JP2007086734A - Electrophotographic image forming apparatus, electrophotographic photoreceptor, and image forming unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic image forming apparatus, a photoreceptor and an image forming unit by which a high quality toner image can be continuously obtained while preventing a white void in a solid image or a hollow part in a character image, occurrence black spots or fogging in the course of printing a large number of prints, and avoiding decrease in the image density or decrease in sharpness. <P>SOLUTION: The electrophotographic image forming apparatus includes a first transferring means to transfer a toner image formed on an electrophotographic photoreceptor by at least a charging means, an exposing means and a developing means, onto an intermediate transfer body member, and a second transferring means to transfer the toner image on the intermediate transfer member to a recording medium; wherein the electrophotographic photoreceptor has a surface layer containing particles having a number average primary particle diameter of 1 to 300 nm and the surface layer has a hardness (universal hardness) of 200 to 350 N/mm<SP>2</SP>which is lower than the hardness (universal hardness) of the surface layer of the intermediate transfer member. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electrophotographic image forming apparatus, an electrophotographic photosensitive member, and an image forming unit.

  In recent years, digital image forming methods have become mainstream due to the progress of digital technology. A digital image forming method is required to visualize a small dot image of one pixel such as 1200 dpi (dpi in the present invention represents the number of dots per inch, that is, 2.54 cm). In some cases, there is a demand for high image quality technology that faithfully reproduces such a small dot image. In particular, in recent years, there has been an increasing demand for miniaturization, high resolution, and full color copying machines, and in the case of printers, stable creation of high-quality images comparable to printing. In order to stably obtain a high-quality toner image, a higher image quality enhancement technique is required.

  In order to obtain high-quality images, development means and electrophotographic photoreceptors have been studied.

  The developing means in the electrophotographic technology is roughly divided into two types: a dry developing means and a wet developing means.

  The dry developing means is a method using a toner made of powder, and further, a dry two-component type in which the developer is composed of toner, carrier and other additives, and a dry one-component type in which the carrier is not included and is composed of toner and other additives. It is divided into two.

  On the other hand, the wet developing means is a developing method using a liquid developer in which toner is dispersed in a carrier liquid. Compared with dry development means, wet development means have advantages such as finer toner particle size and high toner transparency, and high quality toner images can be obtained regardless of analog, digital, monochrome, or color. And an energy-saving image forming apparatus can be obtained.

The toner image formed on the electrophotographic photosensitive member is applied with a transfer bias voltage to a transfer roller provided in contact with the image carrier by a bias voltage applying unit. In the image forming apparatus transferred to the surface, an insulating layer having a volume resistivity of 1 × 10 ⁷ Ωcm or more is formed on the surface of the transfer roller, and the insulating layer has a hardness of the surface layer of the image carrier. The image forming apparatus is characterized in that the bias voltage applying means has a function of applying to the transfer roller a removal bias voltage for transferring the toner adhering to the transfer roller onto the image carrier. (For example, refer to Patent Document 1).

  In addition, in order to prevent local transfer omission, the hardness of the electrophotographic photosensitive member and the intermediate transfer member has been studied. In this study, it has been proposed that the dynamic hardness of the surface of the electrophotographic photosensitive member be made larger than the intermediate transfer member hardness (see, for example, Patent Document 2).

In addition, as an electrophotographic photosensitive member for obtaining a large number of high-quality toner images, a proposal has been made to include particles in the surface layer (see, for example, Patent Document 3).
JP 2004-94037 A JP 2003-149950 A JP 2005-43623 A

  However, when the proposed electrophotographic photosensitive member (hereinafter also simply referred to as a photosensitive member) is used in the electrophotographic image forming apparatus (hereinafter also simply referred to as an image forming apparatus) of the present invention, solid images of white or character images may be removed. Blackouts and fogging occur when a number of prints are printed, or the image density is lowered or the sharpness is lowered, and a high-quality toner image cannot be continuously obtained. Further improvements were desired.

  An object of the present invention is to provide an image forming apparatus, a photoreceptor, and an image forming unit that can continuously obtain a high-quality toner image free from image defects.

  The object of the present invention is achieved by adopting the following configuration.

1.
At least a charging unit, an exposure unit, a developing unit that develops with a developer containing toner, a primary transfer unit that transfers a toner image formed by the developing unit onto the intermediate transfer member, and a toner on the intermediate transfer member. In an electrophotographic image forming apparatus having secondary transfer means for transferring an image to a recording medium,
The electrophotographic photoreceptor contains particles having a number average primary particle size of 1 to 300 nm on the surface layer thereof,
Hardness of the surface layer (universal hardness) of at 200~350N / mm ^2,
An electrophotographic image forming apparatus characterized by being softer than the hardness (universal hardness) of the surface layer of the intermediate transfer member.

2.
2. The electrophotographic image forming apparatus according to 1 above, wherein the particles include at least inorganic particles and organic particles.

3.
3. The electrophotographic image forming apparatus according to 1 or 2, wherein the inorganic particles are selected from silica particles, alumina particles, titanium dioxide particles, and strontium titanate particles.

4).
3. The electrophotographic image forming apparatus according to 1 or 2, wherein the organic particles are selected from fluorine atom-containing resin particles, silicon atom-containing resin particles, polyolefin particles, and polyester particles.

5.
2. The electrophotographic image forming apparatus as described in 1 above, wherein the surface layer of the electrophotographic photosensitive member is a charge transport layer.

6).
2. The electrophotographic image forming apparatus according to 1 above, wherein the surface layer of the electrophotographic photosensitive member is a protective layer.

7).
2. The electrophotographic image forming apparatus according to 1 above, wherein the toner contains at least lubricant particles and abrasive particles.

8).
2. The electrophotographic image forming apparatus as described in 1 above, wherein an elastic blade is used as the cleaning means for the intermediate transfer member.

9.
2. The electrophotographic image forming apparatus according to 1 above, wherein a lubricant application unit is provided after the electrophotographic photosensitive member cleaning unit.

10.
10. An electrophotographic photosensitive member used in the electrophotographic image forming apparatus according to any one of 1 to 9 above.

11.
The electrophotographic photosensitive member according to 10 above,
10. At least one unit selected from a charging unit, an exposure unit, a developing unit, a transfer unit, and a cleaning unit is combined and formed so as to be able to be inserted into and removed from the main body of the electrophotographic image forming apparatus according to any one of 1 to 9 above. An image forming unit.

  The image forming apparatus, photoconductor, and image forming unit of the present invention do not cause white spots in solid images or voids in character images, and black spots and fogging occur even when many sheets are printed. There is an excellent effect that a high-quality toner image can be continuously obtained without lowering or sharpness being lowered.

  The inventors of the present invention do not cause white spots in solid images or voids in character images. Black prints and fogging occur even when many sheets are printed, image density is low, and sharpness is reduced. An image forming apparatus capable of continuously obtaining a high-quality toner image without any trouble was investigated.

As a result of various studies, the surface layer of the photoreceptor contains particles having a number average primary particle diameter of 1 to 300 nm, the hardness (universal hardness) of the surface layer is adjusted to 200 to 350 N / mm ² , and the photoreceptor surface layer It has been found that the above problem can be solved by making the hardness (universal hardness) of the intermediate layer softer than the hardness of the surface layer of the intermediate transfer member used as transfer means.

  The reason is not clear, but when inorganic particles and organic particles are included as particles in the surface layer of the photoreceptor, the inorganic particles have the effect of preventing white spots in solid images and improving the transfer efficiency, It is presumed that the organic particles can easily leave the toner image and prevent the character image from being lost and prevent the resolution from being lowered due to the disturbance of the toner image during transfer.

  Also, by making the hardness of the surface layer of the photoconductor (universal hardness) softer than the hardness of the surface layer of the intermediate transfer member (universal hardness), the photoconductor and the intermediate transfer member are brought into contact with each other so that the toner image is transferred to the intermediate transfer member. It is presumed that the toner image is less disturbed during the transfer, and the toner image can be transferred to the intermediate transfer member while maintaining a high resolution.

  In addition, by including inorganic particles and organic particles as particles in the surface layer of the photoreceptor, the amount of wear by the cleaning member used on the surface as a cleaning means is reduced, and even if a large number of sheets are printed, black spots caused by wear are reduced. It is presumed that high-quality toner images can be continuously obtained without occurrence of fogging, reduction in image density, and reduction in sharpness.

  Furthermore, by using an elastic blade as the cleaning means, applying a lubricant to the surface of the photosensitive member, or adding a lubricant or abrasive as an external additive to the toner used in the developing means, the high quality toner can be continuously obtained. I guess it is possible to obtain images.

  Hereinafter, the present invention will be described in detail.

  First, the particle size of the particles will be described.

[Particle size]
The particles used in the present invention have a number average primary particle size of 1 to 300 nm, preferably 10 to 250 nm, and more preferably 30 to 200 nm.

  Here, the number average primary particle diameter is a value obtained by observing 100 particles as primary particles at random by 10000-fold observation with a transmission electron microscope and image analysis.

  Examples of the transmission electron microscope (TEM) include “H-9000NAR” (manufactured by Hitachi, Ltd.), “JEM-200FX” (manufactured by JEOL Ltd.), and the like.

  The observation method using a transmission electron microscope is performed by a normal method performed when measuring the particle size of the particles. For example, the procedure is as follows. First, materials for observation are prepared. After sufficiently dispersing the particles in a room temperature curable epoxy resin, the particles are embedded and cured to produce a block. The prepared block is cut into a thin piece having a thickness of 80 to 200 nm using a microtome equipped with diamond teeth to prepare a measurement sample. Next, the particles are magnified 10,000 times using a transmission electron microscope (TEM), and the particles are photographed. Next, the image information of 100 particles photographed by the image processing apparatus “Luzex F” (manufactured by Nicole) is arithmetically processed to obtain the number average primary particle diameter.

  Particles having a number average primary particle diameter in the above range can be uniformly dispersed in the binder, so that formation of aggregated particles and generation of large irregularities on the surface can be prevented. It is possible to form a good toner image without generation of transfer memory and generation of black spots due to the large unevenness. Further, the particles are less likely to settle in the coating solution, and the dispersion stability of the solution is also excellent.

  Next, the hardness (universal hardness) of the surface layer will be described.

[Hardness of surface layer (universal hardness)]
The photoreceptor used in the present invention has a surface layer hardness (universal hardness) of 200 to 350 N / mm ² and is softer than the surface layer of the intermediate transfer body used in the present invention.

  The surface hardness (universal hardness) can be measured using a surface coating property tester under the following conditions.

Measuring conditions Measuring machine: Hardness meter indentation testing machine H100V (manufactured by Fischer Instruments)
Measurement indenter: Vickers indenter Measurement environment: 20 ° C, 60% RH
Measurement sample: Cut the intermediate transfer member into a size of 5 cm x 5 cm to create a measurement sample Maximum test load: 2 mN
Weighting condition: The weight is applied in proportion to time at a speed that reaches the maximum test weight in 10 seconds.

Weighted creep time: 5 seconds In addition, the measurement measures 10 arbitrary places of a measurement sample, and makes the average value the hardness prescribed | regulated by universal hardness.

Next, the photoconductor will be described. [Photoconductor]
The photoreceptor used in the present invention is shown below.

  1. The surface layer of the photoreceptor contains particles having a number average primary particle size of 1 to 300 nm.

2. The surface layer hardness (universal hardness) of the photoreceptor is 200 to 350 N / mm ² . Preferably, it is 250-350 N / mm < ² >.

Incidentally, the hardness of the surface layer of the photosensitive member (universal hardness) is softer than the surface (parts) hardness of the intermediate transfer member, in particular it is preferably soft 20 N / mm ² or more, 25~80N / mm ² soft It is more preferable.

(Photoreceptor layer structure)
The photoreceptor used in the present invention contains particles having a number average primary particle diameter of 1 to 300 nm in the surface layer, and the hardness (universal hardness) of the surface layer may be 200 to 350 N / mm ² . The layer configuration is not particularly limited, and specific examples include the following configurations.

1) A structure in which a charge generation layer and a charge transport layer are sequentially laminated as a photosensitive layer on a conductive support;
2) A structure in which a charge generation layer, a charge transport layer, and a protective layer are sequentially laminated as a photosensitive layer on a conductive support;
3) A structure in which a single layer containing a charge transport material and a charge generation material is formed as a photosensitive layer on a conductive support;
4) A structure in which a single layer containing a charge transport material and a charge generation material and a protective layer are formed as a photosensitive layer on a conductive support;
5) A structure in which a charge transport layer and a charge generation layer are sequentially laminated as a photosensitive layer on a conductive support;
6) A structure in which a charge transport layer, a charge generation layer, and a protective layer are sequentially laminated as a photosensitive layer on a conductive support;
The photoconductor used in the present invention may have any of the above structures, but among these, those prepared by providing an intermediate layer, a charge generation layer, a charge transport layer, and a protective layer on a conductive substrate are preferable. .

  In the present invention, an intermediate layer can be provided between the conductive support and the photosensitive layer for the purpose of improving electrical characteristics and adhesiveness.

  Here, the surface layer of the photoreceptor is a layer in which the photoreceptor is in contact with the air interface. When an intermediate layer, a charge generation layer, and a charge transport layer are formed on the conductive support, the charge transport layer is formed. Is a surface layer, and when a protective layer is laminated on the charge transport layer, the protective layer is the surface layer.

  FIG. 1 is a schematic diagram showing an example of a layer structure of a photoreceptor used in the present invention.

  FIG. 1A shows a photoreceptor whose surface layer is a charge transport layer, and FIG. 1B shows a photoreceptor whose surface layer is a protective layer.

  In FIG. 1, 100 is a conductive substrate, 200 is an intermediate layer, 210 is inorganic particles, 220 is a binder, 300 is a photosensitive layer, 400 is a charge generation layer, 500 is a charge transport layer, 600 is a protective layer, and 700 is inorganic particles. , 800 represents organic particles, and 900 represents a surface layer.

<particle>
Since the particles having the number average primary particle size can be uniformly dispersed in the coating solution, formation of aggregated particles and generation of large irregularities on the surface can be prevented, and the aggregated particles serve as charge traps and black spots and transfer. It is possible to form a good toner image without occurrence of memory and black spots due to the large unevenness. Further, the particles are less likely to settle in the coating solution, and the dispersion stability of the solution is also excellent.

  In the present invention, the particles preferably include at least inorganic particles and organic particles.

  As for the ratio of an inorganic particle and an organic particle, 20-80 mass% of inorganic particles are preferable, and 30-70 mass is more preferable.

  Examples of the inorganic particles include those selected from silica particles, alumina particles, titanium dioxide particles, and strontium titanate particles. Of these, silica particles and alumina particles are preferred.

  The number average primary particle size of the inorganic particles is preferably 10 to 150 μm.

  The inorganic particles according to the present invention are preferably surface-treated from the viewpoint of improvement in dispersibility and stability of electrophotographic characteristics. For example, inorganic particles are added to a solution obtained by dissolving or suspending a reactive organosilicon compound in an organic solvent or water, and this solution is stirred for several minutes to about 1 hour. And depending on the case, after heat-processing this liquid, it passes through processes, such as filtration, and is dried, and the inorganic particle which coat | covered the surface with the organosilicon compound is obtained. A reactive organosilicon compound may be added to a suspension in which inorganic particles are dispersed in an organic solvent or water.

  The amount of the reactive organosilicon compound used for the surface treatment is 0.1 to 10 parts by weight of the reactive organosilicon compound with respect to 100 parts by mass of titanium oxide treated with the metal oxide in the charge amount during the surface treatment. 50 mass parts, More preferably, 1-10 mass parts is preferable. When the surface treatment amount is less than the above range, the surface treatment effect is not sufficiently imparted, and the dispersibility of the titanium oxide particles in the intermediate layer is deteriorated. Moreover, if the above range is exceeded, the electrical performance is deteriorated, resulting in an increase in residual potential and a decrease in charging potential.

  Examples of the reactive organosilicon compound include compounds represented by the following general formula (1), but the compound is not limited to the following compounds as long as it is a compound that undergoes a condensation reaction with a reactive group such as a hydroxyl group on the surface of the inorganic particles. .

General formula (1)
_{(R 1) n -Si- (X} 1) 4-n
(In the formula, Si represents a silicon atom, R ₁ represents an organic group in which carbon is directly bonded to the silicon atom, X ₁ represents a hydrolyzable group, and n represents an integer of 0 to 3.)
In the organosilicon compound represented by the general formula (1), the organic group in which carbon is directly bonded to the silicon represented by R ₁ includes methyl, ethyl, propyl, butyl, pentyl, hexyl, octyl, dodecyl and the like. Alkyl groups, aryl groups such as phenyl, tolyl, naphthyl, biphenyl, epoxy-containing groups such as γ-glycidoxypropyl, β- (3,4-epoxycyclohexyl) ethyl, γ-acryloxypropyl, γ-methacryloxy Propyl-containing (meth) acryloyl group, γ-hydroxypropyl, hydroxyl group such as 2,3-dihydroxypropyloxypropyl, vinyl-containing group such as vinyl and propenyl, mercapto group such as γ-mercaptopropyl, γ-aminopropyl Amino-containing groups such as N-β (aminoethyl) -γ-aminopropyl, γ-chloropropyl, Examples include halogen-containing groups such as 1,1,1-trifluoropropyl, nonafluorohexyl, perfluorooctylethyl, and other nitro and cyano-substituted alkyl groups. Examples of the hydrolyzable group for X ₁ include alkoxy groups such as methoxy and ethoxy, halogen groups, and acyloxy groups.

  Moreover, the organosilicon compound represented by the general formula (1) may be used alone or in combination of two or more.

Further, when n is 2 or more in the specific compound of the organosilicon compound represented by the general formula (1), a plurality of R ₁ may be the same or different. Similarly, when n is 2 or less, the plurality of X ₁ may be the same or different. Further, when the general formula (1) Organic silicon compound represented by the use of two or more, may be the same among R ₁ and X ₁ each compound may be different.

  Moreover, a hydrogenpolysiloxane compound is mentioned as a preferable reactive organosilicon compound used for surface treatment. The hydrogen polysiloxane compound having a molecular weight of 1000 to 20000 is generally easily available, and has a good function to prevent black spots. In particular, when methyl hydrogen polysiloxane is used, a good effect can be obtained.

  Another surface treatment of the inorganic particles according to the present invention is inorganic particles that have been surface treated with an organosilicon compound having a fluorine atom. The surface treatment with the organosilicon compound having a fluorine atom is preferably performed by the wet method described above.

  That is, an organic silicon compound having fluorine atoms in an organic solvent or water is dissolved or suspended, untreated inorganic particles are added thereto, and such a solution is stirred for several minutes to 1 hour and mixed. In some cases, after heat treatment, drying is performed through a process such as filtration, and the surfaces of the inorganic particles are coated with an organosilicon compound having a fluorine atom. The organosilicon compound having a fluorine atom may be added to a suspension in which inorganic particles are dispersed in an organic solvent or water.

  Examples of the organosilicon compound having a fluorine atom used in the present invention include 3,3,4,4,5,5,6,6,6-nonafluorohexyltrichlorosilane, 3,3,3-trifluoropropyltrimethoxy. Silane, methyl-3,3,3-trifluoropropyldichlorosilane, dimethoxymethyl-3,3,3-trifluoropropylsilane, 3,3,4,4,5,5,6,6,6-nonafluoro Examples include hexylmethyldichlorosilane.

  Other specific reactive organic titanium compounds used for the surface treatment of the inorganic particles include metal alkoxide compounds such as tetrapropoxy titanium and tetrabutoxy titanium, diisopropoxy titanium bis (acetyl acetate), and diisopropoxy titanium bis. Examples thereof include metal chelate compounds such as (ethyl acetoacetate), diisopropoxytitanium bis (lactate), dibutoxytitanium bis (octylene glycolate), and diisopropoxytitanium bis (triethanolaminate). Examples of the reactive organic zirconium compound include metal alkoxide compounds and metal chelate compounds such as tetrabutoxyzirconium and butoxyzirconium tri (acetyl acetate).

  Examples of the organic particles include those selected from fluorine atom-containing particles, polyolefin particles, polyester particles, and silicon atom-containing particles, and among these, fluorine atom-containing particle polyester particles are preferable.

  Examples of the fluorine atom-containing particles include ethylene tetrafluoride resin, ethylene trifluoride chloride resin, hexafluoroethylene propylene resin, vinyl fluoride resin, vinylidene fluoride resin, ethylene difluoride dichloride resin, and these It is preferable to appropriately select one or two or more types from among the copolymers, and particularly, a trifluoroethylene chloride resin, a tetrafluoroethylene resin, and a vinylidene fluoride resin are preferable.

  The number average primary particle size of the organic particles is preferably 20 to 250 μm.

  As for the ratio of the addition amount of an inorganic particle and an organic particle, 20-80 mass% is preferable for an inorganic particle, and 30-70 mass is more preferable.

[Hardness of surface layer of photoconductor (universal hardness)]
The hardness (universal hardness) of the surface layer of the photoreceptor can be adjusted by the resin forming the surface layer, the type of particles to be added, the particle size, the content, the layer forming method, and the like.

  Specifically, when increasing the hardness (universal hardness) of the surface layer of the photoreceptor, a large amount of inorganic particles with high hardness is added, or the resin forming the surface layer is cured to increase the hardness. Can do.

[Production of photoconductor]
The photoreceptor can be prepared by dip coating, circular amount regulation type coating, or a combination of dip coating and round amount regulation type coating, but is not limited to this. The circular amount regulation type application is described in detail in, for example, Japanese Patent Application Laid-Open No. 58-189061.

Next, members and layers constituting the photoreceptor according to the present invention will be described (conductive substrate).
The conductive substrate (conductive support) used in the present invention is preferably cylindrical and has a specific resistance of 10 ³ Ωcm or less. As a specific example, cylindrical aluminum whose surface has been cleaned after cutting can be mentioned.

(Middle layer)
The intermediate layer is formed by applying and drying an intermediate layer coating liquid composed of a binder, inorganic particles, a dispersion solvent, and the like on a conductive substrate.

  Examples of the binder for the intermediate layer include polyamide resins, vinyl chloride resins, vinyl acetate resins, and copolymer resins containing two or more of these resin repeating units. Among these resins, a polyamide resin is preferable because it can reduce a residual potential increase due to repeated use.

  As the solvent for preparing the intermediate layer coating solution, a solvent in which the inorganic particles to be added are well dispersed and the polyamide resin is dissolved is preferable. Specifically, alcohols having 2 to 4 carbon atoms such as ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol, t-butanol, sec-butanol and the like are excellent in solubility and coating performance of the polyamide resin. These solvents are 30 to 100% by mass, preferably 40 to 100% by mass, and more preferably 50 to 100% by mass in the total solvent. Examples of co-solvents that can be used in combination with the above-mentioned solvent to obtain preferable effects include methanol, benzyl alcohol, toluene, methylene chloride, cyclohexanone, and tetrahydrofuran.

  The thickness of the intermediate layer is preferably 0.2 to 40 μm, and more preferably 0.3 to 20 μm.

(Photosensitive layer)
The photosensitive layer may have a single layer structure in which a charge generation function and a charge transport function are provided in one layer, but more preferably the function of the photosensitive layer is separated into a charge generation layer (CGL) and a charge transport layer (CTL). It is more preferable to take a layer structure. By adopting a configuration in which the functions are separated, an increase in residual potential due to repeated use can be controlled to be small, and other electrophotographic characteristics can be easily controlled according to the purpose.
In the negatively charged photoreceptor, a charge generation layer (CGL) is formed on the intermediate layer, and a charge transport layer (CTL) is formed thereon. In the positively charged photoconductor, the order of the layer configuration is opposite to that in the negatively charged photoconductor. A preferred layer structure of the photosensitive layer is a negatively charged photoreceptor having the function separation structure.

  Hereinafter, each layer of the photosensitive layer of the function-separated negatively charged photoreceptor will be described.

<Charge generation layer>
The charge generation layer contains a charge generation material (CGM). Other substances may contain a binder resin and other additives as necessary.

  A known charge generation material (CGM) can be used as the charge generation material (CGM). For example, a phthalocyanine pigment, an azo pigment, a perylene pigment, an azulenium pigment, or the like can be used.

  When a binder is used as a CGM dispersion medium in the charge generation layer, a known resin can be used as the binder, but the most preferable resins include formal resin, butyral resin, silicon resin, silicon-modified butyral resin, phenoxy resin, and the like. Can be mentioned. The ratio of the binder resin to the charge generating material is preferably 20 to 600 parts by mass with respect to 100 parts by mass of the binder resin. By using these resins, the increase in residual potential associated with repeated use can be minimized. The thickness of the charge generation layer is preferably from 0.01 to 2 μm.

<Charge transport layer>
When the charge transport layer is a surface layer, the charge transport layer is formed from the particles according to the present invention, a charge transport material (CTM), and a binder resin. Other substances may be formed by adding additives such as antioxidants as necessary. The thickness of the charge transport layer is preferably 0.2 to 40 μm, and more preferably 0.3 to 20 μm.

  When the charge transport layer forms the surface layer, the amount of the particles according to the present invention in the charge transport layer is preferably 5 to 50% by mass, and more preferably 10 to 30% by mass.

  A known charge transport material (CTM) can be used as the charge transport material (CTM). For example, a triphenylamine derivative, a hydrazone compound, a styryl compound, a benzidine compound, a butadiene compound, or the like can be used.

  Examples of the resin used for the charge transport layer (CTL) include polystyrene, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, polyvinyl butyral resin, epoxy resin, polyurethane resin, phenol resin, polyester resin, alkyd resin, and polycarbonate. Resin, silicon resin, melamine resin, and copolymer resin containing two or more of repeating units of these resins. In addition to these insulating resins, polymer organic semiconductors such as poly-N-vinylcarbazole can be used.

  Most preferred as a binder for these CTLs is a polycarbonate resin. The polycarbonate resin is most preferable in improving the dispersibility and electrophotographic characteristics of CTM. The ratio of the binder resin to the charge transport material is preferably 10 to 200 parts by mass with respect to 100 parts by mass of the binder resin. The thickness of the charge transport layer is preferably 10 to 40 μm.

  As the antioxidant, a known compound can be used, and specifically, “Irganox 1010” (manufactured by Ciba Geigy Japan) can be mentioned.

(Protective layer)
The protective layer is formed by mixing the particles according to the present invention, a charge transport material, a wear-resistant resin, and a curable resin. Examples of the protective layer resin include polycarbonate resin, acrylic resin, phenol resin, epoxy resin, urethane resin, and siloxane resin.

  5-50 mass% is preferable and, as for the quantity of the particle | grains based on this invention which occupies in a protective layer, 10-30 mass% is more preferable.

  Next, the intermediate transfer member will be described.

[Intermediate transfer member]
The intermediate transfer member used in the present invention is characterized in that the hardness of the surface layer (universal hardness) is higher than the hardness (universal hardness) of the surface layer of the photoreceptor used in the present invention.

  By using an intermediate transfer member having a hardness higher than that of the photosensitive member, it is possible to transfer the toner image from the photosensitive member satisfactorily, to prevent toner filming, and to prevent the intermediate transfer member from being worn out.

  The surface hardness of the intermediate transfer member can be adjusted by the type of resin forming the surface layer of the intermediate member, the type and amount of additives added to the surface layer, and the like.

  The hardness (universal hardness) of the surface layer of the intermediate transfer member can be measured by the same measuring method as that for the photosensitive member.

The intermediate transfer member is preferably composed of a semiconductive belt substrate having a volume resistivity of 1 × 10 ⁴ to 1 × 10 ¹² Ωcm.

  Examples of the material constituting the belt substrate of the intermediate transfer member include resin materials such as thermosetting polyimide and modified polyimide, ethylene-propylene rubber (EPDM), acrylonitrile-butadiene rubber (NBR), chloroprene rubber (CR), and polyurethane rubber. Examples thereof include those obtained by dispersing conductive fillers such as carbon in rubber materials such as those containing ionic conductive materials.

  Next, toner and developer will be described.

〔toner〕
The toner used in the present invention is not particularly limited, but a toner prepared by adding lubricant particles (for example, aliphatic metal salt) and abrasive particles as external additives is preferable.

  Use of the toner is preferable because the surface of the photosensitive member and the surface of the intermediate transfer member can be easily cleaned, and cleaning residue and toner filming are less likely to occur.

  As the lubricant particles, those that have been suitably used conventionally can be used, and specific examples include zinc stearate and calcium stearate. The addition ratio of the lubricant particles is preferably 0.1 to 0.4% by mass with respect to the toner.

  As the abrasive particles, those that have been conventionally used can be used, and specific examples include inorganic particles such as silica particles, titanium dioxide particles, and barium sulfate particles. The addition ratio of the abrasive particles is preferably 0.1 to 1.0% by mass with respect to the toner.

(Developer)
As the developer used in the developing means, one that has been suitably used conventionally can be used, and specifically, a one-component developer or a two-component developer may be used.

  When used as a one-component developer, a non-magnetic one-component developer or a magnetic one-component developer containing about 0.1 to 0.5 μm of magnetic particles in the toner particles may be used. can do.

  Further, it can be mixed with a carrier and used as a two-component developer. In this case, as the magnetic particles of the carrier, materials that have been conventionally used more favorably such as metals such as iron, ferrite, and magnetite, and alloys of these metals with metals such as aluminum and lead can be used. Ferrite particles are particularly preferable. The magnetic particles preferably have a volume average particle diameter of 15 to 100 μm, more preferably 25 to 80 μm.

  The volume average particle diameter of the carrier can be typically measured by a laser diffraction particle size distribution measuring apparatus “HELOS” (manufactured by SYMPATEC) equipped with a wet disperser.

  Next, the image forming apparatus will be described.

[Image forming apparatus]
The image forming apparatus according to the present invention includes at least a charging unit that charges the surface of the photosensitive member, an exposure unit that exposes the charged photosensitive member to form an electrostatic latent image, and the electrostatic latent image on the photosensitive member with toner. Developing means for developing and forming a toner image, primary transfer means for transferring the toner image on the photosensitive member onto the intermediate transfer member, and two transfer means for transferring the toner image transferred onto the intermediate transfer member to the recording medium .

  In the image forming apparatus of the present invention, it is preferable to provide a cleaning unit for cleaning the intermediate transfer member and a unit for applying a lubricant to the surface of the photosensitive member in addition to the above units.

  FIG. 2 is a cross-sectional configuration diagram illustrating an example of the image forming apparatus of the present invention.

  This image forming apparatus is called a tandem color image forming apparatus, and includes a plurality of sets of image forming units 10Y, 10M, 10C, and 10K, an endless belt-shaped intermediate transfer body unit 7 as a transfer unit, and a recording medium P. An endless belt-shaped sheet feeding and conveying means 21 and a belt type fixing device 24 as a fixing means. A document image reading device SC is disposed on the upper part of the main body A of the image forming apparatus.

  As one of the different color toner images formed on each photoconductor, an image forming unit 10Y that forms a yellow image includes a drum-shaped photoconductor 1Y as a first image carrier, and the photoconductor 1Y. A charging unit 2Y, an exposure unit 3Y, a developing unit 4Y, a primary transfer roller 5Y as a primary transfer unit, and a cleaning unit 6Y are arranged around the periphery. In addition, an image forming unit 10M that forms a magenta image as another different color toner image is a drum-shaped photoconductor 1M as a first image carrier, and is arranged around the photoconductor 1M. The charging unit 2M, the exposure unit 3M, the developing unit 4M, the primary transfer roller 5M as the primary transfer unit, and the cleaning unit 6M are included. In addition, an image forming unit 10C that forms a cyan image as another different color toner image includes a drum-shaped photoconductor 1C as a first image carrier, and around the photoconductor 1C. A charging unit 2C, an exposure unit 3C, a developing unit 4C, a primary transfer roller 5C as a primary transfer unit, and a cleaning unit 6C are disposed. In addition, an image forming unit 10K that forms a black image as one of other different color toner images is disposed around a drum-shaped photoconductor 1K as a first image carrier and the photoconductor 1K. A charging unit 2K, an exposure unit 3K, a developing unit 4K, a primary transfer roller 5K as a primary transfer unit, and a cleaning unit 6K.

  The endless belt-like intermediate transfer body unit 7 includes an endless belt-like intermediate transfer body 70 as a second image carrier having a semiconductive endless belt shape that is wound around a plurality of rollers and is rotatably supported.

  Each color image formed by the image forming units 10Y, 10M, 10C, and 10K is sequentially transferred and synthesized on the rotating endless belt-shaped intermediate transfer body 70 by the primary transfer rollers 5Y, 5M, 5C, and 5K. A color image is formed. A recording medium P such as paper as a recording medium accommodated in the paper feeding cassette 20 is fed by the paper feeding / conveying means 21, passes through a plurality of intermediate rollers 22 A, 22 B, 22 C, 22 D, and a registration roller 23, and is secondary. A color image is transferred onto the recording medium P at a time by being conveyed to a secondary transfer roller 5A as a transfer means. The recording medium P onto which the color image has been transferred is fixed by the belt-type fixing device 24, is sandwiched between the paper discharge rollers 25, and is placed on a paper discharge tray 26 outside the apparatus.

  On the other hand, after the color image is transferred to the recording medium P by the secondary transfer roller 5A, the residual toner is removed by the cleaning unit 6A from the endless belt-shaped intermediate transfer body 70 in which the recording medium P is separated by curvature.

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

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

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

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

  The image forming units 10Y, 10M, 10C, and 10K are arranged in tandem in the vertical direction. An endless belt-shaped intermediate transfer body unit 7 is disposed on the left side of the photoreceptors 1Y, 1M, 1C, and 1K in the figure. The endless belt-shaped intermediate transfer body unit 7 includes an endless belt-shaped intermediate transfer body 70 that can be rotated by winding rollers 71, 72, 73, 74, and 76, primary transfer rollers 5Y, 5M, 5C, and 5K, and a cleaning unit 6A. It consists of.

  The image forming units 10Y, 10M, 10C, and 10K and the endless belt-shaped intermediate transfer body unit 7 are integrally pulled out from the main body A by the drawer operation of the housing 8.

  In this manner, toner images are formed on the photoreceptors 1Y, 1M, 1C, and 1K by charging, exposure, and development, and the toner images of the respective colors are superimposed on the endless belt-shaped intermediate transfer body 70, and are collectively recorded on the recording medium P. The image is transferred and fixed by a belt-type fixing device 24 by pressing and heating. The photoreceptors 1Y, 1M, 1C, and 1K after transferring the toner image to the recording medium P clean the toner remaining on the photoreceptor during transfer by the cleaning unit 6A, and then perform the above charging, exposure, and development cycle. The next image formation is performed.

The process speed of this image forming apparatus is 220 mm / s when A4 size is used, the primary transfer roller is a sponge roller having a resistance value of 1 × 10 ⁷ Ω and a diameter of 20 mm, and transfer control is constant voltage control. In the full color mode, as shown in the cross-sectional configuration diagram of FIG. 2, the photoreceptors 1Y, 1M, 1C, and 1K are mounted on the bases of the primary transfer rollers 5Y, 5M, 5C, and 5K via the endless belt-shaped intermediate transfer body 70. 5T slides in the guide 5G by the pin D and moves in the direction of the arrow A, and the spring S acts and is pressed by the primary transfer rollers 5Y, 5M, 5C, and 5K. In the mode, only the black photosensitive member 1K is pressed against the black primary transfer roller 5K via the endless belt-shaped intermediate transfer body 70. For Y, M, and C, the primary transfer rollers 5Y, 5M, and 5C By moving the base 5T in the direction of the arrow B by the pin D, the contact and pressing of the photoreceptors 1Y, 1M, and 1C, the endless belt-shaped intermediate transfer body 70, and the primary transfer rollers 5Y, 5M, and 5C are performed. It has been released.

  In the image forming apparatus, an elastic blade is used as a cleaning member of the cleaning unit 6A for cleaning the intermediate transfer member.

  Further, means (11Y, 11M, 11C, 11K) for applying a lubricant to each photoconductor is provided, and zinc stearate is used as the lubricant.

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

<< Production of photoconductor >>
<Preparation of Photoreceptor 1>
(Conductive substrate)
As the conductive substrate, a cylindrical aluminum substrate that had been subjected to cutting (processing to JISB-0601-specified 10-point surface roughness Rz: 0.81 μm) and then surface-cleaned was used.

(Formation of intermediate layer)
A liquid containing the following components is dispersed for 10 hours using a batch type sand mill disperser, then diluted twice with the same mixed solvent, and allowed to stand overnight. Filtration accuracy: 5 μm, pressure: 50 kPa) to prepare an intermediate layer coating solution.

Intermediate layer coating solution Polyamide resin (N-9) 1.0 part by mass Solvent 10.0 parts by mass
(Ethanol / n-propyl alcohol / tetrahydrofuran
= Mass ratio 5/2/3)

  The intermediate layer coating solution was adjusted to a penetration depth of the dip coating, applied from the upper end of the conductive substrate to 15 mm, and dried to form an intermediate layer coating film.

  Thereafter, the intermediate layer coating film from the lower end of the conductive substrate to 15 mm is removed with a tape impregnated with a solvent (ethanol / n-propyl alcohol / tetrahydrofura (mass ratio 5/2/3)) to remove the lower end of the conductive substrate. After the exposure, heat treatment was performed at 120 ° C. for 30 minutes to form an intermediate layer having a thickness of 3.0 μm. The film thickness is a value measured using an eddy current type film thickness measuring device “EDDY560C” (manufactured by HELMUT FISCHER GMBTE CO).

(Formation of charge generation layer)
A liquid in which the following components were mixed was dispersed using a sand mill disperser to prepare a charge generation layer coating liquid.

Charge generation layer coating liquid Y-type oxytitanyl phthalocyanine (X-ray diffraction spectrum by Cu-Kα characteristic X-ray, titanyl phthalosine pigment having a maximum diffraction peak at a Bragg angle (2θ ± 0.2 °) of 27.3 °) 20 parts by mass Silicon-modified polyvinyl butyral 10 parts by mass 4-methoxy-4-methyl-2-pentanone 700 parts by mass t-butyl acetate 300 parts by mass With this coating solution, the penetration depth of dip coating is adjusted, and the upper end of the conductive substrate A charge generation layer was formed by coating and drying from a portion up to 13 mm.

  Thereafter, the charge generation layer coating film from the lower end of the conductive substrate to 13 mm was removed with a tape impregnated with a solvent (4-methoxy-4-methyl-2-pentanone / t-butyl acetate (mass ratio 7/3)). The lower end of the conductive substrate was exposed, and a charge generation layer having a thickness of 0.3 μm was formed on the intermediate layer. The film thickness is a value measured using an eddy current type film thickness measuring device “EDDY560C” (manufactured by HELMUT FISCHER GMBTE CO).

(Formation of charge transport layer)
A liquid in which the following components are mixed is dispersed for 10 hours using a batch type sand mill disperser, and then filtered (filter; rigesh mesh filter manufactured by Nihon Pall Co., Ltd., nominal filtration accuracy: 5 μm, pressure: 50 kPa) and applied to a charge transport layer. A liquid was prepared.

Charge transport layer coating solution 4-methoxy-4 '-(4-methyl-α-phenylstyryl) triphenylamine
70 parts by mass Bisphenol Z-type polycarbonate “Iupilon-Z300” (Mitsubishi Gas Chemical Co., Ltd.) 100 parts by mass “Inorganic particles” Titanium dioxide particles (number average primary particle size 33 nm) 30 parts by mass “Organic particles” Polyester resin particles (number average) Primary particle diameter 70 nm) 45 parts by mass Antioxidant “Irganox 1010” (manufactured by Ciba Geigy Japan) 8 parts by mass Solvent (tetrahydrofuran / toluene (mass ratio 8/2)) 750 parts by mass The charge transport layer was formed by adjusting, applying and drying up to 10 mm from the upper end of the conductive substrate.

  Thereafter, the charge transport layer coating from the lower end of the conductive substrate to 10 mm is removed with a tape impregnated with a solvent (tetrahydrofuran / toluene (mass ratio 8/2)) to expose the lower end of the conductive substrate, and the charge generation layer A charge transport layer having a thickness of 25 μm was formed thereon. The film thickness is a value measured using an eddy current type film thickness measuring device “EDDY560C” (manufactured by HELMUT FISCHER GMBTE CO).

(Formation of protective layer)
The following components were dispersed and dissolved using a sand mill disperser to prepare a protective layer coating solution.

Protective layer coating solution 4-methoxy-4 '-(4-methyl-α-phenylstyryl) triphenylamine
50 parts by mass Bisphenol Z-type polycarbonate “Iupilon-Z800” (Mitsubishi Gas Chemical Co., Ltd.) 100 parts by mass “Inorganic particles” Titanium dioxide (number average primary particle size 33 nm) 35 parts by mass “Organic particles” Polyester resin particles (number average primary Particle size 70 nm) 45 parts by mass Antioxidant “Irganox 1010” (manufactured by Ciba Geigy Japan) 8 parts by mass Solvent (tetrahydrofuran / toluene (mass ratio 8/2)) 750 parts by mass Was coated on the charge generation layer with a circular amount-regulating coating device and dried to form a 6 μm-thick protective layer coating film to produce “Photoreceptor 1” (corresponding to FIG. 1B). The film thickness is a value measured using an eddy current type film thickness measuring device “EDDY560C” (manufactured by HELMUT FISCHER GMBTE CO).

The hardness (universal hardness) of the surface layer of the obtained photoreceptor was 200 N / mm ² .
The hardness of the surface layer (universal hardness) is a value obtained by measurement by the above method.

<Production of photoconductors 2 to 5 and 7 to 9>
The “inorganic particles” and “organic particles” used in the preparation of the charge transport layer and the protective layer of the “photoreceptor 1” were changed as shown in Table 1, and the same method as the production method of the “photoreceptor 1” was used. “Photosensitive members 2 to 5, 7, and 8” were produced (corresponding to (b) of FIG. 1).

<Preparation of Photoreceptor 6>
In “Preparation of Photoreceptor 1”, “Photoreceptor 6” was prepared in the same manner except that the charge transport layer was formed, the protective layer was not formed thereon, and the charge transport layer was used as the surface layer (see FIG. 1). (Corresponding to (a)).

  Table 1 shows the layer structure of “photosensitive members 1 to 9”, the types of inorganic particles and organic particle particles used for forming the charge transport layer and the protective layer, the number average primary particle diameter, and the ratio of the inorganic particles.

<Intermediate transfer member>
As the intermediate transfer member of the example, “intermediate transfer member 1” having an endless shape made of thermosetting polyimide, a resistance value of 1 × 10 ⁸ Ω, and a surface hardness (universal hardness) of 280 N / mm ² , and 390 N / An “intermediate transfer member 2” of mm ² was prepared. As a comparative example, an “intermediate transfer member 3” having a surface hardness (universal hardness) of 180 N / mm ² was prepared.

  In addition, the hardness of the intermediate transfer body of the examples was adjusted by the amount of silica particles added to the thermosetting polyimide and the thermosetting conditions.

<Preparation of intermediate transfer member>
Preparation of coating film forming liquid (Preparation of coating film forming liquid 1)
An equimolar amount of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (hereinafter abbreviated as BPDA) and p-phenylenediamine (hereinafter abbreviated as PDA) was determined as N-methylpyrrolidinone (hereinafter abbreviated as NMP). A polycondensation reaction was performed in the solution at 20 ° C. to synthesize 2 kg of an “aromatic polyamic acid solution” (solution viscosity: 4.1 Pa.s) having a solid content of 16% by mass.

In addition to 2 kg of the above-mentioned “aromatic polyamic acid solution”, 72 g of carbon black (pH 7, number average primary particle size 21 nm) as a conductive substance and 180 g of silica particles (number average primary particle size 28 nm, specific surface area 50 m ² / g) , Average circularity 0.9) and 462.4 g of N-methylpyrrolidinone as a diluent solvent, stir and mix using a three-one motor (manufactured by Shinto Kagaku Co., Ltd.), then transfer to a sand grinder and mix thoroughly Dispersion was performed to obtain “Coating Solution 1”.

(Preparation of intermediate transfer member 1)
A cylindrical coating head (not shown) is inserted into the inner surface of the cylindrical cylinder (mold) 91 of the centrifugal apparatus shown in FIG. 3, and while rotating the cylinder at 1000 rpm for 10 minutes with the rotating device 92, “coating” Forming liquid 1 ”was applied to the inner surface of the cylinder from the slit of the coating head to obtain a uniform coating layer.

  Next, the cylinder was heated to 150 ° C. by a heater 93, and solvent drying / curing reaction was performed for 30 minutes while rotating the cylinder at 250 rpm.

  Once returned to room temperature, the belt formed of the coating layer is extracted from the inner surface of the cylinder, and with the formwork set on the inner surface of the belt, the temperature is first raised to 200 ° C. at 10 ° C./min, and then 5 ° C. / After heating up to 380 degreeC at the speed | rate of min, it heated at 380 degreeC for 30 minutes, imide conversion was advanced and the surface layer was formed.

Then, the universal hardness of the belt obtained by cooling to room temperature and removing from a formwork was 280 N / mm < ² >. This belt was designated as “intermediate transfer member 1” having a film thickness of 85 μm.

(Preparation of intermediate transfer body 2)
An “intermediate transfer member 2” was produced in the same manner as the intermediate transfer member 1, except that the amount of silica particles of the “intermediate transfer member 1” was changed to 250 g and the rotation speed of the cylinder was changed to 1500 rpm. The universal hardness of “Intermediate transfer member 2” was 390 N / mm ² .

(Preparation of intermediate transfer member 3)
45.3 g of dried carbon black was added to 800 g of N-methyl-2-pyrrolidone (hereinafter abbreviated as NMP), and the mixture was stirred at room temperature for 6 hours using a ball mill. In the NMP dispersion, 140 g of BPDA as an acid component, 40 g of paraphenylenediamine and 30.0 g of 4,4-diaminodiphenyl ether as an amine component were dissolved and stirred at room temperature for 3 hours in a nitrogen atmosphere at 900 Pa.s. A polyamic acid of s (B-type viscometer, 25 ° C.) was obtained. Next, a solution consisting of 102 g of acetic anhydride as a dehydrating agent (equivalent to 2 mol), 12.9 g of isoquinoline as a catalyst (equivalent to 0.2 mol), and 150 g of NMP was added into this polyamic acid, and after stirring and mixing, Applied to the inner surface. Subsequently, it was rotated at 2000 rpm for 15 minutes to obtain a uniform coating surface. Next, hot air at 100 ° C. is applied for 10 minutes from the outside of the mold while rotating at 250 rpm, and then the solvent, dehydrating agent, and catalyst are removed by heating at 220 ° C. for 10 minutes and the maximum heating temperature at 300 ° C. for 30 minutes. Then, the imidization reaction was completed, the mold was cooled to room temperature, and the belt was peeled from the mold to obtain a semiconductive polyimide belt having a thickness of 55 μm. This belt was designated as “intermediate transfer member 3”, and its universal hardness was 180 N / mm ² .

<Developer>
The toner for the developer includes colored particles having a median particle diameter (D ₅₀ ) of 6 μm on a number basis, silica particles having a number average primary particle diameter of 50 nm, small titanium dioxide particles having a number average primary particle diameter of 20 nm, and calcium stearate. Was prepared by externally adding.

  A developer prepared by mixing a ferrite carrier having a number average primary particle size of 60 μm so that the toner concentration is 4% by mass was prepared.

  As the developing means, a two-component developing type developing device using the developer was used.

<Evaluation image forming apparatus>
According to the configuration of FIG. 2, “image forming apparatuses 1 to 3” were prepared. The specific device configuration is as follows.

<Image forming apparatus 1>
(1) The photosensitive member and the intermediate transfer member were used by sequentially attaching the “photosensitive members 1 to 9” and the “intermediate transfer members 1 to 3” produced as described above. (2) A scorotron charger was used as the charging means. (3) The exposure means used was a semiconductor laser irradiation apparatus having a surface standard output of 300 μW. (4) The development means used the “developer” produced above. (5) The primary transfer means was as described above. The prepared intermediate transfer member was used, and a transfer roller was used for transfer. (6) The secondary transfer means used the intermediate transfer member prepared above, and the transfer roller was used for transfer. (7) Intermediate transfer member The cleaning means used an elastic blade as a cleaning member. (8) The means for applying the lubricant to the photoreceptor used zinc stearate powder as the lubricant.

<Image forming apparatus 2>
An apparatus in which the elastic blade of the intermediate transfer member cleaning unit used in the image forming apparatus 1 is changed to a fur brush.

<Image forming apparatus 3>
An apparatus in which means for applying a lubricant to the photosensitive member is removed from the image forming apparatus 1.

《Image evaluation》
For the image evaluation, the above-mentioned “image forming apparatuses 1 to 3” are used, a character image with a pixel rate of 7% (characters of 3 points and 5 points), a human face photograph (dot images including halftones), a solid white image, An original image in which the solid black images were each divided into ¼ equal portions was performed with a toner image obtained by printing on neutral paper (64 g / m ² ) of A4 size.

(Blank image)
The original document was printed in a high temperature and high humidity (30 °, 85% RH) environment.

  The evaluation of the white spot of the solid image was determined by how many white spots having a major axis of 0.4 mm or more per A4 paper in the solid image portion. Incidentally, the hollow major axis was measured with a microscope equipped with a video printer.

Evaluation Criteria A: White spot frequency of 0.4 mm or more: All copied images are 3 / A4 or less. ○: White spot frequency of 0.4 mm or more: 4 / A4 or more, 19 / A4 or less occurs. ×: White spot frequency of 0.4 mm or more: One or more of 20 / A4 or more occurred.

(Cut out of text image)
The original document was printed in a low temperature and low humidity (10 °, 15% RH) environment.

  The three-point and five-point characters of the character image were enlarged and observed with a magnifying glass, and the occurrence of the void in the character image was visually evaluated.

Evaluation criteria ◎: Up to the 50,000th print, no 3 point or 5 point characters are missing. ○: Up to the 50,000th print, no 3 point characters are missing. ×: 50,000 sheets There is a noticeable dropout in the 3-point and 5-point characters printed on the eyes.

(Cover)
For fogging, the density of neutral paper (white paper) that has not been printed is measured at 20 locations and the absolute image density, the average value is taken as the white paper density, and then the white background portion of the neutral paper on which a solid image has been formed Similarly, measurement was performed at 20 positions at an absolute image density, and a value obtained by subtracting the white paper density from the average density was evaluated as a fog density. The measurement was performed using “RD-918” (Macbeth reflection densitometer).

Evaluation Criteria A: Good at 0.005 or less both at the initial stage and after printing 100,000 sheets ○: Level at 0.005 or less at the initial stage and 0.01 or less after printing 1,000,000 sheets No problem for practical use ×: Initial stage and 10 Both levels after printing 10,000 sheets are larger than 0.01 and cause practical problems.

(Black pot)
The black spots were evaluated after printing 100,000 sheets and printing 100 plain images. The evaluation was performed on the number of black spots per A4 plate that can be visually observed (diameter 0.4 mm or more) on the hard copy, where the periodicity of black spots coincides with the period of the photoreceptor.

Evaluation criteria ◎: Black hard spot occurrence frequency is 3 / A4 or less for all hard copies ○: Black stick occurrence frequency is 4 / A4 or higher and 10 / A4 or lower for all hard copies 1 or more occurs, but there is no practical problem. X: In all hard copies, the frequency of occurrence of black spots is 11 / A4 size or more, and there is a practical problem.

(Image density)
The image density was evaluated by the density of the solid black image portion of the print image. The image density was measured using “RD-918” (manufactured by Macbeth Co.), and the relative reflection density with the paper reflection density set to “0”.

Evaluation criteria ◎: Image density is 1.2 or higher in both initial and 1 million prints. ○: Initial image density is 1.2 or higher, and image density is 1.0 or higher after 1 million prints. Level where there is no problem ×: Image density is less than 1.0 both in the initial stage and after printing 1 million sheets.

(Sharpness)
The sharpness was evaluated by printing 1 million sheets, printing an original document, and observing a character image with a 10 × magnifier.

Evaluation criteria ◎: 3 points and 5 points are clear, easy to read and good ○: 3 points are partially unreadable, 5 points are clear, easily read and practically no problem ×: 3 The points are almost unreadable, and some or all of the 5 points are unreadable and practically problematic.

  Table 2 shows the evaluation results.

  From Table 2, it can be seen that "Examples 1 to 8" according to the present invention can obtain a high-quality toner image without any problem in any of the evaluation items. On the other hand, “Comparative Examples 1 to 3” for comparison shows that there is a problem in any of the evaluation items.

FIG. 2 is a schematic diagram illustrating an example of a layer configuration of a photoreceptor according to the present invention. 1 is a cross-sectional configuration diagram illustrating an example of an image forming apparatus of the present invention. It is a section lineblock diagram showing the principal part of a centrifugal forming device.

Explanation of symbols

100 substrate 200 intermediate layer 300 photosensitive layer 400 charge generation layer 500 charge transport layer 600 protective layer 700 inorganic particle 800 organic particle 900 surface layer 1Y, 1M, 1C, 1K photoreceptor 2Y, 2M, 2C, 2K charging means 3Y, 3M, 3C, 3K Exposure means 4Y, 4M, 4C, 4K Development means 5Y, 5M, 5C, 5K Primary transfer roller as primary transfer means 5A Secondary transfer roller as secondary transfer means 6Y, 6M, 6C, 6K Secondary transfer Body cleaning means 7 Endless belt-shaped intermediate transfer body unit 11Y, 11M, 11C, 11K Lubricant applying means 24 Fixing device

Claims (11)

At least a charging unit, an exposure unit, a developing unit that develops with a developer containing toner, a primary transfer unit that transfers a toner image formed by the developing unit onto the intermediate transfer member, and a toner on the intermediate transfer member. In an electrophotographic image forming apparatus having secondary transfer means for transferring an image to a recording medium,
The electrophotographic photoreceptor contains particles having a number average primary particle size of 1 to 300 nm on the surface layer thereof,
The surface layer has a hardness (universal hardness) of 200 to 350 N / mm ² ,
An electrophotographic image forming apparatus characterized by being softer than the hardness (universal hardness) of the surface layer of the intermediate transfer member. The electrophotographic image forming apparatus according to claim 1, wherein the particles include at least inorganic particles and organic particles. The electrophotographic image forming apparatus according to claim 1, wherein the inorganic particles are selected from silica particles, alumina particles, titanium dioxide particles, and strontium titanate particles. 3. The electrophotographic image forming apparatus according to claim 1, wherein the organic particles are selected from fluorine atom-containing resin particles, silicon atom-containing resin particles, polyolefin particles, and polyester particles. 4. . 2. The electrophotographic image forming apparatus according to claim 1, wherein the surface layer of the electrophotographic photosensitive member is a charge transport layer. 2. The electrophotographic image forming apparatus according to claim 1, wherein the surface layer of the electrophotographic photosensitive member is a protective layer. The electrophotographic image forming apparatus according to claim 1, wherein the toner contains at least lubricant particles and abrasive particles. 2. The electrophotographic image forming apparatus according to claim 1, wherein an elastic blade is used as a cleaning unit for the intermediate transfer member. 2. The electrophotographic image forming apparatus according to claim 1, wherein a lubricant application unit is provided after the cleaning unit of the electrophotographic photosensitive member. An electrophotographic photoreceptor used in the electrophotographic image forming apparatus according to claim 1. An electrophotographic photoreceptor according to claim 10;
The at least one means selected from a charging means, an exposure means, a developing means, a transfer means, and a cleaning means is combined, and can be inserted into and removed from the main body of the electrophotographic image forming apparatus according to any one of claims 1 to 9. An image forming unit which is formed.

Images