JP4461921B2 - Organic photoreceptor, process cartridge, and image forming apparatus - Google Patents

Description

  The present invention relates to an organic photoreceptor (hereinafter also simply referred to as a photoreceptor), a process cartridge, and an image forming apparatus used for electrophotographic image formation, and more particularly, to an electrophotographic system used in the field of copying machines and printers. The present invention relates to an organic photoreceptor used for image formation, a process cartridge, and an image forming apparatus.

  In recent years, organic photoconductors containing organic photoconductive materials have been most widely used as electrophotographic photoconductors. Organic photoconductors have advantages over other photoconductors, such as easy development of materials suitable for various exposure light sources from visible light to infrared light, the ability to select materials without environmental pollution, and low manufacturing costs. However, the mechanical strength is weak, and the surface of the photoconductor is greatly worn when copying or printing a large number of sheets.

  As a problem for improving the durability of the organic photoreceptor as described above, it has been strongly demanded to suppress wear due to abrasion of a cleaning blade or the like. As an approach for this, techniques such as installing a high-strength protective layer on the surface of the photoreceptor have been studied. For example, it has been reported that a colloidal silica-containing curable siloxane resin is used as a surface layer of a photoreceptor (Patent Document 1). In addition, an organic photoreceptor containing hydrophobic silica in the surface layer and having a surface roughness Ra of 0.02 μm or more and less than 0.1 μm and an Rz of 0.1 μm or more and less than 1 μm has been reported (Patent Document 2). However, a photoconductor having a protective layer containing such inorganic particles has improved mechanical wear resistance, but with such surface roughness, NOx and Active gases such as ozone are likely to be adsorbed, causing problems such as deterioration of charging stability during repeated use, an increase in residual potential, and fog and image blurring.

  Furthermore, recent copying machines, printers, and the like have become mainstream digital image formation using a laser or light emitting diode as an exposure light source, and are required to form high-definition dot images.

However, with conventional organic photoconductors with a protective layer using silica or the like, dot images cannot be reproduced precisely due to deterioration of electrophotographic characteristics and image blurring caused by repeated use, and tone reproducibility is important In a printed image of a photographic image, a sufficiently satisfactory dot image could not be obtained.
Japanese Patent Laid-Open No. 6-118681 Japanese Patent Laid-Open No. 2003-316036

  The present invention improves the anti-wear characteristics of an organic photoconductor, and prevents image blurring and dot image deterioration due to adsorption of ozone and nitrogen oxides to the organic photoconductor, resulting in an electrophotographic image having good sharpness. The present invention provides an organic photoreceptor capable of producing a process cartridge, and a process cartridge and an image forming apparatus using the organic photoreceptor.

As a result of intensive studies, the present inventors have conducted detailed studies on the above-mentioned problems of the conventional organic photoreceptor using silica as a surface layer in order to solve the above-described problems of the present invention. By making the surface roughness of the surface layer containing the surface roughness less rough, it is possible to prevent deterioration of image blur and dot images, and to obtain an organic photoreceptor having stable potential characteristics against repeated use. The present invention has been completed. That is, the present invention is achieved by having any of the following configurations.
(Claim 1)
In an organic photoreceptor having at least an intermediate layer and a photosensitive layer on a conductive support, the ten-point surface roughness Rz of the conductive support is 0.1 to 1.0 μm, and the number average primary particle size is 3 to 3. having a surface layer containing inorganic particles 150 nm, the surface roughness Ra of 0.001～0.018Myuemu, and ten-point surface roughness Rz Ri 0.02~0.08μm der, of the intermediate layer organic photoreceptor having a thickness and wherein 1~10μm der Rukoto.
(Claim 2)
In an image forming apparatus having an image exposure means for forming an electrostatic latent image on an organic photoreceptor having at least an intermediate layer and a photosensitive layer on a conductive support using an exposure beam having an exposure spot area of 2000 μm ² or less. The conductive support has a 10-point surface roughness Rz of 0.1 to 1.0 μm, a surface layer containing inorganic particles having a number average primary particle size of 3 to 150 nm, and a surface roughness Ra of 0. in .001～0.018Myuemu, and ten-point surface roughness Rz Ri 0.02~0.08μm der, an image forming apparatus thickness of the intermediate layer is characterized 1~10μm der Rukoto.
(Claim 3)
The organophotoreceptor according to claim 1, wherein the inorganic particles are a metal oxide.
(Claim 4)
The organophotoreceptor according to claim 1, wherein the inorganic particles are silica particles.
(Claim 5)
The organophotoreceptor according to claim 1, wherein the inorganic particles have a hydrophobicity of 50 or more and a hydrophobicity distribution value of 25 or less.
(Claim 6)
The organophotoreceptor according to claim 1, wherein the surface layer contains an antioxidant.
(Claim 7)
The organic photoreceptor according to claim 1, wherein the surface layer contains a polycarbonate resin.
(Claim 8)
The organic photoreceptor according to claim 1 , wherein the intermediate layer contains N-type semiconductor particles .
(Claim 9)
The organophotoreceptor according to claim 8, wherein the N-type semiconductor particles are a metal oxide.
(Claim 10)
The organophotoreceptor according to claim 8 or 9, wherein the N-type semiconductor particles are titanium oxide or zinc oxide.
(Claim 11)
The organophotoreceptor according to claim 10, wherein the N-type semiconductor particles are titanium oxide.
(Claim 12)
The organophotoreceptor according to claim 11, wherein the titanium oxide is a rutile titanium oxide pigment or an anatase titanium oxide pigment.
(Claim 13)
The organophotoreceptor according to claim 8, wherein the N-type semiconductor particles are subjected to a surface treatment.
(Claim 14)
The organic photoreceptor according to claim 8, wherein the intermediate layer contains a binder of polyamide resin.
(Claim 15)
The organophotoreceptor according to claim 14, wherein the polyamide resin is a polyamide resin having a heat of fusion of 0 to 40 J / g and a water absorption of 5% by mass or less.
(Claim 16)
16. The organic photoreceptor according to claim 14, wherein the volume ratio of the binder resin and the N-type semiconductor particles in the intermediate layer is N-type semiconductor particles 1 to 2 with respect to the binder resin 1.
(Claim 17)

An organic photoreceptor, charging means for charging the organic photoreceptor, latent image forming means for forming an electrostatic latent image on the charged organic photoreceptor, developing means for developing the electrostatic latent image into a toner image, Transfer means for transferring the visualized toner image onto the transfer material from the organic photoreceptor, charge eliminating means for removing the charge on the organic photoreceptor after transfer, and residual toner on the organic photoreceptor after transfer are removed. A process cartridge for use in an image forming apparatus having a cleaning unit, wherein the organic photoreceptor and the charging unit, the latent image forming unit, the developing unit, the transfer unit, the charge eliminating unit, A process cartridge which is integrally supported with at least one of cleaning means and can be detachably attached to an image forming apparatus main body.
(Claim 18)
An organic photoreceptor, charging means for charging the organic photoreceptor, latent image forming means for forming an electrostatic latent image on the charged organic photoreceptor, developing means for developing the electrostatic latent image into a toner image, Transfer means for transferring the visualized toner image onto the transfer material from the organic photoreceptor, charge eliminating means for removing the charge on the organic photoreceptor after transfer, and residual toner on the organic photoreceptor after transfer are removed. An image forming apparatus having a cleaning unit, wherein the organic photoreceptor according to any one of claims 1 and 3 to 16 is used.

  By using the organophotoreceptor of the present invention, it is possible to achieve wear resistance suitable for long-term use, and prevent image blur and dot image degradation that occurred when silica particles were used in the surface layer, sharpness and An electrophotographic image with good gradation can be provided.

  Hereinafter, the present invention will be described in detail.

The organic photoreceptor of the present invention is an organic photoreceptor having at least a photosensitive layer on a conductive support , wherein the conductive support has a ten-point surface roughness Rz of 0.1 to 1.0 μm and a number average primary. It has a surface layer containing inorganic particles having a particle size of 3 to 150 nm, surface roughness Ra is 0.001 to 0.018 μm , and ten-point surface roughness Rz is 0.02 to 0.08 μm. It is characterized by that.

The organic photoreceptor of the present invention is an image exposure means for forming an electrostatic latent image on an organic photoreceptor having at least a photosensitive layer on a conductive support using an exposure beam having an exposure spot area of 2000 μm ² or less. In the organic photoreceptor used in the image forming apparatus having the above, the conductive support contains inorganic particles having a ten-point surface roughness Rz of 0.1 to 1.0 μm and a number average primary particle size of 3 to 150 nm. The surface roughness Ra is 0.001 to 0.018 μm , and the ten-point surface roughness Rz is 0.02 to 0.08 μm .

  The organophotoreceptor of the present invention has the above-described configuration, which is easy to occur in a photoreceptor containing inorganic particles such as silica in the surface layer, prevents image blurring and dot image deterioration, is highly durable, An electrophotographic image with good sharpness can be formed.

  Hereinafter, the structure of the organic photoreceptor of the present invention will be described.

The organic photoreceptor of the present invention is an organic photoreceptor having at least a photosensitive layer on a conductive support , wherein the conductive support has a ten-point surface roughness Rz of 0.1 to 1.0 μm and a number average primary. It has a surface layer containing inorganic particles having a particle size of 3 to 150 nm, surface roughness Ra is 0.001 to 0.018 μm , and ten-point surface roughness Rz is 0.02 to 0.08 μm. It is characterized by that.

  First, surface roughness Ra (hereinafter also simply referred to as Ra) and ten-point surface roughness Rz (hereinafter also simply referred to as Rz) will be described (same as JIS B 0601).

  In the present invention, Ra is extracted from the roughness curve by the reference length in the direction of the average line, the X-axis is taken in the direction of the average line of the extracted portion, the Y-axis is taken in the direction of the vertical magnification, and the roughness curve is taken as y. When the value is expressed by = f (x), the value obtained by the following formula is expressed in micrometers (μm).

  l is a reference length. In the present invention, l is 2.5 mm and the cutoff value is 0.08 mm.

Ten-point surface roughness Rz
Rz of the present invention is the difference between the average height of the top five peaks and the average height of the bottom five valleys over a distance of a reference length of 2.5 mm.

  The measuring instrument was a surface roughness meter (Surfcoder SE-30H manufactured by Kosaka Laboratory Ltd.). However, other measuring devices may be used as long as the measuring device produces the same result within the error range.

Surface roughness measurement conditions Measurement speed (Drive speed: 0.1 mm / sec)
Measuring needle diameter (Stylus: 2 μm)
The photoreceptor of the present invention has a surface layer containing inorganic particles having a number average primary particle size of 3 to 150 nm, and further has a surface roughness Ra of 0.001 to 0.018 and a ten-point surface. The roughness Rz is 0.02 to 0.08 μm.

  The surface layer of the present invention means a layer in contact with the air interface of the organic photoreceptor formed in a layer structure, and the layer is a protective layer, a charge transport layer, or a function as a function. It may be a layer having other functions.

  The inorganic particles of the present invention are preferably metal oxides (including transition metal oxides) such as silica, titanium oxide, zinc oxide, and alumina. Of these, silica, titanium oxide, and alumina are preferably used.

  In the present invention, fine particles having a number average primary particle diameter of inorganic particles in the range of 3.0 to 150 nm are used. Particularly, 5 nm to 100 nm is preferable. The number average primary particle diameter is a measured value as the average diameter in the ferret direction by image analysis by magnifying fine particles 10,000 times by transmission electron microscope observation, randomly observing 100 particles as primary particles.

  Inorganic particles having a number average primary particle size of less than 3.0 nm are difficult to uniformly disperse in the surface layer, tend to form aggregated particles, and Ra and Rz tend to be larger than the range of the present invention. Particles serve as charge traps and increase the residual potential, which tends to cause a decrease in image density, image blur, and dot image degradation. On the other hand, inorganic particles having a number average primary particle size larger than 150 nm tend to make large irregularities on the surface layer, Ra and Rz tend to be larger than the range of the present invention, and active gases (such as ozone and NOx) is likely to adhere, and image blurring and dot image degradation are likely to occur. In addition, inorganic particles having a number average primary particle size larger than 150 nm are likely to precipitate in the dispersion and easily generate aggregates.

  If the surface roughness Ra is less than 0.001 or the ten-point surface roughness Rz is less than 0.02, it is difficult to contain inorganic particles in an effective amount in the surface layer of the photoreceptor, and the resistance of the photoreceptor is reduced. Abrasion tends to be insufficient.

The value of Rz is influenced by the surface roughness of the conductive support of the organic photoreceptor in addition to the particle size and content of the inorganic particles in the surface layer. To achieve the range of Rz of the present invention, together with use of the inorganic particles, you the Rz of the conductive support from 0.1 to 1.0 .mu.m.

  Furthermore, as the inorganic particles to be contained in the surface layer, it is preferable to use inorganic particles which have been subjected to a surface treatment and have a degree of hydrophobicity defined below of 50 and a hydrophobicity distribution value of 25 or less.

  That is, since these inorganic particles have a large number of hydroxyl groups on the surface, it is known that these hydroxyl groups are blocked to increase the degree of hydrophobicity. It was found that image blurring and dot image deterioration cannot be prevented only by managing the degree of hydrophobicity indicating the blocking level, and the inorganic particles having a degree of hydrophobicity of 50 or more and a hydrophobicity distribution value controlled to 25 or less Is preferably used. By using such inorganic particles, image blurring and dot image deterioration can be prevented, and an electrophotographic image having high durability and good sharpness can be formed.

  If the degree of hydrophobicity of the inorganic particles is less than 50, there are many hydroxyl groups present on the surface of the inorganic particles, the potential characteristics (charging potential, residual potential, etc.) are highly dependent on humidity, and image blurring and dot image degradation occur. It's easy to do. The hydrophobicity of the inorganic particles is more preferably 55 or more. Also, inorganic particles having many hydroxyl groups on the surface, such as silica and titanium oxide, need to block almost 100% of these hydroxyl groups by surface treatment in order to increase the degree of hydrophobicity to 95% or more. High and impractical. From the viewpoint of production cost and practicality, the degree of hydrophobicity is more preferably 90% or less.

  On the other hand, when the hydrophobicity distribution value is larger than 25, inorganic particles having a large amount of hydroxyl groups remaining on the surface are included, and image blurring or dot image deterioration is likely to occur.

  The degree of hydrophobicity (methanol wettability) is a measure of wettability with methanol. That is, it is defined as follows.

Hydrophobicity (methanol wettability) = (a / (a + 50)) × 100
The method for measuring the degree of hydrophobicity is described below.

  0.2 g of inorganic particles to be measured are weighed and added to 50 ml of distilled water in a 200 ml beaker. Methanol is slowly added dropwise from a burette whose tip is immersed in a liquid until the entire inorganic particles are wetted (until they all settle) in a state of slow stirring. When the amount of methanol necessary to wet the entire inorganic particles is a (ml), the degree of hydrophobicity is calculated by the above formula.

Measuring method of hydrophobicity distribution value 1) Weigh 0.2 g of inorganic particles to be measured and put into a centrifuge tube.

(Prepare one for each point you want to plot)
2) Put methanol solutions of different concentrations into each 7 ml centrifuge tube with Komagome pipette and tighten (use the methanol concentration determined by the above hydrophobization degree for total precipitation).

  3) Disperse at 90 rpm with a tumbler mixer for 30 seconds.

4) Centrifuge (3500 rpm, 10 minutes)
5) Read the sedimentation volume, and determine each sedimentation volume% when the total sedimentation volume (the total sedimentation volume) is 100%.

  6) Based on each measured value, a graph of the amount of methanol on the horizontal axis (Vol%) and the volume of sedimentation on the vertical axis (%) is prepared.

  The hydrophobicity distribution value is calculated from the above measurement.

  The hydrophobicity distribution value of 25 or less is defined as follows.

{(Methanol Vol.% With a sedimentation volume of 100%)
-(Methanol Vol.% With a sedimentation volume of 10%)} ≦ 25
The hydrophobization degree distribution curve is shown in FIG. In the distribution curve of FIG. 4, the methanol concentration at point a represents the degree of hydrophobicity, the difference between the methanol concentration at point a and the methanol concentration at point b; Δ (ab) represents the hydrophobicity distribution value of the present invention. .

  In order to produce inorganic particles having a degree of hydrophobicity and a degree of hydrophobicity distribution within the range of the present invention, the surface of silica or the like can be produced by surface treatment using a trimethylsilylating agent. In particular, it is preferable to use a trimethylsilylating agent represented by the following general formula (1) or general formula (2).

General formula (1)
((CH ₃ ) ₃ Si) ₂ NR
(In general formula (1), R is hydrogen or a lower alkyl group)
General formula (2)
(CH ₃ ) ₃ SiY
[In General Formula (2), Y is a group selected from a halogen atom, —OH, —OR ′, or —NR ′ ₂ (R ′ is the same as R in General Formula (1))]. The compounds shown are preferred. Here, in the above compound, the lower alkyl group of R is preferably a group having 1 to 5 carbon atoms such as a methyl group, an ethyl group or a propyl group, preferably 1 to 3 carbon atoms, particularly preferably a methyl group. Examples of the halogen atom for Y include chlorine, fluorine, bromine, iodine and the like, and chlorine is particularly preferable.

  Examples of the trimethylsilylating agent represented by the general formula (1) include hexamethyldisilazane, N-methyl-hexamethyldisilazane, N-ethyl-hexamethyldisilazane, hexamethyl-N-propyldisilazane and the like. It is particularly preferable to use hexamethyldisilazane because of its good reactivity.

  On the other hand, examples of the trialkylsilylating agent represented by the general formula (2) include trimethylchlorosilane, trimethylsilanol, methoxytrimethylsilane, ethoxytrimethylsilane, propoxytrimethylsilane, dimethylaminotrimethylsilane, and diethylaminotrimethylsilane. It is particularly preferable to use trimethylsilanol because of its good reactivity.

  As a surface treatment method, it is preferable to react silica and a trimethylsilylating agent in the presence of water vapor. In this reaction, the surface treatment is preferably performed at a partial pressure of the water vapor of 4 to 20 kPa, preferably 5 to 15 kPa.

  Here, when the water vapor partial pressure is less than 4 kPa, the degree of hydrophobicity does not increase, and the distribution of the degree of hydrophobicity also widens. On the other hand, even if the water vapor partial pressure is higher than 20 kPa, the distribution of the degree of hydrophobicity is widened, and the uniformity thereof tends to be impaired.

  The reaction between the silica and the trimethylsilylating agent is carried out when the silica having a higher degree of hydrophobicity is obtained in a short reaction time, and the partial pressure of the gas phase of the trimethylsilylating agent is 50 to 200 kPa, preferably 80 to 150 kPa. It is preferable to carry out under such a condition.

  Furthermore, the above reaction may be carried out in an atmosphere consisting only of a trimethylsilylating agent and water vapor. However, it is common to dilute these with an inert gas such as nitrogen or helium for use in the reaction. It is. In that case, the total pressure in the reaction atmosphere is generally 150 to 500 kPa, preferably 150 to 250 kPa.

  In order to further increase the reactivity between silica and the trimethylsilylating agent, a basic gas such as ammonia, methylamine or dimethylamine, preferably ammonia may be present in the reaction atmosphere as necessary. The partial pressure of such basic gas is preferably 1 to 100 kPa.

  The reaction temperature between silica and the trimethylsilylating agent is preferably 130 to 300 ° C, and preferably 150 to 250 ° C, taking into account the good reactivity of the hydrophobization reaction and the risk of decomposition of the trimethylsilylating agent. In general, the higher the reaction temperature in the above range, the higher the hydrophobicity of the resulting silica.

  When a polyfunctional silylating agent other than the trimethylsilylating agent or a trialkylsilylating agent having a high carbon number is used, the degree of hydrophobization tends to be low or the degree of hydrophobicity distribution tends to be large.

  The surface layer contains a binder resin that helps dispersibility of the inorganic particles. As the binder resin, polycarbonate and polyarylate are preferable. The molecular weight of these polycarbonates and polyarylates is preferably 10,000 to 100,000.

  The ratio of the inorganic particles in the surface layer is preferably at least 5 parts by mass and not more than 50 parts by mass with respect to 100 parts by mass of the binder resin. If the amount is less than 5 parts by mass, the surface layer is greatly worn, and scratches or the like are generated, so that the halftone image tends to be rough. When the amount is more than 50 parts by mass, the surface layer becomes a fragile film, and cracks and the like are likely to occur.

  The surface layer of the present invention preferably contains a charge transport material. As the charge transport material (CTM), a known hole transport property (P-type) charge transport material (CTM) is preferably used. For example, a triphenylamine derivative, a hydrazone compound, a styryl compound, a benzidine compound, a butadiene compound, or the like can be used. These charge transport materials are usually dissolved in a suitable binder resin to form a layer.

  The mass ratio of the binder resin and the charge transport material in the surface layer is preferably 30 to 200 parts by mass, and more preferably 50 to 150 parts by mass with respect to 100 parts by mass of the binder.

  The surface layer preferably contains an antioxidant. By containing the antioxidant and the inorganic particles of the present invention in the surface layer, it is possible to prevent fluctuations in the characteristics of the surface layer during repeated use, prevent image blurring and dot image deterioration, and provide a good electrophotographic image. Can be provided. Typical examples of the antioxidants prevent or suppress oxidation of auto-oxidizing substances existing in or on the surface of an organic photoreceptor under conditions such as light, heat, and discharge. It is a substance with the property to do.

  The antioxidant of the present invention is a substance having the property of preventing or suppressing the action of oxygen under conditions of light, heat, discharge, etc., against an auto-oxidizing substance present in the photoreceptor or on the photoreceptor surface. It is. Specifically, the following compound groups can be mentioned.

(1) Radical chain inhibitor ・ Phenol antioxidant (hindered phenol)
・ Amine antioxidants (hindered amines, diallyldiamines, diallylamines)
・ Hydroquinone antioxidant (2) Peroxide decomposer ・ Sulfur antioxidant (thioethers)
・ Phosphoric antioxidants (phosphites)
Among the above antioxidants, the radical chain inhibitor (1) is good, and a hindered phenol-based or hindered amine-based antioxidant is particularly preferable. Two or more types may be used in combination, for example, a combination of (1) a hindered phenol antioxidant and (2) a thioether antioxidant. Furthermore, the above-mentioned structural unit, for example, a hindered phenol structural unit and a hindered amine structural unit may be included in the molecule.

  Among the antioxidants, hindered phenol-based and hindered amine-based antioxidants are particularly effective in preventing fogging and image blurring at high temperatures and high humidity.

  The content of the hindered phenol-based or hindered amine-based antioxidant in the surface layer is preferably 0.01 to 20% by mass. When the content is less than 0.01% by mass, spots tend to occur. When the content exceeds 20% by mass, the charge transport ability in the surface layer decreases, the residual potential tends to increase, and the film strength decreases. Scratches are likely to occur.

  Here, hindered phenol refers to compounds having a branched alkyl group at the ortho position relative to the hydroxyl group of the phenol compound and derivatives thereof (however, the hydroxyl group may be converted to alkoxy).

  The hindered amine system is a compound having a bulky organic group near the N atom. The bulky organic group includes a branched alkyl group, for example, a t-butyl group is preferable. For example, compounds having an organic group represented by the following structural formula are preferred.

In the formula, R ₁₃ represents a hydrogen atom or a monovalent organic group, R ₁₄ , R ₁₅ , R ₁₆ and R ₁₇ represent an alkyl group, and R ₁₈ represents a hydrogen atom, a hydroxyl group or a monovalent organic group.

  Examples of the antioxidant having a hindered phenol partial structure include compounds described in JP-A-1-118137 (P7 to P14), but the present invention is not limited thereto.

  Examples of the antioxidant having a hindered amine partial structure include compounds described in JP-A-1-118138 (P7 to P9), but the present invention is not limited thereto.

  As an organic phosphorus compound, there exist the following as a typical thing with the compound represented by general formula: RO-P (OR) -OR, for example. Here, R represents a hydrogen atom, each substituted or unsubstituted alkyl group, alkenyl group or aryl group.

  As an organic sulfur type compound, there exist the following as a typical thing with the compound represented by general formula: R-S-R, for example. Here, R represents a hydrogen atom, each substituted or unsubstituted alkyl group, alkenyl group or aryl group.

  The following are examples of typical antioxidant compounds.

  Further, as the antioxidants that have been commercialized, the following compounds, for example, “Irganox 1076”, “Irganox 1010”, “Irganox 1098”, “Irganox 245”, “Irganox 245” as hindered phenols, are used. Knox 1330 "," Irganox 3114 "," Irganox 1076 "," 3,5-di-t-butyl-4-hydroxybiphenyl ", hindered amine series" Sanol LS2626 "," Sanol LS765 "," Sanol LS770 " , “Sanol LS744”, “Tinuvin 144”, “Tinuvin 622LD”, “Mark LA57”, “Mark LA67”, “Mark LA62”, “Mark LA68”, “Mark LA63”. TPS "," Sumi Iser TP-D ", and the phosphite system is" Mark 2112 "," Mark PEP-8 "," Mark PEP-24G "," Mark PEP-36 "," Mark 329K "," Mark HP-10 " Is mentioned.

  The present invention is an organic photoreceptor having a surface layer as described above. The constitution of the organic photoreceptor other than the surface layer will be described below.

  In the present invention, the organic photoconductor means an electrophotographic photoconductor constituted by providing an organic compound with at least one of a charge generation function and a charge transport function essential to the configuration of the electrophotographic photoconductor. All known organic photoconductors such as a photoconductor composed of an organic charge generating material or an organic charge transport material, a photoconductor composed of a polymer complex with a charge generating function and a charge transport function are contained.

The constitution of the organophotoreceptor of the present invention is not particularly limited as long as it has the surface layer according to the above-mentioned claim (1) or (2), and examples thereof include the following constitutions;
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 charge generation layer, a first charge transport layer and a second charge transport layer are formed as a photosensitive layer on a conductive support. Sequentially stacked configuration;
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 charge transport layer and a charge generation layer are sequentially laminated as a photosensitive layer on a conductive support;
5) A structure in which a surface protective layer is further formed on the photosensitive layer of the photoreceptors 1) to 5) above.

  The photoconductor may have any of the above configurations. The surface layer of the photoreceptor is a layer in contact with the air interface. When only a single-layer photosensitive layer is formed on the conductive support, the photosensitive layer is the surface layer, and the conductive layer In the case where a single-layered or laminated photosensitive layer and a surface protective layer are laminated on the conductive support, the surface protective layer is the outermost surface layer. In the present invention, the configuration 2) is most preferably used. Note that, regardless of the configuration of the photoreceptor of the present invention, an undercoat layer (intermediate layer) may be formed on the conductive support prior to the formation of the photosensitive layer.

  The charge transport layer means a layer having a function of transporting charge carriers generated in the charge generation layer by photoexposure to the surface of the organic photoreceptor, and the specific detection of the charge transport function is carried out between the charge generation layer and the charge transport layer. It can be confirmed by laminating a transport layer on a conductive support and detecting optical conductivity.

  Next, the layer structure of the organic photoreceptor will be described focusing on the structure of 2) above.

Conductive Support The conductive support used for the photoreceptor may be either a sheet or a cylinder, but a cylindrical conductive support is preferred for designing an image forming apparatus compactly. .

  Cylindrical conductive support means a cylindrical support necessary for forming an endless image by rotating. Conductivity is within a range of 0.1 mm or less in straightness and 0.1 mm or less in deflection. A support is preferred. Exceeding the range of straightness and shake makes it difficult to form a good image.

As the conductive material, a metal drum such as aluminum or nickel, a plastic drum deposited with aluminum, tin oxide, indium oxide or the like, or a paper / plastic drum coated with a conductive substance can be used. The conductive support preferably has a specific resistance of 10 ³ Ωcm or less at room temperature. The conductive support of the present invention is most preferably an aluminum support. As the aluminum support, one in which components such as manganese, zinc, magnesium and the like are mixed in addition to the main component aluminum is also used.

Intermediate layer In the present invention, an intermediate layer is preferably provided between the conductive support and the photosensitive layer.

  The intermediate layer used in the present invention preferably contains N-type semiconductor particles. The N-type semiconductive particle means a particle whose main charge carrier is an electron. That is, since the main charge carriers are electrons, the intermediate layer containing the N-type semiconductive particles in the insulating binder effectively blocks hole injection from the substrate, and the electrons from the photosensitive layer. In contrast, it has a property of low blocking.

  Here, a method for discriminating N-type semiconductor particles will be described.

  An intermediate layer having a thickness of 5 μm is formed on the conductive support (the intermediate layer is formed using a dispersion in which 50% by mass of particles are dispersed in the binder resin constituting the intermediate layer). The intermediate layer is negatively charged, and the light attenuation characteristic is evaluated. In addition, the light attenuation characteristics are similarly evaluated by charging to positive polarity.

  N-type semiconductive particles are particles that are dispersed in the intermediate layer in the above evaluation when the light attenuation when charged negatively is greater than the light attenuation when charged positively. It is called semiconductive particle.

As the N-type semiconductor particles, titanium oxide (TiO ₂ ) and zinc oxide (ZnO) are preferable, and titanium oxide is particularly preferably used.

  As the N-type semiconductor particles, fine particles having a number average primary particle diameter in the range of 3.0 to 200 nm are used. Particularly, 5 nm to 100 nm is preferable. The number average primary particle diameter is a measured value as the average diameter in the ferret direction by image analysis by magnifying fine particles 10,000 times by transmission electron microscope observation, randomly observing 100 particles as primary particles. N-type semiconducting particles having a number average primary particle size of less than 3.0 nm are difficult to uniformly disperse in the intermediate layer binder, and easily form aggregated particles. Is likely to occur. On the other hand, N-type semiconducting particles having a number average primary particle size larger than 200 nm tend to make large irregularities on the surface of the intermediate layer, and the reproducibility of dot images tends to deteriorate through these large irregularities. In addition, the N-type semiconductive particles having a number average primary particle size larger than 200 nm are likely to precipitate in the dispersion and easily generate aggregates. As a result, the reproducibility of the dot image tends to deteriorate.

  The titanium oxide particles have anatase, rutile, brookite, and amorphous forms as crystal forms. Among them, the rutile form titanium oxide pigment or the anatase form titanium oxide pigment has a rectifying property of charge passing through the intermediate layer. In other words, the mobility of electrons is increased, the charging potential is stabilized, the residual potential is prevented from increasing, and the dot image is prevented from deteriorating, which is most preferable as the N-type semiconductor particles of the present invention. .

  N-type semiconductive particles are preferably surface-treated with a polymer containing methylhydrogensiloxane units. The molecular weight of the polymer containing the methyl hydrogen siloxane unit is 1000 to 20000, and the surface treatment effect is high. As a result, the rectifying property of the N-type semiconductor particles is improved, and the N-type semiconductor particles are contained. By using the intermediate layer, the occurrence of black spots is prevented and there is an effect on the reproducibility of good dot images.

The polymer containing a methylhydrogensiloxane unit is preferably a copolymer of a structural unit of-(HSi (CH ₃ ) O)-and a structural unit other than this (other siloxane unit). As other siloxane units, dimethylsiloxane units, methylethylsiloxane units, methylphenylsiloxane units, diethylsiloxane units, and the like are preferable, and dimethylsiloxane is particularly preferable. The proportion of methylhydrogensiloxane units in the copolymer is 10 to 99 mol%, preferably 20 to 90 mol%.

  The methylhydrogensiloxane copolymer may be any of a random copolymer, a block copolymer, a graft copolymer, etc., but a random copolymer and a block copolymer are preferred. In addition to methylhydrogensiloxane, the copolymerization component may be one component or two or more components.

  The intermediate layer coating solution prepared for forming the intermediate layer used in the present invention is composed of a binder resin, a dispersion solvent and the like in addition to the N-type semiconductive particles such as the surface-treated titanium oxide.

  The ratio of the N-type semiconductive particles in the intermediate layer is preferably 1.0 to 2.0 times in terms of the volume ratio of the intermediate layer to the binder resin (when the volume of the binder resin is 1). By using the N-type semiconducting particles of the present invention at such a high density in the intermediate layer, the rectification of the intermediate layer is enhanced, and the increase in residual potential and dot image degradation are effective even when the film thickness is increased. Therefore, a good organic photoreceptor can be formed. Further, such an intermediate layer preferably uses 100 to 200 parts by volume of N-type semiconductive particles with respect to 100 parts by volume of the binder resin.

  On the other hand, the binder resin in which these particles are dispersed to form the layer structure of the intermediate layer is preferably a polyamide resin in order to obtain good dispersibility of the particles, but the polyamide resin shown below is particularly preferable.

  That is, a polyamide resin having a heat of fusion of 0 to 40 J / g and a water absorption of 5% by mass or less is preferable for the intermediate layer. The heat of fusion is more preferably 0 to 30 J / g, and most preferably 0 to 20 J / g. On the other hand, when the water absorption exceeds 5% by mass, the moisture content in the intermediate layer increases, the rectification property of the intermediate layer decreases, black spots tend to occur, and the reproducibility of the dot image tends to deteriorate. The water absorption is more preferably 4% by mass or less.

  The heat of fusion of the resin is measured by DSC (Differential Scanning Calorimetry). However, if the same measurement value as the DSC measurement value is obtained, the DSC measurement method is not particular. The heat of fusion is determined from the endothermic peak area when the DSC temperature rises.

  On the other hand, the water absorption rate of the resin is determined by mass change by the water immersion method or by the Karl Fischer method.

  The binder resin for the intermediate layer is preferably an alcohol-soluble polyamide resin. As the binder resin for the intermediate layer of the organic photoreceptor, a resin having excellent solvent solubility is required in order to form the intermediate layer with a uniform film thickness. As such an alcohol-soluble polyamide resin, a copolymerized polyamide resin or a methoxymethylated polyamide resin composed of a chemical structure with few carbon chains between amide bonds such as 6-nylon described above is known. This resin has a high water absorption rate, and the intermediate layer using such a polyamide tends to be highly environment-dependent. As a result, for example, charging characteristics and sensitivity under high temperature and high humidity and low temperature and low humidity are likely to change. Dot image is likely to deteriorate.

  Alcohol-soluble polyamide resin improves the above-mentioned drawbacks and improves the disadvantages of conventional alcohol-soluble polyamide resins by giving the characteristics of heat of fusion 0-40 J / g and water absorption of 5% by mass or less. Even if the external environment changes or even if the organic photoreceptor is used continuously for a long time, a good electrophotographic image can be obtained.

  Hereinafter, the alcohol-soluble polyamide resin having a heat of fusion of 0 to 40 J / g and a water absorption of 5% by mass or less will be described.

  The alcohol-soluble polyamide resin is preferably a polyamide resin containing a repeating unit structure having 7 to 30 carbon atoms between amide bonds in an amount of 40 to 100 mol% of the entire repeating unit structure.

  Here, a repeating unit structure having 7 to 30 carbon atoms between amide bonds will be described. The repeating unit structure means an amide bond unit forming a polyamide resin. This is because a polyamide resin (type A) formed by condensation of a compound having a repeating unit structure having both an amino group and a carboxylic acid group, and a polyamide resin (type B) formed by condensation of a diamino compound and a dicarboxylic acid compound. ) In both examples.

  That is, the repeating unit structure of type A is represented by the general formula (3), and the carbon number contained in X is the carbon number of the amide bond unit in the repeating unit structure. On the other hand, the repeating unit structure of type B is represented by the general formula (4), and the number of carbon atoms contained in Y and the number of carbon atoms contained in Z are the number of carbon atoms of the amide bond unit in the repeating unit structure.

In general formula (3), R ₁ is a hydrogen atom, a substituted or unsubstituted alkyl group, X is a substituted or unsubstituted alkylene group, a group containing a divalent cycloalkane, a divalent aromatic group, and these A mixed structure is shown, and l is a natural number.

In general formula (4), R ₂ and R ₃ are each hydrogen atom, a substituted or unsubstituted alkyl group, Y and Z are each substituted or unsubstituted alkylene group, a group containing a divalent cycloalkane, and a divalent group. And m and n are natural numbers.

  As described above, the repeating unit structure having 7 to 30 carbon atoms includes a substituted or unsubstituted alkylene group, a group containing a divalent cycloalkane, a divalent aromatic group, and a chemical structure having a mixed structure thereof. Among them, a chemical structure having a group containing a divalent cycloalkane is preferable.

  The polyamide resin has 7 to 30 carbon atoms between amide bonds in the repeating unit structure, preferably 9 to 25, more preferably 11 to 20. The proportion of the repeating unit structure having 7 to 30 carbon atoms between amide bonds in the entire repeating unit structure is 40 to 100 mol%, preferably 60 to 100 mol%, more preferably 80 to 100 mol%.

  If the number of carbon atoms is less than 7, the hygroscopicity of the polyamide resin is large, electrophotographic characteristics, particularly the humidity dependence of the potential during repeated use is large, and image defects such as black spots are more likely to occur. Reproducibility tends to deteriorate. If it is larger than 30, the dissolution of the polyamide resin in the coating solvent becomes worse, and it is not suitable for forming a coating film of the intermediate layer.

  Further, when the ratio of the repeating unit structure having 7 to 30 carbon atoms between amide bonds to the entire repeating unit structure is smaller than 40 mol%, the above effect is reduced.

  Preferred polyamide resins of the present invention include polyamides having a repeating unit structure represented by the following general formula (5).

In General Formula (5), Y ₁ represents a group containing a divalent alkyl-substituted cycloalkane, Z ₁ represents a methylene group, m represents 1 to 3, and n represents 3 to 20.

In the general formula (5), the group containing a divalent alkyl-substituted cycloalkane of Y ₁ preferably has the following chemical structure. That is, the polyamide resin of the present invention in which Y ₁ has the following chemical structure has a remarkable effect of preventing black spots and dot image deterioration.

In the above chemical structure, A represents a single bond and an alkylene group having 1 to 4 carbon atoms, R ₄ represents a substituent, represents an alkyl group, and p represents a natural number of 1 to 5. However, the plurality of R ₄ may be the same or different.

  Specific examples of the polyamide resin include the following examples.

  In the above specific examples, “%” in parentheses indicates the ratio (mol%) of the repeating unit structure having 7 or more carbon atoms between amide bonds in the repeating unit structure.

  Among the above specific examples, N-1 to N-4 polyamide resins having a repeating unit structure of the general formula (5) are particularly preferable.

  The molecular weight of the polyamide resin is preferably 5,000 to 80,000, more preferably 10,000 to 60,000 in terms of number average molecular weight. When the number average molecular weight is 5,000 or less, the uniformity of the film thickness of the intermediate layer is deteriorated, and the effects of the present invention are not sufficiently exhibited. On the other hand, if it is larger than 80,000, the solvent solubility of the resin is likely to be reduced, and an agglomerated resin is likely to be generated in the intermediate layer, which tends to cause black spots and deterioration of the dot image.

  A part of the polyamide resin is already available on the market. For example, the polyamide resin is sold under the trade names such as Vestamelt X1010 and X4685 manufactured by Daicel Degussa Co., Ltd., and can be produced by a general synthesis method of polyamide. However, an example of a synthesis example is given below.

Synthesis of exemplified polyamide resin (N-1) 215 parts by mass of lauryl lactam, 3-aminomethyl-3,5,5-trimethylcyclohexylamine in a polymerization kettle equipped with a stirrer, nitrogen, nitrogen introduction tube, thermometer, dehydration tube, etc. 112 parts by mass, 153 parts by mass of 1,12-dodecanedicarboxylic acid and 2 parts by mass of water were mixed and reacted for 9 hours while distilling water under heating and pressure. When the polymer was taken out and the copolymer composition was determined by C ¹³ -NMR, it coincided with the composition of N-1. The melt flow index (MFI) of the synthesized copolymer was 5 g / 10 min under the condition of (230 ° C./2.16 kg).

As the solvent for dissolving the polyamide resin and preparing the coating solution, alcohols having 2 to 4 carbon atoms such as ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol, t-butanol, sec-butanol are preferable, It is excellent in the solubility of polyamide and the coating property of the prepared coating solution. 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 of the present invention is preferably 0.3 to 10 μm. If the thickness of the intermediate layer is less than 0.5 μm, black spot is likely to occur and the dot image is likely to deteriorate. If it exceeds 10 μm, the residual potential is likely to increase, and the reproducibility of the dot image tends to deteriorate. As for the film thickness of an intermediate | middle layer, 0.5-5 micrometers is more preferable.

Moreover, it is preferable that the said intermediate | middle layer is an insulating layer substantially. Here, the insulating layer has a volume resistance of 1 × 10 ⁸ or more. The volume resistance of the intermediate layer and the protective layer of the present invention is preferably 1 × 10 ⁸ to 10 ¹⁵ Ω · cm, more preferably 1 × 10 ⁹ to 10 ¹⁴ Ω · cm, and further preferably 2 × 10 ⁹ to 1 ×. 10 ¹³ Ω · cm. The volume resistance can be measured as follows.

  Measurement conditions: According to JIS: C2318-1975.

Measuring instrument: Hiresta IP manufactured by Mitsubishi Yuka
Measurement conditions: Measurement probe HRS
Applied voltage: 500V
Measurement environment: 30 ± 2 ℃, 80 ± 5RH%
If the volume resistance is less than 1 × 10 ⁸ , the charge blocking property of the intermediate layer decreases, the occurrence of black spots increases, the potential holding property of the organic photoreceptor deteriorates, and good image quality cannot be obtained. On the other hand, if it is greater than 10 ¹⁵ Ω · cm, the residual potential tends to increase in repeated image formation, and good image quality cannot be obtained.

Photosensitive layer The photosensitive layer configuration of the photoreceptor of the present invention may be a single-layer photosensitive layer configuration in which the intermediate layer has a charge generation function and a charge transport function in one layer, but more preferably the function of the photosensitive layer. The charge generation layer (CGL) and the charge transport layer (CTL) may be separated from each other. By adopting a configuration in which the functions are separated, an increase in the residual potential due to repeated use can be controlled small, and other electrophotographic characteristics can be easily controlled according to the purpose. In the negatively charged photoconductor, it is preferable that a charge generation layer (CGL) is formed on the intermediate layer and a charge transport layer (CTL) is formed thereon.

  The structure of the photosensitive layer of the function-separated negatively charged photoreceptor will be described below.

Charge generation layer In the organic photoreceptor of the present invention, the aforementioned titanyl phthalocyanine adduct pigment is used as a charge generation material, but other phthalocyanine pigments, azo pigments, perylene pigments, azurenium pigments and the like can be used in combination. .

  When a binder is used as the CGM dispersion medium in the charge generation layer, a known resin can be used as the binder, but the most preferred resins include formal resin, butyral resin, silicone resin, silicone-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 0.3 μm to 2 μm.

Charge Transport Layer As described above, in the present invention, the charge transport layer is preferably composed of a plurality of charge transport layers, and the uppermost charge transport layer contains the inorganic particles of the present invention.

  The charge transport layer contains a charge transport material (CTM) and a binder resin that disperses and forms a CTM. As other substances, additives such as an antioxidant may be contained in addition to the inorganic particles as necessary.

  As the charge transport material (CTM), a known hole transport property (P-type) charge transport material (CTM) is preferably used. For example, a triphenylamine derivative, a hydrazone compound, a styryl compound, a benzidine compound, a butadiene compound, or the like can be used. These charge transport materials are usually dissolved in a suitable binder resin to form a layer.

  The binder resin used for the charge transport layer (CTL) may be either a thermoplastic resin or a thermosetting resin. For example, polystyrene, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, polyvinyl butyral resin, epoxy resin, polyurethane resin, phenol resin, polyester resin, alkyd resin, polycarbonate resin, silicone resin, melamine resin, and these resins A copolymer resin containing two or more of the repeating unit structures. In addition to these insulating resins, high molecular organic semiconductors such as poly-N-vinylcarbazole can be used. Of these, polycarbonate resins are most preferred because of their low water absorption and good CTM dispersibility and electrophotographic characteristics.

  The ratio of the binder resin to the charge transport material is preferably 50 to 200 parts by mass with respect to 100 parts by mass of the binder resin.

  The total thickness of the charge transport layer is preferably 10 to 40 μm. If the total film thickness is less than 10 μm, image unevenness is likely to occur, and if it exceeds 40 μm, the residual power is likely to increase, and the sharpness tends to deteriorate. Further, the thickness of the charge transport layer serving as the surface layer is preferably 0.5 to 10 μm.

  Solvents or dispersion media used to form layers such as intermediate layers, charge generation layers, and charge transport layers include n-butylamine, diethylamine, ethylenediamine, isopropanolamine, triethanolamine, triethylenediamine, N, N-dimethylformamide, acetone , Methyl ethyl ketone, methyl isopropyl ketone, cyclohexanone, benzene, toluene, xylene, chloroform, dichloromethane, 1,2-dichloroethane, 1,2-dichloropropane, 1,1,2-trichloroethane, 1,1,1-trichloroethane, trichloroethylene, Tetrachloroethane, tetrahydrofuran, dioxolane, dioxane, methanol, ethanol, butanol, isopropanol, ethyl acetate, butyl acetate, dimethyl sulfoxide, methyl cello Lube, and the like. Although this invention is not limited to these, Dichloromethane, 1, 2- dichloroethane, methyl ethyl ketone, etc. are used preferably. These solvents may be used alone or as a mixed solvent of two or more.

  Further, the coating solution for each layer is preferably filtered with a metal filter, a membrane filter or the like in order to remove foreign matters and aggregates in the coating solution before entering the coating step. For example, it is preferable to select a pleat type (HDC), a depth type (profile), a semi-depth type (profile star), etc., manufactured by Nippon Pole Co., Ltd. according to the characteristics of the coating solution and perform filtration.

  Next, as a coating processing method for producing the organic photoreceptor, a coating processing method such as dip coating or spray coating is used in addition to the ride hopper type coating apparatus. For forming the surface layer of the present invention, it is most preferable to use a circular slide hopper type coating apparatus.

  Among the above coating liquid supply type coating apparatuses, the coating method using a slide hopper type coating apparatus is most suitable when the above-described dispersion using a low boiling point solvent is used as the coating liquid, and is a cylindrical photoconductor. In this case, the coating is preferably performed using a circular slide hopper type coating apparatus described in detail in JP-A No. 58-189061 and the like.

  The circular slide hopper type coating apparatus will be briefly described below.

  In the present invention, the coating liquid in which the inorganic particles of the present invention are dispersed is advantageously coated using a circular slide hopper type coating apparatus. As an example of a circular slide hopper type coating device, for example, as shown in a longitudinal sectional view in FIG. 1, the cylindrical base materials 251A and 251B vertically stacked along the center line XX are continuously raised in the direction of the arrow. The coating liquid L is applied by a portion (abbreviated as an application head) 260 that directly surrounds the periphery of the substrate 251 and is directly related to the application of the slide hopper type application device. The base material may be a hollow drum, for example, an aluminum drum, a plastic drum, or a seamless belt type base material. As shown in FIG. 2, a narrow coating liquid distribution slit (abbreviated as a slit) 262 having a coating liquid outlet 261 that opens toward the substrate 251 is formed in the coating head 260 in the horizontal direction. The slit 262 communicates with the annular coating liquid distribution chamber 263, and the coating liquid L in the storage tank 254 is supplied to the annular coating liquid distribution chamber 263 via the supply pipe 264 by the pressure feed pump 255. Yes. On the other hand, on the lower side of the coating liquid outlet 261 of the slit 262, there is formed a slide surface 265 that is continuously inclined and formed to end with a dimension slightly larger than the outer dimension of the substrate. . Furthermore, a lip-like part (bead; liquid reservoir part) 266 extending downward from the end of the slide surface 265 is formed. In application by such an applicator, when the coating liquid L is pushed out from the slit 262 and flows down along the slide surface 265 in the process of pulling up the substrate 251, the photosensitive liquid reaching the end of the slide surface becomes the end of the slide surface. A bead is formed between the outer peripheral surface of the substrate 251 and then applied to the substrate surface. Excess photosensitive solution is discharged from the discharge unit 267.

  The circular slide hopper type coating apparatus causes the coating liquid to flow down along the slide surface 265, and the coating liquid reaching the end of the slide surface 265 is beaded between the end of the slide surface 265 and the cylindrical base 251A. After forming, a coating film is formed on a cylindrical base material.

  In the coating method using a circular slide hopper type coating apparatus, the slide surface end and the base material are arranged with a certain gap (about 2 μm to 2 mm), so that the base material is not damaged, and layers having different properties are multilayered. Even in the case of forming, it can be applied without damaging the already applied layer. In addition, when multiple layers with different properties and dissolved in the same solvent are formed, the time in the solvent is much shorter than in the dip coating method. Since it can apply | coat without eluting, it can apply | coat, without deteriorating the dispersibility of the inorganic particle of this invention.

  Next, an image forming method and an image forming apparatus using the organic photoreceptor of the present invention will be described.

  FIG. 3 is a cross-sectional configuration diagram of an image forming apparatus as an example of the image forming method of the present invention.

  In FIG. 3, reference numeral 50 denotes a photosensitive drum (photosensitive member) which is an image bearing member, and is a photosensitive member coated with an organic photosensitive layer on the drum, which is grounded and rotated clockwise. Reference numeral 52 denotes a scorotron charger (charging means) for uniformly charging the circumferential surface of the photosensitive drum 50 by corona discharge. Prior to the charging by the charger 52, the peripheral surface of the photosensitive member may be discharged by performing exposure by the pre-charging exposure unit 51 using a light emitting diode or the like in order to eliminate the history of the photosensitive member in the previous image formation.

  After uniform charging of the photoreceptor, image exposure based on the image signal is performed by an image exposure unit 53 as an image exposure unit. The image exposure unit 53 in this figure uses a laser diode (not shown) as an exposure light source. Scanning on the photosensitive drum is performed by the light whose optical path is bent by the reflection mirror 532 through the rotating polygon mirror 531 and the fθ lens, and an electrostatic latent image is formed.

  Here, the reversal development process means that the surface of the photoreceptor is uniformly charged by the charger 52, and the exposed area of the photoreceptor, that is, the exposed area potential (exposed area) of the photoreceptor is developed by the developing process (means). This is an image forming method for visualizing. On the other hand, the unexposed portion potential is not developed by the developing bias potential applied to the developing sleeve 541.

The electrostatic latent image is then developed by a developing device 54 as developing means. A developing device 54 containing a developer composed of toner and carrier is provided on the periphery of the photosensitive drum 50, and development is performed by a developing sleeve 541 that contains a magnet and rotates while holding the developer. The inside of the developing device 54 is composed of developer agitating / conveying members 544 and 543, a conveying amount regulating member 542, and the like, and the developer is agitated and conveyed and supplied to the developing sleeve. Controlled by member 542. The developer transport amount varies depending on the linear velocity and developer specific gravity of the applied electrophotographic photosensitive member, but is generally in the range of ^{20 to} 200 mg / cm ² .

  The developer is, for example, a carrier composed of the above-mentioned ferrite as a core and coated with an insulating resin around it, a coloring agent such as carbon black, a charge control agent, and a low-molecular-weight polyolefin mainly composed of the above-mentioned styrene acrylic resin. The toner is composed of toner in which silica, titanium oxide or the like is externally added to the particles, and the developer is transported to the development area with the layer thickness regulated by the transport amount regulating member, and development is performed. At this time, usually, development is performed by applying a DC bias between the photosensitive drum 50 and the developing sleeve 541 and, if necessary, an AC bias voltage. Further, the developer is developed in contact with or not in contact with the photoreceptor. The potential of the photoconductor is measured by providing a potential sensor 547 above the development position as shown in FIG.

  The recording paper P is fed to the transfer area by the rotation operation of the paper feed roller 57 when the transfer timing is ready after the image formation.

  In the transfer area, a transfer electrode (transfer means: transfer device) 58 is operated on the peripheral surface of the photosensitive drum 50 in synchronization with the transfer timing, and the charged recording paper P is charged with a polarity opposite to that of the toner. Transfer the toner.

  Next, the recording paper P is neutralized by a separation electrode (separator) 59, separated by the peripheral surface of the photosensitive drum 50 and conveyed to the fixing device 60, and the toner is removed by heating and pressurization of the heat roller 601 and the pressure roller 602. After the welding, the sheet is discharged to the outside of the apparatus via the sheet discharge roller 61. The transfer electrode 58 and the separation electrode 59 stop the primary operation after passing through the recording paper P, and prepare for the next toner image formation. In FIG. 3, a transfer band electrode of corotron is used as the transfer electrode 58. The transfer electrode setting conditions vary depending on the process speed (peripheral speed) of the photosensitive member and cannot be specified. For example, the transfer current is set to +100 to +400 μA, and the transfer voltage is set to +500 to +2000 V. can do.

  On the other hand, after the recording paper P is separated, the photosensitive drum 50 removes and cleans residual toner by pressure contact of the blade 621 of the cleaning device (cleaning means) 62, and again performs charge removal by the pre-charge exposure unit 51 and charging by the charger 52. Then, the next image forming process is started.

  Reference numeral 70 denotes a detachable process cartridge in which a photoconductor, a charger, a transfer device, a separator, and a cleaning device are integrated.

  The electrophotographic photosensitive member of the present invention is generally applicable to electrophotographic apparatuses such as an electrophotographic copying machine, a laser printer, an LED printer, and a liquid crystal shutter printer, and further displays, recordings, light printing, plate making and the like using electrophotographic technology. It can be widely applied to apparatuses such as facsimiles.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, the aspect of this invention is not limited to this. In the following text, “part” means “part by mass”.

Production of Photoreceptor 1 Photoreceptor 1 was produced as follows.

Intermediate layer 1
On the washed cylindrical aluminum substrate (10-point surface roughness Rz: 0.45 μm processed by cutting), the following intermediate layer coating solution was applied by dip coating, dried at 120 ° C. for 30 minutes, and dried film An intermediate layer 1 having a thickness of 5 μm was formed.

  The following intermediate layer dispersion is diluted twice with the same mixed solvent, and is allowed to stand overnight and then filtered (filter; rigesh mesh filter made by Nippon Pole Co., Ltd., nominal filtration accuracy: 5 microns, pressure: 50 kPa). Produced.

(Preparation of intermediate layer dispersion)
Binder resin: (Exemplary polyamide N-1) 1 part Rutile-type titanium oxide (primary particle size 35 nm; titanium oxide pigment prepared by surface treatment with dimethylpolysiloxane having a hydroxyl group at the terminal and having a hydrophobicity of 33) 6 parts ethanol / n-propyl alcohol / THF (= 45/20/30 mass ratio) 10 parts The above components are mixed and dispersed in a batch system for 10 hours using a sand mill disperser. Produced.

<Charge generation layer: CGL>
Charge generation material (CGM): oxytitanyl phthalocyanine (a titanyl phthalosine pigment having a maximum diffraction peak at a Bragg angle (2θ ± 0.2 °) of 27.3 ° in an X-ray diffraction spectrum by Cu-Kα characteristic X-ray) 24 parts polyvinyl butyral resin “S-REC BL-1” (manufactured by Sekisui Chemical Co., Ltd.) 12 parts 2-butanone / cyclohexanone = 4/1 (v / v) 300 parts The above composition is mixed, dispersed using a sand mill, and charged. A generation layer coating solution was prepared. This coating solution was applied by a dip coating method to form a charge generation layer having a dry film thickness of 0.5 μm on the intermediate layer.

<Charge transport layer 1 (CTL1)>
Charge transport material (4,4′-dimethyl-4 ″-(α-phenylstyryl)
Triphenylamine) 225 parts Polycarbonate (Z300: Mitsubishi Gas Chemical Co., Ltd.) 300 parts Antioxidant (Irganox 1010: Nihon Ciba Geigy) 6 parts Dichloromethane 2000 parts Silicon oil (KF-54: Shin-Etsu Chemical Co., Ltd.) 1 part mixed And dissolved to prepare a charge transport layer coating solution 1. This coating solution was applied onto the charge generation layer by a dip coating method and dried at 110 ° C. for 70 minutes to form a charge transport layer 1 having a dry film thickness of 18.0 μm.

<Charge transport layer 2 (CTL2)>
Inorganic particles: Silica particles (Silica treated with hexamethyldisilazane and having an average primary particle size of 35 nm: Hydrophobic degree 72, Hydrophobic degree distribution value 20) 60 parts Charge transport material (4,4'-dimethyl-4 " -(Α-phenylstyryl)
Triphenylamine) 150 parts Polycarbonate (Z300: Mitsubishi Gas Chemical Co., Ltd.) 300 parts Antioxidant (Irganox 1010: Nihon Ciba Geigy) 12 parts THF: Tetrahydrofuran 2800 parts Silicon oil (KF-54: Shin-Etsu Chemical Co., Ltd.) 4 parts Were mixed, dispersed and dissolved to prepare a charge transport layer coating solution 2. This coating solution is applied onto the charge transport layer 1 with a circular slide hopper coater, dried at 110 ° C. for 70 minutes to form a charge transport layer 2 having a dry film thickness of 2.0 μm, and the photoreceptor 1 is formed. Produced.

Production of Photoreceptors 2-13 Photoreceptor 1 except that Rz of the conductive support, the intermediate layer, and the type of inorganic particles of the charge transport layer 2 (CTL2) were changed as shown in Table 1 in the production of Photoreceptor 1. Photoconductors 2 to 13 were produced in the same manner as described above.

Production of Photoreceptor 14 In the production of Photoreceptor 1, the same procedure as for Photoreceptor 1 except that Rz of the conductive support was changed to 0.11 μm and the amount of inorganic particles in the charge transport layer 2 (CTL2) was changed to 6 parts. Thus, a photoreceptor 14 was produced.

  In Table 1, inorganic particles 1 represent silica, inorganic particles 2 represent alumina, and inorganic particles 3 represent titanium oxide. Moreover, about the surface treatments 1 and 2 of an inorganic particle, the surface treatment using the following surface treating agent is shown.

Surface treatment 1; Hexamethyldisilazane Surface treatment 2; Trimethylsilanol The hydrophobicity and hydrophobicity distribution values of the inorganic particles used in the photoreceptors 1 to 12 are the conditions for the surface treatment together with the surface treatment agent for the inorganic particles. (Adjusted by changing conditions such as water vapor partial pressure, surface treatment partial pressure, total pressure, reaction temperature)
The contents of the intermediate layer in Table 1 are listed in Table 2.

  The volume ratio of the intermediate layer in Table 2 is the same as the total volume of the binder resin and the N-type semiconductive particles in all the intermediate layers of the photoreceptors 1 to 13, and The intermediate layer dispersion is prepared by changing the volume ratio (Vn / Vb) of the conductive particles to form the intermediate layer.

In Table 2,
A1 is rutile titanium oxide A2 is anatase titanium oxide * 1 is a copolymer of methylhydrogensiloxane and dimethylsiloxane (molar ratio 1: 1)
* 2 is a copolymer of methylhydrogensiloxane and dimethylsiloxane (molar ratio 9: 1)
* 3 is a copolymer of methylhydrogensiloxane and dimethylsiloxane (molar ratio 2: 8)
* 4 is a copolymer of methylhydrogensiloxane and diethylsiloxane (molar ratio 1: 1)
* 5: Copolymer of methylhydrogensiloxane and methylethylsiloxane (molar ratio 1: 1)
* 6 Methyl hydrogen polysiloxane In Table 2, the surface treatment refers to the substance used for the surface treatment applied to the surface of the particles.

  The heat of fusion and water absorption in the table were measured as follows.

Measurement conditions of heat of fusion Measuring machine: Measured using Shimadzu Corporation “Shimadzu heat flow rate differential scanning calorimeter DSC-50”.

  Measurement conditions: The measurement sample is set in the above-mentioned measuring machine, measurement is started from room temperature (24 ° C.), the temperature is raised to 200 ° C. at 5 ° C./min, and then cooled to room temperature at 5 ° C./min. This is repeated twice, and the heat of fusion is calculated from the endothermic peak area due to melting during the second temperature increase.

Measurement condition of water absorption rate The sample to be measured is sufficiently dried at 70 to 80 ° C. for 3 to 4 hours, and its mass is accurately weighed. Next, the sample is put into ion-exchanged water maintained at 20 ° C., and after a certain period of time, the sample surface is pulled up and wiped off with a clean cloth, and the mass is measured. The above operation was repeated until the increase in mass was saturated, and the value obtained by dividing the increased mass (increase) of the resulting sample by the initial mass was taken as the water absorption rate.

  In Table 2, the ratio of the unit structure having 7 or more carbon atoms refers to the ratio (mol%) of the repeating unit structure having 7 or more carbon atoms between amide bonds in the repeating unit structure.

Evaluation Each of the photoreceptors 1 to 14 obtained as described above is a reversal development type digital copying machine "Konica 7085" manufactured by Konica Corporation (a scorotron charger, a semiconductor laser image exposure device (wavelength 680 nm), a reversal developing means) The following evaluation items were evaluated. Evaluation is basically performed by copying an original image in which the character ratio, halftone image, solid white image, and solid black image with a pixel rate of 7% are divided into ¼ equal parts in A4 in intermittent mode. did. The evaluation results are shown in Table 3.

Evaluation condition Line speed: 420 mm / second Time to reach from the image exposure to the development position; 0.108 seconds Charging condition Charger; Scorotron charger (negative charge)
Charging potential: -700V to -750V
Exposure condition Set to the exposure amount that makes the solid black image portion potential -100V.

Exposure beam; Laser uses a semiconductor laser of 680 nm, exposure spot area: 7.5 × 10 ⁻¹⁰ m ² , 800 dpi
Development conditions The developer is a volume average particle diameter produced by a polymerization method comprising a carrier coated with an insulating resin with a ferrite core and a styrene acrylic resin as a main material, a carbon black colorant, a charge control agent, and a low molecular weight polyolefin. A toner developer in which silica and titanium oxide were externally added to 5.3 μm colored particles was used.

Transfer conditions Transfer pole; corona charging method (positive charging)
Separation conditions Cleaning conditions using the separation means of the separation claw unit A cleaning blade having a hardness of 70 °, a rebound resilience of 65%, a thickness of 2 (mm), and a free length of 9 mm is applied to the cleaning portion at a linear pressure of 18 (g / cm) It contact | abutted by the weight load system so that it might become.

Image density (Evaluated under environmental conditions of 20 ° C and 50%)
Measured using Macbeth RD-918. The relative reflection density was measured with the paper reflection density set to “0”. As the residual potential increases on multiple copies, the image density decreases. The measurement was performed on a solid black image portion after 200,000 copies.

A: Black solid image is higher than 1.2 (good)
○: Black solid image is 1.0 or more and 1.2 or less (no problem in practical use)
×: Black solid image is less than 1.0 (practical problem)
Fogging
The fog density was measured by reflection density of a solid white image using RD-918 manufactured by Macbeth. The reflection density was evaluated by a relative density (the density of A4 paper not printed is 0.000). The measurement was performed on a solid white image portion after 200,000 copies.

A: Concentration is less than 0.010 (good)
○: Concentration of 0.010 or more and 0.020 or less (a level causing no practical problem)
X: Concentration is higher than 0.020 (a level that causes practical problems)
Image blur (evaluated under environmental conditions of 10 ° C and 20%)
◎ No blurring of image through printing 10,000 sheets (good)
○: Several images (less than 10) were generated through printing 10,000 sheets, but there was no practical problem (no problem in practical use)
×: 10 or more partial or total image blurs or 1 or more wide range image blurs occurred during printing on 10,000 sheets (practically problematic)
Reproducibility of dot images (evaluated under environmental conditions of 30 ° C and 80%)
The dot images constituting the image were evaluated by looking through a 100 × magnifier. Evaluation was made with an image after 10,000 prints.

A: The dot image is produced with an increase / decrease of less than 30% compared to the exposure spot area and is reproduced independently, and the halftone gradation is sufficiently reproduced (good).
○: The dot image is produced with an increase / decrease of 30 to 60% compared to the exposure spot area, and each is reproduced independently, and the halftone gradation is also practical (level of practicality).
X: The dot image is produced with an increase / decrease exceeding 60% compared to the exposure spot area, and the dot image disappears or is connected partially or entirely, and the halftone gradation Is insufficient (practical problem level)
Sharpness (evaluated under environmental conditions of 30 ° C and 80%)
The sharpness of the image was evaluated by crushing characters. Character images having different character sizes (points) were formed and evaluated with images after 10,000 prints.

A: Characters of 4 points or less are clear and easy to read (good)
○: Characters of 6 points or less are clear and easy to read (no problem in practical use)
Δ: Characters of 8 points or less are clear and can be easily read (re-evaluation is required)
×: Some or all of the 8-point characters are illegible (practically problematic)
Amount of film thickness depletion The film thickness of the photosensitive layer is measured at 10 points at random in the uniform film thickness portion, and the average value is taken as the film thickness of the photosensitive layer. The film thickness measuring device is an eddy current type film thickness measuring device EDDY560C (manufactured by HELMUT FISCHER GMBTE CO), and the difference in the photosensitive layer thickness before and after the 200,000 print printing test is used as the film thickness depletion amount. .

  From the results of Table 3, it has a surface layer (= charge transport layer 2) containing inorganic particles having a number average primary particle size of 3 to 150 nm, and a surface roughness Ra of 0.001 to 0.018. Organic photoreceptors (No. 1 to 3 and 8 to 13) having a point surface roughness Rz of 0.02 to 0.08 μm have good image blur and dot image reproducibility, and image density. In addition, the fog has also been evaluated beyond the range of practicality, and the electrophotographic image having a good sharpness has been obtained with less film thickness loss. On the other hand, in the photoreceptor 4 in which the surface layer contains silica having a number average primary particle size of 1 nm, the dispersibility of the silica is deteriorated, and Ra is also large because the aggregate of silica is dispersed in the surface layer. The image density is lowered, the image is blurred, the dot image is deteriorated, and the sharpness is inferior. Further, the Rz of the conductive support is large, and therefore, the surface layer Rz has a tendency that the active gas easily adheres to the uneven portions on the surface of the photoconductor 5 of the present invention, and the reproducibility of image blur and dot image deteriorates. Yes. In addition, the photoreceptor 6 containing silica with a number average primary particle size of 160 nm in the surface layer has a large surface layer Ra, and active gas tends to adhere to it, causing image blurring, and the reproducibility of the dot image is deteriorated. The sharpness has deteriorated. Further, the photoreceptor 14 having a small Ra and Rz on the surface layer has a large film thickness wear amount, and the image density is lowered and the image quality is deteriorated.

It is sectional drawing of the example of the circular slide hopper type coating device concerning this invention. It is a perspective view of the example of a circular slide hopper type application device concerning the present invention. 1 is a cross-sectional configuration diagram of an image forming apparatus as an example of an image forming method of the present invention. It is a figure of a hydrophobization degree distribution curve.

Explanation of symbols

50 Photosensitive drum (photosensitive member)
DESCRIPTION OF SYMBOLS 51 Pre-charge exposure part 52 Charging device 53 Image exposure device 54 Development device 541 Development sleeve 543, 544 Developer stirring conveyance member 547 Potential sensor 57 Paper feed roller 58 Transfer electrode 59 Separation electrode (separator)
60 Fixing device 61 Paper discharge roller 62 Cleaning device 70 Process cartridge

Claims (18)

In an organic photoreceptor having at least an intermediate layer and a photosensitive layer on a conductive support, the ten-point surface roughness Rz of the conductive support is 0.1 to 1.0 μm, and the number average primary particle size is 3 to 3. having a surface layer containing inorganic particles 150 nm, the surface roughness Ra of 0.001～0.018Myuemu, and ten-point surface roughness Rz Ri 0.02~0.08μm der, of the intermediate layer organic photoreceptor having a thickness and wherein 1~10μm der Rukoto. In an image forming apparatus having an image exposure means for forming an electrostatic latent image on an organic photoreceptor having at least an intermediate layer and a photosensitive layer on a conductive support using an exposure beam having an exposure spot area of 2000 μm ² or less. The conductive support has a 10-point surface roughness Rz of 0.1 to 1.0 μm, a surface layer containing inorganic particles having a number average primary particle size of 3 to 150 nm, and a surface roughness Ra of 0. in .001～0.018Myuemu, and ten-point surface roughness Rz Ri 0.02~0.08μm der, an image forming apparatus thickness of the intermediate layer is characterized 1~10μm der Rukoto. The organophotoreceptor according to claim 1, wherein the inorganic particles are a metal oxide. 2. The organophotoreceptor according to claim 1, wherein the inorganic particles are silica particles. The organophotoreceptor according to claim 1, wherein the inorganic particles have a hydrophobicity of 50 or more and a hydrophobicity distribution value of 25 or less. The organophotoreceptor according to claim 1, wherein the surface layer contains an antioxidant. The organic photoreceptor according to claim 1, wherein the surface layer contains a polycarbonate resin. The organic photoreceptor according to claim 1 , wherein the intermediate layer contains N-type semiconductor particles . The organophotoreceptor according to claim 8, wherein the N-type semiconductor particles are a metal oxide. The organophotoreceptor according to claim 8 or 9, wherein the N-type semiconductor particles are titanium oxide or zinc oxide. The organophotoreceptor according to claim 10, wherein the N-type semiconductor particles are titanium oxide. The organophotoreceptor according to claim 11, wherein the titanium oxide is a rutile titanium oxide pigment or an anatase titanium oxide pigment. The organophotoreceptor according to claim 8, wherein the N-type semiconductor particles are subjected to a surface treatment. The organic photoreceptor according to claim 8, wherein the intermediate layer contains a binder of polyamide resin. The organophotoreceptor according to claim 14, wherein the polyamide resin is a polyamide resin having a heat of fusion of 0 to 40 J / g and a water absorption of 5% by mass or less. 16. The organic photoreceptor according to claim 14, wherein the volume ratio of the binder resin and the N-type semiconductor particles in the intermediate layer is N-type semiconductor particles 1 to 2 with respect to the binder resin 1. An organic photoreceptor, charging means for charging the organic photoreceptor, latent image forming means for forming an electrostatic latent image on the charged organic photoreceptor, developing means for developing the electrostatic latent image into a toner image, Transfer means for transferring the visualized toner image onto the transfer material from the organic photoreceptor, charge eliminating means for removing the charge on the organic photoreceptor after transfer, and residual toner on the organic photoreceptor after transfer are removed. A process cartridge for use in an image forming apparatus having a cleaning unit, wherein the organic photoreceptor and the charging unit, the latent image forming unit, the developing unit, the transfer unit, the discharging unit, A process cartridge which is integrally supported with at least one of cleaning means and can be detachably attached to an image forming apparatus main body. An organic photoreceptor, charging means for charging the organic photoreceptor, latent image forming means for forming an electrostatic latent image on the charged organic photoreceptor, developing means for developing the electrostatic latent image into a toner image, Transfer means for transferring the visualized toner image onto the transfer material from the organic photoreceptor, charge eliminating means for removing the charge on the organic photoreceptor after transfer, and residual toner on the organic photoreceptor after transfer are removed. An image forming apparatus having a cleaning unit, wherein the organic photoreceptor according to any one of claims 1 and 3 to 16 is used.

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