JP2012247749A - Image forming apparatus, image forming method and process cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus and others, capable of suppressing adhesion of hydrophobic silica particles on a photoreceptor and forming an image of high picture quality with good resolution.SOLUTION: The image forming apparatus includes: an electrophotographic photoreceptor, which has a photosensitive layer and a surface protective layer containing at least two kinds of metal oxide particles on a support; charging means; exposure means; developing means for developing an electrostatic latent image by using a toner including externally added silica particles that have been subjected to a hydrophobicity imparting treatment, to form a visible image; transfer means; and cleaning means. In the surface protective layer, the average thickness D (μm) of the layer, a particle diameter d1 (μm) of metal oxide particles having the largest particle diameter in the at least two kinds of metal oxide particles, and a particle diameter d2 (μm) of metal oxide particles having the smallest particle diameter satisfy d1≥D/5 and d1≥8×d2. The cleaning means includes a cleaning blade and a cleaning brush, in which the cleaning brush is disposed downstream the cleaning blade along a rotation direction of the electrophotographic photoreceptor.

Description

  The present invention relates to an image forming apparatus, an image forming method, and a process cartridge applied to a copying machine, a facsimile, a laser printer, a direct digital plate making machine, and the like.

  An electrophotographic image forming apparatus is applied to a copying machine, a laser printer, and the like. As an electrophotographic photosensitive member (hereinafter also referred to as a “photosensitive member”) used therefor, selenium and zinc oxide are used. Since the days when inorganic photoconductors such as cadmium sulfide have been mainstream, organic photoconductors (OPCs) are now more advantageous than inorganic photoconductors because of their reduced environmental impact, lower costs, and higher design freedom. ) Is widely used.

  Such organic photoreceptors can be classified by layer structure, for example, (1) a photoconductive resin represented by polyvinylcarbazole (PVK), PVK-TNF (2,4,7-trinitrofluorenone) A homogeneous single layer type in which a charge transfer complex represented by the above is provided on a conductive support, (2) a dispersed single layer type in which a pigment such as phthalocyanine or perylene is dispersed in a resin is provided on the conductive support; (3) The photosensitive layer provided on the conductive support is divided into a charge generation layer (CGL) containing a charge generation material such as an azo pigment and a charge transport layer (CTL) containing a charge transport material such as triphenylamine. It can be categorized into functionally separated stacked types.

In the case of the layered type (3), there are a structure in which a charge transport layer is provided on a charge generation layer and a structure opposite to this structure, the former being common and the latter being particularly called a reverse layer.
In particular, the multilayer type is advantageous for high sensitivity and, in addition, there is a high degree of freedom in design for high sensitivity and high durability. It is taken.
In recent years, the importance of manufacturing in consideration of global environmental conservation has increased, and electrophotographic photoreceptors are required to be converted from supply products (disposable consumables) as mechanical parts.
For this purpose, it is necessary to extend the life of the electrophotographic photosensitive member. As a countermeasure, particularly in the case of an organic photosensitive member, a surface layer is formed on the photosensitive layer with a protective layer having excellent wear resistance. It is becoming common.

In addition, toners used in electrophotography are advantageous in improving the reduction of the global environmental load during toner production, low power consumption due to low-temperature fixing, and high image quality, so polymerized toner, spherical toner, and small particle size toner The use of (generally, 6 μm or less) is becoming mainstream.
On the other hand, the toner remaining on the photoconductor after the transfer process is scraped by bringing the edge of the cleaning blade made of an elastic material such as rubber into pressure contact with the photoconductor surface in a direction opposite to the rotation direction, so-called counter direction. It is widely known that it is configured to drop.
In terms of removing toner from the photoreceptor, it becomes more difficult as the toner particle size becomes smaller. In particular, in the case of cleaning with a cleaning blade, the edge tends to slip through as the toner particle size becomes smaller.

As a toner for solving these problems, there is a method for improving cleaning properties by externally adding silica particles hydrophobized to the surface of the toner base particles to reduce the adhesion between the photoreceptor and the toner. It has been proposed (see Patent Document 1).
In addition, as the cleaning blade, a rubber strip shape (sheet shape) cut into a width of 1 mm to 5 mm having a specific rubber characteristic such as rebound resilience and rubber hardness (JIS-A hardness), aluminum, The thing attached to the plate-shaped support base made from iron is proposed (refer patent documents 2-4).

Although these techniques improve the cleaning properties of the toner, when the silica particles added to the toner are detached and separated from the toner and adhere to the surface of the photoreceptor, the adhered particles have a very small particle size. With conventional cleaning means, cleaning becomes difficult, and there is a problem that so-called filming occurs, which remains on the surface of the photoreceptor and is fixed by the pressure of the blade and frictional heat.
In particular, when a surface protective layer is provided on the photoconductor, it becomes more difficult to remove the photoconductor due to a decrease in the amount of wear of the photoconductor. It has a problem that it adheres to the body on the body and leads to the generation of abnormal images in which the deposits appear in the image. There is a need for an image forming apparatus that combines suppression.

As another means for improving the cleaning ability, there is a method using a cleaning means using a cleaning blade and a cleaning brush in combination (see Patent Documents 5 to 10).
In the case of a cleaning means using both a cleaning blade and a cleaning brush, the cleaning brush has a function of forcibly removing foreign matters that are difficult to remove with the cleaning blade, but it is located upstream of the cleaning blade with respect to the photosensitive member rotation direction. In a configuration equipped with a cleaning brush, a large amount of residual toner enters the cleaning brush, so that the cleaning brush becomes dirty with repeated use over a short period of time, and the cleaning performance cannot be maintained over a long period of time. Was not enough.

Further, as another means for improving the cleaning ability using the cleaning brush, a cleaning auxiliary means is used in combination with the upstream side of the cleaning brush with respect to the rotation direction of the photosensitive member, and the fibrous body or the plate-like member is photosensitive as the cleaning auxiliary means. There is a method of cleaning by contacting the body (see Patent Documents 11 and 12).
However, these methods also have a large contact area between the cleaning auxiliary means and the photoconductor, so that the toner contamination of the auxiliary means becomes particularly noticeable due to repeated use, and the cleaning function of the auxiliary means is reduced accordingly. There is a problem in that the toner cannot be sufficiently removed with a brush and an abnormal image is generated.

Furthermore, as another means for improving the cleaning capability using a cleaning brush, for example, a method using a cleaning means using a cleaning brush and a polishing apparatus in combination has been proposed (see Patent Documents 13 to 14). These proposed methods are methods for removing the deposits on the photoconductor by scraping the outermost surface of the photoconductor, and are useful when used in combination with a photoconductor having a surface protective layer excellent in wear resistance. An effect is obtained.
However, the removal member containing these abrasive particles is excellent in the removability when the silica particles added to the toner adhere to the photoconductor, but has a surface asperity, so the removability of the residual toner Becomes lower. As a result, there are problems such as the occurrence of slipping of the toner, causing an abnormal image, and the toner mixing into the removal member containing the abrasive particles and further adhering to reduce the polishing effect. is there.

  An object of the present invention is to solve the above-described problems and achieve the following objects. That is, the present invention uses an electrophotographic photosensitive member having high wear resistance and high durability, and suppresses adhesion to the photosensitive member caused by the action of hydrophobic silica particles used as an external additive of the toner. An object of the present invention is to provide an image forming apparatus, an image forming method, and a process cartridge capable of forming a high image quality.

Means for solving the problems are as follows. That is,
<1> An electrophotographic photosensitive member having a photosensitive layer and a surface protective layer containing at least two kinds of metal oxide particles on a support;
Charging means for charging the surface of the electrophotographic photosensitive member;
Exposure means for exposing the charged electrophotographic photosensitive member surface to form an electrostatic latent image; and
Developing means for developing the electrostatic latent image using a toner to which silica particles subjected to hydrophobic treatment are externally added to form a visible image;
Transfer means for transferring the visible image to a recording medium;
Cleaning means for removing toner and silica particles remaining on the electrophotographic photosensitive member,
The average thickness D (μm) of the surface protective layer in the electrophotographic photosensitive member, the particle diameter d1 (μm) of the metal oxide particle having the largest particle diameter among at least two kinds of metal oxide particles, and the largest particle diameter The particle size d2 (μm) of the small metal oxide particles satisfies the following formulas, d1 ≧ D / 5, and d1 ≧ 8 × d2,
The image forming apparatus according to claim 1, wherein the cleaning unit includes a cleaning blade and a cleaning brush, and the cleaning brush is disposed downstream of the cleaning blade in the rotation direction of the electrophotographic photosensitive member.
<2> a charging step for charging the surface of an electrophotographic photosensitive member having a photosensitive layer and a surface protective layer containing at least two kinds of metal oxide particles on a support;
Exposing the charged electrophotographic photoreceptor surface to form an electrostatic latent image; and
A developing step of developing the electrostatic latent image using a toner to which silica particles subjected to a hydrophobic treatment are externally added to form a visible image;
A transfer step of transferring the visible image to a recording medium;
A cleaning step of removing toner and silica particles remaining on the electrophotographic photosensitive member,
The average thickness D (μm) of the surface protective layer in the electrophotographic photosensitive member, the particle diameter d1 (μm) of the metal oxide particle having the largest particle diameter among at least two kinds of metal oxide particles, and the largest particle diameter The particle size d2 (μm) of the small metal oxide particles satisfies the following formulas, d1 ≧ D / 5, and d1 ≧ 8 × d2,
In the image forming method, the cleaning step is performed using a cleaning blade and a cleaning brush, and the cleaning brush is disposed downstream of the cleaning blade in the rotation direction of the electrophotographic photosensitive member. is there.
<3> an electrophotographic photosensitive member having a photosensitive layer and a surface protective layer containing at least two kinds of metal oxide particles on a support;
Developing means for developing a visible image by developing with toner having externally added silica particles hydrophobized;
A process cartridge having at least cleaning means for removing toner and silica particles remaining on the electrophotographic photosensitive member,
The average thickness D (μm) of the surface protective layer in the electrophotographic photosensitive member, the particle diameter d1 (μm) of the metal oxide particle having the largest particle diameter among at least two kinds of metal oxide particles, and the largest particle diameter The particle size d2 (μm) of the small metal oxide particles satisfies the following formulas, d1 ≧ D / 5, and d1 ≧ 8 × d2,
The process cartridge is characterized in that the cleaning means has a cleaning blade and a cleaning brush, and the cleaning brush is disposed downstream of the cleaning blade in the rotation direction of the electrophotographic photosensitive member.

  According to the present invention, various conventional problems can be solved, and a photosensitive member produced by the action of hydrophobic silica particles used as an external additive of a toner using an electrophotographic photosensitive member having high wear resistance and high durability. Thus, it is possible to provide an image forming apparatus, an image forming method, and a process cartridge that can prevent adhesion to the toner and maintain high image quality with good resolution.

FIG. 1 is a schematic cross-sectional view of an electrophotographic photosensitive member having a surface protective layer used in the image forming apparatus of the present invention. FIG. 2 is a schematic view showing the configuration of the cleaning means in an example of the image forming apparatus of the present invention. FIG. 3 is a schematic diagram for explaining an example of the image forming apparatus of the present invention. FIG. 4 is a schematic view showing an example of the process cartridge of the present invention.

(Image forming apparatus and image forming method)
The image forming apparatus of the present invention includes an electrophotographic photosensitive member, a charging unit, an exposure unit, a developing unit, a transfer unit, and a cleaning unit, and other units appropriately selected as necessary, for example, , Fixing means, static elimination means, recycling means, control means, and the like. The charging unit and the exposure unit may be collectively referred to as an electrostatic latent image forming unit.
The electrophotographic photoreceptor has a photosensitive layer and a surface protective layer containing at least two kinds of metal oxide particles on a support.
The image forming method of the present invention includes a charging step, an exposure step, a development step, a transfer step, and a cleaning step, and other steps appropriately selected as necessary, for example, a fixing step, a charge removal step, and a recycling step. A process, a control process, and the like. The charging process and the exposure process may be collectively referred to as an electrostatic latent image forming process.

  The image forming method of the present invention can be preferably carried out by the image forming apparatus of the present invention, the charging step can be performed by the charging unit, the exposure step can be performed by the exposing unit, The developing step can be performed by the developing unit, the transferring step can be performed by the transferring unit, the cleaning step can be performed by the cleaning unit, and the fixing step can be performed by the fixing unit. The other steps can be performed by the other means.

<Electrophotographic photoreceptor>
The electrophotographic photoreceptor has a support, a photosensitive layer on the support, and a surface protective layer containing at least two kinds of metal oxide particles, and further includes other layers as necessary. It becomes.

  The layer structure of the electrophotographic photoreceptor of the present invention is not particularly limited and can be appropriately selected depending on the purpose. The support and a photosensitive layer (charge generation layer, charge generation layer, A charge transport layer) and a surface protective layer in this order, and may have an undercoat layer as necessary, and the surface protective layer is the outermost surface. In addition, a mode in which a photosensitive layer having a single layer structure mainly composed of a charge generating substance and a charge transporting substance on a support and a surface protective layer on the photosensitive layer may be used.

Here, FIG. 1 is a schematic cross-sectional view showing an example of an electrophotographic photosensitive member provided with a surface protective layer excellent in abrasion resistance used in the present invention.
The electrophotographic photosensitive member shown in FIG. 1 has a photosensitive layer 22 provided on a support 21 and a surface protective layer 28 having excellent wear resistance on the outermost surface. The photosensitive layer 22 is a charge generation layer. 25 and a charge transport layer 26, and a subbing layer 24 is provided between the support 21 and the photosensitive layer 22. The undercoat layer 24 may not be provided.

<< surface protective layer >>
The average thickness D (μm) of the surface protective layer in the electrophotographic photosensitive member, the particle size d1 (μm) of one type of metal oxide particles having the largest particle size among at least two types of metal oxide particles, and the largest The particle size d2 (μm) of the metal oxide particles having a small particle size satisfies the following expressions, d1 ≧ D / 5, and d1 ≧ 8 × d2. This makes it possible to achieve both high durability and cleanability.
That is, the average thickness D of the surface protective layer, the particle size d1 (μm) of the metal oxide particles having the largest particle size among the at least two types of metal oxide particles, and the particles of the metal oxide particles having the smallest particle size Although it is not certain as a factor that an excellent effect can be obtained when the diameter d2 (μm) shows a specific relationship, a metal having a certain particle diameter with respect to the average thickness D of the surface protective layer By including oxide particles in the surface protective layer, it becomes possible to give irregularities to the surface shape, and as a result, a fine nip is formed between the photoconductor and the cleaning blade, so that the silica particles released from the toner Can be prevented from adhering to the photoreceptor due to pressing at the nip portion of the cleaning blade. In addition, by incorporating metal oxide particles having a certain particle size or less in the surface protective layer, it is possible to improve the hardness and mechanical strength of the entire surface protective layer without affecting the surface shape. Thus, silica particles are present in the concave portions of the surface shape of the photoconductor, and it is possible to suppress the adhesion of silica particles even when strongly pressed by the cleaning blade.
The average thickness D (μm) of the surface protective layer, the particle size d1 (μm) of the metal oxide particle having the largest particle size among the at least two kinds of metal oxide particles, and the metal oxide particle having the smallest particle size If the particle diameter d2 (μm) of the toner satisfies d1 <D / 5, the surface shape of the photoreceptor is likely to be smooth, and silica particles released from the toner are pressed by the nip portion of the cleaning blade and adhere to the photoreceptor. It becomes easy. Further, when d1 <8 × d2, the surface shape of the photoconductor is likely to be smooth, silica particles are likely to adhere to the photoconductor as described above, or the surface roughness of the photoconductor becomes very large, The toner may not be removed and an abnormal image may easily occur.
The average thickness D of the surface protective layer is preferably 0.8 μm to 1.5 μm. If the average thickness D is less than 0.8 μm, the surface irregularities of the photoreceptor may become too large to remove the toner and silica particles, and if it exceeds 1.5 μm, the surface shape of the photoreceptor may be It may become smooth and the silica particles may easily adhere to the photoreceptor.
The average thickness D of the surface protective layer can be measured by, for example, an eddy current film thickness meter (Fisherscope MMS, manufactured by Fisher Instruments Co., Ltd.).

The surface of the photoreceptor is such that the ten-point average roughness Rz (μm) of the surface of the electrophotographic photoreceptor and the average thickness D (μm) of the surface protective layer satisfy the following formula: Rz ≧ D / 2 It is preferable in that it is possible to suppress the pressing of the silica particles released from the toner against the photoreceptor by forming irregularities. When the ten-point average roughness Rz (μm) of the surface of the electrophotographic photosensitive member and the average thickness D (μm) of the surface protective layer are Rz <D / 2, the surface shape of the photosensitive member becomes smooth. The silica particles may easily adhere to the photoreceptor.
The ten-point average roughness Rz of the surface of the electrophotographic photosensitive member is preferably 0.5 μm to 1.5 μm, and more preferably 0.6 μm to 1.0 μm. When the ten-point average roughness Rz is less than 0.5 μm, silica particles may easily adhere to the photoconductor, and when it exceeds 1.5 μm, the surface irregularities of the photoconductor become too large, and the toner In some cases, silica particles cannot be removed.
The ten-point average roughness Rz can be measured based on the surface roughness standard JIS B 0601: 2001, for example, using a surface roughness measuring machine (Surfcom 1400D, manufactured by Tokyo Seimitsu Co., Ltd.).

Examples of the metal oxide particles contained in the surface protective layer include titanium oxide, silica, tin oxide, alumina, zirconium oxide, indium oxide, calcium oxide, and zinc oxide.
Among these, as the metal oxide having the smallest particle size, it is preferable to use a conductive metal oxide because it exhibits excellent electrical characteristics. Examples of the conductive metal oxide include tin oxide, zinc oxide, and indium oxide.
Of the two or more kinds of metal oxide particles contained in the surface protective layer, the particle diameter of the metal oxide particles having the largest particle diameter is preferably 0.2 μm to 0.5 μm in terms of primary average particle diameter. The metal oxide particles having the smallest particle diameter are preferably 5 nm to 60 nm in terms of primary average particle diameter.
The primary average particle diameter is calculated by, for example, the average value of the long axis and short axis of the metal oxide particles observed with a scanning electron microscope (SEM), and the average value of 10 metal oxide particles is derived. Can be sought.

The metal oxide particles may be surface-treated with an inorganic material or an organic material for reasons such as improving dispersibility.
Examples of the organic treatment include those treated with a silane coupling agent, those treated with a fluorine-based silane coupling agent, and those treated with a higher fatty acid.
Examples of the inorganic treatment include those obtained by treating a metal oxide surface with alumina, zirconia, tin oxide, or silica.
The metal oxide particles are pulverized and dispersed, and then mixed with the surface protective layer coating solution for coating.

The content of the metal oxide fine particles is preferably 3 parts by mass to 60 parts by mass, and more preferably 5 parts by mass to 50 parts by mass with respect to 100 parts by mass of the total component of the surface protective layer. If the content is less than 3 parts by mass, the wear resistance is not sufficient, but if it exceeds 60 parts by mass, the transparency of the photosensitive layer may be impaired.
Further, the contained mass A of the metal oxide particles having the largest particle size among the two or more types of metal oxide particles in the surface protective layer is larger than the contained mass B of the metal oxide particles having the smallest particle size. Is preferable in terms of improving the surface shape and the strength of the entire film. It is preferable that the content mass A is twice or more the content mass B.

  The surface protective layer is preferably formed by polymerizing at least a polymerizable compound. From the viewpoint of mechanical durability, a polymerizable compound having three or more polymerizable functional groups in the molecule is preferably used. That is, by polymerizing a polymerizable compound having three or more functional groups, a three-dimensional network structure is developed, and a surface protection layer having a very high crosslink density and a high elasticity is obtained, and has high wear resistance and scratch resistance. Is achieved.

There is no restriction | limiting in particular as a kind of curable resin, According to the objective, it can select suitably, For example, an amino resin, a urethane resin, an epoxy resin, a phenol resin, a silicone resin, an acrylic resin etc. are mentioned. Among these, a UV curable acrylic resin containing a tri- or higher functional radical polymerizable monomer is particularly preferable from the viewpoint of wear resistance.
Examples of the tri- or higher functional radical polymerizable monomer include trimethylolpropane triacrylate (TMPTA), trimethylolpropane trimethacrylate, trimethylolpropane alkylene-modified triacrylate, trimethylolpropane ethyleneoxy-modified (hereinafter EO-modified) triacrylate. , Trimethylolpropane propyleneoxy modified (hereinafter PO modified) triacrylate, trimethylolpropane caprolactone modified triacrylate, trimethylolpropane alkylene modified trimethacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate (PETTA), glycerol triacrylate, glycerol epi Chlorohydrin modified (hereinafter ECH modified) triacrylate, grease Roll EO modified triacrylate, glycerol PO modified triacrylate, tris (acryloxyethyl) isocyanurate, dipentaerythritol hexaacrylate (DPHA), dipentaerythritol caprolactone modified hexaacrylate, dipentaerythritol hydroxypentaacrylate, alkylated dipentaerythritol Pentaacrylate, alkylated dipentaerythritol tetraacrylate, alkylated dipentaerythritol triacrylate, dimethylolpropane tetraacrylate (DTMPTA), pentaerythritol ethoxytetraacrylate, phosphoric acid EO-modified triacrylate, 2,2,5,5,- Examples thereof include tetrahydroxymethylcyclopentanone tetraacrylate. These may be used individually by 1 type and may use 2 or more types together.

In the formation of the surface protective layer, in addition to the polymerizable compound, a charge transporting compound (with or without a polymerizable functional group does not matter, but from the viewpoint of mechanical durability, those having a polymerizable functional group are preferred. Can be used). The charge transporting compound having a polymerizable functional group preferably has a smaller number of functional groups from the viewpoint of distortion of the cured resin structure and internal stress of the surface protective layer, and a monofunctional charge transporting compound can be used favorably.
Examples of the dispersion solvent that can be used as the coating solvent for the surface protective layer include ketones, ethers, aromatic compounds, halogen compounds, and esters.
Among these, methyl ethyl ketone, tetrahydrofuran, and cyclohexanone are particularly preferable because they have a lower environmental impact than chlorobenzene, dichloromethane, toluene, and xylene.

In the present invention, a polymerization initiator may be contained as required in order to allow the curing reaction to proceed efficiently. Examples of the polymerization initiator include a thermal polymerization initiator and a photopolymerization initiator.
Examples of the thermal polymerization initiator include 2,5-dimethylhexane-2,5-dihydroperoxide, dicumyl peroxide, benzoyl peroxide, t-butylcumyl peroxide, 2,5-dimethyl-2,5. -Di (peroxybenzoyl) hexyne-3, di-t-butyl peroxide, t-butyl hydroperoxide, cumene hydroperoxide, lauroyl peroxide, 2,2-bis (4,4-di-t-butyl Peroxycyclohexyl) propane and other peroxide initiators; azobisisobutylnitrile, azobiscyclohexanecarbonitrile, methyl azobisisobutyrate, azobisisobutylamidine hydrochloride, 4,4′-azobis-4-cyanovaleric acid, etc. And azo initiators.

Examples of the photopolymerization initiator include diethoxyacetophenone, 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, and 4- (2-hydroxyethoxy) phenyl. -(2-hydroxy-2-propyl) ketone, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) butanone-1,2-hydroxy-2-methyl-1-phenylpropan-1-one Acetophenone-based or ketal-based photopolymerization of 2-methyl-2-morpholino (4-methylthiophenyl) propan-1-one, 1-phenyl-1,2-propanedione-2- (o-ethoxycarbonyl) oxime, etc. Agents: benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isobuty Benzoin ether photopolymerization initiators such as ether and benzoin isopropyl ether; benzophenone, 4-hydroxybenzophenone, methyl o-benzoylbenzoate, 2-benzoylnaphthalene, 4-benzoylbiphenyl, 4-benzoylphenyl ether, acrylated benzophenone, 1 Benzophenone photopolymerization initiators such as 1,4-benzoylbenzene; thioxanthone photopolymerization such as 2-isopropylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2,4-dichlorothioxanthone An initiator etc. are mentioned.
Examples of other photopolymerization initiators include ethyl anthraquinone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylethoxyphosphine oxide, and bis (2,4,6-trimethylbenzoyl). Phenylphosphine oxide, bis (2,4-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, methylphenylglyoxyester, 9,10-phenanthrene, acridine compounds, triazine compounds, imidazole compounds, etc. Can be mentioned. These may be used individually by 1 type and may use 2 or more types together.

Moreover, what has a photopolymerization acceleration effect can also be used individually or in combination with the said photoinitiator. Examples include triethanolamine, methyldiethanolamine, ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, (2-dimethylamino) ethyl benzoate, 4,4′-dimethylaminobenzophenone, and the like.
The content of the polymerization initiator is preferably 0.1 part by mass to 40 parts by mass, and more preferably 0.5 part by mass to 20 parts by mass with respect to 100 parts by mass of the total compound having a polymerizable functional group.

Moreover, low molecular compounds, such as antioxidant, a plasticizer, a lubricant, and an ultraviolet absorber, and a leveling agent can also be added as needed. These compounds can be used individually by 1 type or in mixture of 2 or more types.
The amount of the low-molecular compound used is preferably 0.1 to 50 parts by mass, more preferably 0.1 to 20 parts by mass with respect to 100 parts by mass of the resin component. As for the usage-amount of the said leveling agent, 0.001 mass part-5 mass parts are preferable with respect to 100 mass parts of resin components.

Examples of the method for forming the surface protective layer include an immersion method, a spray coating method, a ring coating method, a roll coater method, a gravure coating method, a nozzle coating method, a screen printing method, and the like. And a method of forming a surface protective layer.
The external energy used at this time includes heat, light, radiation, etc., and is selected depending on the resin used.
The heat energy is applied by heating from the coating surface side or the support side using a gas such as air, nitrogen, steam, various heat media, infrared rays, or electromagnetic waves.
The heating temperature is preferably 100 ° C. or higher and 170 ° C. or lower. When the heating temperature is less than 100 ° C., the reaction rate is slow and the curing reaction may not be completed completely. When the heating temperature is higher than 170 ° C., the curing reaction proceeds non-uniformly and causes large distortion in the surface protective layer. Many unreacted residues and reaction termination ends may occur.
In order to advance the curing reaction uniformly, it is also effective to complete the reaction by heating at a relatively low temperature of less than 100 ° C. and then heating to 100 ° C. or more.

As the energy of light, UV irradiation light sources such as high pressure mercury lamps and metal halide lamps, which mainly have an emission wavelength in ultraviolet light, can be used. Is possible.
The amount of irradiation light is preferably 50 mW / cm ² or more and 1,000 mW / cm ² or less. The irradiation dose is less than 50 mW / cm ^2, it may take time for the curing reaction, exceeds 1,000 mW / cm ^2, the progress of the reaction becomes uneven, localized wrinkles in the protective layer surface May occur, or many unreacted residues and reaction termination ends may occur.
In addition, internal stress increases due to rapid crosslinking, which causes cracks and film peeling. Examples of radiation energy include those using electron beams.
Among these energies, those using heat and light energy are useful because of the ease of reaction rate control and the simplicity of the apparatus.

<< Photosensitive layer >>
As the photosensitive layer, a laminated photosensitive layer in which a charge generation layer and a charge transport layer are sequentially laminated is preferable.

-Charge generation layer-
The charge generation layer refers to a part of the laminated photosensitive layer, has a function of generating charges upon exposure, contains a charge generation material as a main component, and optionally contains a binder resin.

-Charge generation material-
As the charge generation material, inorganic materials and organic materials can be used.
The inorganic material is not particularly limited and may be appropriately selected depending on the intended purpose. For example, crystalline selenium, amorphous selenium, selenium-tellurium, selenium-tellurium-halogen, selenium-arsenic compound, amorphous silicon Etc.
As the amorphous silicon, for example, dangling bonds terminated with hydrogen atoms or halogen atoms, those doped with boron atoms, phosphorus atoms or the like are preferably used.

The organic material is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include metal phthalocyanines such as titanyl phthalocyanine and chlorogallium phthalocyanine; metal-free phthalocyanines, azurenium salt pigments, squaric methine pigments, Symmetric or asymmetric azo pigments having a carbazole skeleton, symmetric or asymmetric azo pigments having a triphenylamine skeleton, symmetric or asymmetric azo pigments having a diphenylamine skeleton, symmetric or asymmetric having a dibenzothiophene skeleton Type azo pigments, symmetric or asymmetric azo pigments having a fluorenone skeleton, symmetric or asymmetric azo pigments having an oxadiazole skeleton, symmetric or asymmetric azo pigments having a bisstilbene skeleton, distil Symmetric or asymmetric azo pigments having an oxadiazole skeleton, symmetric or asymmetric azo pigments having a distyrylcarbazole skeleton, perylene pigments, anthraquinone or polycyclic quinone pigments, quinoneimine pigments, diphenylmethane and triphenyl Examples thereof include phenylmethane pigments, benzoquinone and naphthoquinone pigments, cyanine and azomethine pigments, indigoid pigments, and bisbenzimidazole pigments. These may be used individually by 1 type and may use 2 or more types together.
Among these, metal phthalocyanines, symmetric or asymmetric azo pigments having a fluorenone skeleton, symmetric or asymmetric azo pigments having a triphenylamine skeleton, and perylene pigments are particularly preferable in terms of high charge generation quantum efficiency. .

--Binder resin--
The binder resin used as necessary for the charge generation layer is not particularly limited and can be appropriately selected depending on the purpose. For example, polyamide, polyurethane, epoxy resin, polyketone, polycarbonate, polyarylate, silicone resin , Acrylic resin, polyvinyl butyral, polyvinyl formal, polyvinyl ketone, polystyrene, poly-N-vinylcarbazole, polyacrylamide and the like. These may be used individually by 1 type and may use 2 or more types together. Among these, polyvinyl butyral is particularly preferable.

The method for forming the charge generation layer is roughly divided into a vacuum thin film preparation method and a casting method from a solution dispersion system.
Examples of the former method include a vacuum deposition method, a glow discharge decomposition method, an ion plating method, a sputtering method, a reactive sputtering method, a CVD (chemical vapor deposition) method, and the like from the above-described inorganic or organic materials. Can be formed satisfactorily.
In order to provide the charge generation layer by the casting method, the above-described inorganic or organic charge generation material may be ball milled, attritored using a solvent such as tetrahydrofuran, cyclohexanone, dioxane, dichloroethane, butanone together with a binder resin if necessary. What is necessary is just to disperse | distribute by a sand mill etc. and apply | coat after diluting a dispersion liquid moderately.
Among these, methyl ethyl ketone, tetrahydrofuran, and cyclohexanone are particularly preferable because they have a lower environmental impact than chlorobenzene, dichloromethane, toluene, and xylene.
The coating can be performed by, for example, a dip coating method, a spray coating method, a bead coating method, or the like.
The thickness of the charge generation layer is preferably 0.01 μm to 5 μm, more preferably 0.05 μm to 2 μm.

-Charge transport layer-
The charge transport layer is a layer that constitutes a part of the laminated photosensitive layer that functions to inject and transport charges generated in the charge generation layer and to neutralize the surface charge of the photoreceptor provided by charging.

The charge transport layer contains a charge transport material and a binder component, and further contains other components as necessary.
The charge transport layer can be formed by dissolving or dispersing a mixture or copolymer mainly composed of a charge transport component and a binder component in an appropriate solvent, and applying and drying the mixture.
Examples of the coating method include a dipping method, a spray coating method, a ring coating method, a roll coater method, a gravure coating method, a nozzle coating method, and a screen printing method.
The thickness of the charge transport layer is preferably 15 μm to 40 μm, more preferably 15 μm to 30 μm, and 15 μm to 25 μm when resolving power is required for practically necessary sensitivity and chargeability. Is particularly preferred.
Since a protective layer is laminated on the charge transport layer, the thickness of the charge transport layer in this configuration does not need to be designed to increase the thickness of the charge transport layer in consideration of film scraping in actual use. Also, thinning is possible.
Examples of the dispersion solvent that can be used in preparing the charge transport layer coating solution include ketones such as methyl ethyl ketone, acetone, methyl isobutyl ketone, and cyclohexanone; ethers such as dioxane, tetrahydrofuran, and ethyl cellosolve; toluene, xylene, and the like Aromatics; halogens such as chlorobenzene and dichloromethane; and esters such as ethyl acetate and butyl acetate. These may be used individually by 1 type and may use 2 or more types together.
Among these, methyl ethyl ketone, tetrahydrofuran, and cyclohexanone are preferable because they have a lower environmental impact than chlorobenzene, dichloromethane, toluene, and xylene.

--Binder component--
The polymer compound that can be used as the binder component of the charge transport layer is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include polystyrene, styrene-acrylonitrile copolymer, and styrene-butadiene. Copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyvinylidene chloride, polyarylate, polycarbonate, cellulose acetate, ethyl cellulose, polyvinyl butyral , Polyvinyl formal, polyvinyl toluene, acrylic resin, silicone resin, fluororesin, epoxy resin, melamine resin, urethane resin, phenol resin, alkyd resin, and the like.
These polymer compounds can be used singly or as a mixture of two or more kinds, or as a copolymer comprising two or more of these raw material monomers, and further copolymerized with a charge transport material.
Among these, polystyrene, polyester, polyarylate, and polycarbonate are useful because many of them have good charge transfer characteristics when used as a binder component of a charge transport component.
Since the charge transport layer has a surface protective layer laminated thereon, the charge transport layer is not required to have mechanical strength as compared with the conventional charge transport layer.
For this reason, a material such as polystyrene, which is highly transparent but has a low mechanical strength and is difficult to apply in the prior art, can be effectively used as the binder component of the charge transport layer.

-Charge transport material-
Examples of the charge transport material include a hole transport material and an electron transport material.
Examples of the electron transporting material include chloroanil, bromoanil, tetracyanoethylene, tetracyanoquinodimethane, 2,4,7-trinitro-9-fluorenone, 2,4,5,7-tetranitro-9-fluorenone, 2 , 4,5,7-tetranitroxanthone, 2,4,8-trinitrothioxanthone, 2,6,8-trinitro-4H-indeno [1,2-b] thiophen-4-one, 1,3,7 -Electron accepting materials such as trinitrodibenzothiophene-5,5-dioxide and benzoquinone derivatives.
Examples of the hole transport material include poly-N-vinylcarbazole or a derivative thereof, poly-γ-galvazolylethyl glutamate or a derivative thereof, pyrene-formaldehyde condensate or a derivative thereof, polyvinylpyrene, polyvinylphenanthrene, polysilane, Oxazole derivatives, oxadiazole derivatives, imidazole derivatives, monoarylamine derivatives, diarylamine derivatives, triarylamine derivatives, stilbene derivatives, α-phenylstilbene derivatives, benzidine derivatives, diarylmethane derivatives, triarylmethane derivatives, 9-styrylanthracene Derivatives, pyrazoline derivatives, divinylbenzene derivatives, hydrazine derivatives, indene derivatives, butadiene derivatives, pyrene derivatives, bisstilbene derivatives, enamine derivatives Etc.
These charge transport materials may be used alone or in combination of two or more.

If necessary, the charge transport layer may contain a low-molecular compound such as an antioxidant, a plasticizer, a lubricant, and an ultraviolet absorber and a leveling agent. These compounds can be used alone or as a mixture of two or more.
When a low molecular weight compound and a leveling agent are used in combination, sensitivity deterioration may occur.
For this reason, 0.1 mass part-20 mass parts are preferable with respect to 100 mass parts of resin contained in the said charge transport layer, and, as for the usage-amount of the said low molecular compound, 0.1 mass part-10 mass parts are more. preferable. The amount of the leveling agent used is preferably 0.001 to 0.1 parts by mass.

<< Support >>
The support is not particularly limited as long as it has a volume resistance of 10 ¹⁰ Ω · cm or less, and can be appropriately selected according to the purpose. For example, aluminum, nickel, chromium, nichrome, Metals such as copper, gold, silver, and platinum; metal oxides such as tin oxide and indium oxide deposited on film or cylindrical plastic, paper, or aluminum or aluminum alloy by vapor deposition or sputtering. A plate made of nickel, stainless steel or the like and a tube subjected to surface treatment such as cutting, super-finishing, polishing, or the like after being formed into a raw pipe by a method such as extruding and drawing out can be used. Further, an endless nickel belt and an endless stainless steel belt disclosed in JP-A-52-36016 can also be used as a support.

Moreover, what coated and disperse | distributed conductive powder to the appropriate binder resin on the said support body can also be used as a support body.
Examples of the conductive powder include carbon black, acetylene black; metal powder such as aluminum, nickel, iron, nichrome, copper, zinc, and silver; metal oxide powder such as conductive tin oxide and ITO. It is done. Examples of the binder resin used at the same time include polystyrene resin, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester resin, polyvinyl chloride resin, vinyl chloride- Vinyl acetate copolymer, polyvinyl acetate resin, polyvinylidene chloride resin, polyarylate resin, phenoxy resin, polycarbonate resin, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral resin, polyvinyl formal resin, polyvinyl toluene resin, poly-N-vinyl Examples thereof include carbazole, acrylic resin, silicone resin, epoxy resin, melamine resin, urethane resin, phenol resin, and alkyd resin. These may be used individually by 1 type and may use 2 or more types together.
The conductive layer can be provided by dispersing and applying these conductive powder and binder resin in a suitable solvent such as tetrahydrofuran, dichloromethane, methyl ethyl ketone, toluene and the like.

  Further, heat shrinkage of the conductive powder contained in a material such as polyvinyl chloride, polypropylene, polyester, polystyrene, polyvinylidene chloride, polyethylene, chlorinated rubber, Teflon (registered trademark) on a suitable cylindrical substrate. What provided the electroconductive layer with the tube can also be used suitably as a support body.

-Undercoat layer-
The electrophotographic photosensitive member used in the image forming apparatus of the present invention may be provided with an undercoat layer between the support and the photosensitive layer as necessary.
The undercoat layer is generally composed of a resin as a main component. However, considering that the resin is coated on the photosensitive layer using a solvent, the resin is resistant to dissolution with a general organic solvent. A high resin is preferable.
The resin is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include water-soluble resins such as polyvinyl alcohol, casein and sodium polyacrylate; alcohol-soluble resins such as copolymer nylon and methoxymethylated nylon. Resins; Examples thereof include curable resins that form a three-dimensional network structure such as polyurethane, melamine resin, alkyd resin, melamine resin, and epoxy resin.
In addition, by adding fine powders such as metal oxides exemplified by titanium oxide, silica, alumina, zirconium oxide, tin oxide, indium oxide, etc., or metal sulfides, metal nitrides, etc. as fillers in the undercoat layer, Furthermore, stable chargeability can be maintained.
The undercoat layer can be formed using a suitable solvent and coating method.
The thickness of the undercoat layer is preferably 10 μm or less, and more preferably 0.2 μm to 6 μm.

  In the electrophotographic photoreceptor, an intermediate layer may be provided on the support, if necessary. The intermediate layer contains a resin as a main component, and these resins are preferably resins having a high solvent resistance with respect to an organic solvent in consideration of applying a photosensitive layer thereon with a solvent. As the resin, the same resin as the undercoat layer can be appropriately selected and used.

  In the electrophotographic photosensitive member, in order to improve environmental resistance, in particular, in order to prevent a decrease in sensitivity and an increase in residual potential, each layer such as a charge generation layer, a charge transport layer, an undercoat layer, and a surface protective layer is provided. Antioxidants, plasticizers, lubricants, ultraviolet absorbers, low molecular charge transport materials, leveling agents and the like can be added.

<Charging step and charging means>
The charging step is a step of charging the surface of the electrophotographic photosensitive member, and is performed by a charging unit.
The charging can be performed, for example, by applying a voltage to the surface of the electrophotographic photosensitive member using the charger.
The charger is not particularly limited and may be appropriately selected depending on the purpose. For example, a known contact charging device including a conductive or semiconductive roller, brush, film, rubber blade, etc. And non-contact chargers using corona discharge such as corotrons and corotrons.
The charging member may take any form such as a magnetic brush or a fur brush in addition to the roller, and can be selected according to the specifications and form of the electrophotographic image forming apparatus. In the case of using a magnetic brush, the magnetic brush is composed of, for example, various ferrite particles such as Zn-Cu ferrite as a charging member, and a non-magnetic conductive sleeve for supporting the same, and a magnet roll included therein. . Or when using a brush, for example, as the material of the fur brush, a fur treated with carbon, copper sulfide, metal or metal oxide is used, and this is wound around a metal or other conductive core. Make it a charger by sticking.
The charger is not limited to the contact charger as described above, but has an advantage that an image forming apparatus in which ozone generated from the charger is reduced can be obtained.
It is preferable that the charger is arranged in contact or non-contact with the electrophotographic photosensitive member and charges the surface of the electrophotographic photosensitive member by applying DC and AC voltages in a superimposed manner.
Further, the charger is a charging roller having a gap tape on the electrophotographic photosensitive member and arranged in a non-contact manner, and the surface of the electrophotographic photosensitive member is charged by applying a direct current and an alternating voltage to the charging roller. Those are also preferred.

<Exposure process and exposure means>
The exposure step is a step of exposing the charged electrophotographic photosensitive member surface, and is performed by the exposure means.
The exposure can be performed, for example, by exposing the surface of the electrophotographic photosensitive member imagewise using the exposure unit.
The optical system in the exposure is roughly classified into an analog optical system and a digital optical system. The analog optical system is an optical system that projects a document directly onto an electrophotographic photosensitive member by an optical system, and the digital optical system receives image information as an electrical signal, converts it into an optical signal, and converts it into an electrophotographic image. It is an optical system that exposes a photoreceptor and forms an image.
The exposure unit is not particularly limited as long as the surface of the electrophotographic photosensitive member charged by the charging unit can be exposed like an image to be formed, and can be appropriately selected according to the purpose. However, various exposure devices such as a copying optical system, a rod lens array system, a laser optical system, a liquid crystal shutter optical system, and an LED optical system can be used.
In the present invention, an optical backside system that performs imagewise exposure from the backside of the electrophotographic photosensitive member may be employed.

<Development process and development means>
The developing step is a step of developing the electrostatic latent image using toner or developer to form a visible image, and is performed by a developing unit.
The visible image can be formed, for example, by developing the electrostatic latent image using the toner or the developer, and can be performed by the developing unit.
The developing means is not particularly limited as long as it can be developed using, for example, the toner or the developer, and can be appropriately selected from known ones. For example, the toner or developer is accommodated. Preferred examples include those having at least a developing unit capable of bringing the toner or developer into contact or non-contact with the electrostatic latent image.

  The developing unit may be a dry developing type, a wet developing type, a single color developing unit, or a multi-color developing unit. For example, a toner having a stirrer for charging the toner or the developer by frictional stirring and a rotatable magnet roller is preferable.

  In the developing device, for example, the toner and the carrier are mixed and agitated, and the toner is charged by friction at that time, and held on the surface of the rotating magnet roller in a raised state to form a magnetic brush. . Since the magnet roller is disposed in the vicinity of the electrophotographic photosensitive member, a part of the toner constituting the magnetic brush formed on the surface of the magnet roller is electrically attracted to the electrophotographic photosensitive member. Move to the surface of the body. As a result, the electrostatic latent image is developed with the toner, and a visible image is formed with the toner on the surface of the electrophotographic photosensitive member.

  The developer accommodated in the developing device is a developer containing the toner, but the developer may be a one-component developer or a two-component developer.

<< Toner >>
As a toner suitably used in the image forming apparatus of the present invention, at least one type of hydrophobized silica particles is externally added to the surface of toner base particles.
The toner base particles can be kneaded and pulverized by melting and kneading a resin, pigment, charge control agent, and release agent, cooling and then pulverizing and classifying, but the particle size and shape are uniform. Therefore, it is more preferable to use those prepared by using a polymerization toner method such as an emulsion polymerization method or a dissolution suspension method.

  Hereinafter, as an example, a constituent material and a production method of a polyester polymerization toner will be specifically described.

-Polyester resin-
The polyester resin is obtained by a polycondensation reaction between a polyhydric alcohol compound and a polycarboxylic acid compound.

  Examples of the polyhydric alcohol compound (PO) include dihydric alcohol (DIO) and trihydric or higher polyhydric alcohol (TO). (DIO) alone or a mixture of (DIO) and a small amount of (TO). Is preferred.

Examples of the dihydric alcohol (DIO) include alkylene glycol (for example, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, etc.), Alkylene ether glycol (eg, diethylene glycol, triethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol, etc.), alicyclic diol (eg, 1,4-cyclohexanedimethanol, hydrogenated bisphenol A, etc.) ), Bisphenols (for example, bisphenol A, bisphenol F, bisphenol S, etc.), alkylene oxides of the above alicyclic diols (for example, ethylene oxide, propylene oxide). Side, butylene oxide, etc.) adducts, alkylene oxide of the bisphenols (e.g., ethylene oxide, propylene oxide, and the like butylene oxide, etc.) adducts.
Among these, alkylene glycols having 2 to 12 carbon atoms and alkylene oxide adducts of bisphenols are preferable, and the combination of alkylene oxide adducts of bisphenols and alkylene glycols having 2 to 12 carbon atoms is particularly preferable.

  The trihydric or higher polyhydric alcohol (TO) is a trihydric or higher polyhydric aliphatic alcohol (for example, glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, sorbitol, etc.), trihydric or higher. Phenols (for example, trisphenol PA, phenol novolak, cresol novolak, etc.), and alkylene oxide adducts of the above trivalent or higher polyphenols.

Examples of the polyvalent carboxylic acid (PC) include divalent carboxylic acid (DIC) and trivalent or higher polyvalent carboxylic acid (TC). (DIC) alone, (DIC) and a small amount of (TC) Is preferred.
Examples of the divalent carboxylic acid (DIC) include alkylene dicarboxylic acids (eg, succinic acid, adipic acid, sebacic acid, etc.), alkenylene dicarboxylic acids (eg, maleic acid, fumaric acid, etc.), aromatic dicarboxylic acids (eg, phthalic acid). Acid, isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid, etc.). Among these, alkenylene dicarboxylic acid having 4 to 20 carbon atoms and aromatic dicarboxylic acid having 8 to 20 carbon atoms are particularly preferable.
Examples of the trivalent or higher polyvalent carboxylic acid (TC) include aromatic polycarboxylic acids having 9 to 20 carbon atoms (such as trimellitic acid and pyromellitic acid).
In addition, as polyhydric carboxylic acid (PC), you may make it react with polyhydric alcohol (PO) using the acid anhydride or lower alkyl ester (For example, methyl ester, ethyl ester, isopropyl ester, etc.) of the above-mentioned thing. .

The ratio between the polyhydric alcohol (PO) and the polyhydric carboxylic acid (PC) is 2/1 to 1/1 as the equivalent ratio [OH] / [COOH] of the hydroxyl group [OH] and the carboxyl group [COOH]. Preferably, 1.5 / 1 to 1/1 is more preferable, and 1.3 / 1 to 1.02 / 1 is still more preferable.
The polycondensation reaction between the polyhydric alcohol (PO) and the polyvalent carboxylic acid (PC) is heated to 150-280 ° C. in the presence of a known esterification catalyst such as tetrabutoxy titanate, dibutyltin oxide, etc. The produced water is distilled off under reduced pressure to obtain a polyester having a hydroxyl group.

The hydroxyl value of the polyester resin is preferably 5 mgKOH / g or more, and the acid value of the polyester resin is preferably 1 mgKOH / g to 30 mgKOH / g, more preferably 5 mgKOH / g to 25 mgKOH / g. By giving an acid value, the toner tends to be negatively charged, and further, when fixing to a recording paper, the affinity between the recording paper and the toner is good and the low-temperature fixing property is improved. However, when the acid value exceeds 30 mgKOH / g, there is a tendency to deteriorate with respect to the stability of charging, particularly environmental fluctuation.
The polyester resin has a weight average molecular weight of preferably 10,000 to 400,000, more preferably 20,000 to 200,000. When the weight average molecular weight is less than 10,000, the offset resistance may be deteriorated, and when it exceeds 400,000, the low-temperature fixability may be deteriorated.

  The polyester resin preferably contains a urea-modified polyester resin in addition to the unmodified polyester resin obtained by the polycondensation reaction. The urea-modified polyester resin is a polyester prepolymer (A) having an isocyanate group by reacting a terminal carboxyl group, a hydroxyl group, and the like of the polyester resin obtained by the polycondensation reaction with a polyvalent isocyanate compound (PIC), This is obtained by cross-linking and / or extending the molecular chain by the reaction of amines.

  Examples of the polyvalent isocyanate compound (PIC) include aliphatic polyisocyanates (for example, tetramethylene diisocyanate, hexamethylene diisocyanate, 2,6-diisocyanatomethyl caproate), alicyclic polyisocyanates (for example, isophorone). Diisocyanate, cyclohexylmethane diisocyanate, etc.), aromatic diisocyanate (eg, tolylene diisocyanate, diphenylmethane diisocyanate, etc.), araliphatic diisocyanate (eg, α, α, α ′, α′-tetramethylxylylene diisocyanate, etc.), isocyanates , Those obtained by blocking the polyisocyanate with a phenol derivative, oxime, caprolactam or the like, or a combination of two or more thereof.

The ratio of the polyvalent isocyanate compound (PIC) is usually 5/1 to 1/1, preferably as an equivalent ratio [NCO] / [OH] of the isocyanate group [NCO] and the hydroxyl group [OH] of the polyester having a hydroxyl group. Is 4/1 to 1.2 / 1, more preferably 2.5 / 1 to 1.5 / 1. When the equivalent ratio [NCO] / [OH] exceeds 5, the low-temperature fixability may be deteriorated. When the equivalent of [NCO] is less than 1, when a urea-modified polyester is used, the urea content in the ester is lowered, and the hot offset resistance may be deteriorated.
The content of the polyvalent isocyanate compound (PIC) component in the polyester prepolymer (A) having an isocyanate group is preferably 0.5% by mass to 40% by mass, more preferably 1% by mass to 30% by mass. More preferably, the content is 20% by mass to 20% by mass. When the content is less than 0.5% by mass, the hot offset resistance is deteriorated, which may be disadvantageous in terms of both heat-resistant storage stability and low-temperature fixability, and when it exceeds 40% by mass, Low temperature fixability may deteriorate.

  The number of isocyanate groups contained per molecule in the polyester prepolymer (A) having an isocyanate group is preferably 1 or more, preferably 1.5 to 3 on average, more preferably 1.8 to 2 on average. Five. When the number is less than 1 per molecule, the molecular weight of the urea-modified polyester is lowered, and the hot offset resistance may be deteriorated.

Next, as amines (B) to be reacted with the polyester prepolymer (A), a divalent amine compound (B1), a trivalent or higher polyvalent amine compound (B2), an amino alcohol (B3), an amino mercaptan (B4) ), Amino acid (B5), amino acid block of B1 to B5 (B6), and the like.
Examples of the divalent amine compound (B1) include aromatic diamines (eg, phenylenediamine, diethyltoluenediamine, 4,4′-diaminodiphenylmethane), and alicyclic diamines (eg, 4,4′-diamino-). 3,3′-dimethyldicyclohexylmethane, diaminecyclohexane, isophoronediamine, etc.), aliphatic diamines (eg, ethylenediamine, tetramethylenediamine, hexamethylenediamine, etc.) and the like. Examples of the trivalent or higher polyvalent amine compound (B2) include diethylenetriamine and triethylenetetramine.
Examples of the amino alcohol (B3) include ethanolamine and hydroxyethylaniline.
Examples of the amino mercaptan (B4) include aminoethyl mercaptan and aminopropyl mercaptan.
Examples of the amino acid (B5) include aminopropionic acid and aminocaproic acid. Examples of B1 to B5 blocked amino groups (B6) include ketimine compounds and oxazolidine compounds obtained from the amines of B1 to B5 and ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.). Among these amines (B), preferred are B1 and a mixture of B1 and a small amount of B2.
The ratio of the amines (B) is equivalent to the equivalent ratio [NCO] / [NHx of the isocyanate group [NCO] in the polyester prepolymer (A) having an isocyanate group and the amino group [NHx] in the amine (B). ] Is usually 1/2 to 2/1, preferably 1.5 / 1 to 1 / 1.5, more preferably 1.2 / 1 to 1 / 1.2. When [NCO] / [NHx] exceeds 2 or less than 1/2, the molecular weight of the urea-modified polyester is lowered, and the hot offset resistance may be deteriorated.
The urea-modified polyester may contain a urethane bond together with a urea bond. The molar ratio between the urea bond content and the urethane bond content is preferably 100/0 to 10/90, more preferably 80/20 to 20/80, and still more preferably 60/40 to 30/70. When the molar ratio of the urea bond is less than 10%, the hot offset resistance may be deteriorated.

  The urea-modified polyester is produced by a one-shot method or the like. Water produced by heating polyhydric alcohol (PO) and polyhydric carboxylic acid (PC) to 150 to 280 ° C. in the presence of a known esterification catalyst such as tetrabutoxy titanate or dibutyltin oxide, and if necessary, reducing the pressure. Is distilled off to obtain a polyester having a hydroxyl group. Next, at 40 ° C. to 140 ° C., polyisocyanate (PIC) is reacted with this to obtain a polyester prepolymer (A) having an isocyanate group. Further, this (A) is reacted with amines (B) at 0 ° C. to 140 ° C. to obtain a urea-modified polyester.

When reacting (PIC) and (A) and (B), a solvent may be used as necessary. For example, aromatic solvents (eg, toluene, xylene, etc.), ketones (eg, acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.), esters (eg, ethyl acetate, etc.); amides (eg, dimethylformamide, dimethylacetamide, etc.) ), Ethers (for example, tetrahydrofuran, etc.) and the like, an inert solvent for isocyanate (PIC) can be used.
In addition, in the crosslinking and / or extension reaction between the polyester prepolymer (A) and the amines (B), a reaction terminator can be used as necessary to adjust the molecular weight of the resulting urea-modified polyester. Examples of the reaction terminator include monoamines (eg, diethylamine, dibutylamine, butylamine, laurylamine, etc.), or those obtained by blocking them (eg, ketimine compounds).

The weight average molecular weight of the urea-modified polyester resin is preferably 10,000 or more, more preferably 20,000 to 10,000,000, and still more preferably 30,000 to 1,000,000. When the weight average molecular weight is less than 10,000, the hot offset resistance may be deteriorated. The number average molecular weight of the urea-modified polyester or the like is not particularly limited when the above-mentioned unmodified polyester resin is used, and may be a number average molecular weight that can be easily obtained to obtain the weight average molecular weight.
When the urea-modified polyester resin is used alone, the number average molecular weight is preferably 2,000 to 15,000, more preferably 2,000 to 10,000, and further preferably 2,000 to 8,000. . When the number average molecular weight exceeds 15,000, low temperature fixability and gloss when used in a full color apparatus may be deteriorated.

The use of the unmodified polyester resin and the urea-modified polyester resin in combination improves the low-temperature fixability and gloss when used in a full-color image forming apparatus, and is therefore preferable to using a urea-modified polyester resin alone. . The unmodified polyester resin may include polyester modified with a chemical bond other than a urea bond.
The unmodified polyester resin and the urea-modified polyester resin are preferably at least partially compatible with each other in terms of low-temperature fixability and hot offset resistance. Accordingly, it is preferable that the unmodified polyester resin and the urea-modified polyester resin have similar compositions.
The mass ratio of the unmodified polyester resin and the urea-modified polyester resin is preferably 20/80 to 95/5, more preferably 70/30 to 95/5, and still more preferably 75/25 to 95/5. 80/20 to 93/7 is particularly preferable. When the mass ratio of the urea-modified polyester resin is less than 5%, the hot offset resistance is deteriorated, and it may be disadvantageous in terms of both heat-resistant storage stability and low-temperature fixability.
The glass transition temperature (Tg) of the binder resin containing the unmodified polyester resin and the urea-modified polyester resin is preferably 45 ° C to 65 ° C, and more preferably 45 ° C to 60 ° C. When the glass transition temperature is less than 45 ° C., the heat resistance of the toner may be deteriorated, and when it exceeds 65 ° C., the low-temperature fixability may be insufficient.
Further, the urea-modified polyester resin tends to be present on the surface of the obtained toner base particles, and therefore, the heat-resistant storage stability tends to be good even when the glass transition temperature is low as compared with known polyester-based toners.

<Colorant>
The colorant is not particularly limited, and all known dyes and pigments can be used. For example, carbon black, nigrosine dye, iron black, naphthol yellow S, Hansa yellow (10G, 5G, G), cadmium yellow , Yellow iron oxide, ocher, yellow lead, titanium yellow, polyazo yellow, oil yellow, Hansa yellow (GR, A, RN, R), pigment yellow L, benzidine yellow (G, GR), permanent yellow (NCG), Vulcan Fast Yellow (5G, R), Tartrazine Lake, Quinoline Yellow Lake, Anthrazan Yellow BGL, Isoindolinone Yellow, Bengala, Red Dan, Lead Zhu, Cadmium Red, Cadmium Mercury Red, Antimon Zhu, Permanent Red 4R, Para Red, Faisa Red, Lachlor Ortho Nitroaniline Red, Resol Fast Scarlet G, Brilliant Fast Scarlet, Brilliant Carmine BS, Permanent Red (F2R, F4R, FRL, FRLL, F4RH), Fast Scarlet VD, Belkan Fast Rubin B, Brilliant Scarlet G, Resol Rubin GX Permanent Red F5R, Brilliant Carmine 6B, Pigment Scarlet 3B, Bordeaux 5B, Tolujing Maroon, Permanent Bordeaux F2K, Helio Bordeaux BL, Bordeaux 10B, Bon Maroon Light, Bon Maroon Medium, Eosin Lake, Rhodamine Lake B, Rhodamine Lake Y, Alizarin Lake, Thioindigo Red B, Thioindigo Maroon, Oil Red, Quinacridone , Pyrazolone red, polyazo red, chrome vermilion, benzidine orange, perinone orange, oil orange, cobalt blue, cerulean blue, alkali blue rake, peacock blue rake, Victoria blue rake, metal free phthalocyanine blue, phthalocyanine blue, fast sky blue, Indanthrene blue (RS, BC), indigo, ultramarine, bitumen, anthraquinone blue, fast violet B, methyl violet lake, cobalt violet, manganese purple, dioxane violet, anthraquinone violet, chrome green, zinc green, chromium oxide, pyridian, Emerald Green, Pigment Green B, Naphthol Green B, Green Gold, Acid Green Lake, Malachite Examples include green lake, phthalocyanine green, anthraquinone green, titanium oxide, zinc white, and ritbon. These may be used individually by 1 type and may use 2 or more types together.

The content of the colorant is preferably 1% by mass to 15% by mass and more preferably 3% by mass to 10% by mass with respect to the toner.
The colorant can also be used as a master batch combined with a resin.
As a binder resin to be kneaded with the production of the master batch or the master batch, a polymer of styrene such as polystyrene, poly-p-chlorostyrene, polyvinyltoluene or the like, or a copolymer of these and a vinyl compound; Polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, epoxy resin, epoxy polyol resin, polyurethane, polyamide, polyvinyl butyral, polyacrylic acid resin, rosin, modified rosin, terpene resin, fat Aromatic or alicyclic hydrocarbon resin, aromatic petroleum resin, chlorinated paraffin, paraffin wax and the like. These may be used individually by 1 type and may use 2 or more types together.

<Charge control agent>
There is no restriction | limiting in particular as said charge control agent, All can use a well-known thing. For example, nigrosine dyes, triphenylmethane dyes, chromium-containing metal complex dyes, molybdate chelate pigments, rhodamine dyes, alkoxy amines, quaternary ammonium salts (including fluorine-modified quaternary ammonium salts), alkylamides, phosphorus Simple substance or compound, tungsten simple substance or compound, fluorine-based activator, salicylic acid metal salt, salicylic acid derivative metal salt, and the like.
Specifically, Bontron 03 of nigrosine dye, Bontron P-51 of quaternary ammonium salt, Bontron S-34 of metal-containing azo dye, E-82 of oxynaphthoic acid metal complex, E- of salicylic acid metal complex 84, E-89 of phenol-based condensate (above, manufactured by Orient Chemical Co., Ltd.), TP-302, TP-415 of quaternary ammonium salt molybdenum complex (made of Hodogaya Chemical Co., Ltd.), quaternary ammonium salt Copy charge PSY VP2038, copy blue PR of triphenylmethane derivative, copy charge of quaternary ammonium salt NEG VP2036, copy charge NX VP434 (manufactured by Hoechst), LRA-901, LR-147 which is a boron complex (Nippon Carlit) , Copper phthalocyanine, perylene, quinacridone, azo Examples thereof include pigments and other polymer compounds having functional groups such as sulfonic acid groups, carboxyl groups, and quaternary ammonium salts. These may be used individually by 1 type and may use 2 or more types together. Among these, a substance that controls the negative polarity of the toner is particularly preferable.
The content of the charge control agent is determined by the toner production method including the type of binder resin, the presence or absence of additives used as necessary, and the dispersion method, and is not uniquely limited. However, 0.1 mass part-10 mass parts are preferable with respect to 100 mass parts of said binder resins, and 0.2 mass part-5 mass parts are more preferable. When the content exceeds 10 parts by mass, the chargeability of the toner is too high, the effect of the charge control agent is reduced, the electrostatic attraction with the developing roller is increased, the developer fluidity is reduced, and the image The concentration may decrease.

<Release agent>
As the release agent, a low melting point wax having a melting point of 50 ° C. to 120 ° C. works more effectively as a release agent in the dispersion with the binder resin between the fixing roller and the toner interface. Effective against high temperature offset without applying release agent such as oil to fixing roller.
As such waxes, waxes and waxes include plant waxes such as carnauba wax, cotton wax, wood wax, rice wax, animal waxes such as beeswax and lanolin, and mineral waxes such as ozokerite and cercin; Examples include petroleum waxes such as paraffin, microcrystalline, and petrolatum.
In addition to these natural waxes, synthetic hydrocarbon waxes such as Fischer-Tropsch wax and polyethylene wax; synthetic waxes such as esters, ketones, and ethers can be used.
Further, fatty acid amides such as 12-hydroxystearic acid amide, stearic acid amide, phthalic anhydride imide, chlorinated hydrocarbon, and low molecular weight crystalline polymer resin, poly-n-stearyl methacrylate, poly-n- A homopolymer or copolymer of polyacrylate such as lauryl methacrylate (for example, a copolymer of n-stearyl acrylate-ethyl methacrylate, etc.), a crystalline polymer having a long alkyl group in the side chain, or the like can also be applied.
The charge control agent and the release agent may be melt-kneaded together with the master batch and the binder resin, or may be added when dissolved and dispersed in an organic solvent.

-External additive-
As at least one of the external additives, hydrophobized silica particles (hydrophobic silica particles) are used.
The hydrophobic silica particles mean particles that can be surface treated to increase hydrophobicity and prevent deterioration of flow characteristics and charging characteristics even under high humidity. Examples of the surface treatment agent include a silane coupling agent, a silylating agent, a silane coupling agent having a fluorinated alkyl group, an organic titanate coupling agent, an aluminum coupling agent, silicone oil, a modified silicone oil, Etc.
The primary average particle diameter of the hydrophobic silica particles is preferably 100 nm to 200 nm. If the primary average particle size is less than 100 nm, the toner cleaning properties may deteriorate and streaky abnormal images may be generated. If the primary average particle size exceeds 200 nm, the toner flow characteristics and charging characteristics are deteriorated, resulting in scumming. Etc. may occur.
Here, the primary average particle diameter of the hydrophobic silica particles is obtained by measuring the diameters of 50 particles from an observation image using an electrophotographic microscope such as a scanning electron microscope (SEM) or a transmission electron microscope (TEM). It can be obtained by deriving an average value.

The hydrophobicity of the hydrophobic silica particles is preferably 50% to 90%, more preferably 60% to 80%. When the degree of hydrophobicity is less than 50%, toner charge leakage under high temperature and high humidity increases, and toner scattering and photoreceptor fogging are likely to occur. On the other hand, if the degree of hydrophobicity exceeds 90%, the toner tends to be excessively charged under low temperature and low humidity, and image density defects may occur. In addition, the presence of excess hydrophobizing agent may adversely affect the fluidity of the toner.
Here, the method for measuring the degree of hydrophobicity is as follows.
Place 50 mL of water in a 200 mL beaker and add another 0.2 g of hydrophobic silica particles. Then, while gently stirring with a magnetic stirrer, methanol was added from the burette where the tip was immersed in water at the time of dropping, and the floating hydrophobic silica particles began to sink. Read and calculate from the following formula.
Hydrophobicity (%) = (mL of methanol dropped / (50 + mL of methanol dropped)) × 100

In addition to the hydrophobic silica particles, other external additives may be used in combination. Examples of inorganic fine particles include silica, alumina, titania, barium titanate, magnesium titanate, calcium titanate, and titanic acid. Strontium, zinc oxide, tin oxide, silica sand, clay, mica, wollastonite, diatomaceous earth, chromium oxide, cerium oxide, bengara, antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, carbonized Examples thereof include silicon and silicon nitride.
The content of the external additive in the toner is preferably 0.01% by mass to 5.0% by mass, and more preferably 0.01% by mass to 2.0% by mass.

-Other ingredients-
There is no restriction | limiting in particular as said other component, According to the objective, it can select suitably, For example, a fluidity improver, a cleaning property improver, a magnetic material, a metal soap, etc. are mentioned.

<Manufacturing method>
Next, a toner manufacturing method will be described. In the following, specific examples will be shown, and the toner manufacturing method applied to the present invention is not limited to the following.
(A) A toner material solution is prepared by dispersing a colorant, unmodified polyester, a polyester prepolymer having an isocyanate group, and a release agent in an organic solvent.
The organic solvent is preferably volatile with a boiling point of less than 100 ° C. from the viewpoint of easy removal after toner base particle formation. Specifically, toluene, xylene, benzene, carbon tetrachloride, methylene chloride, 1,2-dichloroethane, 1,1,2-trichloroethane, trichloroethylene, chloroform, monochlorobenzene, dichloroethylidene, methyl acetate, ethyl acetate, methyl ethyl ketone, And methyl isobutyl ketone. These can be used alone or in combination of two or more. Among these, aromatic solvents such as toluene and xylene, and halogenated hydrocarbons such as methylene chloride, 1,2-dichloroethane, chloroform, and carbon tetrachloride are particularly preferable.
300 mass parts or less are preferable with respect to 100 mass parts of polyester prepolymers, and, as for the usage-amount of the said organic solvent, 100 mass parts or less are more preferable, and 25 mass parts-70 mass parts are still more preferable.

(B) The toner material liquid is emulsified in an aqueous medium in the presence of a surfactant and resin fine particles.
The aqueous medium may be water alone, alcohol (eg, methanol, isopropyl alcohol, ethylene glycol, etc.), dimethylformamide, tetrahydrofuran, cellosolves (eg, methyl cellosolve), lower ketones (eg, acetone, methyl ethyl ketone). Etc.) may be included.
The amount of the aqueous medium used with respect to 100 parts by mass of the toner material liquid is preferably 50 parts by mass to 2,000 parts by mass, and more preferably 100 parts by mass to 1,000 parts by mass. When the amount used is less than 50 parts by mass, the dispersion state of the toner material liquid is poor, and toner particles having a predetermined particle diameter may not be obtained.

Further, in order to improve the dispersion in the aqueous medium, a dispersant such as a surfactant and resin fine particles is appropriately added.
Examples of the surfactant include anionic surfactants such as alkylbenzene sulfonates, α-olefin sulfonates and phosphates; amine salts such as alkylamine salts, aminoalcohol fatty acid derivatives, polyamine fatty acid derivatives, and imidazolines. Type: quaternary ammonium salt type cationic surfactant such as alkyltrimethylammonium salt, dialkyldimethylammonium salt, alkyldimethylbenzylammonium salt, pyridinium salt, alkylisoquinolinium salt, benzethonium chloride, fatty acid amide derivative, Amphoteric surfactants such as nonionic surfactants such as dihydric alcohol derivatives such as alanine, dodecyldi (aminoethyl) glycine, di (octylaminoethyl) glycine, N-alkyl-N, N-dimethylammonium betaine Agents.

Moreover, the effect can be exhibited in a very small amount by using a surfactant having a fluoroalkyl group. Suitable anionic surfactants having a fluoroalkyl group include fluoroalkylcarboxylic acids having 2 to 10 carbon atoms or metal salts thereof, disodium perfluorooctanesulfonyl glutamate, 3- [ω-fluoroalkyl (C6 to C11). Oxy] -1-alkyl (C3-C4) sodium sulfonate, 3- [ω-fluoroalkanoyl (C6-C8) -N-ethylamino] -1-propanesulfonic acid sodium, fluoroalkyl (C11-C20) carboxylic acid Or metal salt, perfluoroalkylcarboxylic acid (C7 to C13) or metal salt thereof, perfluoroalkyl (C4 to C12) sulfonic acid or metal salt thereof, perfluorooctanesulfonic acid diethanolamide, N-propyl-N- (2 -Hydroxyethyl) perfluorooctane Sulfonamide, perfluoroalkyl (C6-C10) sulfonamidopropyltrimethylammonium salt, perfluoroalkyl (C6-C10) -N-ethylsulfonylglycine salt, monoperfluoroalkyl (C6-C16) ethyl phosphate, etc. .
As a trade name, for example, Surflon S-111, S-112, S-113 (Asahi Glass Co., Ltd.), Florard FC-93, FC-95, FC-98, FC-129 (Sumitomo 3M Co., Ltd.), Unidyne DS -101, DS-102 (manufactured by Daikin Industries, Ltd.), Megafac F-110, F-120, F-113, F-191, F-812, F-833 (manufactured by Dainippon Ink & Chemicals, Inc.), Xtop EF-102, 103, 104, 105, 112, 123A, 123B, 306A, 501, 201, 204 (manufactured by Tochem Products), and Fgentent F-100, F150 (manufactured by Neos).

Examples of the cationic surfactant include aliphatic primary, secondary or tertiary amine acids having a fluoroalkyl group, and aliphatic quaternary ammonium salts such as perfluoroalkyl (C6-C10) sulfonamidopropyltrimethylammonium salt, Benzalkonium salt, benzethonium chloride, pyridinium salt, imidazolinium salt, trade names include Surflon S-121 (Asahi Glass Co.), Florard FC-135 (Sumitomo 3M), Unidyne DS-202 (Daikin Industries) ), Megafuck F-150, F-824 (Dainippon Ink Chemical Co., Ltd.), Xtop EF-132 (Tochem Products), Footgent F-300 (Neos), and the like.
The resin fine particles are added to stabilize the toner base particles formed in the aqueous medium. For this reason, it is preferable to add so that the coverage existing on the surface of the toner base particles is in the range of 10% to 90%.
For example, polymethyl methacrylate fine particles 1 μm and 3 μm, polystyrene fine particles 0.5 μm and 2 μm, poly (styrene-acrylonitrile) fine particles 1 μm, trade names are PB-200H (manufactured by Kao), SGP (manufactured by Soken), Technopolymer Examples thereof include SB (manufactured by Sekisui Chemical Co., Ltd.), SGP-3G (manufactured by Sokensha), and micropearl (manufactured by Sekisui Fine Chemical Co., Ltd.).
In addition, inorganic compound dispersants such as tricalcium phosphate, calcium carbonate, titanium oxide, colloidal silica, and hydroxyapatite can also be used.

  As a dispersant that can be used in combination with the resin fine particles and the inorganic compound dispersant, the dispersed droplets may be stabilized by a polymeric protective colloid. For example, acids such as acrylic acid, methacrylic acid, α-cyanoacrylic acid, α-cyanomethacrylic acid, itaconic acid, crotonic acid, fumaric acid, maleic acid or maleic anhydride; (meth) acrylic monomer containing hydroxyl group (For example, acrylic acid-β-hydroxyethyl, methacrylic acid-β-hydroxyethyl, acrylic acid-β-hydroxypropyl, methacrylic acid-β-hydroxypropyl, acrylic acid-γ-hydroxypropyl, methacrylic acid-γ- Hydroxypropyl, 3-chloro-2-hydroxypropyl acrylate, 3-chloro-2-hydroxypropyl methacrylate, diethylene glycol monoacrylate, diethylene glycol monomethacrylate, glycerol monoacrylate, glycerol monomethacrylate , N-methylol acrylamide, N-methylol methacrylamide, etc.); vinyl alcohol or ethers with vinyl alcohol (for example, vinyl methyl ether, vinyl ethyl ether, vinyl propyl ether, etc.); compounds containing vinyl alcohol and a carboxyl group Esters (eg, vinyl acetate, vinyl propionate, vinyl butyrate, etc.); acrylamide, methacrylamide, diacetone acrylamide, or their methylol compounds, acid chlorides such as acrylic acid chloride, methacrylic acid chloride; vinyl pyridine, vinyl Nitrogen-containing compounds such as pyrrolidone, vinylimidazole, and ethyleneimine; or homopolymers or copolymers such as those having a heterocyclic ring thereof; polyoxyethylene, polyoxypropylene, polyoxy Ethylene alkylamine, polyoxypropylene alkylamine, polyoxyethylene alkylamide, polyoxypropylene alkylamide, polyoxyethylene nonyl phenyl ether, polyoxyethylene lauryl phenyl ether, polyoxyethylene stearyl phenyl ester, polyoxyethylene nonyl phenyl ester, etc. Polyoxyethylene-based; and celluloses such as methylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, and the like.

  The dispersion method is not particularly limited and may be appropriately selected depending on the intended purpose. For example, any of known methods such as a low-speed shear method, a high-speed shear method, a friction method, a high-pressure jet method, and an ultrasonic wave can be applied. . Among these, the high-speed shearing method is preferable in order to make the particle size of the dispersion 2 μm to 20 μm. When a high-speed shearing disperser is used, the number of rotations is not particularly limited, but is preferably 1,000 rpm to 30,000 rpm, and more preferably 5,000 rpm to 20,000 rpm. The dispersion time is not particularly limited, but in the case of a batch method, it is usually 0.1 minutes to 5 minutes. The temperature during dispersion is preferably 0 ° C to 150 ° C (under pressure), more preferably 40 ° C to 98 ° C.

(C) At the same time as the preparation of the emulsion, the amines (B) are added to cause a reaction with the polyester prepolymer (A) having an isocyanate group. This reaction involves molecular chain crosslinking and / or elongation. The reaction time is selected depending on the reactivity of the isocyanate group structure of the polyester prepolymer (A) with the amines (B), but is usually 10 minutes to 40 hours, preferably 2 hours to 24 hours. The reaction temperature is generally 0 ° C to 150 ° C, preferably 40 ° C to 98 ° C. Moreover, a well-known catalyst can be used as needed. Specific examples include dibutyltin laurate and dioctyltin laurate.

(D) After the reaction is completed, the organic solvent is removed from the emulsified dispersion (reactant), washed and dried to obtain toner base particles.
In order to remove the organic solvent, the temperature of the entire system is gradually raised in a laminar stirring state, and after giving strong stirring in a certain temperature range, the solvent base is removed to produce spindle-shaped toner base particles. . In addition, when an acid such as calcium phosphate salt or an alkali-soluble material is used as a dispersion stabilizer, the calcium phosphate salt is dissolved from the toner base particles by a method such as washing with water after dissolving the calcium phosphate salt with an acid such as hydrochloric acid. Remove. It can also be removed by an operation such as degradation with an enzyme.

(E) Hydrophobic silica particles are externally added to the obtained toner base particles by mixing and stirring to obtain a toner.

As the developer to be accommodated in the developing device, the toner produced by the method described above is used.
In recent years, in order to achieve high image quality, a toner having a small particle size and a nearly spherical shape has been used. However, since toner cleaning becomes difficult in the present invention, hydrophobic silica particles are used as an external additive. By using it on the surface of the toner, it is possible to improve the cleaning property and to reduce the adhesion force between the photosensitive member and the toner or between the intermediate transfer belt and the toner. Further, the adhesion force between the toners can be reduced, and the fluidity and charging characteristics can be improved.
However, once the silica particles are detached from the toner, they easily adhere to the surface of the electrophotographic photoreceptor. Further, the adhering silica particles gradually accumulate or the toner resin adheres to the adhering silica particles. An abnormal image that increases and appears as an image tends to occur. In particular, since the cleaning blade has a function of removing toner by pressing strongly against the photoconductor, when the silica particles are separated from the toner by the cleaning blade, silica particles having a smaller particle diameter than the toner are contacted between the cleaning blade and the photoconductor. It is easy to enter and is strongly pressed, and as a result, it is easy to adhere to the photoreceptor.

  Therefore, in the present invention, by containing metal oxide particles having a specific particle diameter in the surface protective layer of the photoreceptor, it is possible to impart unevenness to the surface shape and to give the strength of the surface protective layer. It becomes possible. As a result, a fine nip is formed between the photoconductor and the cleaning blade, so that silica particles released from the toner can be prevented from adhering to the photoconductor due to pressing at the nip of the cleaning blade. Since silica particles that have passed through the cleaning blade can be removed with a cleaning brush provided on the downstream side, it is possible to always suppress the adhesion of silica particles on the photoreceptor and to obtain a good image without abnormal images. Become.

<Transfer process and transfer means>
The transfer step can be performed, for example, by charging the electrophotographic photosensitive member with the transfer charger using the visible image, and can be performed by the transfer unit. The transfer unit includes a primary transfer unit that transfers a visible image onto an intermediate recording medium to form a composite transfer image, and a secondary transfer unit that transfers the composite transfer image onto a recording medium. Embodiments are preferred.
Examples of the transfer device include a corona transfer device using corona discharge, a transfer belt, a transfer roller, a pressure transfer roller, and an adhesive transfer device.
The recording medium is typically plain paper, but is not particularly limited as long as it can transfer an unfixed image after development, and can be appropriately selected according to the purpose. PET for OHP A base or the like can also be used.

<Cleaning process and cleaning means>
The cleaning step is a step of removing toner and silica particles remaining on the electrophotographic photosensitive member, and can be suitably performed by a cleaning unit.
The cleaning means includes a cleaning blade and a cleaning brush, and the cleaning brush is provided downstream of the cleaning blade in the rotation direction of the electrophotographic photosensitive member. Further, in addition to the cleaning blade and the cleaning brush, a magnetic brush cleaner, an electrostatic brush cleaner, a magnetic roller cleaner, a blade cleaner, a web cleaner, and the like can be additionally provided.

The cleaning brush is made by implanting conductive fibers obtained by imparting conductivity to synthetic fibers made of a resin such as nylon, polyester, styrene, or acrylic on the base fabric so that the tip is looped or straight. Then, after the brush is formed, the base fabric is cut into a predetermined size and bonded while being wound around a rotatable core bar to produce a cleaning brush. The thickness of the conductive fiber is preferably 1 denier to 3 denier and the length is preferably 2 mm to 8 mm. Moreover, the flocking density of the conductive fibers is preferably 100,000 / inch ² to 400,000 / inch ² .
Of the synthetic fibers used in the cleaning brush, polyamide fibers are particularly effective because they can easily attract the hydrophobic silica particles by electrostatic attraction by frictional charging with the hydrophobic silica particles.

In the present invention, the cleaning means includes a cleaning blade and a cleaning brush, and the cleaning brush is disposed downstream of the cleaning blade in the rotation direction of the electrophotographic photosensitive member.
The cleaning process is performed using a cleaning blade and a cleaning brush, and the cleaning brush is disposed downstream of the cleaning blade in the rotation direction of the electrophotographic photosensitive member.

Here, FIG. 2 is a schematic configuration diagram showing an example of a state in which the cleaning unit acts on the electrophotographic photosensitive member in the present invention.
In FIG. 2, a photoreceptor 31 having a surface protective layer containing at least two kinds of metal oxide particles (hereinafter sometimes referred to as “photoreceptor 31”) rotates in the direction of arrow A, and the cleaning brush 32 is It rotates in the direction of arrow B.
The cleaning blade 35 is held and fixed to the holder 36, and its edge is pressed against the photoconductor 31 with a predetermined pressure in a so-called counter direction opposite to the rotation direction of the photoconductor 31.
The toner 30 remaining without being transferred from the surface of the photoreceptor to the recording medium such as transfer paper by the transfer unit is mechanically removed from the photoreceptor 31 by the cleaning blade 35. When the toner is removed by the cleaning blade, the hydrophobic silica particles 38 that are external additives of the toner are partly released from the toner 30 and slip through the cleaning blade 35. A cleaning brush 32 provided downstream of the cleaning blade 35 in the rotation direction of the photoconductor is provided so as to form a brush nip portion 37 with the photoconductor 31, and both the cleaning brush 32 and the photoconductor 31 rotate. The silica particles 38 are removed by mechanical rubbing. The rotation direction of the cleaning brush 32 may be in the same direction as the photoconductor or in the reverse direction at the brush nip portion 37. It is effective to rotate the cleaning brush 32 with a speed difference. Further, the cored bar 33 may be applied with a predetermined bias from a power source (not shown) or may be grounded.
The silica particles 38 that pass through the cleaning blade 35 and remain on the surface of the photosensitive member are electrically and mechanically transferred to the bristle portion of the cleaning brush 32 by the action of a bias applied to the core metal 33 at the brush nip portion 37, and become small particles. Silica particles 38, which are external additives with a diameter, are effectively removed. That is, in the present invention, when the cleaning blade 35 is pressed against the photoconductor 31, the silica particles 38 that are external additives of the toner are separated from the toner 30 and are attached to the photoconductor 31. Is used as a toner external additive due to the unevenness of the surface of the photoreceptor existing in the nip portion between the cleaning blade 35 and the photoreceptor 31. The silica particles 38 are prevented from being strongly pressed by the cleaning blade 35, and the silica particles 38 that have passed through the surface of the photoreceptor can be completely removed by the cleaning brush 32 existing on the downstream side of the cleaning blade 35. It is.
The cleaning brush 32 blows off the silica particles 38 adhering to the photoreceptor 31 by the flicker 34 that bites into the cleaning brush 32, and recovers the silica particles 38 in a silica recovery unit (not shown).
When the cleaning brush is used repeatedly, the cleaned toner accumulates in (between) the brush fibers, so that the flicker 34 is installed to strike the brush in order to remove the accumulated toner from the brush. Is.

-Fixing means-
The fixing means is a means for fixing the visible image transferred to the recording medium, and may be performed each time the toner of each color is transferred to the recording medium, or a state where the toner is stacked on the toner of each color. Can be done at the same time.
The fixing unit is not particularly limited and may be appropriately selected depending on the intended purpose, but a known heating and pressing unit is preferable. Examples of the heating and pressing means include a combination of a heating roller and a pressure roller, a combination of a heating roller, a pressure roller, and an endless belt. The heating in the heating and pressurizing means is preferably 80 ° C to 200 ° C.
In the present invention, for example, a known optical fixing device may be used together with or in place of the fixing unit depending on the purpose.

The neutralization step is a step of performing neutralization by applying a neutralization bias to the electrophotographic photosensitive member, and can be suitably performed by a neutralization unit.
The neutralization means is not particularly limited, and may be appropriately selected from known neutralizers as long as it can apply a neutralization bias to the electrophotographic photosensitive member. For example, a neutralization lamp is preferably used. Can be mentioned.

The recycling step is a step of recycling the electrophotographic color toner removed in the cleaning step to the developing unit, and can be suitably performed by the recycling unit.
There is no restriction | limiting in particular as said recycling means, A well-known conveyance means etc. are mentioned.

The control step is a step of controlling each of the steps, and can be suitably performed by a control unit.
The control means is not particularly limited as long as the movement of each means can be controlled, and can be appropriately selected according to the purpose. Examples thereof include devices such as a sequencer and a computer.

  The image forming apparatus of the present invention uses an electrophotographic photosensitive member having a surface protective layer. For example, after the electrophotographic photosensitive member is subjected to charging, exposure, and development processes, the toner image is transferred to a recording medium, fixed, and the photosensitive member. The image forming apparatus includes a process of surface cleaning. In some cases, an image forming method or the like in which an electrostatic latent image is directly transferred to a transfer member and developed does not necessarily have the above-described process arranged on a photosensitive member.

Here, FIG. 3 is a schematic view showing an example of the image forming apparatus of the present invention.
In this image forming apparatus, a charging roller 3 is used as a means for charging the photoconductor on average. Examples of other charging means include a corotron device, a scorotron device, a solid discharge element, a needle electrode device, a roller charging device, and a conductive brush device.

  Next, the image exposure unit 5 is used to form an electrostatic latent image on the uniformly charged photoreceptor 1. As this light source, for example, fluorescent materials such as fluorescent lamps, tungsten lamps, halogen lamps, mercury lamps, sodium lamps, light emitting diodes (LEDs), semiconductor lasers (LDs), electroluminescences (ELs) and the like can be used. In order to irradiate only light in a desired wavelength range, various filters such as a sharp cut filter, a band pass filter, a near infrared cut filter, a dichroic filter, an interference filter, and a color temperature conversion filter can be used. .

Next, the developing means 6 is used to visualize the electrostatic latent image formed on the photoreceptor 1. Development methods include a one-component development method using a dry toner and a two-component development method. When the photosensitive member is positively (negatively) charged and image exposure is performed, a positive (negative) electrostatic latent image is formed on the surface of the photosensitive member. A positive image can be obtained by developing this with negative (positive) toner (electrodetection fine particles), and a negative image can be obtained by developing with positive (negative) toner.
Next, a transfer charger 10 is used to transfer the toner image visualized on the photoreceptor onto the recording medium 9. In addition, a pre-transfer charger may be used for better transfer. As these transfer means, a transfer charger, an electrostatic transfer method using a bias roller, a mechanical transfer method such as an adhesive transfer method and a pressure transfer method, and a magnetic transfer method can be used. As the electrostatic transfer method, the charging means can be used.

Next, a separation charger and a separation claw are used as means for separating the recording medium 9 from the photoreceptor 1. As other separation means, electrostatic adsorption induction separation, side end belt separation, tip grip conveyance, curvature separation, and the like are used. As the separation charger, the charging means can be used.
Next, a fur brush 14 and a cleaning blade 15 are used to clean the toner remaining on the photoconductor after transfer. In addition, a pre-cleaning charger may be used for more efficient cleaning. Other cleaning means include a web method, a magnet brush method, and the like, but each may be used alone or in combination.

Next, a neutralizing unit is used for the purpose of removing the latent image on the photoreceptor as required. As the charge removal means, the charge removal lamp 2 and the charge removal charger are used, and the exposure light source and the charging means can be used respectively. In FIG. 3, reference numeral 8 denotes a registration roller.
In addition, known processes can be used for reading, feeding, fixing, paper discharge and the like that are not close to the photoconductor.
The present invention is an image forming apparatus using such an image forming unit. The image forming means may be fixedly incorporated in a copying apparatus, a facsimile machine, or a printer. However, as described below, the image forming means is incorporated in the image forming apparatus in the form of a process cartridge and is detachable. There may be.

(Process cartridge)
The process cartridge of the present invention includes an electrophotographic photosensitive member having a photosensitive layer and a surface protective layer containing at least two kinds of metal oxide particles on a support,
Developing means for developing a visible image by developing with a toner externally added with hydrophobized silica particles (hydrophobic silica particles);
Cleaning means for removing toner and hydrophobic silica particles remaining on the electrophotographic photosensitive member, and further having other means as required.
Further, as the charging unit, the exposure unit, the transfer unit, the cleaning unit, and the charge eliminating unit, the same ones as those of the above-described image forming apparatus can be appropriately selected and used.
The process cartridge can be detachably provided in various electrophotographic image forming apparatuses, facsimiles, and printers, and it is particularly preferable that the process cartridge is detachably provided in the image forming apparatus of the present invention.

The average thickness D (μm) of the surface protective layer in the electrophotographic photosensitive member, the particle size d1 (μm) of the metal oxide having the largest particle size among at least two types of metal oxide particles, and the smallest particle size The particle diameter d2 (μm) of the metal oxide satisfies the following expressions, d1 ≧ D / 5, and d1 ≧ 8 × d2.
The cleaning unit includes a cleaning blade and a cleaning brush, and the cleaning brush is disposed downstream of the cleaning blade in the rotation direction of the electrophotographic photosensitive member.

Here, FIG. 4 is a schematic view showing an example of the process cartridge of the present invention.
The process cartridge 105 in FIG. 4 includes an electrophotographic photosensitive member (photosensitive drum) 101, and includes a charging unit 102, a developing unit 104, a transfer unit 106, and a cleaning brush 107 and a cleaning blade 108 as a creening unit. Depending on the situation, other means are provided.

Next, the image forming process by the process cartridge 105 shown in FIG. 4 will be described. The electrophotographic photosensitive member 101 is exposed to the surface by charging by the charging means 102 and exposure means (not shown) while rotating in the direction of the arrow. An electrostatic latent image corresponding to the image is formed.
The electrostatic latent image is developed by the developing unit 104, and the obtained visible image is transferred to a recording medium (not shown) by the transfer unit 106 and printed out. Next, the surface of the electrophotographic photosensitive member after the image transfer is cleaned by the cleaning blade 108 and the cleaning brush 107, further neutralized by a neutralizing means (not shown), and the above operation is repeated again.

  An image forming apparatus, an image forming method, and a process cartridge according to the present invention are provided with a surface protective layer containing specific metal oxide particles and having high cleaning properties and wear resistance, and for toner removal. By having a cleaning means equipped with a cleaning blade and a cleaning brush for removing hydrophobic silica particles, it becomes possible to prevent silica particles from adhering to the electrophotographic photoreceptor, so that high definition and high image quality can be achieved over a long period of time. An image can be formed.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

(Toner Production Example 1)
<Preparation of toner base particles>
-Synthesis of unmodified polyester resin-
229 parts by mass of bisphenol A ethylene oxide 2-mole adduct, 529 parts by mass of bisphenol A propion oxide 3-mole adduct, 208 parts by mass of terephthalic acid, adipic acid 46 Part by mass and 2 parts by mass of dibutyltin oxide were added and reacted at 230 ° C. for 8 hours under normal pressure. Next, after reacting under reduced pressure of 10 mmHg to 15 mmHg for 5 hours, 44 parts by mass of trimellitic anhydride was added to the reaction vessel and reacted at 180 ° C. for 2 hours under normal pressure to synthesize an unmodified polyester resin. did.
The obtained unmodified polyester resin had a number average molecular weight of 2,500, a weight average molecular weight of 26,000, a glass transition temperature of 43 ° C., and an acid value of 25 mgKOH / g.

-Preparation of master batch-
1,200 parts by weight of water, 540 parts by weight of carbon black Printex 35 (manufactured by Dexa, DBP oil absorption = 42 ml / 100 mg, pH = 9.5), and 1,200 parts by weight of the synthesized unmodified polyester resin were added to a Henschel mixer. (Mitsui Mining Co., Ltd.) was used for mixing. The obtained mixture was kneaded at 150 ° C. for 30 minutes using two rolls, then rolled and cooled, and pulverized with a pulverizer (manufactured by Hosokawa Micron Corporation) to prepare a master batch.

In a reaction vessel equipped with a stirring bar and a thermometer, 378 parts by mass of the synthesized unmodified polyester resin, 110 parts by mass of carnauba wax, 22 parts by mass of a salicylic acid metal complex (E-84, manufactured by Orient Chemical Industries), and 947 parts by mass of ethyl acetate was added, the temperature was raised to 80 ° C. with stirring, the temperature was maintained at 80 ° C. for 5 hours, and then cooled to 30 ° C. over 1 hour. Next, 500 parts by mass of the master batch and 500 parts by mass of ethyl acetate were charged into the reaction vessel and mixed for 1 hour to obtain a raw material solution.
1,324 parts by mass of the obtained raw material solution was transferred to a reaction vessel, and filled with 80% by volume of 0.5 mm zirconia beads using a bead mill, Ultraviscomil (manufactured by Imex), and the feed rate was 1 kg / hour. The carnauba wax was dispersed by three passes under the condition that the disk peripheral speed was 6 m / sec to obtain a wax dispersion.

  Next, 1,324 parts by mass of a 65% by mass ethyl acetate solution of the synthesized unmodified polyester resin was added to the wax dispersion. A layered inorganic mineral montmorillonite (Clayton APA Southern) modified with a quaternary ammonium salt having at least a part of benzyl group was added to 200 parts by mass of a dispersion obtained by one pass using Ultraviscomil under the same conditions as above. 3 parts by mass) (manufactured by Cray Products) was added. K. The mixture was stirred for 30 minutes using a homodisper (manufactured by Tokushu Kika Kogyo Co., Ltd.) to obtain a toner material dispersion.

In a reaction vessel equipped with a cooling tube, a stirrer, and a nitrogen introduction tube, 682 parts by mass of bisphenol A ethylene oxide 2 mol adduct, 81 parts by mass of bisphenol A propylene oxide 2 mol adduct, 283 parts by mass of terephthalic acid, and anhydrous Trimellitic acid 22 parts by mass and dibutyltin oxide 2 parts by mass were charged and reacted at 230 ° C. for 8 hours under normal pressure. Next, it was made to react under reduced pressure of 10 mmHg-15 mmHg for 5 hours, and the intermediate polyester resin was synthesize | combined.
The obtained intermediate polyester resin had a number average molecular weight of 2,100, a weight average molecular weight of 9,500, a glass transition temperature of 55 ° C., an acid value of 0.5 mgKOH / g, and a hydroxyl value of 51 mgKOH / g. .

  Next, 410 parts by mass of the intermediate polyester resin, 89 parts by mass of isophorone diisocyanate, and 500 parts by mass of ethyl acetate are charged in a reaction vessel equipped with a cooling tube, a stirrer, and a nitrogen introduction tube, and reacted at 100 ° C. for 5 hours. To prepare a prepolymer. The free isocyanate content of the obtained prepolymer was 1.53% by mass.

In a reaction vessel equipped with a stirrer and a thermometer, 170 parts by mass of isophoronediamine and 75 parts by mass of methyl ethyl ketone were charged and reacted at 50 ° C. for 5 hours to synthesize a ketimine compound. The amine value of the obtained ketimine compound was 418 mgKOH / g.
In a reaction vessel, 749 parts by mass of a dispersion of toner material, 115 parts by mass of a prepolymer, and 2.9 parts by mass of a ketimine compound are charged, and 1 at 5,000 rpm using a TK homomixer (manufactured by Tokushu Kika) Mixing for a minute gave an oil phase mixture.

-Preparation of resin particle dispersion-
In a reaction vessel in which a stir bar and a thermometer are set, 683 parts by mass of water, 11 parts by mass of reactive emulsifier (sodium salt of methacrylic acid ethylene oxide adduct, Eleminol RS-30, Sanyo Chemical Industries) Then, 83 parts by mass of styrene, 83 parts by mass of methacrylic acid, 110 parts by mass of butyl acrylate, and 1 part by mass of ammonium persulfate were charged and stirred at 400 rpm for 15 minutes to obtain an emulsion. The emulsion was heated, heated to 75 ° C. and reacted for 5 hours. Next, 30 parts by mass of a 1% by mass aqueous ammonium persulfate solution was added and aged at 75 ° C. for 5 hours to prepare a resin particle dispersion.

  Next, 990 parts by weight of water, 83 parts by weight of the resin particle dispersion, 37 parts by weight of 48.5% by weight aqueous solution of eleminol MON-7 (manufactured by Sanyo Chemical Industries) of sodium dodecyl diphenyl ether disulfonate, as a polymer dispersant An aqueous medium was obtained by mixing and stirring 135 parts by mass of a 1% by mass aqueous solution of sodium carboxymethylcellulose (Serogen BS-H-3, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) and 90 parts by mass of ethyl acetate.

867 parts by mass of the oil phase mixed liquid was added to 1,200 parts by mass of the obtained aqueous medium, and mixed at 13,000 rpm for 20 minutes using a TK homomixer to prepare a dispersion (emulsion slurry). .
Furthermore, the emulsified slurry was charged into a reaction vessel equipped with a stirrer and a thermometer, and after removing the solvent at 30 ° C. for 8 hours, aging was performed at 45 ° C. for 4 hours to obtain a dispersed slurry.
Subsequently, 100 parts by mass of the dispersed slurry was filtered under reduced pressure, 100 parts by mass of ion-exchanged water was added to the filter cake, and the mixture was mixed for 10 minutes at 12,000 rpm using a TK homomixer, and then filtered.

To the obtained filter cake, 10% by mass hydrochloric acid was added to adjust the pH to 2.8, followed by mixing at 12,000 rpm for 10 minutes using a TK homomixer, followed by filtration.
Further, 300 parts by mass of ion-exchanged water was added to the obtained filter cake, mixed at 12,000 rpm for 10 minutes using a TK homomixer, and then filtered twice to obtain a final filter cake.
The obtained final filter cake was dried at 45 ° C. for 48 hours using a circulating drier and sieved with a mesh having a mesh size of 75 μm to obtain toner base particles.

-External additives-
To 100 parts by mass of the obtained toner base particles, 1.5 parts by mass of hydrophobic silica particles having a surface treatment with hexamethyldisilazane of 65% and an average primary particle diameter of 140 nm were added. (Mine Co., Ltd.) for 3 minutes under conditions of a peripheral speed of 33 m / s. The mixed powder was passed through a mesh having a mesh size of 38 μm, and coarse powder was removed to prepare toner 1 to which hydrophobic silica particles were externally added.

(Toner Production Example 2)
In Toner Production Example 1, Toner 2 was produced in the same manner as in Toner Production Example 1, except that an external additive was externally added as follows.
-External additives-
To 100 parts by mass of the obtained toner base particles, 1.5 parts by mass of silica particles having an average primary particle diameter of 140 nm that are not surface-treated are added, and the peripheral speed is 33 m / s by using a Henschel mixer (manufactured by Mitsui Mining Co., Ltd.). For 3 minutes. The mixed powder was passed through a mesh having a mesh size of 38 μm, coarse powder was removed, and toner 2 to which silica particles were externally added was produced.

(Photoreceptor Preparation Example 1)
<Production of electrophotographic photoreceptor>
An undercoating layer coating solution, a charge generation layer coating solution, and a charge transport layer coating solution having the following composition are sequentially applied by dip coating on an aluminum cylinder having an outer diameter of 100 mm, dried, and dried to a thickness of 3 An undercoat layer of 0.5 μm, a charge generation layer having a thickness of 0.2 μm, and a charge transport layer having a thickness of 23 μm were formed.

-Undercoat layer coating solution-
・ Alkyd resin (Beckosol 1307-60-EL, manufactured by Dainippon Ink & Chemicals, Inc.) ... 6 parts by mass Melamine resin (Super Becamine G-821-60, manufactured by Dainippon Ink & Chemicals, Inc.)・ 4 parts by mass ・ Titanium oxide: 40 parts by mass ・ Methyl ethyl ketone: 50 parts by mass

-Charge generation layer coating solution-
-Bisazo pigment represented by the following structural formula: 2.5 parts by mass
・ Polyvinyl butyral (XYHL, manufactured by UCC): 0.5 part by mass ・ Cyclohexanone: 200 part by mass ・ Methyl ethyl ketone: 80 part by mass

-Charge transport layer coating solution-
-Bisphenol Z-type polycarbonate (Panlite TS-2050, manufactured by Teijin Chemicals Ltd.) ... 10 parts by mass-Charge transport material represented by the following structural formula: 7 parts by mass
Tetrahydrofuran: 100 parts by mass Tetrahydrofuran solution of 1 mass% silicone oil (KF50-100CS, manufactured by Shin-Etsu Chemical Co., Ltd.): 1 part by mass

Next, spray coating is performed on the charge transport layer using a surface protective layer coating solution having the following composition, and light irradiation is performed under the conditions of a metal halide lamp, irradiation intensity: 500 mW / cm ² , and irradiation time: 20 seconds. And further dried at 130 ° C. for 30 minutes to form a surface protective layer having an average thickness of 1.4 μm. Thus, the electrophotographic photoreceptor 1 was produced.
-Surface protective layer coating solution-
Trifunctional radical polymerizable compound (trimethylolpropane triacrylate, TMPTA, manufactured by Tokyo Chemical Industry Co., Ltd.) ... 80 parts by mass Aluminum oxide particles having an average primary particle size of 0.3 μm (Advanced Alumina AA-03, Sumitomo Chemical) 20 parts by mass of conductive tin oxide particles having an average primary particle size of 30 nm (S-2000, manufactured by Mitsubishi Materials Corporation) 10 parts by mass of photopolymerization initiator (1-hydroxy-cyclohexyl) -Phenyl-ketone, Irgacure 184, manufactured by Ciba Specialty Chemicals) ... 4 parts by mass Tetrahydrofuran ... 1,200 parts by mass

(Photoreceptor preparation example 2)
<Production of electrophotographic photoreceptor>
An electrophotographic photoreceptor 2 was produced in the same manner as in the photoreceptor preparation example 1 except that the surface protective layer coating solution in the photoreceptor preparation example 1 was changed to the following.
-Surface protective layer coating solution-
Trifunctional radical polymerizable compound (trimethylolpropane triacrylate, TMPTA, manufactured by Tokyo Chemical Industry Co., Ltd.) ... 80 parts by mass Aluminum oxide particles having an average primary particle size of 0.5 μm (Advanced Alumina AA-05, Sumitomo Chemical) 20 parts by mass of conductive tin oxide particles having an average primary particle size of 30 nm (S-2000, manufactured by Mitsubishi Materials Corporation) 10 parts by mass of photopolymerization initiator (1-hydroxy-cyclohexyl) -Phenyl-ketone, Irgacure 184, manufactured by Ciba Specialty Chemicals) ... 4 parts by mass Tetrahydrofuran ... 1,200 parts by mass

(Photoreceptor Preparation Example 3)
<Production of electrophotographic photoreceptor>
An electrophotographic photoreceptor 3 was produced in the same manner as in the photoreceptor preparation example 1 except that the surface protective layer coating solution in the photoreceptor preparation example 1 was changed to the following.
-Surface protective layer coating solution-
Trifunctional radical polymerizable compound (trimethylolpropane triacrylate, TMPTA, manufactured by Tokyo Chemical Industry Co., Ltd.) ... 80 parts by mass Aluminum oxide particles having an average primary particle size of 0.5 μm (Advanced Alumina AA-05, Sumitomo Chemical) 15 parts by mass ・ Aluminum oxide particles with an average primary particle size of 0.1 μm (Tymicron TM-DAR, manufactured by Daimei Chemical Co., Ltd.) 7.5 parts by mass ・ Conductivity with an average particle size of 30 nm -Based tin oxide particles (S-2000, manufactured by Mitsubishi Materials Corporation) 7.5 parts by mass Photopolymerization initiator (1-hydroxy-cyclohexyl-phenyl-ketone, Irgacure 184, manufactured by Ciba Specialty Chemicals) ... 4 parts by mass Tetrahydrofuran ... 1,200 parts by mass

(Photosensitive member production example 4)
<Production of electrophotographic photoreceptor>
An electrophotographic photoreceptor 4 was produced in the same manner as in the photoreceptor preparation example 2 except that the average thickness of the surface protective layer in the photoreceptor preparation example 2 was changed from 1.4 μm to 0.8 μm.

(Photoreceptor Preparation Example 5)
<Production of electrophotographic photoreceptor>
An electrophotographic photoreceptor 5 was produced in the same manner as in the photoreceptor preparation example 2 except that the average thickness of the surface protective layer in the photoreceptor preparation example 2 was changed from 1.4 μm to 2.0 μm.

(Photosensitive member preparation example 6)
<Production of electrophotographic photoreceptor>
An electrophotographic photoreceptor 6 was produced in the same manner as in the photoreceptor preparation example 2 except that the thickness of the surface protective layer in the photoreceptor preparation example 2 was changed from 1.4 μm to 0.6 μm.

(Photoreceptor Preparation Example 7)
<Production of electrophotographic photoreceptor>
An electrophotographic photoreceptor 7 was produced in the same manner as in the photoreceptor preparation example 1 except that the surface protective layer coating solution in the photoreceptor preparation example 1 was changed to the following.
-Surface protective layer coating solution-
Trifunctional radical polymerizable compound (trimethylolpropane triacrylate, TMPTA, manufactured by Tokyo Chemical Industry Co., Ltd.) ... 80 parts by mass Aluminum oxide particles having an average primary particle size of 0.3 μm (Advanced Alumina AA-03, Sumitomo Chemical) 20 mass parts ・ Aluminum oxide particles with an average primary particle size of 31 nm (NanoTek Powder, manufactured by CI Kasei Co., Ltd.) 10 mass parts ・ Photopolymerization initiator (1-hydroxy-cyclohexyl-phenyl-ketone) , Irgacure 184, manufactured by Ciba Specialty Chemicals) ... 4 parts by mass Tetrahydrofuran ... 1,200 parts by mass

(Photoreceptor Preparation Example 8)
<Production of electrophotographic photoreceptor>
An electrophotographic photoreceptor 8 was produced in the same manner as in the photoreceptor preparation example 1 except that the surface protective layer coating solution in the photoreceptor preparation example 1 was changed to the following.
-Surface protective layer coating solution-
Trifunctional radical polymerizable compound (trimethylolpropane triacrylate, TMPTA, manufactured by Tokyo Chemical Industry Co., Ltd.) ... 80 parts by mass Aluminum oxide particles having an average primary particle size of 0.3 μm (Advanced Alumina AA-03, Sumitomo Chemical) 10 parts by mass. Conductive tin oxide particles having an average primary particle size of 30 nm (S-2000, manufactured by Mitsubishi Materials Corporation) ... 20 parts by mass. Photopolymerization initiator (1-hydroxy-cyclohexyl-) Phenyl-ketone, Irgacure 184, manufactured by Ciba Specialty Chemicals) ... 4 parts by mass Tetrahydrofuran ... 1,200 parts by mass

(Photoreceptor Preparation Example 9)
<Production of electrophotographic photoreceptor>
An electrophotographic photoreceptor 9 was produced in the same manner as in the photoreceptor preparation example 1 except that the surface protective layer coating solution in the photoreceptor preparation example 1 was changed to the following.
-Surface protective layer coating solution-
Bifunctional radically polymerizable compound (KAYARAD NPGDA, Nippon Kayaku Co., Ltd.) ... 80 parts by mass Aluminum oxide particles having an average primary particle size of 0.3 μm (Advanced Alumina AA-03, Sumitomo Chemical Co., Ltd.) ... 20 parts by mass-Conductive tin oxide particles having an average primary particle size of 30 nm (S-2000, manufactured by Mitsubishi Materials Corporation) ... 10 parts by mass-Photopolymerization initiator (1-hydroxy-cyclohexyl-phenyl-ketone) , Irgacure 184, manufactured by Ciba Specialty Chemicals) ... 4 parts by mass Tetrahydrofuran ... 1,200 parts by mass

(Photoreceptor Preparation Example 10)
<Production of electrophotographic photoreceptor>
The surface protective layer coating solution of Photoreceptor Preparation Example 1 was changed to the following, and the same procedure as in Photoreceptor Preparation Example 1 was performed except that the average thickness of the surface protective layer was changed from 1.4 μm to 0.6 μm. Thus, an electrophotographic photoreceptor 10 was produced.
-Surface protective layer coating solution-
Trifunctional radically polymerizable compound (trimethylolpropane triacrylate, TMPTA, manufactured by Tokyo Chemical Industry Co., Ltd.) ... 80 parts by mass Photopolymerization initiator (1-hydroxy-cyclohexyl-phenyl-ketone, Irgacure 184, Ciba Specialty Chemicals Co., Ltd.) ... 4 parts by mass Tetrahydrofuran ... 1,200 parts by mass

(Photoreceptor Preparation Example 11)
<Production of electrophotographic photoreceptor>
An electrophotographic photoreceptor 11 was produced in the same manner as in the photoreceptor preparation example 1 except that the surface protective layer coating solution in the photoreceptor preparation example 1 was changed to the following.
-Surface protective layer coating solution-
Trifunctional radically polymerizable compound (trimethylolpropane triacrylate, TMPTA, manufactured by Tokyo Chemical Industry Co., Ltd.) ... 80 parts by mass Conductive tin oxide particles having an average primary particle size of 30 nm (S-2000, Mitsubishi Materials Corporation) 30 parts by mass. Photopolymerization initiator (1-hydroxy-cyclohexyl-phenyl-ketone, Irgacure 184, manufactured by Ciba Specialty Chemicals) ... 4 parts by mass Tetrahydrofuran ... 1,200 parts by mass Part

(Photoconductor Preparation Example 12)
<Production of electrophotographic photoreceptor>
An electrophotographic photoreceptor 12 was produced in the same manner as in the photoreceptor preparation example 1 except that the average thickness of the surface protective layer in the photoreceptor preparation example 1 was changed from 1.4 μm to 2.5 μm.

(Photoreceptor Preparation Example 13)
<Production of electrophotographic photoreceptor>
An electrophotographic photoreceptor 13 was produced in the same manner as in the photoreceptor preparation example 1 except that the surface protective layer coating solution in the photoreceptor preparation example 1 was changed to the following.
-Surface protective layer coating solution-
Trifunctional radical polymerizable compound (trimethylolpropane triacrylate, TMPTA, manufactured by Tokyo Chemical Industry Co., Ltd.) ... 80 parts by mass Aluminum oxide particles having an average primary particle size of 0.3 μm (Advanced Alumina AA-03, Sumitomo Chemical) 20 parts by mass ・ Aluminum oxide particles having an average primary particle size of 0.1 μm (Tymicron TM-DAR, manufactured by Daimei Chemical Co., Ltd.) 10 parts by mass Hydroxy-cyclohexyl-phenyl-ketone, Irgacure 184, manufactured by Ciba Specialty Chemicals) ... 4 parts by mass Tetrahydrofuran ... 1,200 parts by mass

(Photoreceptor Preparation Example 14)
<Production of electrophotographic photoreceptor>
An electrophotographic photoreceptor 14 was produced in the same manner as in the photoreceptor preparation example 1 except that the surface protective layer coating solution in the photoreceptor preparation example 1 was changed to the following.
-Surface protective layer coating solution-
Trifunctional radical polymerizable compound (trimethylolpropane triacrylate, TMPTA, manufactured by Tokyo Chemical Industry Co., Ltd.) ... 80 parts by mass Aluminum oxide particles having an average primary particle size of 0.1 μm (Tymicron TM-DAR, Daimei Chemical Industrial Co., Ltd.) 20 parts by mass. Conductive tin oxide particles having an average primary particle size of 30 nm (S-2000, manufactured by Mitsubishi Materials Corporation) 10 parts by mass. Photopolymerization initiator (1-hydroxy- (Cyclohexyl-phenyl-ketone, Irgacure 184, manufactured by Ciba Specialty Chemicals) ... 4 parts by mass Tetrahydrofuran ... 1,200 parts by mass

(Cleaning brush production example 1)
Nylon conductive fiber carbon belt 931 (KB Seiren Co., Ltd.) is planted on the base fabric so that the tip is looped, a brush is formed, the base fabric is cut into a string of 10 mm width, A loop-shaped cleaning brush 1 wound around a 9 mm brass rod rod and attached and fixed using an adhesive was produced.

(Cleaning brush production example 2)
Acrylic conductive fiber SA-7 (manufactured by Toray Industries, Inc.) is planted on a base fabric so that the tip is looped, a brush is formed, the base fabric is cut into a string having a width of 10 mm, and a diameter of 9 mm. A loop-shaped cleaning brush 2 wound around a brass rod rod and fixed using an adhesive was prepared.

(Cleaning brush preparation example 3)
Polyester conductive fiber carbon beltlon B31 (KB Seiren Co., Ltd.) is planted on the base fabric so that the tip is looped, a brush is formed, the base fabric is cut into a string of 10 mm width, A loop-shaped cleaning brush 3 wound around a 9 mm brass rod rod and attached and fixed using an adhesive was produced.

  Next, the ten-point average roughness Rz was measured for each produced electrophotographic photosensitive member as follows. The results are shown in Table 1. Further, the average thickness D of the surface protective layer of the electrophotographic photosensitive member was measured as follows. The results are shown in Table 1.

<Measurement of ten-point average roughness Rz>
Using a surface roughness measuring machine (Surfcom 1400D, manufactured by Tokyo Seimitsu Co., Ltd.), the 10-point average roughness Rz was measured based on the standard JIS B 0601: 2001 for surface roughness. The measurement results are shown in Table 1.

<Measurement of average thickness D of surface protective layer>
Using an eddy current film thickness meter (Fisherscope MMS, manufactured by Fischer Instruments Co., Ltd.), the thickness before and after coating the surface protective layer was measured to determine the thickness of the surface protective layer. At that time, an average value of thicknesses obtained by measuring six locations at intervals of 50 mm along the photosensitive member longitudinal direction was derived as an average thickness D.

<Image evaluation>
Next, using the produced toner, electrophotographic photosensitive member, cleaning blade, and cleaning brush, each member of the standard equipment of the image forming apparatus (digital copier, imagio MP9001, manufactured by Ricoh Co., Ltd.) in the combinations shown in Table 2 Replaced and modified. The cleaning conditions in Table 2 are listed in the order of arrangement upstream to downstream in the rotation direction of the electrophotographic photosensitive member.
Using each modified image forming apparatus, continuous test of 100,000 sheets of 5% image area ratio A4 size vertical chart (manufactured by Ricoh Co., Ltd.) in a normal temperature and humidity environment (55% RH at 23 ° C.). Then, image evaluation after repeated use was performed. The results are shown in Table 3.

* In Comparative Example 9, a cleaning brush is disposed on the upstream side in the rotation direction of the electrophotographic photosensitive member, and a cleaning blade is disposed on the downstream side.

From the results of Table 3, as shown in Examples 1 to 11, at least one kind of electrophotographic photosensitive member provided with a surface protective layer containing at least two kinds of specific metal oxide particles on the surface of toner base particles. In Comparative Examples 1 to 9, image forming apparatuses using toners externally added with hydrophobized silica particles (hydrophobic silica particles) and having at least a cleaning blade and a cleaning brush on the downstream side as cleaning means are described in Comparative Examples 1 to 9. In comparison, it is clear that a good image without an abnormal image can be obtained over a long period of time.

  The image forming apparatus, the image forming method, and the process cartridge of the present invention include, for example, a laser printer, a direct digital plate making machine, a full color copier using a direct or indirect electrophotographic multicolor image developing system, a full color laser printer, and a full color. Can be widely used for plain paper fax machines.

DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Static elimination lamp 3 Charging roller 5 Image exposure part 6 Developing means 8 Registration roller 9 Recording medium 10 Transfer charge 14 Cleaning brush 15 Cleaning blade 21 Support body 22 Photosensitive layer 24 Undercoat layer 25 Charge generation layer 26 Charge transport layer 28 Surface protective layer 30 Toner 31 Photoconductor 32 Cleaning brush 33 Core metal 34 Flicker 35 Blade 36 Blade holder 37 Brush nip portion 38 Silica particles 101 Photosensitive drum 102 Charging means 104 Developing means 105 Process cartridge 106 Transfer means 107 Cleaning brush 108 Cleaning blade A Photosensitive Body rotation direction B Cleaning brush rotation direction

JP-A-48-47345 Japanese Patent Laid-Open No. 8-248851 JP 2001-242758 A JP 2002-055582 A JP-A-2005-208622 Japanese Patent Laid-Open No. 9-22155 JP-A-11-167224 Japanese Patent No. 2793647 Japanese Patent No. 2619424 JP-A-8-314175 JP 2006-259588 A JP 2007-193255 A JP 2007-147767 A JP 2007-171627 A

Claims (9)

An electrophotographic photosensitive member having a photosensitive layer and a surface protective layer containing at least two kinds of metal oxide particles on a support;
Charging means for charging the surface of the electrophotographic photosensitive member;
Exposure means for exposing the charged electrophotographic photosensitive member surface to form an electrostatic latent image; and
Developing means for developing the electrostatic latent image using a toner to which silica particles subjected to hydrophobic treatment are externally added to form a visible image;
Transfer means for transferring the visible image to a recording medium;
Cleaning means for removing toner and silica particles remaining on the electrophotographic photosensitive member,
The average thickness D (μm) of the surface protective layer in the electrophotographic photosensitive member, the particle diameter d1 (μm) of the metal oxide particle having the largest particle diameter among at least two kinds of metal oxide particles, and the largest particle diameter The particle size d2 (μm) of the small metal oxide particles satisfies the following formulas, d1 ≧ D / 5, and d1 ≧ 8 × d2,
The image forming apparatus, wherein the cleaning unit includes a cleaning blade and a cleaning brush, and the cleaning brush is disposed downstream of the cleaning blade in the rotation direction of the electrophotographic photosensitive member.   The image forming apparatus according to claim 1, wherein the ten-point average roughness Rz (μm) of the surface of the electrophotographic photosensitive member and the average thickness D (μm) of the surface protective layer satisfy the following formula: Rz ≧ D / 2.   The image forming apparatus according to claim 1, wherein the average thickness D of the surface protective layer is 0.8 μm to 1.5 μm.   4. The image forming apparatus according to claim 1, wherein the metal oxide having the smallest particle size among the at least two kinds of metal oxide particles in the surface protective layer is a conductive metal oxide particle. 5.   The content mass of the metal oxide particles having the largest particle size among the at least two types of metal oxide particles in the surface protective layer is larger than the mass content of the metal oxide particles having the smallest particle size. The image forming apparatus described in 1.   The image forming apparatus according to claim 1, wherein the surface protective layer includes a cured product obtained by polymerizing a radically polymerizable compound having three or more functions.   The image forming apparatus according to claim 1, wherein the cleaning brush includes a polyamide fiber. A charging step of charging the surface of an electrophotographic photosensitive member having a photosensitive layer and a surface protective layer containing at least two kinds of metal oxide particles on a support;
Exposing the charged electrophotographic photoreceptor surface to form an electrostatic latent image; and
A developing step of developing the electrostatic latent image using a toner to which silica particles subjected to a hydrophobic treatment are externally added to form a visible image;
A transfer step of transferring the visible image to a recording medium;
A cleaning step of removing toner and silica particles remaining on the electrophotographic photosensitive member,
The average thickness D (μm) of the surface protective layer in the electrophotographic photosensitive member, the particle diameter d1 (μm) of the metal oxide particle having the largest particle diameter among at least two kinds of metal oxide particles, and the largest particle diameter The particle size d2 (μm) of the small metal oxide particles satisfies the following formulas, d1 ≧ D / 5, and d1 ≧ 8 × d2,
The image forming method, wherein the cleaning step is performed using a cleaning blade and a cleaning brush, and the cleaning brush is disposed downstream of the cleaning blade in the rotation direction of the electrophotographic photosensitive member. An electrophotographic photosensitive member having a photosensitive layer and a surface protective layer containing at least two kinds of metal oxide particles on a support;
Developing means for developing a visible image by developing with toner having externally added silica particles hydrophobized;
A process cartridge having at least cleaning means for removing toner and silica particles remaining on the electrophotographic photosensitive member,
The average thickness D (μm) of the surface protective layer in the electrophotographic photosensitive member, the particle diameter d1 (μm) of the metal oxide particle having the largest particle diameter among at least two kinds of metal oxide particles, and the largest particle diameter The particle size d2 (μm) of the small metal oxide particles satisfies the following formulas, d1 ≧ D / 5, and d1 ≧ 8 × d2,
The process cartridge, wherein the cleaning means includes a cleaning blade and a cleaning brush, and the cleaning brush is disposed downstream of the cleaning blade in the rotation direction of the electrophotographic photosensitive member.