JP2005338443A - Image forming device and method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming device and method capable of preventing dash marks, uneven images due to black stripes and white stripes or blurred images by developing an organic photoreceptor having a flat surface layer of low surface energy and forming electrophotographic images by using the above organic photoreceptor and toner having dispersion almost of single particles. <P>SOLUTION: The organic photoreceptor has a surface layer which contains 90% crystallized fluorinated carbon resin particles having a first average diameter of 0.02 μm or larger but smaller than 0.20 μm and binder resin, and has a contact angle 90° or larger to water with an error ±2.0°. The developing means uses the toner, 10% of which is the particles of 0.7×(Dp50) or smaller, when Dp50 represents the toner particle size for 50% of them in number. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus and an image forming method used for electrophotographic image formation, and more particularly to an image forming apparatus and an image forming method used for electrophotographic image formation used in the field of copying machines and printers. Is.

  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 image irregularities and image blurs due to dash marks (small comet-like streaks), black streaks and white streaks appear in the electrophotographic image, resulting in a problem that the image quality is significantly lowered. 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 a 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, and the occurrence of such dash marks, image unevenness, and image blur is increased. It was.

  On the other hand, recent electrophotographic image forming apparatuses tend to be used as information equipment for printing out image information produced by a computer, and there are copying machines and printers capable of forming high-quality digital images. It has been demanded. Therefore, there is a need for a developing means that faithfully visualizes the electrostatic latent image formed on the organic photoreceptor, and as one of the means, polymerized toner having a monodispersed particle size distribution is used as the developing means. (Patent Document 2). However, even if the toner capable of faithfully reproducing the electrostatic latent image is used, if the electrostatic latent image is formed on the organic photoreceptor whose surface is rough due to the generation of the dash mark, the image unevenness, and the image blur, as described above. Thus, there has been found a problem that the formation of the electrostatic latent image itself is disturbed, the roughness is reproduced as a clearer toner image, and the toner characteristics improved by the particle size distribution cannot be sufficiently exhibited.

In addition, if the surface layer of the organophotoreceptor contains fluorine-containing resin fine particles having an average particle size of more than 0.20 μm, it causes scattering of laser exposure light, deteriorates sharpness, deteriorates film properties, and increases mechanical strength. It tends to decrease and causes problems such as the occurrence of scratches on the surface of the photoreceptor, and a satisfactory electrophotographic image cannot always be provided.
JP-A-8-328287 JP 2002-244336 A

  The present invention solves the problems of the organic photoreceptor having a surface layer containing the above-mentioned fluororesin fine particles, and develops an organic photoreceptor having a surface layer having a uniform low surface energy. Forming an electrophotographic image using a toner whose distribution is close to monodisperse prevents the occurrence of dash marks, image unevenness due to black and white streaks, and image blurring and good sharpness. It is to provide a simple image forming apparatus, and to provide an image forming method using the image forming apparatus.

As a result of repeated studies on the above problems, the object of the present invention is to improve the dispersibility of the fluororesin fine particles having a low crystallinity and a reduced diameter, and to provide an organic photosensitive material having a surface layer having a uniform low surface energy. The present invention has been completed by finding that the electrostatic latent image formed on the organic photoreceptor can be visualized by using a developing means containing toner having a particle size distribution close to monodispersion. That is, the present invention is achieved by having the following configuration.
(Claim 1)
In an image forming apparatus having an organic photoreceptor and a charging means for forming an electrostatic latent image on the organic photoreceptor, an exposure means, and a developing means for developing the electrostatic latent image into a toner image. The organic photoreceptor contains fluorine-containing resin fine particles and a binder resin 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 a contact angle with water of 90 ° or more. And having a surface layer with a variation in contact angle of ± 2.0 °, where the developing means has a particle size of 0.7 × (Dp50) or less, where Dp50 is the 50% number particle size of the toner particles. An image forming apparatus comprising a toner in which the number of toner particles is 10% by number or less.
(Claim 2)
In an image forming apparatus having an organic photoreceptor and a charging means for forming an electrostatic latent image on the organic photoreceptor, an exposure means, and a developing means for developing the electrostatic latent image into a toner image. The organic photoreceptor contains fluorine-containing resin fine particles and a binder resin 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 a contact angle with water of 90 ° or more. And having a surface layer with a variation in contact angle of ± 2.0 °, and the developing means has a ratio (Dv50 / 50) of 50% volume particle size (Dv50) to 50% number particle size (Dp50) of toner particles. Dp50) is 1.0 to 1.15, and the ratio of the cumulative 75% volume particle size (Dv75) from the larger volume particle size to the cumulative 75% number particle size (Dp75) from the larger number particle size (Dv75 / Dp75) is 1.0 to 1.20, and An image forming apparatus comprising a toner having a particle diameter of 0.7 × (Dp50) or less and having a toner particle number of 10% by number or less.
(Claim 3)
The image forming apparatus according to claim 1, wherein at least one of the binder resins is a siloxane-modified polycarbonate.
(Claim 4)
The image forming apparatus according to claim 1, wherein the fluororesin fine particles coexist with an antioxidant.
(Claim 5)
The organic photoconductor has a charge generation layer and a plurality of charge transport layers on a conductive support, and the uppermost layer of the plurality of layers is a surface layer. The image forming apparatus described in the item.
(Claim 6)
In an image forming method in which an electrostatic latent image is formed on an organic photoreceptor, and the electrostatic latent image is visualized by a developing unit to form an electrophotographic image, the organic photoreceptor has an average primary particle size of 0.1. It contains fluorine-containing resin fine particles and a binder resin having a crystallinity of less than 90% and not less than 0.2 μm and less than 0.20 μm. A toner having a certain surface layer and the developing means has a toner particle number of not more than 10% by number of toner particles having a particle size of 0.7 × (Dp50) or less, where Dp50 is a 50% number particle size of toner particles. An image forming method comprising:
(Claim 7)
In an image forming method in which an electrostatic latent image is formed on an organic photoreceptor, and the electrostatic latent image is visualized by a developing unit to form an electrophotographic image, the organic photoreceptor has an average primary particle size of 0.1. It contains fluorine-containing resin fine particles and a binder resin having a crystallinity of less than 90% and not less than 0.2 μm and less than 0.20 μm. The developing means has a ratio (Dv50 / Dp50) of 50% volume particle size (Dv50) to 50% number particle size (Dp50) of toner particles of 1.0 to 1.15; The ratio (Dv75 / Dp75) of the cumulative 75% volume particle diameter (Dv75) from the larger volume particle diameter to the cumulative 75% number particle diameter (Dp75) from the larger number particle diameter is 1.0 to 1.20. Toner particles having a particle size of 0.7 × (Dp50) or less Image forming method characterized in that the number contains a toner is 10% by number or less.

  By using the image forming apparatus and the image forming method of the present invention, the dispersibility of the fluororesin fine particles in the surface layer can be made uniform, and dash marks, image unevenness, and image blur, which have been problems in the past, are improved. And an electrophotographic image with good sharpness can be formed.

  Hereinafter, the present invention will be described in detail.

  The image forming apparatus according to the present invention includes an organic photosensitive member, a charging unit for forming an electrostatic latent image on the organic photosensitive member, an exposure unit, and a development for developing the electrostatic latent image into a toner image. A fluororesin fine particle and a binder 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%. It has a surface layer that contains a resin, has a contact angle with water of 90 ° or more and a contact angle variation of ± 2.0 °, and the developing means has a 50% number particle size of toner particles as Dp50. And a toner having a particle diameter of 0.7 × (Dp50) or less and having a toner particle number of 10% by number or less.

  The image forming apparatus according to the present invention also provides a charging means for forming an electrostatic latent image on the organic photoreceptor, an exposure means, and a toner image to visualize the electrostatic latent image. Fluorine-containing resin 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 a binder resin, having a surface layer having a contact angle with respect to water of 90 ° or more and a variation in contact angle of ± 2.0 °, and the developing means has a 50% volume particle size (Dv50) of toner particles. ) And 50% number particle size (Dp50) (Dv50 / Dp50) is 1.0 to 1.15, and the cumulative 75% volume particle size (Dv75) and number particle size Ratio of 75% cumulative particle diameter (Dp75) from the larger one (Dv75 / Dp75) is 1.0 to 1.20, and the number of toner particles having a particle size of 0.7 × (Dp50) or less is 10% by number or less.

  Since the image forming apparatus of the present invention has the above-described structure, it is possible to prevent generation of dash marks, image unevenness, and image blur for a long period of time, and to form an electrophotographic image with good image quality.

  As described above, the fluororesin fine particles have poor dispersion uniformity, and it has been difficult to produce an organic photoreceptor having a uniform and smooth surface layer free from 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 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 forming a small surface layer, it is possible to produce an organic photoreceptor that can prevent the generation of dash marks, image unevenness, and image blur for a long time and can accurately form a fine dot latent image. it can.

  An organophotoreceptor having the above characteristics can be obtained by producing its surface layer as follows. That is, the surface layer dispersion is composed of a binder resin and a component containing 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%, and the dispersion is dispersed. Dispersion with a low-boiling solvent having good properties, preferably an organic solvent having a boiling point of 120 ° C. or lower under atmospheric pressure (for example, THF, ethanol, toluene, dichloroethane, etc.). A stable dispersion is produced by suppressing the cohesiveness of. 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. Can be formed.

  The coating liquid supply type coating apparatus refers to a coating apparatus that supplies and applies a coating liquid necessary for layer formation onto a conductive support. For example, a coating apparatus having a slide hopper type coating head (hereinafter, referred to as a coating apparatus). Also referred to as a slide hopper type coating apparatus), a coating apparatus having an extrusion type coating head, and a spray type coating apparatus. 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. In addition, since the slide hopper type coating apparatus can continuously supply the coating liquid, a uniform coating film with less variation in contact angle can be formed as compared with a spray type coating apparatus.

  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-shaped portion 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 slide surface end and the base material are arranged with a certain gap, so that the base material is not damaged, and even when layers having different properties are formed in multiple layers, it can be applied without damaging the already applied layer. .

  In the coating method using the circular slide hopper type coating device of the present invention, the slide surface end and the base material are arranged with a certain gap, so that the base material is not damaged, and layers having different properties are formed in multiple layers. Also, the coating can be performed 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. In addition, the frictional resistance with the contact member of the photosensitive member such as a cleaning blade is large, wear due to scratching increases, streaky image unevenness occurs, and sharpness is likely to deteriorate. 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. In addition, image unevenness and image blur 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 a general formula;

(In the formula, 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 trifluoro). Is a methyl 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 present invention uses the organic photoreceptor having the 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 structure of the photoreceptor of the present invention comprises 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 a peak of an X-ray diffraction pattern of less than 90%. The contact angle with respect to water is 90 ° or more, and is not particularly limited as long as the surface layer has a contact angle variation of ± 2.0 °, and examples thereof include the following configurations;
1) A structure in which a charge generation layer and a charge transport layer are sequentially laminated as a photosensitive layer on a conductive support. 2) A 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 structure of the photoreceptor of the present invention, an undercoat layer may be formed on the conductive support prior to the formation of the photosensitive layer.

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

  A specific configuration of the photoreceptor will be described below by taking as an example the layer configuration of 2) which is most preferably used in the present invention.

Conductive Support As the conductive support used in the photoreceptor of the present invention, a sheet-like or cylindrical conductive support is used.

  The cylindrical conductive support of the present invention means a cylindrical support necessary for forming an endless image by rotating, and the cylindricity is preferably 5 to 40 μm, more preferably 7 to 30 μm.

  This cylindricity is based on JIS standard (B0621-1984). That is, when the cylindrical substrate is sandwiched between two coaxial geometric cylinders, it is represented by the difference in radius at the position where the distance between the two coaxial cylinders is minimum. In the present invention, the difference in radius is represented by μm. The method of measuring the cylindricity is obtained by measuring the roundness of 7 points in total, that is, 2 points 10 mm on both ends of the cylindrical substrate, 4 points of the central part, and 4 points obtained by dividing the distance between the both ends. The measuring device can be measured using a non-contact universal roll diameter measuring machine (manufactured by Mitutoyo Corporation).

As a material for the conductive support, 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.

  As the conductive support used in the present invention, one having an alumite film that has been sealed on the surface thereof may be used. The alumite treatment is usually performed in an acidic bath such as chromic acid, sulfuric acid, oxalic acid, phosphoric acid, boric acid, sulfamic acid, etc., but anodizing treatment in sulfuric acid gives the most preferable result. In the case of anodizing in sulfuric acid, the sulfuric acid concentration is preferably 100 to 200 g / l, the aluminum ion concentration is 1 to 10 g / l, the liquid temperature is about 20 ° C., and the applied voltage is preferably about 20 V. It is not limited. The average film thickness of the anodized film is usually 20 μm or less, particularly preferably 10 μm or less.

Intermediate layer In the present invention, an intermediate layer having a barrier function may be provided between the conductive support and the photosensitive layer.

  In the present invention, in order to improve the adhesion between the conductive support and the photosensitive layer, or to prevent charge injection from the support, an intermediate layer (including an undercoat layer) is provided between the support and the photosensitive layer. Including) can also be provided. Examples of the material for the intermediate layer include polyamide resins, vinyl chloride resins, vinyl acetate resins, and copolymer resins containing two or more of these resin repeating units. Of these subbing resins, a polyamide resin is preferable as a resin capable of reducing the increase in residual potential due to repeated use. The film thickness of the intermediate layer using these resins is preferably 0.01 to 0.5 μm.

  Examples of the intermediate layer preferably used in the present invention include an intermediate layer using a curable metal resin obtained by thermosetting an organic metal compound such as a silane coupling agent or a titanium coupling agent. As for the film thickness of the intermediate | middle layer using curable metal resin, 0.1-2 micrometers is preferable.

  An intermediate layer preferably used in the present invention includes an intermediate layer in which inorganic particles are dispersed in a binder resin. The average particle diameter of the inorganic particles is preferably 0.01 to 1 μm. In particular, an intermediate layer in which N-type semiconductive fine particles subjected to surface treatment are dispersed in a binder is preferable. For example, an intermediate layer in which titanium oxide having an average particle size of 0.01 to 1 μm, which has been surface-treated with silica / alumina treatment and a silane compound, is dispersed in a polyamide resin. The film thickness of such an intermediate layer is preferably 1 to 20 μm.

  The N-type semiconducting fine particles are fine particles having the property of using conductive carriers as electrons. That is, the property that the conductive carrier is an electron is that the N-type semiconducting fine particles are contained in an insulating binder to effectively block hole injection from the substrate, and to convert electrons from the photosensitive layer into electrons. On the other hand, it has the property which does not show blocking property.

  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.

Specific examples of the N-type semiconducting fine particles include fine particles of titanium oxide (TiO ₂ ), zinc oxide (ZnO), tin oxide (SnO ₂ ), etc. In the present invention, titanium oxide is particularly preferably used. It is done.

  The average particle diameter of the N-type semiconducting fine particles used in the present invention is preferably in the range of 10 nm to 500 nm in the number average primary particle diameter, more preferably 10 nm to 200 nm, and particularly preferably 15 nm to 50 nm. .

  The intermediate layer using N-type semiconducting fine particles whose number average primary particle size is within the above range can be finely dispersed in the layer, has sufficient potential stability, and generates black spots. Has a prevention function.

  For example, in the case of titanium oxide, the number-average primary particle size of the N-type semiconducting fine particles is magnified 10,000 times by observation with a transmission electron microscope, and 100 particles are randomly observed as primary particles. It is measured as the number average diameter.

  The shape of the N-type semiconducting fine particles used in the present invention includes dendritic, needle-like, and granular shapes. For example, in the case of titanium oxide particles, the N-type semiconductive fine particles have a crystalline form. There are anatase type, rutile type and amorphous type, but any crystal type may be used, or two or more crystal types may be mixed and used. Of these, the rutile type is the best.

  One of the hydrophobizing surface treatments performed on the N-type semiconducting fine particles is a plurality of surface treatments, and the last surface treatment is a surface treatment with a reactive organosilicon compound. Is to do. In addition, at least one of the surface treatments is at least one surface treatment selected from alumina, silica, and zirconia, and finally the surface treatment of the reactive organosilicon compound is performed. It is preferable.

  Alumina treatment, silica treatment, and zirconia treatment are treatments for depositing alumina, silica, or zirconia on the surface of the N-type semiconducting fine particles. Alumina, silica, and zirconia deposited on these surfaces include alumina, silica, Zirconia hydrates are also included. The surface treatment of the reactive organosilicon compound means using a reactive organosilicon compound in the treatment liquid.

  In this way, the surface treatment of the N-type semiconductive fine particles such as titanium oxide particles was performed at least twice, so that the surface of the N-type semiconductive fine particles was uniformly coated (treated), and the surface treatment was performed. When N-type semiconducting fine particles are used in the intermediate layer, a good photoconductor having good dispersibility of N-type semiconductive fine particles such as titanium oxide particles in the intermediate layer and causing no image defects such as black spots. You can get it.

Photosensitive layer Charge generation layer In the organic photoreceptor of the present invention, the above-mentioned titanyl phthalocyanine adduct pigment is used as a charge generation material, but other phthalocyanine pigments, azo pigments, perylene pigments, azurenium pigments, etc. may be used in combination. Can do.

  When a binder is used as the CGM dispersion medium in the charge generation layer, a known resin can be used as the binder, but the most preferred resins include formal resin, butyral resin, silicone resin, silicone-modified butyral resin, phenoxy resin, and the like. Can be mentioned. The ratio of the binder resin to the charge generating material is preferably 20 to 600 parts by mass with respect to 100 parts by mass of the binder resin. By using these resins, the increase in residual potential associated with repeated use can be minimized. The thickness of the charge generation layer is preferably 0.3 μm to 2 μm.

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

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

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

  The surface layer containing the fluororesin fine particles of the present invention preferably contains an antioxidant. The surface layer containing the fluorine-containing resin fine particles is easily oxidized by an active gas such as NOx or ozone during charging of the photoconductor, and image blurring is likely to occur. However, the presence of an antioxidant causes image blurring. Can be prevented. Typical examples of the antioxidants are those that prevent the action of oxygen under conditions of light, heat, discharge, etc. on auto-oxidizing substances present in the organic photoreceptor or on the surface of the organic photoreceptor, It is a substance that has the property of inhibiting. Typical examples include the following compound groups.

  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.

  In addition, the present invention employs an image forming apparatus that uses both the organic photoreceptor and a developing means using a toner having a sharp particle size distribution as described below, thereby preventing image unevenness and image blur due to dash marks or scratches. Generation | occurrence | production can be prevented and a favorable electrophotographic image can be produced.

  The toner of the present invention is characterized by containing a toner having a particle diameter of 0.7 × (Dp50) or less and a toner particle number of 10% or less, where the toner particle diameter is 50%. .

  In the toner of the present invention, the ratio (Dv50 / Dp50) of 50% volume particle size (Dv50) to 50% number particle size (Dp50) of toner particles is 1.0 to 1.15, The ratio (Dv75 / Dp75) of the cumulative 75% volume particle size (Dv75) from the larger one to the cumulative 75% number particle size (Dp75) from the larger number particle size is 1.0 to 1.20, and It is characterized by containing a toner having a particle diameter of 0.7 × (Dp50) or less and the number of toner particles being 10% or less.

  That is, in the present invention, by using together the above-described photoreceptor of the present invention and the developing means containing the toner having the particle size distribution as described above, it is possible to simultaneously improve the occurrence of image unevenness and image blur due to dashes and scratches. And an image forming apparatus capable of producing a good electrophotographic image.

  That is, the toner used in the present invention is preferably monodispersed or close to the particle size distribution. In particular, the toner having a smaller particle size than the average particle size distribution is used as a developer component. When the photoreceptor of the present invention is used, it is possible to provide an image forming apparatus capable of simultaneously improving the occurrence of image unevenness and image blur due to dash marks and scratches and producing a good electrophotographic image.

If a toner particle having a particle diameter of 0.7 × (Dp50) or less is larger than 10% by weight, assuming that the 50% number particle diameter of the toner particles is Dp50, for example, even if the photoreceptor of the present invention is used, This may cause an increase in weakly charged components, generation of reverse polarity toner, or generation of overcharged components. As a result, fogging occurs, image unevenness and image blur occur, and the sharpness of the character image tends to deteriorate.

  The toner of the present invention includes a toner particle having a 50% volume particle size (Dv50) and a 50% number of particles in addition to the condition that the number of toner particles of 0.7 × (Dp50) or less is 10% by number or less. The ratio (Dv50 / Dp50) of the diameter (Dp50) is 1.0 to 1.15, the cumulative 75% volume particle diameter (Dv75) from the larger volume particle diameter and the accumulated 75 from the larger number particle diameter. It is more preferable that the ratio (Dv75 / Dp75) of the% number particle size (Dp75) is 1.0 to 1.20.

  The 50% volume average particle diameter (Dv50) is preferably 3.0 to 9.5 μm, more preferably 3.0 to 7.5 μm. By setting this range, the resolution can be increased.

  In the present invention, the cumulative 75% volume particle size (Dv75) or cumulative 75% number particle size (Dp75) from the larger one is the cumulative frequency from the larger particle size, the sum of the total volume or the sum of the numbers. On the other hand, each is represented by a volume particle size or a number particle size of a particle size distribution portion showing 75%.

  In the present invention, 50% volume particle size (Dv50), 50% number particle size (Dp50), cumulative 75% volume particle size (Dv75), cumulative 75% number particle size (Dp75), etc. It can be measured with Multisizer (Coulter).

  Further, as the toner of the present invention, 10% by number of toner particles having a particle size of 0.7 × (Dp50) or less is used. The amount of fine powder toner is an electrophoretic light scattering photometer ELS-800 manufactured by Otsuka Electronics Co., Ltd. Can be measured.

  In the technical field where the electrostatic latent image to which the present invention belongs is visualized by dry development, toner obtained by adding an external additive or the like to at least colored particles (prototype of toner particles) composed of a colorant and a resin is used. It is used as. However, as long as there is no particular problem, the colored particles and the toner are generally described without distinction. In the particle size and particle size distribution in the present invention, there is no change in the measured value when either colored particles or toner particles are measured.

  Further, the diameter of external additives and the like is on the order of nm (number average primary particles), and can be measured with a light scattering electrophoresis particle size measuring device “ELS-800” (manufactured by Otsuka Electronics Co., Ltd.).

  Hereinafter, the configuration and production method of the toner used in the present invention showing the above-described particle size distribution will be described in detail.

<toner>
The toner used in the present invention may be a pulverized toner or a polymerized toner, as long as it is a toner prepared in the above range of the present invention. However, the toner of the present invention is a polymerization method from the viewpoint of obtaining a stable particle size distribution. Polymerized toners that can be produced by

  The term “polymerized toner” means a toner in which a toner binder resin is formed and a toner shape is formed by polymerization of a raw material monomer of the binder resin and, if necessary, subsequent chemical treatment. More specifically, it means a toner formed through a polymerization reaction such as suspension polymerization or emulsion polymerization, and if necessary, a step of fusing particles between them.

  In the present invention, it is preferable to use associative toner obtained by salting out / fusing resin particles containing a release agent and colorant particles as toner.

  This is because, in addition to being able to produce a toner having the particle size distribution as described above, the associative toner has a uniform surface property between the toner particles, and the effects of the present invention can be achieved without impairing the transferability. It is estimated that he was able to demonstrate.

  The above-mentioned “salting out / fusion” means that salting out (aggregation of particles) and fusion (disappearance of the interface between particles) occur at the same time, or act of causing salting out and fusion at the same time. . In order to perform salting-out and fusion at the same time, it is necessary to agglomerate particles (resin particles, colorant particles) under a temperature condition equal to or higher than the glass transition temperature (Tg) of the resin constituting the resin particles.

<Release agent>
The release agent constituting the toner of the present invention is not particularly limited, but comprises a crystalline ester compound (hereinafter referred to as “specific ester compound”) represented by the following general formula (2). It is preferable.

Formula _{(2): R 1 - (} OCO-R 2) n
(In the formula, each of R ₁ and R ₂ represents a hydrocarbon group having 1 to 40 carbon atoms which may have a substituent, and n is an integer of 1 to 4).
<Specific ester compounds>
In General formula (2) which shows a specific ester compound, R < ₁ > and R < ₂ > show the hydrocarbon group which may have a substituent, respectively.

The hydrocarbon group R ₁ has 1 to 40 carbon atoms, preferably 1 to 20 carbon atoms, more preferably 2 to 5 carbon atoms.

The hydrocarbon group R ₂ has 1 to 40 carbon atoms, preferably 16 to 30 carbon atoms, more preferably 18 to 26 carbon atoms.

  In the general formula (2), n is an integer of 1 to 4, preferably 2 to 4, more preferably 3 to 4, and particularly preferably 4.

  The specific ester compound can be suitably synthesized by a dehydration condensation reaction between an alcohol and a carboxylic acid.

  The most preferred specific ester compound may include pentaerythritol tetrabehenate.

  Specific examples of the specific ester compound include compounds represented by the following formulas 1) to 26).

<Ratio of release agent>
The content of the release agent in the toner of the present invention is usually 1 to 30% by mass, preferably 2 to 20% by mass, and more preferably 3 to 15% by mass.

<Resin particles containing release agent>
In the present invention, “resin particles containing a release agent” means that a release agent is dissolved in a monomer for obtaining a binder resin, and the resulting monomer solution is dispersed in an aqueous medium. Can be obtained as latex particles.

  The resin particles preferably have a weight average particle diameter of 50 to 2000 nm.

  Examples of the polymerization method for obtaining resin particles containing a release agent in the binder resin include granulation polymerization methods such as an emulsion polymerization method, a suspension polymerization method, and a seed polymerization method.

  As a preferable polymerization method for obtaining resin particles containing a release agent, a release agent is dissolved in a monomer in an aqueous medium in which a surfactant having a concentration equal to or lower than the critical micelle concentration is dissolved. A monomer solution is dispersed in oil droplets using mechanical energy to prepare a dispersion, and a water-soluble polymerization initiator is added to the resulting dispersion to perform radical polymerization (hereinafter referred to as this specification). (Referred to as “mini-emulsion method”). Instead of adding a water-soluble polymerization initiator, or while adding the water-soluble polymerization initiator, an oil-soluble polymerization initiator may be added to the monomer solution.

  Here, a dispersing machine for dispersing oil droplets by mechanical energy is not particularly limited. For example, a stirring device “CLEARMIX” (M-Technique) equipped with a rotor that rotates at high speed is used. (Manufactured by Co., Ltd.), ultrasonic disperser, mechanical homogenizer, manton gorin, pressure homogenizer, and the like. The dispersed particle diameter is 10 to 1000 nm, preferably 30 to 300 nm.

<Binder resin>
The binder resin constituting the toner of the present invention comprises a high molecular weight component having a peak or shoulder in the region of 100,000 to 1,000,000 in the molecular weight distribution measured by GPC, and 1,000 to 20,000. A resin containing a low molecular weight component having a peak or shoulder in the region is preferable.

  Here, as a method for measuring the molecular weight of the resin by GPC, 1 ml of THF is added to 0.5 to 5.0 mg (specifically 1 mg) of a measurement sample, and stirring is performed at room temperature using a magnetic stirrer or the like. Go and dissolve well. Subsequently, after processing with a membrane filter having a pore size of 0.45 to 0.50 μm, the solution is injected into GPC.

  As GPC measurement conditions, the column is stabilized at 40 ° C., THF is allowed to flow at a flow rate of 1 ml per minute, and about 100 μl of a sample having a concentration of 1 mg / ml is injected for measurement. The column is preferably used in combination with a commercially available polystyrene gel column. For example, combinations of Shodex GPC KF-801, 802, 803, 804, 805, 806, and 807 manufactured by Showa Denko KK, and TSKgel G1000H, G2000H, G3000H, G4000H, G5000H, G6000H, G7000H, TSK guard column manufactured by Tosoh Corporation Combinations can be mentioned. As a detector, a refractive index detector (IR detector) or a UV detector may be used. In the measurement of the molecular weight of a sample, the molecular weight distribution of the sample is calculated using a calibration curve prepared using monodisperse polystyrene standard particles. About 10 points may be used as polystyrene for preparing a calibration curve.

Hereinafter, the constituent material of resin particles and the preparation method (polymerization method) will be described.
(Monomer)
As a polymerizable monomer used for obtaining resin particles, a radical polymerizable monomer is an essential constituent component, and a crosslinking agent can be used as necessary. Moreover, it is preferable to contain at least one radical polymerizable monomer having the following acidic group or radical polymerizable monomer having a basic group.
(1) Radical polymerizable monomer:
The radical polymerizable monomer is not particularly limited, and a conventionally known radical polymerizable monomer can be used. Moreover, it can be used combining 1 type (s) or 2 or more types so that the required characteristic may be satisfy | filled.

  Specifically, aromatic vinyl monomers, (meth) acrylic acid ester monomers, vinyl ester monomers, vinyl ether monomers, monoolefin monomers, diolefin monomers , Halogenated olefin monomers and the like can be used.

  Examples of the aromatic vinyl monomer include styrene, o-methyl styrene, m-methyl styrene, p-methyl styrene, p-methoxy styrene, p-phenyl styrene, p-chloro styrene, p-ethyl styrene, p. -N-butyl styrene, p-tert-butyl styrene, pn-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene, 2, Examples thereof include styrene monomers such as 4-dimethylstyrene and 3,4-dichlorostyrene and derivatives thereof.

  Examples of (meth) acrylic acid ester monomers include methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, and methacrylic acid. Examples include butyl, hexyl methacrylate, 2-ethylhexyl methacrylate, ethyl β-hydroxyacrylate, propyl γ-aminoacrylate, stearyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, and the like.

  Examples of vinyl ester monomers include vinyl acetate, vinyl propionate, and vinyl benzoate.

  Examples of the vinyl ether monomer include vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether, vinyl phenyl ether and the like.

  Examples of the monoolefin monomer include ethylene, propylene, isobutylene, 1-butene, 1-pentene, 4-methyl-1-pentene and the like.

  Examples of the diolefin monomer include butadiene, isoprene, chloroprene and the like.

  Examples of the halogenated olefin monomer include vinyl chloride, vinylidene chloride, vinyl bromide and the like.

(2) Crosslinking agent:
As the crosslinking agent, a radical polymerizable crosslinking agent may be added in order to improve the properties of the toner. Examples of the radically polymerizable crosslinking agent include those having two or more unsaturated bonds such as divinylbenzene, divinylnaphthalene, divinyl ether, diethylene glycol methacrylate, ethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, and diallyl phthalate.

(3) Radical polymerizable monomer having an acidic group or a basic group:
Examples of the radical polymerizable monomer having an acidic group or the radical polymerizable monomer having a basic group include a carboxyl group-containing monomer, a sulfonic acid group-containing monomer, a primary amine, and a secondary group. Amine-based compounds such as amines, tertiary amines, and quaternary ammonium salts can be used.

  Examples of the radical polymerizable monomer having an acidic group include carboxylic acid group-containing monomers such as acrylic acid, methacrylic acid, fumaric acid, maleic acid, itaconic acid, cinnamic acid, maleic acid monobutyl ester, and maleic acid monoester. An octyl ester etc. are mentioned.

  Examples of the sulfonic acid group-containing monomer include styrene sulfonic acid, allyl sulfosuccinic acid, octyl allyl sulfosuccinate and the like.

  These may have a structure of an alkali metal salt such as sodium or potassium or an alkaline earth metal salt such as calcium.

  Examples of the radical polymerizable monomer having a basic group include amine compounds, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl acrylate, diethylaminoethyl methacrylate, and quaternary ammonium salts of the above four compounds, 3-dimethylaminophenyl acrylate, 2-hydroxy-3-methacryloxypropyltrimethylammonium salt, acrylamide, N-butylacrylamide, N, N-dibutylacrylamide, piperidylacrylamide, methacrylamide, N-butylmethacrylamide, N-octadecylacrylamide Vinyl pyridine, vinyl pyrrolidone; vinyl N-methylpyridinium chloride, vinyl N-ethylpyridinium chloride, N, N-diary Ammonium chloride, N, N-diallyl-ethyl ammonium chloride, and the like.

  As the radical polymerizable monomer used in the present invention, a radical polymerizable monomer having an acidic group or a radical polymerizable monomer having a basic group is used in an amount of 0.1 to 15% by mass based on the whole monomer. The radical polymerizable crosslinking agent is preferably used in the range of 0.1 to 10% by mass with respect to the total radical polymerizable monomer, although it depends on its properties.

[Chain transfer agent]
For the purpose of adjusting the molecular weight of the resin particles, it is possible to use a commonly used chain transfer agent.

  The chain transfer agent is not particularly limited, for example, mercaptans such as octyl mercaptan, dodecyl mercaptan, tert-dodecyl mercaptan, mercaptopropionates such as n-octyl-3-mercaptopropionate, carbon tetrabromide, etc. And styrene dimer etc. are used.

(Polymerization initiator)
The radical polymerization initiator used in the present invention can be appropriately used as long as it is water-soluble. For example, persulfates (potassium persulfate, ammonium persulfate, etc.), azo compounds (4,4′-azobis-4-cyanovaleric acid and its salts, 2,2′-azobis (2-amidinopropane) salts, etc.), peroxides Compounds and the like.

  Furthermore, the radical polymerization initiator can be combined with a reducing agent as necessary to form a redox initiator. By using a redox initiator, the polymerization activity is increased, the polymerization temperature is lowered, and the polymerization time can be further shortened.

  The polymerization temperature may be any temperature as long as it is equal to or higher than the lowest radical generation temperature of the polymerization initiator, but for example, a range of 50 ° C. to 90 ° C. is used. However, it is possible to perform polymerization at room temperature or higher by using a polymerization initiator that starts at room temperature, for example, a combination of hydrogen peroxide and a reducing agent (ascorbic acid or the like).

[Surfactant]
In order to perform polymerization using the above-mentioned radical polymerizable monomer, it is necessary to perform oil droplet dispersion in an aqueous medium using a surfactant. Although it does not specifically limit as surfactant which can be used in this case, The following ionic surfactant can be mentioned as an example of a suitable thing.

  Examples of ionic surfactants include sulfonates (sodium dodecylbenzenesulfonate, sodium arylalkylpolyethersulfonate, 3,3-disulfonediphenylurea-4,4-diazo-bis-amino-8-naphthol-6 Sodium sulfonate, ortho-carboxybenzene-azo-dimethylaniline, 2,2,5,5-tetramethyl-triphenylmethane-4,4-diazo-bis-β-naphthol-6-sodium sulfonate, etc.), sulfuric acid Ester salts (sodium dodecyl sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, etc.), fatty acid salts (sodium oleate, sodium laurate, sodium caprate, sodium caprylate, sodium caproate, potassium stearate) Beam, calcium oleate and the like).

  Nonionic surfactants can also be used. Specifically, polyethylene oxide, polypropylene oxide, a combination of polypropylene oxide and polyethylene oxide, ester of polyethylene glycol and higher fatty acid, alkylphenol polyethylene oxide, ester of higher fatty acid and polyethylene glycol, ester of higher fatty acid and polypropylene oxide, sorbitan ester Etc.

<Colorant>
Examples of the colorant constituting the toner of the present invention include inorganic pigments, organic pigments, and dyes.

  A conventionally well-known thing can be used as an inorganic pigment. Specific inorganic pigments are exemplified below.

  Examples of the black pigment include carbon black such as furnace black, channel black, acetylene black, thermal black, and lamp black, and magnetic powder such as magnetite and ferrite.

  These inorganic pigments can be used alone or in combination as required. Moreover, the addition amount of a pigment is 2-20 mass% with respect to a polymer, Preferably 3-15 mass% is selected.

  When used as a magnetic toner, the above-mentioned magnetite can be added. In this case, it is preferable to add 20 to 60% by mass in the toner from the viewpoint of imparting predetermined magnetic properties.

  Conventionally known organic pigments and dyes can also be used. Specific organic pigments and dyes are exemplified below.

  Examples of pigments for magenta or red include C.I. I. Pigment red 2, C.I. I. Pigment red 3, C.I. I. Pigment red 5, C.I. I. Pigment red 6, C.I. I. Pigment red 7, C.I. I. Pigment red 15, C.I. I. Pigment red 16, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 53: 1, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 123, C.I. I. Pigment red 139, C.I. I. Pigment red 144, C.I. I. Pigment red 149, C.I. I. Pigment red 166, C.I. I. Pigment red 177, C.I. I. Pigment red 178, C.I. I. And CI Pigment Red 222.

  Examples of the orange or yellow pigment include C.I. I. Pigment orange 31, C.I. I. Pigment orange 43, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 13, C.I. I. Pigment yellow 14, C.I. I. Pigment yellow 15, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 94, C.I. I. Pigment yellow 138, C.I. I. Pigment yellow 180, C.I. I. Pigment yellow 185, C.I. I. Pigment yellow 155, C.I. I. And CI Pigment Yellow 156.

  Examples of pigments for green or cyan include C.I. I. Pigment blue 15, C.I. I. Pigment blue 15: 2, C.I. I. Pigment blue 15: 3, C.I. I. Pigment blue 16, C.I. I. Pigment blue 60, C.I. I. And CI Pigment Green 7.

  As the dye, C.I. I. Solvent Red 1, 49, 52, 58, 63, 111, 122, C.I. I. Solvent Yellow 19, 44, 77, 79, 81, 82, 93, 98, 103, 104, 112, 162, C.I. I. Solvent Blue 25, 36, 60, 70, 93, 95 etc. can be used, and a mixture thereof can also be used.

  These organic pigments and dyes can be used alone or in combination as desired. Moreover, the addition amount of a pigment is 2-20 mass% with respect to a polymer, Preferably 3-15 mass% is selected.

  The colorant can also be used after surface modification. As the surface modifier, conventionally known ones can be used, and specifically, silane coupling agents, titanium coupling agents, aluminum coupling agents and the like can be preferably used.

<External additive>
To the toner of the present invention, so-called external additives can be added and used for the purpose of improving fluidity, chargeability and cleaning property. These external additives are not particularly limited, and various inorganic fine particles, organic fine particles and lubricants can be used.

  A conventionally well-known thing can be used as an inorganic fine particle. Specifically, silica, titanium, alumina fine particles and the like can be preferably used. These inorganic fine particles are preferably hydrophobic. Specifically, as silica fine particles, for example, commercially available products R805, R976, R974, R972, R812, R809 manufactured by Nippon Aerosil Co., Ltd. MS5 and the like.

  Examples of the titanium fine particles include commercial products T-805 and T-604 manufactured by Nippon Aerosil Co., Ltd., commercial products MT-100S, MT-100B, MT-500BS, MT-600, MT-600SS, and JA- 1. Commercial products TA-300SI, TA-500, TAF-130, TAF-510, TAF-510T manufactured by Fuji Titanium Co., Ltd. Commercial products IT-S, IT-OA, IT-OB, IT- manufactured by Idemitsu Kosan Co., Ltd. OC etc. are mentioned.

  Examples of the alumina fine particles include commercial products RFY-C and C-604 manufactured by Nippon Aerosil Co., Ltd. and commercial products TTO-55 manufactured by Ishihara Sangyo Co., Ltd.

  As the organic fine particles, spherical organic fine particles having a number average primary particle diameter of about 10 to 2000 nm can be used. As this, a homopolymer such as styrene or methyl methacrylate or a copolymer thereof can be used.

  Lubricants include, for example, zinc stearate, aluminum, copper, magnesium, calcium, etc., oleic acid zinc, manganese, iron, copper, magnesium, etc., palmitic acid zinc, copper, magnesium, calcium, etc. And salts of higher fatty acids such as zinc of linoleic acid, salts of calcium, etc., zinc of ricinoleic acid, salts of calcium, etc.

  The amount of these external additives added is preferably 0.1 to 5% by mass with respect to the toner.

  The toner of the present invention is preferably an associative toner obtained by salting out / fusing resin particles containing a release agent and colorant particles in an aqueous medium. Thus, by salting out / fusing the resin particles containing the release agent, a toner in which the release agent is finely dispersed can be obtained, and in addition to the effect of the particle size distribution, the chargeability can be obtained. It is possible to exhibit effects such as stabilization.

  The toner of the present invention has an irregular shape on the surface from the time of manufacture, and is an associative toner obtained by fusing resin particles and colorant particles in an aqueous medium. Therefore, the difference in shape and surface property between toner particles is extremely small, and as a result, the surface property tends to be uniform. For this reason, a difference in transferability and chargeability between toners hardly occurs, and an image can be kept good.

<Toner manufacturing process>
As an example of a method for producing the toner of the present invention,
(1) a dissolution step of preparing a monomer solution by dissolving a release agent in the monomer;
(2) A dispersion step of dispersing the obtained monomer solution in an aqueous medium,
(3) a polymerization step of preparing a dispersion (latex) of resin particles containing a release agent by polymerizing an aqueous dispersion of the resulting monomer solution;
(4) a salting-out / fusing step in which the resulting resin particles and the colorant particles are salted out / fused in an aqueous medium to obtain associated particles (toner particles);
(5) A filtration / washing step of separating the obtained associated particles from an aqueous medium and washing away the surfactant from the associated particles;
(6) Consists of a drying step of the washed associated particles,
(7) An external additive addition step of adding an external additive to the dried association particles may be included.

[Dissolution process]
The method for dissolving the release agent in the monomer is not particularly limited.

  The amount of the release agent dissolved in the monomer is such that the content of the release agent in the finally obtained toner is 1 to 30% by mass, preferably 2 to 20% by mass, more preferably 3 to 15% by mass. It is made an amount.

  An oil-soluble polymerization initiator and other oil-soluble components can also be added to the monomer solution.

[Dispersing process]
The method of dispersing the monomer solution in the aqueous medium is not particularly limited, but a method of dispersing by mechanical energy is preferable, and in particular, a surfactant having a concentration equal to or lower than the critical micelle concentration is dissolved. It is preferable to disperse oil droplets of the monomer solution in the aqueous medium to be obtained (essential aspect in the miniemulsion method).

  Here, the disperser for dispersing oil droplets by mechanical energy is not particularly limited. For example, “CLEARMIX”, ultrasonic disperser, mechanical homogenizer, Manton Gorin and pressure homogenizer, etc. Can be mentioned. The dispersed particle diameter is 10 to 1000 nm, preferably 30 to 300 nm.

[Polymerization process]
In the polymerization step, a conventionally known polymerization method (granulation polymerization method such as emulsion polymerization method, suspension polymerization method, seed polymerization method, etc.) can be basically employed.

  An example of a preferred polymerization method is a mini-emulsion method, that is, a monomer solution is dispersed in oil droplets using mechanical energy in an aqueous medium in which a surfactant having a critical micelle concentration or less is dissolved. Examples of the method include radical polymerization by adding a water-soluble polymerization initiator to the resulting dispersion.

[Salting out / fusion process]
In the salting-out / fusion step, a dispersion of colorant particles is added to the dispersion of resin particles obtained by the polymerization step, and the resin particles and the colorant particles are salted out in an aqueous medium. Fuse.

  In the salting-out / fusion step, internal additive particles such as a charge control agent can be fused together with the resin particles and the colorant particles.

  The “aqueous medium” in the salting out / fusion step refers to a material in which the main component (50% by mass or more) is water. Examples of components other than water include organic solvents that dissolve in water, such as methanol, ethanol, isopropanol, butanol, acetone, methyl ethyl ketone, and tetrahydrofuran. Among these, alcohol-based organic solvents such as methanol, ethanol, isopropanol, and butanol, which are organic solvents that do not dissolve the resin, are particularly preferable.

  The colorant particles used in the salting out / fusion process can be prepared by dispersing the colorant in an aqueous medium. The dispersion treatment of the colorant is performed in a state where the surfactant concentration is set to a critical micelle concentration (CMC) or more in water.

  The disperser used for the dispersion treatment of the colorant is not particularly limited, but preferably "CLEAMIX", an ultrasonic disperser, a mechanical homogenizer, a pressure disperser such as a manton gourin or a pressure homogenizer, a sand grinder, a Getzmann mill, Examples thereof include a medium type dispersing machine such as a diamond fine mill. Moreover, as a surfactant used, the same thing as the above-mentioned surfactant can be mentioned.

  The colorant (particles) may be surface-modified. In the surface modification method of the colorant, the colorant is dispersed in a solvent, the surface modifier is added to the dispersion, and the system is reacted by raising the temperature. After completion of the reaction, the colorant is separated by filtration, washed and filtered with the same solvent, and dried to obtain a colorant (pigment) treated with the surface modifier.

  In the salting-out / fusion method, a salting-out agent composed of an alkali metal salt and / or an alkaline earth metal salt or the like is added as a flocculant having a critical coagulation concentration or higher in water containing resin particles and colorant particles. Next, it is a step of performing fusion at the same time as salting-out proceeds by heating to the glass transition point or more of the resin particles. In this step, an organic solvent that is infinitely soluble in water may be added.

  Here, the alkali metal salt and alkaline earth metal salt which are salting-out agents include lithium, potassium, sodium and the like as the alkali metal, and examples of the alkaline earth metal include magnesium, calcium, strontium and barium. Preferably, potassium, sodium, magnesium, calcium, and barium are used. Examples of the salt include chlorine salt, bromine salt, iodine salt, carbonate salt, sulfate salt and the like.

  Furthermore, examples of the organic solvent infinitely soluble in water include methanol, ethanol, 1-propanol, 2-propanol, ethylene glycol, glycerin, acetone, etc., but methanol, ethanol, 1-propanol having 3 or less carbon atoms. 2-propanol is preferable, and 2-propanol is particularly preferable.

  In the salting-out / fusion process, it is preferable to shorten the time (time until heating is started) after adding the salting-out agent as short as possible. That is, after adding the salting-out agent, it is preferable to start heating the dispersion of the resin particles and the colorant particles as quickly as possible so that the temperature is equal to or higher than the glass transition temperature of the resin particles.

  The reason for this is not clear, but the agglomeration state of the particles fluctuates depending on the standing time after salting out, the particle size distribution becomes unstable, and the surface property of the fused toner fluctuates. Will occur.

  The time (starting time) until the heating is started is usually within 30 minutes, preferably within 10 minutes.

  Although the temperature which adds a salting-out agent is not specifically limited, It is preferable that it is below the glass transition temperature of a resin particle.

  Further, in the salting out / fusion process, it is necessary to quickly raise the temperature by heating, and the temperature raising rate is preferably 1 ° C./min or more. The upper limit of the heating rate is not particularly limited, but is preferably 15 ° C./min or less from the viewpoint of suppressing the generation of coarse particles due to rapid salting out / fusion.

  Furthermore, after the dispersion of resin particles and colorant particles reaches a temperature equal to or higher than the glass transition temperature, it is important to keep salting out / fusion by maintaining the temperature of the dispersion for a certain period of time. . As a result, toner particle growth (aggregation of resin particles and colorant particles) and fusion (disappearance at the interface between particles) can be effectively advanced, and the durability of the finally obtained toner is improved. can do.

  Further, after the growth of the associated particles is stopped, the fusion by heating may be continued.

[Filtering and washing process]
In this filtration / washing step, a filtration treatment for filtering the toner particles from the dispersion of toner particles obtained in the above step, and a surfactant or salt from the filtered toner particles (cake-like aggregate). A cleaning process for removing deposits such as a depositing agent is performed.

  Here, the filtration method is not particularly limited, such as a centrifugal separation method, a vacuum filtration method using Nutsche or the like, a filtration method using a filter press or the like.

[Drying process]
This step is a step of drying the washed toner particles.

  Examples of dryers used in this process include spray dryers, vacuum freeze dryers, vacuum dryers, etc., stationary shelf dryers, mobile shelf dryers, fluidized bed dryers, rotary dryers It is preferable to use a stirring dryer or the like.

  The water content of the dried toner particles is preferably 5% by mass or less, and more preferably 2% by mass or less.

  In addition, when the toner particles that have been dried are aggregated due to weak interparticle attraction, the aggregate may be crushed. Here, as the crushing treatment apparatus, a mechanical crushing apparatus such as a jet mill, a Henschel mixer, a coffee mill, or a food processor can be used.

[External additive addition process]
This step is a step of adding an external additive to the dried toner particles.

  Examples of the apparatus used for adding the external additive include various known mixing apparatuses such as a Turbuler mixer, a Henschel mixer, a Nauter mixer, and a V-type mixer.

  Further, in the toner of the present invention, the toner having a particle diameter of 0.7 × (Dp50) or less is 10% by number or less. In order to adjust the particle size distribution within this range, it is preferable to narrow the temperature control at the salting-out / fusion stage. Specifically, the temperature is raised as quickly as possible, that is, the temperature is raised faster. As this condition, it is shown in the above-mentioned conditions. The time until the temperature rises is less than 30 minutes, preferably less than 10 minutes, and the temperature rise rate is preferably 1 to 15 ° C./min.

  The toner of the present invention may contain materials capable of imparting various functions as toner materials in addition to the colorant and the release agent. Specific examples include charge control agents. These components can be added simultaneously with the resin particles and the colorant particles in the salting out / fusion step described above, and can be added by various methods such as a method included in the toner and a method of adding to the resin particles themselves.

  Similarly, various known charge control agents and those that can be dispersed in water can be used. Specific examples include nigrosine dyes, naphthenic acid or higher fatty acid metal salts, alkoxylated amines, quaternary ammonium salt compounds, azo metal complexes, salicylic acid metal salts or metal complexes thereof.

<Developer>
The toner of the present invention may be used as a one-component developer or a two-component developer.

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

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

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

  The carrier is preferably a carrier in which magnetic particles are further coated with a resin, or a so-called resin dispersion type carrier in which magnetic particles are dispersed in a resin. The resin composition for coating is not particularly limited, and for example, olefin resin, styrene resin, styrene-acrylic resin, silicone resin, ester resin, or fluorine-containing polymer resin is used. In addition, the resin for constituting the resin-dispersed carrier is not particularly limited, and a known resin can be used. For example, a styrene-acrylic resin, a polyester resin, a fluorine resin, a phenol resin, or the like is used. be able to.

  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, it is preferable to use a polymerized toner as a developer used in the developing means. 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.

  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. In the following text, “part” means “part by mass”.

Production of Photoreceptor 1 Photoreceptor 1 was produced as follows.

The surface of the cylindrical aluminum support was cut to prepare a conductive support having a ten-point surface roughness Rz = 1.5 (μm).
<Intermediate layer>
The following intermediate layer dispersion was diluted twice with the same mixed solvent, and allowed to stand overnight, followed by filtration (filter; rigesh mesh 5 μm filter manufactured by Nihon Pall) to prepare an intermediate layer coating solution.

Polyamide resin CM8000 (manufactured by Toray Industries, Inc.) 1 part Inorganic particles: Titanium oxide (Number average primary particle size 35 nm: Titanium oxide treated with silica / alumina and methylhydrogenpolysiloxane) 3 parts Methanol 10 parts are mixed as a disperser Using a sand mill, batch dispersion was performed for 10 hours to prepare an intermediate layer dispersion.

  It apply | coated so that it might become a dry film thickness of 1.0 micrometer on the said support body using the said coating liquid.

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

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

<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)>
815 parts of PTFE particle dispersion (4,4′-dimethyl-4 ″-(α-phenylstyryl)
Triphenylamine) 150 parts Siloxane-modified polycarbonate resin (PC-1) 150 parts Polycarbonate (Z300: manufactured by Mitsubishi Gas Chemical Company) 150 parts Antioxidant (Irganox 1010: Nippon Ciba-Geigy Corporation) 12 parts 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 coater, dried at 110 ° C. for 70 minutes to form a charge transport layer 2 having a dry film thickness of 2.0 μm, and the photoreceptor 1 is formed. Produced.

Production of Photoreceptors 2 to 12 Photoreceptor 1 was produced in the same manner as Photoreceptor 1 except that the type and amount of fluorine-based resin particles in charge transport layer 2 (CTL2) were changed as shown in Table 1. Body 2-12 was produced.

In Table 1,
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.

  A toner used in the present invention and a developer using the toner were prepared.

(Latex preparation)
A solution prepared by dissolving 7.08 g of an anionic active agent (sodium dodecylbenzenesulfonate: SDS) in ion-exchanged water (2760 g) in a 5000 ml separable flask equipped with a stirrer, temperature sensor, condenser, and nitrogen introducing device. Add. The internal temperature was raised to 80 ° C. while stirring at a stirring speed of 230 rpm under a nitrogen stream. On the other hand, Exemplified Compound 19) 72.0 g was added to a monomer composed of 115.1 g of styrene, 42.0 g of n-butyl acrylate, and 10.9 g of methacrylic acid, heated to 80 ° C. and dissolved, and a monomer solution was prepared. Produced.

  Here, the above heated solution was mixed and dispersed by a mechanical disperser having a circulation path to produce emulsified particles having a uniform dispersed particle size. Subsequently, a solution in which 0.84 g of a polymerization initiator (potassium persulfate: KPS) was dissolved in 200 g of ion-exchanged water was added, and the mixture was heated and stirred at 80 ° C. for 3 hours to prepare latex particles.

  Subsequently, a solution obtained by further dissolving 7.73 g of a polymerization initiator (KPS) in 240 ml of ion-exchanged water was added, and after 15 minutes, 383.6 g of styrene, 140.0 g of n-butyl acrylate, 36. A mixed solution of 4 g and 14.0 g of n-octyl-3-mercaptopropionic acid ester was dropped over 120 minutes. After completion of dropping, the mixture was heated and stirred for 60 minutes and then cooled to 40 ° C. to obtain latex particles. This latex particle is designated as Latex 1.

(Toner preparation example)
Production of colored particles 1 9.2 g of sodium n-dodecyl sulfate is dissolved in 160 ml of ion-exchanged water with stirring. Under stirring, 20 g of Legal 330R (carbon black manufactured by Cabot Corporation) was gradually added, and then dispersed using CLEARMIX. As a result of measuring the particle diameter of the dispersion using an electrophoretic light scattering photometer ELS-800 manufactured by Otsuka Electronics Co., Ltd., the weight average diameter was 112 nm. This dispersion is referred to as “colorant dispersion 1”.

  1250 g of the above-mentioned “Latex 1”, 2000 ml of ion-exchanged water, and “Colorant dispersion 1” are placed in a 5-liter four-necked flask equipped with a temperature sensor, a cooling tube, a nitrogen introducing device, and a stirring device and stirred. After adjusting to 30 ° C., a 5 mol / liter aqueous sodium hydroxide solution was added to this solution to adjust the pH to 10.0.

  Subsequently, an aqueous solution in which 52.6 g of magnesium chloride hexahydrate was dissolved in 72 ml of ion-exchanged water was added at 30 ° C. over 5 minutes with stirring. Thereafter, after standing for 2 minutes, temperature increase is started, and the temperature is increased to 90 ° C. in 5 minutes (temperature increase rate: 12 ° C./min). In that state, the particle size was measured with a Coulter Counter TA-II, and when the volume average particle size reached 4.3 μm, an aqueous solution in which 115 g of sodium chloride was dissolved in 700 ml of ion-exchanged water was added to stop particle growth. Further, the mixture is heated and stirred at a liquid temperature of 85 ° C. ± 2 ° C. for 8 hours to cause salting out / fusion.

  Then, it cooled to 30 degreeC on the conditions of 6 degreeC / min, hydrochloric acid was added, pH was adjusted to 2.0, and stirring was stopped. The produced colored particles were filtered / washed under the following conditions, and then dried with hot air at 40 ° C. to obtain colored particles. This is referred to as “colored particles 1”.

Production of Colored Particles 2 to 11 Colored particles 2 to 11 were produced by changing the production conditions for salting out / fusion in the production of the colored particles 1 as shown in Table 2.

  Next, 1% by mass of hydrophobic silica (number average primary particle size: 12 nm, degree of hydrophobicity: 68) and hydrophobic titanium oxide (number average primary particle size: 20 nm) are added to each of the “colored particles 1” to “colored particles 11”. Hydrophobic degree: 63) 1% by mass was added and mixed with a Henschel mixer to obtain a toner. These are referred to as “toner 1” to “toner 11”. The average particle diameter and particle size distribution of these toners were measured and shown in Table 3.

  The physical properties such as the average particle diameter and particle size distribution are substantially the same regardless of whether the toner particles are colored particles or toners (normally, external additives are added to the colored particles). There is no difference.

[Manufacture of developer]
Developers 1 to 11 for evaluation were produced by mixing 10 parts by weight of each of the toners 1 to 11 and 100 parts by weight of a 45 μm ferrite carrier coated with a styrene-methacrylate copolymer.

<Evaluation>
The obtained photoreceptor and developer were mounted in a commercially available color printer “magiccolor 2200 Desk Laser” (manufactured by Minolta EMS Co., Ltd.) in the combination shown in Table 4, and a durability test was performed. Specifically, a total of 20,000 original images including solid images, character images, and halftone images were printed and evaluated at the start and every 5,000 sheets. 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: Reversal development method Transfer: Use of intermediate transfer belt Cleaning: Cleaning blade Fixing: Heat fixing Process speed: 100 mm / 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. The measurement was performed on a solid black image portion after 20,000 copies were made.

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)
(Image unevenness)
A: Through the printing of 20,000 sheets, no streak-like unevenness was observed in any of the half images corresponding to the scratches on the surface of the photoreceptor;
○: 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)
A: No image blur was observed after printing 5,000 sheets (good)
○: Several partial image blurs (less than 10) occurred after printing 5,000 sheets, but there was no practical problem (no problem in practical use)
X: During printing of 5,000 sheets, 10 or more partial image blurs or 1 or more image blurs in a wide range occurred (practically problematic)
Dash Mark The occurrence of a dash mark on the halftone image was determined according to the following criteria.

A: Dash mark nuclei are not seen on the photoconductor, and no dash marks are generated on halftone images (good)
○: Dash mark nuclei are seen on the photoreceptor, but no dash marks are generated in the halftone image (no problem in practical use)
×: Dash mark nuclei are seen on the photoconductor, and dash marks are also generated in halftone images (practical problems)
(Sharpness)
The sharpness of the image 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 the results of Table 4, it contains fluororesin fine particles and binder resin 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 contact angle with water is 90 ° or more. When an organic photoreceptor (No. 1) having a surface layer (= charge transport layer 2) having a contact angle variation of ± 2.0 ° is used and the 50% number particle diameter of toner particles is Dp50, the particle diameter The combinations of developers (Nos. 1-3, 5-9, and 11) using toner in which the number of toner particles having a particle size of 0.7 × (Dp50) or less is 10% by number or less are (Combination Nos. 1 to 3). 5-9 and 11), all the photoreceptors have improved image unevenness, image blurring, dash marks and sharpness, and have obtained good electrophotographic images. Further, the developer 1 using the toner satisfying the conditions of the present invention and the fluorine-containing resin fine particles and binder resin 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% In combination with an organic photoreceptor having a surface layer (= charge transport layer 2) having a contact angle with water of 90 ° or more and a variation in contact angle of ± 2.0 ° (combination Nos. 12 and 13). 16, 18, 20 to 22) have improved image unevenness, image blurring, dash marks and sharpness, and have obtained good electrophotographic images.
Developers (Nos. 4, 7, and 10) using toners that do not have the conditions of the present invention can be combined with the photoreceptor 1 that satisfies the conditions of the present invention (combination Nos. 4, 7, and 10). , Combination No. In No. 4, fogging and dash marks occurred, sharpness deteriorated. 7 and 10 also cause image degradation due to fog and dash marks.

  On the other hand, in combination No. 4 using photoreceptor 4 (fluorine-containing resin particles having poor dispersibility and large contact angle variation of 2.2) using fluorine-containing resin particles having an average primary particle size of 0.01 μm. No. 14 is a combination No. 14 using a photoreceptor 5 (a variation in contact angle is as large as 2.3) using fluorine-containing resin particles having a dash mark and an average primary particle size of 0.22 μm. No. 15 has dash marks and image blurring, and sharpness is deteriorated. In addition, in combination No. 7 using a photoreceptor 7 using fluorine-containing particles having a crystallinity of 91.3% (the spreadability of the fluorine-containing particles is small and the contact angle variation is as large as 2.2). No. 17 has dash marks and image unevenness, and sharpness is deteriorated. In addition, the combination No. 1 using the photoconductor 9 (the contact angle is low at 88 ° and the contact angle variation is as large as 2.4) in which the content of the fluorine-containing resin particles is reduced. No. 19, dash marks and image irregularities occur, and the sharpness deteriorates.

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 (7)

In an image forming apparatus having an organic photoreceptor and a charging means for forming an electrostatic latent image on the organic photoreceptor, an exposure means, and a developing means for developing the electrostatic latent image into a toner image. The organic photoreceptor contains fluorine-containing resin fine particles and a binder resin 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 a contact angle with water of 90 ° or more. And having a surface layer with a variation in contact angle of ± 2.0 °, where the developing means has a particle size of 0.7 × (Dp50) or less, where Dp50 is the 50% number particle size of the toner particles. An image forming apparatus comprising a toner in which the number of toner particles is 10% by number or less. In an image forming apparatus having an organic photoreceptor and a charging means for forming an electrostatic latent image on the organic photoreceptor, an exposure means, and a developing means for developing the electrostatic latent image into a toner image. The organic photoreceptor contains fluorine-containing resin fine particles and a binder resin 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 a contact angle with water of 90 ° or more. And having a surface layer with a variation in contact angle of ± 2.0 °, and the developing means has a ratio (Dv50 / 50) of 50% volume particle diameter (Dv50) to 50% number particle diameter (Dp50) of toner particles. Dp50) is 1.0 to 1.15, and the ratio of the cumulative 75% volume particle size (Dv75) from the larger volume particle size to the cumulative 75% number particle size (Dp75) from the larger number particle size (Dv75 / Dp75) is 1.0 to 1.20, and An image forming apparatus comprising a toner having a particle diameter of 0.7 × (Dp50) or less and having 10 or less number of toner particles. The image forming apparatus according to claim 1, wherein at least one of the binder resins is a siloxane-modified polycarbonate. The image forming apparatus according to claim 1, wherein the fluororesin fine particles coexist with an antioxidant. The organic photoconductor has a charge generation layer and a plurality of charge transport layers on a conductive support, and the uppermost layer of the plurality of layers is a surface layer. The image forming apparatus described in the item. In an image forming method in which an electrostatic latent image is formed on an organic photoreceptor and the electrostatic latent image is visualized by a developing means to form an electrophotographic image, the organic photoreceptor has an average primary particle size of 0. It contains fluorine-containing resin fine particles and binder resin having a crystallinity of less than 90% and not less than 0.2 μm and less than 0.20 μm, the contact angle with water is 90 ° or more, and the contact angle variation is ± 2.0 °. A toner having a certain surface layer and the developing means has a toner particle number of not more than 10% by number of toner particles having a particle size of 0.7 × (Dp50) or less, where Dp50 is a 50% number particle size of toner particles. An image forming method comprising: In an image forming method in which an electrostatic latent image is formed on an organic photoreceptor and the electrostatic latent image is visualized by a developing means to form an electrophotographic image, the organic photoreceptor has an average primary particle size of 0. It contains fluorine-containing resin fine particles and binder resin having a crystallinity of less than 90% and not less than 0.2 μm and less than 0.20 μm, the contact angle with water is 90 ° or more, and the contact angle variation is ± 2.0 °. And the developing means has a ratio (Dv50 / Dp50) of 50% volume particle diameter (Dv50) to 50% number particle diameter (Dp50) of toner particles of 1.0 to 1.15, The ratio (Dv75 / Dp75) of the cumulative 75% volume particle diameter (Dv75) from the larger volume particle diameter to the cumulative 75% number particle diameter (Dp75) from the larger number particle diameter is 1.0 to 1.20. Toner particles having a particle size of 0.7 × (Dp50) or less Image forming method characterized in that the number contains a toner is 10% by number or less.

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