JP7302266B2 - Electrophotographic photoreceptor, electrophotographic image forming method, electrophotographic image forming apparatus, and electrophotographic photoreceptor manufacturing method - Google Patents

Description

The present invention relates to an electrophotographic photoreceptor, an electrophotographic image forming method, an electrophotographic image forming apparatus, and a method for producing an electrophotographic photoreceptor, and more particularly to an electrophotographic photoreceptor excellent in abrasion resistance and image property stability. .

In recent years, the use of electrophotographic image forming apparatuses in the field of light printing is rapidly expanding, and electrophotographic photoreceptors are required to have higher durability and higher image quality. For high durability, for example, a protective layer containing a polyfunctional curable acrylate monomer (see, for example, Patent Document 1), or a protective layer using both a polymer of a monomer having a polymerizable group and fine particles (see, for example, Patent Document 2) is used.
However, when these protective layers are used, the hole transportability of the protective layer is low, and holes are accumulated at the interface between the charge transport layer and the protective layer, so that image memory tends to occur, resulting in deterioration of image quality. When a compound having a charge transport property is used in the protective layer, the hole transport property of the protective layer is improved, thereby suppressing the occurrence of image memory due to the above mechanism and leading to high image quality (see, for example, Patent Document 3). ), and sufficient durability could not be secured because the strength of the protective layer was lowered.
As described above, the conventional technology cannot provide an electrophotographic photoreceptor that is sufficiently satisfactory in terms of durability and image quality.

JP-A-8-262779 JP-A-2003-43711 Japanese Patent Application Laid-Open No. 2004-302450

The present invention has been made in view of the above problems and circumstances, and the problems to be solved are to provide excellent wear resistance, no image density difference (image memory) due to photoreceptor cycles, wear resistance and image characteristics. An object of the present invention is to provide an electrophotographic photoreceptor, an electrophotographic image forming method, an electrophotographic image forming apparatus, and a method for producing an electrophotographic photoreceptor which are excellent in the stability of the electrophotographic photoreceptor.

In order to solve the above-mentioned problems, the inventors of the present invention, in the process of studying the causes of the above-mentioned problems, found that copper (I) iodide, copper (I) bromide, and copper thiocyanate were added to the outermost surface layer of an electrophotographic photoreceptor. The present invention has found that an electrophotographic photoreceptor or the like excellent in abrasion resistance and stability of image characteristics can be provided by containing at least one copper compound selected from (I) and cuprous sulfide (I). reached.
That is, the above problems related to the present invention are solved by the following means.

1. An electrophotographic photoreceptor in which a charge generation layer, a charge transport layer and a protective layer are laminated in this order on a conductive support,
The protective layer contains at least one copper compound selected from copper (I) iodide, copper (I) bromide, copper (I) thiocyanate and copper (I) sulfide, and
The electrophotographic photosensitive material, wherein the content (parts by mass) of the copper compound in the entire protective layer is at least twice the content (parts by mass) of the charge transport agent made of an organic compound in the entire protective layer. body.

2 . 2. The electrophotographic photoreceptor of item 1, wherein the protective layer contains a resin obtained by photopolymerizing and curing a crosslinkable polymerizable compound.

3 . 3. The electrophotographic photoreceptor according to item 1 or item 2, wherein the protective layer contains oxide fine particles that are a p-type semiconductor.

4 . 4. An electrophotographic image forming method comprising using the electrophotographic photoreceptor according to any one of items 1 to 3 .

5 . An electrophotographic image forming apparatus comprising the electrophotographic photoreceptor according to any one of items 1 to 3 .

6 . A method for producing an electrophotographic photoreceptor for producing the electrophotographic photoreceptor according to any one of items 1 to 3 ,
At least one of copper(I) iodide, copper(I) bromide, copper(I) thiocyanate and copper(I) sulfide is dissolved in an organic solvent in forming the protective layer of the electrophotographic photoreceptor. A method for producing an electrophotographic photoreceptor, comprising:

7 . 7. The production of the electrophotographic photoreceptor according to item 6 , comprising a step of irradiating a protective layer coating solution containing a crosslinkable polymerizable compound with actinic rays to polymerize and cure the protective layer to form the protective layer. Method.

According to the above means of the present invention, an electrophotographic photoreceptor having excellent wear resistance, no image density difference (image memory) due to photoreceptor cycles, and excellent wear resistance and stability of image characteristics, and electrophotographic image formation. A method, an electrophotographic image forming apparatus, and a method for manufacturing an electrophotographic photoreceptor can be provided.
Although the expression mechanism or action mechanism of the effects of the present invention has not been clarified, it is speculated as follows.
One of the causes of image memory in conventional photoreceptors is a phenomenon in which holes generated during exposure are trapped inside the photosensitive layer. It is presumed that this phenomenon can be mitigated by the following mechanism.
In general, when an inorganic p-type semiconductor is added to a charge transport material that is an organic molecular material, it is necessary to reduce the charge transfer barrier at the interface between the charge transport material and the inorganic p-type semiconductor in order to maintain the hole transport performance. be. Conditions for realizing this include that the difference between the respective hole levels is small and that a dense interfacial contact structure is formed on a molecular scale.
Inorganic p-type semiconductor fine particles are usually used in the form of a dispersion. It is difficult to form a strong interfacial contact structure, resulting in an increased charge transfer barrier.
On the other hand, the monovalent copper compound according to the present invention is softer than ordinary inorganic p-type semiconductor fine particles such as oxides, and can be pulverized by a general dispersion method. can form a dense interfacial contact structure.
In particular, it is preferable to select an organic solvent in which the monovalent copper compound according to the present invention is soluble, because a denser interfacial contact structure can be formed with the charge transport material on a molecular scale. In addition, in all monovalent copper compounds according to the present invention, the 3d orbital of the copper atom forms a hole band, and the energy level is around 5.2 eV. The difference from the level energy is small. As described above, the charge transfer barrier at the interface between the monovalent copper compound and the charge transport material according to the present invention can be reduced, and the hole transport performance as a whole can be maintained.

In addition, as a means for achieving both high durability and high image quality, one solution is to eliminate the phenomenon in which holes generated during exposure are trapped at the interface between the charge transport layer and the protective layer by not providing the protective layer. The method. In this case, if a part of the charge transport material is replaced with the monovalent copper compound according to the present invention, the amount of the charge transport material acting as a plasticizer can be reduced while maintaining the hole transport performance of the charge transport layer. It is possible to achieve both high resolution and high image quality.

On the other hand, in the structure provided with the protective layer, it is more preferable from the viewpoint of high durability to eliminate the phenomenon that holes generated during exposure are trapped at the interface between the charge transport layer and the protective layer. In order to prevent trapping at the interface between the charge transport layer and the protective layer, a radically polymerizable compound having a charge transport structure described in Patent Document 3, for example, is added to the protective layer as a means for relaxing the hole transfer barrier. However, the unreacted compound remains in the protective layer and acts as a kind of plasticizer, resulting in a decrease in the strength and durability of the protective layer.
Therefore, in the protective layer according to the present invention, at the interface between the charge transport layer and the protective layer, the charge transfer barrier at the interface between the charge transport material and the monovalent copper compound according to the present invention is reduced according to the mechanism described above. It is possible to eliminate the phenomenon that holes generated during exposure are trapped at the interface between the charge transport layer and the protective layer.
In addition, since the amount of the charge transport material acting as a plasticizer in the protective layer can be minimized, sufficient durability can be ensured. In particular, when the protective layer contains oxide fine particles, which are p-type semiconductors, the strength of the protective layer increases due to the interaction with the resin molecular chains, and in addition, the hole transport property inside the protective layer also improves. Therefore, it is more preferable.
Based on the mechanism described above, it can be assumed that by using the monovalent copper compound according to the present invention, high image quality and high durability can be ensured at a sufficient level.

Schematic cross-sectional view showing an example of the electrophotographic image forming apparatus of the present invention.

The electrophotographic photoreceptor of the present invention is an electrophotographic photoreceptor in which a charge generation layer, a charge transport layer and a protective layer are laminated in this order on a conductive support,
The protective layer contains at least one copper compound selected from copper (I) iodide, copper (I) bromide, copper (I) thiocyanate and copper (I) sulfide, and
The content (parts by mass) of the copper compound in the entire protective layer is twice or more the content (parts by mass) of the charge transport agent made of an organic compound in the entire protective layer.
This feature is a technical feature common to or corresponding to each of the following embodiments.

As an embodiment of the present invention, the protective layer contains at least one copper compound selected from copper(I) iodide, copper(I) bromide, copper(I) thiocyanate and copper(I) sulfide. This is preferable in that the abrasion resistance can be further improved and the number of holes trapped at the interface between the charge transport layer and the protective layer can be reduced to prevent the occurrence of image memory.

It is preferable that the protective layer contains a resin obtained by photopolymerizing and curing a crosslinkable polymerizable compound, because the film hardness is increased and the wear resistance is further improved compared to a thermoplastic resin. .

When the protective layer contains oxide microparticles that are p-type semiconductors, a crosslinked structure is formed between the crosslinkable polymerizable compound and the oxide microparticles. It is preferable in that abrasion resistance is further improved, and the effect of introducing fine oxide particles, which are p-type semiconductors, improves the hole transport performance inside the protective layer and prevents the occurrence of image memory.

The electrophotographic photoreceptor of the present invention is suitably used for an electrophotographic image forming method and an electrophotographic image forming apparatus.

The method for producing an electrophotographic photoreceptor of the present invention is an electrophotographic photoreceptor in which a charge generation layer, a charge transport layer and a protective layer are laminated in this order on a conductive support,
The protective layer contains at least one copper compound selected from copper (I) iodide, copper (I) bromide, copper (I) thiocyanate and copper (I) sulfide, and The content (parts by mass) of the copper compound is at least twice the content (parts by mass) of the charge transport agent made of an organic compound in the entire protective layer. As a result, when an organic solvent in which copper (I) iodide, copper (I) bromide, copper (I) thiocyanate, and copper (I) sulfide are soluble is selected, the protective layer, which is the outermost layer, During formation, a denser interfacial contact structure can be formed with the charge transport material on a molecular scale, and the charge transport material and copper(I) iodide, copper(I) bromide, copper(I) thiocyanate and zinc The charge transfer barrier of copper (I) sulfide can be reduced, leading to prevention of image memory.
Further, it is preferable to include a step of irradiating a protective layer coating solution containing a crosslinkable polymerizable compound with actinic rays to polymerize and cure the protective layer to form the protective layer.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention, its constituent elements, and modes and modes for carrying out the present invention will be described below. In the present application, "-" is used to mean that the numerical values before and after it are included as the lower limit and the upper limit.

[Electrophotographic photoreceptor]
The electrophotographic photoreceptor of the present invention (hereinafter also referred to as a photoreceptor) is formed by laminating a charge generation layer and a charge transport layer in this order, or a charge generation layer, a charge transport layer and a protective layer in this order on a conductive support. wherein at least one of copper (I) iodide, copper (I) bromide, copper (I) thiocyanate and copper (I) sulfide is added to the outermost layer of the electrophotographic photoreceptor. characterized by containing one.

The photoreceptor of the present invention comprises at least a charge generation layer and a charge transport layer formed on a conductive support, and may have an intermediate layer between the conductive support and the charge generation layer. . A structure having a protective layer on the charge transport layer is preferable from the viewpoint of improving abrasion resistance. Further, it is preferable that the photosensitive layer is composed of the charge generation layer and the charge transport layer.
The layer structure of the photosensitive layer is not particularly limited, and specific layer structures including the protective layer are shown below, for example.
(1) A layer structure in which a charge-generating layer, a charge-transporting layer, and a protective layer are sequentially laminated on a conductive support (2) A single layer containing a charge-transporting substance and a charge-generating material on a conductive support A layer structure in which a layer and a protective layer are sequentially laminated (3) A layer structure in which an intermediate layer, a charge generation layer, a charge transport layer and a protective layer are sequentially laminated on a conductive support (4) A conductive support A layer structure in which an intermediate layer, a single layer containing a charge-transporting substance and a charge-generating material, and a protective layer are sequentially laminated thereon. Among them, a layer structure in which an intermediate layer, a charge generation layer, a charge transport layer and a protective layer are sequentially provided on a conductive support is particularly preferable.

<Charge transport layer>
The charge transport layer according to the present invention contains a charge transport material and a charge transport binder resin at least in the layer.
In the absence of a protective layer, copper (I) iodide, copper (I) bromide, copper (I) thiocyanate and sulfurous sulfide are added to the charge transport layer according to the present invention, which is the outermost layer of the electrophotographic photoreceptor. It contains at least one of copper (I). When a protective layer is present, at least one of copper (I) iodide, copper (I) bromide, copper (I) thiocyanate, and copper (I) sulfide is added to the protective layer, which is the outermost layer. If contained, the charge transport layer may contain at least one of copper(I) iodide, copper(I) bromide, copper(I) thiocyanate and copper(I) sulfide. It doesn't have to be.
The amounts of copper(I) iodide, copper(I) bromide, copper(I) thiocyanate and copper(I) sulfide added to the charge transport layer according to the present invention in the absence of a protective layer are It is preferably in the range of 5 to 30 parts by mass with respect to 100 parts by mass of the binder resin. When the amount is 5 parts by mass or more, the filler effect can be sufficiently exhibited, the charge transport property is good, the amount of the charge transport agent serving as a plasticizer does not need to be increased, and the decrease in film strength can be prevented. In addition, when the content is 30 parts by mass or less, the resistance and chargeability of the charge transport layer are prevented from being lowered, and the image is not fogged.

Copper (I) iodide, copper (I) bromide, copper (I) thiocyanate and cuprous (I) sulfide may be used singly, as a mixture, or as a mixed crystal.
Copper (I) iodide, copper (I) bromide, copper (I) thiocyanate, and copper (I) sulfide may be used by being mixed in the coating liquid, and after coating, impregnation, spray coating, or the like may be performed. It may be introduced using a method. In the former method of mixing in the coating liquid, for example, copper (I) iodide, copper (I) bromide, copper (I) thiocyanate and copper (I) sulfide are dispersed in an arbitrary solvent. There is a method in which a solution obtained by preparing a charge transporting material is prepared and mixed with a solution in which a charge transporting substance is dissolved in a binder resin solution for charge transporting, and the mixture is used as a coating solution.
Copper (I) iodide, copper (I) bromide, copper (I) thiocyanate and copper (I) are compatible with nitrile solvents such as acetonitrile and butyronitrile, and sulfide solvents such as dimethylsulfide and diethylsulfide. It is more preferable to use solutions using these solvents.

A known compound can be used as the charge transport material, and examples thereof include the following. That is, carbazole derivatives, oxazole derivatives, oxadiazole derivatives, thiazole derivatives, thiadiazole derivatives, triazole derivatives, imidazole derivatives, imidazolone derivatives, imidazolidine derivatives, bisimidazolidine derivatives, styryl compounds, hydrazone compounds, pyrazoline compounds, oxazolone derivatives, benz imidazole derivatives, quinazoline derivatives, benzofuran derivatives, acridine derivatives, phenazine derivatives, aminostilbene derivatives, triarylamine derivatives, phenylenediamine derivatives, stilbene derivatives, benzidine derivatives, poly-N-vinylcarbazole, poly-1-vinylpyrene and poly-9 - vinylanthracene and the like. These compounds can be used singly or in combination of two or more.

Also, known resins can be used as the binder resin for the charge transport layer, and examples thereof include the following. Examples include polycarbonate resins, polyacrylate resins, polyester resins, polystyrene resins, styrene-acrylonitrile copolymer resins, polymethacrylate resins, styrene-methacrylate copolymer resins, and the like. Among these, polycarbonate resins are preferred, and further, polycarbonate resins of types such as bisphenol A (BPA), bisphenol Z (BPZ), dimethyl BPA, and BPA-dimethyl BPA copolymers have crack resistance, abrasion resistance, and charging properties. It is preferable from the viewpoint of

(Formation of charge transport layer)
The charge transport layer can be formed by a known method typified by a coating method. For example, when a protective layer is present, a charge transport binder resin and a charge transport material are dissolved in a coating method. A desired charge-transporting layer can be formed by preparing a coating solution using a method described above, applying the coating solution to a given film thickness, and then drying the coating solution.
In the absence of a protective layer, at least one of the copper (I) iodide, copper (I) bromide, copper (I) thiocyanate and copper (I) sulfide is added to the above-described organic solvent. After dissolving to prepare a coating solution, the binder resin and the charge transporting substance are mixed with a coating solution in which the binder resin and the charge transporting substance are dissolved in the following solvent to prepare a charge transporting layer coating solution. By doing so, a charge transport layer can be formed.

Solvents for dissolving the charge-transporting binder resin and the charge-transporting substance include, for example, toluene, xylene, methyl ethyl ketone, cyclohexanone, ethyl acetate, butyl acetate, methanol, ethanol, propanol, butanol, tetrahydrofuran, 1,4-dioxane, 1 , 3-dioxolane and the like. The solvent used in preparing the coating liquid for forming the charge transport layer is not limited to the above.

The mixing ratio of the charge-transporting binder resin and the charge-transporting substance is preferably from 10 to 500 parts by mass, more preferably from 20 to 100 parts by mass, per 100 parts by mass of the charge-transporting binder resin. preferable.

The thickness of the charge-transporting layer varies depending on the properties of the charge-transporting material and the charge-transporting binder resin, the mixing ratio thereof, etc., but is preferably 5 to 40 μm, more preferably 10 to 30 μm.

A known antioxidant can be added to the charge transport layer, and for example, the antioxidant described in JP-A-2000-305291 can be used.

<Protective layer>
When a protective layer is present, the protective layer according to the present invention, which is the outermost layer of the electrophotographic photoreceptor, comprises a protective layer binder resin, copper (I) iodide, copper (I) bromide, and copper thiocyanate ( I) and at least one of cuprous sulfide (I).
The amounts of copper (I) iodide, copper (I) bromide, copper (I) thiocyanate and copper (I) sulfide added in the protective layer according to the present invention are based on 100 parts by mass of the protective layer binder resin. It is preferably within the range of 10 to 40 parts by mass. By making it 10 parts by mass or more, it is possible to impart sufficient hole transport performance to the protective layer, which is preferable. In addition, when the amount is 40 parts by mass or less, the entire amount can be dissolved in the organic solvent, so that a uniform coating liquid can be obtained, which is preferable.
Copper (I) iodide, copper (I) bromide, copper (I) thiocyanate and cuprous (I) sulfide may be used singly, as a mixture, or as a mixed crystal. It may be a mixture with other compounds, and it is more preferable from the viewpoint of wear resistance to use it in combination with oxide fine particles that are a p-type semiconductor, which will be described later.

If the volume resistivity of the protective layer is 10 ⁸ Ωcm or more, thin-line image deletion is less likely to occur, and if it is 10 ¹⁴ Ωcm or less, image memory is less likely to occur, which is preferable. The volume resistivity of the protective layer can be adjusted by adding amounts of copper (I) iodide, copper (I) bromide, copper (I) thiocyanate, and copper (I) sulfide, and is within the range of the above volume resistivity. It is preferable to add an amount that fits within.

As a method for measuring the volume resistivity, a known device (e.g., Hiresta-UP (MCP-450) manufactured by Dia Instruments Co., Ltd.) is used, under an environment of a temperature of 20 ° C. and a relative humidity of 50%, an applied voltage of 100 V (1 minute ) can be obtained by measuring

Copper (I) iodide, copper (I) bromide, copper (I) thiocyanate, and copper (I) sulfide may be used by being mixed in the coating liquid, and after coating, impregnation, spray coating, or the like may be performed. It may be introduced using a method. In the former method of mixing in the coating liquid, for example, copper (I) iodide, copper (I) bromide, copper (I) thiocyanate and copper (I) sulfide are dispersed in an arbitrary solvent. There is a method in which a solution is prepared, and this solution is mixed with a solution obtained by dissolving p-type semiconductor oxide fine particles, a charge-transporting substance, etc. .
Copper (I) iodide, copper (I) bromide, copper (I) thiocyanate and copper (I) are compatible with nitrile solvents such as acetonitrile and butyronitrile, and sulfide solvents such as dimethylsulfide and diethylsulfide. It is more preferable to use solutions using these solvents.

(Oxide fine particles that are p-type semiconductors)
Examples of fine oxide particles that are p-type semiconductors (hereinafter also simply referred to as p-type semiconductor particles) include copper (I) oxide, CuAlO ₂ , CuGaO ₂ , CuInO ₂ , SrCu ₂ O ₂ , nickel oxide (II), oxide Iron (II) and the like can be mentioned.
The average particle size of the oxide fine particles is preferably in the range of 5 to 100 nm, and the fine particles are preferably surface-treated with an organic compound such as a silane coupling agent.
The amount of the oxide particles added to the protective layer according to the present invention is preferably in the range of 20 to 100 parts by mass with respect to 100 parts by mass of the protective layer binder resin. When the amount is 20 parts by mass or more, the strength of the protective layer increases due to the interaction with the resin molecular chains, and the hole transport property inside the protective layer also improves, which is preferable. When the amount is 100 parts by mass or less, the dispersed state of the coating liquid particles is easily stabilized, which is preferable.

(Surface-treated p-type semiconductor particles)
The p-type semiconductor particles are preferably treated with a surface treating agent, more preferably with a surface treating agent having a reactive organic group.

(Surface treatment agent)
As the surface treatment agent according to the present invention, a surface treatment agent that reacts with hydroxy groups or the like present on the surface of the p-type semiconductor particles is preferable. Examples of these surface treatment agents include silane coupling agents, titanium coupling agents, and the like. mentioned.
In the present invention, a surface treatment agent having a reactive organic group is preferable for the purpose of further increasing the hardness of the protective layer. Treatment agents are preferred. These radically polymerizable reactive groups can also react with the polymerizable compound according to the present invention to form a strong protective film. As the surface treatment agent having a radically polymerizable reactive group, a silane coupling agent having a radically polymerizable reactive group such as a vinyl group or an acryloyl group is preferable. As the surface treatment agent having such a radically polymerizable reactive group, Known compounds as described below are exemplified.

S-1: CH ₂ =CHSi(CH ₃ )(OCH ₃ ) ₂
S-2: CH ₂ =CHSi(OCH ₃ ) ₃
S-3: CH ₂ =CHSiCl ₃
S-4: _CH2 =CHCOO( _CH2 ) _2Si ( _CH3 )( _OCH3 ) ₂
S-5: _CH2 =CHCOO( _CH2 ) _2Si ( _OCH3 ) ₃
S-6: _CH2 =CHCOO( _CH2 ) _{2Si ( OC2H5} )( _OCH3 ) ₂
S-7: _CH2 =CHCOO( _CH2 ) _3Si ( _OCH3 ) ₃
S-8: _CH2 =CHCOO( _CH2 ) _2Si ( _CH3 ) _Cl2
S-9: _CH2 =CHCOO _{( CH2} ) _2SiCl3
S-10: _CH2 =CHCOO( _CH2 ) _3Si ( _CH3 ) _Cl2
S -11: _CH2 =CHCOO( _CH2 ) _3SiCl3
S-12: _CH2 =C( _CH3 )COO( _CH2 ) _2Si ( _CH3 )( _OCH3 ) ₂
S-13: _CH2 =C( _CH3 )COO( _CH2 ) _2Si ( _OCH3 ) ₃
S-14: _CH2 =C( _CH3 )COO( _CH2 ) _3Si ( _CH3 )( _OCH3 ) ₂
S-15: _CH2 =C( _CH3 )COO( _CH2 ) _3Si ( _OCH3 ) ₃
S-16: _CH2 =C( _CH3 )COO( _CH2 ) _2Si ( _CH3 ) _Cl2
S-17: _CH2 =C( _CH3 ) _COO ( _CH2 ) _2SiCl3
S-18: _CH2 =C( _CH3 )COO( _CH2 ) _3Si ( _CH3 ) _Cl2
S-19: _CH2 =C( _CH3 ) _COO ( _CH2 ) _3SiCl3
S-20 _{: CH2} =CHSi( _C2H5 )( _OCH3 ) ₂
S-21: CH ₂ =C(CH ₃ )Si(OCH ₃ ) ₃
S- ₂₂ : _CH2 =C( _CH3 )Si( _OC2H5 ) ₃
S-23: CH ₂ =CHSi(OCH ₃ ) ₃
S-24: CH ₂ =C(CH ₃ )Si(CH ₃ )(OCH ₃ ) ₂
S-25: _CH2 =CHSi( _CH3 ) _Cl2
S-26: _CH2 =CHCOOSi( _OCH3 ) ₃
S-27: _CH2 = _CHCOOSi ( _OC2H5 ) ₃
S-28: _CH2 =C( _CH3 )COOSi( _OCH3 ) ₃
S- ₂₉ : _CH2 =C( _CH3 )COOSi( _OC2H5 ) ₃
S- ₃₀ : _CH2 =C( _CH3 )COO( _CH2 ) _3Si ( _OC2H5 ) ₃
S-31: _CH2 =CHCOO( _CH2 ) _2Si ( _CH3 ) ₂ ( _OCH3 )
S-32: _CH2 =CHCOO( _CH2 ) _2Si ( _CH3 )( _OCOCH3 ) ₂
S-33: _CH2 =CHCOO( _CH2 ) _2Si ( _CH3 )( _ONHCH3 ) _2
S -34: _CH2 =CHCOO( _CH2 ) _2Si ( _CH3 )( _OC6H5 ) ₂
S- ₃₅ : _CH2 =CHCOO( _CH2 ) _2Si ( _C10H21 )( _OCH3 ) ₂
S-36 _{: CH2} =CHCOO _{( CH2} ) _2Si ( _CH2C6H5 )( _OCH3 ) ₂

In addition to the above S-1 to S-36, a silane compound having a radically polymerizable reactive organic group may be used as the surface treatment agent. These surface treatment agents can be used alone or in combination of two or more.

(Method for producing surface-treated p-type semiconductor particles)
In the surface treatment, 0.1 to 100 parts by mass of a surface treatment agent and 50 to 5000 parts by mass of a solvent are preferably used for 100 parts by mass of particles, using a wet media dispersion type apparatus. It can also be processed dry.

A surface treatment method for producing metal oxide particles uniformly surface-treated with a surface treatment agent will be described below.

That is, by wet pulverizing a slurry (suspension of solid particles) containing p-type semiconductor particles and a surface treatment agent, the p-type semiconductor particles are made finer and the surface treatment of the particles proceeds. Thereafter, the solvent is removed and pulverized to obtain p-type semiconductor particles uniformly surface-treated with a surface treatment agent.

The wet media dispersion type device, which is a surface treatment device used in the present invention, fills a container with beads as media, and further rotates a stirring disk attached perpendicularly to the rotating shaft at high speed to obtain a p-type semiconductor. An apparatus having a process of crushing, pulverizing, and dispersing agglomerated particles, and having a configuration in which p-type semiconductor particles can be sufficiently dispersed and surface-treated when p-type semiconductor particles are surface-treated. Various modes such as vertical/horizontal type, continuous/batch type, etc. can be adopted without any problem. Specifically, sand mills, ultravisco mills, pearl mills, grain mills, dyno mills, agitator mills, dynamic mills and the like can be used. These dispersing devices use grinding media such as balls and beads to perform fine grinding and dispersion by impact crushing, friction, shearing, shear stress, and the like.

As the beads used in the above wet media dispersion type apparatus, balls made of glass, alumina, zircon, zirconia, steel, flint stone, etc. can be used as raw materials, but those made of zirconia or zircon are particularly preferable. As for the size of beads, beads with a diameter of about 1 to 2 mm are usually used, but in the present invention, beads with a diameter of about 0.1 to 1.0 mm are preferably used.

Various materials such as stainless steel, nylon, and ceramics can be used for the disk and inner wall of the container used in the wet media dispersion type apparatus. is preferred.

By the wet treatment as described above, p-type semiconductor particles surface-treated with a surface-treating agent can be obtained.

The protective layer binder resin preferably contains a resin obtained by photopolymerizing and curing a crosslinkable polymerizable compound (also referred to as a curable compound).
Other than polymerizable compounds, known resins such as polyester resins, polycarbonate resins, polyurethane resins and silicone resins can be used. A polymerizable compound and a resin other than the polymerizable compound can also be used in combination.

(Polymerizable compound)
Examples of the polymerizable compound that can be used in the protective layer according to the present invention include radically polymerizable compounds, and the radically polymerizable compound has at least one of an acryloyl group and a methacryloyl group as a radically polymerizable reactive group. Polymerizable monomers are preferred.

Examples of these polymerizable monomers include the following compounds, but the polymerizable monomers that can be used in the present invention are not limited to these.

The above radically polymerizable compounds are known and available as commercial products.
Here, R represents the following acryloyl group, and R' represents the following methacryloyl group.

In addition to these, the protective layer according to the present invention may be formed by containing a polymerization initiator, lubricant particles, and the like, if necessary.

(Polymerization initiator)
As a method for curing the polymerizable compound that can be used in the protective layer according to the present invention, the curing reaction is performed by a method using electron beam cleavage reaction, a method using light or heat in the presence of a radical polymerization initiator, or the like. It can be carried out. When the curing reaction is performed using a radical polymerization initiator, both a photopolymerization initiator and a thermal polymerization initiator can be used as the polymerization initiator. Moreover, both photoinitiators and thermal initiators can be used together.

Polymerization initiators that can be used in the present invention include 2,2′-azobisisobutyronitrile, 2,2′-azobis(2,4-dimethylazobisvaleronyl), 2,2′-azobis(2 -methylbutyronitrile), benzoyl peroxide (BPO), di-tert-butyl hydroperoxide, tert-butyl hydroperoxide, chlorobenzoyl peroxide, dichlorobenzoyl peroxide, bromomethylbenzoyl peroxide, peroxide Thermal polymerization initiators such as peroxides such as lauroyl can be used.

Further, as a photopolymerization initiator, diethoxyacetophenone, 2,2-dimethoxy-1,2-diphenylethan-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, 4-(2-hydroxyethoxy)phenyl- (2-hydroxy-2-propyl) ketone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl) butanone-1 (Irgacure 369: manufactured by BASF Japan), 2-hydroxy-2-methyl- 1-phenylpropan-1-one, 2-methyl-2-morpholino(4-methylthiophenyl)propan-1-one, 1-phenyl-1,2-propanedione-2-(o-ethoxycarbonyl)oxime and the like Acetophenone or ketal photoinitiators, benzoin ether photoinitiators such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isobutyl ether, benzoin isopropyl ether, benzophenone, 4-hydroxybenzophenone, methyl o-benzoylbenzoate , 2-benzoylnaphthalene, 4-benzoylbiphenyl, 4-benzoylphenyl ether, acrylated benzophenone, benzophenone-based photopolymerization initiators such as 1,4-benzoylbenzene, 2-isopropylthioxanthone, 2-chlorothioxanthone, 2,4- Thioxanthone-based photopolymerization initiators such as dimethylthioxanthone, 2,4-diethylthioxanthone, and 2,4-dichlorothioxanthone are included.

Other photoinitiators include ethyl anthraquinone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylethoxyphosphine oxide, bis(2,4,6-trimethylbenzoyl)phenylphosphine. Oxide (Irgacure 819: manufactured by BASF Japan), bis(2,4-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide, methylphenylglyoxyester, 9,10-phenanthrene, acridine compound, triazine compounds and imidazole compounds. In addition, one having a photopolymerization promoting effect can be used alone or in combination with the photopolymerization initiator. Examples include triethanolamine, methyldiethanolamine, ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, (2-dimethylamino)ethyl benzoate, 4,4'-dimethylaminobenzophenone and the like.

The polymerization initiator used in the present invention is preferably a photopolymerization initiator, preferably an alkylphenone compound or a phosphine oxide compound, more preferably an initiator having an α-hydroxyacetophenone structure or an acylphosphine oxide structure. preferable.

These polymerization initiators may be used singly or in combination of two or more. The content of the polymerization initiator is in the range of 0.1 to 40 parts by mass, preferably 0.5 to 20 parts by mass, per 100 parts by mass of the polymerizable compound.

(Lubricant particles)
It is also possible to incorporate various lubricant particles into the protective layer. For example, fluorine atom-containing resin particles can be added.
Examples of fluorine atom-containing resin particles include tetrafluoroethylene resin, trifluoroethylene chloride resin, hexafluoroethylene chloride propylene resin, vinyl fluoride resin, vinylidene fluoride resin, difluorodichloride ethylene resin, and these resins. It is preferable to appropriately select one or more of the copolymers, and tetrafluoroethylene resin and vinylidene fluoride resin are particularly preferable.

The protective layer may contain a charge transporting agent (charge transporting substance) composed of an organic compound, but it is preferably added in an amount of 10 parts by mass or less per 100 parts by mass of the binder resin for the protective layer in order to maintain abrasion resistance. Specific examples of compounds include compounds having a triphenylamine skeleton exemplified in paragraphs [0050] to [0060] of JP-A-2015-169870.

(solvent)
Solvents for dissolving the radically polymerizable compound and p-type semiconductor particles include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-2-propanol, benzyl alcohol, methyl isopropyl ketone, methyl isobutyl ketone, methyl ethyl ketone, cyclohexane, toluene, xylene, methylene chloride, ethyl acetate, butyl acetate, 2-methoxyethanol, 2-ethoxyethanol, tetrahydrofuran, 1-dioxane, 1,3-dioxolane, pyridine and diethylamine, but are not limited to these.

(Formation of protective layer)
The protective layer is prepared by dissolving at least one of copper (I) iodide, copper (I) bromide, copper (I) thiocyanate and copper (I) sulfide in the above organic solvent to prepare a coating solution. , a radically polymerizable compound, optionally surface-treated p-type semiconductor particles, a known resin, a polymerization initiator, lubricant particles, an antioxidant, a charge transport agent, etc. dissolved in the solvent. These two coating solutions are mixed to prepare a coating solution for forming a protective layer, the coating solution is applied to the surface of the photosensitive layer, dried naturally or by heat, and then cured. can.
The film thickness of the protective layer is preferably 0.2 to 10 μm, more preferably 0.5 to 6 μm.

In the present invention, the protective layer is cured by irradiating the coating film with an actinic ray to generate radicals for polymerization, and by forming cross-linking bonds due to cross-linking reactions between molecules and within molecules to cure and generate a cured resin. preferably. As the actinic rays, light such as ultraviolet rays, visible light, and electron beams are preferable, and ultraviolet rays are particularly preferable from the standpoint of ease of use.

As the ultraviolet light source, any light source that generates ultraviolet light can be used without limitation. For example, low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, carbon arc lamps, metal halide lamps, xenon lamps, flash (pulse) xenon, ultraviolet LEDs, and the like can be used. Irradiation conditions vary depending on each lamp, but the irradiation dose of actinic rays is usually 1 to 20 mJ/cm ² , preferably 5 to 15 mJ/cm ² . The output voltage of the light source is preferably 0.1-5 kW, particularly preferably 0.5-3 kW.

As an electron beam source, there are no particular restrictions on the electron beam irradiation apparatus, and in general, curtain beam type electron beam accelerators, which are relatively inexpensive and can produce a large output, are effective as electron beam accelerators for such electron beam irradiation. Used. The acceleration voltage for electron beam irradiation is preferably 100 to 300 kV. The absorbed dose is preferably 0.005 Gy to 100 kGy (0.5 to 10 Mrad).

The irradiation time of actinic rays is the time required to obtain the required irradiation dose of actinic rays, specifically preferably 0.1 seconds to 10 minutes, more preferably 1 second to 5 minutes from the viewpoint of curing efficiency or work efficiency. It is said that

In the present invention, the protective layer can be dried before and after irradiation with actinic rays and during irradiation with actinic rays, and the timing of drying can be appropriately selected in combination with the irradiation conditions of actinic rays. The drying conditions for the protective layer can be appropriately selected according to the type of solvent used in the coating liquid, the film thickness of the protective layer, and the like. The drying temperature is preferably room temperature to 180°C, particularly preferably 80 to 140°C. The drying time is preferably 1 to 200 minutes, particularly preferably 5 to 100 minutes. In the present invention, the amount of solvent contained in the protective layer can be controlled within the range of 20 to 75 ppm by drying the protective layer under the above drying conditions.

<Conductive support>
The support used in the present invention may be any material as long as it has conductivity. Laminated metal foil such as or copper on plastic film, vapor-deposited aluminum, indium oxide, tin oxide, etc. on plastic film, metal with a conductive layer coated with a conductive substance alone or with a binder resin, plastic film and paper;

<Middle layer>
In the present invention, an intermediate layer having a barrier function and an adhesive function can be provided between the conductive support and the charge generation layer.
The intermediate layer can be formed by dissolving an intermediate layer binder resin such as casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, polyamide, polyurethane and gelatin in a known solvent and dip coating. Among the binder resins for the intermediate layer, alcohol-soluble polyamide resins are preferable.

Further, the intermediate layer may contain various conductive fine particles and metal oxide particles for the purpose of resistance adjustment. For example, various metal oxide particles such as alumina, zinc oxide, titanium oxide, tin oxide, antimony oxide, indium oxide and bismuth oxide. Ultrafine particles such as tin-doped indium oxide, antimony-doped tin oxide and zirconium oxide can be used. These metal oxide particles can be used singly or in combination of two or more. When two or more types are mixed and used, they may take the form of a solid solution or fusion bonding.
Such metal oxide particles preferably have a number average primary particle size of 0.3 μm or less, more preferably 0.1 μm or less.

As a solvent that can be used for forming the intermediate layer, a solvent that can well disperse the inorganic fine particles such as the conductive fine particles and the metal oxide particles described above and dissolve the binder resin for the intermediate layer such as the polyamide resin is preferable.
Specifically, alcohols having 2 to 4 carbon atoms such as ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol, t-butanol, and sec-butanol are preferred polyamide resins as binder resins for intermediate layers. It is preferable because it expresses good solubility and coating performance for.
Further, in order to improve storage stability and dispersibility of inorganic fine particles, the following co-solvents can be used in combination with the solvent. Examples of co-solvents that produce favorable effects include methanol, benzyl alcohol, toluene, cyclohexanone, tetrahydrofuran, and the like.

The concentration of the binder resin for the intermediate layer when forming the coating liquid can be appropriately selected according to the thickness of the intermediate layer and the coating method. Further, when the inorganic fine particles are dispersed, the mixing ratio of the inorganic fine particles to the binder resin for the intermediate layer is preferably 20 to 400 parts by mass with respect to 100 parts by mass of the binder resin for the intermediate layer. It is more preferable to be in the range of up to 200 parts by mass.

Examples of means for dispersing inorganic fine particles include, but are not limited to, an ultrasonic disperser, a ball mill, a sand grinder, a homomixer, and the like.

As for the drying method of the intermediate layer, a known drying method can be appropriately selected according to the type of solvent and the film thickness to be formed, and heat drying is particularly preferable.

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

<Charge generation layer>
The charge-generating layer according to the present invention contains a charge-generating substance and a binder resin for the charge-generating layer, and is formed by applying a coating liquid in which the charge-generating substance is dispersed in a binder resin solution for the charge-generating layer. is preferred.

Examples of charge-generating substances include azo raw materials such as Sudan Red and Diane Blue, quinone pigments such as pyrenequinone and anthanthrone, quinocyanine pigments, perylene pigments, indigo pigments such as indigo and thioindigo, and phthalocyanine pigments, but are limited to these. isn't it. These charge-generating substances can be used alone or in the form of being dispersed in a known binder resin.

Known resins can be used as the binder resin for forming the charge generation layer. Resins, polyurethane resins, phenolic resins, polyester resins, alkyd resins, polycarbonate resins, silicone resins, melamine resins, and copolymer resins containing two or more of these resins (for example, vinyl chloride-vinyl acetate copolymer resins , vinyl chloride-vinyl acetate-maleic anhydride copolymer resin) and poly-vinylcarbazole resin, but are not limited thereto.

The charge-generating layer is formed by dispersing the charge-generating substance in a solution prepared by dissolving the binder resin for the charge-generating layer in a solvent using a dispersing machine to prepare a coating liquid, and applying the coating liquid to a predetermined thickness with a coating machine. It is preferable to prepare by coating and drying the coating film.

Solvents for dissolving and applying the charge generation layer binder resin include, for example, toluene, xylene, methyl ethyl ketone, cyclohexane, ethyl acetate, butyl acetate, methanol, ethanol, propanol, butanol, methyl cellosolve, ethyl cellosolve, tetrahydrofuran, 1 -dioxane, 1,3-dioxolane, pyridine and diethylamine, and the like, but are not limited to these.

As a means for dispersing the charge-generating substance, an ultrasonic dispersing machine, a ball mill, a sand grinder, a homomixer, or the like can be used, but the means is not limited to these.

The mixing ratio of the charge generation material to the charge generation layer binder resin is preferably 1 to 600 parts by weight, more preferably 50 to 500 parts by weight, per 100 parts by weight of the charge generation layer binder resin. The thickness of the charge generation layer varies depending on the properties of the charge generation material, the properties of the binder resin for the charge generation layer, the mixing ratio, etc., but is preferably 0.01 to 5 μm, more preferably 0.05 to 3 μm.
Incidentally, the coating liquid for the charge generation layer can be prevented from generating image defects by filtering foreign matters and aggregates before coating. It can also be formed by vacuum deposition of the pigment.

[Coating method of photoreceptor]
Each layer such as the intermediate layer, charge generating layer, charge transporting layer, and protective layer constituting the photoreceptor of the present invention can be formed by a known coating method. Specific examples thereof include dip coating, spray coating, spinner coating, bead coating, blade coating, beam coating, circular amount control coating, and the like. The circular amount-regulating coating method is described, for example, in JP-A-58-189061 and JP-A-2005-275373.

[Electrophotographic image forming apparatus]
An electrophotographic image forming apparatus of the present invention is characterized by comprising the above-described electrophotographic photoreceptor of the present invention.
Specifically, the electrophotographic image forming apparatus of the present invention (hereinafter also referred to as an image forming apparatus) includes (1) at least the electrophotographic photoreceptor of the present invention, and (2) a charging device for charging the surface of the above-described electrophotographic photoreceptor. (3) exposure means for performing image exposure on the surface of the electrophotographic photosensitive member charged by the charging means to form a latent image; (4) visualizing the latent image formed by the exposure means to form a toner image; (5) transfer means for transferring the toner image formed on the surface of the electrophotographic photosensitive member by the development means onto a transfer medium such as paper or a transfer belt.

A non-contact charging device is preferably used as charging means for charging the electrophotographic photosensitive member. Examples of non-contact charging devices include corona charging devices, corotron charging devices, and scorotron charging devices.

FIG. 1 is a cross-sectional configuration diagram for explaining an example of a color image forming apparatus showing one embodiment of the present invention.
This color image forming apparatus is called a tandem type color image forming apparatus, and includes four sets of image forming portions (image forming units) 10Y, 10M, 10C, and 10Bk, an endless belt-like intermediate transfer member unit 7, and a feeder. It consists of paper transport means 21 and fixing means 24 . A document image reading device SC is arranged on the upper part of the main body A of the image forming apparatus.

The image forming unit 10Y for forming a yellow image includes charging means (charging process) 2Y, exposure means (exposure process) 3Y, and developing means, which are arranged around a drum-shaped photoreceptor 1Y as a first image carrier. It has a means (development process) 4Y, a primary transfer roller 5Y as a primary transfer means (primary transfer process), and a cleaning means 6Y. The image forming section 10M for forming a magenta image includes a drum-shaped photosensitive member 1M as a first image bearing member, charging means 2M, exposure means 3M, developing means 4M, primary transfer roller 5M as primary transfer means, It has cleaning means 6M. The image forming section 10C for forming a cyan image includes a drum-shaped photosensitive member 1C as a first image bearing member, charging means 2C, exposure means 3C, developing means 4C, primary transfer roller 5C as primary transfer means, It has cleaning means 6C. An image forming section 10Bk for forming a black image includes a drum-shaped photosensitive member 1Bk as a first image bearing member, charging means 2Bk, exposure means 3Bk, developing means 4Bk, primary transfer roller 5Bk as primary transfer means, and cleaning means. 6Bk.

The four sets of image forming units 10Y, 10M, 10C and 10Bk are composed mainly of photosensitive drums 1Y, 1M, 1C and 1Bk, charging means 2Y, 2M, 2C and 2Bk, image exposing means 3Y, 3M and 3C, 3Bk, developing means 4Y, 4M, 4C and 4Bk, and cleaning means 6Y, 6M, 6C and 6Bk for cleaning the photosensitive drums 1Y, 1M, 1C and 1Bk.

The image forming units 10Y, 10M, 10C, and 10Bk have the same configuration except that the colors of the toner images formed on the photoreceptors 1Y, 1M, 1C, and 1Bk are different. to explain.

The image forming unit 10Y includes a charging device 2Y (hereinafter simply referred to as charging device 2Y or charging device 2Y), an exposure device 3Y, a developing device 4Y, and a cleaning device 6Y ( Hereinafter, simply referred to as cleaning means 6Y or cleaning blade 6Y) is arranged to form a yellow (Y) toner image on the photosensitive drum 1Y. Further, in this embodiment, at least the photosensitive drum 1Y, the charging means 2Y, the developing means 4Y, and the cleaning means 6Y of the image forming unit 10Y are integrated.

The charging means 2Y is means for applying a uniform potential to the photosensitive drum 1Y, and in the present embodiment, a corona discharge charger 2Y is used for the photosensitive drum 1Y.

The image exposure means 3Y performs exposure based on an image signal (yellow) on the photosensitive drum 1Y to which a uniform potential is applied by the charger 2Y to form an electrostatic latent image corresponding to the yellow image. The exposure means 3Y is composed of an LED having light emitting elements arranged in an array in the axial direction of the photosensitive drum 1Y and an imaging element (trade name: Selfoc (registered trademark) lens). , or a laser optical system or the like is used.

The image forming apparatus of the present invention is configured by integrally connecting the photoreceptor, the developing device, the cleaning device, and other components as a process cartridge (image forming unit), and the image forming unit is attached to the main body of the apparatus. It may be configured to be detachable. At least one of a charging device, an image exposing device, a developing device, a transferring or separating device, and a cleaning device is integrally supported together with a photosensitive member to form a process cartridge (image forming unit), which is detachably attachable to the apparatus main body. A single image forming unit may be used, and may be detachable using a guide means such as a rail of the apparatus main body.

The endless belt-shaped intermediate transfer member unit 7 has an endless belt-shaped intermediate transfer member 70 as a second semi-conductive endless belt-shaped image bearing member wound around a plurality of rollers and rotatably supported.

Images of respective colors formed by the image forming units 10Y, 10M, 10C, and 10Bk are sequentially transferred onto a rotating endless belt-shaped intermediate transfer member 70 by primary transfer rollers 5Y, 5M, 5C, and 5Bk as primary transfer means. to form a composite color image. A transfer material P as a transfer material (a support for carrying the final fixed image: for example, plain paper, transparent sheet, etc.) accommodated in a paper feed cassette 20 is fed by a paper feed means 21 and fed to a plurality of intermediate sheets. After passing through rollers 22A, 22B, 22C, 22D and a registration roller 23, the image is conveyed to a secondary transfer roller 5b as a secondary transfer means, and is secondary-transferred onto the transfer material P to collectively transfer the color image. The transfer material P onto which the color image has been transferred is subjected to fixing processing by the fixing means 24 , sandwiched between the paper discharge rollers 25 and placed on the paper discharge tray 26 outside the apparatus. Here, a transfer support for a toner image formed on a photosensitive member such as an intermediate transfer member or a transfer material is generally referred to as a transfer medium.

On the other hand, after the color image has been transferred onto the transfer material P by the secondary transfer roller 5b as a secondary transfer means, the endless belt-like intermediate transfer body 70, which has separated the transfer material P by curvature, is cleaned of residual toner by the cleaning means 6b. be.

During the image forming process, the primary transfer roller 5Bk is always in contact with the photoreceptor 1Bk. The other primary transfer rollers 5Y, 5M and 5C are in contact with the corresponding photoreceptors 1Y, 1M and 1C only during color image formation.

The secondary transfer roller 5b contacts the endless belt-like intermediate transfer member 70 only when the transfer material P passes through it and secondary transfer is performed.

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

A housing 8 includes image forming units 10Y, 10M, 10C, and 10Bk, and an endless belt-like intermediate transfer member unit 7 .

The image forming units 10Y, 10M, 10C, and 10Bk are arranged vertically in tandem. An endless belt-shaped intermediate transfer member unit 7 is arranged on the left side of the photoreceptors 1Y, 1M, 1C, and 1Bk in the drawing. The endless belt-shaped intermediate transfer member unit 7 includes an endless belt-shaped intermediate transfer member 70 that can be rotated by winding rollers 71, 72, 73, and 74, primary transfer rollers 5Y, 5M, 5C, and 5Bk, and cleaning means 6b. consists of

EXAMPLES The present invention will be specifically described below with reference to Examples, but the present invention is not limited to these. In the following examples, unless otherwise specified, operations were performed at room temperature (25°C). Moreover, unless otherwise specified, "%" and "parts" mean "% by mass" and "parts by mass" respectively.

[Preparation of Photoreceptor 1]
Photoreceptor 1 was produced as follows.
<Conductive support>
A conductive support having a surface roughness Rz of 1.5 (μm) was prepared by cutting the surface of a cylindrical aluminum support having a diameter of 60 mm.

<Middle layer>
A dispersion liquid having the following composition was diluted twice with the same mixed solvent, allowed to stand overnight, and then filtered (filter: using a ligimesh 5 μm filter manufactured by Nippon Pall Co., Ltd.) to prepare an intermediate layer coating liquid.
Binder resin for intermediate layer: Polyamide resin CM8000 (manufactured by Toray Industries, Inc.): 1 part by mass Titanium oxide SMT500SAS (manufactured by Tayca Corporation): 3 parts by mass Methanol: 10 parts by mass A sand mill was used as a disperser to disperse batchwise for 10 hours. did
The above coating solution was applied onto the support by dip coating so as to give a dry film thickness of 2 μm.

<Charge generation layer>
Charge-generating substance: titanyl phthalocyanine pigment (titanyl phthalocyanine pigment having a maximum diffraction peak at at least 27.3° in Cu-Kα characteristic X-ray diffraction spectrum measurement): 20 parts by mass Binder resin for charge-generating layer: polyvinyl butyral resin (#6000-C: manufactured by Denki Kagaku Kogyo Co., Ltd.): 10 parts by mass t-butyl acetate: 700 parts by mass 4-methoxy-4-methyl-2-pentanone: 300 parts by mass Mix the above components and use a sand mill to make 10 After dispersion over time, a charge generation layer coating solution was prepared. This coating solution was applied onto the intermediate layer by a dip coating method to form a charge generation layer having a dry film thickness of 0.3 μm.

<Charge transport layer>
Charge transport material (4,4′-dimethyl-4″-(β-phenylstyryl)triphenylamine): 225 parts by mass Binder resin for charge transport layer: Polycarbonate (Z-300: manufactured by Mitsubishi Gas Chemical Company): 300 mass Part antioxidant (Irganox 1010: manufactured by BASF Japan): 6 parts by mass Tetrahydrofuran: 1600 parts by mass Toluene: 400 parts by mass Silicone oil (KF-54: manufactured by Shin-Etsu Chemical Co., Ltd.): 1 part by mass Mix and dissolve the above components. A coating solution for the charge transport layer was prepared by applying this coating solution on the charge generation layer by a dip coating method to form a charge transport layer having a dry film thickness of 20 μm.

<Protective layer>
・Protective layer coating solution (1)
Copper (I) iodide (manufactured by Wako Pure Chemical Industries, Ltd.): 20 parts by mass Acetonitrile: 500 parts by mass The above components were mixed and stirred to obtain an acetonitrile solution of copper (I) iodide.

・Protective layer coating solution (2)
CuAlO ₂ particles (particles with an average primary particle diameter of 20 nm synthesized by the method described in JP-A-2015-230431 and surface-treated with a silane coupling agent KBM-503 (manufactured by Shin-Etsu Chemical Co., Ltd.)): 80 parts by mass Protection Layer binder resin (polymerizable compound: Sartomer SR-350: trimethylolpropane trimethacrylate): 100 parts by weight polymerization initiator (Irgacure 819: manufactured by BASF Japan): 15 parts by weight 2-butanol: 500 parts by weight After the above components were mixed and stirred and fully dissolved, they were dispersed using an ultrasonic homogenizer to obtain a coating liquid (2). Subsequently, the coating liquid (1) was added to the coating liquid (2) and dispersed again using an ultrasonic homogenizer to prepare a protective layer coating liquid. Using a circular slide hopper coating machine, a protective layer was coated on the photoreceptor on which the coating liquid up to the charge transport layer had been previously prepared. After the application, ultraviolet rays were irradiated for 1 minute using a xenon lamp to obtain a protective layer having a dry film thickness of 2.0 μm. Thus, "Photoreceptor 1" was produced.

[Preparation of Photoreceptor 2]
In the preparation of photoreceptor 1, copper (I) iodide (manufactured by Wako Pure Chemical Industries, Ltd.) in protective layer coating solution (1) was changed to copper (I) bromide (manufactured by Wako Pure Chemical Industries, Ltd.). Photoreceptor 2 was obtained in the same manner.

[Preparation of Photoreceptor 3]
In the preparation of photoreceptor 1, copper (I) iodide (manufactured by Wako Pure Chemical Industries, Ltd.) in protective layer coating liquid (1) was changed to copper (I) thiocyanate (manufactured by Wako Pure Chemical Industries, Ltd.). Photoreceptor 3 was obtained in the same manner.

[Production of Photoreceptor 4]
In the production of photoreceptor 1, except that copper (I) iodide (manufactured by Wako Pure Chemical Industries, Ltd.) in protective layer coating liquid (1) was changed to cuprous (I) sulfide (manufactured by Mitsuwa Kagaku Co., Ltd.) , Photoreceptor 4 was obtained in the same manner.

[Production of Photoreceptor 5]
In the preparation of photoreceptor 1, the addition amount of copper (I) iodide (manufactured by Wako Pure Chemical Industries, Ltd.) in protective layer coating solution (1) was 10 parts by mass, and CuAlO ₂ particles in protective layer coating solution (2) were added. Photoreceptor 5 was obtained in the same manner, except that the amount was changed to 90 parts by mass.

[Production of Photoreceptor 6]
In the preparation of photoreceptor 1, the addition amount of copper (I) iodide (manufactured by Wako Pure Chemical Industries, Ltd.) in protective layer coating solution (1) was 30 parts by mass, and CuAlO ₂ particles in protective layer coating solution (2) were added. Photoreceptor 6 was obtained in the same manner, except that the amount was changed to 70 parts by mass.

[Production of Photoreceptor 7]
In the preparation of photoreceptor 1, the addition amount of copper (I) iodide (manufactured by Wako Pure Chemical Industries, Ltd.) in protective layer coating solution (1) was 10 parts by mass, and CuAlO ₂ particles in protective layer coating solution (2) were added. Photoreceptor 7 was obtained in the same manner, except that the amount was changed to 20 parts by mass.

[Production of Photoreceptor 8]
In the preparation of photoreceptor 1, 20 parts by mass of copper (I) iodide (manufactured by Wako Pure Chemical Industries, Ltd.) in protective layer coating solution (1) was changed to 40 parts by mass of copper (I) bromide (manufactured by Wako Pure Chemical Industries, Ltd.). Photoreceptor 8 was obtained in the same manner, except that the amount of CuAlO ₂ particles added in protective layer coating solution (2) was changed to 60 parts by mass.

[Production of Photoreceptor 9]
In the preparation of the photoreceptor 1, the CuAlO ₂ particles in the protective layer coating liquid (2) were used as copper (I) oxide particles (EM Japan Co., Ltd.: particles having an average primary particle diameter of 18 nm were used as a silane coupling agent KBM-503 (manufactured by Shin-Etsu Chemical Co., Ltd.). Photoreceptor 9 was obtained in the same manner, except that the surface treatment was changed to ).

[Production of Photoreceptor 10]
In the preparation of the photoreceptor 1, the CuAlO ₂ particles of the protective layer coating liquid (2) were replaced with nickel (II) oxide particles (Ioritec Co., Ltd.: particles with an average primary particle size of 20 nm were added with a silane coupling agent KBM-503 (manufactured by Shin-Etsu Chemical Co., Ltd.). Photoreceptor 10 was obtained in the same manner.

[Production of Photoreceptor 11]
Photoreceptor 11 was obtained in the same manner as Photoreceptor 1 except that acetonitrile in protective layer coating solution (1) was changed to butyronitrile.

[Production of Photoreceptor 12]
Photoreceptor 12 was obtained in the same manner as Photoreceptor 1 except that acetonitrile in protective layer coating solution (1) was changed to diethyl sulfide.

[Production of Photoreceptor 13]
In the production of Photoreceptor 1, the binder resin of protective layer coating liquid (2) was changed from SR-350 (trimethylolpropane trimethacrylate) manufactured by Sartomer to SR-355 (ditrimethylolpropane tetraacrylate) manufactured by Sartomer. Photoreceptor 13 was obtained in the same manner except for the above.

[Production of Photoreceptor 14]
In the preparation of photoreceptor 1, the amount of CuAlO ₂ particles added to protective layer coating solution (2) was changed to 70 parts by mass, and 10 parts by mass of CTM-1 (4-propylbiphenyldiphenylamine) was added as a charge transport material. Photoreceptor 14 was obtained in the same manner except for the above.

[Production of Photoreceptor 15]
In the preparation of Photoreceptor 1, the amount of CuAlO ₂ particles added to protective layer coating liquid (2) was changed to 70 parts by mass, and the binder resin was changed from SR-350 (trimethylolpropane trimethacrylate) manufactured by Sartomer Co. to polycarbonate EZ- 5030 (manufactured by Mitsubishi Gas Chemical Co., Ltd.), 500 parts by mass of 2-butanol was changed to a mixed solvent of 400 parts by mass of tetrahydrofuran and 100 parts by mass of toluene, and CTM-2 (4,4'-dimethyl- 10 parts by mass of 4″-(β-phenylstyryl)triphenylamine) was added, no polymerization initiator (Irgacure 819) was added, and an ultraviolet irradiation step using a xenon lamp after coating was performed at 120° C. for 20 minutes. Photoreceptor 15 was obtained in the same manner, except that the heating step was changed.

[Production of Photoreceptor 16]
Photoreceptor 6 was prepared in the same manner as in photoreceptor 6 except that CuAlO ₂ particles were not added to protective layer coating solution (2) and that the dispersing process using an ultrasonic homogenizer was changed to the dissolving process by stirring. got

[Production of Photoreceptor 17]
Photoreceptor 17 was prepared in the same manner as photoreceptor 16 except that the amount of copper (I) iodide (manufactured by Wako Pure Chemical Industries, Ltd.) added to protective layer coating solution (1) was changed to 10 parts by mass. Obtained.

[Production of Photoreceptor 18]
Photoreceptor 16 was produced in the same manner, except that the addition amount of SR-350 (trimethylolpropane trimethacrylate) manufactured by Sartomer Co., Ltd., which is the binder resin of protective layer coating liquid (2), was changed to 60 parts by mass. A photoreceptor 18 was obtained.

[Production of Photoreceptor 19]
In the preparation of the photoreceptor 16, copper (I) iodide (manufactured by Wako Pure Chemical Industries, Ltd.) in the protective layer coating solution (1) was changed to copper (I) bromide (manufactured by Wako Pure Chemical Industries, Ltd.). Photoreceptor 19 was obtained in the same manner.

[Production of Photoreceptor 20]
In the preparation of the photoreceptor 16, copper (I) iodide (manufactured by Wako Pure Chemical Industries, Ltd.) in the protective layer coating solution (1) was changed to copper (I) thiocyanate (manufactured by Wako Pure Chemical Industries, Ltd.). Photoreceptor 20 was obtained in the same manner.

[Production of Photoreceptor 21]
In the preparation of the photoreceptor 16, the copper (I) iodide (manufactured by Wako Pure Chemical Industries, Ltd.) in the protective layer coating liquid (1) was changed to cuprous (I) sulfide (manufactured by Mitsuwa Kagaku Co., Ltd.). , to obtain a photosensitive member 21 in the same manner.

[Production of Photoreceptor 22]
In the preparation of the photoreceptor 16, the copper (I) iodide (manufactured by Wako Pure Chemical Industries, Ltd.) in the protective layer coating liquid (1) was changed to copper (I) bromide (manufactured by Wako Pure Chemical Industries, Ltd.), and the amount added was Photoreceptor 22 was obtained in the same manner, except that the amount was changed to 20 parts by mass and 10 parts by mass of CTM-1 (4-propylbiphenyldiphenylamine) as a charge transporting substance was added to protective layer coating solution (2).
[Production of Photoreceptor 23]
In the preparation of the photoreceptor 16, the added amount of copper (I) iodide (manufactured by Wako Pure Chemical Industries, Ltd.) in the protective layer coating solution (1) was changed to 20 parts by mass, and the binder resin was SR-350 (manufactured by Sartomer Co., Ltd.). Methylolpropane trimethacrylate) was changed to polycarbonate EZ-5030 (Mitsubishi Gas Chemical Co., Ltd.), 500 parts by mass of 2-butanol was changed to a mixed solvent of 400 parts by mass of tetrahydrofuran and 100 parts by mass of toluene, and CTM was used as the charge transport material. -2 (4,4′-Dimethyl-4″-(β-phenylstyryl)triphenylamine) was added by 10 parts by mass, and a xenon lamp after coating was used without adding a polymerization initiator (Irgacure 819). Photoreceptor 23 was obtained in the same manner, except that the ultraviolet irradiation step was changed to a heating step at 120° C. for 20 minutes.

[Production of Photoreceptor 24]
Photoreceptor 1 was prepared in the same manner, except that acetonitrile in protective layer coating solution (1) was changed to 2-butanol, and the solution preparation step by mixing and stirring was changed to a dispersion step by an ultrasonic homogenizer. 24 was obtained.

[Production of Photoreceptor 25]
Photoreceptor 16 was prepared in the same manner, except that acetonitrile in protective layer coating solution (1) was changed to 2-butanol, and the solution preparation process by mixing and stirring was changed to a dispersion process by an ultrasonic homogenizer. 25 was obtained.

[Production of Photoreceptor 26]
In the preparation of the photoreceptor 24, copper (I) iodide (manufactured by Wako Pure Chemical Industries, Ltd.) in the protective layer coating solution (1) was changed to copper (I) bromide (manufactured by Wako Pure Chemical Industries, Ltd.). Photoreceptor 26 was obtained in the same manner.

[Production of Photoreceptor 27]
In the preparation of photoreceptor 1, 20 parts by mass of copper (I) iodide (manufactured by Wako Pure Chemical Industries, Ltd.) in protective layer coating liquid (1) was combined with 10 parts by mass of copper (I) iodide (manufactured by Wako Pure Chemical Industries, Ltd.). Photoreceptor 27 was obtained in the same manner, except that the mixture was changed to 10 parts by mass of copper (I) bromide (manufactured by Wako Pure Chemical Industries, Ltd.).

[Production of Photoreceptor 28]
In the preparation of the photoreceptor 16, 30 parts by mass of copper (I) iodide (manufactured by Wako Pure Chemical Industries, Ltd.) in the protective layer coating solution (1) was combined with 15 parts by mass of copper (I) iodide (manufactured by Wako Pure Chemical Industries, Ltd.). Photoreceptor 28 was obtained in the same manner, except that the mixture was changed to 15 parts by mass of copper (I) bromide (manufactured by Wako Pure Chemical Industries, Ltd.).

[Production of Photoreceptor 29]
In the preparation of the photoreceptor 16, only the protective layer coating solution (2) was used without preparing the protective layer coating solution (1). Photoreceptor 29 was obtained in the same manner, except that the amount of methylolpropane trimethacrylate) added was changed to 200 parts by mass.

[Production of Photoreceptor 30]
In the preparation of photoreceptor 1, protective layer coating solution (1) was not prepared, only protective layer coating solution (2) was used, and 80 parts by mass of CuAlO ₂ particles in protective layer coating solution (2) were replaced with silica particles (Taika Company MSN-002: average primary particle diameter 16 nm: silicone oil surface-treated product) Photoreceptor 30 was obtained in the same manner, except that the amount was changed to 100 parts by mass.

[Production of Photoreceptor 31]
In the preparation of the photoreceptor 16, only the protective layer coating solution (2) was used without preparing the protective layer coating solution (1), and 50 masses of CTM-3 (4-acryloyloxybiphenylditolylamine) was used as the charge transport material. Photoreceptor 31 was obtained in the same manner, except that 2-butanol was added and 2-butanol was changed to tetrahydrofuran.

[Production of Photoreceptor 32]
In the production of photoreceptor 1, only protective layer coating solution (2) was used without preparing protective layer coating solution (1), and 80 parts by mass of CuAlO ₂ particles in protective layer coating solution (2) was added to copper oxide (I ) Particles (EM Japan Co., Ltd.: Particles having an average primary particle diameter of 18 nm were surface-treated with a silane coupling agent KBM-503 (manufactured by Shin-Etsu Kabushiki Kaisha)) 100 parts by mass. 32 were obtained.

[Production of Photoreceptor 33]
A photoreceptor 33 was obtained in the same manner as in the preparation of photoreceptor 1, except that the manufacturing process of the charge transport layer was changed as follows and the protective layer was not formed.
<Charge transport layer>
・Charge transport layer coating solution (1)
Copper (I) iodide (manufactured by Wako Pure Chemical Industries, Ltd.): 90 parts by mass Acetonitrile: 1200 parts by mass The above components were mixed and stirred to obtain an acetonitrile solution of copper (I) iodide.
・Charge transport layer coating solution (2)
Charge transport material: CTM-2 (4,4′-dimethyl-4″-(β-phenylstyryl)triphenylamine): 135 parts by mass Antioxidant (Irganox 1010: manufactured by BASF Japan): 6 parts by mass Tetrahydrofuran: 1600 Parts by mass Toluene: 400 parts by mass Silicone oil (KF-54: manufactured by Shin-Etsu Chemical Co., Ltd.): 1 part by mass The above components were mixed and stirred to obtain a charge transport layer coating solution (2). Charge transport layer coating solution (1) was added to charge transport layer coating solution (1) to (2), and stirring was continued to prepare a charge transport layer coating solution. A 20 μm charge transport layer was formed.

[Production of Photoreceptor 34]
In the preparation of the photoreceptor 33, the amount of copper (I) iodide (manufactured by Wako Pure Chemical Industries, Ltd.) added to the charge transport layer coating solution (1) was changed to 60 parts by mass, and the charge transport substance of the charge transport layer coating solution (2) was changed to 60 parts by mass. Photoreceptor 34 was obtained in the same manner, except that the amount of (CTM-2) added was changed to 165 parts by mass.

[Production of Photoreceptor 35]
In the preparation of the photoreceptor 33, copper (I) iodide (manufactured by Wako Pure Chemical Industries, Ltd.) in the charge transport layer coating liquid (1) was changed to copper (I) bromide (manufactured by Wako Pure Chemical Industries, Ltd.). , to obtain a photosensitive member 35 in the same manner.

[Production of Photoreceptor 36]
In the preparation of the photoreceptor 33, only the charge transport layer coating solution (2) was used without preparing the charge transport layer coating solution (1), and the addition amount of the charge transport material (CTM-2) was changed to 225 parts by mass. A photosensitive member 36 was obtained in the same manner except for the above.

[Production of Photoreceptor 37]
In the preparation of the photoreceptor 33, only the charge transport layer coating solution (2) was used without preparing the charge transport layer coating solution (1). Photoreceptor 37 was obtained in the same manner, except that 60 parts by mass of the product) was added and the amount of the charge transport material (CTM-2) added was changed to 165 parts by mass.

[evaluation]
Photoreceptors 1 to 37 were mounted on a commercially available full-color multifunction machine "bizhub Press C1070" (manufactured by Konica Minolta), and evaluation was performed using electrophotographic image forming apparatuses 1 to 37.
First, an endurance test (hereinafter also referred to as “long-term printing”) was conducted in which 400,000 sheets of each A4 character image with an image ratio of 5% were printed horizontally on both sides, and a long-term printing test was performed. Afterwards, pattern memory and abrasion resistance were evaluated.

<Pattern memory>
Before and after long-term printing, in an environment with a temperature of 10° C. and a humidity of 15% RH, a solid band image in the vertical direction was transferred to a transfer material: “A3/POD gloss coat (A3 size, 100 g/m ² )” (Oji Paper Co., Ltd.). (manufactured) 20 sheets are continuously printed on the top, and then 3 sheets of solid image are printed on the entire surface. The hysteresis occurrence of band solid portions of the obtained solid image, that is, the occurrence of pattern memory (image memory) was evaluated according to the following evaluation criteria. Using a densitometer (RD-918; manufactured by Gretag Macbeth Co.), the reflection density of the area corresponding to the band solid hysteresis part and the reflection density of the area not corresponding to the band solid hysteresis part in the entire solid image obtained were measured. It was measured. Then, the two measured reflection density differences (ΔID) were calculated. Results are shown in Table I.
(Evaluation criteria)
A: ΔID of full solid is less than 0.005 (accepted)
B: ΔID of all-surface solid is 0.005 or more and less than 0.010 (accepted)
C: ΔID of 0.010 or more and less than 0.030 for all-surface solid (failed)
D: ΔID of all-surface solid is 0.030 or more (failed)

<Amount of wear>
The film thickness of the protective layer was measured before and after the durability test, and the amount of film thickness loss was calculated and evaluated. The film thickness of the protective layer is determined by randomly measuring 10 uniform film thickness portions (excluding portions where the film thickness varies at the front and rear ends of the coating) with a film thickness measuring instrument, and the average value is taken as the film thickness of the protective layer. do. An eddy-current type film thickness measuring device "EDDY560C" (manufactured by HELMUT FISCHER GMBTE CO) is used as a film thickness measuring device, and the difference in protective layer film thickness before and after the durability test is taken as the amount of film thickness loss. The amount of wear (μm) per 100 krot (100,000 rotations) is described. It should be noted that the wear amount is preferably 0.5 μm or less.

The terms used in Tables I and II above are as follows.
AN: acetonitrile BN: butyronitrile Et ₂ S: diethylsulfide 2-BuOH: 2-butanol THF: tetrahydrofuran Tol: toluene

As is clear from the results shown in Tables I and II above, when the photoreceptor of the present invention is used, image memory does not occur and abrasion resistance is excellent as compared to the case of using the photoreceptor of the comparative example. I know there is.

1Y, 1M, 1C, 1Bk Photoreceptor drums 2Y, 2M, 2C, 2Bk Charging means 3Y, 3M, 3C, 3Bk Image exposing means 4Y, 4M, 4C, 4Bk Developing means 6Y, 6M, 6C, 6Bk Cleaning means 10Y, 10M , 10C, 10Bk image forming unit

Claims (7)

An electrophotographic photoreceptor in which a charge generation layer, a charge transport layer and a protective layer are laminated in this order on a conductive support,
The protective layer contains at least one copper compound selected from copper (I) iodide, copper (I) bromide, copper (I) thiocyanate and copper (I) sulfide, and
The electrophotographic photosensitive material, wherein the content (parts by mass) of the copper compound in the entire protective layer is at least twice the content (parts by mass) of the charge transport agent made of an organic compound in the entire protective layer. body. 2. The electrophotographic photoreceptor according to claim 1 , wherein the protective layer contains a resin obtained by photopolymerizing and curing a crosslinkable polymerizable compound. 3. The electrophotographic photoreceptor according to claim 1 , wherein the protective layer contains fine oxide particles that are p-type semiconductors. An electrophotographic image forming method, comprising using the electrophotographic photoreceptor according to any one of claims 1 to 3 . An electrophotographic image forming apparatus comprising the electrophotographic photoreceptor according to any one of claims 1 to 3 . A method for producing an electrophotographic photoreceptor for producing the electrophotographic photoreceptor according to any one of claims 1 to 3 ,
At least one of copper(I) iodide, copper(I) bromide, copper(I) thiocyanate and copper(I) sulfide is dissolved in an organic solvent in forming the protective layer of the electrophotographic photoreceptor. A method for producing an electrophotographic photoreceptor, comprising: 7. The production of an electrophotographic photoreceptor according to claim 6 , further comprising a step of irradiating a protective layer coating liquid containing a crosslinkable polymerizable compound with actinic rays to polymerize and cure the protective layer to form the protective layer. Method.

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