JP2005338543A - Organic photoreceptor, process cartridge and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic photoreceptor capable of solving the conflicting problems of sticking foreign matters and wear resistance, and eliminating uneven images and blurred images due to dash marks and surface scratches, preventing transferred memory, and maintaining excellent potentials and forming sharp electrophotographic images; and also to provide a process cartridge and an image forming device using this organic photoreceptor. <P>SOLUTION: The organic photoreceptor has a photosensitive layer on a conductive support, and the surface layer of the organic photoreceptor contains a charge carrier substance expressed in general formula (1) and fluorinated carbon resin particles 90% crystallized and having an average primary diameter of 0.02 μm or larger but smaller than 0.20 μm. Its contact angle to water is 90° or larger with angle errors of ±2.0°. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an organic photoreceptor (hereinafter also simply referred to as a photoreceptor) used for electrophotographic image formation, a process cartridge, an image forming apparatus, and an image forming method. More specifically, the present invention is used in the fields of copiers and printers. The present invention relates to an organic photoreceptor, a process cartridge, and an image forming apparatus used for electrophotographic image formation.

  In recent years, organic photoreceptors (hereinafter also simply referred to as photoreceptors) have been widely used as electrophotographic photoreceptors. Organic photoreceptors have advantages over other photoreceptors, such as easy development of materials suitable for various exposure light sources from visible light to infrared light, the ability to select materials that are free from environmental pollution, and low manufacturing costs. However, there are disadvantages such as low mechanical strength and easy adhesion of foreign matter, poor chemical durability, deterioration of electrostatic characteristics of a photoreceptor when many sheets are printed, and generation of scratches on the surface.

  That is, the organic photoconductor is a surface generated by a mechanical external force applied when a toner image formed on the photoconductor is transferred to a transfer material such as paper or when residual toner on the photoconductor is cleaned. Durability (abrasion resistance) against foreign matter adhesion and scratches is required.

  Therefore, conventionally, in order to improve the adhesion of foreign matter and abrasion resistance of the photoreceptor, a technique is known in which fluorine-containing resin fine particles such as polytetrafluoroethylene resin (PTFE) are contained in the outermost surface layer of the photoreceptor. In particular, as means for effectively reducing the friction coefficient of the photoreceptor surface and improving the wear resistance, the crystallinity is small (half-value width of the peak of the X-ray diffraction pattern is 0.28 or more), and the particle size is small. A technique using fluorine-containing resin fine particles has been reported (for example, Patent Document 1).

  However, when the crystallinity is lowered, the spreadability of the fluororesin fine particles is increased, the dispersion stability of the fluororesin fine particles in the coating dispersion is lowered, and the particles are aggregated to form a film having uniform characteristics. It is difficult to do so, and dash marks (small comet-like streak images) are generated in an electrophotographic image, and scratches are easily generated on the surface layer, and image unevenness and image blur are likely to occur. Further, when the aggregation of the fluorine-containing resin particles in the surface layer increases, the aggregation interface between the particles easily becomes a charge trap, a memory image such as a transfer memory is easily generated, and the residual potential increases with repeated use. The problem of reducing the concentration is likely to occur.

  In particular, the fluorine-containing resin fine particles having an average particle size of less than 0.20 μm and low crystallinity are remarkably lowered in the stability of the coating dispersion of the fluorine-containing resin fine particles. When the film is formed, it is difficult to form a surface layer having a uniform surface energy due to the generation of aggregates in the dispersion liquid. Such dash marks, image unevenness, image blurring, etc., transfer memory Problems such as generation of memory images such as increase of residual potential due to repeated use have occurred. Among them, the problem of the transfer memory tends to be easily amplified when a highly sensitive phthalocyanine pigment or the like is used as a charge generation material.

Further, as a means for effectively reducing the coefficient of friction on the surface of the photoreceptor, a technique using fluororesin fine particles having a small particle diameter is known. Use of fine particles having a small particle diameter is effective because the surface area becomes large even with the same number of added parts. However, as described above, the low crystalline fluorine-containing resin fine particles have a smaller dispersion uniformity as the diameter is reduced, and it becomes difficult to form a uniform and smooth film free of aggregates, and the image quality is improved from the beginning of printing. Remarkably reduced.
JP-A-8-328287

  The present invention simultaneously solves the conflicting properties of the organophotoreceptor with respect to foreign matter adhesion and wear resistance, prevents image unevenness and image blur due to the occurrence of scratches on the dash mark and surface layer, and The present invention provides an organic photoreceptor capable of preventing an occurrence of a transfer memory and providing an electrophotographic image having good potential characteristics and sharpness in the long term, and a process cartridge and an image forming apparatus using the organic photoreceptor Is to provide.

In order to solve the above problems, the present inventors have studied the surface layer of the organic photoconductor to prevent the generation of the dash mark, image unevenness, and image blur as well as the development of technology capable of preventing the generation of the transfer memory. As a result, the charge transport layer forming the surface layer of the organophotoreceptor coexists with small particle size fluorine-containing resin fine particles having a low crystallinity and a charge transport material having a specific chemical structure, thereby varying the contact angle. The present invention has been completed by finding out that it can be achieved by making it smaller. Further, the organic photoreceptor of the present invention has been found that the effect of the present invention can be exhibited more by providing an intermediate layer containing N-type semiconductive inorganic particles between the conductive support and the photosensitive layer. completed. That is, the object of the present invention can be achieved by having the following configuration.
(Claim 1)
In an organic photoreceptor having a photosensitive layer on a conductive support, the surface layer of the organic photoreceptor has a charge transport material represented by the following general formula (1), an average primary particle size of 0.02 μm or more, and 0.0. Organic containing fluorine-containing resin fine particles having a crystallinity of less than 90% less than 20 μm, a contact angle with water of 90 ° or more, and a variation in contact angle of ± 2.0 ° Photoconductor.

(In General Formula (1), Ar ₁ and Ar ₂ represent a substituted or unsubstituted aromatic ring group, R ₁ and R ₂ represent a hydrogen atom or an alkyl group, and R ₃ represents a hydrogen atom, an alkyl group, or a halogen atom. Represents an atom.)
(Claim 2)
In an organic photoreceptor having a photosensitive layer on a conductive support, the surface layer of the organic photoreceptor has a charge transport material represented by the following general formula (2), an average primary particle size of 0.02 μm or more, and 0.0. Organic containing fluorine-containing resin fine particles having a crystallinity of less than 90% less than 20 μm, a contact angle with water of 90 ° or more, and a variation in contact angle of ± 2.0 ° Photoconductor.

(In General Formula (2), Ar ₁ and Ar ₂ represent a substituted or unsubstituted aromatic ring group, R ₄ represents a hydrogen atom, an alkyl group, or a halogen atom, and X represents a vinylene group or an ethylene group. )
(Claim 3)
The organic photoreceptor according to claim 1, wherein the surface layer contains a binder resin, and at least one of the binder resins is a siloxane-modified polycarbonate.
(Claim 4)
The organophotoreceptor according to claim 1, wherein the fluororesin fine particles coexist with an antioxidant.
(Claim 5)
The surface layer is an organic material having a boiling point of 120 ° C. or less under atmospheric pressure with a fluorine-containing resin fine particle and binder resin having at least an average primary particle size of 0.02 μm or more and less than 0.20 μm and a crystallinity of less than 90%. The organic photoreceptor according to any one of claims 1 to 4, wherein a coating liquid obtained by dispersing and dissolving in a solvent is applied by a coating liquid supply type coating apparatus.
(Claim 6)
The organophotoreceptor according to claim 1, wherein the surface layer contains an antioxidant.
(Claim 7)
The organophotoreceptor according to claim 1, wherein the photosensitive layer has a structure in which a plurality of charge transport layers are stacked on a charge generation layer.
(Claim 8)
The organophotoreceptor according to claim 7, wherein the charge generation layer contains a gallium phthalocyanine pigment.
(Claim 9)
9. The organophotoreceptor according to claim 7, further comprising an intermediate layer containing N-type semiconductive particles between the conductive support and the charge generation layer.
(Claim 10)
The organophotoreceptor according to claim 9, wherein the N-type semiconductor particles are a metal oxide.
(Claim 11)
The organophotoreceptor according to claim 9 or 10, wherein the N-type semiconductor particles are titanium oxide or zinc oxide.
(Claim 12)
The organophotoreceptor according to claim 11, wherein the N-type semiconductor particles are titanium oxide.
(Claim 13)
The organophotoreceptor according to claim 12, wherein the titanium oxide is a rutile titanium oxide pigment or an anatase titanium oxide pigment.
(Claim 14)
The organophotoreceptor according to claim 9, wherein the N-type semiconductor particles are subjected to a surface treatment.
(Claim 15)
The organic photoreceptor according to any one of claims 9 to 14, wherein the intermediate layer contains a polyamide resin binder.
(Claim 16)
16. The organic photoreceptor according to claim 15, 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 17)
The organic photoreceptor according to claim 15 or 16, wherein a 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 18)
The organic photoreceptor according to claim 9, wherein the intermediate layer has a thickness of 1 to 10 μm.
(Claim 19)
An organic photoreceptor and charging means for charging by bringing a charging member into contact with the organic photoreceptor, a developing means for visualizing an electrostatic latent image on the organic photoreceptor, and visualized on the organic photoreceptor Image forming apparatus comprising: transfer means for transferring a toner image onto a transfer material; charge eliminating means for removing charges on the organic photoreceptor after transfer; and cleaning means for removing residual toner on the organic photoreceptor after transfer A process cartridge for use in the present invention, wherein the organic photosensitive member according to any one of claims 1 to 18 and a charging unit, a latent image forming unit, a developing unit, a transferring unit, a discharging unit, and a cleaning unit on the organic photosensitive unit A process cartridge characterized in that at least one means is integrally supported and can be detachably attached to an image forming apparatus main body.
(Claim 20)
An organic photoreceptor and charging means for charging by bringing a charging member into contact with the organic photoreceptor, a developing means for visualizing an electrostatic latent image on the organic photoreceptor, and visualized on the organic photoreceptor Image forming apparatus comprising: transfer means for transferring a toner image onto a transfer material; charge eliminating means for removing charges on the organic photoreceptor after transfer; and cleaning means for removing residual toner on the organic photoreceptor after transfer An image forming apparatus using the organic photoreceptor according to any one of claims 1 to 18.

  By using the present invention, it is possible to provide an organic photoreceptor capable of simultaneously improving the generation of a dash mark, image unevenness and image blur, and the generation of a transfer memory, and capable of producing a good electrophotographic image. A process cartridge and an image forming apparatus using the body can be provided.

  Hereinafter, the present invention will be described in detail.

  The organic photoreceptor of the present invention has a photosensitive layer on a conductive support, the surface layer of the organic photoreceptor has a charge transport material represented by the general formula (1), and an average primary particle size of 0.1. It contains fluorine-containing resin fine particles having a crystallinity of less than 90% and not less than 02 μm and less than 0.20 μm, a contact angle with water of 90 ° or more, and a variation in contact angle of ± 2.0 °. It is characterized by.

  The organic photoreceptor of the present invention is an organic photoreceptor having a photosensitive layer on a conductive support, wherein the surface layer of the organic photoreceptor is a charge transport material represented by the general formula (2) and an average primary It contains fluorine-containing resin fine particles having a particle size of 0.02 μm or more and less than 0.20 μm and a crystallinity of less than 90%, a contact angle with water of 90 ° or more, and a contact angle variation of ± 2. It is 0 degree.

  The organophotoreceptor of the present invention has the above-described configuration, thereby preventing the occurrence of dash marks, image unevenness and image blur, preventing the generation of transfer memory, stabilizing the potential characteristics over the long term, and providing sharpness. A good electrophotographic image can be provided.

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

  That is, the fluororesin fine particles have poor dispersion uniformity as described above, and it has been difficult to form a uniform and smooth film without aggregates. That is, the fluororesin fine particles having a crystallinity of less than 90% and high spreadability are difficult to maintain uniform dispersed particles in the dispersion, and the dispersed particles are aggregated, and the contact layer has a uniform contact angle. It was difficult to form. Improved dispersibility of the fluororesin fine particles having such a low crystallinity and an average primary particle size of 0.02 μm or more and less than 0.20 μm, a contact angle with water of 90 ° or more, and a variation in contact angle By providing a surface layer of ± 2.0 °, an organic photoreceptor capable of preventing the generation of dash marks, black streaks, and white streaks and forming high-quality electrophotographic images over a long period of time is provided. can do.

  The surface layer having the characteristics of the present invention comprises fluorine-containing resin fine particles having an average primary particle size of 0.02 μm or more and less than 0.20 μm and a crystallinity of less than 90% and the general formula (1) or the general formula (2 ) In a low-boiling solvent, preferably using an organic solvent having a boiling point of 120 ° C. or lower under atmospheric pressure (eg, THF, ethanol, toluene, dichloroethane, etc.), A stable dispersion can be produced while suppressing the cohesiveness between the resin fine particles. At the same time, the dispersion liquid is used as a coating liquid to form a surface layer using a coating liquid supply type coating apparatus, and drying is performed to prevent aggregation of the fluororesin fine particles in the surface layer. A surface layer having a reduced thickness is formed.

  The coating liquid supply type coating apparatus means a coating apparatus that supplies and coats a coating liquid necessary for layer formation on a conductive support, and includes, for example, a slide hopper type coating apparatus, an extrusion type coating apparatus, and a spray. A coating apparatus etc. are mentioned. Such a coating liquid supply type coating apparatus forms a surface layer in one way without causing the dispersion to stay in the coating apparatus, as compared with immersion coating in which a conductive support is immersed in the coating liquid. Therefore, the dispersed particles of the fluorine-containing resin fine particles can form a uniform surface layer with less aggregation of the fluorine-containing resin fine particles without repeatedly receiving the aggregation share in the dispersion. Moreover, since a dispersion can be prepared for each photoconductor production, aggregation of the dispersion over time can be prevented, and when forming the surface layer, it can be applied without dissolving the lower layer already formed on the conductive support, Even during coating and drying, there is little aggregation of the fluororesin fine particles, and a surface layer having uniform dispersibility can be formed.

  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 fluororesin fine particles are dispersed is advantageously applied 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 device, 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. Furthermore, when multiple layers with different properties and dissolved in the same solvent are formed, the time in the solvent is much shorter compared to the dip coating method, so that the lower layer component hardly elutes to the upper layer side, and the coating tank Can be applied without degrading the dispersibility of the fluororesin fine particles.

  The fluorine-containing resin fine particles of the present invention have an average primary particle size of 0.02 μm or more and less than 0.20 μm. However, if the average primary particle size is less than 0.02 μm, the stability of the dispersion deteriorates, and the fluorine-containing resin fine particles Aggregation occurs between each other, it is difficult to uniformly disperse, contact angle variation is likely to increase, and the dash mark described above is likely to occur. Further, if the average primary particle size is larger than 0.20 μm, aggregated particles are likely to be formed due to sedimentation, the variation in the contact angle of the surface is increased, and a dash mark is easily generated and at the same time, image exposure such as laser light is scattered, Deteriorates sharpness.

In this specification, the average primary particle diameter is a value measured by DLS-6000 (manufactured by Otsuka Electronics Co., Ltd.) using a dynamic light scattering method. However, it does not have to be measured by the above apparatus, and may be measured by any apparatus as long as it can be measured by the same principle as that of the above apparatus or by laser diffraction method and centrifugal sedimentation method. If the same measurement as in the above apparatus is possible, it may be measured by observing the cross section of the photosensitive layer. If the contact angle of the surface layer with respect to water is less than 90 °, an inorganic external additive such as silica in the toner. Adhesion increases and dash marks are likely to occur. Further, the frictional resistance with the contact member of the photosensitive member such as a cleaning blade is large, wear due to scratching is increased, streaky image unevenness is generated, and sharpness is easily deteriorated. A more preferable contact angle is 95 ° or more and 120 ° or less. If the contact angle is made larger than 120 °, the content of the fluororesin fine particles in the surface layer becomes too high, the surface layer becomes soft, and scratches are easily generated, and image blur is likely to occur. Further, if the variation in the contact angle of the surface layer is larger than ± 2.0 °, the dispersibility of the fluororesin fine particles in the surface layer is not uniform, and an inorganic component in the toner or paper powder, for example, toner Inorganic external additives such as silica and titanium oxide in the inside, talc components in paper powder and the like are embedded in the surface layer, and a dash mark is likely to occur. Also, black stripes and white stripes are likely to occur. The variation in contact angle is more preferably ± 1.7 °.

Measurement of Contact Angle and Contact Angle Variation The contact angle of the present invention refers to the contact angle of pure water on the surface of the photoreceptor. The contact angle of the photoreceptor is measured with a contact angle meter (CA-DT • A type: manufactured by Kyowa Interface Science Co., Ltd.) in an environment of 20 ° C. and 50% RH.

  The contact angle variation is measured in an environment of 20 ° C. and 50% RH. The measurement is performed when the photoreceptor is sufficiently familiar with image formation (after forming at least several printed images). When the photoconductor is cylindrical, measure the four locations at 90 ° in the circumferential direction at three locations, 5 cm from the center and the left and right ends, for a total of 12 locations. The contact angle according to the present invention was used, and the value that was the largest or most negative from this average value was determined as the variation value. In the case where the photosensitive member is a sheet, similarly, at the three positions of 5 cm from the central portion and the left and right end portions, four locations are measured at equal intervals, and a total of 12 locations are measured. The contact angle was defined as the variation value, which was the largest deviation from the average value in the positive or negative direction.

  The fluororesin fine particles have an average primary particle size of 0.02 μm or more and less than 0.20 μm and a crystallinity of less than 90%. When the crystallinity is 90% or more, the dispersibility of the fluorine-containing resin fine particles is improved, but the spreadability of the fluorine-containing resin fine particles themselves becomes small, and the variation in the contact angle tends to increase. The lower limit of the crystallinity is not particularly limited as long as the object of the present invention is achieved, but if the crystallinity of the fluororesin fine particles is too small, the extensibility becomes excessive and the dispersibility is low. From the viewpoint of easy deterioration, fluorine-containing resin fine particles having a crystallinity of 40% or more are preferable.

  The crystallinity of the fluororesin fine particles is measured by wide-angle X-ray diffraction measurement. The generated diffraction peak is separated into crystalline and amorphous, and after correcting the baseline, the crystalline and amorphous total X It is expressed as a percentage (%) of the X-ray integral intensity (numerator) of the crystalline with respect to the line integral intensity (denominator).

  In the present invention, the wide-angle X-ray diffraction measurement device and the measurement conditions were measured as follows, but other measurement devices and the like may be used as long as the same result is obtained.

X-ray generator: Rigaku RU-200B
Output: 50kV, 150mA
Monochromator: Graphite Radiation source: CuKα (0.154184 nm)
Scanning range: 3 ° ≦ 2θ ≦ 60 °
Scanning method: θ-2θ
Scanning speed: 2 ° / min
The constituent material of the fluorine-containing resin fine particles is a homopolymer or copolymer of a fluorine-containing polymerizable monomer, or a copolymer of a fluorine-containing polymerizable monomer and a fluorine-free polymerizable monomer. The fluorine-containing polymerizable monomer has the general formula (3);

(In General Formula (3), at least one group of R ^{4 to} R ⁷ is a fluorine atom, and the remaining groups are each independently a hydrogen atom, a chlorine atom, a methyl group, a monofluoromethyl group, a difluoromethyl group. Or a trifluoromethyl group). Preferable fluorine-containing polymerizable monomers include ethylene tetrafluoride, ethylene trifluoride, ethylene trifluoride chloride, propylene hexafluoride, vinyl fluoride, vinylidene fluoride, ethylene difluoride dichloride and the like. Two or more types of monomers may be used as the fluorine-containing polymerizable monomer.

  Examples of the fluorine-free polymerizable monomer include vinyl chloride. Two or more types of monomers may be used as the fluorine-free polymerizable monomer.

  All of the fluororesin fine particles are preferably made of a homopolymer or copolymer of a fluoropolymerizable monomer among the above-mentioned constituent materials, more preferably polytetrafluoroethylene (PTFE) or polytrifluoride. Ethylene, ethylene tetrafluoride-hexafluoropropylene copolymer, polyvinylidene fluoride, especially polytetrafluoroethylene.

  The average molecular weight of the polymer constituting the fluorine-containing resin fine particles is not particularly limited as long as the object of the present invention can be achieved, but usually the range of 10,000 to 1,000,000 is preferable.

  The crystallinity of the fluororesin fine particles of the present invention varies depending on the constituent material of the fluororesin fine particles, but can also be changed by heat-treating the fluororesin fine particles. For example, when PTFE fine particles (polyethylene terephthalate fine particles) having an average primary particle size of 0.12 μm and a crystallinity of 91.3 are heat-treated at 250 ° C. for 65 minutes, the crystallinity can be reduced to 82.8. The heat treatment means is not particularly limited, and a known dryer or heating furnace can be used.

  As the binder resin in the surface layer, it is preferable to use a resin having a surface active group that assists the dispersibility of the fluorine-containing resin fine particles in the resin partial structure. For example, a polycarbonate or polyarylate having a siloxane group in the partial structure is used. preferable. In particular, a siloxane-modified polycarbonate having a siloxane group shown below in a partial structure is preferable.

  The molecular weight is preferably 10,000 to 100,000.

  In order to form a surface layer having a contact angle with water of 90 ° or more and a variation in contact angle of ± 2.0 ° using the fluorine-containing resin fine particles of the present invention, the fluorine-containing resin in the surface layer is used. It is preferable to increase the ratio of the fine particles, and it is preferable to use at least 20 parts by mass and 200 parts by mass with respect to 100 parts by mass of the binder resin. If it is less than 20 parts by mass, it is difficult to form a surface layer that simultaneously satisfies a contact angle of 90 ° or more and a contact angle variation of ± 2.0 °, and if it exceeds 200 parts by mass, the surface layer becomes a fragile film, Scratches are likely to occur.

  The surface layer of the present invention is characterized in that a compound represented by the general formula (1) is used as a carrier transport material as a charge transport material.

  In the surface layer of the present invention, the compound represented by the general formula (2) is used as a carrier transport material as a charge transport material.

  Each of the charge transport materials of the general formula (1) and the general formula (2) improves the dispersibility of the fluorine-containing resin fine particles, forms a surface layer with a small contact angle variation and a uniform adhesion of foreign matter, It is possible to prevent the occurrence of dash marks, image unevenness and image blur, and to have stable potential characteristics that hardly cause transfer memory. Further, the charge transport materials of the general formula (1) and the general formula (2) can be used in combination so that more preferable effects can be exhibited.

  Specific examples of the compound of the general formula (1) are listed below, but the present invention is not limited to the specific examples.

  Specific examples of the compound of the general formula (2) are listed below, but the present invention is not limited to the specific examples.

  The mass ratio of the binder resin and the charge transport material in the surface layer is preferably 30 to 200 parts by mass, 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. 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” 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”, “Tinubin 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 characteristics are 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 agglomerated particles. Likely to happen. 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 image irregularities are likely to occur through these large irregularities. Further, the N-type semiconducting particles having a number average primary particle size of greater than 200 nm are likely to precipitate in the dispersion and easily generate aggregates. As a result, image unevenness is likely to occur.

  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. That is, the electron mobility is increased, the charging potential is stabilized, the residual potential is prevented from increasing, and the generation of the transfer memory can be prevented. .

  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 in producing a good halftone image.

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.

  Further, the N-type semiconductive particles may be those surface-treated with a reactive organosilicon compound represented by the following formula.

(R) _n -Si- (X) _4-n
(In the above formula, Si represents a silicon atom, R represents an organic group in which carbon is directly bonded to the silicon atom, X represents a hydrolyzable group, and n represents an integer of 0 to 3).
In the organosilicon compound represented by the above formula, the organic group in which carbon is directly bonded to the silicon represented by R includes alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, octyl and dodecyl, phenyl , Aryl groups such as tolyl, naphthyl and biphenyl, epoxy-containing groups such as γ-glycidoxypropyl and β- (3,4-epoxycyclohexyl) ethyl, γ-acryloxypropyl and γ-methacryloxypropyl ( (Meth) acryloyl group, hydroxyl group such as γ-hydroxypropyl, 2,3-dihydroxypropyloxypropyl, vinyl group such as vinyl and propenyl, mercapto group such as γ-mercaptopropyl, γ-aminopropyl, N-β Amino-containing groups such as (aminoethyl) -γ-aminopropyl, γ-chloropropyl, 1,1, - trifluoride Oro propyl, nonafluorohexyl, halogen-containing groups such as perfluorooctylethyl, other nitro, and cyano-substituted alkyl group. Examples of the hydrolyzable group for X include alkoxy groups such as methoxy and ethoxy, halogen groups, and acyloxy groups.

  Moreover, the organosilicon compound represented by the above formula may be used alone or in combination of two or more.

  Further, in the case of a specific compound of an organosilicon compound represented by the above formula and n is 2 or more, a plurality of R may be the same or different. Similarly, when n is 2 or less, the plurality of Xs may be the same or different. Moreover, when using 2 or more types of organosilicon compounds represented by the above formula, R and X may be the same or different between the respective compounds.

  Further, prior to the surface treatment of the methylhydrogensiloxane copolymer or the reactive organosilicon compound, the N-type semiconductive particles may be subjected to an inorganic surface treatment such as alumina or silica.

  In addition, although the above-mentioned treatment of alumina and silica may be performed simultaneously, it is preferable to perform the alumina treatment first and then the silica treatment. Further, the amount of treatment of alumina and silica when treating alumina and silica is preferably higher than that of alumina.

  The surface treatment of the N-type semiconductive fine particles such as titanium oxide with a metal oxide such as alumina, silica or zirconia can be performed by a wet method. For example, N-type semiconductive particles subjected to silica or alumina surface treatment can be prepared as follows.

  When titanium oxide particles are used as the N-type semiconductive particles, titanium oxide particles (number average primary particle size: 50 nm) are dispersed in water at a concentration of 50 to 350 g / L to form an aqueous slurry. Add acid salt or water-soluble aluminum compound. Thereafter, alkali or acid is added for neutralization, and silica or alumina is precipitated on the surface of the titanium oxide particles. Subsequently, filtration, washing, and drying are performed to obtain the target surface-treated titanium oxide. When sodium silicate is used as the water-soluble silicate, it can be neutralized with an acid such as sulfuric acid, nitric acid or hydrochloric acid. On the other hand, when aluminum sulfate is used as the water-soluble aluminum compound, it can be neutralized with an alkali such as sodium hydroxide or potassium hydroxide.

  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 rectifying property of the intermediate layer is increased, and no increase in residual potential or transfer memory occurs even when the film thickness is increased. Therefore, it is possible to effectively prevent black spots and to form a good organic photoreceptor with a small potential fluctuation. 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 halftone 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.
Black spots are likely to occur and halftone images are 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 (4), 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 (5), and the number of carbons contained in Y and the number of carbons contained in Z are the number of amide bond units in the repeating unit structure.

In general formula (4), 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 (5), 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%.

  When the carbon number is less than 7, the hygroscopicity of the polyamide resin is large, the electrophotographic characteristics, particularly the humidity dependency of the potential during repeated use is large, and image defects such as black spots are likely to occur, and the halftone image is Easy 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 (6).

In General Formula (6), 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 (6), 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 the occurrence of image unevenness in black spots and halftone images.

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 (6) 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 liable to be reduced, and an agglomerated resin is likely to be generated in the intermediate layer, and image unevenness is likely to occur in black spots and halftone images.

  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, image unevenness is likely to occur in black spots and halftone images, and if it exceeds 10 μm, residual potential is increased and transfer memory is likely to occur, and sharpness is likely 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 to be 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 The charge generation layer contains a charge generation material (CGM). Other substances may contain a binder resin and other additives as necessary.

  A gallium phthalocyanine pigment is preferably used in the charge generation layer of the present invention. Gallium phthalocyanine pigments have high sensitivity when used in organic photoreceptors, but transfer memories are likely to occur as described above. In the present invention, the problem of such a high-sensitivity gallium phthalocyanine pigment can be solved by the combination with the charge transport layer described above. That is, when the charge generation layer using the high-sensitivity gallium phthalocyanine pigment and the charge transport layer containing the charge transport material of the general formula (1) or (2) are stacked, the interface between the charge generation layer and the charge transport layer is obtained. It is considered that the charge transfer barrier becomes smaller and the charge accumulation of transfer charge becomes smaller.

  As the gallium phthalocyanine pigment preferably used in the present invention, at a Bragg angle (2θ ± 0.2 °) of the characteristic X-ray diffraction spectrum of Cu—Kα, at least 7.4 °, 16.6 °, 25.5 °, Chlorgallium phthalocyanine pigment having a characteristic diffraction peak at a position of 28.3 °, at least 7.5 °, 9.9 °, 12.5 °, 16.3 °, 18.6 °, 25.1 °, Hydroxygallium phthalocyanine pigment having a characteristic diffraction peak at 28.1 ° and gallium having characteristic diffraction peaks at least at 6.8 °, 12.8 °, 15.8 °, 26.6 ° Phthalocyanine pigments are preferred. By combining the charge generation layer containing a gallium phthalocyanine pigment having such an X-ray diffraction spectrum and the charge transport material of the present invention, image irregularity and image blur due to dash marks and scratches or transfer memory can be realized with high sensitivity. And an excellent electrophotographic image can be provided.

  In addition to the gallium phthalocyanine pigment, a known charge generating material (CGM) can be used in combination if necessary. For example, phthalocyanine pigments other than gallium phthalocyanine pigments, azo pigments, perylene pigments, azulenium pigments, and the like can be used. However, a gallium phthalocyanine pigment is preferred as the main charge generating substance.

  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 0.01 μm to 1 μm. If the thickness is less than 0.01 μm, sufficient sensitivity characteristics cannot be obtained, and the residual potential tends to increase. On the other hand, even if the thickness exceeds 1 μm, the sensitivity tends to decrease and a transfer memory tends to occur.

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 fluorine-based resin particles.

  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 above-described fluororesin particles as necessary.

  As the charge transport material (CTM), in addition to the charge transport material of the general formula (1) or the general formula (2), a known hole transport property (P-type) charge transport material (CTM) is used if necessary. You can also. 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.

  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 pleated 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 an organic photoreceptor, a coating processing method such as dip coating or spray coating is used in addition to the above-described slide hopper type coating device. The surface layer is most preferably the circular slide hopper type coating device.

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

  An image forming apparatus 1 shown in FIG. 3 is a digital image forming apparatus, and includes an image reading unit A, an image processing unit B, an image forming unit C, and a transfer paper transport unit D as a transfer paper transport unit. Yes.

  An automatic document feeder that automatically conveys the document is provided above the image reading unit A. The document placed on the document table 11 is separated and conveyed by the document conveyance roller 12 to the reading position 13a. The image is read. The document after the document reading is completed is discharged onto the document discharge tray 14 by the document transport roller 12.

  On the other hand, the image of the original when placed on the platen glass 13 is read at a speed v of the first mirror unit 15 including the illumination lamp and the first mirror constituting the scanning optical system, and the V-shaped first image is located. Reading is performed by the movement of the second mirror unit 16 including the two mirrors and the third mirror in the same direction at the speed v / 2.

  The read image is formed on the light receiving surface of the image sensor CCD, which is a line sensor, through the projection lens 17. The line-shaped optical image formed on the image sensor CCD is sequentially photoelectrically converted into an electric signal (luminance signal) and then A / D converted, and the image processing unit B performs processing such as density conversion and filter processing. Then, the image data is temporarily stored in the memory.

  In the image forming unit C, as an image forming unit, a drum-shaped photoconductor 21 as an image carrier, a charging means (charging step) 22 for charging the photoconductor 21 on the outer periphery thereof, and a surface potential of the charged photoconductor. Potential detecting means 220 for detecting the color, developing means (development process) 23, transfer / conveying belt device 45 as transfer means (transfer process), cleaning device (cleaning process) 26 for the photosensitive member 21, and photostatic means (photo-site charge). PCLs (precharge lamps) 27 as generating steps) are arranged in the order of operation. Further, on the downstream side of the developing means 23, a reflection density detecting means 222 for measuring the reflection density of the patch image developed on the photosensitive member 21 is provided. The photoconductor 21 uses the organic photoconductor of the present invention and is driven to rotate in the clockwise direction shown in the figure.

  After the rotating photosensitive member 21 is uniformly charged by the charging unit 22, an image based on an image signal called from the memory of the image processing unit B by an exposure optical system as an image exposure unit (image exposure step) 30 is used. Exposure is performed. The exposure optical system as the image exposure means 30 serving as a writing means uses a laser diode (not shown) as a light source, passes through a rotating polygon mirror 31, an fθ lens 34, and a cylindrical lens 35, and the optical path is bent by the reflection mirror 32 to perform main scanning. Therefore, image exposure is performed on the photoconductor 21 at the position Ao, and an electrostatic latent image is formed by rotation (sub-scanning) of the photoconductor 21. In one example of the present embodiment, the character portion is exposed to form an electrostatic latent image.

In the image forming method of the present invention, when an electrostatic latent image is formed on a photoreceptor, it is preferable to perform image exposure using an exposure beam having a spot area of 2 × 10 ⁻⁹ m ² or less. Even when such small-diameter beam exposure is performed, the organic photoreceptor of the present invention can faithfully form an image corresponding to the spot area. A more preferable spot area is 0.01 × 10 ⁻⁹ to 1 × 10 ⁻⁹ m ² . As a result, it is possible to achieve extremely excellent image quality that achieves 256 gradations at 400 dpi (dpi: the number of dots per 2.54 cm) or more.

The spot area of the exposure beam is represented by an area corresponding to a light intensity at which the intensity of the beam light is 1 / e ² or more of the peak intensity.

The exposure beam used includes a scanning optical system using a semiconductor laser, and a solid state scanner such as an LED or a liquid crystal shutter. The light intensity distribution includes a Gaussian distribution and a Lorentz distribution, but 1 / e of each peak intensity. ^The area up to ² is the spot area.

  The electrostatic latent image on the photoconductor 21 is reversely developed by the developing unit 23, and a visible toner image is formed on the surface of the photoconductor 21. In the image forming method of the present invention, a polymerized toner is used as a developer used in the developing unit. By using a polymerized toner having a uniform shape and particle size distribution in combination with the organic photoreceptor of the present invention, an electrophotographic image with better sharpness can be obtained.

  Here, the polymerized toner means a toner obtained by forming a resin for a toner binder and forming the toner shape by polymerization of a raw material monomer of the binder resin and subsequent chemical treatment. More specifically, it means a toner obtained through a polymerization reaction such as suspension polymerization or emulsion polymerization and, if necessary, a subsequent step of fusing particles.

  Since the polymerized toner is produced by uniformly dispersing the raw material monomers in an aqueous system and then producing the toner, a toner having a uniform toner particle size distribution and shape can be obtained.

  The polymerized toner is produced by emulsion polymerization of monomers in a suspension polymerization method or in a solution to which an emulsion of necessary additives is added to produce fine polymer particles, and then an organic solvent, an aggregating agent, etc. It can manufacture by the method of adding and associating. A method of preparing by mixing with a dispersion liquid such as a release agent and a colorant necessary for the composition of the toner at the time of association, and a toner component such as a release agent and a colorant dispersed in the monomer And a method of emulsion polymerization. Here, the association means that a plurality of resin particles and colorant particles are fused.

  That is, various constituent materials such as a colorant and, if necessary, a release agent, a charge control agent, and a polymerization initiator are added to the polymerizable monomer, and a homogenizer, a sand mill, a sand grinder, an ultrasonic disperser, etc. Various constituent materials are dissolved or dispersed in the polymerizable monomer. The polymerizable monomer in which these various constituent materials are dissolved or dispersed is dispersed in oil droplets having a desired size as a toner in an aqueous medium containing a dispersion stabilizer using a homomixer or a homogenizer. Thereafter, the stirring mechanism is transferred to a reaction apparatus which is a stirring blade described later, and the polymerization reaction is advanced by heating. After completion of the reaction, the dispersion stabilizer is removed, filtered, washed, and dried to prepare a toner.

  Further, as a method for producing the toner of the present invention, a method of preparing by associating or fusing resin particles in an aqueous medium can also be mentioned. The method is not particularly limited, and examples thereof include methods disclosed in JP-A-5-265252, JP-A-6-329947, and JP-A-9-15904. That is, a method of associating a plurality of fine particles composed of resin particles and colorants, etc., or particles composed of resin and colorant, in particular, after dispersing them in water using an emulsifier, the critical aggregation concentration The above flocculant is added for salting out, and at the same time, the formed polymer itself is heated and fused at a temperature higher than the glass transition temperature to gradually grow the particle size while forming fused particles. Then, a large amount of water was added to stop the particle size growth, and the particle surface was smoothed while heating and stirring to control the shape, and the particles were heated and dried in a fluidized state while containing water, whereby a toner was obtained. Can be formed. Here, an organic solvent that is infinitely soluble in water may be added simultaneously with the flocculant.

  Note that materials and manufacturing methods for producing a uniform toner such as a shape factor used in the present invention, a polymerization toner reaction device, and the like are described in detail in JP-A-2000-214629.

  In the transfer paper transport section D, paper feed units 41 (A), 41 (B), and 41 (C) are provided below the image forming unit as transfer paper storage means for storing transfer paper P of different sizes. Further, a manual paper feeding unit 42 for manually feeding paper is provided on the side, and the transfer paper P selected from any of them is fed along the transport path 40 by the guide roller 43 and fed. The transfer paper P is temporarily stopped by a pair of paper feed registration rollers 44 that correct the inclination and bias of the transfer paper P to be transferred, and then fed again. The transport path 40, the pre-transfer roller 43a, and the paper feed path 46 The toner image on the photosensitive member 21 is transferred to the transfer paper P while being transferred to the transfer conveyance belt 454 of the transfer conveyance belt device 45 by the transfer electrode 24 and the separation electrode 25 at the transfer position Bo. Is, transfer sheet P is separated from the photosensitive member 21 surface, it is conveyed to the fixing unit 50 by the transfer conveyor belt device 45.

  The fixing unit 50 includes a fixing roller 51 and a pressure roller 52. By passing the transfer paper P between the fixing roller 51 and the pressure roller 52, the toner is fixed by heating and pressing. After the toner image has been fixed, the transfer paper P is discharged onto the paper discharge tray 64.

  The above describes the state in which image formation is performed on one side of the transfer paper. However, in the case of double-sided copying, the paper discharge switching member 170 is switched, the transfer paper guide 177 is opened, and the transfer paper P is indicated by a broken arrow. Conveyed in the direction.

  Further, the transfer paper P is transported downward by the transport mechanism 178 and switched back by the transfer paper reversing unit 179, and the rear end portion of the transfer paper P becomes the leading end portion and transported into the duplex copying paper supply unit 130. The

  The transfer paper P is moved in a paper feed direction by a conveyance guide 131 provided in the double-sided copy paper supply unit 130, the transfer paper P is re-fed by the paper supply roller 132, and the transfer paper P is guided to the conveyance path 40. .

  Again, as described above, the transfer paper P is conveyed in the direction of the photosensitive member 21, the toner image is transferred to the back surface of the transfer paper P, fixed by the fixing unit 50, and then discharged onto the paper discharge tray 64.

  The image forming apparatus of the present invention is configured by integrally combining the above-described photosensitive member and components such as a developing device and a cleaning device as a process cartridge, and this unit is configured to be detachable from the apparatus main body. Also good. In addition, a process cartridge is formed by integrally supporting at least one of a charger, an image exposure device, a developing device, a transfer or separation device, and a cleaning device together with a photosensitive member, and a single unit that is detachable from the apparatus main body. It is good also as a structure which can be attached or detached using guide means, such as a rail of an apparatus main body.

  Next, FIG. 4 shows a color image forming apparatus using the organic photoreceptor of the present invention (a copying machine having at least a charging means, an exposure means, a plurality of developing means, a transfer means, a cleaning means and an intermediate transfer body around the organic photoreceptor. 1 is a sectional view of the configuration of a laser beam printer). The belt-shaped intermediate transfer body 10 uses an elastic body having a medium resistance.

  Reference numeral 21 denotes a rotary drum type photoconductor that is repeatedly used as an image forming body, and is rotated at a predetermined peripheral speed in the counterclockwise direction indicated by an arrow.

  In the rotation process, the photosensitive member 21 is uniformly charged to a predetermined polarity and potential by the charging unit 22, and then modulated by the image exposure unit 30 (not shown) corresponding to the time-series electric digital pixel signal of the image information. An electrostatic latent image corresponding to a yellow (Y) color component image of a target color image is formed by receiving image exposure with scanning exposure light or the like by a laser beam.

  Next, the electrostatic latent image is developed with yellow toner which is the first color by yellow (Y) developing means (yellow color developing device) 23Y. At this time, the second to fourth developing means (magenta developer, cyan developer, black developer) 23M, 23C, and 23Bk are turned off and do not act on the photosensitive member 21. The first color yellow toner image is not affected by the second to fourth developing units.

  The intermediate transfer member 70 is stretched by rollers 79a, 79b, 79c, 79d, and 79e, and is rotationally driven in the clockwise direction at the same peripheral speed as the photosensitive member 21.

  The yellow toner image of the first color formed and supported on the photoreceptor 21 is applied to the intermediate transfer body 70 from the primary transfer roller 24a in the process of passing through the nip portion between the photoreceptor 1 and the intermediate transfer body 70. The intermediate transfer (primary transfer) is sequentially performed on the outer peripheral surface of the intermediate transfer body 70 by the electric field formed by the primary transfer bias.

  The surface of the photoconductor 21 after the transfer of the first color yellow toner image corresponding to the intermediate transfer body 70 is cleaned by the cleaning device 26.

  Similarly, the second color magenta toner image, the third color cyan toner image, and the fourth color black (black) toner image are sequentially superimposed and transferred onto the intermediate transfer body 70 to correspond to the target color image. A superimposed color toner image is formed.

  The secondary transfer roller 24b is supported in parallel with the secondary transfer counter roller 79b so as to be separated from the lower surface of the intermediate transfer body 70.

  The primary transfer bias for sequentially superimposing and transferring the first to fourth color toner images from the photosensitive member 21 to the intermediate transfer member 70 has a polarity opposite to that of the toner and is applied from a bias power source. The applied voltage is, for example, in the range of +100 V to +2 kV.

  In the primary transfer process of the first to third color toner images from the photosensitive member 21 to the intermediate transfer member 70, the secondary transfer roller 24b and the intermediate transfer member cleaning means 26A can be separated from the intermediate transfer member 70. is there.

  When the superimposed color toner image transferred onto the belt-shaped intermediate transfer body 70 is transferred to the transfer material P, which is the second image carrier, the secondary transfer roller 24b is brought into contact with the belt of the intermediate transfer body 70. At the same time, the transfer material P is fed from the pair of paper supply registration rollers 44 through the transfer sheet guide to the belt of the intermediate transfer body 70 to the contact nip with the secondary transfer roller 24b at a predetermined timing. A secondary transfer bias is applied to the secondary transfer roller 24b from a bias power source. By this secondary transfer bias, the superimposed color toner image is transferred (secondary transfer) from the intermediate transfer body 70 to the transfer material P as the second image carrier. The transfer material P that has received the transfer of the toner image is introduced into the fixing means 50 and fixed by heating.

  The organophotoreceptor of the present invention is generally applicable to electrophotographic apparatuses such as electrophotographic copying machines, laser printers, LED printers, and liquid crystal shutter printers, but further displays, recordings, light printing, plate making and facsimiles using electrophotographic technology. The present invention can be widely applied to such devices.

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

Example 1 (Example corresponding to claim 1)
A photoreceptor used for evaluation was produced as follows.

Preparation of photoreceptor 1 Intermediate layer 1
The following intermediate layer coating solution was applied by a dip coating method on a washed cylindrical aluminum substrate (processed to 10-point surface roughness Rz: 0.81 μm as defined in JISB-0601 by cutting) at 120 ° C. for 30 minutes. It dried and formed the intermediate | middle layer 1 with a dry film thickness of 1.0 micrometer.

  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 (1.00 volume part)
2. Rutile-type titanium oxide A1 (primary particle size 35 nm; a surface treatment using a copolymer of methylhydrogensiloxane and dimethylsiloxane (molar ratio 1: 1) in an amount of 5% by mass of the total mass of titanium oxide) 5 parts (1.0 part by volume)
Ethanol / n-propyl alcohol / THF (= 45/20/30 mass ratio) 10 parts The above components were mixed and dispersed in a batch system for 10 hours using a sand mill disperser to prepare an intermediate layer dispersion. .

Charge generation layer The following components were mixed and dispersed using a sand mill disperser to prepare a charge generation layer coating solution. This coating solution was applied by a dip coating method to form a charge generation layer having a dry film thickness of 0.3 μm on the intermediate layer.

Hydroxygallium phthalocyanine pigment (at the Bragg angle (2θ ± 0.2 °) of the characteristic X-ray diffraction spectrum of Cu-Kα, at least 7.5 °, 9.9 °, 12.5 °, 16.3 °, 18. Hydroxygallium phthalocyanine pigment having characteristic diffraction peaks at 6 °, 25.1 °, and 28.1 °) 20 parts Silicone-modified polyvinyl butyral 10 parts 4-methoxy-4-methyl-2-pentanone 700 parts t- Butyl acetate 300 parts <Charge transport layer 1 (CTL1)>
Charge transport material (CT1-3) 225 parts Polycarbonate (Z300: manufactured by Mitsubishi Gas Chemical Company) 300 parts Antioxidant (Exemplary Compound 2-1) 6 parts Dichloromethane 2000 parts Silicon oil (KF-54: Shinetsu Chemical Co., Ltd.) 1 Parts were 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.

<Preparation of polytetrafluoroethylene resin particle (PTFE particle) dispersion>
PTFE particles (PTFE particles having an average primary particle size of 0.12 μm and a crystallinity of 91.3) were heat-treated at 250 ° C. for 40 minutes, and PTFE particles having a crystallinity of 82.8 were used. A liquid was prepared.

PTFE particles (PT1: average primary particle size 0.12 μm, crystallinity 82.8) 200 parts Toluene 600 parts Fluorine comb type graft polymer (trade name GF300, manufactured by Toagosei Co., Ltd.) 15 parts were mixed. After that, a PTFE particle dispersion was prepared by dispersing with a sand grinder (made by Amex Co., Ltd.) using glass beads.

<Charge transport layer 2 (CTL2)>
PTFE particle dispersion 815 parts Charge transport material (CT1-3) 150 parts Siloxane-modified polycarbonate resin (PC-1) 150 parts Polycarbonate (Z300: manufactured by Mitsubishi Gas Chemical Company) 150 parts Antioxidant (Exemplary Compound 1-1) 12 Part THF: Tetrahydrofuran 2800 parts Silicon oil (KF-54: manufactured by Shin-Etsu Chemical Co., Ltd.) 4 parts were mixed 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 type coater, dried at 110 ° C. for 70 minutes to form a charge transport layer 2 (surface layer) having a dry film thickness of 2.0 μm, Photoconductor 1 was produced.

Preparation of photoconductors 2 to 13 N-type semiconductive particles in the intermediate layer, binder resin, dry film thickness, charge generation material, charge transport material in charge transport layers 1 and 2, and fluorine resin in charge transport layer 2 (CTL2) Photoconductors 2 to 13 were produced in the same manner as the photoconductor 1 except that the type and addition amount of the particles were changed as shown in Table 1.

In Table 1,
The intermediate layer no. The contents of are shown in Table 2.

  In Table 1, G1, G2, and G3 represent the following charge generating substances.

G1 is at least 7.5 °, 9.9 °, 12.5 °, 16.3 °, 18.6 ° in the Bragg angle (2θ ± 0.2 °) of the characteristic X-ray diffraction spectrum of Cu—Kα, Hydroxygallium phthalocyanine pigment G2 having characteristic diffraction peaks at positions of 25.1 ° and 28.1 ° G2 is at least 7. in the Bragg angle (2θ ± 0.2 °) of the characteristic X-ray diffraction spectrum of Cu-Kα. Chlorgallium phthalocyanine pigment having characteristic diffraction peaks at positions of 4 °, 16.6 °, 25.5 °, 28.3 ° G3 is a Bragg angle (2θ ± 0. 0.) of the characteristic X-ray diffraction spectrum of Cu-Kα. 2 °) gallium phthalocyanine pigment having characteristic diffraction peaks at positions of at least 6.8 °, 12.8 °, 15.8 °, and 26.6 ° In Table 1, * 1 indicates a charge transport material mixed Use (CT1-2 / T2-2 used in a weight ratio 6/2 a)
The structural formula of the charge transport material CR in Table 1 is shown below.

  PTFE and H represent the following fluororesin fine particles.

PTFE: Polyethylene terephthalate resin particles H: Copolymer resin particles of ethylene trifluoride-tetrafluoroethylene Further, the contact angle and the variation in the contact angle in Table 1 were measured by the above-described method and expressed as absolute values.

  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 Z is zinc 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, surface treatment refers to the material used for the surface treatment applied to the surface of the particles (however, silica / alumina in the primary treatment is silica / alumina deposited on the particle surface) Means).

  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>
The obtained photoreceptor was mounted on a commercially available color printer, magiccolor 2300 Desk Laser (manufactured by Minolta EMS), and an endurance test was conducted at low temperature and low humidity (LL: 10 ° C., 20% RH). Specifically, a total of 20,000 image images in which the character ratio, halftone image, solid white image, and solid black image with a pixel rate of 7% are divided into quarters are printed, and evaluated at the start and every 5000 images. did. Evaluation items and evaluation criteria are shown below.

  The process conditions for the color printer were as follows.

Charger: Sawtooth electrode Exposure device: Semiconductor laser Development: Nonmagnetic polymerized toner having an average particle diameter of 6.5 μm and containing 0.3 μm of strontium titanate and 15 nm of hydrophobic silica, reversal development method Transfer: Use of intermediate transfer belt Cleaning: Cleaning blade Fixing: Heat fixing Process speed: 100mm / sec
Image density Measured using a 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. Measurements were taken at the solid black image portion after each 20,000 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)
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 20,000 copies were made.

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)
Dash Mark The state of occurrence of a dash mark (small comet-like streak image) whose periodicity coincides with the period of the photoreceptor on the halftone image was determined according to the following criteria.

A: Frequency of dash marks of 0.4 mm or more: All printed images are 5 / A4 or less (good)
O: Frequency of dash marks of 0.4 mm or more: 1 or more of 6 / A4 or more and 10 / A4 or less (no problem in practical use)
X: Frequency of dash mark image defects of 0.4 mm or more: 11 or more A4 or more occurred (practical problem)
Image unevenness ◎: No streak-like unevenness was observed in any of the half images that coincided with the scratches on the surface of the photoreceptor through the printing of 20,000 sheets;
○: A slight streak-like unevenness was observed on a part of the surface of the photoreceptor through printing 20,000 sheets, but no streak-like unevenness was observed in the half image;
X: During printing of 20,000 sheets, clear streak-like unevenness was seen on the entire surface of the half image that coincided with the scratches on the surface of the photoreceptor.

Image blur ◎: No image blur occurred at all after printing 20,000 sheets (good)
○: Several partial image blurs (less than 10) occurred through printing 20,000 sheets, but there was no practical problem (no problem in practical use)
X: During printing of 20,000 sheets, 10 or more partial image blurs or 1 or more image blurs occurred over a wide range (practically problematic)
Transfer memory 10 images with a mixture of solid black and solid white are continuously printed, and then a uniform halftone image is printed, and the solid black and solid white history appears in the halftone image ( Judgment was made based on whether or not memory was generated (no memory was generated).

  ○: No memory is generated.

  ×: Memory is generated.

Sharpness Image sharpness was evaluated by crushing characters. Character images with different character sizes (points) were formed and evaluated according to the following criteria.

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)

  From Table 3, the charge transport material represented by the general formula (1) and fluororesin fine particles having an average primary particle size of 0.02 μm or more and less than 0.20 μm and a crystallinity of less than 90% are contained. Organic photoreceptors 1-3, 6, 8, 10-12 having a surface layer (= charge transport layer 2) having a contact angle with water of 90 ° or more and a variation of contact angle of ± 2.0 ° are as follows: All of the photoreceptors have improved image density, fog, dash mark, image unevenness, image blur, transfer memory, and sharpness. On the other hand, the photoconductor 4 using PTFE-4 having an average primary particle size of 0.01 μm is inferior in dispersibility of the fluororesin fine particles on the surface layer, has a large contact angle variation of 2.2, and generates a dash mark. doing. Further, the photoreceptor 5 using PTFE-5 having an average primary particle size of 0.22 μm also has a large contact angle variation of 2.3 on the surface layer, a dash mark is generated, and a lot of laser exposure is scattered. The sharpness is also deteriorated. In addition, the photoreceptor 7 using PTFE-7 having a crystallinity of 91.3 has a large contact angle variation of 2.2, and a dash mark is generated. In addition, the photoreceptor 9 in which the content of PTEF-1 is reduced in the surface layer (= charge transport layer 2) and the contact angle is lowered to 88 shows image unevenness and dash marks, and sharpness deteriorates. doing. Further, the photoreceptor 13 using the charge transport material other than the present invention has a large contact angle variation, dash marks, fog and transfer memory, and sharpness is deteriorated.

Example 2 (Example corresponding to claim 2)
Photoconductors 21 to 33 were prepared in the same manner except that the charge transport material of the charge transport layer of each photoconductor of Example 1 was changed as shown in Table 4. These photoreceptors 21 to 33 were evaluated in the same manner as in Example 1. The evaluation results are shown in Table 4.

  * 2 in Table 4 is a mixture of charge transport materials (CT2-2 / CT1-3 used at a mass ratio of 6/2)

  From Table 5, the charge transport material represented by the general formula (2), and fluorine-containing resin fine particles having an average primary particle size of 0.02 μm or more and less than 0.20 μm and a crystallinity of less than 90% are contained. And organic photoreceptors 21 to 23, 26, 28, and 30 to 32 having a surface layer (= charge transport layer 2) having a contact angle with water of 90 ° or more and a contact angle variation of ± 2.0 °. All of the photoreceptors have improved image density, fog, dash mark, image unevenness, image blur, transfer memory, and sharpness. On the other hand, the photoconductor 24 using PTFE-4 having an average primary particle size of 0.01 μm has poor dispersibility of the fluororesin fine particles on the surface layer, and the contact angle variation is as large as 2.2, resulting in a dash mark. doing. In addition, the photoreceptor 25 using PTFE-5 having an average primary particle size of 0.22 μm also has a large contact angle variation of 2.3 on the surface layer, a dash mark is generated, and a lot of laser exposure is scattered. The sharpness is also deteriorated. Further, the photoreceptor 27 using PTFE-7 having a crystallinity of 91.3 also has a large contact angle variation of 2.2, and a dash mark is generated. Further, the photoreceptor 29 in which the content of PTEF-1 is reduced in the surface layer (= charge transport layer 2) and the contact angle is lowered to 88 shows image unevenness and dash marks, and sharpness deteriorates. doing. Further, the photoreceptor 33 using the charge transport material other than the present invention has a large variation in contact angle, dash marks are generated, fog and transfer memory are frequently generated, and sharpness 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 schematic view in which functions of an image forming apparatus of the present invention are incorporated. 1 is a cross-sectional view of a color image forming apparatus using an organic photoreceptor of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 21 Photoconductor 22 Charging means 23 Developing means 24 Transfer pole 25 Separation pole 26 Cleaning device 30 Exposure optical system 45 Transfer conveyance belt apparatus 50 Fixing means 250 Separation claw unit

Claims (20)

In an organic photoreceptor having a photosensitive layer on a conductive support, the surface layer of the organic photoreceptor has a charge transport material represented by the following general formula (1), an average primary particle size of 0.02 μm or more, and 0.0. Organic containing fluorine-containing resin fine particles having a crystallinity of less than 90% less than 20 μm, a contact angle with water of 90 ° or more, and a variation in contact angle of ± 2.0 ° Photoconductor.

(In General Formula (1), Ar ₁ and Ar ₂ represent a substituted or unsubstituted aromatic ring group, R ₁ and R ₂ represent a hydrogen atom or an alkyl group, and R ₃ represents a hydrogen atom, an alkyl group, or a halogen atom. Represents an atom.) In an organic photoreceptor having a photosensitive layer on a conductive support, the surface layer of the organic photoreceptor has a charge transport material represented by the following general formula (2), an average primary particle size of 0.02 μm or more, and 0.0. Organic containing fluorine-containing resin fine particles having a crystallinity of less than 90% less than 20 μm, a contact angle with water of 90 ° or more, and a variation in contact angle of ± 2.0 ° Photoconductor.

(In General Formula (2), Ar ₁ and Ar ₂ represent a substituted or unsubstituted aromatic ring group, R ₄ represents a hydrogen atom, an alkyl group, or a halogen atom, and X represents a vinylene group or an ethylene group. ) The organic photoreceptor according to claim 1, wherein the surface layer contains a binder resin, and at least one of the binder resins is a siloxane-modified polycarbonate. The organophotoreceptor according to claim 1, wherein the fluororesin fine particles coexist with an antioxidant. The surface layer is an organic material having a boiling point of 120 ° C. or less under atmospheric pressure with a fluorine-containing resin fine particle and binder resin having at least an average primary particle size of 0.02 μm or more and less than 0.20 μm and a crystallinity of less than 90%. The organic photoreceptor according to any one of claims 1 to 4, wherein a coating liquid obtained by dispersing and dissolving in a solvent is applied by a coating liquid supply type coating apparatus. The organophotoreceptor according to claim 1, wherein the surface layer contains an antioxidant.   The organophotoreceptor according to claim 1, wherein the photosensitive layer has a structure in which a plurality of charge transport layers are stacked on a charge generation layer.   The organophotoreceptor according to claim 7, wherein the charge generation layer contains a gallium phthalocyanine pigment. 9. The organophotoreceptor according to claim 7, further comprising an intermediate layer containing N-type semiconductive particles between the conductive support and the charge generation layer. The organophotoreceptor according to claim 9, wherein the N-type semiconductor particles are a metal oxide. The organophotoreceptor according to claim 9 or 10, wherein the N-type semiconductor particles are titanium oxide or zinc oxide. The organophotoreceptor according to claim 11, wherein the N-type semiconductor particles are titanium oxide. The organophotoreceptor according to claim 12, wherein the titanium oxide is a rutile titanium oxide pigment or an anatase titanium oxide pigment. The organophotoreceptor according to claim 9, wherein the N-type semiconductor particles are subjected to a surface treatment. The organic photoreceptor according to any one of claims 9 to 14, wherein the intermediate layer contains a polyamide resin binder. 16. The organic photoreceptor according to claim 15, 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. The organic photoreceptor according to claim 15 or 16, wherein a 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. The organic photoreceptor according to claim 9, wherein the intermediate layer has a thickness of 1 to 10 μm. An organic photoreceptor and charging means for charging by bringing a charging member into contact with the organic photoreceptor, a developing means for visualizing an electrostatic latent image on the organic photoreceptor, and visualized on the organic photoreceptor Image forming apparatus comprising: transfer means for transferring a toner image onto a transfer material; charge eliminating means for removing charges on the organic photoreceptor after transfer; and cleaning means for removing residual toner on the organic photoreceptor after transfer A process cartridge for use in the present invention, wherein the organic photosensitive member according to any one of claims 1 to 18 and a charging unit, a latent image forming unit, a developing unit, a transferring unit, a discharging unit, and a cleaning unit are formed on the organic photosensitive unit. A process cartridge characterized in that at least one means is integrally supported and can be detachably attached to an image forming apparatus main body. An organic photoreceptor and charging means for charging by bringing a charging member into contact with the organic photoreceptor, a developing means for visualizing an electrostatic latent image on the organic photoreceptor, and visualized on the organic photoreceptor Image forming apparatus comprising: transfer means for transferring a toner image onto a transfer material; charge eliminating means for removing charges on the organic photoreceptor after transfer; and cleaning means for removing residual toner on the organic photoreceptor after transfer An image forming apparatus using the organic photoreceptor according to any one of claims 1 to 18.

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