JP2007206647A - Electrophotographic developing method, developer carrier used in same, and process cartridge and electrophotographic apparatus using same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic developing method by which the stable charging capacity is obtained even in low humidity environment by suppressing excessive charging of toner particles in the low humidity environment and the development stability is secured by suppressing the reduction of developer concentration due to environmental change of temperature and humidity and the degradation of developing property such as deterioration of image quality of fogging, sleeve ghost, etc. <P>SOLUTION: In the electrophotographic developing method of performing development while moving a developer to an electrostatic latent image formed on an electrostatic latent image carrier, a developer carrier comprising a base body 2 and a resin covering layer 1 on the surface is used, wherein the resin covering layer contains a compound with sulfur atom and nitrogen atom, and the content of sulfur atom and the content of nitrogen atom satisfy a specific relation, and a developer comprising binder resin (a) and toner particles (b) containing magnetic bodies made of magnetic iron oxide is also used, wherein the toner particles satisfy the ratio of the content of iron atom to the content of carbon atom, and the liberation rate X of iron and iron compound from the toner particles satisfies a specific relation. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electrophotographic developing method applied to a copying machine, a printer or a facsimile receiving apparatus, a developer carrier used therefor, a process cartridge and an electrophotographic apparatus using the same. More specifically, an electrophotographic developing method for developing a latent image formed on an electrostatic latent image carrier incorporated in an apparatus utilizing electrophotography, a developer carrier used therefor, and a process cartridge using the developing method And electrophotographic apparatus.

  Electrophotographic methods used in electrophotographic apparatuses such as copying machines, facsimiles, and printers form an electrostatic latent image on an electrostatic latent image carrier (hereinafter also referred to as a photoreceptor) by various means, and In this method, an image is visualized with a developer, and this is transferred and fixed on a transfer material such as paper to obtain a printed matter.

  In such an electrophotographic method, a developing device used for developing an electrostatic latent image formed on a photosensitive member includes a developer container for containing a developer, a developer carrier having a roller shape, and a developer layer. A thickness regulating member is provided. Specifically, the developer carrier is provided so as to close the opening of the developer container, and a part of the developer carrier is exposed from the developer container, and is axially mounted so as to face the photoconductor at the exposed portion. The developer layer thickness regulating member is provided to face the developer carrier in the developer container. In such a developing device, the developer contained in the developer container is carried on the surface by a rotating developer carrying member, and is formed as a layered thin film on the surface of the developer carrying member by a developer layer thickness regulating member. Then, the surplus is returned to the developing container. At this time, in the case of the contact development method, the developer held on the surface of the developer carrier is opposed to the exposed photoreceptor while being frictionally charged by the developer layer thickness regulating member as the developer carrier rotates. It is conveyed to the development area. In the developing area, the toner moves onto the electrostatic latent image formed on the photosensitive member, and visualizes it to form a toner image. In the case of the non-contact development method, the developer on the surface of the developer carrying member is a layer having a film thickness that is smaller than the distance between the photosensitive member and the developer carrying member in the developing region by the developer layer thickness regulating member. In the developing area, the toner image is formed by flying on the electrostatic latent image on the photosensitive member.

  The developer used in such a developing apparatus is roughly classified into a two-component developer using carrier particles and a one-component developer using no carrier particles. Further, the one-component developer includes toner particles containing magnetic particles and a binder resin, and the magnetic one-component developer carried on the developer carrying member by the action of magnetic force is frictionless without containing magnetic particles. There is a non-magnetic one-component developer carried on a developer carrier by the action of electric charge. In such a magnetic one-component developer, a colorant such as carbon black generally used as a colorant is not used, and magnetic particles are also used as a colorant.

  In the two-component developer, a developer containing carrier particles such as glass beads and iron powder and toner particles is used. The development method using a two-component developer requires a sensor for detecting the toner particle concentration that decreases with use, a toner particle replenishing device that replenishes the consumed amount and keeps the toner particle concentration constant. For this reason, the developing device becomes large and heavy and has a complicated configuration, and the toner particles adhere to the carrier particles (spent) that occur with use, so that it is necessary to perform frequent maintenance such as replacement of the carrier particles. is there. However, the development method using a two-component developer is preferably used for color development because the developer concentration can be finely adjusted by a toner particle concentration sensor.

  On the other hand, in the developing method using a one-component developer, the developing device itself can be reduced in size and weight, and the frequency of maintenance can be reduced. However, in the magnetic one-component developer, dark black magnetic particles are used as toner. It becomes difficult to make color by using it. In recent years, there has been a demand for miniaturization of each component for the purpose of reducing the weight and size of an electrophotographic apparatus, and as a result, a developing apparatus using a one-component developer has been increasingly used as a color developing apparatus. Yes. However, in the case of using a magnetic one-component developer, fine adjustment of the charge amount of the toner particles is necessary, and various improvements have been made so that the toner particles can be uniformly charged to a desired charge amount. Toner particles having excellent charging uniformity and charging durability stability have not been obtained.

  As a problem in such a magnetic one-component developer, since toner particles are prepared by containing a considerable amount of fine powder magnetic material, toner particles produced when a part of the magnetic material is exposed to or released from the surface of the toner particles. Examples include poor fluidity and poor triboelectric chargeability. Such toner particles with poor fluidity and frictional chargeability have insufficient performance such as development characteristics (particularly fog characteristics) and transferability. As a result, a large amount of developer is formed on the photoreceptor after transfer. The situation of remaining will arise. This situation clearly appears especially under low humidity where the triboelectric charge amount tends to increase.

  By the way, as a trend in recent years, LED (light emitting diode) printers and LBP (laser beam printers) have become mainstream in the market, and resolutions of 300 dpi and 400 dpi have become 600 dpi, 800 dpi, and 1200 dpi. ing. Along with this, there has been a demand for higher definition in developing devices. Also, digitalization of copiers has become the mainstream, and designs aiming at so-called multi-functions that can be used simultaneously as facsimiles and printers are becoming main. For this reason, the difference between a copying machine and a printer is gradually narrowed, and a high-resolution and high-definition developing method is also required here. In order to cope with this problem, it has been proposed to reduce the particle size of toner particles, and toner particles having a central particle size of about 5 μm to 9 μm have become mainstream in response to the demand for high resolution. Yes. As the particle size of the toner particles becomes smaller, the instability of the triboelectric charging of the toner particles tends to increase, and uniform triboelectric charging of the toner particles becomes an important technique. As described above, when development is performed with toner particles having non-uniform charge amounts, image stability is deteriorated. However, when toner particles having small particle diameters are non-uniformly charged, image stability is clearly reduced. appear. This is because the adhesion force (such as van der Waals force) to the photoconductor on the small diameter toner particles in the transfer process is larger than the Coulomb force, and as a result, the amount of toner particles remaining on the photoconductor without being transferred is reduced. By increasing. Furthermore, since the fluidity of the small-diameter toner particles is deteriorated, the amount of charge imparted to each toner particle is likely to be non-uniform, and the toner particles with poor fog and transferability increase.

  With respect to the deterioration of the image characteristics accompanying the exposure of the magnetic material, many improvements have been made in terms of the material and structure of the toner particles. Among these, improvement of the magnetic material is mentioned in terms of the material of the toner particles. For example, a magnetic toner (Patent Document 1) using magnetic iron oxide containing a silicon element has been reported. However, here, the silicon element is intentionally present only in the inside thereof, and there is still a point to be improved in the fluidity of the toner particles. Moreover, the technique (patent document 2) which controls the shape of magnetic iron oxide to a spherical shape by adding a silicate is reported. In the magnetic iron oxide obtained by such a method, a large amount of silicate used for particle shape control is distributed inside the magnetic iron oxide, and there is little abundance on the surface. Although the fluidity of the toner particles is improved, the adhesion with the binder resin is insufficient. Furthermore, a method for producing triiron tetroxide in which a hydroxosilicate solution is added during the oxidation reaction (Patent Document 3) has also been reported. The triiron tetroxide obtained by this method is present in the form of a layer in the vicinity of the surface, and has a problem that the surface is weak against mechanical impacts such as friction.

  On the other hand, as an improvement in the structure of the toner particles, for example, special toner particles in which magnetic fine particles are contained only in specific portions inside the particles can be mentioned. Specifically, it is a pressure fixing toner manufactured by a two-step to three-step process in which a magnetic material is dry-attached after the core particles are manufactured and then a shell layer is formed, and the magnetic material is formed only in the toner intermediate layer. Existing ones (Patent Documents 4 and 5) have been reported. In addition, a toner having a structure in which a resin layer having no magnetic particles in the vicinity of the toner particle surface is formed with a certain thickness or more (Patent Document 6) has been reported.

  Furthermore, the flowability and the triboelectric chargeability were improved by preventing the magnetic material from being substantially exposed to the toner surface by a polymerization method using a hydrophobic iron oxide magnetic iron oxide. A small particle size magnetic toner (Patent Document 7) has been reported. Also, considering the degree of hydrophobicity of the magnetic material and compatibility with the binder resin, the release rate of iron released from the toner particles is lowered, and the exposure of the magnetic material to the toner surface is suppressed. It has been introduced that a toner having a high charge amount can be obtained (Patent Document 8).

  By using the magnetic toner particles described in Patent Document 7 and Patent Document 8, a great effect can be expected for solving the developability problem related to the conventional magnetic one-component developer. However, image stability caused by charge-up (excessive charging) phenomenon under low temperature and low humidity environment is a major issue in achieving high resolution and high definition by promoting the reduction of toner particle diameter. The problem of lowering is unresolved. As a result of the study by the present inventors, the toner particles in which the magnetic particles are contained only in a specific portion inside the particles described above are essentially free from the magnetic material on the surface, and are mainly covered with the binder resin. The surface becomes high resistance. In addition, it has been found that the amount of charge tends to increase due to a decrease in charge leakage sites and the ease of charge accumulation. Therefore, it has been found that the charge-up phenomenon is more likely to occur as the particle size of the toner particles is reduced and the specific surface area is increased, and such a charge-up phenomenon tends to occur frequently in a developing method having a high process speed.

  Further, Patent Document 4 describes that by adjusting the type / addition amount of the magnetic material and the thickness of the shell portion, the magnetic material can be present in the vicinity of the toner particle surface layer, and the surface resistance can be lowered to some extent. There is. However, since there is a restriction that only one magnetic layer can exist on the core surface, only low magnetic force toner particles can be obtained. For this reason, in the one-component development system using small-diameter toner particles, it is difficult to stably contain an amount of magnetic material that can withstand the restriction by magnetic force.

  On the other hand, as a means for improving the developability, an approach from a developer carrier has also been made. As the developer carrying member, for example, a metal, an alloy thereof or a compound thereof is molded into a cylindrical shape, and the surface thereof is processed to have a predetermined surface roughness by electrolysis, blasting, file, or the like. However, in such a developer-carrying member, when the developer layer thickness regulating member is brought into contact with the developer carrier, an excess amount of the developer is removed and an appropriate amount of the developer layer is formed on the surface. The toner particles present in the toner are given a much higher charge than the toner particles present on the surface side. For this reason, the force that attracts the inner toner particles to the surface of the developer carrying member (hereinafter referred to as “mirror force”) increases, so that the toner layer moves and rotates even when a load is applied by the developer layer thickness regulating member. And the friction with the developer carrier is suppressed. As a result, a non-uniform charge amount occurs between the outer toner particles and the inner toner particles that are frictionally charged by the developer layer thickness regulating member. Under such circumstances, it is difficult to perform good development and transfer, and the obtained image has not only uneven density and scattered characters, but also causes a problem of sleeve ghost.

  Resin in which a conductive material such as carbon and a solid lubricant such as graphite are dispersed on a metal developer carrier in order to suppress non-uniform charge and strong adhesion of toner particles in the developer layer. A method of forming a resin coating layer made of is reported (Patent Document 7). In the case of having a resin coating layer in which crystalline graphite is dispersed, the surface of the resin coating layer has lubricity from the adjacent piece-like structure of crystalline graphite, so it is effective against charge-up and sleeve ghost. (Patent Document 9). However, in order to appropriately charge the toner particles, it is necessary to further improve the configuration of the resin coating layer.

As an improvement of the resin coating layer, it consists only of an intermediate layer such as rubber on a cored bar, and carbon, oxygen, hydrogen and nitrogen formed by vapor deposition, and the atomic ratio N / C of nitrogen and carbon is 0. A toner carrier (Patent Document 10) in which functional layers of 0.005 or less are sequentially laminated has been reported. This is intended to reduce the triboelectric charge imparting ability of the negatively chargeable toner by reducing the nitrogen atom existing ratio on the surface of the toner carrier. Although this toner carrier can alleviate the charge-up of the toner particles to some extent, it is not sufficient in an environment where triboelectric charges are likely to occur, such as a low humidity environment. Further, in the two-component development method using a negatively charged toner, at least the surface has a resin containing nitrogen in the resin structure, and the content ratio is 100 carbon atoms or less per nitrogen atom on average. A developing roller (Patent Document 11) has been reported. Further, the resin coating layer is made of a resin containing a high molecular compound or a low molecular compound having a nitrogen atom in the molecular structure, and the composition ratio N / C of the carbon atom to the nitrogen atom by the surface X-ray photoelectron spectroscopic analysis is 0. A developing roller (Patent Document 12) of 10 to 0.35 has been reported. These all promote the triboelectric charge on the toner particles, thereby increasing the charge amount of the toner particles and improving the development characteristics. The toner particles are excellent in suppressing excessive charging of the toner particles under low temperature and low humidity. Image forming cannot be performed.
Japanese Unexamined Patent Publication No. 63-279352 Japanese Patent Publication No. 03-009045 Japanese Patent Laid-Open No. 61-034070 JP 60-003647 A JP 63-089867 A JP 07-209904 A JP 2001-235897 A JP 2002-258526 A JP-A-01-277265 Japanese Patent Laid-Open No. 07-064388 JP 2001-228701 A JP 2003-122108 A

  An object of the present invention is to suppress excessive charging of toner particles in a low-humidity environment, have a stable charging ability even in a low-humidity environment, and developability such as a decrease in image density, fogging, and deterioration in image quality. It is an object of the present invention to provide an electrophotographic developing method that suppresses a decrease in the thickness and has development stability.

  Another object of the present invention is to suppress a decrease in developability such as a decrease in image density, fog and deterioration of image quality even in a high humidity environment, and has development stability, excellent durability, and sleeve. An object of the present invention is to provide an electrophotographic developing method capable of suppressing the occurrence of ghost. Furthermore, it can be applied to high-speed, high-resolution, and high-definition electrophotographic devices regardless of low-humidity or high-humidity environments, and it can stably obtain high-density and high-definition images that are uniform and free from uneven density. It is an object of the present invention to provide a developer carrying member, a process cartridge and an electrophotographic apparatus using the developer carrying member.

  The inventors of the present invention have made extensive studies on the uniform and stable charging of toner particles in a developing system using a magnetic developer. As a result, the surface of the developer carrying member has a resin coating layer containing a compound having a sulfur atom and a nitrogen atom, and the content ratio Y of the sulfur atom and the nitrogen atom has a specific value. In addition, the iron atoms on the surface of the toner particles are in a specific ratio with respect to the carbon atoms, and there are iron and iron compounds that are liberated from the toner particles at a specific release rate X. It has been found that the toner particles can be prevented from being overcharged in a low-humidity environment and the like. Based on such knowledge, it has been found that by using a developer containing such toner particles and a developer carrier, it has excellent development characteristics in high-speed, high-resolution and high-definition electrophotographic apparatuses. The present invention has been completed.

That is, according to the present invention, the developer carrying member carrying the developer contained in the developing container is rotated to form a layer having a constant thickness by the developer layer thickness regulating member that contacts the developer carrying member. In the electrophotographic developing method, the developed developer is transported to a developing region facing the electrostatic latent image carrier and moved to the electrostatic latent image formed on the electrostatic latent image carrier to perform development. The resin coating layer contains a compound having a sulfur atom and a nitrogen atom, and the content of sulfur atoms by X-ray photoelectron spectroscopy analysis on the surface of the resin coating layer is S (1) (atomic% ), When the nitrogen atom content is N (atomic%) and Y = S (1) / N, formula (1) and formula (2)
0.050 ≦ S (1) ≦ 1.500 (1)
0.100 ≦ Y ≦ 1.500 (2)
A developer carrier that satisfies
Toner particles containing a magnetic material including a binder resin and magnetic iron oxide, and the toner particles have a carbon atom content A (atomic%) and an iron atom content B (atomic atoms) by X-ray photoelectron spectroscopy on the surface. %), The ratio B / A of the content ratio of iron atoms to the content ratio A of carbon atoms is less than 0.001, and iron and iron compounds released from toner particles have a release ratio X (% ), The formula (4) and the formula (5)
X ≦ 3.00 (4)
−0.05X + 0.2 ≦ Y ≦ −0.3X + 1.5 (5)
The present invention relates to an electrophotographic developing method characterized by using a developer satisfying the above requirements.

  The present invention also relates to a developer carrying member that is used in the electrophotographic developing method of the present invention, a process cartridge that uses the electrophotographic developing method of the present invention, and an electrophotographic apparatus. .

  The electrophotographic image developing method of the present invention can suppress excessive charging of toner particles in a low-humidity environment, has a stable charging ability even in a low-humidity environment, reduces image density, and reduces fog and image quality. It suppresses the deterioration of developability such as development stability. In addition, even under high-humidity environment, it suppresses the deterioration of developability such as image density reduction, fogging, and image quality deterioration, has development stability, excellent durability, and suppresses the occurrence of sleeve ghost. Can do. Furthermore, it can be applied to high-speed, high-resolution, high-definition electrophotographic devices regardless of whether the humidity is low or high-humidity, and it is possible to stably obtain uniform, non-uniform density, high image density, and high-definition images. Can do.

  The developer carrying member, the process cartridge, and the electrophotographic apparatus of the present invention achieve high speed, high resolution, and high definition, and can stably obtain a high-density image with a high image density and a high density without uniform density unevenness. be able to.

  In the electrophotographic developing method of the present invention, the developer carrying member carrying the developer contained in the developing container is rotated, so that the developer layer thickness restricting member that contacts the developer carrying member rotates to have a constant thickness. The developer formed in the layer is conveyed to a development area facing the electrostatic latent image carrier. Then, an electrophotographic developing method is performed in which development is performed by moving the electrostatic latent image formed on the electrostatic latent image carrier. A developer carrier having a substrate and a resin coating layer on the surface is used. The resin coating layer contains a compound having a sulfur atom and a nitrogen atom, the sulfur atom content by surface X-ray photoelectron spectroscopy is S (1) (atomic%), and the nitrogen atom content is N (atomic%). ), Y = S (1) / N, the expressions (1) and (2) are satisfied.

0.050 ≦ S (1) ≦ 1.500 (1)
0.100 ≦ Y ≦ 1.500 (2)
A developer containing toner particles containing a magnetic material containing a binder resin and magnetic iron oxide is used. When the toner particles have a carbon atom content A (atomic%) and an iron atom content B (atomic%) by surface X-ray photoelectron spectroscopy, the iron atom content relative to the carbon atom content A The ratio B / A has a value of less than 0.001. The iron and iron compound released from the toner particles satisfy the equations (4) and (5) when the liberation rate X (%).

X ≦ 3.00 (4)
−0.05X + 0.2 ≦ Y ≦ −0.3X + 1.5 (5)
[Development container]
The developing container used in the electrophotographic developing method of the present invention may be any material, shape, etc. as long as it can accommodate a developer. For example, the developer carrying member may be rotatably installed so as to have an opening and close the opening.
[Developer layer thickness regulating member]
Further, the developer layer thickness regulating member used in the electrophotographic developing method of the present invention can remove the excess of the developer carried on the developer carrying member and return it to the developing container, and can charge the developer. Anything is acceptable. For example, the developer layer thickness regulating member is made of an elastic material, is provided in contact with the developer carrier in the developer container, and is carried on the developer layer thickness carrier by rotating the developer carrier. For example, the developer is scraped off and the toner particles on the developer carrying member are triboelectrically charged. As a material for this type of developer layer thickness regulating member, a material having rubber elasticity such as silicone rubber, urethane rubber, styrene butadiene rubber or the like is suitable. Furthermore, an organic resin layer such as polyamide, polyimide, nylon, melamine, melamine cross-linked nylon, phenol resin, fluororesin, silicone resin, polyester resin, urethane resin, styrene resin may be provided. Alternatively, an elastic plate made of a material having metal elasticity such as phosphor bronze or stainless steel is also a good example. Further, it is made of a metal material and is provided with a gap from the developer carrier, and the developer on the developer carrier is made thinner than the distance between the photosensitive member and the developer carrier in the development region. While forming in a layer form, you may charge a developing agent. As a material for this type of developer layer thickness regulating member, iron, aluminum, SUS or the like is suitable.
[Developer carrier]
The developer carrier used in the electrophotographic developing method of the present invention has a resin coating layer on the substrate surface. Along with the rotation of the developer carrier, the developer layer is formed into a layer by the developer layer thickness regulating member, adjusted to an appropriate amount, and charged and carried on the surface of the developer is transported to the development area outside the developer container. The electrostatic latent image can be developed by moving onto the electrostatic latent image formed on the photosensitive member provided facing the developer carrying member. The developer carrier may be non-magnetic in relation to the developer described later, but preferably supports the magnetic developer by magnetic force, and preferably includes a magnet such as a magnet roller.
[Substrate]
The shape of the substrate provided on the developer carrying member used in the electrophotographic developing method of the present invention may be any of a cylinder, a column, a belt, etc., but in the developing method not in contact with the photoreceptor, a cylinder, A cylinder is preferred. When the developer is a magnetic one-component type, the base material is preferably a nonmagnetic metal or alloy such as aluminum, stainless steel, or brass, and aluminum is preferable from the viewpoint of material cost and ease of processing. When the developer is a non-magnetic one-component type, in addition to non-magnetic metals and alloys, those having magnetism such as iron, nickel, and stainless steel can be used.

The substrate is preferably formed or processed with high accuracy in order to improve the uniformity of the image. For example, the straightness in the longitudinal direction is preferably 30 μm or less, more preferably 20 μm or less, and even more preferably 10 μm or less. As the runout of the gap between the developer carrying member and the photosensitive member, for example, it is measured as the runout of the gap with the vertical surface when the developer carrying member is rotated by abutting against the vertical surface through a uniform spacer. be able to. The measured value is preferably 30 μm or less, more preferably 20 μm or less, and still more preferably 10 μm or less.
[Resin coating layer]
The resin coating layer provided on the surface of the developer carrying member used in the electrophotographic development method of the present invention is a layer containing a compound having a sulfur atom and a nitrogen atom in the resin (binder resin).

  As the resin (binder resin) contained in the resin coating layer, generally known resins can be used. For example, phenolic resin, epoxy resin, polyester resin, alkyd resin, melamine resin, benzoguanamine resin, polyurethane resin, urea resin, silicone resin, polyimide resin, or other heat or photo-curing resin, styrene resin, vinyl resin, polyether A thermoplastic resin such as a sulfone resin, a polycarbonate resin, a polyphenylene oxide resin, a polyamide resin, a fluororesin, a fiber-based resin, and an acrylic resin can be used. Among these, those having excellent mechanical properties such as phenol resin, polyether sulfone resin, polycarbonate resin, polyphenylene oxide resin, polyamide resin, polyester resin, polyurethane resin, styrene resin, and acrylic resin are used for the resin coating layer. Since high durability can be provided, it is preferable.

Among these resins, in particular, a nitrogen atom-containing resin having one or more of —NH ₂ , ═NH and —NH— is a combination with a compound having a sulfur atom and a nitrogen atom, particularly a quaternary ammonium salt. Is preferable because excessive charging of toner particles can be suppressed. Examples of —NH ₂ and ═NH include a substituent bonded to the main chain and the side chain, and —NH— includes —NH— constituting the main chain in addition to the case of being included in the side chain. Bonding can be mentioned. Examples of such nitrogen atom-containing resins include phenol resins, polyamide resins, epoxy resins using a polyamide as a curing agent, urethane resins, and these resins manufactured using a nitrogen-containing compound such as ammonia as a catalyst in the manufacturing process. And a copolymer containing a part thereof. These resins can easily incorporate a compound having a sulfur atom and a nitrogen atom into the binder resin structure of the coating resin layer when molding the coating resin layer.
[Compounds having sulfur and nitrogen atoms]
The compound having a sulfur atom and a nitrogen atom contained in the coating resin layer may be a compound containing a sulfur atom and a nitrogen atom, respectively, but contains a sulfur atom and a nitrogen atom in one molecule. Is preferred. Specific examples of such compounds include quaternary ammonium salt compounds that are positively charged with respect to iron powder, as specifically described in JP-A-10-3204040. A quaternary ammonium salt compound that is positively charged with respect to the iron powder is preferable from the viewpoint of enabling good charging to the developer. The iron powder here refers to carrier iron powder having a center particle diameter of 30 μm to 200 μm and not coated with resin. Specific examples thereof include EFV200 / 300 (manufactured by Powdertech), DSP138 (DOWA Iron) For example, manufactured by Flour Industries Co., Ltd.).

  More preferably, the compound having a sulfur atom and a nitrogen atom in the molecular structure contains a sulfonic acid group. Further, the compound having a sulfur atom and a nitrogen atom in one molecule is preferably a quaternary ammonium salt compound containing a nitrogen atom as a quaternary ammonium ion and a sulfur atom in a counter ion of an ammonium ion. Such a quaternary ammonium salt compound can control the charge amount to the toner particles, and can remarkably obtain the effect of suppressing the excessive charge of the developer. For this reason, it is possible to suppress the charge-up of the developer on the developer carrying member, and to maintain the high charging stability of the developer. As a result, environmental stability such as low temperature and low humidity in electrophotographic development and It can have long-term stability of high-definition images.

  Although the reason for this is not clear, compounds having sulfur and nitrogen atoms in one molecule, especially quaternary ammonium salt compounds that are positively charged to iron powder, are added to the binder resin. Is uniformly dispersed. Furthermore, when the binder resin is the above nitrogen atom-containing resin, the compound having a sulfur atom and a nitrogen atom in one molecule has improved dispersibility, is more uniformly dispersed, and further binds to the resin. Then, it is considered that the charging property of counter ions of ammonium ions is increased and expressed, and as a result, the binder resin having such a compound has negative charging property. Since the binder resin contains sulfur atoms in the counter ions of ammonium ions, the negative chargeability can be further improved.

  The quaternary ammonium salt compound may be any compound as long as it has a positive chargeability with respect to iron powder, and examples thereof include a compound represented by the chemical formula (A).

式中、Ｒ１〜Ｒ４は、独立して、置換基を有してもよいアルキル基、または置換基を有してもよいアリール基を表し、Ｘ^-は酸イオンを表わす。

In the formula, R1 to R4 independently represent an alkyl group which may have a substituent or an aryl group which may have a substituent, and X ⁻ represents an acid ion.

Specific examples of the acid ion represented by X ⁻ in the formula (A) include an organic sulfate ion, an organic sulfonate ion, an organic phosphate ion, a molybdate ion, a tungstate ion, a molybdenum atom, or a heteropolyacid containing a tungsten atom. An ion etc. can be mentioned. Among these, a sulfonic acid group can be mentioned as a particularly preferable one.

  Specific examples of the quaternary ammonium salt compound include those shown in the following Tables 1-1 to 1-3.

このような硫黄原子及び窒素原子を有する化合物は、例えば、アミノ基またはイミノ基を有する結着樹脂１００質量部に対して、３質量部〜１００質量部の範囲で含有させることが好ましい。このような範囲で含有されることにより、結着樹脂に含まれる窒素原子などと相俟って、樹脂被覆層の表面の硫黄原子と、窒素原子との含有率を式（１）及び式（２）を満たす範囲にすることができる。尚、硫黄原子及び窒素原子を有する化合物の含有量が上記範囲外であっても、後述するように、樹脂被覆層形成のための製造条件を選択することにより、樹脂被覆層の表面の硫黄原子と、窒素原子との含有率を式（１）及び式（２）を満たす範囲にすることもできる。
［樹脂被覆層の特性］
［硫黄原子及び窒素原子の含有率］
樹脂被覆層は、表面のＸ線光電子分光分析による硫黄原子の含有率をＳ（１）（原子％）、窒素原子の含有率をＮ（原子％）、Ｙ＝Ｓ（１）／Ｎとするとき、式（１）及び式（２）を満たすことが好ましい。

Such a compound having a sulfur atom and a nitrogen atom is preferably contained, for example, in the range of 3 to 100 parts by mass with respect to 100 parts by mass of the binder resin having an amino group or an imino group. By being contained in such a range, in combination with nitrogen atoms and the like contained in the binder resin, the content ratios of sulfur atoms and nitrogen atoms on the surface of the resin coating layer are expressed by the formulas (1) and ( It can be in a range satisfying 2). Even if the content of the compound having a sulfur atom and a nitrogen atom is outside the above range, as described later, by selecting the production conditions for forming the resin coating layer, the sulfur atom on the surface of the resin coating layer is selected. And the content rate with a nitrogen atom can also be made into the range which satisfy | fills Formula (1) and Formula (2).
[Characteristics of resin coating layer]
[Content of sulfur atom and nitrogen atom]
The resin coating layer has a sulfur atom content of S (1) (atomic%), a nitrogen atom content of N (atomic%), and Y = S (1) / N by surface X-ray photoelectron spectroscopy. Sometimes, it is preferable to satisfy | fill Formula (1) and Formula (2).

0.050 ≦ S (1) ≦ 1.500 (1)
0.100 ≦ Y ≦ 1.500 (2)
If the content S (atomic%) of sulfur atoms on the surface of the resin coating layer is 0.050 atomic% or more, the charge imparting ability to the developer is not excessively increased, and charging is performed particularly in a low humidity environment. The accompanying decrease in developability can be suppressed. If the sulfur atom content S (1) (atomic%) is 1.500 atomic% or less, a sufficient amount of charge can be imparted to the developer, particularly in a low concentration in a high humidity environment. A decrease in developability can be suppressed.

  Further, if the ratio Y = S (1) / N of the sulfur atom content S (1) (atomic%) to the nitrogen atom content N (atomic%) is 0.100 or more, the nitrogen atom content Therefore, it is possible to suppress an increase in charge imparting ability to the developer and to suppress a decrease in developability due to the charge-up of the developer. If Y is 1.500 or less, the sulfur atom content is low, a sufficient amount of charge can be imparted to the developer, and a decrease in developability can be suppressed.

  Further, the nitrogen atom content N (atomic%) is preferably in a range that satisfies the formula (3) with respect to the carbon atom content C (atomic%) on the surface of the resin coating layer.

0.005 ≦ N / C ≦ 0.070 (3)
If the nitrogen atom content N (atomic%) is 0.005 or more with respect to the carbon atom content C (atomic%) on the surface of the resin coating layer, a sufficient amount of charge is imparted to the developer. Therefore, the time required for starting up the charging can be shortened. If the nitrogen atom content N (atomic%) is 0.070 or less with respect to the carbon atom content C (atomic%) on the surface of the resin coating layer, the charge imparting ability of the developer is increased. It is possible to suppress the deterioration of developability due to the developer charge-up. When the nitrogen atom content N (atomic%) on the surface of the resin coating layer is within the range of the formula (3) with respect to the carbon atom content C (atomic%), the developer of the resin coating layer is obtained. The charge imparting ability can be made more appropriate.

  In addition, when the content of sulfur atoms by X-ray photoelectron spectroscopy inside the resin coating layer of the developer carrier is S (2) (atomic%), Z = S (2) / S (1) It is preferable that it exists in the range which satisfy | fills Formula (6).

0.300 ≦ Z ≦ 0.900 (6)
That is, the compound having a sulfur atom and a nitrogen atom is unevenly distributed on the surface of the resin coating layer, and the abundance in the resin coating layer is preferably smaller than the abundance on the surface. If the Z value is 0.300 or more, the charge imparting ability to the developer is not excessively increased, and a decrease in developability accompanying initial charge-up can be suppressed particularly in a low humidity environment. Further, if the Z value is 0.900 or less, a sufficient charge amount can be imparted to the developer even after printing a large number of sheets, and developability such as a low durable density in a high humidity environment. Can be suppressed.

  Here, the content of nitrogen atoms, sulfur atoms, and carbon atoms on the surface of the resin coating layer can include values based on the measurement under the following conditions of X-ray photoelectron spectroscopy analysis on the surface of the resin coating layer. An X-ray photoelectron spectroscopic analysis used for measuring each atomic ratio on the toner particle surface, which will be described later, can include the same method.

  X-ray photoelectron spectroscopic analysis is performed under the following conditions using Quantum 2000 manufactured by ULVAC-PHI.

X-ray source: Monochrome Al Kα
Xray Setting: 100 μmφ (100 W (20 KV))
Photoelectron extraction angle: 45 degrees Neutralization condition: Combined use of neutralization gun and ion gun Analysis area: 300 × 1500 μm
Pass Energy: 11.75 eV
Step size: 0.05eV
Here, the quantitative analysis of each atom includes C 1s (Bonding Energy: 280 eV to 295 eV), N 1s (Bonding Energy: 395 eV to 410 eV), O 1s (Bonding Energy: 525 eV to 540 eV), S 2p (Bonding: Bonding Energy: 175 eV) and Fe 2p3 (Bonding Energy: 706 eV to 730 eV) peaks are used to determine each atomic concentration (atomic%).

The content of sulfur atoms inside the resin coating layer is determined by cutting the resin coating layer on the developing sleeve in an oblique direction using a microtome ULTRACUT UCT made by Leica, and 1 μm to 2 μm inside from the resin coating layer surface. The value based on the measurement of the X-ray photoelectron spectroscopic analysis under the same conditions as described above can be given.
[Volume resistance value]
Such a resin coating layer has a volume resistance value in order to suppress sticking of the developer on the developer carrying member due to charge-up and poor frictional charging of the developer caused by charge-up of the developer. It is preferably 10 ⁴ Ω · cm or less. More preferably, it is 10 ³ Ω · cm or less. If the volume resistivity of the resin coating layer is less 10 ⁴ Ω · cm to suppress triboelectric charging of failure to the developer, the results, blotches (spot image and wave pattern image) or occurrence of image density reduction Can be suppressed.

  Here, specific examples of the volume resistance value of the resin coating layer include measured values under the following measurement conditions. As such a condition, a resin coating layer having a thickness of 7 μm to 20 μm is formed on a PET sheet having a thickness of 100 μm by using the same coating liquid that constitutes the resin coating layer on the developer carrier. A four-terminal probe is attached to AP (Mitsubishi Yuka Co., Ltd.) for measurement. The measurement environment can be 20 ° C. to 25 ° C., 50% RH to 60 RH%.

  In order to adjust the resistance value of the resin coating layer to the above value, it is preferable to include the conductivity-imparting particles (conductive agent) listed below in the resin coating layer. Examples of the conductivity-imparting particles to be used include fine powders of metals such as aluminum, copper, nickel and silver, and conductivity such as antimony oxide, indium oxide, tin oxide, titanium oxide, zinc oxide, molybdenum oxide and potassium titanate. Examples thereof include metal oxides, various carbon fibers, furnace black, lamp black, thermal black, acetylene black, channel black and other conductive carbon blacks, and further metal fibers. Among these, conductive carbon black, especially conductive amorphous carbon, is particularly excellent in electrical conductivity, is filled with a polymer material, imparts conductivity, and can have any conductivity only by controlling the amount added. Since it can be obtained, it is preferably used. In addition, the dispersion stability and coating stability are also improved due to the thixotropic effect of the paint.

  The amount of conductive carbon black added varies depending on the particle size, but is preferably in the range of 1 to 100 parts by mass with respect to 100 parts by mass of the binder resin. When the amount of conductive carbon black added is 1 part by mass or more, adhesion of toner particles to the binder resin can be suppressed and the resistance value of the resin coating layer can be lowered to a desired level. If the amount of conductive carbon black added is 100 parts by mass or less, the resistance value can be lowered to a desired level by suppressing a decrease in the strength (wearability) of the resin coating layer.

  Examples of the primary particle size of the conductive carbon black include 10 nm to 100 nm. If the primary particle size is 10 nm or more, the cohesiveness between the carbon blacks is low, the paint obtained by dispersing with the binder resin or the like is prevented from becoming highly viscous, and the carbon black in the paint is uniformly dispersed. be able to. If the primary particle diameter is 100 nm or less, it is possible to avoid the carbon black from being scattered in the resin coating layer, and the charge when a developing bias is applied due to the uneven conductivity on the surface of the resin coating layer. Occurrence of leakage can be suppressed.

  In addition to providing conductivity, it is preferable that the resin coating layer contains graphitized particles for the purpose of improving the film strength and surface lubricity in addition to the conductivity of the resin coating layer. The graphite particles preferably have a graphitization degree p (002) of 0.20 to 0.95. The graphitization degree p (002) is said to be the Franklin p value, and can be obtained from the graphite lattice interval d (002) obtained from the X-ray diffraction diagram of the graphitized particles by the calculation formula (7). . This p (002) value indicates the proportion of disordered portions of the stack of carbon hexagonal mesh planes. The smaller this value, the greater the degree of graphitization.

p (002) = 3.440-0.086 (1 -d 2) (7)
When p (002) of the graphitized particles is 0.95 or less, the wear resistance is excellent, and the decrease in conductivity and lubricity can be suppressed, and induction of developer charge-up can be suppressed. Deterioration of image quality such as sleeve ghost, fog, and image density can be suppressed, and further, when a developer layer thickness regulating member is used, generation of blade flaws and occurrence of streaks and density unevenness in the image can be suppressed. Moreover, if this p (002) is 0.20 or more, the graphitized particles are excellent in wear resistance, and the deterioration of the wear resistance and mechanical strength of the resin coating layer surface can be suppressed. By using graphitized particles having p (002) in the above range, it has good conductivity and high lubricity, suppresses a decrease in mechanical strength of the resin coating layer, and suppresses selective scraping. It is possible to further improve the durability.

  Here, as the value of graphitization degree p (002) of the graphitized particles, specifically, a value obtained by the calculation formula (7) based on a measured value by the following method can be exemplified.

  The lattice spacing d (002) obtained from the X-ray diffraction spectrum of graphite is measured by a powerful fully automatic X-ray diffractometer MXP18 system manufactured by Mac Science. For the lattice spacing d (002), CuKα is used 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: 18kW
Goniometer: Horizontal goniometer Monochromator: Used 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
Specific examples of such graphitized particles include graphite, and graphitized particles obtained by firing mesocarbon microbead particles and bulk mesophase pitch particles. Of these, specific examples of graphite include natural graphite and artificial graphite. Artificial graphite can be obtained by solidifying pitch coke with tar pitch or the like and firing it once at about 1200 ° C. and then placing it in a graphitization furnace to treat it at a high temperature of about 2300 ° C. to obtain a carbon crystal grown. it can. Natural graphite is produced from the ground by being completely graphitized by natural geothermal heat and underground high pressure for a long time. Such graphite is a dark gray to black glossy very soft slippery crystalline mineral with excellent properties such as heat resistance, chemical stability, lubricity, and fire resistance. It is widely used industrially in the form of powders, solids and paints for materials. Some crystal structures belong to the hexagonal system and other rhombohedral systems, and have a complete layered structure. Regarding electrical characteristics, free electrons exist between carbon and carbon bonds, making it a good conductor of electricity. Furthermore, graphite has anisotropy in the crystal structure as seen in “cleavage”, which is one of the structural properties, and when it appears on the surface of the resin coating layer, it can impart lubricity to the surface. It is a preferred material because it is possible.

  Further, graphitized particles obtained by firing mesocarbon microbead particles or bulk mesophase pitch particles are different from graphite in raw materials and manufacturing processes. Although the graphitized particles of these particles have a slightly lower degree of graphitization than crystalline graphite, they have high conductivity and lubricity similar to crystalline graphite. Further, the shape of the particles is a lump or a substantially spherical shape, unlike the flakes or needles of crystalline graphite, and the hardness of the particles themselves is relatively high. Since graphitized particles having such characteristics are easily dispersed uniformly in the resin coating layer, uniform surface roughness and wear resistance are imparted to the surface of the resin coating layer, and the shape of the particles themselves hardly changes. Further, even if the resin coating layer is scraped or the particles themselves fall off due to the influence, the particles may protrude or be exposed again from the resin coating layer, and the change in the surface shape can be suppressed to a small level. . In addition, toner particles can be prevented from being charged up more than when crystalline graphite is used, and the ability to impart triboelectric charge to the toner particles can be improved.

  Usually, an organic compound having a boiling point of 500 ° C. or higher is carbonized via a solid phase or a liquid phase when heated in an inert gas phase under normal pressure, but begins to decompose at a temperature up to about 200 ° C., Cyclization occurs in the residue, followed by aromatization up to 400 ° C. Beyond this temperature, aromatic polycondensation proceeds. Among them, those that are liquid at this temperature, such as condensed polycyclic aromatics and pitches that are a mixture thereof, form a liquid crystal state composed of condensed polycyclic aromatic planar molecules at 400 ° C. or higher. This liquid crystal is called mesophase. In the mesophase, the polymer is further polymerized up to 500 ° C. and solidifies while forming a layered structure. The layered structure has a high selective orientation and has a property of being easily graphitized by high-temperature treatment. Therefore, the crystallinity of the graphitized particles is increased by graphitizing using optically anisotropic particles such as mesocarbon microbead particles and bulk mesophase pitch particles as raw materials, and consisting of a single phase. In addition, a lump shape or a substantially spherical shape can be maintained. The optical anisotropy of the above-mentioned raw materials is caused by the lamination of aromatic molecules, and the order is further developed by graphitization treatment, and graphitized particles having high crystallinity are obtained.

  As a method for producing mesocarbon microbead particles, for example, coal-based heavy oil or petroleum-based heavy oil is heat-treated at a temperature of 300 ° C. to 500 ° C. and polycondensed to obtain crude mesocarbon microbead particles. This is subjected to treatments such as filtration, stationary sedimentation, and centrifugal separation to separate the mesocarbon microbead particles, and after the separation, the purified product is obtained by washing with a solvent such as benzene, toluene, xylene, and drying. A method can be mentioned.

  As a method of obtaining graphitized particles by graphitizing mesocarbon microbead particles, first, the mesocarbon microbead particles that have been dried are first mechanically dispersed with a gentle force that does not cause destruction. It is preferable in order to suppress aggregation of the subsequent particles and obtain a uniform particle size. The mesocarbon microbead particles that have finished the primary dispersion are subjected to primary heat treatment at a temperature of 200 ° C. to 1500 ° C. in an inert atmosphere to be carbonized. For the carbide after the primary heat treatment, it is preferable to mechanically disperse the carbide with a mild force that does not destroy the carbide in order to suppress aggregation of particles after graphitization and to obtain a uniform particle size.

  The carbide that has undergone the secondary dispersion treatment can be subjected to a secondary heat treatment at 2000 ° C. to 3500 ° C. in an inert atmosphere to obtain desired graphitized particles.

  Examples of the method for obtaining the bulk mesophase pitch particles include a method of extracting β-resin by solvent fractionation from coal tar pitch or the like, and performing hydrogenation and heavy treatment. Further, after the heavy treatment, it can be obtained by pulverizing and then removing the solvent-soluble component with benzene or toluene. The obtained bulk mesophase pitch particles preferably have a quinoline soluble content of 95% by mass or more. That is, if the quinoline-soluble content is 95% by mass or more, the inside of the particles is liable to be liquid phase carbonized, and solid phase carbonization makes it easy to change the particles from crushed to spherical.

  As a method for obtaining graphitized particles by graphitizing the bulk mesophase pitch particles, first, the bulk mesophase pitch particles are finely pulverized to 2 to 25 μm and heat-treated at 200 ° C. to 350 ° C. in air. Oxidize. By this oxidation treatment, only the surface of the bulk mesophase pitch particles is infusible, and melting and fusion during the graphitizing heat treatment in the next step can be suppressed. The oxidized mesophase pitch particles preferably have an oxygen content of 5% by mass to 15% by mass. If it is 5% by mass or more, it is possible to suppress the fusion of particles during heat treatment, and if it is 15% by mass or less, it is possible to suppress oxidation inside the particles and obtain a product that is changed from crushed to spherical. it can.

  The final graphitized particles can be obtained by heat-treating the oxidized bulk mesophase pitch particles at 2000 ° C. to 3500 ° C. in an inert atmosphere such as nitrogen or argon. In the method for producing graphitized particles using mesocarbon microbead particles or bulk mesophase pitch particles, the final firing temperature of the graphitized particles is preferably 2000 ° C to 3500 ° C, more preferably 2300 ° C to 3200 ° C. If the firing temperature is 2000 ° C. or higher, graphitized particles that have been sufficiently graphitized can be obtained, and a decrease in electrical conductivity and lubricity can be suppressed and the occurrence of charge-up of toner particles can be suppressed. . For this reason, deterioration of image quality such as sleeve ghost, fog, image density, etc. is suppressed, occurrence of trace scratches is suppressed when a developer regulating member is used in contact, and occurrence of streaks, density unevenness, etc. is suppressed in the image. can do. On the other hand, if the firing temperature is 3500 ° C. or lower, the excessive increase in the graphitization degree of the graphitized particles can be suppressed, the decrease in hardness can be suppressed, and the resin coating layer surface has excellent wear resistance. The abrasion resistance, the mechanical strength of the resin coating layer, and the charge imparting property to the toner particles.

  Regardless of the production method, it is preferable that the graphitized particles have a uniform particle size distribution to some extent by classification because the surface shape of the resin coating layer can be made uniform.

  Such graphitized particles preferably have a volume average particle size of 0.5 μm to 30 μm, and more preferably 1 μm to 25 μm. If the volume average particle size is 0.5 μm or more, it has the effect of imparting uniform roughness to the surface of the resin coating layer and the effect of improving the charging performance, and the developer can be charged sufficiently quickly and uniformly. For this reason, generation | occurrence | production of the charge-up of the toner particle by abrasion of a resin coating layer, the deterioration of a ghost, an image density fall, etc. can be suppressed. If the volume average particle size is 30 μm or less, the surface roughness of the resin coating layer can be prevented from becoming excessive, the developer can be sufficiently charged, and the mechanical strength of the resin coating layer can be achieved. Can be suppressed.

  Here, the volume average particle size of the graphitized particles is specifically measured using a Coulter LS-130 type or LS-230 type particle size distribution meter (manufactured by Beckman Coulter, Inc.) of a laser diffraction type particle size distribution meter. Measured values. As measurement conditions, an aqueous module is used, and isopropyl alcohol is used as a measurement solvent. The measurement system of the particle size distribution analyzer is washed with isopropyl alcohol for about 5 minutes, and 10 to 25 mg of sodium sulfite is added to the measurement system as an antifoaming agent to execute the background function.

  Next, 3 to 4 drops of a surfactant is added to 50 ml of isopropyl alcohol, 5 to 25 mg of a measurement sample is further added, and the suspended aqueous solution is subjected to dispersion treatment for 1 to 3 minutes with an ultrasonic disperser. And The sample solution is gradually added to the measurement system of the measurement device, and the sample concentration in the measurement system is adjusted so that the PIDS on the screen of the device is 45% to 55%. Calculate the volume average particle size from the distribution.

For the purpose of improving the conductivity, coating strength and surface lubricity of the resin coating layer, the content of the graphitized particles is preferably 2 parts by mass to 150 parts by mass with respect to 100 parts by mass of the binder resin. Can mention 4 mass parts-100 mass parts.
[Surface unevenness]
Furthermore, it is preferable that the resin coating layer has an uneven surface. In order to form unevenness on the surface of the resin coating layer, it is possible to include unevenness forming particles. Examples of the material for forming the irregularities include, for example, vinyl polymers and copolymers such as polymethyl methacrylate, polyethyl acrylate, polybutadiene, polyethylene, polypropylene, polystyrene, phenol resins, polyamide resins, fluorine resins, silicone resins, polyesters. Examples thereof include resin particles such as resin, oxide particles such as alumina, zinc oxide, silicone, titanium oxide, and tin oxide, carbonized particles, and conductive particles such as resin particles subjected to conductive treatment. These concavo-convex-forming particles can also have inorganic fine powders such as metal oxides attached to their surfaces for the purpose of imparting functions such as wear resistance, conductivity, and hydrophobicity. Moreover, in order to improve the intensity | strength of a resin coating layer, the electroconductive spherical particle described in Unexamined-Japanese-Patent No. 08-240981 can also be used.

The volume resistance value of the unevenness forming particles is 10 ⁷ Ω · cm or less, more preferably 10 ⁻³ Ω · cm to 10 ⁶ Ω · cm. If the volume resistance is 10 ⁷ Ω · cm or less, it is possible to prevent the developer from adhering and fusing with the unevenness-exposed particles exposed on the surface of the resin coating layer due to abrasion as a core, and the toner particles are rapidly and uniformly distributed. Can be charged.

  Here, specific examples of the volume resistance of the irregularity-forming particles include measured values under the following conditions. A granular sample is put in an aluminum ring having a diameter of 40 mm, is pressure-molded at 2500 N, and the volume resistance value is measured by using a 4-terminal probe with a resistivity meter Loresta AP or Hiresta IP (both manufactured by Mitsubishi Yuka Co., Ltd.). taking measurement. The measurement environment is 20 ° C. to 25 ° C. and 50% RH to 60% RH.

The true density of the unevenness forming particles is more preferably ³ g / cm ³ or less. If true density of 3 g / cm ³ or less of the particles, it is possible to form a surface roughness in a small amount. Further, since the true density difference with the resin or resin composition can be reduced, it can be uniformly dispersed during production, and irregularities can be formed uniformly on the surface of the resin coating layer. Further, when the particles are spherical, the contact area with the developer regulating member or the like is reduced, so that the rotational torque of the developer carrying member due to the frictional force, the adhesion of the developer, and the like can be reduced. Specifically, as the true density of the spherical particles, a value measured by a dry density meter Accupic 1330 (manufactured by Shimadzu Corporation) can be employed.

  The unevenness-forming particles preferably have a volume average particle size of 0.3 μm to 30 μm. If the particle size of the irregularity-forming particles is 0.3 μm or more, uniform surface irregularities can be formed, the surface roughness can be increased by adding a small amount, the weakening of the resin coating layer is suppressed, A decrease in wearability can be suppressed. If it is 30 μm or less, the amount of protrusion from the surface of the resin coating layer can be made moderate, non-uniform charging of the developer and reduction of the charge amount can be suppressed, and the photoconductor when biased It can be suppressed that it becomes a leak point.

  Here, specific examples of the volume average particle diameter of the irregularity-forming particles include measurement values obtained by the same measurement method as for the graphitized particles.

  As the content of such unevenness forming particles in the resin coating layer, the surface roughness of the resin coating layer is such that the arithmetic average roughness Ra specified in JIS B0601-2001 is in the range of 0.3 μm to 3.5 μm. It is preferable that If Ra is 0.3 μm or more, the developer is appropriately transported, and it is possible to suppress the occurrence of thin image density due to lack of developer, scattering or blotch due to excessive charging of the developer. Further, when Ra is 3.5 μm or less, triboelectric charging can be uniformly applied to the developer, and the occurrence of streak unevenness, reversal fogging, and image density thin due to insufficient charging can be suppressed. As content in the resin coating layer of uneven | corrugated formation particle | grains, it can be set as 0.2 mass part-50 mass parts etc. with respect to 100 mass parts of binder resin, for example.

Here, as the value of the arithmetic average roughness Ra of the resin coating layer surface, specifically, based on the surface roughness of JIS-B0601 (2001), measurement was performed using Surfcorder SE-3500 manufactured by Kosaka Laboratory. As conditions, a cut-off of 0.8 mm, an evaluation length of 8 mm, and a feed rate of 0.5 mm / s can be measured for 3 points in the axial direction × 3 points in the circumferential direction = 9 points, and the average value can be obtained.
[Other components of resin coating layer]
Furthermore, the resin coating layer may contain a solid lubricant. Specific examples of the solid lubricant include molybdenum disulfide, boron nitride, graphite fluoride, silver-selenium niobium, calcium chloride-graphite, and talc. The amount of these solid lubricants added is preferably in the range of 1 to 100 parts by mass with respect to 100 parts by mass of the binder resin. If it is 1 mass part or more, the adhesiveness of the developer to the surface of the resin coating layer can be suppressed. If it is 100 parts by mass or less with respect to 100 parts by mass of the binder resin, the strength (abrasion resistance) of the resin coating layer is deteriorated even when a material containing a large amount of fine powder having a particle size of submicron order is used. Can be suppressed. These solid lubricants preferably have a volume average particle size of 0.2 μm to 20 μm, more preferably 1 μm to 15 μm. If the volume average particle size of the solid lubricant is 0.2 μm or more, sufficient lubricity can be obtained, and if the volume average particle size is 20 μm or less, the developer can be uniformly charged, A decrease in strength of the resin coating layer can be suppressed. Specifically, the volume average particle diameter of the solid lubricant can be a measured value by a method similar to the measuring method for the graphitized particles and the like.

As thickness of the said resin coating layer, it can select suitably, For example, it can be set as 2 micrometers-100 micrometers.
[Method of forming resin coating layer]
As a method for forming the resin coating layer, for example, each component can be dispersed and mixed in a solvent to form a paint, applied onto the substrate, and dried. For dispersion mixing of each component, a known dispersion apparatus using beads such as a sand mill, a paint shaker, a dyno mill, a pearl mill or the like can be suitably used. Moreover, as a coating method, well-known methods, such as a dipping method, a spray method, and a roll coat method, are applicable.

In order to make the content rate of the sulfur atom and nitrogen atom on the surface of the resin coating layer within the above range, it can also be achieved by appropriately selecting the addition amount of the compound having sulfur atom and nitrogen atom within the above range. It is also possible to select the type of solvent used in the coating liquid during coating formation, and to control the solid content in the coating liquid, temperature and humidity during coating, and the like. For example, as a method for increasing the ratio of the compound having a sulfur atom and a nitrogen atom existing in the vicinity of the resin coating layer surface, the following methods can be appropriately selected and adjusted by combining them.
(1) Select a highly volatile solvent (low boiling point) as the solvent used in the paint.
(2) Increase the solid concentration in the paint.
(3) High temperature / low humidity environment during coating.
(4) In the quaternary ammonium salt compound having a sulfur atom and a nitrogen atom, the alkyl group or aryl group of R1 to R4 is long in the ammonium ion formula represented by the chemical formula (A). (Increase the carbon number.)
[Other configurations of developer carrier]
In addition to the substrate and the resin coating layer, the developer carrier used in the developing device of the present invention may be provided with an elastic layer or the like between the substrate and the resin coating layer as necessary. Examples of the material for the elastic layer include rubbers such as urethane rubber, EPDM, and silicon rubber, and elastomers.
[Specific example of developer carrier]
Examples of the developer carrying member used in the electrophotographic developing method of the present invention include those shown in the schematic cross-sectional views of FIGS. The developer carrying member shown in FIG. 1 has a conductive agent b in which a resin coating layer 1 formed on a base 2 made of a metal cylindrical tube is dispersed in a binder resin a. The conductive agent b contributes to imparting conductivity to the surface of the resin coating layer 1, releasing property with respect to the toner, and imparting property to the toner.

  In the developer carrying member shown in FIG. 2, the resin coating layer 1 has solid particles c in addition to the conductive agent b dispersed in the binder resin a, and has improved surface conductivity and lubricity. . Examples of solid particles that can be used include graphitized particles and solid lubricants. Further, the solid particles c may have a function of forming irregularities on the surface of the resin coating layer.

The developer carrier shown in FIG. 3 has a spherical shape in addition to the conductive agent b and the solid particles c in which the resin coating layer 1 is dispersed in the binder resin a in order to form irregularities on the surface and control the surface roughness. The unevenness of the surface can be more easily controlled by the particle size and the addition amount of the unevenness forming particles. The developer carrying member having such a configuration is advantageous when used in a developing device including a developer layer thickness regulating member that elastically presses toner particles. Both the solid particles c and the unevenness forming particles d contribute to the formation of unevenness on the surface of the resin coating layer 2. The irregularity-forming particles d are deformed by the pressure contact force of the elastic developer regulating member to absorb the pressure applied to the binder resin, and the conductive agent c forms small irregularities so that contact charging between the toner particles and the resin coating layer is performed. It also functions to enlarge the area and adjust the releasability with the toner particles. Such a form may be applied, for example, when the irregularity-forming particles d are provided with other functions such as conductivity, charge imparting property, and wear resistance in addition to the irregularity formation.
[Developer]
Next, the developer used in the electrophotographic developing method of the present invention will be described. As the developer used in the electrophotographic development method of the present invention, a developer containing toner particles containing a binder and a magnetic substance containing magnetic iron oxide is preferable. When the toner particles have a carbon atom content A (atomic%) and an iron atom content B (atomic%) by X-ray photoelectron spectroscopy on the surface, the iron atom content relative to the carbon atom content A Preferably, the ratio B / A has a value of less than 0.001. It is preferable that the iron and iron compound released from the toner particles satisfy the formulas (4) and (5) when the liberation rate X (%).

X ≦ 3.00 (4)
−0.05X + 0.2 ≦ Y ≦ −0.3X + 1.5 (5)
[Toner particles]
The toner particles contained in the developer used in the electrophotographic development method of the present invention preferably contain a magnetic material containing a binder resin and magnetic iron oxide.
[Binder resin]
The binder resin contained in the toner particles applied to the developer may be any one that contains a magnetic material and can be integrated. Specific examples of the monomer constituting the binder resin include styrene monomers such as styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene, and p-ethylstyrene. , Methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, n-propyl acrylate, n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate , Acrylic esters such as phenyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate , Stearyl methacrylate Phenyl methacrylate, can be mentioned dimethylaminoethyl methacrylate, methacrylic acid esters such as diethylaminoethyl methacrylate and other acrylonitrile, methacrylonitrile, acrylamide. These monomers can be used alone or in admixture of two or more. Among the above-mentioned monomers, styrene or a styrene derivative is preferably used alone or in combination with other monomers from the viewpoint of developing characteristics and durability of the toner particles.

  Examples of the molecular weight of the binder resin include 10,000 to 100,000.

Furthermore, the binder resin may have a hydrophilic functional group such as an amino group, a carboxylic acid group, a hydroxyl group, a glycidyl group, or a nitrile group. Such a monomer having a hydrophilic functional group dissolves in aqueous suspension due to its water solubility and causes emulsion polymerization. Therefore, when preparing a binder resin by suspension polymerization, as a monomer component Difficult to use. For this reason, monomers having these hydrophilic functional groups (referred to as functional monomers) are polymerized in advance and added to the monomer component of the binder resin as a functional resin component for polymerization. Thus, a binder resin having these hydrophilic functional groups can be obtained. Examples of the resin component of such a functional monomer include, for example, a random copolymer of a functional monomer and a vinyl compound such as styrene or ethylene, a block copolymer, or a copolymer such as a graft copolymer. And polycondensates such as polyester and polyamide, and addition polymers such as polyether and polyimine. As content of the functional monomer in such a functional resin component, 1 mass part-20 mass parts are preferable with respect to 100 mass parts of monomers except a functional monomer. If the content of the functional monomer is 1 part by mass or more, functional group characteristics can be obtained, and if it is 20 parts by mass or less, it is possible to suppress the hindrance in designing various physical properties of the binder resin.
[Magnetic material]
The magnetic material containing magnetic iron oxide contained in the toner particles may be any as long as it contains magnetic iron oxide. Examples of magnetic iron oxide include triiron tetroxide and γ-iron oxide. As the magnetic substance, atoms such as phosphorus, cobalt, nickel, copper, magnesium, manganese, aluminum, and silicon can be used alone or in combination of two or more. These magnetic materials preferably has a BET specific surface area by nitrogen adsorption method is 2m ² / g~30m ² / g, more preferably from 3m ² / g~28m ² / g, further Mohs hardness 5-7 Are preferred.

  The shape of the magnetic material containing magnetic iron oxide includes octahedron, hexahedron, spherical shape, needle shape, scale shape, etc., but images having less anisotropy such as octahedron, hexahedron, spherical shape, and irregular shape are images. It is preferable for increasing the concentration. The shape of the magnetic body can be confirmed by SEM or the like. As the particle size of the magnetic particles, the volume average particle size is 0.1 μm to 0.3 μm, and the particles of 0.03 μm to 0.1 μm or less are 40% or less with respect to all the magnetic particles. Is preferred. When magnetic particles having a volume average particle size of 0.1 μm or more are used, the tendency of the resulting image to shift to reddish is suppressed, it has a sufficient blackness, redness in a halftone image, Insufficient image density can be suppressed. Furthermore, the dispersibility fall by the increase in the surface area of a magnetic particle can be suppressed. On the other hand, if the average particle diameter of the magnetic particles is 0.3 μm or less, it is possible to suppress the exposure to the toner particle surface due to the influence of the specific gravity difference with the binder resin as the mass per particle increases. it can. In addition, in the toner particles, if the number% of magnetic particles having a volume average particle diameter of 0.1 μm or less is 40% or less, a decrease in dispersibility caused by an increase in the surface area of the magnetic particles can be suppressed, and the toner It is possible to suppress the formation of agglomerates in the particles and suppress a decrease in chargeability of the toner particles.

  As said magnetic body, the thing by which the surface was hydrophobized is preferable. When the surface of the magnetic material is hydrophobic, uneven distribution on the toner particle surface and release from the toner particles, which are generally hydrophilic, can be substantially suppressed, and the chargeability of the toner particles is reduced. Can be suppressed. The degree of hydrophobicity of the magnetic material is preferably 50 or more.

  The degree of hydrophobicity of the magnetic material can be a value measured by a methanol titration test. Specific examples of the measurement of the degree of hydrophobicity by the methanol titration test include the following methods. 0.1 g of magnetic particles are added to 50 ml of water in a 250 ml beaker. Thereafter, methanol is gradually added to the liquid and titration is performed. In this case, methanol is preferably supplied from the bottom of the liquid and gently stirred. The point in time at which the suspended particles of the magnetic particles are no longer confirmed on the liquid surface is the end point of the sedimentation of the magnetic particles, and the volume percentage of methanol in the methanol and water mixture at this point is the hydrophobization degree.

The content of the magnetic substance in the toner particles is preferably 10 parts by mass to 200 parts by mass, and more preferably 20 parts by mass to 180 parts by mass with respect to 100 parts by mass of the binder resin. When the content of the magnetic material is 10 parts by mass or more, a sufficient coloring power can be imparted to the developer, and generation of fog can be suppressed. On the other hand, if the content of the magnetic material is 200 parts by mass or less, it is possible to suppress excessive supportability due to the magnetic force on the developer support, and to suppress a decrease in developability, as well as toner particles. It is possible to uniformly disperse the magnetic material between them.
[Method of preparing magnetic material]
The method for preparing the magnetic material containing the magnetic iron oxide is not particularly limited, but the following method can be specifically mentioned as an example.

  An aqueous solution containing ferrous hydroxide is prepared by adding an alkali such as sodium hydroxide in an amount equivalent to or greater than the iron component to the ferrous salt aqueous solution. Air is blown while maintaining the pH of this aqueous solution at 7 or higher, preferably 8 to 10, and the aqueous solution is heated to, for example, 70 ° C. or higher to oxidize ferrous hydroxide, and the core of the magnetic particles. This produces a seed crystal of iron oxide.

  Next, an aqueous solution containing about 1 equivalent of ferrous sulfate is added to the slurry-like liquid containing seed crystals based on the amount of alkali added previously. While maintaining the pH of the liquid at 6 to 10, the reaction of ferrous hydroxide proceeds while blowing air to grow magnetic particles with the seed crystal as the core. As the oxidation reaction proceeds, the pH of the liquid shifts to the acidic side, but the pH of the liquid is preferably maintained at 6 or higher.

  Ferrous sulfate, ferrous chloride, etc. can be used as the ferrous salt used in the ferrous salt aqueous solution, but the iron sulfate produced as a by-product in sulfuric acid method titanium production, along with the surface cleaning of the steel sheet By-product iron sulfate can also be used.

  Further, the concentration of the ferrous salt in the aqueous ferrous salt solution can be appropriately selected from suppressing the increase in viscosity during the reaction and the solubility of the ferrous salt. In the case of ferrous sulfate, Examples thereof include 0.5 mol / L to 2 mol / L. The ferrous salt concentration generally tends to be finer as the product is finer. The more air is used in the reaction and the lower the reaction temperature, the easier it is to atomize. Can do.

  Hydrophobizing the magnetic iron oxide of the oxidation reaction product is performed. The hydrophobization treatment is preferably performed in the state of a water-containing slurry before the magnetic iron oxide magnetic particles generated in the aqueous solution are subjected to the drying step. Or after completion | finish of an oxidation reaction, it is preferable to carry out in the state re-dispersed in another aqueous medium, without drying the magnetic body particle obtained by washing | cleaning and filtering. When the magnetic particles before the hydrophobization treatment are dried, the magnetic particles cannot be agglomerated with each other, and it is difficult to perform the uniform hydrophobization treatment even if the wet magnetic hydrophobic treatment is performed on the aggregated magnetic particles. .

  As a method for hydrophobizing a magnetic material containing magnetic iron oxide, the pH of the magnetic material in an aqueous medium is adjusted, and the coupling agent is dispersed while sufficiently stirring and dispersing so that the magnetic particles containing magnetic iron oxide become primary particles. Surface treatment is performed while hydrolyzing. Thereafter, a method of obtaining hydrophobized magnetic particles by lightly crushing after filtration / drying is preferred. In such a hydrophobizing method of a magnetic substance in an aqueous phase, aggregation of magnetic particles is less likely to occur than in a conventional hydrophobizing process in a gas phase, and between magnetic particles by a hydrophobizing process. Due to the charge repulsion action, a magnetic body in the form of primary particles whose surface is almost hydrophobized can be obtained. Further, in such a hydrophobizing method, it is not necessary to use a coupling agent that generates a gas, such as chlorosilanes and silazanes, and it is difficult due to aggregation of magnetic particles in the gas phase. The high-viscosity coupling agent that was used can also be used. Thus, by the hydrophobizing method in the aqueous phase, a magnetic material excellent in hydrophobicity and dispersibility that cannot be achieved by the conventional hydrophobizing method in the gas phase can be obtained.

  Examples of the coupling agent used in the hydrophobic treatment method include a silane coupling agent and a titanium coupling agent. As this silane coupling agent, what is shown by a formula (B) is preferred.

_{R m -Si-Y n (B} )
In the formula, R represents an alkoxy group, m represents an integer of 1 to 3, Y represents a hydrocarbon group such as an alkyl group, vinyl group, glycidoxy group, or methacryl group, and n represents an integer of 1 to 3. Show. Specifically, for example, vinyltrimethoxysilane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane, methyltrimethoxysilane, methyltriethoxysilane, isobutyltrimethoxysilane, dimethyldimethoxysilane, dimethyl Examples include diethoxysilane, trimethylmethoxysilane, hydroxypropyltrimethoxysilane, phenyltrimethoxysilane, n-hexadecyltrimethoxysilane, and n-octadecyltrimethoxysilane.

  In particular, an alkyltrialkoxysilane coupling agent represented by the formula (C) can be mentioned as a preferred coupling agent.

_{C p H 2p + 1 -Si- (} OC q H 2q + 1) 3 (C)
In the formula, p represents an integer of 2 to 20, and q represents an integer of 1 to 3. When p in the formula (C) is 2 or more, the hydrophobic treatment can be easily performed sufficiently, and the exposure of the magnetic substance from the toner particles can be suppressed. If p is 20 or less, sufficient hydrophobicity and aggregation of the magnetic particles can be suppressed, and uniform dispersion of the magnetic particles in the toner particles can be obtained at the same time. It can have transferability and selective developability. Moreover, if q is 3 or less, it can suppress the fall of the reactivity of a silane coupling agent, and can fully hydrophobize. In particular, p in the formula represents any integer of 2 to 20, more preferably any integer of 3 to 15, and q is any integer of 1 to 3, more preferably 1 or 2. The alkyltrialkoxysilane coupling agent showing an integer can remarkably obtain the above effects.

  The amount of the silane coupling agent used in the hydrophobization treatment is preferably 0.05 parts by mass to 20 parts by mass with respect to 100 parts by mass of the magnetic powder, more preferably 0. 1 part by mass to 10 parts by mass.

  As the aqueous medium for hydrophobizing the magnetic material, water containing various additives in addition to water can be used as long as it is a medium containing water as a main component. Examples of the additive include a surfactant, a pH adjuster, and an organic solvent. The surfactant is preferably a nonionic surfactant such as polyvinyl alcohol, and the amount added is preferably 0.1% by mass to 5% by mass with respect to water. As the pH adjuster, an inorganic acid such as hydrochloric acid can be used.

  The stirring is performed by using, for example, a mixer having a stirring blade, specifically, a high shearing force mixing device such as an attritor or a TK homomixer, and suppressing the aggregation of the magnetic particles in the aqueous medium. It is preferable that the rotation speed is such that it is dispersed.

The hydrophobized magnetic material thus obtained has no aggregation of particles, and the surface of each particle is uniformly hydrophobized, so the dispersibility to the binder resin is very good, and it should be used as a developer. Thus, a magnetic developer excellent in image characteristics can be obtained.
[Other contents of toner particles]
The toner particles preferably contain a release agent (wax component). Specific examples of such wax include petroleum wax such as paraffin wax, microcrystalline wax, petrolactam and derivatives thereof, montan wax and derivatives thereof, hydrocarbon wax and derivatives thereof by Fischer-Tropsch method, and polyolefins represented by polyethylene. Examples thereof include waxes and derivatives thereof, natural waxes such as carnauba wax and candelilla wax, and derivatives thereof. Derivatives here include oxides, block copolymers with vinyl monomers, graft modified products, and the like. Furthermore, fatty acids such as higher aliphatic alcohols, stearic acid and palmitic acid or compounds thereof, acid amide waxes, ester waxes, ketones, hydrogenated castor oil and derivatives thereof, vegetable waxes and animal waxes can also be used.

  The content of the wax component is preferably in the range of 0.5 to 50 parts by mass with respect to 100 parts by mass of the binder resin. If the content of the wax component is 0.5 parts by mass or more, the toner particles have sufficient releasability, and if it is 50 parts by mass or less, they have stability even after long-term storage. It is possible to suppress an adverse effect on the dispersibility of the toner material and a decrease in toner fluidity and image characteristics.

In addition, a charge control agent for controlling the charged property may be added to the toner particles. As the charge control agent, one that has a high charge speed and can stably maintain a constant charge amount can be used. In the case of toner particles obtained by the direct polymerization method, when added to a polymerization solution, it is particularly preferable that the polymerization inhibition property is low and the toner is insoluble in an aqueous dispersion medium. Specific examples include metal compounds of aromatic carboxylic acids such as salicylic acid, alkyl salicylic acid, dialkyl salicylic acid, naphthoic acid, and dicarboxylic acid, metal salts or metal complexes of azo dyes or azo pigments, sulfonic acid or carboxylic acid groups in the side chain. And polymer compounds, boron compounds, urea compounds, silicon compounds, calixarene and the like. The amount of the charge control agent used can be selected depending on the type of the binder resin, the presence or absence of other additives, and the toner particle production method including the dispersion method, and is not uniquely limited. For example, it can be 0.1-10 mass parts with respect to 100 mass parts of binder resin. More specifically, the range of 0.1 mass part-5 mass parts can be mentioned.
[Content of iron atoms on the surface of toner particles]
In the toner particles, when the carbon atom content A (atomic%) and iron atom content B (atomic%) by surface X-ray photoelectron spectroscopy analysis, the iron atom content relative to the carbon atom content A is included. Preferably, the ratio B / A has a value of less than 0.001. If the ratio B / A of the content ratio of iron atoms to the content ratio A of carbon atoms is less than 0.001, the magnetic substance is not substantially exposed on the toner particle surface. For this reason, it is possible to suppress the influence of moisture absorption of the magnetic material or the magnetic material from being excessive as a charge leak site, and to suppress the occurrence of deterioration in development characteristics due to the charge escaping from the toner particles. Can do. In particular, under high temperature and high humidity conditions, it is possible to suppress the occurrence of fogging and image density reduction due to use, thereby improving toner particle fluidity and tribocharging properties, especially development characteristics such as no fogging. Can be achieved.

Here, as the content of iron atoms and carbon atoms on the toner particle surface by X-ray photoelectron spectroscopic analysis, a measurement value based on the same method and conditions as the method for analyzing atoms on the surface of the resin coating layer can be employed. Prior to the measurement, it is preferable to perform the measurement after washing the toner particles with a solvent that does not dissolve the toner particles, for example, isopropyl alcohol, and removing external additives in the hydrophobic treatment existing on the toner particle surface. .
[Particle size of toner particles]
Further, the particle diameter of the toner particles preferably has a weight average particle diameter of 3 μm to 10 μm in order to enable high-quality image formation in which finer latent image dots are faithfully developed. If the weight average particle diameter is 3 μm or more, it is possible to suppress an increase in the amount of residual toner particles on the photoconductor due to a decrease in transfer efficiency, and the photoconductor is scraped or fused in the contact charging process. Can be suppressed. Thereby, an increase in the surface area of the entire toner particles can be suppressed, a decrease in fluidity and agitation as a powder can be suppressed, and non-uniform charging can be suppressed among the toner particles. Further, fog and transferability can be prevented from being lowered, and image unevenness due to photoconductor scraping and toner particle fusion can be suppressed. Moreover, if a weight average particle diameter is 10 micrometers or less, scattering of a character and a line image can be suppressed and high resolution can be obtained.

As the weight average particle diameter and particle size distribution of the toner particles, measured values by the following measuring method can be adopted. Examples of the method for measuring the weight average particle diameter of the toner particles include a Coulter counter method using a Coulter counter TA-II, Coulter Multisizer II, Coulter Multisizer III (all manufactured by Beckman Coulter, Inc.) and the like. . As the electrolytic solution, a 1% NaCl aqueous solution is prepared using primary sodium chloride. For example, ISOTON R-II (manufactured by Beckman Coulter) can be used. As a measurement method, 0.1 ml to 5 ml of a surfactant (preferably alkylbenzene sulfonate) is added as a dispersant to 100 ml to 150 ml of this electrolytic aqueous solution, and 2 mg to 20 mg of a measurement sample is further added. The electrolytic solution in which the sample is suspended is dispersed 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 above measuring apparatus. The volume distribution and the number distribution are calculated. The weight-based weight average particle diameter (D4) obtained from the volume distribution (the median value of each channel is used as a representative value for each channel) 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; 13 channels of less than 40 μm; 25.40 to less than 32.00 μm; 32.00 to less than 40.30 μm can be used.
[Toner particle circularity]
The toner particles have an average circularity of 0.970 or more in toner particles (circle equivalent toner particles) having an equivalent circle diameter of 3 μm or more and 400 μm or less measured by a flow type particle image measuring apparatus. Is preferred. This is because by increasing the average circularity in this way, it becomes easy to frictionally charge individual toner particle surfaces uniformly, and the charging uniformity is excellent. The average circularity of the toner particles is used as a simple method for quantitatively expressing the particle shape.

  Specifically, the average circularity of the toner particles is measured using a flow type particle image analyzer “FPIA-1000” manufactured by Toago Medical Electronics Co., Ltd. The circularity (Ci) is calculated by the calculation formula (8).

Circularity (Ci) = perimeter of a circle having the same projected area as the number of particles
÷ Perimeter of projected image of particle (8)
Furthermore, a value obtained by dividing the sum of the circularity of all particles measured by the calculation formula (9) by the total number of particles can be used as the average circularity.

上記フロー式粒子像分析装置においては、各粒子の円形度を算出し、円形度を一定間隔で分割した領域に属する粒子数によって、平均円形度及びモード円形度を算出し、平均円形度を算出する。具体的には、円形度０．４０〜１．００を０．０１０間隔で６１分割した各領域の中心値と、その領域に属する粒子数、即ち頻度を用いて平均円形度の算出を行なう。この算出法で算出される平均円形度と、計算式（９）によって算出される平均円形度（Ｃ）との誤差は、微小であり、実質的には無視できる程度のものである。このため、上述のように計算式（９）により求めた値を、粒子の凹凸の度合いの指標として用いて差し支えないことが分かる。ここで、円形度としては粒子が完全な球形の場合１．０００を示し、表面形状が複雑になるほど平均円形度は小さな値となる。

In the flow type particle image analyzer, the circularity of each particle is calculated, the average circularity and the mode circularity are calculated based on the number of particles belonging to the region obtained by dividing the circularity at a constant interval, and the average circularity is calculated. To do. Specifically, the average circularity is calculated using the center value of each region obtained by dividing the circularity of 0.40 to 1.00 by 61 at intervals of 0.010 and the number of particles belonging to the region, that is, the frequency. The error between the average circularity calculated by this calculation method and the average circularity (C) calculated by the calculation formula (9) is very small and practically negligible. For this reason, it turns out that the value calculated | required by the formula (9) as mentioned above may be used as a parameter | index of the degree of unevenness | corrugation of particle | grains. Here, the circularity is 1.000 when the particles are perfectly spherical, and the average circularity becomes smaller as the surface shape becomes more complicated.

As a specific method for measuring the circularity of the toner particles, the method described in the FPIA-1000 catalog (June 1995 edition) can be used. As such a method, about 5 mg of a developer is dispersed in 10 ml of an aqueous solution of about 0.1 mg of a surfactant, and ultrasonic waves (20 kHz, 50 W) are irradiated for 5 minutes to obtain 5000 toner particles / μL to 20,000 particles / μL. Prepare a sample dispersion containing. The sample dispersion is passed through a flow path (spread along the flow direction) of a flat and flat flow cell (thickness: about 200 μm). A strobe and a CCD camera are arranged on opposite sides so as to form an optical path intersecting with the thickness of the flow cell, and the particles flowing through the flow cell are irradiated at 1/30 second intervals. The particles are photographed as a two-dimensional image having a certain range parallel to the flow cell. From the two-dimensional image of each particle, the diameter of a circle having the same area is calculated as the equivalent circle diameter from the projected area. Further, the perimeter is obtained, and the circularity is calculated as described above. Here, the reason for measuring the circularity of the equivalent toner particles of 3 μm or more and 400 μm or less is as follows. The group of particles having an equivalent circle diameter of less than 3 μm or more than 400 μm contains many particles other than toner particles, and there are few particles other than toner particles having an equivalent circle diameter of 3 μm or more and 400 μm or less. When the circularity is used, the error is small.
[Method for producing toner particles]
Examples of the method for producing the toner particles include a pulverization method and a polymerization method. As a pulverization method, components necessary as a toner such as the binder resin, magnetic material, release agent, other charge control agent, colorant, and other additives are sufficiently mixed by a mixer such as a Henschel mixer or a ball mill. Thereafter, melt kneading using a heat kneader such as a heating roll, a kneader, an extruder, etc., cooling solidification, pulverization, classification, and a method of performing surface treatment as necessary can be mentioned. Either the classification or the surface treatment may be performed first. In the classification step, it is preferable to use a multi-division classifier for improving production efficiency. In the pulverization step, a known pulverization apparatus such as a mechanical impact type or a jet type can be used.

  In order to obtain toner particles having a specific degree of circularity, a process of further pulverizing by applying heat or applying a mechanical impact as an auxiliary can be mentioned. Further, a hot water bath method in which finely pulverized (classified as necessary) toner particles are dispersed in hot water, a method of passing in a hot air stream, or the like can be used. Specific examples of means for applying the mechanical impact force include the following devices. Examples thereof include a kryptron system manufactured by Kawasaki Heavy Industries, Ltd., a mechanical impact pulverizer such as a turbo mill manufactured by Yuichi Bo Kogyo Co., Ltd., a mechano-fusion system manufactured by Hosokawa Micron Co., a hybridization system manufactured by Nara Machinery Co., Ltd., and the like. In the hybridization system, a method is adopted in which toner particles are pressed against the inside of a casing by centrifugal force with a blade rotating at high speed, and mechanical impact force is applied to the toner particles by force such as compression force or friction force. In the mechanical impact method, a thermomechanical impact in which the treatment temperature is a temperature (Tg ± 10 ° C.) in the vicinity of the glass transition point (Tg) of the magnetic toner particles is preferable from the viewpoint of preventing aggregation and productivity. More preferably, it is particularly effective to improve the transfer efficiency to carry out at a temperature in the range of glass transition point (Tg) ± 5 ° C. of the magnetic toner particles.

  As a method for producing the toner particles, in order to make the content of iron atoms on the surface specific, a polymerization method is preferable, and a suspension polymerization method is more preferable. In this suspension polymerization method, a polymerizable monomer constituting a binder resin, a magnetic substance, and, if necessary, a colorant, a polymerization initiator, a crosslinking agent, a charge control agent, and other additives are added to an aqueous medium. A polymerizable monomer composition is obtained by uniformly dissolving or dispersing. Thereafter, the polymerizable monomer composition is dispersed in a continuous layer (for example, an aqueous phase) containing a dispersion stabilizer by using a suitable stirrer, and simultaneously subjected to a polymerization reaction, whereby toner particles having a desired particle size are obtained. Is the way to get Since the magnetic material is generally hydrophilic, it is preferable to use a magnetic material that has been previously subjected to a surface treatment such as the hydrophobic treatment. By subjecting the hydrophilic magnetic material to surface treatment such as hydrophobic treatment, it is possible to suppress uneven distribution on the surface of the toner particles or in a state of being easily released from the toner particles.

  As the polymerization initiator, those having a half-life of 0.5 hours to 30 hours during the polymerization reaction are preferable. Specifically, 2,2′-azobis- (2,4-dimethylvaleronitrile), 2,2′-azobisisobutyronitrile, 1,1′-azobis (cyclohexane-1-carbonitrile), 2 , 2′-azobis-4-methoxy-2,4-dimethylvaleronitrile, azobisisobutyronitrile and other azo or diazo polymerization initiators; benzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxycarbonate, cumene hydro Examples thereof include peroxide-based polymerization initiators such as peroxide, 2,4-dichlorobenzoyl peroxide, lauroyl peroxide. The amount of the polymerization initiator used is 0.5 to 20% by mass relative to the polymerizable monomer, and a polymer having a maximum between 10,000 and 100,000 can be obtained. It is preferable because preferable strength and melting characteristics can be imparted to the particles.

  Specific examples of the crosslinking agent include aromatic divinyl compounds such as divinylbenzene and divinylnaphthalene; diacrylate compounds linked by an alkyl chain such as ethylene glycol diacrylate and 1,3-butylene. Glycol diacrylate, 1,4-butanediol diacrylate, 1,5-pentanediol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, and acrylates of the above compounds are replaced with methacrylate Can be mentioned. Examples of the polyfunctional cross-linking agent include pentaerythritol triacrylate, trimethylol ethane triacrylate, trimethylol propane triacrylate, tetramethylol methane tetraacrylate, oligoester acrylate, and those obtained by replacing acrylate of the above compounds with methacrylate; Examples include allyl cyanurate and triallyl trimellitate. As the usage-amount of a crosslinking agent, 0.001 mass%-15 mass% of a polymerizable monomer can be mentioned.

  As a method for polymerizing toner particles, specifically, the above polymerizable monomer is mixed with a magnetic material, if necessary, a colorant, a release agent, a plasticizer, a binder, a charge control agent, a crosslinking agent, a polymerization agent. In order to reduce the viscosity of the polymer produced by the reaction, an organic solvent, a dispersant and the like are added as appropriate, and a monomer system is prepared using a disperser. As the disperser, a homogenizer, a ball mill, a colloid mill, an ultrasonic disperser, or the like can be used. The monomer system thus obtained is dispersed / suspended in an aqueous medium containing a dispersion stabilizer. At this time, it is preferable to use a high-speed disperser such as a high-speed stirrer or an ultrasonic disperser at a stretch to obtain a desired toner particle size because the particle size distribution of the obtained toner particles becomes sharp. The polymerization initiator may be added at the same time when other additives are added to the monomer, or may be added immediately before the monomer system is dispersed in the aqueous medium. Further, immediately after the monomer system is dispersed in the aqueous medium, a polymerization initiator dissolved in the monomer or solvent may be added before the polymerization reaction is started.

  As the dispersion stabilizer, a surfactant or an organic / inorganic dispersant can be used. Among them, the inorganic dispersant can suppress the generation of harmful ultrafine powder, and the dispersion stability is obtained by steric hindrance, so that it can be prevented from becoming unstable even when the reaction temperature changes, and cleaning is easy. This is preferable because adverse effects on the toner particles can be suppressed. Specific examples of inorganic dispersants include polyvalent metal phosphates such as calcium phosphate, magnesium phosphate, aluminum phosphate, and zinc phosphate; carbonates such as calcium carbonate and magnesium carbonate; calcium metaoxalate, calcium sulfate, and barium sulfate. And inorganic oxides such as calcium hydroxide, magnesium hydroxide, aluminum hydroxide, silica, bentonite, and alumina. These can be used alone or in combination of two or more.

  As the usage-amount of these inorganic dispersing agents, 0.2 mass part-20 mass parts in total are preferable with respect to 100 mass parts of monomers. When producing more finely divided toner particles having an average particle diameter of 5 μm or less, 0.001 to 0.1 parts by mass of a surfactant can be used in combination.

  Specific examples of the surfactant include sodium dodecylbenzene sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, sodium oleate, sodium laurate, sodium stearate, and potassium stearate.

  In the case of using these inorganic dispersants, a method of directly adding the inorganic dispersant to the aqueous medium can be mentioned, but the inorganic dispersant particles of the reaction product formed as fine particles by reaction in the aqueous medium can be mentioned. Including reaction systems can be used. For example, a sodium phosphate aqueous solution and a calcium chloride aqueous solution are mixed under high-speed stirring to produce water-insoluble calcium phosphate as fine particles. By using an aqueous dispersion containing calcium phosphate as fine particles as the water-insoluble product as an inorganic dispersant, toner particles can be dispersed more uniformly and finely. At this time, a sodium chloride salt of a water-soluble by-product is produced as a by-product at the same time. However, when a water-soluble salt is present in the aqueous medium, dissolution of the monomer in water is suppressed, and ultrafine particles based on emulsion polymerization are used. Since the generation of toner particles is suppressed, it is more convenient. When the residual monomer is removed at the end of the polymerization reaction, a by-product becomes an obstacle. Therefore, it is preferable to replace the aqueous medium or desalinate with an ion exchange resin. The inorganic dispersant can be almost completely removed by dissolution with an acid or alkali after completion of the polymerization.

  In such a polymerization reaction, the polymerization temperature can be set to 40 ° C. or higher, and can be set to, for example, 50 ° C. to 90 ° C. When the polymerization is carried out in this temperature range, the release agent and waxes to be sealed inside can be precipitated by phase separation to make the encapsulation more complete. In order to consume the remaining monomer, the reaction temperature can be set to 90 ° C. to 150 ° C. at the end of the polymerization reaction.

After the polymerization, the toner particles can be filtered, washed and dried by a known method. Furthermore, it is also preferable to perform classification thereafter to remove coarse powder and fine powder.
[Free iron and iron compounds]
In the developer used in the electrophotographic development method of the present invention, it is preferable that the iron and iron compound liberated from the toner particles satisfy the formulas (4) and (5) when the liberation rate X (%).

X ≦ 3.00 (4)
−0.05X + 0.2 ≦ Y ≦ −0.3X + 1.5 (5)
There is a correlation between the release rate of iron and iron compounds released from the toner particles and the exposure amount of the magnetic material to the toner particle surface, and the release rate of the magnetic material is 3.00% or less, preferably 1.00% or less. If so, exposure of the magnetic material to the surface of the toner particles is generally suppressed, and a high charge amount of the toner particles can be imparted. Here, the liberation rate of iron and iron compound is defined as the iron and iron compound released from the toner particles with respect to the total number of iron atoms of the iron and iron compound contained in the toner particles and the iron and iron compound released from the toner particles. Represents the ratio of the number of atoms. The release rate of iron and iron compounds from toner particles depends on the degree of hydrophobicity of the magnetic material, compatibility with the binder resin, particle size distribution, processing uniformity, etc., but the surface of the magnetic material becomes hydrophobic. When the treatment is uneven or insufficient, the magnetic substance tends to be present on the toner particle surface, and a part or all of the magnetic substance is released. For this reason, the charge amount of toner particles tends to increase as the liberation rate of iron and iron compounds decreases. When the liberation rate is 3.00% or less, the charge leak point does not increase, and the decrease in the charge amount of the magnetic toner can be suppressed. This tendency becomes particularly remarkable under high temperature and high humidity. Further, if the decrease in charge amount can be suppressed, an increase in fog and a decrease in image quality can be suppressed.

  Further, in the developer, the ratio Y of the sulfur atom content S (1) (atomic%) and the nitrogen atom content N (atomic%) by X-ray photoelectron spectroscopic analysis on the surface of the resin coating layer of the developer carrier Y = It is preferable that S (1) / N and the liberation rate X (%) of iron and iron compound released from the toner particles satisfy the formula (5).

−0.05X + 0.2 ≦ Y ≦ −0.3X + 1.5 (5)
By satisfying such a relationship, the developer not only has excellent development characteristics, but also has a sufficient inhibitory effect on the decrease in developability associated with charge-up of the developer, particularly in a low humidity environment. It can be demonstrated.

  Here, the liberation rate of iron and iron compound liberated from the toner particles can be measured by the following measuring method. As a method for measuring the liberation rate of iron and iron compound of the magnetic toner, a particle analyzer (PT1000: manufactured by Yokogawa Electric Corporation) is used and is based on the principle described on pages 65-68 of Japan Hardcopy 97 papers. The particle analyzer can introduce fine particles such as toner particles one by one into the plasma and detect the atom, number of particles, and particle size of the luminescent material from the emission spectrum of the fine particles. With this device, the number of light emissions in which the light emission of carbon atoms and the light emission of iron atoms, which are constituent atoms of the binder resin, are detected simultaneously and the number of light emission times of iron atoms are detected. It can be the liberation rate of the compound.

Free rate of iron and iron compound (%) = 100 × {number of light emission of iron atom only /
(Number of light emission of iron atom emitted simultaneously with carbon atom + Number of light emission of iron atom only)}
Here, simultaneous emission of carbon and iron atoms means simultaneous emission of iron atoms emitted within 2.6 msec from emission of carbon atoms, and subsequent emission of iron atoms counted as emission of only iron atoms. To do. Since toner particles contain a relatively large amount of magnetic substance, simultaneous emission of carbon atoms and iron atoms can be regarded as a state in which toner particles contain magnetic substances. Light emission can be understood as being in a state where the magnetic material is released from the toner particles.

The specific measurement method is as follows. Measurement is performed in an environment of 60% humidity at 23 ° C. using helium gas containing 0.1% oxygen, and the toner particle sample is left to stand overnight in the same environment and used for measurement. Also, channel 1 measures carbon atoms (measurement wavelength 247.860 nm, K factor uses recommended value), and channel 2 measures iron atoms (measurement wavelength 239.56 nm, K factor uses 3.3964). In this scan, sampling is performed so that the number of light emission of carbon atoms is 1000 to 1400, and the scan is repeated until the total number of light emission of carbon atoms reaches 10,000 or more, and the number of light emission is integrated. In this case, in the distribution in which the number of light emission of carbon atoms is taken on the vertical axis and the cube root voltage of the carbon atom is taken on the horizontal axis, the distribution is sampled so that the distribution has one maximum and no valley exists. And measure. Based on this data, the noise cut level of all atoms is set to 1.50 V, and the liberation rate of iron and iron compound is calculated using the above formula.
[Developer content]
The developer used in the electrophotographic development method of the present invention may contain a fluidity improver and other external additives as required, in addition to the toner particles.

  The fluidity improver is one that adheres to the surface of the toner particles and improves the fluidity of the toner particles, and is preferably an inorganic fine powder or a hydrophobic inorganic fine powder. Examples of the inorganic fine powder or the hydrophobic inorganic fine powder include titanium oxide fine powder, silica fine powder, and alumina fine powder. Among these, silica fine powder can be mentioned as a preferable one. As the silica fine powder, both a so-called dry method produced by vapor phase oxidation of a silicon halogen compound, a so-called wet silica produced from water glass or the like, and dry silica called fumed silica can be used. Of these, dry silica is preferred because it has few silanol groups on the surface and inside and no production residue.

The inorganic fine powder specific surface area according to the measured nitrogen adsorption by the BET method of more than 30 m ² / g, in particular 50m ² / g~400m ² / g in the range of it is possible to obtain a fluidity improving effect ,preferable.

  Further, the silica fine powder is preferably hydrophobized because of its characteristics in a high temperature and high humidity environment. Hydrophobic treated silica fine particles are suppressed in moisture absorption, and therefore, it is possible to suppress a decrease in the charge amount of the toner particles and, in turn, a decrease in image density. Examples of the method for hydrophobizing silica fine particles include chemical treatment of an organosilicon compound that reacts or physically adsorbs with silica fine powder. Specifically, organosilicic compounds such as silicone oil after hydrophobizing a dry silica fine powder produced by vapor phase oxidation of a silicon halogen compound with a silane coupling agent or simultaneously with a hydrophobizing treatment with a silane coupling agent The method of hydrophobizing can be mentioned.

Further, as an external additive contained in the developer, for example, it is added for the purpose of improving cleaning properties, etc., and it is spherical with fine particles having a primary particle size of more than 30 nm and preferably a specific surface area of less than 50 m ² / g. There may be mentioned near inorganic fine particles or organic fine particles. As such fine particles, the primary particle diameter is preferably 50 nm or more, and the specific surface area is more preferably less than 30 m ² / g. For example, spherical silica particles or spherical resin particles are preferably used.

  Further, as other additives, a small amount of a lubricant powder, an abrasive, an anti-caking agent, a conductivity-imparting agent, organic particles with reverse polarity, inorganic fine particles and the like can be added as a developability improver. Examples of the lubricant powder include fluororesin powder, zinc stearate powder, and polyvinylidene fluoride powder. Examples of the abrasive include cerium oxide powder, silicon carbide powder, strontium titanate powder, and strontium silicate powder. Examples of the conductivity imparting agent include carbon black powder, zinc oxide powder, tin oxide powder and the like. These additives can also be used after hydrophobizing the surface.

The amount of these additives used is preferably in a range that does not hinder the function of the toner particles, and may be, for example, 0.05 parts by mass to 5 parts by mass with respect to 100 parts by mass of the toner particles. Specifically, it can be in a range of 0.1 to 4 parts by mass.
[Method for Preparing Developer]
Examples of a method for preparing such a developer include a method in which these additives are mixed with toner particles by appropriately heating and stirring.
[Specific examples of developing device]
As an example of an electrophotographic developing apparatus to which the electrophotographic developing method of the present invention is applied, a non-contact developing type developing apparatus using a one-component magnetic developer shown in FIG. 4 can be specifically mentioned. The electrophotographic developing apparatus shown in FIG. 4 mainly includes a developing container 603, a developer carrier 610, and a developer layer thickness regulating member 602. The developer carrying member 610 is provided with a developing sleeve 608 having a resin coating layer 607 coated on a metal cylindrical tube 606 as a base, and a magnet roller 609 made of a magnetic material provided coaxially in the developing sleeve. It is done. A developer layer thickness regulating member 602 made of a ferromagnetic metal is provided facing the developing sleeve 608 while maintaining a gap of 50 μm to 500 μm. Further, the developing sleeve rotating in the direction of the arrow A is disposed so as to face the photosensitive member 601 rotating in the direction of the arrow B with a slight gap in the developing region D.

  The developing container 603 is provided with a first chamber 614 and a second chamber 615 divided by a partition member 604, and the first chamber 614 and the second chamber 615 are provided from a developer supply container (not shown) via a developer supply member (such as a screw) 612. A magnetic developer is fed into the chamber 614. A stirring / conveying member 605 is provided in the first chamber 614 so that the magnetic developer supplied to the first chamber 614 passes through the gap between the partition member 604 and the inner wall of the developing container and is sent to the second chamber 615. It has become. A stirring member 611 is provided in the second chamber 615 so as to suppress the retention of the developer. The magnetic developer supplied to the second chamber 615 is carried on the developing sleeve 608 by the action of the magnetic force of the magnet roller 609, and the electrostatic latent image on the photosensitive member is caused by friction between the toner particles and the resin coating layer 607. The triboelectric charge required for the development is applied. Further, when magnetic lines of force from the magnetic pole N1 of the magnet roller 609 are concentrated on the developer regulating member 602, a thin layer of magnetic developer is formed on the developing sleeve 608, and when the developing sleeve rotates, the magnetic developer is developed. It is transported to the area D. The thin layer of magnetic developer formed on the developing sleeve 608 has a thickness that is even thinner than the minimum gap between the developing sleeve 608 and the photoreceptor 601 in the developing region D.

  A developing bias voltage is applied to the developing sleeve 608 by a developing bias power source 613. When a DC voltage is used as the developing bias voltage, a value between the potential of the electrostatic latent image visualized by the magnetic developer adhering to the developing sleeve and the potential of the background portion not adhering to the magnetic developer. It is preferable to apply a voltage of Further, in order to increase the density of the developed image and improve the gradation, an alternating bias voltage may be applied to the developing sleeve 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 an alternating bias voltage in which a DC voltage component having a value intermediate between the potential of the electrostatic latent image and the potential of the background portion is superimposed. By applying such a bias voltage, the one-component developer having magnetic toner particles carried on the developing sleeve flies in the developing region D and adheres to the electrostatic latent image on the photoreceptor. .

  As another example of the electrophotographic developing apparatus to which the electrophotographic developing method of the present invention is applied, a non-contact developing type developing apparatus using a one-component magnetic developer shown in FIG. 5 can be specifically mentioned. . The developing device shown in FIG. 5 is provided with a developer regulating member 616 arranged at a position in contact with the developing sleeve. The developer regulating member 616 is made of a rubber elastic material such as urethane rubber or silicone rubber, or an elastic plate made of a metal elastic material such as phosphor bronze or stainless steel. It is arranged in contact or pressure contact via. The contact pressure of the developer layer thickness regulating member 616 with respect to the developing sleeve 608 is a linear pressure of 5 g / cm to 50 g / cm so that the magnetic developer can be stably frictionally charged, and the magnetic developer on the developing sleeve It is preferable because the layer thickness can be suitably formed. If the contact pressure of the developer layer thickness regulating member 616 is a linear pressure of 5 g / cm or more, a thin layer of magnetic developer can be formed on the developing sleeve with a uniform thickness. This can be suppressed. If the contact pressure of the developer layer thickness regulating member 616 is 50 g / cm or less of linear pressure, the magnetic developer is prevented from being broken by pressing, and the developer is deteriorated or the developer is fused to the developing sleeve or the developer regulating member. Can be prevented from sticking.

  The magnetic developer thus formed as a thin layer on the developing sleeve and appropriately frictionally charged is conveyed to the developing region D as the developing sleeve rotates and adheres to the electrostatic latent image on the photoreceptor 601. Thus, a toner image is formed.

  In such a developing device that contacts or presses the developer layer thickness regulating member, the resin coating layer 607 on the surface of the developing sleeve 608 has a developer layer thickness regulating member 602 and a developing sleeve 608 as shown in FIG. Compared with developing devices with gaps, the load is large and generally subject to wear due to friction, but in the present invention, wear can be reduced even in such a system, so it has excellent durability. Excellent charge imparting ability.

4 and 5 is merely an example of an electrophotographic developing apparatus to which the electrophotographic developing method of the present invention is applied. The developer layer thickness regulating member, the shape of the developing container 603 (hopper), the stirring blade 605, The presence / absence of 611, the arrangement of magnetic poles, the shape of the developer supply member 612, and the presence / absence of a supply container are not limited thereto.
[Process cartridge]
The process cartridge of the present invention is detachable from the main body of the electrophotographic apparatus, and can use the electrophotographic developing method of the present invention. An example is shown in FIG. The process cartridge shown in FIG. 7 includes a developing device, a photoreceptor 51, a charging device 73, a cleaning blade 72a, and the like, which are integrally formed and detachable from the main body of the electrophotographic apparatus. The developing device of such a process cartridge is provided with a developing container 53 containing a magnetic developer as a one-component developer and having an opening, and a developer carrier 58 having a magnet roller mounted therein. Further, a developer layer thickness regulating member 67 is provided for returning excess developer from the surface of the developer carrying member to the developing container and charging the toner particles passing between the developer carrying member and the developer carrying member. The developer carrying member is installed so as to close the opening of the developing container and expose a part thereof, and has a developing region facing the photosensitive member in the exposed part.

  The developer T put in the developer container 53 of the developing device is supplied to the developer carrier 58, and the developer carried on the developer carrier 58 is adjusted to a certain amount by the developer layer thickness regulating member 67. . On the other hand, an electrostatic latent image is formed by laser light on the photosensitive member 51 charged by the charging device 73, and the electrostatic latent image is developed and visualized by adhesion of the developer supplied by the developer carrier 58. The developer attached to the photoconductor 51 is transferred onto a recording material (not shown) such as paper, and the residual developer on the photoconductor 51 is scraped off by a cleaning blade 72a and dropped into a waste toner container 72. It has become.

The electrophotographic apparatus to which the process cartridge of the present invention can be applied may be any one of a copying machine, a facsimile, a printer, and the like.
[Electrophotographic equipment]
The electrophotographic apparatus of the present invention can use the electrophotographic developing method of the present invention, and a preferred example is shown in FIG. In the electrophotographic apparatus shown in FIG. 8, a charging device 131 is used to charge the surface of the photosensitive drum as the latent image carrier 110, and the exposure system 132 performs image exposure on the photosensitive drum 110 to form a latent image. . Then, the latent image is developed in the developing device 111 including the developing sleeve 115 including the magnet 116 and the developer layer thickness regulating member 117 that regulates the layer thickness of the developer on the developing sleeve 115, and is on the photosensitive drum. A toner image is formed on the surface. Here, an alternating bias, a pulse bias, and / or a direct current bias is applied to the developing sleeve 115 by the bias applying means 133.

  When the transfer paper P is conveyed in the transfer section, the toner image on the surface of the photosensitive drum is electrostatically transferred onto the transfer paper P by charging of the transfer charger 134 from the back surface (the side opposite to the photosensitive drum 110) of the transfer paper P. Transcribed. The transfer paper P separated from the photosensitive drum is transported by a transport belt 135, and a toner image on the transfer paper is fixed by a heat and pressure fixing device 136 to form a toner image.

  The developer remaining on the photosensitive drum after the transfer process is removed by a cleaner 138 having a cleaning blade 137. The cleaned photosensitive drum is neutralized by erase exposure 139, and the process starting from the charging process by the primary charger 131 is repeated again.

  Hereinafter, the present invention will be specifically described, but the technical scope of the present invention is not limited thereto.

All parts in the following formulations are parts by mass unless otherwise specified.
[Preparation of developer carrier]
[Binder resin]
A-1: Resol type phenol resin (ammonia catalyst used, containing 40% methanol, manufactured by Dainippon Ink & Chemicals, trade name: J325)
A-2: Resol type phenol resin (NaOH catalyst used, containing 40% methanol, manufactured by Dainippon Ink & Chemicals, trade name: Phenolite GF-9000)
A-3: Methyl methacrylate-dimethylaminoethyl methacrylate copolymer (resin obtained by mixing methyl methacrylate monomer and dimethylaminoethyl methacrylate monomer in a molar ratio of 90:10 and solution polymerization in toluene (Mw = 9,200, Mn = 4,500, Mw / Mn = 2.1, containing 40% toluene)
[Carbon black]
As the conductive carbon black, Conductex 975 (trade name) manufactured by Columbia Carbon Co., Ltd. was used.
[Graphitized particles]
B-1: β-resin was extracted from coal tar pitch by solvent fractionation, and this was subjected to hydrogenation and heavy treatment. Subsequently, the solvent-soluble component was removed with toluene to obtain a mesophase pitch. The obtained bulk mesophase pitch was finely pulverized, oxidized in air at about 800 ° C., calcined at 3000 ° C. in a nitrogen atmosphere, graphitized, and further classified to a volume average particle size of 2.9 μm. Graphitized particles B-1 were obtained. The graphitized particle B-1 had a graphitization degree p (002) of 0.32.

  B-2: Mesocarbon microbeads obtained by heat-treating coal-based heavy oil were washed and dried. Dispersion was mechanically performed with an atomizer mill, and primary heat treatment was performed at 1200 ° C. in a nitrogen atmosphere to carbonize. Next, secondary dispersion was performed with an atomizer mill, followed by heat treatment at 2800 ° C. in a nitrogen atmosphere, and further classified to collect graphitized particles having a volume average particle size of 3.5 μm to obtain graphitized particles B-2. . The graphitized particle B-2 had a graphitization degree p (002) of 0.47.

  B-3: Using a mixture of coke and tar pitch, this mixture was kneaded at a temperature equal to or higher than the softening point of tar pitch, extruded, and subjected to primary firing at 1000 ° C. in a nitrogen atmosphere for carbonization. Subsequently, impregnation with coal tar pitch was performed, followed by secondary firing at 2800 ° C. in a nitrogen atmosphere, followed by pulverization and classification to obtain graphitized particles B-3 having a volume average particle size of 6.4 μm. The graphitized particle B-3 had a graphitization degree p (002) of 0.11.

B-4: β-resin was extracted from coal tar pitch by solvent fractionation, and this was subjected to hydrogenation and heavy treatment. Subsequently, the solvent-soluble component was removed with toluene to obtain mesophase pitch. The bulk mesophase pitch was pulverized and oxidized at about 800 ° C. in air. Thereafter, it was calcined and graphitized at 1700 ° C. in a nitrogen atmosphere, and further classified to obtain graphitized particles B-4 having a volume average particle diameter of 3.2 μm. Graphitized particle B-4 had a degree of graphitization p (002) of 1.03.
[Unevenness-forming particles]
Nika beads PC0520 and Nika beads PC1020 (both trade names, manufactured by Nippon Carbon Co., Ltd.), which are conductive spherical particles, were used. Hereinafter, Nikabeads PC0520 is denoted as C-1, and Nikabeads PC1020 is denoted as C-2.
[Preparation of resin coating layer]
S-1: A resin coating layer was prepared on the substrate surface, and a developer carrying member (developing sleeve) was produced.

Binder resin A-1 333 parts Conductive carbon black 10 parts Graphitized particles B-1 90 parts 1 100 parts Unevenness-forming particles C-1 45 parts Methanol 200 parts Add glass beads with a diameter of 1 mm to the above materials as media particles, disperse in a sand mill for 2 hours, separate the beads using a sieve, and then remove the solids with methanol. The coating liquid was prepared by adjusting to 44%. Using this coating solution, a cylindrical aluminum tube with an outer diameter of 20 mm and a center line average roughness Ra = 0.2 μm is vertically set up, rotated at a constant speed, and masked at the upper and lower ends, and sprayed. The resin coating layer was formed by coating while lowering the gun at a constant speed. The coating was performed in an environment of 23 ° C./50% RH. Subsequently, the resin coating layer was cured by heating at 150 ° C. for 30 minutes in a hot air drying furnace, to produce a developer carrying member (developing sleeve) S-1. Table 2 lists the formulation and physical properties of the resin coating layer of the developer carrier (developing sleeve) S-1.

  S-2: A developer carrying member (developing sleeve) S-2 was prepared in the same manner as S-1, except that the coating liquid was prepared with the material configuration and mixing ratio shown in Table 2.

  S-3: A developer carrier (developing sleeve) S-3 in the same manner as in S-1 except that the material composition and blending ratio shown in Table 2 were used, and the solvent added during coating production was changed from methanol to ethanol. Was made.

  S-4: A developer carrier (developing sleeve) S as in S-1 except that the material composition and blending ratio shown in Table 2 were used, and the solid content of the coating liquid was reduced from 44% to 40%. -4 was produced.

  S-5: A developer carrying member (developing sleeve) S-5 was prepared in the same manner as S-1, except that the coating liquid was prepared with the material configuration and mixing ratio shown in Table 2.

  S-6: A developer carrying member (developing sleeve) S-6 was prepared in the same manner as S-1, except that the coating liquid was prepared with the material configuration and mixing ratio shown in Table 2.

  S-7: The material composition and blending ratio shown in Table 2 were changed, the solvent to be added was changed from methanol to ethyl acetate, and the coating liquid was prepared with a solid content of 35%. In the same manner, a developer carrying member (developing sleeve) S-7 was produced.

  S-8: A developer carrying member (developing sleeve) S-8 was produced in the same manner as S-1, except that the coating liquid was produced with the material constitution and mixing ratio shown in Table 2.

  S-9: A developer carrying member (developing sleeve) S-9 was produced in the same manner as S-1, except that the coating liquid was produced with the material configuration and mixing ratio shown in Table 2. The organic molybdate compound used is an organic molybdenum compound composed of sulfurized oxymolybdenum dithiocarbamate represented by the following structural formula.

Ｓ−１０：表２に示した材料構成及び配合比にて塗工液を作製した他は、Ｓ−１と同様にして現像剤担持体（現像スリーブ）Ｓ−１０を作製した。

S-10: A developer carrying member (developing sleeve) S-10 was prepared in the same manner as S-1, except that the coating liquid was prepared with the material configuration and mixing ratio shown in Table 2.

  S-11: A developer carrying member (developing sleeve) S-11 was produced in the same manner as S-1, except that the coating liquid was produced with the material configuration and mixing ratio shown in Table 2.

  S-12: A developer carrying member (developing sleeve) S-12 was produced in the same manner as S-1, except that the coating liquid was produced with the material configuration and mixing ratio shown in Table 2.

  S-13: A developer carrying member (similar to S-1) except that a compound having a sulfur atom and a nitrogen atom was not contained and a coating liquid was prepared with the material constitution and mixing ratio shown in Table 2. Developing sleeve) S-13 was produced.

  S-14: A developer carrying member (developing sleeve) S-14 was produced in the same manner as S-1 except that the addition amount of the compound having a sulfur atom and a nitrogen atom was changed.

  S-15: A developer carrying member (developing sleeve) S-15 was produced in the same manner as S-1, except that coating was performed in an environment of 45 ° C./20% RH.

  S-16: Developer carrying member (developing sleeve) S-16 as in S-1, except that the material composition and blending ratio shown in Table 2 were used, and the solvent added during coating production was changed from methanol to ethanol. Was made.

  S-17: A developer carrying member (developing sleeve) S-17 was produced in the same manner as S-1, except that the coating liquid was produced with the material constitution and mixing ratio shown in Table 2.

［現像剤の調製］
磁性体の製造例１
硫酸第一鉄水溶液中に、鉄イオンに対して１．０当量〜１．１当量の水酸化ナトリウム水溶液を混合し、水酸化第一鉄を含む水溶液を調製した。水溶液のｐＨを９前後に維持しながら空気を吹き込み、８０秒〜９０秒で酸化反応を行い、種晶を生成させるスラリー液を調製した。次いでこのスラリー液に、当初のアルカリ量（水酸化ナトリウムのナトリウム成分）に対し０．９当量〜１．２当量となるよう硫酸第一鉄水溶液を加えた後、スラリー液をｐＨ８に維持して、空気を吹き込みながら酸化反応を進行させ、生成した磁性体粒子を洗浄、濾過して一旦取り出した。この時、含水サンプルを少量採取し、含水量を測定した。次に、この含水サンプルを乾燥せずに別の水系媒体中に再分散させた後、再分散液のｐＨを約６に調整し、十分攪拌しながらシランカップリング剤（ｎ−Ｃ₉Ｈ₁₇Ｓｉ（ＯＣＨ₃）₃）を磁性酸化鉄１００部に対し２部（磁性体の量は含水サンプルから含水量を引いた値として計算した）添加し、カップリング処理を行った。生成した磁性体粒子を常法により洗浄、濾過、乾燥し、次いで若干凝集している粒子を解砕処理して疎水化磁性体１を得た。疎水化磁性体１は平均粒径が０．２０μｍ、疎水化度が８３であった。

[Developer preparation]
Production example 1 of magnetic material
An aqueous solution containing ferrous hydroxide was prepared by mixing 1.0 equivalent to 1.1 equivalent of an aqueous sodium hydroxide solution with respect to iron ions in the aqueous ferrous sulfate solution. Air was blown in while maintaining the pH of the aqueous solution at around 9, and an oxidation reaction was performed in 80 to 90 seconds to prepare a slurry liquid for generating seed crystals. Subsequently, after adding ferrous sulfate aqueous solution to this slurry liquid so that it may become 0.9 equivalent-1.2 equivalent with respect to the original amount of alkalis (sodium component of sodium hydroxide), the slurry liquid was maintained at pH8. Then, the oxidation reaction was advanced while blowing air, and the produced magnetic particles were washed, filtered and once taken out. At this time, a small amount of a water-containing sample was collected and the water content was measured. Next, this water-containing sample was re-dispersed in another aqueous medium without being dried, and then the pH of the re-dispersed liquid was adjusted to about 6, and the silane coupling agent (n-C ₉ H _{17 was} thoroughly stirred. 2 parts of Si (OCH ₃ ) ₃ ) was added to 100 parts of magnetic iron oxide (the amount of the magnetic material was calculated as a value obtained by subtracting the water content from the water-containing sample), and a coupling treatment was performed. The produced magnetic particles were washed, filtered and dried by a conventional method, and then the slightly agglomerated particles were crushed to obtain a hydrophobized magnetic material 1. Hydrophobized magnetic substance 1 had an average particle size of 0.20 μm and a degree of hydrophobicity of 83.

Production example 2 of magnetic material
In Production Example 1 of the magnetic material, n-C ₁₀ H ₂₁ Si (OCH ₃ ) ₃ is used as a silane coupling agent, 1 part per 100 parts of magnetic iron oxide (the amount of the magnetic material is obtained by subtracting the water content from the water-containing sample). The magnetic substance 2 was obtained in the same manner as in Production Example 1 of the magnetic substance except that it was added and subjected to a coupling treatment. The magnetic body 2 had an average particle size of 0.18 μm and a degree of hydrophobicity of 55.

Production example 3 of magnetic material
In Production Example 1 of the magnetic material, the amount of sodium hydroxide aqueous solution to be added and the reaction conditions were adjusted to allow the oxidation reaction to proceed, and the magnetic material produced after completion of the oxidation reaction was washed, filtered and dried to obtain a magnetic material. . Thereafter, 100 parts of the obtained magnetic material is dispersed in a toluene solution containing 5.0 parts of γ-metachloroxypropyltrimethoxysilane coupling agent, heat-treated at 100 ° C. for 3 hours, and dried to be hydrophobized magnetic material 3 Got. Hydrophobized magnetic substance 3 had an average particle size of 0.19 μm and a degree of hydrophobicity of 35.

After warming the 0.1M-Na ₃ PO ₄ aqueous solution 451 parts of the closing and 60 ° C. in Preparation of ion-exchanged water 709 parts of a magnetic developer T-1, addition of 1.0 M-CaCl ₂ aqueous solution 67.7 parts Thus, an aqueous medium containing Ca ₃ (PO ₄ ) ₂ was prepared.

  On the other hand, a uniformly dispersed monomer composition having the following composition was prepared using an attritor (Mitsui Miike Chemical Co., Ltd.). The monomer composition was heated to 60 ° C., and 7 parts of ester wax (maximum endothermic peak 72 ° C. in DSC) was added and dissolved therein. The polymerization initiator 2,2-azobis (2, 4-dimethylvaleronitrile) was dissolved.

Composition Styrene 78 parts N-butyl acrylate 22 parts Divinylbenzene 0.5 part Saturated polyester resin (acid value 8, peak molecular weight (Mp) 12000) 2 parts Negative charge control agent (Hodogaya Chemical Co., Ltd., trade name) : T-77) 1 part Magnetic body 1 88 parts The above aqueous medium is charged with 201.5 parts of the above-mentioned monomer composition / ester wax / polymerization initiator mixture at 60 ° C. under N ₂ atmosphere. The mixture was stirred and granulated at 10,000 rpm for 15 minutes with a TK homomixer (Special Machine Industries Co., Ltd.). Thereafter, the mixture was reacted at 70 ° C. for 5 hours while stirring with a paddle stirring blade. Thereafter, the liquid temperature was maintained at 80 ° C., and stirring was further continued for 4 hours. After completion of the reaction, distillation was further carried out at 80 ° C. for 2 hours, after which the suspension was cooled, hydrochloric acid was added to dissolve the dispersant, filtered, washed with water, and dried to give black particles having a weight average particle diameter of 7.5 μm. Got.

100 parts of the black particles, and 1.2 parts of hydrophobic silica fine powder having a BET value of 120 m ² / g after treatment with hexamethyldisilazane on silica having a primary particle size of 12 nm and treatment with silicone oil; Were mixed using a Henschel mixer (Mitsui Miike Chemical Co., Ltd.) to prepare a magnetic developer T-1. Table 3 shows the physical properties of the magnetic developer T-1.

Production Example of Magnetic Developer T-2 A magnetic developer T-2 was prepared in the same manner as in the production example of the magnetic developer T-1, except that the magnetic body 1 was changed to the magnetic body 2. Table 3 shows the physical properties of the magnetic developer T-2.

Production Example of Magnetic Developer T-3 A Henschel mixer (FM-75 type, manufactured by Mitsui Miike Chemical Co., Ltd.) was used, and a biaxial kneader (PCM) heated to 130 ° C. with a composition mixed with the following composition: -30 type, manufactured by Ikegai Iron Works Co., Ltd.), and the cooled kneaded product was coarsely pulverized with a hammer mill to obtain a coarsely pulverized product. The resulting coarsely pulverized product is finely pulverized with a PJM jet pulverizer (manufactured by Nippon Pneumatic Industry Co., Ltd.), Fine powder and coarse powder were classified and removed simultaneously to obtain toner particles. Hydrophobic silica was externally added to 100 parts of the obtained toner particles in the same manner as in Production Example of Magnetic Developer T-1 to prepare Magnetic Developer T-3 having a weight average particle size of 7.2 μm. . Table 3 shows the physical properties of the magnetic developer T-3.

Composition Styrene / n-butyl acrylate copolymer (monomer ratio: 78/22)
(Mn = 25000, Mw / Mn = 2.5) 100 parts Saturated polyester resin (acid value 8, peak molecular weight (Mp) 12000) 2 parts Negatively chargeable charge control agent (Hodogaya Chemical Industries, trade name: T -77) 1 part Surface-treated iron oxide particles-1 88 parts Ester wax used for magnetic developer T-1 7 parts Production example of magnetic developer T-4 In the production example of magnetic developer T-1, the magnetic substance A magnetic developer T-4 was prepared in the same manner as in the production example of the magnetic developer T-1, except that 1 was changed to the magnetic material 3. Table 3 shows the physical properties of the magnetic developer T-4.

［実施例１］
作製した現像剤担持体（現像スリーブ）Ｓ−１にマグネットローラーを装着してフランジを嵌合し、図５に示したような構成の現像装置を有するＨｅｗｌｅｔｔ−Ｐａｃｋａｒｄ社製Ｌａｓｅｒ Ｊｅｔ４３５０（商品名）に装着した。上記磁性現像剤Ｔ−１を用いて、常温常湿度環境（２３℃、５０％ＲＨ；Ｎ／Ｎ）、低温低湿度環境（１５℃、１０％ＲＨ；Ｌ／Ｌ）及び高温高湿度環境（３２℃、８５％ＲＨ；Ｈ／Ｈ）下でそれぞれ１枚／４秒の間欠モードで２．５万枚の通紙を行なった。

[Example 1]
Laser Jet 4350 (trade name) manufactured by Hewlett-Packard Co., which has a developing device having a configuration as shown in FIG. Attached to. Using the magnetic developer T-1, normal temperature and normal humidity environment (23 ° C., 50% RH; N / N), low temperature and low humidity environment (15 ° C., 10% RH; L / L) and high temperature and high humidity environment ( 25,000 sheets were passed in an intermittent mode of 1 sheet / 4 seconds each at 32 ° C. and 85% RH (H / H).

Image evaluation was performed by the following method. The printing during running was a horizontal line with a printing ratio of 1%, the initial evaluation was for the 10th sheet, and the durability evaluation was evaluated according to the following criteria after the end of the durability test. The results are shown in Table 4.
(1) Image Density The print image density of a 5 mm diameter round part on the test pattern with an image ratio of 5.5% is measured with a reflection densitometer RD918 (manufactured by Macbeth), and an average value of 10 points is taken. The image density was used.
(2) Fog Measure the reflectance of the solid white image in the appropriate image, and further measure the reflectance of the unused transfer paper. (Worst value of the reflectance of the solid white image-Average reflectance of the unused transfer paper) Value) was defined as fog density and evaluated according to the following criteria. The reflectance was measured at 10 points at random using TC-6DS (manufactured by Tokyo Denshoku).

A: 1.0% or less (fogging is not visually recognized)
B: 1.0% to 2.0% (Fog is not recognized unless watched)
C: 2.0% to 3.0% (although there is fog, there is no practical problem)
D: 3.0% or more (fogging is conspicuous NG level)
(3) Image quality The initial and final output images of durability evaluation were observed with a magnifying glass or visually, and evaluated according to the following criteria.

A: A clear image that does not scatter even when viewed with a magnifying glass at a magnification of 10 times. B: A clear image as long as it is visually observed. C: A slight scatter is observed, but there is no practical problem. Stands out. NG level (4) sleeve ghost After drawing a strip-shaped solid black portion (Fig. 6 (a)) of width x length l, halftone (Fig. 6 (b)) of width y (however, y> x) length l ). As shown in FIG. 6C, the image density of this halftone image is determined as a region (a portion after the length z of the rotation of the developing sleeve from the image formation start point) and a region a (the image formation start point to the development sleeve). In a portion that overlaps a portion where a solid black image is drawn up to the length z of one rotation) and a region c (a portion where only halftone is drawn from the image formation start point to the length z of one rotation of the developing sleeve) Each image density was measured, and the density difference (degree of shading) was evaluated based on the following criteria as the presence or absence of sleeve ghost.

A: No difference in density is observed (density difference is less than 0.02)
B: A slight density difference is observed between the area A and the area C (the density difference is 0.02 or more and less than 0.04).
C: A slight density difference is observed in each of the areas A, A and C (the density difference is 0.04 or more and less than 007).
D: A remarkable density difference is observed (the density difference is 0.07 or more). NG level (5) Toner charge amount (Q / M) and toner carry amount (M / S) on developer carrier
The toner carried on the developer carrying member is sucked and collected by a metal cylindrical tube and a cylindrical filter. At that time, the charge amount Q stored in the condenser, the collected toner mass M and the toner are sucked through the metal cylindrical tube. The measured area S was measured. From these values, the charge amount Q / M (mC / kg) per unit mass and the toner mass M / S (dg / m ² ) per unit area were calculated.
[Examples 2 to 15, Comparative Examples 1 to 8]
Image evaluation was performed by the same image evaluation method as in Example 1 using developer carriers S-1 to S-17 and magnetic developers T-1 to T-4. The results are shown in Table 4.

It is a figure which shows typically the cross section of the resin coating layer on the developer carrier surface of an example used for the electrophotographic image development method of this invention. It is a figure which shows typically the cross section of the resin coating layer on the developer carrier surface of another example used for the electrophotographic image development method of this invention. It is a figure which shows typically the cross section of the resin coating layer on the developer carrier surface of another example used for the electrophotographic image development method of this invention. 1 is a schematic configuration diagram showing an example of a developing device to which an electrophotographic developing method of the present invention is applied. It is a schematic block diagram which shows another example of the image development apparatus to which the electrophotographic developing method of this invention is applied. It is explanatory drawing about the evaluation method of the sleeve ghost by the electrophotographic developing method of this invention. It is a schematic block diagram which shows an example of the process cartridge of this invention. It is a schematic block diagram which shows an example of the electrophotographic apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Resin coating layer a Binder resin b Conductive agent c Solid particle d Concavity and convexity formation particle 2,606 Base | substrate 51,601 Photoconductor (electrostatic latent image carrier)
58, 610 Developer carrier 67, 602, 616 Developer layer thickness regulating member (developing blade)
T developer 53, 603 developer container D developing region 604 partition member 605 stirring transport member 607 resin coating layer 608 developing sleeve 609 magnet (magnet roller)
611 Agitating and conveying member 612 Developer supply member 613 Developing bias power source 614 First chamber 615 Second chamber

Claims (15)

When the developer carrying member carrying the developer contained in the developing container is rotated, the developer formed in a layer having a constant thickness by the developer layer thickness regulating member that contacts the developer carrying member, In an electrophotographic development method in which development is performed by transferring to an electrostatic latent image formed on an electrostatic latent image carrier, and transporting it to a development area facing the electrostatic latent image carrier, a resin coating layer is provided on the surface of the substrate. The resin coating layer contains a compound having a sulfur atom and a nitrogen atom, and the content of sulfur atoms by X-ray photoelectron spectroscopy analysis on the surface of the resin coating layer is S (1) (atomic%), the content of nitrogen atom When the rate is N (atomic%) and Y = S (1) / N, formula (1) and formula (2)
0.050 ≦ S (1) ≦ 1.500 (1)
0.100 ≦ Y ≦ 1.500 (2)
A developer carrier that satisfies
Toner particles containing a magnetic material including a binder resin and magnetic iron oxide, and the toner particles have a carbon atom content A (atomic%) and an iron atom content B (atomic atoms) by X-ray photoelectron spectroscopy on the surface. %), The ratio B / A of the content ratio of iron atoms to the content ratio A of carbon atoms is less than 0.001, and iron and iron compounds released from toner particles have a release ratio X (% ), The formula (4) and the formula (5)
X ≦ 3.00 (4)
−0.05X + 0.2 ≦ Y ≦ −0.3X + 1.5 (5)
An electrophotographic developing method comprising using a developer satisfying the above requirements. When the resin coating layer of the developer carrying member has C (atomic%) as the carbon atom content by surface X-ray photoelectron spectroscopy analysis, the formula (3)
0.005 ≦ N / C ≦ 0.070 (3)
The electrophotographic development method according to claim 1, wherein: When the resin coating layer of the developer carrier has S (2) (atomic%) and Z = S (2) / S (1), the content of sulfur atoms by internal X-ray photoelectron spectroscopy is 6)
0.300 ≦ Z ≦ 0.900 (6)
The electrophotographic developing method according to claim 1, wherein:   The compound having a sulfur atom and a nitrogen atom contained in the resin coating layer contains a quaternary ammonium salt that is positively charged with respect to the iron powder. An electrophotographic developing method.   5. The electrophotographic development method according to claim 1, wherein the compound having a sulfur atom and a nitrogen atom contained in the resin coating layer contains a sulfonic acid group. Resin coating layer, -NH _2, = NH, and according to any one of claims 1 to 5, characterized in that it comprises a binder resin having one or more selected from the group consisting of -NH- An electrophotographic developing method.   The electrophotographic development method according to claim 1, wherein the resin coating layer contains graphitized particles.   8. The electrophotographic developing method according to claim 7, wherein the graphitized particles have a graphitization degree p (002) of 0.20 or more and 0.95 or less.   The electrophotographic development method according to claim 7 or 8, wherein the graphitized particles contain graphitized particles obtained by graphitizing bulk mesophase pitch particles.   9. The electrophotographic developing method according to claim 7, wherein the graphitized particles contain graphitized particles obtained by graphitizing mesocarbon microbead particles.   The electrophotographic development method according to claim 1, wherein the resin coating layer contains particles that form irregularities on the surface.   12. The toner particles contained in the developer have an average circularity of 0.970 or more in particles having an equivalent circle diameter of 3 μm or more and 400 μm or less measured by a flow type particle image measuring device. The electrophotographic developing method according to any one of the above.   A developer carrier used in the electrophotographic development method according to claim 1.   13. A process cartridge using the electrophotographic developing method according to claim 1.   An electrophotographic apparatus using the electrophotographic developing method according to claim 1.

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