example, a nitrosamine group or a nitrogen atom-containing heterocyclic group). Example: 2,2,6,6-tetramethyl-4-piperidyl group)), a phosphorus atom-containing group (for example, a phosphite group (group represented by P- (O− *) 3)), and sulfur. Examples thereof include an atom-containing group (for example, a sulfide group and a sulfur atom-containing heterocyclic group).

The nitrogen atom-containing heterocyclic group is a cyclic group containing a nitrogen atom, and may be aromatic or non-aromatic. The nitrogen atom-containing heterocyclic group may contain a heteroatom other than the nitrogen atom. The sulfur atom-containing heterocyclic group is a cyclic group containing a sulfur atom, and may be aromatic or non-aromatic. The sulfur atom-containing heterocyclic group may contain a heteroatom other than the sulfur atom.

Examples of the phenolic compound include 2,2'-methylenebis (4-methyl-6-t-butylphenol), 2,2'-methylenebis (4-ethyl-6-t-butylphenol), and 4,4'-thiobis. (3-Methyl-6-t-butylphenol) and 4,4'-butylidenebis (3-methyl-6-t-butylphenol) can be mentioned.

Examples of hindered amine compounds include 1,2,2,6,6, -pentamethylpiperidinyl methacrylate, 2,2,6,6, -tetramethylpiperidinyl methacrylate, and bis (2,2,6). 6-Tetramethyl-4-piperidin) sebacate can be mentioned.

Examples of the diphenylamine compound include diphenylamine, p, p'-dibutyldiphenylamine, and p, p'-di-tert-butyldiphenylamine.

Examples of the sulfur atom-containing compound include phenothiazine, dilauryl-3,3'-thiodipropionate, and dimyristyl-3,3'-thiodipropionate.

Examples of the phosphorus atom-containing compound include triphenylphosphine, diphenylisodecylphosphite, phenyldiisodecylphosphite, and tris (nonylphenyl) phosphite.

Commercially available products of radical scavengers include, for example, Sumilyzer GM (manufactured by Sumitomo Chemical Industries, Ltd.), Sumilyzer GS (manufactured by Sumitomo Chemical Industries, Ltd.), IRGAFOS 168 (BASF Japan Co., Ltd.), AO-412S (manufactured by Sumitomo Chemical Industries, Ltd.). ADEKA), Q-1301 (Fuji Film Wako Pure Chemical Industries, Ltd.).

(12.3) Inorganic filler The outermost layer of the present invention may contain an inorganic filler. When the inorganic filler is contained, the applicable inorganic filler is not particularly limited, and for example, magnesium oxide, lead oxide, aluminum oxide, zinc oxide, tin oxide, tantalum oxide, indium oxide, bismuth oxide, yttrium oxide, etc. Cobalt oxide, copper oxide, manganese oxide, selenium oxide, iron oxide, zirconium oxide, germanium oxide, titanium dioxide, niobium oxide, molybdenum oxide, vanadium oxide, copper-aluminum composite oxide and antimony-doped tin oxide can be mentioned. can. Among them, aluminum oxide (Al ₂ O ₃ ), tin oxide (SnO ₂ ), titanium dioxide (TiO ₂ ), and copper-aluminum composite oxide (CuAlO ₂ ) are preferable.

The above-mentioned inorganic filler may be used alone or in combination of two or more. Further, the inorganic filler may be a synthetic product or a commercially available product.

Further, the inorganic filler according to the present invention may be composite fine particles in which a conductive metal oxide is adhered to the surface of a core material made of an insulating material.

That is, the inorganic filler may be a composite fine particle having a core-shell structure having an outer shell (shell) made of the inorganic filler as described above on the surface of the core material (core) made of an insulating material.

(Composite particles with core-shell structure)
Examples of the material of the core material (core) constituting the composite particles having the core-shell structure include barium sulfate, aluminum oxide, and silica.

Preferred examples of the composite fine particles having a core-shell structure include composite particles having a core material made of barium sulfate and an outer shell made of tin oxide. The ratio of the number average primary particle diameter of the core material to the thickness of the outer shell may be appropriately set according to the type of the core material and the outer shell to be used and the combination thereof.

(Number of inorganic fillers, average primary particle size)
The number average primary particle size of the inorganic filler is preferably in the range of 10 to 200 nm. When the number average primary particle diameter of the inorganic filler is 10 nm or more, sufficient scratch resistance can be obtained.

On the other hand, when the number average primary particle diameter of the inorganic filler is 200 nm or less, when the inorganic filler is dispersed in the solvent at the time of forming the outermost layer, the inorganic filler does not settle in the dispersion liquid, and the photoconductor is stable. Can be manufactured.

Further, since the effect of improving the cleanability of the organic resin particles is exhibited when the organic resin particles come into contact with the toner, it is preferable that the number average primary particle diameter of the inorganic filler is smaller than that of the organic resin particles.

When the inorganic filler aggregates, it is preferable that the secondary particle size is smaller than that of the organic resin particles. When the inorganic filler aggregates, it is usually considered that two or three primary particles aggregate, so the maximum secondary particle size may be about 2.5 times the number average primary particle diameter.

For example, in the case of an inorganic filler having a number average primary particle diameter of 20 nm, the maximum secondary particle size may be about 50 nm.
The number average primary particle size of the inorganic filler is defined as the number average primary particle size measured by the following method.

First, a magnified photograph of 30,000 times a sample (inorganic filler, etc.) taken by a scanning electron microscope (manufactured by JEOL Ltd.) is taken.

Specifically, a magnified photograph of a sample (inorganic filler, etc.) taken at a magnification of 30,000 times with a scanning electron microscope (manufactured by JEOL Ltd.) is captured in a scanner.

Next, from the obtained photographic images, 300 inorganic filler images excluding the aggregated inorganic filler images were randomly selected from the automatic image processing analysis system Luzex AP Software Ver. Binarization is performed using 1.32 (manufactured by NIRECO CORPORATION) to calculate the horizontal ferret diameter of each of the inorganic filler images.

Then, the average value of each horizontal ferret diameter of the inorganic filler image is calculated and used as the number average primary particle diameter.

Here, the horizontal ferret diameter means the length of the side parallel to the x-axis of the circumscribed rectangle when the inorganic filler image is binarized.

Further, the measurement of the number average primary particle size of the inorganic filler shall be carried out for the inorganic filler containing no chemical species (coating layer) derived from the surface modifier.

Even if the surface modification treatment is applied to the inorganic filler, it is considered that the thickness is within the error range with respect to the inorganic filler (generally, the thickness is about 1/10000 with respect to the diameter of the inorganic filler). Therefore, the surface modification treatment is performed. It is assumed that there is no change in the average primary particle size by applying.

(Surface modifier of inorganic filler)
Further, the inorganic filler may be surface-modified with a surface-modifying agent. The surface modification treatment can be performed by subjecting the untreated inorganic filler as a raw material to the surface modification treatment with a surface modifier.

The inorganic filler surface-modified with the surface modifier is considered to be a surface coating filler containing a chemical species (coating layer) derived from the surface modifier and the inorganic filler. The surface-modified inorganic filler may have a chemical species (coating layer) derived from the surface modifier on at least a part of the surface thereof.

When the surface modification treatment of the inorganic filler is performed with the surface modifier, the inorganic filler is efficiently hydrophobized.

When a composition is prepared using the surface-modified inorganic filler and the two types of polymerizable monomers and the outermost layer of the photoconductor is formed from the polymerized cured product, the surface-modified inorganic filler is formed. Is advantageous for dispersibility because the compatibility with the polymerizable monomer is improved. Further, it is one of the preferable forms that the inorganic filler has a polymerizable group.

In the present invention, the surface modifier applied to the surface modification treatment of the inorganic filler is not particularly limited, and conventionally known ones can be used. Specific examples of the surface modifier include a silane coupling agent, a titanium coupling agent, a fluorine-based surface modifier, a surface modifier having a silicone chain, and the like.

The surface modifier can be used alone or in combination of two or more. Further, the surface modifier may be a synthetic product or a commercially available product. Specific examples of commercially available surface modifiers include the following compounds.

In the present invention, the polymerizable group has a carbon-carbon double bond and is a polymerizable group. The polymerizable group that the inorganic filler may have may be one kind or more, may be the same or different from each other, and may be a polymerizable group contained in the polymerizable monomer forming the polymerizable cured product. It may be the same as or different from.

The inorganic filler having a polymerizable group can be obtained, for example, by subjecting the inorganic filler to a surface modification treatment with a surface modifier consisting of a compound having a polymerizable group.

When an inorganic filler having a polymerizable group is used, the inorganic filler and the polymerizable monomer are polymerized, and it becomes easier to obtain mechanical strength, and the inorganic filler is less likely to fall off, so that the effect can be easily exerted for a long period of time.

(Shape of inorganic filler)
The shape of the inorganic filler is not particularly limited, and examples thereof include a spherical shape, an elliptical cross section, a needle shape, a disc shape, and an indefinite shape. From the viewpoint of dispersibility and the like, a spherical shape or an elliptical cross section is preferable.

(12.4) Antioxidant As the antioxidant, a known oxidizing agent can be used. For example, a phenol-based compound, a hydroquinone-based compound, a tocopherol-based compound, an amine-based compound, and the like can be mentioned. Among these, a hindered phenol derivative, a hindered amine derivative, or a mixture thereof is preferably used. Specific examples thereof include antioxidants described in JP-A-2000-305291.

2. 2. Photosensitive layer The photoconductor of the present invention has a photosensitive layer between the intermediate layer and the outermost layer. More specifically, the photosensitive layer is composed of a charge generation layer and a charge transport layer.

(2.1) Charge-generating layer The charge-generating layer in the photosensitive layer constituting the photoconductor contains a charge-generating substance and a binder resin (hereinafter, also referred to as “binder resin for charge-generating layer”). ..

Examples of the charge generating substance include azo raw materials such as Sudan Red and Diane Blue, quinone pigments such as pyrenequinone and anthanthronine, quinosianin pigments, perylene pigments, indigo pigments such as indigo and thioindigo, and a large number of pyranthron and diphthaloylpyrene. Examples thereof include, but are not limited to, ring quinone pigments and phthalocyanine pigments. Among these, polycyclic quinone pigments and titanylphthalocyanine pigments are preferable. These charge generating substances may be used alone or in combination of two or more.

As the binder resin for the charge generation layer, known resins can be used, for example, polystyrene resin, polyethylene resin, polypropylene resin, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, polyvinyl butyral resin, epoxy resin, etc. Polypolymer resin containing polyurethane resin, phenol resin, polyester resin, alkyd resin, polycarbonate resin, silicone resin, melamine resin, and two or more of these resins (for example, vinyl chloride-vinyl acetate copolymer resin, chloride). Vinyl-vinyl acetate-maleic anhydride copolymer resin), poly-vinylcarbazole resin and the like, but are not limited thereto. Among these, polyvinyl butyral resin is preferable. These binder resins for the charge generation layer may be used alone or in combination of two or more.

The content ratio of the charge generating substance in the charge generating layer is preferably in the range of 1 to 600 parts by mass, more preferably in the range of 50 to 500 parts by mass with respect to 100 parts by mass of the binder resin for the charge generating layer. Is.

The layer thickness of the charge generating layer varies depending on the characteristics of the charge generating substance, the characteristics of the binder resin for the charge generating layer, the content ratio, etc., but is preferably in the range of about 0.01 to 5 μm, more preferably 0. It is in the range of 05 to 3 μm.

(2.2) Charge Transport Layer The charge transport layer in the photosensitive layer constituting the photoconductor contains a charge transport substance and a binder resin (hereinafter, also referred to as “binder resin for charge transport layer”). ..

(2.2.1) Charge Transport Material The composition for forming the outermost layer according to the present invention may further contain a charge transport material.
The charge transporting substance is not particularly limited, and known substances can be used.
Examples thereof include carbazole derivatives, oxazole derivatives, oxaziazole derivatives, thiazole derivatives, thiadiazol derivatives, triazole derivatives, imidazole derivatives, imidazolone derivatives, imidazolidine derivatives, bisimidazolidine derivatives, styryl compounds, hydrazone compounds, pyrazoline compounds, oxazolones. Examples thereof include derivatives, benzimidazole derivatives, quinazoline derivatives, benzofuran derivatives, aclysine derivatives, phenazine derivatives, aminostilben derivatives, triarylamine derivatives, phenylenediamine derivatives, stillben derivatives, benzidine derivatives and the like.
Among these, triarylamine derivatives are preferable. The triarylamine derivative is preferably represented by the following general formula (1).

[In the above general formula (1), R ₁ , R ₂ , R ₃ and R ₄ independently represent an alkyl group having 1 to 7 carbon atoms or an alkoxy group having 1 to 7 carbon atoms. k, l and n each independently represent an integer of 0 to 5, and m represents an integer of 0 to 4. However, when k, l, n or m is 2 or more, a plurality of R ₁ , R ₂ , R ₃ and R ₄ existing may be the same or different from each other. .. Among these, it is preferable that R ₁ , R ₂ , R ₃ and R ₄ are independently alkyl groups having 1 to 3 carbon atoms. Further, k, l, n and m are preferably integers of 0 to 1 independently of each other. ]

As the compound represented by the general formula (1), for example, the compound described in JP-A-2015-114454 can be used.
Further, it can be synthesized by a known synthesis method, for example, the method disclosed in Japanese Patent Application Laid-Open No. 2006-143720.

(2.2.2) Non-reactive charge transporting substance It is preferable that the outermost layer contains a non-reactive charge transporting substance.
In the present invention, the non-reactive charge transporting substance means a substance that does not react with the reactive organic group of the polymerizable compound or the metal oxide fine particles when forming the outermost layer.

This non-reactive charge transport material has a charge transport property of transporting charge carriers in the outermost layer, does not show absorption in a short wavelength region, and has a molecular weight of 450 or less (preferably 320 to 420). (Within the range of), it is possible to enter the voids of the cured resin on the outermost layer. Therefore, it is possible to smoothly inject charge carriers from the charge transport layer without deteriorating the wear resistance of the outermost layer, and it is possible to transport charges to the surface of the outermost layer.

Examples of the non-reactive charge transporting substance include compounds represented by the above general formula (1).

The compound represented by the general formula (1) can be synthesized by a known synthesis method, for example, a method disclosed in JP-A-2006-143720.

(2.2.3) Binder Resin for Charge Transport Layer As the binder resin for the charge transport layer, a known resin can be used, and a polycarbonate resin, a polyacrylate resin, a polyester resin, a polystyrene resin, and a styrene-acrylic nitrile copolymer can be used. Examples thereof include a resin, a polymethacrylic acid ester resin, and a styrene-methacrylic acid ester copolymer resin, but a polycarbonate resin is preferable. Further, BPA (bisphenol A) type, BPZ (bisphenol Z) type, dimethyl BPA type, BPA-dimethyl BPA copolymer type polycarbonate resin and the like are preferable in terms of crack resistance, abrasion resistance and charging characteristics. These binder resins for the charge transport layer may be used alone or in combination of two or more.

The content ratio of the charge transporting substance in the charge transport layer is preferably in the range of 10 to 500 parts by mass, more preferably in the range of 20 to 250 parts by mass with respect to 100 parts by mass of the binder resin for the charge transport layer. Is.

The layer thickness of the charge transport layer varies depending on the characteristics of the charge transport material, the characteristics of the binder resin for the charge transport layer, the content ratio, and the like, but is preferably in the range of 5 to 40 μm, and more preferably in the range of 10 to 30 μm. Within.

Antioxidants, electron conductive agents, stabilizers, silicone oils and the like may be added to the charge transport layer. It is preferable that the antioxidant is disclosed in JP-A-2000-305291, and the electron conductive agent is disclosed in JP-A-50-137543, JP-A-58-76483, and the like.

3. 3. Conductive support The conductive support constituting the photoconductor of the present invention is not particularly limited as long as it has conductivity, and for example, a metal such as aluminum, copper, chromium, nickel, zinc, or stainless steel is drummed or used. Sheet-shaped, metal foil such as aluminum and copper laminated on plastic film, aluminum, indium oxide, tin oxide deposited on plastic film, conductive substance applied alone or with binder resin Examples thereof include metal, plastic film and paper provided with a conductive layer.

4. Intermediate layer The photoconductor of the present invention may be provided with an intermediate layer having a barrier function and an adhesive function between the conductive support and the photosensitive layer. In consideration of various failure preventions, it is preferable to provide an intermediate layer.

Such an intermediate layer contains, for example, a binder resin (hereinafter, also referred to as "binder resin for an intermediate layer") and, if necessary, conductive particles or metal oxide particles.

The binder resin for the intermediate layer is not particularly limited, and examples thereof include casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, polyamide resin, polyurethane resin, and gelatin. Of these, alcohol-soluble polyamide resins are preferred. These binder resins for the intermediate layer may be used alone or in combination of two or more.

The intermediate layer may contain various conductive particles and metal oxide particles for the purpose of adjusting resistance. For example, various metal oxide particles such as alumina, zinc oxide, titanium oxide, tin oxide, antimony oxide, indium oxide, and bismuth oxide can be used. Further, conductive particles (ultrafine particles) such as tin-doped indium oxide, antimony-doped tin oxide, and zirconium oxide can be used.

The number average primary particle diameter of such conductive particles or metal oxide particles is preferably 0.3 μm or less, and more preferably 0.1 μm or less.

These conductive particles or metal oxide particles may be used alone or in combination of two or more. When two or more kinds are mixed, it may take the form of a solid solution or a fusion.

The content ratio of the conductive particles or the metal oxide particles is preferably in the range of 20 to 400 parts by mass, and more preferably in the range of 50 to 350 parts by mass with respect to 100 parts by mass of the binder resin.

The layer thickness of the intermediate layer is preferably in the range of 0.1 to 15 μm, more preferably in the range of 0.3 to 10 μm.

[Manufacturing method of electrophotographic photosensitive member]
The method for producing the photoconductor of the present invention includes a step of forming an uncured film containing a polymerizable compound on a photosensitive layer on a conductive support and a step of irradiating the uncured film with light to obtain a cured resin. It is preferable that the product is produced by a production method having the following process, which is provided with a step of forming the outermost surface layer to be contained, and is not particularly limited.

Step (1): A step of forming an intermediate layer by applying a coating liquid for forming an intermediate layer to the outer peripheral surface of the conductive support and drying the coating liquid.
Step (2): A coating liquid for forming a charge generating layer is applied to the outer peripheral surface of the conductive support or the outer peripheral surface of the intermediate layer formed on the conductive support by the step (1) and dried. By forming a charge generation layer,
Step (3): A charge transport layer is formed by applying a coating liquid for forming a charge transport layer to the outer peripheral surface of the conductive support or the outer peripheral surface of the charge generation layer formed on the intermediate layer and drying the coating liquid. Process,
Step (4): A step of forming the outermost layer by applying a coating liquid for forming the outermost layer to the outer peripheral surface of the charge transport layer formed on the charge generation layer, polymerizing and curing the coating liquid.

The concentration of each component in the coating liquid for forming each layer is appropriately selected according to the layer thickness and production rate of each layer.

In the coating liquid for forming each layer, an ultrasonic disperser, a ball mill, a sand mill, a homomixer, or the like can be used as a means for dispersing particles such as conductive particles and metal oxide particles and a charge generating substance. However, it is not limited to these.

The method of applying the coating liquid for forming each layer is not particularly limited, and is, for example, a dip coating method, a spray coating method, a spinner coating method, a bead coating method, a blade coating method, a beam coating method, a slide hopper method, or a circular shape. Known methods such as the slide hopper method can be mentioned.

The method for drying the coating film can be appropriately selected depending on the type of solvent and the layer thickness, but heat drying or natural drying is preferable.

Hereinafter, the details of the forming process of each layer will be described.

<Step (1): Formation of intermediate layer>
For the intermediate layer, a binder resin for the intermediate layer is dissolved in a solvent to prepare a coating liquid for forming the intermediate layer, and if necessary, other components such as conductive particles, metal oxide particles, dispersants and leveling agents are prepared. Can be formed by applying the coating liquid on the conductive support to a certain layer thickness to form a coating film, and drying the coating film.

The coating liquid for forming the intermediate layer is preferably applied by using a dip coating method.

As the solvent used in the intermediate layer forming step, a solvent that satisfactorily disperses conductive particles and metal oxide particles and dissolves a binder resin for the intermediate layer, particularly a polyamide resin, is preferable. Specifically, alcohols having 1 to 4 carbon atoms such as methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol, tert-butanol, and sec-butanol (2-butanol) are soluble in the polyamide resin. It has excellent coating performance and is preferable. In addition, benzyl alcohol, toluene, dichloromethane, cyclohexanone, tetrahydrofuran and the like can be mentioned as an auxiliary solvent that can be used in combination with the above-mentioned solvent in order to improve the storage stability and the dispersibility of the particles and obtain a preferable effect.

<Step (2): Formation of charge generation layer>
For the charge generation layer, a charge generation substance is dispersed in a solution in which a binder resin for a charge generation layer is dissolved in a solvent to prepare a coating liquid for forming a charge generation layer, and the coating liquid is constant on the intermediate layer. It can be formed by applying to the layer thickness of the above to form a coating film and drying the coating film.

The coating liquid for forming the charge generation layer is preferably applied by using a dip coating method.

Examples of the solvent used for forming the charge generation layer include toluene, xylene, dichloromethane, 1,2-dichloroethane, methyl ethyl ketone, cyclohexane, ethyl acetate, tert-butyl acetate, methanol, ethanol, n-propyl alcohol, isopropyl alcohol, and the like. n-butanol, tert-butanol, sec-butanol (2-butanol), methyl cellosolve, 4-methoxy-4-methyl-2-pentanone, ethyl cellosolve, methanol, 1-dioxane, 1,3-dioxolane, pyridine, diethylamine However, it is not limited to these.

<Step (3): Formation of charge transport layer>
For the charge transport layer, a coating liquid for forming a charge transport layer in which a binder resin for the charge transport layer and a charge transport substance are dissolved in a solvent is prepared, and the coating liquid is applied onto the charge generation layer to a certain layer thickness. It can be formed by forming a coating film and drying the coating film.

The coating liquid for forming the charge transport layer is preferably applied by using a dip coating method.

Solvents used to form the charge transport layer include, for example, toluene, xylene, dichloromethane, 1,2-dichloroethane, methyl ethyl ketone, cyclohexanone, ethyl acetate, butyl acetate, methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-. Examples include, but are not limited to, butanol, tert-butanol, sec-butanol (2-butanol), tetrahydrofuran, 1,4-dioxane, 1,3-dioxolane, pyridine, diethylamine and the like.

<Step (4): Formation of outermost layer>
The outermost layer is a polymerizable monomer, organic resin particles, an inorganic filler treated with a surface modifier, and if necessary, other components such as a polymerization initiator, a specific radical scavenger, a lubricant, and a charge transporting substance. Is added to a known solvent to prepare a coating liquid for forming the outermost layer, and this coating liquid for forming the outermost layer is applied to the outer peripheral surface of the charge transport layer formed in the step (3) to form a coating film. By drying this coating film and irradiating it with active rays such as ultraviolet rays or electron beams, the polymerizable compound component in the coating film is polymerized and cured to form the outermost layer.

The coating liquid for forming the outermost layer is preferably applied by the slide hopper method using a circular slide hopper coating apparatus, and can be applied by a method disclosed in, for example, Japanese Patent Application Laid-Open No. 2015-114454.

As the solvent used for forming the outermost layer, any solvent can be used as long as it can dissolve or disperse a polymerizable compound, metal oxide particles, etc., for example, methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n. -Butanol, tert-butanol, sec-butanol (2-butanol), benzyl alcohol, toluene, xylene, dichloromethane, methyl ethyl ketone, cyclohexane, ethyl acetate, butyl acetate, methyl cellosolve, ethyl cellosolve, tetrahydrofuran, 1-dioxane, 1,3 − Dioxolane, pyridine, diethylamine and the like, but are not limited thereto.

The method for reacting the polymerizable compound is not particularly limited, and examples thereof include a method of reacting by electron beam cleavage, a method of adding a radical polymerization initiator, and a method of reacting with light and heat.

The cured resin component is produced by irradiating the coating film with active rays as a curing treatment, generating radicals to polymerize, and forming cross-linking bonds between and within the molecules by a cross-linking reaction to cure. Ultraviolet rays and electron beams are more preferable as the active rays, and ultraviolet rays are particularly preferable because they are easy to use.

As the ultraviolet light source, any light source that generates ultraviolet rays can be used without limitation. For example, a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a carbon arc lamp, a metal halide lamp, a xenon lamp, a flash (pulse) xenon, or the like can be used.

The irradiation conditions differ depending on each lamp, but the irradiation amount of the active ray is preferably in ^{the range of 5 to 500 mJ / cm 2} , and more preferably in the range of 5 to 100 mJ / cm ² .

The power of the lamp is preferably in the range of 0.1 to 5 kW, more preferably in the range of 0.5 to 4 kW, and even more preferably in the range of 0.5 to 3 kW.

The irradiation time for obtaining the required irradiation amount of the active ray is preferably 0.1 seconds to 10 minutes, and more preferably 0.1 seconds to 5 minutes from the viewpoint of work efficiency.

In the step of forming the outermost layer, drying can be performed before and after irradiation with the active rays and during irradiation with the active rays, and the timing of drying can be appropriately selected by combining these.

(Curing device and conditions for the outermost layer)
In the present invention, the surface hardness of the photoconductor in the long axis direction can be adjusted depending on the light irradiation conditions after coating the outermost layer.

The reason why the surface hardness of the photoconductor can be changed by the light irradiation device is that the surface hardness correlates with the integrated irradiation light amount of the light irradiating the photoconductor, and the integrated irradiation light amount is (integrated irradiation light amount) = (photoreceptor drum). Since it is determined by (irradiation light amount per unit area) × (irradiation time per unit area), the surface hardness of the photoconductor can be changed by changing (i) the irradiation light amount or (ii) the irradiation time. ..

As an example, when the light irradiation device described in Japanese Patent Application Laid-Open No. 2013-57787 is used, (i) the irradiation intensity of light is changed or changed at an arbitrary position when the photoconductor work is pulled up from below. (Ii) By changing the pulling speed of the work, that is, changing the irradiation time, the integrated irradiation light amount of the photoconductor drum surface can be changed in the long axis direction of the photoconductor, and the surface hardness of the photoconductor can be changed. .. In particular, the means for changing the work pulling speed of (ii) is preferable from the viewpoint of controllability.

<Electrophotograph image formation method>
The method for forming an electrophotographic image according to the present invention is at least
1) The charging process for charging the surface of the electrophotographic photosensitive member,
2) An exposure step of forming an electrostatic latent image by exposing the surface of the electrophotographic photosensitive member.
3) A developing process in which the electrostatic latent image is visualized with toner to form a toner image.
4) A transfer step of transferring the toner image to a transfer medium,
It is preferable that the electrophotographic photosensitive member used in 1) to 4) is the electrophotographic photosensitive member of the present invention.

Also, if necessary, 5) a cleaning process to remove residual toner,
6) It may have a static elimination step of removing the residual charge.

The electrophotographic photosensitive member of the present invention (hereinafter, also simply referred to as a photoconductor) can be used in various known image forming methods of the electrophotographic method. For example, it can be used for a monochrome image forming method or a full-color image forming method. In the full-color image forming method, a four-cycle image forming method composed of four types of color developing devices for each of yellow, magenta, cyan, and black and one photoconductor, and color developing for each color. Any image forming method can be used, such as a tandem image forming method in which an image forming unit having an apparatus and a photoconductor is mounted for each color.

As a method for forming an electrophotographic image according to the present invention, specifically, using the photoconductor of the present invention, the photoconductor is charged (charging step) by a charging device and image-exposed (exposure step). The electrostatic latent image formed by the above is developed (development step) using a developing device to visualize it to obtain a toner image. This toner image is transferred (transfer step) onto a transfer medium such as copy paper or a transfer belt, and then a static elimination step is performed, and then the next image formation cycle is performed. The toner image transferred on a transfer medium such as a transfer belt is transferred onto the copy paper, and the toner image transferred onto the copy paper is fixed (fixed step) on the copy paper by a fixing process such as a contact heating method. To obtain a visible image. After the transfer step, the toner remaining on the photoconductor (transfer residual toner) is removed (cleaning step) by a rubber blade or the like. This cleaning step may be performed before or after the static elimination step, but when the static elimination step is static elimination by light irradiation, the toner remaining on the photoconductor absorbs the static elimination light after the cleaning step. It is preferable because it does not interfere with it and can effectively eliminate static electricity.

In the static elimination process, either AC static elimination (AC static elimination) or optical static elimination may be used, but AC static elimination requires the installation of an AC power supply, which causes problems such as space problems or large-scale equipment. Static elimination is preferable.

<Electrophotograph image forming apparatus>
Next, a specific electrophotographic image forming method will be described using an electrophotographic image forming apparatus.

In the present invention, the electrophotographic image forming apparatus uses the photoconductor of the present invention to form a charging means charged by the charging device on the photoconductor, and an electrostatic latent image formed by image exposure. It has means, a developing means for obtaining a toner image by visualizing it by developing it using a developing device, a transfer means for transferring the toner image onto a transfer medium such as paper or a transfer belt, and a static elimination means. .. The toner image directly transferred onto the copy paper and the toner image transferred onto the paper via a transfer medium such as a transfer belt obtain a visible image by a fixing means fixed to the copy paper by a fixing process such as a contact heating method. After the transfer, the toner remaining on the photoconductor (transfer residual toner) is removed by a cleaning means such as a cleaning blade.

FIG. 2 is a schematic cross-sectional view showing the structure of a tandem type electrophotographic image forming apparatus including the electrophotographic photosensitive member of the present invention.

The image forming apparatus 100 shown in FIG. 2 is referred to as a tandem type color image forming apparatus, and is supplied with four sets of image forming units (image forming units) 10Y, 10M, 10C, 10Bk, an intermediate transfer body unit 7. It is composed of a paper means 21 and a fixing means 24. A document image reading device SC is arranged above the main body A of the electrophotographic image forming device.

The four image forming units 10Y, 10M, 10C, and 10Bk rotate around the photoconductors 1Y, 1M, 1C, and 1Bk with the charging means 2Y, 2M, 2C, and 2Bk, and the exposure means 3Y, 3M, 3C, and 3Bk. From the cleaning means 6Y, 6M, 6C, 6Bk for cleaning the developing means 4Y, 4M, 4C, 4Bk, the primary transfer rollers 5Y, 5M, 5C, 5Bk as the primary transfer means, and the photoconductors 1Y, 1M, 1C, 1Bk. It is configured.

In the electrophotographic image forming apparatus of the present invention, the photoconductors of the present invention described above are used as the photoconductors 1Y, 1M, 1C, and 1Bk, respectively.

The image forming units 10Y, 10M, 10C, and 10Bk have the same configuration except that the toner colors provided are different, such as yellow (Y) color, magenta (M) color, cyan (C) color, and black (Bk) color, respectively. Is. Therefore, in the following, the image forming unit 10Y will be described in detail as an example.

The image forming unit 10Y has a charging means 2Y, an exposure means 3Y, a developing means 4Y, and a cleaning means 6Y around the photoconductor 1Y which is an image forming body, and a yellow (Y) toner image is formed on the photoconductor 1Y. It is what forms.

The charging means 2Y is a means for uniformly charging the surface of the photoconductor 1Y to a negative electrode property. As the charging means 2Y, for example, a corona discharge type charger is used.

The exposure means 3Y is a means for forming an electrostatic latent image corresponding to a yellow image by exposing the photoconductor 1Y to which a uniform potential is applied by the charging means 2Y based on an image signal (yellow). be. As the exposure means 3Y, one composed of LEDs and imaging elements in which light emitting elements are arranged in an array in the axial direction of the photoconductor 1Y, a laser optical system, or the like is used.

The developing means 4Y is, for example, a voltage applying device that applies a DC and / or AC bias voltage between a developing sleeve (not shown) and a photoconductor that has a built-in magnet and holds a developer and rotates, and the developing sleeve. It consists of.

The developing means 4Y comprises, for example, a developing sleeve having a built-in magnet and holding a developing agent and rotating, and a voltage applying device for applying a DC and / or AC bias voltage between the developing sleeve and the photoconductor. ..

The fixing means 24 is, for example, a heat roller fixing composed of a heating roller provided with a heating source inside and a pressure roller provided in a state of being pressure-contacted so as to form a fixing nip portion on the heating roller. The method is mentioned.

The cleaning means 6Y is composed of a cleaning blade. A brush roller may be provided on the upstream side of the cleaning blade.
Further, a lubricant supply means (not shown) for supplying (applying) the lubricant to the surface of the photoconductor 1Y may be provided. The lubricant supply means can be provided, for example, on the downstream side of the primary transfer roller 5Y and on the upstream side of the cleaning means 6Y. However, it may be on the downstream side of the cleaning means 6Y.

The image forming apparatus 100 is configured by integrally coupling a photoconductor and components such as a developing means and a cleaning means as a process cartridge (image forming unit), and the image forming unit can be detachably attached to and detached from the apparatus main body. It may be configured. Further, at least one of a charging means, an exposure means, a developing means, a transfer means, and a cleaning means is integrally supported together with a photoconductor to form a process cartridge (image forming unit), and a detachable single image is formed on the main body of the apparatus. The unit may be a detachable configuration using a guide means such as a rail of the main body of the device.

The endless belt-shaped intermediate transfer unit 7 has an endless belt-shaped intermediate transfer body 70 as a semi-conductive endless belt-shaped second image carrier that is wound by a plurality of rollers and rotatably supported.

Images of each color formed by the image forming units 10Y, 10M, 10C and 10Bk are sequentially transferred onto the rotating endless belt-shaped intermediate transfer body 70 by the primary transfer rollers 5Y, 5M, 5C and 5Bk as the primary transfer means. Then, a composite color image is formed. The transfer material (image support for supporting the fixed final image: plain paper, transparent sheet, etc.) P housed in the paper feed cassette 20 is fed by the paper feed means 21, and the plurality of intermediate rollers 22A, It is conveyed to a secondary transfer roller 5b as a secondary transfer means via 22B, 22C, 22D, and a resist roller 23, and is secondarily transferred onto a transfer material P to collectively transfer a color image. The transfer material P to which the color image is transferred is fixed by the fixing means 24, sandwiched between the paper ejection rollers 25, and placed on the paper ejection tray 26 outside the machine. Here, the transfer support of the toner image formed on the photoconductor such as the intermediate transfer body or the transfer material is collectively referred to as a transfer medium.

On the other hand, after the color image is transferred to the transfer material P by the secondary transfer roller 5b as the secondary transfer means, the residual toner is removed from the endless belt-shaped intermediate transfer body 70 in which the transfer material P is subjected to curvature separation by the cleaning means 6b. Toner.

During the image forming process, the primary transfer roller 5Bk is always in contact with the photoconductor 1Bk. The other primary transfer rollers 5Y, 5M and 5C abut on the corresponding photoconductors 1Y, 1M and 1C, respectively, only during color image formation.

The secondary transfer roller 5b comes into contact with the endless belt-shaped intermediate transfer body 70 only when the transfer material P passes through the transfer material P and the secondary transfer is performed.

Further, the housing 8 can be pulled out from the device main body A via the support rails 82L and 82R.

The housing 8 includes image forming portions 10Y, 10M, 10C and 10Bk, and an endless belt-shaped intermediate transfer unit 7.

The image forming portions 10Y, 10M, 10C and 10Bk are arranged in parallel in the vertical direction. An endless belt-shaped intermediate transfer unit 7 is arranged on the left side of the photoconductors 1Y, 1M, 1C, and 1Bk. The endless belt-shaped intermediate transfer unit 7 includes an endless belt-shaped intermediate transfer body 70 that can be rotated by winding rollers 71, 72, 73, and 74, a primary transfer roller 5Y, 5M, 5C, and 5Bk, and a cleaning means 6b. Consists of.

<Toner and developer>
In the present invention, the "toner matrix particle" constitutes the matrix of the "toner particle". The "toner matrix particles" contain at least a binder resin and a colorant, and may also contain other constituents such as a mold release agent (wax) and a charge control agent, if necessary. "Toner matrix particles" are referred to as "toner particles" due to the addition of an external additive. The "toner" means an aggregate of "toner particles".

In the present invention, the toner applied to the image forming apparatus is not particularly limited, and various known toners can be used.

As the toner, either a pulverized toner or a polymerized toner can be used, but it is preferable to use the polymerized toner from the viewpoint of obtaining a high-quality image.

The average particle size of the toner is not particularly limited, but is preferably in the range of 2 to 8 μm in terms of volume-based median diameter. By setting this range, the resolution can be further increased.

Further, an appropriate amount of inorganic particles such as silica and titania having an average particle size of about 10 to 300 nm, an abrasive having an average particle size of about 0.2 to 3 μm, etc. are externally added to the toner matrix particles as an external additive. be able to.

When the toner is used as a two-component developer, the carrier is a conventionally known material such as a ferromagnetic metal such as iron, a ferromagnetic metal and an alloy such as aluminum and lead, and a compound of a ferromagnetic metal such as ferrite and magnetite. Magnetic particles composed of can be used. Of these, ferrite is particularly preferable.

As the carrier, it is preferable to use a carrier coated with a resin or a so-called resin-dispersed carrier in which magnetic particles are dispersed in the resin. The resin composition for coating is not particularly limited, but for example, it is preferable to use a cyclohexyl methacrylate-methyl methacrylate copolymer or the like.

The volume-based median diameter of the carrier is preferably in the range of 15 to 100 μm, more preferably in the range of 25 to 60 μm.

The concentration of the toner contained in the two-component developer is preferably in the range of 4.0 to 8.0% by mass.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In the following examples, the operation was performed at room temperature (25 ° C.) unless otherwise specified. Unless otherwise specified, "%" and "part" mean "% by mass" and "part by mass", respectively.

[Preparation of organic resin particles 1 to 5]
Organic resin particles 1 to 5 were prepared as shown below.
Table I shows the resin composition and the charging ratio of the organic resin particles 1 to 5.
Here, the 10% displacement hardness of the organic resin particles 1 to 5 was measured using a microcompression tester MCT-510 (manufactured by Shimadzu Corporation).
The measurement results are shown in Table II, which will be described later.
As a test method, after a very small amount of organic resin particles were sprayed on a sample table, the diameters in the X and Y directions were measured, the average was taken as the particle diameter, and a compression test was performed one by one.
In the test, each resin particle was measured 5 times and evaluated by an average value. In addition, the state of the sample being compressed was also observed using the side observation kit.
The 10% displacement hardness corresponds to the test force at the time when the displacement amount reaches 10% of the particle diameter when the test force is applied to one particle at a load speed of 0.223 mN / sec in the compression test. Hardness.

[Preparation of organic resin particles 1]
In a 100 mL reaction flask equipped with a stirrer, a reflux condenser and a thermometer, 4.51 g of melamine, 1.53 g of acetoguanamine, 11.58 g of 37% formalin, 20 mass% aqueous silica sol [Nissan Chemical Industry Co., Ltd., Snow TEX (registered trademark) ST-N (trade name), average particle size 12 nm, pH 9.5] 0.93 g, 37.1 g of water, and 67.2 μL of 25% ammonia water were charged.
Then, the temperature of the mixture was raised while stirring, the temperature was maintained at 70 ° C., and the reaction was carried out for 30 minutes to prepare an aqueous solution of the initial condensate of the melamine resin.
Next, while maintaining the temperature at 70 ° C., 3.59 g of a 5% by mass aqueous solution of paratoluenesulfonic acid was added to the aqueous solution of the obtained initial condensate.
After about 5 minutes, the inside of the reaction system became cloudy and polycondensation polymer resin particles were precipitated.
Then, the temperature was raised to 90 ° C. and the curing reaction was continued for 3 hours.
After cooling, the obtained reaction solution was filtered and dried to obtain white cured resin particles.

[Preparation of organic resin particles 2]
In a 30 mL reaction flask equipped with a stirrer, a reflux condenser and a thermometer, 0.50 g of melamine, 0.52 g of guanamine, 1.93 g of 37% formalin, 20 mass% aqueous silica sol [Snowtex, manufactured by Nissan Chemical Industry Co., Ltd.] (Registered trademark) ST-N (trade name), average particle size 12 nm, pH 9.5] 0.17 g, water 6.17 g, and 25% ammonia water 20 μL were charged.
Then, the temperature of the mixture was raised while stirring, the temperature was maintained at 70 ° C., and the reaction was carried out for 30 minutes to prepare an aqueous solution of the initial condensate of the melamine resin.
Next, while maintaining the temperature at 70 ° C., 0.58 g of a 5% by mass aqueous solution of paratoluenesulfonic acid was added to the aqueous solution of the obtained initial condensate.
After about 2 minutes, the inside of the reaction system became cloudy and polycondensation polymer resin particles were precipitated.
Then, the temperature was raised to 90 ° C. and the curing reaction was continued for 3 hours.
After cooling, the obtained reaction solution was filtered and dried to obtain white cured resin particles.

[Preparation of organic resin particles 3]
In a 100 mL reaction flask equipped with a stirrer, a reflux condenser and a thermometer, 0.30 g of benzoguanamine, 0.30 g of acetoguanamine, 1.81 g of melamine, 4.13 g of 37% formalin, 20 mass% aqueous silica sol [Nissan Chemical Industry (Nissan Chemical Industry Co., Ltd.) Manufactured by Snowtex (registered trademark) ST-N (trade name), average particle size 12 nm, pH 9.5] 0.38 g, 39.7 g of water, and 0.024 g of 25% ammonia water were charged.
Then, the temperature of the mixture was raised to 80 ° C. with stirring, and the mixture was further stirred for 5 minutes to prepare an aqueous solution of the initial condensate of the melamine resin.
Next, while maintaining the temperature at 80 ° C., 1.41 g of a 5% by mass aqueous solution of paratoluenesulfonic acid was added to the aqueous solution of the obtained initial condensate.
After about 3 minutes, the inside of the reaction system became cloudy and polycondensation polymerized amino resin particles were precipitated.
Then, the temperature was raised to 90 ° C. and the curing reaction was continued for 3 hours.
After cooling, the obtained reaction solution was filtered and dried to obtain white cured resin particles.

[Preparation of organic resin particles 4]
In a 500 mL reaction flask equipped with a stirrer, a reflux condenser and a thermometer, 5.00 g of benzoguanamine, 6.50 g of 37% formalin, 20 mass% aqueous silica sol [Nissan Chemical Industry Co., Ltd., Snowtex (registered trademark) ST -N (trade name), average particle size 12 nm, pH 9.5] 0.78 g, 355.1 g of water, and 56 μL of 25% ammonia water were charged.
Then, the temperature of the mixture was raised to 95 ° C. with stirring to prepare an aqueous dispersion of the initial condensate of the benzoguanamine resin.
Next, while maintaining the temperature at 95 ° C., 2.92 g of a 5 mass% paratoluenesulfonic acid aqueous solution was added to the aqueous dispersion of the obtained initial condensate.
Immediately after the addition, the inside of the reaction system became cloudy and benzoguanamine resin particles were precipitated.
After that, the temperature was kept at 95 ° C., and the curing reaction was continued for 3 hours.
After cooling, the obtained reaction solution was filtered and dried to obtain white cured resin particles.

[Preparation of Organic Resin Particles 5]
CTU guanamine 0.50 g, acetoguanamine 4.50 g, 37% formalin 9.04 g, 20 mass% aqueous silica sol [manufactured by Nissan Chemical Industries, Ltd., in a 200 mL reaction flask equipped with a stirrer, a reflux condenser and a thermometer. Snowtex (registered trademark) ST-N (trade name), average particle size 12 nm, pH 9.5] 0.78 g, 65.6 g of water, and 56 μL of 25% ammonia water were charged.
Then, the temperature of the mixture was raised to 90 ° C. with stirring to prepare an aqueous solution of an initial condensate of acetguanamine resin.
Next, while maintaining the temperature at 90 ° C., 2.92 g of a 5% by mass aqueous solution of paratoluenesulfonic acid was added to the aqueous solution of the obtained initial condensate.
After about 10 minutes, the inside of the reaction system became cloudy and polycondensation polymer resin particles were precipitated.
Then, the curing reaction was continued for 3 hours at a temperature of 90 ° C.
After cooling, the obtained reaction solution was filtered and dried to obtain white cured resin particles.

<Preparation of organic resin particle dispersion PD- (1) to (5)>
[Preparation of organic resin particle dispersion PD- (1)]
The following components were dispersed for 120 minutes using an ultrasonic homogenizer (US-150AT, manufactured by Nissei Tokyo Office) with an amplitude set to 30 μm.

Organic resin particles 1: 150 parts by mass 2-butanol 850 parts by mass

[Preparation of Organic Resin Particle Dispersion Liquid PD- (2)-(5)]
In the preparation of the organic resin fine particle dispersion liquid PD- (1), the organic resin particle dispersion liquid PD- (2) to (5) are similarly changed except that the organic resin particles used are changed to the organic resin particles 2 to 5, respectively. ) Was prepared.

[Preparation of Conductive Fine Particles 1]
To 40 mL of methanol, 20 g of tin oxide (number average primary particle diameter: 20 nm) as a mother was added and dispersed for 120 minutes using an ultrasonic homogenizer.
Next, 1 g of 3-methacryloxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KBM503) and 40 mL of toluene were added as a reactive organic group-containing surface modifier having a polymerizable group, and the mixture was stirred at room temperature for 2 hours. did.
Next, after removing the solvent with an evaporator, the conductive fine particles 1 having a polymerizable group, which were surface-modified with a reactive organic group-containing surface modifier (KBM503), were obtained by heating at 120 ° C. for 1 hour. Made.

<Preparation of Conductive Fine Particle Dispersion Liquid FD-1>
The following components were dispersed for 120 minutes using an ultrasonic homogenizer (US-150AT, manufactured by Nissei Tokyo Office) with an amplitude set to 30 μm.

Conductive fine particles 1 200 parts by mass 2-butanol 800 parts by mass

[Preparation of Photoreceptor 1]
A. Preparation of Conductive Support The surface of the cylindrical aluminum support was machined to prepare the conductive support.

B. Formation of the intermediate layer The following components were mixed in the following amounts and dispersed in a batch system for 10 hours using a sand mill as a disperser to prepare a coating liquid for the intermediate layer.
The coating liquid was applied to the surface of the conductive support by a dip coating method and dried at 110 ° C. for 20 minutes to form an intermediate layer having a layer thickness of 2 μm on the conductive support.

In addition, X1010 (manufactured by Daicel Degussa) was used as the polyamide resin.
Further, SMT500SAS (manufactured by TAYCA) was used as the titanium oxide particles.
Polyamide resin 10 parts by mass Titanium oxide particles 11 parts by mass Ethanol 200 parts by mass

C. Formation of charge generation layer The following components are mixed in the following amounts, and using a circulating ultrasonic homogenizer (RUS-600TCVP; manufactured by Nissei Tokyo Office Co., Ltd.), the circulation flow rate is 40 L / hour at 19.5 kHz and 600 W. A coating liquid for forming a charge generation layer was prepared by dispersing over 5 hours.

The coating liquid was applied to the surface of the intermediate layer by a dip coating method and dried to form a charge generation layer having a layer thickness of 0.3 μm.

The charge generating substances described below include titanylphthalocyanine having clear peaks at 8.3 °, 24.7 °, 25.1 °, and 26.5 ° in Cu-Kα characteristic X-ray diffraction spectrum measurement and ( A mixed crystal of a 1: 1 adduct of 2R, 3R) -2,3-butanediol and unadded titanylphthalocyanine was used.

In addition, Eslek BL-1 (manufactured by Sekisui Chemical Co., Ltd., "Eslek" is a registered trademark of Sekisui Chemical Co., Ltd.) was used as the polyvinyl butyral resin.
In addition, 3-methyl-2-butanone / cyclohexanone = 4/1 (volume ratio) was used as the mixed solution.

Charge generator 24 parts by mass Polyvinyl butyral resin 12 parts by mass Mixture 400 parts by mass

D. Formation of charge transport layer A coating liquid for forming a charge transport layer, which is a mixture of the following components in the following amounts, is applied to the surface of the charge generation layer by a dip coating method and dried at 120 ° C. for 70 minutes to charge a layer with a thickness of 24 μm. A transport layer was formed on the charge generation layer.

As the polycarbonate resin, Iupylon Z300 (bisphenol Z-type polycarbonate manufactured by Mitsubishi Gas Chemical Company, Inc.) was used.
Further, IRGANOX1010 (manufactured by BASF, "IRGANOX" is a registered trademark of BASF) was used as an antioxidant.

Charge transport material represented by the following structural formula (2) 50 parts by mass Polycarbonate resin 100 parts by mass Antioxidant 5 parts by mass Crossbox / toluene (volume ratio 8/2) mixed solution 600 parts by mass Silicone oil "KF-96" ( Shin-Etsu Chemical Co., Ltd.) 0.05 parts by mass

E. Formation of the outermost layer Next, the outermost layer coating liquid mixed in the following amounts was dispersed for 5 hours using a sand mill as a disperser, and then 10 parts by mass of a polymerization initiator (trade name: Omnirad819 (manufactured by BASF)) was added to shield the light from light. The coating liquid for forming the outermost layer was prepared by stirring and dissolving underneath.

Monomer: Methacrylic monomer (trade name: SR350) 100 parts by mass Organic resin particles 1:10% Displacement hardness 75 (N / mm ² ) 5 parts by mass Charge transport material: 10 parts by mass of the following exemplified compound C-5

Antioxidant: (Product name: Sumilyzer GS) 5 parts by mass THF 100 parts by mass 2-butanol 400 parts by mass

This coating liquid for forming the outermost layer was applied to the surface of the charge transport layer using a circular slide hopper coating machine.
Next, the applied outermost layer coating film was irradiated with ultraviolet rays (main wavelength: 365 nm) for 1 minute using a metal halide lamp (ultraviolet illuminance: 16 mW / cm ² , integrated light intensity: 960 mJ / cm ² ), and the outermost layer coating film was applied. The outermost layer having a layer thickness of 5.0 μm was formed on the charge transport layer, and the photoconductor 1 was produced.

[Preparation of Photoreceptors 2-12 and 15-19]
As shown in Table II, the resin type, charge transport material, organic resin particles, and conductive fine particles are appropriately adjusted for the ratio of 10% displacement hardness / outermost layer hardness of the organic resin particles on the outermost layer and the amount of the antioxidant (smilizer GS). However, the photoconductors 2 to 12 and 15 to 19 were prepared in the same manner as the photoconductor 1 except that the preparations were made as shown in Table II.

[Preparation of Photoreceptor 13]
A protective layer coating solution in which the resin and the solvent were mixed in the following amounts was prepared by applying CSH (circular slide hopper coating machine) so that the layer thickness was 5 μm, and dried at 120 ° C. for 70 minutes by the same method as that of the photoconductor 1. The photoconductor 13 was produced.

Charge transport material represented by the structural formula (2) 50 parts by mass Polycarbonate resin 100 parts by mass Antioxidant 5 parts by mass Crossbox / toluene (volume ratio 8/2) mixed solution 1500 parts by mass Silicone oil "KF-96" ( Shin-Etsu Chemical Co., Ltd.) 0.15 parts by mass

[Preparation of Photoreceptor 14]
The photoconductor 14 was prepared by the same method as that of the photoconductor 13 except that the resin was changed as shown in Table II.

[Measurement of outermost surface hardness of photoconductors 1 to 19]
The height of the outermost layer of the photoconductors 1 to 19 was measured by the method described in the above-mentioned outermost layer hardness (1.1).

[Manufacturing of image forming apparatus for evaluation]
Using a full-color printing machine (bizhub PRESS C1070, manufactured by Konica Minolta KK), the photoconductor produced above was placed at the black (K) position of the image forming unit to produce an image forming apparatus for evaluation.

[An endurance test]
In the durability test, a test image consisting of a strip-shaped solid image with a coverage of 10% shown in FIG. 3 was continuously printed on 500,000 sheets in A4 horizontal feed under a 50% RH environment at 23 ° C.
After that, the following evaluation test was carried out.

[Cleaning property evaluation test]
Under the environment of 10 ° C. and 20% RH, a test image consisting of a horizontal band-shaped solid image with a coverage of 40% shown in FIG. 4 was continuously printed on 20,000 sheets in A4 horizontal feed.
The top and bottom printed parts (bands) of this image have 100% coverage in the direction perpendicular to the rotation axis direction (circumferential direction) of the photoconductor, and the two central printed parts (bands). The coverage of the part) is 50% in the direction perpendicular to the rotation axis direction (circumferential direction) of the photoconductor.
After that, the photoconductor was removed from the unit, and the contamination of the lubricant-applied brush was visually confirmed.

The lubricant-applied brushes after the above evaluation were ranked according to the following evaluation criteria.
Here, as evaluation ranks, ranks A to C are regarded as acceptable, and ranks D to E are regarded as rejected.

(Evaluation criteria)
A: The lubricant-applied brush is not contaminated and is good. (Pass)
B: White contamination is observed on the lubricant-applied brush only in the area corresponding to the image corresponding to 100% coverage in the circumferential direction, but there is no problem in practical use. (Pass)
C: In addition to the area corresponding to the image corresponding to 100% coverage in the circumferential direction, white contamination is observed in the lubricant-applied brush in the area corresponding to 50%, but there is no problem in practical use. (Pass)
D: The lubricant-applied brush is contaminated with toner only in the area corresponding to the image corresponding to 100% of the coverage in the circumferential direction, which is practically problematic. (failure)
E: In addition to the area corresponding to the image corresponding to the coverage of 100% in the circumferential direction, the lubricant-coated brush is contaminated with the toner in the area corresponding to 50%, which is practically problematic. (failure)

[Abrasion resistance evaluation test; Abrasion resistance evaluation]
The evaluation was made based on the amount of layer thickness wear on the outermost layer of the photoconductor before and after the durability test.
Specifically, the layer thickness of the outermost layer is measured at 10 random locations in the uniform layer thickness portion (excluding the layer thickness variation portion at the front end portion and the rear end portion of the coating by creating a layer thickness profile), and the average thereof. The value is taken as the layer thickness of the outermost layer.
As the layer thickness measuring instrument, an eddy current type layer thickness measuring instrument "EDDY560C" (manufactured by HELMUT FISCHER GMBTE CO) was used, and the difference in the layer thickness of the outermost layer before and after the durability test was calculated as the layer thickness depletion amount (μm).

The amount of wear of the photoconductor was ranked according to the following evaluation criteria.
Here, as an evaluation rank, if the layer thickness wear amount is less than 4 μm, it is evaluated as practical (pass).

(Evaluation criteria)
A Within 1 μm: No problem in practical use (passed)
B 1-2.5 μm: No problem in practical use (passed)
C 2.5-4 μm: No problem in practical use (passed)
D 4-5 μm: There is a practical problem (failure)
E 5 μm or more: There is a practical problem (failure)

<Test of image flow evaluation; Scratch resistance evaluation>
In a high temperature and high humidity environment (temperature 30 ° C, humidity 85% RH), turn off the power after printing 2000 character charts with a printing rate of 5% continuously, leave it for 8 hours, and then turn on the power to display an A3 halftone image. 20 sheets were printed in succession.

The image flow was ranked according to the following evaluation criteria.
Here, as an evaluation rank, the number of halftone images when they were restored to the level before being left unattended was evaluated.

(Evaluation criteria)
A: Recovered within the third piece. (Pass)
B: Recovered within the 7th sheet. (Pass)
C: Recovered within the 20th sheet. (Pass)
D: Recovered within the 40th sheet. (failure)
E: Recovered after the 50th sheet. (failure)

As shown in the evaluation results shown in Table II above, it can be seen that the examples are superior to the comparative examples.

1Y, 1M, 1C, 1Bk Photoconductor 2Y, 2M, 2C, 2Bk Charging means 3Y, 3M, 3C, 3Bk Exposure means 4Y, 4M, 4C, 4Bk Developing means 5Y, 5M, 5C, 5Bk Primary transfer roller 5b Secondary transfer Roller 6Y, 6M, 6C, 6Bk, 6b Cleaning means 7 Intermediate transfer unit 8 Housing 10Y, 10M, 10C, 10Bk Image forming unit 20 Paper cassette 21 Paper feed means 22A, 22B, 22C, 22D Intermediate roller 23 Resist roller 24 Fixing means 25 Paper ejection roller 26 Paper ejection tray 70 Intermediate transfer member 71, 72, 73, 74 Roller 77 Intermediate transfer element 82L, 82R Support rail 100 Image forming device A Main body SC Original image reading device P Transfer material 101A, 101B Electronic Photophotosensitive material 102 Conductive support 103 Intermediate layer 104 Photosensitive layer 105 Outermost layer 106 Charge generation layer 107 Charge transport layer

Claims (6)

An electrophotographic photosensitive member having a curable outermost surface layer on at least the photosensitive layer.
The outermost layer contains at least organic resin particles, and
An electrophotographic feature in which the ratio of the 10% displacement hardness of the organic resin particles to the outermost layer hardness (10% displacement hardness of the organic resin particles / outermost surface layer hardness) is in the range of 0.15 to 0.55. Photoreceptor. An electrophotographic photosensitive member having a 10% displacement hardness of the organic resin particles in ^{the range of 45 to 80 N / mm 2} and a surface hardness of the outermost layer in ^{the range of 150 to 300 N / mm 2.} The above-mentioned claim is characterized in that the outermost layer is a cured product formed of a composition containing at least a polymerizable monomer, conductive fine particles having a polymerizable group, and a charge transporting substance having a polymerizable group. 1 or the electrophotographic photosensitive member according to claim 2. The electrophotographic photosensitive member according to any one of claims 1 to 3, wherein the outermost surface hardness is adjusted by a radical scavenger. A method for forming an electrophotographic image, which comprises using the electrophotographic photosensitive member according to any one of claims 1 to 4. An electrophotographic image forming apparatus comprising the electrophotographic photosensitive member according to any one of claims 1 to 4.

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