JP4324014B2 - Developer carrier and developing method using the same - Google Patents

Description

  The present invention relates to a developer carrier used in a developing device for developing an electrostatic latent image formed on an image carrier such as an electrophotographic photosensitive member or an electrostatic recording derivative to form a toner image. The present invention also relates to a developing method using the developer carrying member.

  Conventionally, an electrophotographic method uses a photoconductive substance, forms an electrostatic latent image on an electrostatic latent image holding member (photosensitive drum) by various means, and then converts the electrostatic latent image into a developer (toner). Development is performed to form a toner image, and if necessary, the toner image is transferred to a transfer material such as paper. Then, the toner image is fixed on the transfer material by heat, pressure or heat and pressure, and printed or copied. Is what you get.

  Development methods in electrophotography are mainly divided into a one-component development method and a two-component development method. In recent years, since it is necessary to reduce the size of a developing device for the purpose of reducing the weight and size of an electrophotographic apparatus, a developing device using a one-component developing system is often used.

  Since the one-component development method does not require carrier particles unlike the two-component development method, the development device itself can be reduced in size and weight. On the other hand, since the two-component development method needs to keep the toner concentration in the developer constant, a device for detecting the toner concentration and supplying a necessary amount of toner is required. Therefore, the developing device becomes large and heavy. In the one-component development method, such an apparatus is not necessary, and thus it can be made small and light.

  As a developing device using a one-component developing system, an electrostatic latent image is formed on the surface of a photosensitive drum as an electrostatic latent image carrier, and the friction between the developer carrier (developing sleeve) and toner and / or the developing sleeve. The friction between the developer layer thickness regulating member for regulating the toner coating amount and the toner gives positive or negative triboelectric charge to the toner. Then, the toner to which the triboelectric charge is applied is thinly applied onto the developing sleeve and conveyed to a developing area where the photosensitive drum and the developing sleeve face each other, and the toner is adhered to the electrostatic latent image on the surface of the photosensitive drum in the developing area. Develop to form a toner image.

  When such a one-component development method is used, the toner needs to be uniformly charged and sufficient durability stability is required.

  In particular, while the developing sleeve is repeatedly rotated, the charge amount of the toner coated on the developing sleeve becomes too high due to contact with the developing sleeve, and the toner is attracted by the reflection force on the developing sleeve surface and developed. A charge-up phenomenon that becomes immobile on the surface of the sleeve and does not move from the developing sleeve to the electrostatic latent image on the photosensitive drum is likely to occur particularly under low humidity. When the charge-up phenomenon occurs, the toner in the upper layer is difficult to be charged and the development amount of the toner is reduced, which may cause a problem that the line image is thin and the solid image is thin. Further, the toner that is not properly charged due to the charge-up phenomenon may be poorly regulated and may flow out onto the developing sleeve, resulting in blotch and wavy irregularities.

  Furthermore, since the toner layer formation state of the image portion (toner consumption portion) and the non-image portion is changed and the charging state is different, the position where the solid image having a high image density is developed once on the developing sleeve is the developing sleeve. When the halftone image is developed at the development position during the next rotation, a sleeve ghost phenomenon in which a solid image trace appears on the image is likely to occur.

  Recently, in order to digitize an electrophotographic apparatus and further increase the image quality, the toner is reduced in particle size and particle size. For example, in order to improve resolution and character sharpness and faithfully reproduce an electrostatic latent image, it is common to use toner having a weight average particle diameter of about 5 to 12 μm.

  In addition, printers are required to be downsized in terms of energy saving and office space saving. Containers for storing toner in printers are inevitably required to be miniaturized, and it is necessary to use low consumption toner that can print out a large number of sheets with a small amount. As a low consumption toner, a toner in which the shape of the toner particle toner is close to a spherical shape has been used.

  Furthermore, the toner fixing temperature tends to be lowered for the purpose of shortening the first copy time and saving power.

  Under such circumstances, especially in toners at low temperatures and low humidity, the amount of charge per unit mass increases, so that the toner is more likely to adhere electrostatically onto the developing sleeve. Contamination and fusion are likely to occur.

  As a method for solving such a phenomenon, in JP-A-1-276174, development in which a resin coating layer in which conductive fine powders such as crystalline graphite and carbon are dispersed in a resin is provided on a metal substrate is disclosed. It has been proposed to use a sleeve in a developing device. By using this developing sleeve, it is recognized that the above phenomenon is greatly reduced.

  However, in this developing sleeve, when a large amount of conductive fine powder is added to the resin, it is good for charge-up and sleeve ghosting, but the ability to impart electrification to the toner is reduced, especially at high temperatures. It is difficult to obtain a high image density in a high humidity environment. In addition, when a large amount of conductive fine powder is added, the resin coating layer becomes brittle and is easily scraped and the surface shape tends to be non-uniform. The surface composition changes, and toner conveyance failure and non-uniform charge application to the toner are likely to occur.

  In particular, a developing device having a developing sleeve using a coating layer in which crystalline graphite particles are dispersed as described in Patent Document 1 has been proposed. The crystalline graphite particles used are artificial graphite or natural graphite obtained by solidifying a bone agent such as coke with tar pitch and firing it at about 1000 to 1300 ° C. and then graphitizing at about 2500 to 3000 ° C. Crystalline graphite particles made of Therefore, the crystalline graphite has lubricity due to the flake-like structure, so that it is effective against charge-up and sleeve ghost. However, the shape of the crystalline graphite particles is flake shaped and irregular, and when dispersed in the resin coating layer, the particle size is small and difficult to disperse uniformly, and the surface shape of the resin coating layer is non-uniform. In some cases, fusion due to toner may occur due to uneven unevenness formed by crystalline graphite.

  Furthermore, since the crystalline graphite has a low hardness, the crystalline graphite particles themselves are likely to be worn and detached on the surface of the resin coating layer. The composition is likely to change, the toner is more likely to be fused, and the toner is poorly conveyed and the toner is not easily charged. On the other hand, when the amount of conductive fine powder such as carbon added to the resin coating layer formed on the metal substrate of the developing sleeve is small, the effect of the crystalline graphite particles and the conductive fine powder is small and the charge is increased. And sleeve ghost may occur.

  Patent Document 2 proposes a developing device having a developing sleeve in which a conductive resin coating layer in which conductive fine powders such as crystalline graphite and carbon and spherical particles are dispersed in a resin is provided on a metal substrate. Has been. In this developing sleeve, the wear resistance of the resin coating layer is improved, the shape of the surface of the resin coating layer is made uniform, and the change in surface roughness due to the durability of a large number of sheets is relatively small. The coating of the toner can be stabilized and the charge of the toner can be made uniform, problems such as sleeve ghost, image density and image density unevenness are reduced, and the image quality tends to be stabilized. However, in this developing sleeve, it is preferable to further improve the quick and uniform charge controllability to the toner and the stabilization of an appropriate charge imparting ability to the toner. In addition, in terms of abrasion resistance, the change in surface roughness or roughness of the resin coating layer caused by wear or fall off of the spherical particles or crystalline graphite of the resin coating layer in the developing sleeve due to further long-term use. Of the resin coating layer, toner contamination and toner fusing of the resin coating layer easily occur. In such a case, the charging of the toner becomes unstable and tends to cause image defects such as image density reduction, density unevenness, fog, and image streaks.

  In Patent Document 3, the spherical particles dispersed in the conductive resin coating layer are conductive spherical particles having a low specific gravity, whereby the conductive spherical particles are uniformly dispersed in the conductive resin coating layer. As a result, the wear resistance of the resin coating layer and the electrical conductivity of the surface of the resin coating layer are made uniform, and the uniform charge imparting property to the toner is improved. A developing device having a developing sleeve capable of suppressing toner fusion has been proposed. However, there is a point to be improved in this developing sleeve in terms of quick and uniform chargeability to the toner and moderate chargeability to the toner. In addition, in long-term durable use, since the shape of the portion of the resin coating layer where the conductive spherical particles do not exist is uneven and the wear resistance of the portion is inferior, Conductive particles such as conductive graphite tend to wear or fall off. From the worn and dropped parts and the uneven parts of the shape, the resin coating layer is worn, the toner is contaminated, and the toner is fused.

  In Patent Documents 4 to 7, toners that are spherical or nearly spherical are proposed. A developing sleeve and a developing device that are effective in reducing the consumption of these toners and stabilizing the developability of the toner by durability are desired.

Patent Documents 8 to 11 propose toners in which toner particles produced by a pulverization method are modified in shape and surface properties by thermal or mechanical impact. A developing sleeve and a developing device that are effective in reducing the consumption of these toners and stabilizing the developability of the toner by durability are desired.
JP-A-1-276174 Japanese Patent Laid-Open No. 3-200986 JP-A-8-240981 Japanese Patent Laid-Open No. 3-84558 JP-A-3-229268 Japanese Patent Laid-Open No. 4-1766 JP-A-4-102862 JP-A-2-87157 JP-A-10-97095 JP-A-11-149176 JP-A-11-202557

  An object of the present invention is to provide a developer carrying member and a developing method which have solved the above problems.

  It is an object of the present invention to stably obtain a high-quality image having a high image density without causing problems such as density reduction, image density unevenness, image streaks, sleeve ghost, and fog even under different environmental conditions. It is an object of the present invention to provide a developer carrying member that can be developed and a developing method using the developer carrying member.

  Another object of the present invention is to reduce toner adhesion and toner fusion on the surface of the developer carrying member, which appears when an image is formed using toner having a small particle diameter or toner having a high sphericity. Accordingly, an object of the present invention is to provide a developer carrying body that can control non-uniform charging of the toner and quickly give an appropriate charge to the toner, and a developing method using the developer carrying body.

  Another object of the present invention is to provide a developer carrier that is less likely to cause deterioration of the resin coating layer on the surface of the developer carrier due to repeated development or durable use, has high durability, and provides stable image quality. An object of the present invention is to provide a developing method using the developer carrying member.

  Furthermore, the object of the present invention is to impart a proper charge quickly and uniformly to the toner on the developer carrying member even in continuous development over a long period of time, and to provide a stable charge without causing a charge-up, It is an object of the present invention to provide a developer carrying body that can obtain a high-quality image free from image density reduction and density unevenness, sleeve ghost, fog, and image streaking during durable use, and a developing method using the developer carrying body.

  As a result of intensive studies to solve the above problems, the present inventors have found that the resin-coated layer on the surface of the developer-carrying member is uniformly and finely coated with graphitized particles having a specific range of graphitization degree. The irregularities formed on the coating layer by the graphitized particles are finely controlled within a specific range, and the arithmetic average roughness Ra of the coating layer surface is 0.9 to 2.5 μm. The structure in which the rough particles are uniformly dispersed has no effect on toner charge-up, toner contamination, and toner fusion, and has an effect of imparting an appropriate charge amount to the toner quickly and uniformly. The inventor found out.

  Further, by configuring the developer carrying member as described above, the surface covering layer roughness, surface shape uniformity, and surface material composition of the developer carrying member can be improved even when a large number of images are printed under different environments. The present inventor has found an effect capable of suppressing the change.

That is, the developer carrier according to the present invention is a developer carrier that carries a one-component developer for visualizing the electrostatic latent image carried on the electrostatic latent image carrier, and the developer carrier. The body has at least a substrate and a resin coating layer formed on the surface of the substrate, and the resin coating layer contains at least graphitized particles and coarse particles,
The rough particles are composed of spherical conductive carbon particles having a volume average particle diameter of 8.7 to 18.8 μm,
The graphitized particles are particles obtained by baking bulk mesophase pitch particles or mesocarbon microbeads composed of a single phase and graphitizing the degree of graphitization p (002) to 0.23 to 0.79, and In the resin coating layer, the volume average particle size is dispersed so as to be 1.0 to 3.6 μm, and thereby the surface shape of the resin coating layer measured using a focusing optical system laser is roughened. The volume B of the fine irregularities formed by the graphitized particles in the constant area A of the region where the convexities are not formed by the particles satisfies the relationship of 4.7 ≦ B / A ≦ 6.2. Further, the arithmetic average roughness Ra of the resin coating layer surface is 0.9 to 2.5 μm.
Further, in the developing method according to the present invention, the one-component developer is transported to the developing region facing the electrostatic latent image carrier using the developer-carrying member carrying the one-component developer. In the developing method including the step of developing the electrostatic latent image carried on the electrostatic latent image carrier by the one-component developer, the developer carrier is the developer carrier described above. And

  According to the present invention, it is possible to stably obtain a high-quality image having a high image density without causing problems such as density reduction, image density unevenness, image streak, sleeve ghost, and fog even under different environmental conditions. A developer carrying body capable of developing, and a developing and developing method using the developer carrying body can be provided.

  Further, according to the present invention, by reducing toner adhesion and fusion to the surface of the developer carrying member, which appears when image formation is performed using toner having a small particle diameter or toner having a high sphericity, It is possible to provide a developer carrying body that can control non-uniform charging of the toner and quickly give an appropriate charge to the toner, and a developing and developing method using the developer carrying body.

  In addition, according to the present invention, the developer carrying member that is less likely to cause deterioration of the resin coating layer on the surface of the developer carrying member due to repeated copying or durable use, has high durability, and obtains a stable image quality, A developing method using a developer carrying member can be provided.

  In addition, according to the present invention, even in continuous copying over a long period of time, the toner on the developer carrying member is quickly and uniformly given appropriate charge, and a stable charge is always given without causing charge-up. Further, it is possible to provide a developer carrying body capable of obtaining a high-quality image free from image density reduction and density unevenness, sleeve ghost, fog, and image streaking during durable use, and a developing method using the developer carrying body. .

  The present invention will be described in detail by giving preferred embodiments. The developer carrier of the present invention will be described.

The developer carrier of the present invention is a developer carrier that carries a one-component developer for visualizing an electrostatic latent image carried on the electrostatic latent image carrier, and the developer carrier comprises: Having at least a substrate and a resin coating layer formed on the surface of the substrate, the resin coating layer containing at least graphitized particles and coarse particles,
The rough particles are composed of spherical conductive carbon particles having a volume average particle diameter of 8.7 to 18.8 μm,
The graphitized particles are particles obtained by baking bulk mesophase pitch particles or mesocarbon microbeads composed of a single phase and graphitizing the degree of graphitization p (002) to 0.23 to 0.79, and In the resin coating layer, the volume average particle size is dispersed so as to be 1.0 to 3.6 μm, and thereby the surface shape of the resin coating layer measured using a focusing optical system laser is roughened. The volume B of the fine irregularities formed by the graphitized particles in the constant area A of the region where the convexities are not formed by the particles satisfies the relationship of 4.7 ≦ B / A ≦ 6.2. And
Further, the arithmetic average roughness Ra of the resin coating layer surface is 0.9 to 2.5 μm.

The graphitization degree p (002) is the Franklin p value, and is a value obtained by using the following formula (1) by measuring the lattice spacing d (002) obtained from the X-ray diffraction pattern of graphite. is there.
d (002) = 3.440−0.086 [1-p (002) ² ] (1)
This p (002) value indicates the ratio of disordered portions in the stacking of hexagonal mesh planes of carbon. The smaller the p (002) value, the higher the graphitization crystallinity.

  The graphitized particles used in the present invention are obtained by hardening a bone agent such as coke described in JP-A-1-276174 with a tar pitch and firing it at about 1000 to 1300 ° C. and then firing it at about 2500 to 3000 ° C. The raw material and the manufacturing process are different from those of the conventional crystalline graphite made of artificial graphite or natural graphite obtained by graphitization with the above method. Although the degree of graphitization is slightly lower than that of crystalline graphite, the graphitized particles used in the present invention have high conductivity and lubricity similar to crystalline graphite. Furthermore, the graphitized particles used in the present invention are characterized in that the shape of the crystalline graphite is different from the shape of scales or needles, and the shape of the particles is particulate and the hardness of the particles themselves is relatively high. It is.

  The graphitized particles used in the present invention are different from the raw materials and the production method of the low specific gravity and conductive spherical particles described in JP-A-8-240981, and the properties of the particles and the effect of the particles on the resin coating layer Is different.

  Low specific gravity and conductive spherical particles described in JP-A-8-240981 include phenol resin, naphthalene resin, furan resin, xylene resin, divinylbenzene polymer, styrene-divinylbenzene copolymer, polyacrylonitrile and the like. The surface of the spherical resin particles is coated with a bulk mesophase pitch by a mechanochemical method, and the coated particles are heat-treated in an oxidizing atmosphere and then calcined in an inert atmosphere or in a vacuum to be carbonized and / or graphite. It has become. Accordingly, since the spherical resin particle itself is a material that is difficult to graphitize, even if the surface is graphitized, the inside of the particle is carbonized, and the degree of graphitization p (002) of the particle itself cannot be measured. The crystallinity is different from the graphitized particles used in the invention. In addition, when the conductive spherical particles are dispersed in the resin coating layer, the resin coating layer has a function of increasing the toner conveyance force, increasing the contact opportunity of the toner, and improving the wear resistance of the resin coating layer. Has been granted.

  On the other hand, the graphitized particles used in the present invention provide uniform and minute irregularities on the surface of the resin coating layer, thereby providing uniform properties such as lubricity, conductivity, charge imparting properties, and wear resistance. It is added in the resin coating layer to give to the layer.

  The graphitized particles used in the present invention are easily dispersed uniformly and finely in the resin coating layer, and the fine irregularities formed on the surface of the resin coating layer by the graphitized particles can be easily controlled to an appropriate size. By forming these minute irregularities on the surface of the resin coating layer, the contact area with the surface of the toner is controlled to improve the releasability of the toner and make it easier to charge the toner uniformly. In addition, the charging effect and lubricity effect are further exhibited, and the toner is quickly and uniformly charged stably without causing toner charge-up, toner contamination, and toner fusion on the surface of the resin coating layer. Is possible.

  In addition, the graphitized particles used in the present invention have excellent lubricity and the hardness of the resin coating layer is small due to a small difference in hardness from the coating resin because of the appropriate hardness. However, it is difficult to scrape due to the durability of a large number of sheets. For this reason, even if the surface of the resin coating layer of minute uneven portions is scraped, it is easy to cut evenly, so the minute uneven shape is maintained, and the composition and characteristics of the surface of the resin coating layer change even if many sheets endure It is difficult to do.

The graphitized particles used in the present invention have a graphitization degree p (002) of 0.23 to 0.79 .

  When the graphitization degree p (002) of the graphitized particles exceeds 0.95, the resin coating layer is excellent in wear resistance, but the conductivity and lubricity are lowered, and the toner is charged up and fused. In some cases, image quality such as sleeve ghost, fogging, and image density tends to deteriorate. In particular, when an elastic blade and toner having a high sphericity are used in the developing process, streaks and density unevenness are likely to occur in the image due to toner fusion on the surface of the developing sleeve. On the other hand, when the degree of graphitization p (002) of the graphitized particles is less than 0.20, the wear resistance of the surface of the resin coating layer decreases due to the decrease in the hardness of the graphitized particles, and the graphite on the surface of the resin coating layer. It is difficult to maintain the fine uneven shape imparted by the particles, and the composition of the surface of the resin coating layer is likely to change, which may cause toner charge-up and toner fusing.

The graphitization degree p (002) of the graphitized particles is measured by a lattice spacing d (002) obtained from the X-ray diffraction spectrum of the graphitized particles by a powerful fully automatic X-ray diffractometer “MXP18” system manufactured by Mac Science. ) And is obtained by d (002) = 3.440−0.086 [1-p (002) ² ].

The lattice spacing d (002) uses CuKα as an X-ray source, and CuKβ rays are removed by a nickel filter. High-purity silicon is used as the standard substance, and the calculation is performed from the peak positions of the C (002) and Si (111) diffraction patterns. The main measurement conditions are as follows.
X-ray generator: 18 kW
Goniometer: Horizontal goniometer Monochromator: Working tube voltage: 30.0kV
Tube current: 10.0mA
Measurement method: Continuous method Scan axis: 2θ / θ
Sampling interval: 0.020 deg
Scan speed: 6.000 deg / min
Divergence slit: 0.50deg
Scattering slit: 0.50deg
Receiving slit: 0.30mm
As a method for obtaining graphitized particles having a graphitization degree p (002) 0.20 to 0.95, the following methods are preferable, but are not necessarily limited to these methods.

  As a preferred method for obtaining graphitized particles used in the present invention, graphitization is performed using mesocarbon microbeads or bulk mesophase pitch particles having optical anisotropy as a raw material and consisting of a single phase. It is preferable to increase the degree of graphitization of the graphitized particles and maintain appropriate hardness and dispersibility while maintaining lubricity.

  The optical anisotropy of the raw material is caused by the lamination of aromatic molecules, and the order is further developed by the graphitization treatment, and graphitized particles having a high degree of graphitization are obtained.

  When bulk mesophase pitch is used as a raw material for obtaining graphitized particles used in the present invention, it is preferable to use bulk mesophase pitch that softens and melts under heating. Preferred for obtaining particles.

  As a method for obtaining bulk mesophase pitch, there is a method for obtaining bulk mesophase pitch by extracting β-resin from a raw material such as coal tar pitch by solvent fractionation, hydrogenating β-resin, and performing a heavy treatment. . In the above method, bulk mesophase pitch may be obtained by pulverizing after the heavy treatment and then removing the solvent-soluble component with a solvent such as benzene or toluene.

  The bulk mesophase pitch preferably has a quinoline soluble content of 95% by mass or more. When a bulk mesophase pitch having a quinoline-soluble content of less than 95% by mass is used, the inside of the particles of the bulk mesophase pitch is difficult to be liquid phase carbonized, so the shape of the carbonized particles remains crushed because of solid phase carbonization, The shape of the particles tends to be non-uniform and poor dispersion tends to occur. A method for graphitizing the bulk mesophase pitch obtained as described above will be described below. The bulk mesophase pitch is finely pulverized to 2 to 25 μm, and the finely pulverized bulk mesophase pitch is heat-treated in air at about 200 to 350 ° C. to be lightly oxidized. By this oxidation treatment, the bulk mesophase pitch particles are infusibilized only on the surface, and melting and fusing during the graphitizing firing in the next step are prevented. The oxidized bulk mesophase pitch particles preferably have an oxygen content of 5 to 15% by mass. If the oxygen content is less than 5% by mass, fusion between particles during heat treatment is likely to occur, and if it exceeds 15% by mass, the inside of the particle is oxidized and graphitized while the particle shape remains crushed. In this case, the dispersibility deteriorates.

  Next, the oxidized bulk mesophase pitch particles are carbonized by primary firing at about 800 to 1200 ° C. in an inert atmosphere such as nitrogen and argon, followed by secondary firing at about 2000 to 3500 ° C. By doing so, desired graphitized particles can be obtained.

  In addition, representative examples of methods for obtaining mesocarbon microbeads, which are another preferred raw material for obtaining graphitized particles used in the present invention, are given below. Coal heavy oil or petroleum heavy oil is heat-treated at a temperature of 300 to 500 ° C. and subjected to a polycondensation reaction to produce crude mesocarbon microbeads. The obtained reaction product is treated by filtration, stationary sedimentation, centrifugation, etc. to separate the mesocarbon microbeads, and then the mesocarbon microbeads are washed with a solvent such as benzene, toluene, xylene, and further dried. By doing so, mesocarbon micro beads as a raw material can be obtained.

  When graphitizing the obtained mesocarbon microbeads, it is possible to prevent the coalescence of the particles in the carbonization process and to maintain a uniform particle size by mechanically dispersing the dried mesocarbon microbeads with a gentle force that does not cause destruction. It is preferable to obtain

  The mesocarbon microbeads that have finished primary dispersion are primarily fired and carbonized at a temperature of 200 to 1500 ° C. in an inert atmosphere. In order to prevent coalescence in the graphitization step and to obtain a uniform particle size, it is preferable that the carbide particles after the primary firing have mechanically dispersed the carbide particles with a mild force that does not destroy the carbide particles. .

  The carbide after the primary firing is subjected to secondary firing at about 2000 to 3500 ° C. in an inert atmosphere, whereby desired graphitized particles are obtained.

  In order to make the surface shape of the resin coating layer uniform, it is preferable that the graphitized particles obtained from any raw material and production method have a uniform particle size distribution to some extent by classification.

  Moreover, also in the manufacturing method of the graphitized particle using any raw material, it is preferable that the baking temperature of graphitization is 2000-3500 degreeC, and it is more preferable that it is 2300-3200 degreeC.

  When the graphitization firing temperature is less than 2000 ° C., the degree of graphitization of the graphitized particles may decrease, and the conductivity and lubricity may decrease, causing toner charge-up and toner fusing. , Fog and image density are low. In particular, when an elastic blade and toner having a high sphericity are used in the developing process, streaks and density unevenness are likely to occur in the image due to toner fusion on the surface of the developing sleeve. In addition, when the firing temperature is higher than 3500 ° C., the graphitization degree of the graphitized particles may be too high. Graphitized particles having a high degree of graphitization are reduced in hardness, and the wear resistance of the surface of the resin coating layer decreases due to the decrease in the hardness of the graphitized particles. It is difficult to maintain an uneven shape, and the surface composition of the resin coating layer is also changed, which may cause toner charge-up and toner fusion.

  In the resin coating layer constituting the developer carrying member of the present invention, coarse particles are dispersed together with graphitized particles in the resin coating layer. Roughening particles maintain a suitable surface roughness on the surface of the resin coating layer of the developer carrier to improve toner conveyance, increase the chance of contact between the toner as a bulk and the resin coating layer, and resin coating. This has the effect of improving the abrasion resistance of the layer and further reducing the pressure applied to the toner from the elastic blade when the elastic blade is used, thereby making it difficult to cause toner fusion.

True density of roughening particles for use in the present invention, is preferably 3 g / cm ³ or less, more preferably 2.7 g / cm ³ or less, are 0.9~2.3g / cm ³ More preferably. When the true density of the roughened particles exceeds ³ g / cm ³ , the dispersibility of the roughened particles in the resin coating layer is lowered, so that it is difficult to impart uniform roughness to the surface of the resin coating layer. The uniform triboelectric chargeability of the toner and the strength of the resin coating layer are likely to decrease. Even when the true density of the roughened particles is smaller than 0.9 g / cm ³ , the dispersibility of the roughened particles in the resin coating layer may be lowered.

The shape of the rough particles used in the present invention is preferably spherical, and the following formula (2): circularity = (4 × A) / {(ML) ² × π} (2)
[In the formula, ML represents the maximum length of the Pythagorean method of the particle projection image, and A represents the area of the particle projection image. ]
The average circularity SF-1 that is the average value of the circularity obtained by the above is preferably 0.75 or more, and more preferably 0.80 or more.

  In the present invention, as a specific method for obtaining the average circularity SF-1 described above, a rough particle projection image enlarged by an optical system is taken into an image analysis apparatus, and the circularity value for each particle is obtained. Is calculated and averaged.

  In the present invention, reliability is obtained as an average value, and the circularity is measured by limiting to a particle range having a circle-equivalent diameter of 2 μm or more, which has a great influence on the properties of the resin coating layer. In order to obtain the reliability of these values, the number of measured particles is about 3000 or more, preferably 5000 or more.

  As a specific measuring apparatus capable of efficiently analyzing the circularity of a large number of roughened particles as described above, for example, there is a multi-image analyzer (manufactured by Beckman Coulter).

  The multi-image analyzer is a combination of a particle size distribution measuring apparatus based on an electrical resistance method and a function of photographing a particle image with a CCD camera and a function of analyzing the photographed particle image. Specifically, the measurement particles dispersed uniformly in the electrolyte solution by ultrasonic waves or the like are detected by the change in electric resistance when the particles pass through the aperture of the multisizer, which is a particle size distribution measuring device by the electric resistance method. Synchronously, a strobe is emitted and a particle image is taken with a CCD camera. This particle image is taken into a personal computer and analyzed after binarization.

  Obtain the Pythagorean method maximum length ML and projected area A of the projected particle image using the above-mentioned apparatus, calculate the circularity value for 3000 or more particles of 2 μm or more from the above equation (2), and average these values To obtain the average circularity SF-1.

  When the average circularity SF-1 is less than 0.75, the dispersibility of the rough particles in the resin coating layer is reduced, and unevenness of the resin coating layer surface roughness is likely to occur. There are cases where toner fusion occurs on the surface of the developing sleeve, the uniform triboelectric chargeability of the toner is lowered, and the strength of the resin coating layer is lowered.

The rough particles used in the present invention are highly conductive spherical carbon particles .

Spherical particles used in the present invention are electrically conductive. This is because by imparting conductivity to the spherical particles, triboelectric charges are unlikely to accumulate on the surface of the spherical particles, and the toner adhesion can be reduced and the charge imparting property to the toner can be improved.

In the present invention, the spherical particles preferably have a volume resistance of 10 ⁶ Ω · cm or less, more preferably 10 ⁻³ to 10 ⁶ Ω · cm. If the volume resistance of the spherical particles exceeds 10 ⁶ Ω · cm, the spherical particles exposed on the surface of the resin coating layer due to wear tend to cause toner contamination and fusion, and rapid and uniform frictional charging is achieved. It becomes difficult to be done.

  As a particularly preferable method for obtaining conductive spherical particles, there is a method for obtaining low-density and good-conductive spherical carbon particles obtained by carbonizing and / or graphitizing by firing resin-based spherical particles or mesocarbon microbeads. Can be mentioned. Examples of the resin used for the resin-based spherical particles include phenol resin, naphthalene resin, furan resin, xylene resin, divinylbenzene polymer, styrene-divinylbenzene copolymer, and polyacrylonitrile. Mesocarbon microbeads can usually be produced by washing spherical crystals produced in the course of heating and firing the medium pitch with a large amount of a solvent such as tar, medium oil and quinoline.

  More preferable methods of obtaining conductive spherical particles include phenolic resin, naphthalene resin, furan resin, xylene resin, divinylbenzene polymer, styrene-divinylbenzene copolymer, mechanochemical on the surface of spherical resin particles such as polyacrylonitrile. A method in which bulk mesophase pitch is coated by a method, and the coated particles are heat-treated in an oxidizing atmosphere and then calcined in an inert atmosphere or vacuum to be carbonized and / or graphitized to obtain conductive spherical carbon particles. Can be mentioned. Spherical carbon particles obtained by this method are more preferred because they improve the conductivity because the crystallization of the coating of the spherical carbon particles obtained by the graphitization proceeds.

  The conductive spherical carbon particles obtained by the above-described method can control the conductivity of the spherical carbon particles obtained by changing the firing conditions in any method, and are preferably used in the present invention. . In addition, the spherical carbon particles obtained by the above-described method may contain conductive metals and / or metal oxides as long as the true density of the conductive spherical particles does not become too high in order to further increase the conductivity. It may be plated.

In addition, the resin coating layer of the developer carrying member of the present invention is measured in a constant area A of a minute uneven region portion in which a convex portion is not formed by rough particles in a surface shape measured using a focus optical system laser. The volume B of the shape of the minute uneven portion satisfies the relationship of 4.7 ≦ B / A ≦ 6.2 .

  The measurement of the volume B of the shape of the minute uneven part measured by the constant area A of the minute uneven part where the convex part is not formed by the rough particles is, for example, an ultra-deep shape measurement microscope VK-8500 (manufactured by KEYENCE). ). This device measures the shape of an object based on objective lens position information in which the amount of reflected light received by the light receiving element at the confocal position is maximized by applying the laser emitted from the light source to the object and reflecting the laser reflected from the object. Is.

As measurement conditions, the surface of the resin coating layer was observed at a magnification of 2000 using a 100 × objective lens, and the surface of the resin coating layer was rough and 20 μm in the horizontal direction where no convexity formed by particles was present. Measurement is performed by appropriately selecting a region having an area A (4 × 10 ⁻¹⁰ m ² ) of 20 μm in the vertical direction and then setting the lens movement amount in the height direction to 0.1 μm. The measurement result is analyzed by the image analysis software VK-H1W (manufactured by KEYENCE), and the volume B (m ³ ) of the minute uneven portion observed at the area A (4 × 10 ⁻¹⁰ m ² ) in the measurement region is calculated. To do. As a measurement location, 20 or more points are measured, the average value of the volume is calculated, and B / A is obtained.

  When a concavo-convex surface having a B / A exceeding 6.5 is formed, the degree of minute undulations on the surface of the resin coating layer increases, and the concavo-convex shape also increases non-uniformity. In particular, when an elastic blade and toner having a high sphericity are used, toner fusion tends to occur starting from uneven unevenness, and image streaks and image density unevenness may occur.

  When B / A is less than 4.5, the number of minute uneven surfaces becomes too small, the releasability from the toner surface is lowered, and the chance of contact between the graphitized particles and the toner particles is reduced. Sleeve ghost and toner contamination are likely to occur due to up.

  In order to control the B / A indicating the degree of minute unevenness in the region where the roughened particles do not form protrusions on the surface of the resin coating layer between 4.5 and 6.5, graphitized particles It is preferable to adjust the dispersion state and coating method in the resin coating layer.

  As a method for controlling B / A depending on the dispersion state of the graphitized particles, it is preferable to disperse the graphitized particles in the resin coating layer so that the volume average particle diameter is 0.5 to 4.0 μm. When the volume average particle size is less than 0.5 μm, it becomes difficult to form a fine uneven surface with graphitized particles on the resin coating layer, and B / A tends to be less than 4.5. On the other hand, if the volume average particle size exceeds 4.0 μm, the unevenness imparted to the surface of the resin coating layer by the graphitized particles becomes too large, and B / A tends to exceed 6.5.

  The graphitized particles dispersed in the resin coating layer preferably have 5% by volume or less, more preferably 2% by volume or less of particles having a particle size of 10 μm or more in the volume distribution. When the particle size of 10 μm or more exceeds 5% by volume, uneven unevenness due to graphitized particles tends to occur on the surface of the resin coating layer, and B / A tends to exceed 6.5.

  Control of the volume average particle diameter of the graphitized particles in the resin coating layer is performed by adjusting the particle size distribution of the graphitized particles used by pulverization or classification, and adjusting the dispersion strength of the graphitized particles in the resin coating layer. Is possible.

  The particle size of the conductive particles such as graphitized particles is measured using, for example, a Coulter LS-230 type particle size distribution meter (manufactured by Coulter, Inc.) of a laser diffraction type particle size distribution meter. As a measuring method, a small amount module is used, and isopropyl alcohol (IPA) is used as a measuring solvent. Wash the measurement system of the particle size distribution analyzer with IPA for about 5 minutes, and execute the background function after washing.

  Next, 1 to 25 mg of a measurement sample is added to 50 ml of IPA. The solution in which the sample is suspended is subjected to a dispersion treatment for about 1 to 3 minutes with an ultrasonic disperser to obtain a sample solution. The sample solution is gradually added into the measurement system of the measurement device, and the PIDS on the screen of the device is 45. Measurement is performed by adjusting the sample concentration in the measurement system so as to be ˜55%, and the volume average particle diameter calculated from the volume distribution is obtained.

  On the other hand, as a method for controlling B / A by the coating method, although it varies depending on the prescription and characteristics of the resin coating layer to be used, it is generally easy to adjust B / A to be larger when using air spray coating, When dip coating is used, B / A can be controlled to be small.

  The developer carrying member of the present invention preferably has an arithmetic average roughness Ra (hereinafter referred to as “Ra”) of the resin coating layer surface of 0.9 to 2.5 μm, and preferably 1.0 to 2 More preferably, it is 0.0 μm.

  When Ra is less than 0.9 μm, particularly when an elastic blade and toner having a high sphericity are used, toner fusion and charge-up are likely to occur, resulting in lower image density, image streaks, and image density unevenness. And sleeve ghosting may occur.

  When Ra exceeds 2.5 μm, the amount of toner transported on the developer bearing member becomes too large, and it becomes difficult to uniformly apply frictional charge to the toner, and fog and sleeve ghost are likely to occur.

  The measurement of the arithmetic mean roughness (Ra) of the surface of the developer carrier is based on the surface roughness of JIS B0601, for example, using a surf coder SE-3500 manufactured by Kosaka Laboratories, with a cutoff of 0.8 mm. Then, at an evaluation length of 4 mm and a feed rate of 0.5 mm / s, each of 3 points in the axial direction × 3 points in the circumferential direction = 9 points is measured, and the average value is obtained.

  In order to control Ra of the developer carrying member to 0.9 to 2.5 μm, it is preferable to select the volume average particle diameter of the rough particles used in the resin coating layer as follows.

The crude was particles used in the present invention, the volume average particle diameter of 8.7 to 18.8 [mu] m. When the volume average particle diameter of the roughened particles is less than 5.5 μm, it is necessary to add a large amount of roughened particles to the resin coating layer in order to adjust the Ra of the surface of the resin coating layer to 0.9 or more. Graphitized particles on the surface of the resin coating layer are relatively reduced, and the lubricity and chargeability of the resin coating layer are likely to be impaired.

  When the volume average particle diameter of the roughened particles exceeds 20 μm, the surface roughness of the resin coating layer tends to be non-uniform, Ra is difficult to control to 2.5 or less, and the triboelectric charging of the toner is slowed down. Uniform and sufficient toner frictional charging is difficult to occur, fog is likely to occur, and negative sleeve ghost is likely to occur. Further, when an elastic blade is used, scratches are likely to occur on the coating blade due to the uneven convex shape on the surface of the resin coating layer.

  The measurement of the volume average particle diameter of the coarse particles is performed in the same manner as the measurement of the graphitized particles.

  The developer-carrying member of the present invention can be used by further dispersing lubricant particles in the resin coating layer. Examples of the lubricating particles include graphite, molybdenum disulfide, boron nitride, mica, graphite fluoride, silver-niobium selenide, calcium chloride-graphite, talc, and fatty acid metal salts (such as zinc stearate). The volume average particle diameter of these lubricating particles in the coating resin phase is preferably 0.5 to 4.0 μm for the same reason as the graphitized particles.

In the present invention, the volume resistance of the resin coating layer of the developer carrying member is preferably 10 ⁻² to 10 ⁵ Ω · cm, more preferably 10 ⁻² to 10 ³ Ω · cm. When the volume resistance of the resin coating layer exceeds 10 ⁵ Ω · cm, the toner is likely to be charged up and toner contamination on the surface of the resin coating layer is likely to occur.

  The volume resistance of the resin coating layer is measured by forming a 7 to 20 μm resin coating layer on a 100 μm thick polyethylene terephthalate (PET) sheet, and measuring the resistivity meter Loresta AP or Hiresta IP (both manufactured by Mitsubishi Chemical). The volume resistance value is measured using a four-terminal probe. The measurement environment is a temperature of 20 to 25 ° C. and a humidity of 50 to 60% RH.

  In the present invention, in order to adjust the volume resistance of the resin coating layer to the above value, other conductive fine particles may be dispersed in the resin coating layer in combination with graphitized particles.

  The conductive fine particles preferably have a number average particle diameter of preferably 1.00 μm or less, more preferably 0.01 to 0.80 μm. When the number average particle diameter of the conductive fine particles dispersed and contained in combination with the graphitized particles in the resin coating layer exceeds 1.00 μm, it becomes difficult to uniformly control the volume resistance of the resin coating layer, Uniform frictional charging is difficult.

  Examples of the conductive fine particles that can be used in the present invention include carbon black such as furnace black, lamp black, thermal black, acetylene black, and channel black; titanium oxide, tin oxide, zinc oxide, molybdenum oxide, potassium titanate, oxidation Fine particles of metal oxides such as antimony and indium oxide; fine particles of metals such as aluminum, copper, silver and nickel; graphite. In some cases, metal fibers or carbon fibers may be used.

  The content of the conductive fine particles contained in the resin coating layer together with the graphitized particles is preferably 40 parts by mass or less, more preferably 2 to 35 parts by mass with respect to 100 parts by mass of the coating resin. Such a content is preferable because the volume resistance can be adjusted to the desired value as described above without impairing other physical properties required for the resin coating layer.

  When the content of the conductive fine particles exceeds 40 parts by mass, a decrease in the strength of the resin coating layer is observed, which is not preferable.

  As the coating resin for the resin coating layer constituting the developer carrying member of the present invention, a known resin that has been conventionally used for the resin coating layer of the developer carrying member can be used. For example, thermoplastic resins such as styrene resins, vinyl resins, polyethersulfone resins, polycarbonate resins, polyphenylene oxide resins, polyamide resins, fluororesins, fiber resins, acrylic resins, epoxy resins, polyester resins, alkyd resins , Phenol resin, melamine resin, polyurethane resin, urea resin, silicone resin, polyimide resin. Among them, those with releasability such as silicone resin and fluororesin, or excellent mechanical properties such as polyethersulfone, polycarbonate, polyphenylene oxide, polyamide, phenol, polyester, polyurethane, styrene resin, acrylic resin Is more preferable. More preferably, a thermosetting resin or a photocurable resin is used.

  In the present invention, in order to adjust the chargeability of the developer carrying member, a charge control agent may be contained in the resin coating layer in combination with the graphitized particles. In that case, it is preferable that content of a charge control agent shall be 1-100 mass parts with respect to 100 mass parts of coating resin. If it is less than 1 part by mass, the effect of charge control by addition is low, and if it exceeds 100 parts by mass, poor dispersion occurs in the resin coating layer and the film strength tends to decrease.

  As the charge control agent, nigrosine, a modified product of nigrosine modified with a fatty acid metal salt; a quaternary ammonium salt such as tributylbenzylammonium-1-hydroxy-4-naphthosulfonate, tetrabutylammonium tetrafluoroborate; tributylbenzyl Phosphonium salts such as phosphonium-1-hydroxy-4-naphthosulfonate, tetrabutylphosphonium tetrafluoroborate; lake pigments thereof (phosphorungstic acid, phosphomolybdic acid, phosphotungsten molybdic acid, tannic acid , Lauric acid, gallic acid, ferricyanide, ferrocyanide, etc.), metal salts of higher fatty acids; diorganotin oxides such as butyltin oxide, dioctyltin oxide, dicyclohexyltin oxide ; Ji butyl tin borate, dioctyl tin borate, such as dicyclohexyl tin borate diorgano tin borate such; guanidines, imidazole compounds.

  Among these charge control agents, when using a negative toner having a particularly high spheroidization degree, a quaternary ammonium salt compound that is positively charged with respect to iron powder may be included in the resin coating layer as the charge control agent. From the viewpoint of improving the good charge imparting property to the toner of the present invention. The resin coating layer has at least one of an amino group, ═NH group, and —NH— bond in the resin structure, from the viewpoint of good charge imparting property to the negative toner having a high sphericity used in the present invention. Further preferred.

  By providing a resin coating layer that combines a quaternary ammonium salt compound and a coating resin on the substrate of the developer carrier, it works to prevent excessive charging of the negative toner with a high degree of spheroidization, and imparts triboelectric charging to the negative toner. Can be controlled. This prevents toner charge-up on the developer carrier, prevents toner fusion on the surface of the resin coating layer, and maintains high toner charging stability, resulting in environmental stability and long-term stability. It is possible to provide a high-definition image having

  The reason is not clear, but it is presumed as follows. When added to the resin coating layer, the quaternary ammonium salt compound that is positively charged with respect to the iron powder suitably used in the present invention has an amino group, ═NH group or —NH— group in the molecular chain. It is considered that the resin composition itself having a quaternary ammonium salt compound is negatively charged when uniformly formed in a resin having at least one of the following. Therefore, for negatively chargeable toners, the toner acts in a direction that prevents the toner from having an excessively negative charge amount, and as a result, the negative charge amount of the toner can be appropriately controlled.

  As the quaternary ammonium salt compound having the above-mentioned function that is preferably used in the present invention, any compound may be used as long as it has a positive chargeability with respect to iron powder. Examples of the quaternary ammonium salt compound include compounds represented by the following general formula.

(In the formula, R ₁ , R ₂ , R ₃ and R ₄ may be the same or different, and may be an alkyl group which may have a substituent, an aryl group or an alkyl which may have a substituent. Represents an alkyl group, and X ⁻ represents an anion of an acid.)
In the general formula, X ^- as the acid ion, organic sulfate ion, organic sulfonate ion, organic phosphate ion, molybdate ion, tungstate ion, and a heteropoly acid containing molybdenum atoms or tungsten atoms.

  Specific examples of the quaternary ammonium salt compound that is preferably positively charged with respect to the iron powder used in the present invention include the following, but the present invention is not limited thereto. It is not something.

  Phenol produced using a nitrogen-containing compound as a catalyst in the production process as a preferred resin containing at least one of an amino group, ═NH group or —NH— group in the molecular chain in combination with a quaternary ammonium salt Examples thereof include resins, polyamide resins, epoxy resins using polyamide as a curing agent, urethane resins, and copolymers partially containing these resins. The quaternary ammonium salt compound is dispersed in the coating resin during film formation of the mixture with these coating resins.

  In the present invention, as a phenol resin that can be suitably used in combination with a quaternary ammonium salt, as a nitrogen-containing compound used as an acidic catalyst in the phenol resin production process, ammonium sulfate, ammonium phosphate, ammonium sulfamate, Examples thereof include ammonium salts and amine salts such as ammonium carbonate, ammonium acetate, and ammonium maleate. Nitrogen-containing compounds used as basic catalysts in the phenol resin production process include ammonia; dimethylamine, diethylamine, diisopropylamine, diisobutylamine, diamylamine, trimethylamine, triethylamine, tri-n-butylamine, triamylamine, dimethylbenzylamine. , Diethylbenzylamine, dimethylaniline, diethylaniline, N, N-di-n-butylaniline, N, N-diamilaniline, N, N-di-t-amylaniline, N-methylethanolamine, N-ethylethanolamine , Diethanolamine, triethanolamine, dimethylethanolamine, diethylethanolamine, ethyldiethanolamine, n-butyldiethanolamine, di-n-butylethanolamine, Amino compounds such as lysopropanolamine, ethylenediamine, hexamethylenetetramine; pyridine; derivatives of pyridine such as α-picoline, β-picoline, γ-picoline, 2,4-lutidine, 2,6-lutidine; quinoline compounds; imidazole; Derivatives of imidazoles such as 2-methylimidazole, 2,4-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 2-heptadecylimidazole; nitrogen-containing heterocycles And formula compounds.

  Further, as the polyamide resin constituting the coating resin suitably used in the present invention, nylon 6, 66, 610, 11, 12, 9, 13, Q2 nylon, a nylon copolymer mainly composed of these, N -Alkyl-modified nylon or N-alkoxylalkyl-modified nylon can be preferably used. Further, various resins modified with polyamide such as polyamide-modified phenol resin, or resins containing a polyamide resin such as an epoxy resin using a polyamide resin as a curing agent can be used.

  As a coating resin suitably used in combination with a quaternary ammonium salt, a urethane resin having a urethane bond can be used. The urethane bond is obtained by polymerization addition reaction of polyisocyanate and polyol. Polyisocyanates that are the main raw materials for polyurethane resins include TDI (tolylene diisocyanate), pure MDI (diphenylmethane diisocyanate), polymeric MDI (polymethylene polyphenyl polyisocyanate), TODI (tolidine diisocyanate), and NDI (naphthalene diisocyanate). Aromatic polyisocyanates; aliphatic systems such as HMDI (hexamethylene diisocyanate), IPDI (isophorone diisocyanate), XDI (xylylene diisocyanate), hydrogenated XDI (hydrogenated xylylene diisocyanate), hydrogenated MDI (dicyclohexylmethane diisocyanate) A polyisocyanate is mentioned.

  Polyols that are the main raw materials for polyurethane resins include polyether polyols such as polyoxypropylene glycol (PPG), polymer polyols, and polytetramethylene glycol (PTMG); polyester polyols such as adipate, polycaprolactone, and polycarbonate polyols; PHD Polyether-based modified polyols such as polyols and polyether ester polyols; epoxy-modified polyols; partially saponified polyols of ethylene-vinyl acetate copolymers (saponified EVA); flame retardant polyols.

  Next, the configuration of the developer carrying member of the present invention will be described. The developer carrier of the present invention has a base and a resin coating layer formed on the surface of the base.

  Examples of the shape of the substrate include a cylindrical member, a columnar member, and a belt-like member. When a non-contact developing method is used for the photosensitive drum, a metal cylindrical member is preferably used. Specifically, a metal cylindrical tube is preferably used. As the metal cylindrical tube, nonmagnetic stainless steel, nonmagnetic aluminum, and a nonmagnetic alloy thereof are preferably used.

  In addition, as a substrate in the case of using a developing method that directly contacts a photosensitive drum, a metal cored bar having a layer containing a rubber such as urethane rubber, EPDM rubber, or silicone rubber, a urethane elastomer, an EPDM elastomer, or a silicone elastomer A columnar member is preferably used. In the developing method using a magnetic developer, a magnet roller having a magnet is disposed in the developer carrying body in order to magnetically attract and hold the magnetic developer on the developer carrying body. In that case, the base body is cylindrical and a magnet roller is disposed therein.

  Hereinafter, the structure of the resin coating layer in the developer carrier of the present invention will be described. FIG. 1 is a schematic cross-sectional view showing a part of the developer carrying member of the present invention. In FIG. 1, a resin coating layer 17 in which graphitized particles a and rough particles b having a specific degree of graphitization are dispersed in a coating resin c is laminated on a base 16 formed of a metal cylindrical tube. ing.

  In FIG. 1, since the graphitized particles b are uniformly and finely dispersed in the coating resin c on the surface of the resin coating layer 17 where there are no convex portions imparted to the rough particles a, Minute irregularities are formed. For this reason, the surface of the resin coating layer in which minute irregularities are formed by the graphitized particles b is good due to the increased contact area between the toner releasability and the toner particle surface resulting from the minute irregularities. It is easy to obtain a good chargeability, and it has a structure in which the lubricity, conductivity and chargeability due to the graphitized particles themselves are more easily exhibited, and there are few uneven irregularities formed by the graphitized particles. The toner is less likely to fuse and the toner is easily and quickly charged.

  On the other hand, the roughened particles a have a shape close to a sphere, and have a convex height and number so that the arithmetic average roughness Ra of the surface of the resin coating layer is 0.9 to 2.5. Yes. This convexity improves the toner transportability on the resin coating layer and the wear resistance of the surface of the resin coating layer, reduces the mechanical deterioration of the toner due to the toner regulating member, and stabilizes the charging of the toner. Toner fusion is less likely to occur.

  Next, the composition ratio of each component constituting the resin coating layer will be described. This composition ratio is a particularly preferable range in the present invention, but the present invention is not limited to this.

  The content of the graphitized particles dispersed in the resin coating layer is preferably 30 to 160 parts by mass, more preferably 50 to 130 parts by mass with respect to 100 parts by mass of the coating resin. The effect of maintaining the surface shape, imparting electrification to the toner, and preventing toner fusion is more exhibited. When the content of graphitized particles is less than 30 parts by mass, the effect of adding graphitized particles is small, and when it exceeds 160 parts by mass, the adhesiveness of the resin coating layer becomes too low and wear resistance decreases. May end up.

  The content of the rough particles contained in the resin coating layer together with the graphitized particles is preferably 2 to 60 parts by mass, more preferably 2 to 50 parts by mass with respect to 100 parts by mass of the coating resin. As a result, particularly preferable results are obtained in terms of formation and maintenance of Ra of the resin coating layer and prevention of toner contamination and toner fusion. When the content of the rough particles is less than 2 parts by mass, the effect of adding the coarse particles is small, and when it exceeds 60 parts by mass, the lubricity and chargeability of the resin coating layer surface may be impaired. is there.

The layer thickness of the resin coating layer is preferably 25 μm or less, more preferably 20 μm or less, and further preferably 4 to 20 μm in order to obtain a uniform film thickness, but is not limited to this layer thickness. . Although these layer thicknesses depend on the material used for the resin coating layer, they can be obtained by adhering to the substrate surface in an amount of 4000 to 20000 mg / m ^{2 in} solid content.

  Next, the toner used for the developer carrying member of the present invention will be described.

  The toner particles used in the present invention have an average circularity of 0.935 or more and less than 0.970, preferably 0.935 or more and less than 0.965, more preferably 0.935 or more and 0.0. It is preferably less than 960, more preferably 0.940 or more and less than 0.955. When the average circularity of the toner particles is within the above range, the fluidity of the toner is increased, so that individual toners can move freely, are easily and quickly triboelectrically charged, and can be developed with each toner. Therefore, the height of the toner on the photosensitive drum and the transfer material is reduced, and a sufficient image density can be obtained even if the amount of toner used is small.

  At this time, if the average circularity of the toner particles is not high, the toner tends to behave as an aggregate, the toner aggregate forms a toner image on the photosensitive drum, and the toner image is further transferred onto the transfer material. Is done. In such a toner image, the height of the toner image on the transfer material becomes high, and when developing the same area, more toner is developed than toner having excellent fluidity, and the amount of toner consumption increases. . In addition, a toner having toner particles having a high average circularity tends to take a denser state in a developed toner image. As a result, the toner concealment ratio with respect to the transfer material is increased, and a sufficient image density can be obtained even with a small amount of toner. When the average circularity is less than 0.935, the height of the developed toner image tends to be high, and the toner consumption increases. In addition, voids between toner particles are increased, and a developed toner image cannot obtain a sufficient concealment ratio. Therefore, a larger amount of toner is required to obtain a necessary image density, resulting in toner consumption. Will increase the amount. If the average circularity is 0.970 or more, the developability tends to deteriorate during long-term use of the toner.

The average circularity is used as a simple method for quantitatively expressing the particle shape. In the present invention, the flow type particle image analyzer FPIA-2100 manufactured by Sysmex Corporation is used and the temperature is 23 ° C. and the humidity is 60% RH. And measure the particles in the range of the equivalent circle diameter of 0.60 μm to 400 μm. The circularity of the particles measured there is expressed by the following equation (3)
Circularity a = L ₀ / L (3)
[Where L ₀ represents the circumference of a circle having the same projection area as the particle image, and L represents the particle projection when image processing is performed at an image processing resolution of 512 × 512 (pixels of 0.3 μm × 0.3 μm). Indicates the perimeter of the image. ]
Further, for particles having an equivalent circle diameter of 3 μm or more and 400 μm or less, a value obtained by dividing the total circularity by the total number of particles is defined as the average circularity.

  The average circularity used in the present invention is an index of the degree of unevenness of the toner particles. The average circularity is 1.00 when the toner is perfectly spherical, and the average circularity becomes smaller as the surface shape becomes more complicated. “FPIA-2100”, which is a measuring apparatus used in the present invention, calculates the circularity of each particle, and then calculates the average circularity. A calculation method is used in which 0 is divided into 61 classes, and the average circularity is calculated using the center value and frequency of the division points. However, the error of the average circularity calculated by the calculation formula using the value of the average circularity calculated by this calculation method and the total circularity of each particle is very small and can be substantially ignored. In the present invention, for the reason of handling data such as shortening the calculation time and simplifying the calculation operation formula, the concept of the calculation formula using the sum of the circularity of each particle is used and partly changed. Such a calculation method is used. Furthermore, the measurement device used in the present invention, “FPIA-2100”, improves the processing particle image magnification and captures more than “FPIA1000”, which has been used to calculate the shape of the toner. The accuracy of toner shape measurement is improved by improving the processing resolution of the image (256 × 256 → 512 × 512). Therefore, when it is necessary to measure the shape and particle size distribution more accurately as in the present invention, the FPIA 2100 that can obtain information on the shape and particle size distribution more accurately is useful.

As a specific measuring method, 0.1 to 0.5 ml of a surfactant (preferably alkylbenzene sulfonate) is added as a dispersant to 200 to 300 ml of water from which impurities in the container have been removed in advance, and a measurement sample is further added. Add about 0.1-0.5g. The suspension in which the sample is dispersed is dispersed with an ultrasonic oscillator for 2 minutes, and the circularity distribution of the particles is measured at a dispersion concentration of 0.2 to 1 million particles / μl. As the ultrasonic oscillator, for example, the following apparatus is used, and the following dispersion conditions are used.
Device UH-150 (manufactured by SMT Corporation)
Distribution condition OUTPUT level: 5
The outline of constant mode measurement is as follows.

  The sample dispersion is passed through a flow channel (spread along the flow direction) of a flat and flat flow cell (thickness: about 200 μm). The strobe and the CCD camera are mounted on the flow cell so as to be opposite to each other so as to form an optical path that passes through the thickness of the flow cell. While the sample dispersion is flowing, strobe light is irradiated at 1/30 second intervals to obtain an image of the particles flowing through the flow cell, so that each particle has a certain range parallel to the flow cell. Photographed as a two-dimensional image. From the area of the two-dimensional image of each particle, the diameter of a circle having the same area is calculated as the equivalent circle diameter. The circularity of each particle is calculated from the projected area of the two-dimensional image of each particle and the perimeter of the projected image using the above circularity calculation formula.

  In the present invention, the toner particle ratio of 0.6 to 3 μm in the number average particle size distribution measured by the flow type particle image measuring device is 0 to 20%, preferably 0 to 17%. It is preferably less than number%, more preferably 1% or more and less than 15%. Toner particles having a size of 0.6 μm or more and less than 3 μm have a great influence on the developability of the toner, particularly the fog characteristics. Such a fine particle toner has an excessively high triboelectric chargeability, and the fine particle toner in the toner is charged up, so that the toner is easily fogged at the time of developing the toner. It becomes easy to fuse to the body surface. In the present invention, fog and toner fusion can be reduced by such a small proportion of the fine particle toner.

  Toner with a high average circularity tends to be more densely packed with toner, so the toner is coated thicker on the developing sleeve. As a result, the charge amount is different between the upper and lower layers of the toner layer on the sleeve, and the continuous As a result, when a large area image is developed, a sleeve negative ghost in which the image density of the second and subsequent sleeves is lower than the image density of the leading edge may occur. If a large amount of ultrafine powder is present in the toner at this time, the superfine powder has a higher charge amount than the other toner particles, so that the sleeve negative ghost is deteriorated. In the present invention, since the amount of ultrafine powder is small, deterioration of the sleeve negative ghost can be suppressed. When the particle ratio of 0.6 μm or more and less than 3 μm is 20% by number or more, fogging on the image tends to increase and sleeve negative ghost tends to deteriorate. The toner particles in the toner used in the present invention have a cumulative number of toner particles having a circularity of less than 0.960 of 20% to less than 70%, preferably 25% to less than 65%. Is preferably 30% or more and less than 65%, more preferably 35% or more and less than 65%. The circularity of the toner particles varies depending on the individual toner particles. When the degree of circularity is different, the characteristics as toner particles are also different. Therefore, it is preferable that the ratio of toner particles having an appropriate degree of circularity is an appropriate value in order to improve the developability of the toner. The toner particles in the toner used in the present invention have an appropriate degree of circularity, and since the toner has an appropriate degree of circularity distribution, the toner charge distribution becomes uniform and fogging can be reduced. it can. If the cumulative number of toner particles having a circularity of less than 0.960 is less than 20% by number, the toner particles may deteriorate during durability. If the cumulative value of the number of toner particles having a circularity of less than 0.960 is 70% by number or more, the fog may be deteriorated or the image density may be lowered in a high temperature and high humidity environment.

  In the present invention, the average surface roughness of the toner particles may be 5.0 nm or more and less than 35.0 nm, preferably 8.0 nm or more and less than 30.0 nm, more preferably 10.0 nm or more and less than 25.0 nm. preferable. When the toner particles have an appropriate surface roughness, appropriate voids are created between the toner particles, the fluidity of the toner can be improved, and better developability can be provided. The toner particles contained in the toner having a specific average circularity used in the present invention can impart excellent fluidity to the toner by having a specific average surface roughness. Further, the toner used in the present invention has a small amount of ultrafine particles of less than 3 μm, which effectively works to improve fluidity. When a large amount of ultrafine particles are present in the toner, the ultrafine particles enter the concave portions on the surface of the toner particles, apparently reducing the average surface roughness of the toner particles, reducing the voids between the toner particles, and being preferable to the toner. This impedes imparting fluidity. When the average surface roughness of the toner particles is less than 5.0 nm, it is difficult to impart sufficient fluidity to the toner, fading occurs, and the image density decreases. When the average surface roughness of the toner particles is 35.0 nm or more, the toner particles are likely to be scattered due to excessive voids between the toner particles.

In the present invention, the average surface roughness of the toner particles is measured using a scanning probe microscope. Below, the example of a measuring method is shown.
Prose Station: SPI3800N (manufactured by Seiko Instruments Inc.)
Measuring unit: SPA400
Measurement mode: DFM (resonance mode) shape image Cantilever: SI-DF40P
Resolution: Number of X data 256
Number of Y data 128
In the present invention, an area of 1 μm square on the surface of the toner particles is measured. As the toner particles to be measured, toner particles equal to the weight average particle diameter (D ₄ ) measured by the Coulter counter method are randomly selected, and the toner particles are measured. The measured data is subjected to secondary correction. Five or more different toner particles are measured, and the average value of the obtained data is calculated to obtain the average surface roughness of the toner particles. Each term is explained below.
Average surface roughness (Ra)
The arithmetic average roughness Ra defined in JIS B0601 is extended to three dimensions so that it can be applied to the measurement surface. The absolute value of the deviation from the reference plane to the specified plane is averaged and expressed by the following formula.

F (X, Y): Surface S ₀ indicated by all measurement data: Area when assuming that the designated surface is ideally flat Z ₀ : Average value of Z data in the designated surface The designated surface is the present invention. Means a measurement area of 1 μm square.

  Next, as a preferable method for obtaining the toner particles used in the present invention, a method for producing toner particles using a surface modification step will be described. Hereinafter, a surface modifying device used in the surface modifying step and a toner particle manufacturing method using the surface modifying device will be specifically described with reference to the drawings.

  FIG. 2 shows an example of a surface modification device for toner particles, and FIG. 3 shows an example of a top view of a rotor (dispersing rotor) that rotates at a high speed in FIG.

  The surface reforming apparatus shown in FIG. 2 having the dispersion rotor 36 shown in FIG. 3 has a casing, a jacket (not shown) through which cooling water or antifreeze liquid can flow, and is attached to the central rotating shaft in the casing. The dispersion rotor (surface modification means) 36, which is a rotating body on a disk that has a plurality of square disks 40 or cylindrical pins 40 on the upper surface and rotates at a high speed, has a constant interval on the outer periphery of the dispersion rotor 36. A liner 34 having a large number of grooves on the surface that is held and arranged (there is no need to have grooves on the liner surface), and for classifying the surface-modified raw material into a predetermined particle size Classifying rotor 31 as a means, a cold air introduction port 35 for introducing cold air, a raw material supply port 33 for introducing a raw material to be treated, and opening and closing so that the surface modification time can be freely adjusted. OK A discharge valve 38, a powder discharge port 37 for discharging processed powder (toner particles), a classification rotor 31, and a space between the dispersion rotor 36 and the liner 34, A partition guide for forming a first space 41 for introducing the material to be treated into the classification means and a second space 42 for introducing the particles from which fine powder has been classified and removed by the classification rotor into the surface modification zone. It comprises a cylindrical guide ring 39 as means. A gap portion between the dispersion rotor 36 and the liner 34 is a surface modification zone, and a classification rotor 31 and a peripheral portion of the classification rotor are classification zones.

  The orientation of the classification rotor 31 may be vertical as shown in FIG. 2 or horizontal. The number of classification rotors 31 may be single as shown in FIG. 2 or plural.

  In the surface reforming apparatus, when raw material particles are introduced from the raw material supply port 33 with the discharge valve 38 closed, the charged raw material particles are sucked by a blower (not shown) and classified by the classification rotor 31. . At that time, the classified fine powder having a predetermined particle diameter or less is continuously discharged and removed out of the apparatus, and the coarse powder having a predetermined particle diameter or more passes along the inner periphery (second space 42) of the guide ring 39 by centrifugal force. The circulating flow generated by the dispersion rotor 36 is guided to the surface modification zone. The raw material particles guided to the surface modification zone are subjected to a surface modification treatment by receiving a mechanical impact force between the dispersion rotor 36 and the liner 34. The surface-modified particles having undergone surface modification are guided to the classification zone along the outer periphery (first space 41) of the guide ring 39 along the cold air passing through the inside of the apparatus. The coarse powder discharged to the outside of the machine is put into a circulating flow, returned to the surface modification zone again, and repeatedly subjected to the surface modification action. After a certain period of time, the discharge valve 38 is opened, and the surface modified particles (toner particles) are collected from the discharge port 37.

  In the toner particle surface modifying step using the surface modifying apparatus, the fine powder component can be removed simultaneously with the toner particle surface modification. As a result, the ultrafine particles present in the toner do not adhere to the surface of the toner particles, and toner particles having a desired circularity, average surface roughness, and ultrafine particle amount can be obtained effectively. On the other hand, when the fine powder cannot be removed simultaneously with the surface modification, the amount of ultrafine particles in the toner after the surface modification is large, and in the surface modification process of the toner particles, mechanical and thermal For this reason, the ultrafine particle component adheres to the surface of the toner particles having an appropriate particle size. As a result, protrusions due to the adhering fine powder component are generated on the surface of the toner particles, and it is difficult to obtain toner particles having a desired circularity and average surface roughness.

  As a method for producing toner particles, raw toner particles that have been finely divided in the vicinity of a desired particle diameter are removed to some extent by using an airflow classifier, and then the toner particles are separated by a surface modification device. It is preferable to perform surface modification and removal of ultrafine powder components. By removing the fine powder in advance, the dispersion of the toner particles in the surface modifying apparatus becomes good. In particular, toner particles having a particle size of 0.6 μm or more and less than 3 μm have a large specific surface area and a relatively high triboelectric charge amount compared to other large toner particles, so that the ultrafine powder component is not easily separated from the toner particles. The ultra fine powder component may not be properly classified by the rotor. By removing the fine powder component in the toner particle raw material in advance, the individual toner particles are easily dispersed in the surface modifying device, and the ultra fine powder component is appropriately classified by the classification rotor and has a desired particle size distribution. Toner can be obtained. In the toner from which fine powder has been removed by an airflow classifier, the cumulative value of the number average distribution of toner particles having a particle diameter of less than 4 μm is 10% by number or more and less than 50% by number in a particle size distribution measured using a Coulter counter method. The content is preferably 15% by number or more and less than 45% by number, more preferably 15% by number or more and less than 40% by number, and the ultrafine powder component can be effectively removed by the surface modifying apparatus. As an airflow classifier used in the present invention, an elbow jet (manufactured by Nippon Steel Industries Co., Ltd.) can be mentioned.

  In the present invention, by controlling the number of revolutions of the dispersion rotor and the classification rotor in the surface modifying apparatus, the particle ratio of 0.6 μm or more and less than 3 μm in the toner can be controlled to a more appropriate value.

  The types of binder resins used in the toner used in the present invention include styrene resins, styrene copolymer resins, polyester resins, polyol resins, polyvinyl chloride resins, phenol resins, naturally modified phenol resins, and natural resin modified resins. Examples thereof include maleic acid resin, acrylic resin, methacrylic resin, polyvinyl acetate, silicone resin, polyurethane resin, polyamide resin, furan resin, epoxy resin, xylene resin, polyvinyl butyral, terpene resin, coumarone indene resin, and petroleum resin.

  The toner of the present invention preferably contains a charge control agent.

  Examples of the toner that controls the negative charge include the following compounds.

  For example, organometallic complexes and chelate compounds are effective, and there are monoazo metal complexes, acetylacetone metal complexes, aromatic hydroxycarboxylic acids, and aromatic dicarboxylic acid metal complexes. Others include aromatic hydroxycarboxylic acids, aromatic mono- and polycarboxylic acids and their metal salts, anhydrides, esters, and phenol derivatives such as bisphenol.

  The toner used in the present invention may contain a wax. The waxes used in the present invention include the following. For example, paraffin wax and derivatives thereof, montan wax and derivatives thereof, microcrystalline wax and derivatives thereof, Fischer-Tropsch wax and derivatives thereof, polyolefin wax and derivatives thereof, carnauba wax and derivatives thereof, and the like. Derivatives include oxides, block copolymers with vinyl monomers, and graft modified products.

  The toner used in the present invention is preferably a magnetic toner containing a magnetic material. The magnetic material can also serve as a colorant. Magnetic materials used in the toner include iron oxides such as magnetite, hematite and ferrite; metals such as iron, cobalt and nickel or these metals and aluminum, cobalt, copper, lead, magnesium, tin, zinc and antimony , Alloys with metals such as beryllium, bismuth, cadmium, calcium, manganese, selenium, titanium, tungsten, vanadium and mixtures thereof.

  Other colorants that can be used in the toner of the present invention include any suitable pigment or dye. Examples of the pigment include carbon black, aniline black, acetylene black, naphthol yellow, hansa yellow, rhodamine lake, alizarin lake, bengara, phthalocyanine blue, and indanthrene blue.

  The toner particles used in the present invention are preferably externally added with inorganic fine powder or hydrophobic inorganic fine powder. For example, silica fine powder, titanium oxide fine powder, or a hydrophobized product thereof can be used. They are preferably used alone or in combination.

  Silica fine powders include both dry silica produced by vapor phase oxidation of silicon halogen compounds or dry silica called fumed silica and wet silica produced from water glass. Dry silica with fewer silanol groups on the surface and inside and no production residue is preferred.

  Further, the silica fine powder is preferably hydrophobized. The hydrophobizing treatment is applied by chemically treating with an organosilicon compound that reacts or physically adsorbs with silica fine powder. Preferable methods include a method in which a dry silica fine powder produced by vapor phase oxidation of a silicon halogen compound is treated with a silane compound or with a silane compound and simultaneously with an organosilicon compound such as silicone oil.

  To the toner particles used in the present invention, additives other than silica fine powder or titanium oxide fine powder may be externally added as necessary.

  Examples thereof include resin fine particles and inorganic fine particles that act as charging aids, conductivity imparting agents, fluidity imparting agents, anti-caking agents, mold release agents during heat roll fixing, lubricants, and abrasives.

  The weight average particle diameter and particle size distribution of the toner are determined using a Coulter counter method. For example, Coulter Multisizer (manufactured by Coulter) can be used. As the electrolytic solution, a 1% NaCl aqueous solution is prepared using primary sodium chloride. For example, ISOTON R-II (manufactured by Coulter Scientific Japan) can be used. As a measurement method, 0.1 to 5 ml of a surfactant (preferably alkylbenzene sulfonate) is added as a dispersant to 100 to 150 ml of the electrolytic aqueous solution, and 2 to 20 mg of a measurement sample is further added. The electrolytic solution in which the sample is suspended is subjected to a dispersion treatment for about 1 to 3 minutes with an ultrasonic disperser, and the volume and number of toner particles of 2.00 μm or more are measured using the 100 μm aperture as the aperture by the measuring device. Volume distribution and number distribution are calculated. Then, the weight-based weight average particle diameter (D4) obtained from the volume distribution of the toner and toner particles is calculated. As channels, 2.00 to less than 2.52 μm; 2.52 to less than 3.17 μm; 3.17 to less than 4.00 μm; 4.00 to less than 5.04 μm; 5.04 to less than 6.35 μm; 6 Less than 35 to 8.00 μm; less than 8.00 to less than 10.08 μm; less than 10.08 to less than 12.70 μm; less than 12.70 to less than 16.00 μm; less than 16.00 to less than 20.20 μm; Use 13 channels less than 40 μm; 25.40 to less than 32.00 μm; 32.00 to less than 40.30 μm.

  A developing device having the developer carrying member of the present invention, an image forming apparatus having the developing device, and a process cartridge will be described. FIG. 4 is a schematic view showing an embodiment of a developing device having the developer carrying member of the present invention when a magnetic one-component developer is used as the developer. In FIG. 4, an electrophotographic photosensitive drum (electrophotographic photosensitive member) 1 as an electrostatic latent image carrier that holds an electrostatic latent image formed by a known process is rotated in the direction of arrow B.

  The developing sleeve 8 as a developer carrying member is disposed so as to face the electrophotographic photosensitive drum 1 with a predetermined gap. The developing sleeve 8 carries the one-component developer 4 having magnetic toner supplied by a hopper 3 as a developer container and rotates in the direction of arrow A, thereby facing the developing sleeve 8 on the surface of the photosensitive drum 1. The developer 4 is conveyed to the developing area D which is the closest part. As shown in FIG. 4, a magnet roller 5 containing a magnet is disposed in the developing sleeve 8 in order to magnetically attract and hold the developer 4 on the developing sleeve 8.

  The developing sleeve 8 of the present invention used in the developing device has a conductive resin coating layer 7 as a resin coating layer coated on a metal cylindrical tube 6 as a substrate. In the hopper 3, a stirring blade 10 for stirring the developer 4 is provided. A gap 12 indicates that the developing sleeve 8 and the magnet roller 5 are not in contact with each other.

  The developer 4 obtains a triboelectric charge capable of developing the electrostatic latent image on the photosensitive drum 1 by friction between the magnetic toners and the conductive resin coating layer 7 on the developing sleeve 8. In FIG. 5, in order to form a layer of the developer 4 conveyed to the development region D and regulate the layer thickness, the magnetic regulation blade 2 made of a ferromagnetic metal as a developer layer thickness regulating member is provided with a development sleeve 8. Is suspended from the hopper 3 so as to face the developing sleeve 8 with a gap width of about 50 to 500 μm from the surface of the toner. A magnetic force line from the magnetic pole N <b> 1 of the magnet roller 5 concentrates on the magnetic regulation blade 2, whereby a thin layer of the developer 4 is formed on the developing sleeve 8. In the present invention, a non-magnetic blade can be used instead of the magnetic regulating blade 2. The thickness of the thin layer of the developer 4 formed on the developing sleeve 8 in this manner is preferably thinner than the minimum gap between the developing sleeve 8 and the photosensitive drum 1 in the developing region D. .

  The developer carrying member of the present invention is particularly effective when incorporated in a non-contact type developing apparatus that develops an electrostatic latent image with a thin layer of the developer as described above. In the developing region D, the developer carrier of the present invention can also be applied to a contact-type developing device in which the thickness of the developer layer is equal to or greater than the minimum gap between the developing sleeve 8 and the photosensitive drum 1. Hereinafter, an example of a non-contact type developing device will be described.

  In order to cause the one-component developer 4 having magnetic toner carried on the developing sleeve 8 to fly, a developing bias voltage is applied to the developing sleeve 8 by a developing bias power source 9 as bias means. When a DC voltage is used as the developing bias voltage, a voltage having an intermediate value between the potential of the image portion of the electrostatic latent image (the region visualized with the developer 4 attached) and the potential of the background portion is applied to the developing sleeve 8. It is preferable to apply. In order to increase the density of the developed image or to improve the gradation, an alternating bias voltage may be applied to the developing sleeve 8 to form an oscillating electric field whose direction is alternately reversed in the developing region D. . In this case, it is preferable to apply to the developing sleeve 8 an alternating bias voltage in which a DC voltage component having an intermediate value between the potential of the developed image portion and the potential of the background portion is superimposed.

  In the case of regular development in which a toner image is formed by attaching toner to a high potential portion of an electrostatic latent image having a high potential portion and a low potential portion, toner charged to a polarity opposite to the polarity of the electrostatic latent image is used. use. In the case of reversal development in which a toner image is formed by attaching toner to a low potential portion of an electrostatic latent image having a high potential portion and a low potential portion, a toner charged with the same polarity as the polarity of the electrostatic latent image is used. use. High potential and low potential are expressions based on absolute values. In any of these cases, the developer 4 is charged at least by friction with the developing sleeve 8.

  FIG. 5 and FIG. 6 are schematic structural views showing other embodiments of the developing device of the present invention, respectively.

  5 and 6, the developer layer thickness regulating member for regulating the layer thickness of the developer 4 on the developing sleeve 8 is a material having rubber elasticity such as urethane rubber or silicone rubber, or phosphor bronze. An elastic regulating blade (elastic regulating member) 11 formed of an elastic plate made of a material having metal elasticity such as stainless steel is used. In the developing device of FIG. 5, the elastic regulating blade 11 is brought into pressure contact with the rotation direction of the developing sleeve 8 in the forward direction. In the developing device of FIG. The feature is that they are pressed in the opposite direction. In these developing devices, the developer layer thickness regulating member is elastically pressed against the developing sleeve 8 via the developer layer. As a result, a thin layer of developer is formed on the developing sleeve, so that a thinner developer layer can be formed on the developing sleeve 8 than when the magnetic regulation blade described with reference to FIG. 4 is used.

  5 and 6 are the same as those of the developing apparatus shown in FIG. 4, and the components having the same reference numerals basically indicate the same members.

  4 to 6 schematically illustrate the developing device of the present invention, and there are various variations in the shape of the developer container (hopper 3), the presence or absence of the stirring blade 10, the arrangement of the magnetic poles, and the like. Needless to say.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail using an Example and a comparative example, a present Example does not limit this invention at all. In the examples and comparative examples, “%” and “part” are all based on mass unless otherwise specified.

(Graphitized particle production example A-1)
As raw material for graphitized particles, β-resin is extracted from coal tar pitch by solvent fractionation, and the β-resin is hydrogenated by hydrogenation, and then the solvent-soluble component is removed with toluene to remove bulk mesophase. Got the pitch. The bulk mesophase pitch is finely pulverized, and the finely pulverized bulk mesophase pitch is oxidized at about 300 ° C. in air, followed by primary firing at 1200 ° C. in a nitrogen atmosphere, followed by carbonization, followed by a nitrogen atmosphere. Was graphitized by secondary firing at 3000 ° C. and further classified to obtain graphitized particles A-1 having a number average particle diameter of 3.1 μm. Table 1 shows the physical properties of the graphitized particles A-1.

(Graphitized particle production examples A-2 to 5)
Graphitized particles A-2 to A-5 were produced in the same manner as in the production example of graphitized particles A-1, except that the firing temperature and particle size of the bulk mesophase pitch of the raw material used were changed. Table 1 shows the physical properties of the obtained graphitized particles A-2 to A-5.

(Graphitized particle production example A-6)
As a raw material for graphitized particles, heat treatment is performed on heavy heavy coal oil, the resulting crude mesocarbon microbeads are centrifuged, the resulting crude mesocarbon microbeads are washed and purified with benzene, dried, and then atomized by an atomizer mill. Mesocarbon microbeads were obtained by mechanical dispersion. The mesocarbon microbeads are subjected to primary firing at 1200 ° C. in a nitrogen atmosphere and carbonized. The carbonized mesocarbon microbeads are secondarily dispersed by an atomizer mill, and then subjected to secondary firing at 2800 ° C. in a nitrogen atmosphere. Graphitized and further classified to obtain graphitized particles A-5 having a number average particle size of 3.4 μm. Table 1 shows the physical properties of the graphitized particles A-6.

(Graphitized particle production example A-7)
As a raw material for graphitized particles, a mixture of coke and tar pitch is used. This mixture is kneaded at a temperature equal to or higher than the softening point of tar pitch, extruded to form particles, and subjected to primary firing at 1000 ° C. in a nitrogen atmosphere. And then carbonized and subsequently impregnated with coal tar pitch, followed by secondary firing at 2800 ° C. in a nitrogen atmosphere, followed by graphitization, pulverization and classification, and graphitized particles A-7 having a number average particle size of 7.7 μm Got. Table 1 shows the physical properties of the graphitized particles A-7.

(Graphitized particle production examples A-8 to 9)
Graphitized particles A-8 to 9 were produced in the same manner as in the production example of graphitized particles A-1, except that the firing temperature and particle size of the bulk mesophase pitch of the raw material used were changed. Table 1 shows the physical properties of the graphitized particles A-8 to 9 obtained.

(Rough particle production example B-1)
100 parts of spherical phenolic resin particles having a volume average particle diameter of 13.5 μm are uniformly coated with 14 parts of a coal-based bulk mesophase pitch powder having a volume average particle diameter of 2 μm or less using a raikai machine (automatic mortar, manufactured by Ishikawa Factory), Heat-treated at 280 ° C. in air, calcined at 1900 ° C. in a nitrogen atmosphere, and further classified to obtain coarse particles B-1 made of spherical conductive carbon particles having a volume average diameter of 14.4 μm. It was. Table 2 shows the physical properties of the coarsened particles B-1.

(Roughened particle production example B-2 to 5)
Roughened particles B-2 to 5 were produced in the same manner as in the production example of the roughened particle B-1, except that the particle size of the spherical phenol resin particles used was changed. The physical properties of the obtained coarse particles B-2 to 5 are shown in Table 2, respectively.

(Preparation of paint intermediate C-1)
200 parts of a resol type phenolic resin solution produced using ammonia as a catalyst
(Containing 50% methanol)
Graphitized particles (A-1) 135 parts Isopropyl alcohol 200 parts To the above materials, zirconia beads having a diameter of 0.5 mm were added as media particles and dispersed in a horizontal sand mill to obtain paint intermediate C-1. As shown in Table 3, the graphitized particles A-1 dispersed in the coating intermediate C-1 were dispersed in a volume average particle size of 1.7 μm, and the volume cumulative distribution of 10 μm or more was 0%.

(Preparation of paint intermediates C-2 to 9)
Coating intermediates 2 to 9 were obtained in the same manner as coating intermediate C-1, except that graphitized particles A-2 to A-9 were used instead of graphitized particles A-1. Table 3 shows the composition of the coating intermediate and the volume particle size distribution.

(Preparation of developer carrier E-1)
100 parts of a resol type phenolic resin solution produced using ammonia as a catalyst
(Containing 50% methanol)
Conductive carbon black 15 parts Roughened particles B-1 22.5 parts Quaternary ammonium salt compound 20 parts Methanol 50 parts Add glass beads having a diameter of 1 mm to the above materials as media particles, and disperse the dispersion with a horizontal sand mill. Obtained.

  535 parts of paint intermediate C-1 was mixed with 207.5 parts of the above dispersion, and methanol was further added to obtain a coating liquid 1 having a solid content concentration of 32%.

  Using this coating solution 1, a resin coating layer is formed on a ground aluminum cylindrical tube having an outer diameter of 20 mmφ and an arithmetic average roughness Ra = 0.3 μm by an air spray method, followed by a hot air drying furnace at 150 ° C. The resin coating layer was cured by heating for 30 minutes to produce a developer carrier E-1. Table 4 shows the formulation and physical properties of the resin coating layer of the obtained developer carrying member E-1.

(Preparation of developer carrier E-2 to 3)
In the production of the developer carrier E-1, the developer carrier E-1 is the same as the developer carrier E-1, except that the addition amount of the rough particles B-1 is changed from 22.5 parts to 7.5 parts and 52 parts. Similarly, developer carriers E-2 and E-3 were produced. Table 4 shows the formulations and physical properties of the resin coating layers of the obtained developer carriers E-1 and E-3.

(Preparation of developer carrier E-4 to 5)
In the production of the developer carrier E-1, the developer carrier E-1 is the same as the developer carrier E-1, except that the coarse particles B-1 are changed to B-2 and B-3. -4 and E-5 were produced. Table 4 shows the formulations and physical properties of the resin coating layers of the obtained developer carriers E-4 and E-5.

(Preparation of developer carrier E-6-10)
Developer carrier E-6 was produced in the same manner as developer carrier E-1, except that paint intermediate C-1 was changed to C-2 to C-6 in the production of developer carrier E-1. To 10 were produced. Table 4 shows the formulation and physical properties of the resulting resin coating layer of the developer carrying member E-6-10.

(Preparation of developer carrier E-11)
In the production of developer carrier E-1, the same as developer carrier E-1, except that the solid content concentration of the coating liquid was 23% and coating was further performed using the dipping coating method. Thus, developer carrier E-11 was produced. Table 4 shows the formulation and physical properties of the resin coating layer of the resulting developer carrier E-11.

(Preparation of developer carrier E-12)
Developer carrier E-12 was produced in the same manner as developer carrier E-1, except that in the production of developer carrier E-1, rough particles B-1 were not added. Table 4 shows the formulation and physical properties of the resin coating layer of the resulting developer carrier E-12.

(Preparation of developer carrier E-13-14)
In the production of the developer carrier E-1, the developer carrier E-1 is the same as the developer carrier E-1, except that the coarse particles B-1 are changed to B-4 and B-5. -4 and E-5 were produced. Table 4 shows the formulations and physical properties of the resin coating layers of the obtained developer carriers E-13 and E-15.

(Preparation of developer carrier E-15-17)
In the production of the developer carrier E-1, the developer carrier E-15 is the same as the developer carrier E-1 except that the paint intermediate C-1 is changed to C-7 to C-9. ~ 17 were made. Table 4 shows the formulation and physical properties of the resin coating layer of the obtained developer carrier E-15-18.

(Preparation of developer carrier E-18)
In the production of developer carrier E-6, the same as developer carrier E-6 except that the solid content concentration of the coating liquid was 23% and coating was further performed using the dipping coating method. Thus, developer carrier E-18 was produced. Table 4 shows the formulation and physical properties of the resin coating layer of the resulting developer carrier E-18.

(Preparation of developer 1)
Styrene-butyl acrylate-acrylic acid copolymer 100 parts Magnetic body 95 parts Monoazo iron complex 2 parts Paraffin wax 4 parts The above mixture is premixed with a Henschel mixer and then melt kneaded with a biaxial extruder heated to 110 ° C. The cooled kneaded product was coarsely pulverized with a hammer mill to obtain a coarsely pulverized toner product. The obtained coarsely pulverized product was finely pulverized by mechanical pulverization using a mechanical pulverizer turbo mill (manufactured by Turbo Kogyo Co., Ltd .; coated with chromium alloy plating containing chromium carbide on the surface of the rotor and stator). The finely pulverized product obtained was classified and removed at the same time by a multi-division classifier (Elbow Jet Classifier manufactured by Nittetsu Mining Co., Ltd.) using the Coanda effect. The weight average particle diameter (D ₄ ) of raw material toner particles (medium powder) obtained by the Coulter counter method was 6.6 μm, and the cumulative value of the number average distribution of toner particles having a particle diameter of less than 4 μm was 25. 2% by number. The raw toner particles were subjected to surface modification and fine powder removal using the surface modification apparatus shown in FIG. Through the above steps, negatively chargeable toner particles having a cumulative value of the number average distribution of toner particles having a weight average particle diameter (D ₄ ) of 6.8 μm and less than 4 μm measured by the Coulter counter method are 18.1% by number. Obtained. The average circularity of 3 μm or more measured by FPIA2100 of this toner particle was 0.957, and the particle ratio of 0.6 μm or more and less than 3 μm was 16.8% by number. The average surface roughness of the toner particles measured using a scanning probe microscope was 13.5 nm.

  100 parts of the toner particles and 1.2 parts of hydrophobic silica fine powder treated with hexamethyldisilazane and then treated with dimethylsilicone oil were mixed with a Henschel mixer to prepare Developer 1.

(Examples 1-11, Comparative Examples 1-7)
Next, evaluation was performed by the following method using the produced developer carrier.

  The produced developer carrier was mounted on a laser beam printer Laser Jet9000 manufactured by Hewlett-Packard Co. having the developing device of FIG. 6, and a durability evaluation test of 35,000 sheets was performed while supplying the developer 1. As a regulating member used in the above developing device, the contact condition of the urethane blade used in Laser Jet 9000 is changed, and the linear pressure per 1 cm (g / cm) in the longitudinal direction of the developer carrier is 30 g / cm. Endurance evaluation was performed with 1 mm as the distance from the most upstream position of contact (upstream in the rotation direction of the developer carrying member) to the free end of the blade.

Evaluation Durability tests were conducted on the evaluation items listed below, and each developer carrier of Examples and Comparative Examples was evaluated.

  Image evaluation such as image density, fog, sleeve ghost, image stripe, halftone uniformity, toner transport amount (M / S) on developer carrier, abrasion resistance of resin coating layer and toner fusion at 23 ° C. / 60% normal temperature normal humidity (N / N) environment, 23 ° C / 5% normal temperature low humidity (N / L) environment, 30 ° C / 80% high temperature high humidity (H / H) environment Went.

  The evaluation results are shown in Tables 5 and 6.

(1) Image Density A reflection densitometer RD918 (manufactured by Macbeth) was used to measure the density of the solid black portion when solid printing was performed, and the average value was used as the image density.

(2) Fog density The reflectance (D1) of the solid white portion of the image-formed recording paper is measured, and the reflectance (D2) of an unused recording paper of the same cut as the recording paper used for image formation is further measured. , 5 values of D1-D2 were obtained, and the average value was taken as the fog density. The reflectance was measured with TC-6DS (manufactured by Tokyo Denshoku).

(3) Sleeve ghost The halftone image is developed so that the position of the developing sleeve that developed the image in which the solid white portion and the solid black portion are adjacent comes to the developing position at the next rotation of the developing sleeve and develops the halftone image. The shade difference appearing above was visually evaluated based on the following criteria.
A: No difference in shading is observed.
B: A slight shading difference is observed.
C: Practical use is possible although there is a slight difference in shading.
D: A shade difference that is a problem in practical use appears for one round of the sleeve.
E: The difference in shading that is a problem in practical use appears for two or more sleeves.

(4) Halftone uniformity (difference between haze and band)
The formed image was visually observed and evaluated according to the following criteria for the haze-like shade difference generated in the halftone and the strip-like shade difference running in the image formation progress direction.
AA: Uniform image.
A: A level where a slight difference in light and shade can be confirmed by looking closely, but it cannot be confirmed at a glance.
B: A level at which the difference in shading or banding appears slightly but does not matter.
C: Although the difference in shading or banding can be confirmed even at a distance, it is at a practical level.
D: A level at which the skin-like haze appears on the whole or the band-like shade difference can be clearly confirmed.
E: Level where the density is low and the low density band spreads over the entire surface.

(5) Image streaks For white streaks that occur in the halftone or solid black and run in the image formation progress direction, the formed images were visually observed and evaluated according to the following criteria.
A: The image cannot be confirmed at all.
B: Although it can be confirmed slightly when it is looked closely, it can hardly be confirmed at a glance.
C: Level that can be confirmed slightly with halftone, but not with solid black.
D: A level that can be confirmed with halftone but at a practical level, and a level that can be slightly confirmed with solid black.
E: Conspicuous to the extent that it is a practical problem with halftone, but practical level that can be confirmed with solid black.
F: Level at which a large number of streaks that cause practical problems occur in the entire solid black image.

(6) Toner transport amount (M / S)
The toner carried on the developing sleeve is sucked and collected by a metal cylindrical tube and a cylindrical filter, and the toner per unit area is obtained from the toner mass M collected through the metal cylindrical tube and the area S where the toner is sucked. The mass M / S (dg / m 2) was calculated and used as the toner transport amount (M / S).

(7) Abrasion resistance of resin coating layer The arithmetic average roughness (Ra) of the surface of the developer carrying member before and after the durability test and the amount of abrasion of the film thickness of the resin coating layer were measured. However, when measuring the developer carrier after durability, the toner fusion material on the surface of the developer carrier is removed by immersing in MEK solvent to remove the toner fusion material and further irradiating with ultrasonic waves. Measured after removal.

  For measurement of the amount of abrasion (film abrasion) of the resin coating layer, a laser dimension measuring device manufactured by KEYENCE was used. Using the controller LS-5500 and the sensor head LS-5040T, the sensor part was separately fixed to an apparatus equipped with a sleeve fixing jig and a sleeve feeding mechanism, and measurement was performed from the average value of the outer diameters of the sleeves. The measurement was divided into 30 with respect to the longitudinal direction of the sleeve and measured at 30 points. Further, after rotating the sleeve 90 ° in the circumferential direction, measurements were further made at 30 points, a total of 60 points, and the average value was taken. The outer diameter of the sleeve before application of the surface coating layer was measured in advance, the outer diameter after forming the surface coating layer and the outer diameter after durable use were measured, and the difference between them was taken as the coating film thickness and the amount of abrasion.

(8) Toner Fusion The surface of the developer carrier after the durability test was observed at about 200 times using an ultra-deep shape measuring microscope manufactured by KEYENCE, and the degree of toner fusion was evaluated based on the following criteria.
AA: A minute granular toner fusion product is slightly observed.
A: A minute granular toner fusion product is partially observed.
B: A minute but slightly elongated toner melt is partially observed in the circumferential direction.
C: Several fine streaky toner fusion products are observed in the circumferential direction.
D: Several slightly streaky toner fusion products are observed in the circumferential direction.
E: Many clear streaky toner fusion products are observed in the circumferential direction.

FIG. 3 is a schematic cross-sectional view showing a part of the developer carrier of the present invention. 1 is a schematic cross-sectional configuration diagram of an example of a surface modification device used in a surface modification step of toner particles used in the present invention. It is a schematic block diagram which shows an example of the top view of the dispersion | distribution rotor shown in FIG. It is a schematic diagram showing an embodiment of a developing device of the present invention when a magnetic one-component developer is used. It is a schematic diagram which shows other embodiment of the image development apparatus of this invention. It is a schematic diagram which shows other embodiment of the image development apparatus of this invention.

Explanation of symbols

1 Electrophotographic photosensitive drum (electrostatic latent image carrier)
2 Magnetic regulating blade (developer layer thickness regulating member)
3 Hopper (developer container)
4 Developer 5 Magnet roller (magnet)
6, 16 Metal cylindrical tube (base)
7, 17 Resin coating layer 8 Development sleeve (developer carrier)
9 Development bias power supply (bias means)
111 Elastic regulating blade N1, N2, S1, S2 Magnetic pole a Roughened particle b Graphitized particle c Coated resin 31 Classification rotor 32 Fine powder recovery 33 Raw material supply port 34 Liner 35 Cold air introduction port 36 Dispersion rotor 37 Product discharge port 38 Discharge valve 39 Guide ring 40 Square disc 41 First space 42 Second space

Claims (6)

The electrostatographic latent image carried on the electrostatic latent image bearing member a developer carrying member for carrying one component developer to visualize the developer carrying member has at least a substrate, formed on the surface of the base body by having a resin coating layer, the resin coating layer contains at least graphitized particles and coarse and particles,
The rough particles are composed of spherical conductive carbon particles having a volume average particle diameter of 8.7 to 18.8 μm,
The graphitized particles are particles obtained by baking bulk mesophase pitch particles or mesocarbon microbeads composed of a single phase and graphitizing the degree of graphitization p (002) to 0.23 to 0.79, and the volume average particle size in the resin coating layer is dispersed so as to 1.0～3.6Myuemu, whereby, in the measured surface shape using a focus optics laser of the resin coating layer, the crude The volume B of the fine irregularities formed by the graphitized particles in the constant area A of the region where the convexities are not formed by the particles satisfies the relationship of 4.7 ≦ B / A ≦ 6.2. And
Furthermore, the arithmetic mean roughness Ra of the said resin coating layer surface is 0.9-2.5 micrometers, The developing agent carrier characterized by the above-mentioned.   When the surface of the resin coating layer is observed at a magnification of 2000 × using a 100 × objective lens, the fixed area A of the region is 20 μm wide × 20 μm long without the convex portion due to the rough particles. The developer carrying member according to claim 1, which is an area region.   The developer carrier according to claim 1, wherein the resin coating layer contains a phenol resin as a binder resin.   The resin coating layer is a resin having at least one of an amino group, = NH group or -NH- group in a molecular chain, a quaternary ammonium salt that is positively charged with respect to iron powder, the graphitized particles, The developer carrying member according to claim 1, wherein the developer carrying member is formed of a coating liquid containing the roughening particles. Using the developer carrying member carrying the one-component developer, the one-component developer is transported to a developing region facing the electrostatic latent image bearing member, and the electrostatic latent image is conveyed by the transported one-component developer. In a developing method including a step of developing an electrostatic latent image carried on a carrier,
The developing method according to claim 1, wherein the developer carrying member is the developer carrying member according to claim 1.   The one-component developer is a toner comprising a binder resin and toner particles containing at least a magnetic substance, and the toner particles have an equivalent circle diameter of 3 μm or more and 400 μm or less measured by a flow type particle image measuring device. The average circularity of the toner particles is 0.935 or more and less than 0.970, and the ratio of toner particles having a number average particle size distribution of 0.6 μm or more and less than 3 μm is 0% or more and less than 20%. Development method.

Images