JP2007011045A - Carrier, developer, image forming method, and process cartridge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a carrier which hardly causes carrier deposition in the early stages and with time and allows formation of good images having high image density and good graininess, a developer, an image forming method and a process cartridge. <P>SOLUTION: The carrier has a covering layer containing a silicone resin and a rate of elastic deformation of the resin component constituting the covering layer is 30-90%. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a carrier, a developer, an image forming method, and a process cartridge.

  The electrophotographic development system uses a so-called one-component development system consisting mainly of toner, a mixture of glass beads, a magnetic carrier or a coated carrier whose surface is coated with a resin and toner. There are two-component development systems.

  The two-component development method is suitable for high-speed printing and is easy to handle non-magnetic toner, and thus is widely used in full-color printing apparatuses. However, the full-color printing apparatus needs to include a plurality of developing devices in the apparatus, and has disadvantages such as an increase in the size and weight of the apparatus as compared with a monochrome machine. In particular, the two-component developing device needs to have a developer storage volume and a stirring mechanism separately from the toner as compared with the one-component developing device. A small amount of is essential.

  The carrier in the developer is repeatedly subjected to mechanical friction and impact in the developing device by friction with toner, a sliding friction member such as a sleeve and a blade, a regulating member, and a stirring and conveying member such as a screw and paddle. For this reason, when the amount of the developer is reduced, the friction between the toner and the carrier generated per print increases, the frequency of the carrier passing through the developing portion increases, and the carrier contamination (spent) in the developing unit rapidly increases. To progress to.

  In order to prevent such a carrier spent, the carrier core material surface is coated with a resin having a low surface energy, specifically, a fluororesin, a silicone resin or the like, thereby extending the life of the carrier. .

  For example, a carrier in which the surface of the core particle is coated with two or more layers of silicone resin so that there is no adhesion between the layers (see Patent Document 1), and a carrier in which the core particle surface is sequentially coated with an elastic body and a silicone polymer ( There is known a carrier (see Patent Document 3) in which the surface of a magnetic core material is coated with a film containing a silicone resin, an aminosilane coupling agent and a fluorine-containing silane coupling agent.

  However, in recent years, the toner tends to have a smaller particle size in order to improve the image quality, and carrier spent tends to occur. Furthermore, in the case of a developer in which maintenance is facilitated by adding wax to the toner, the amount of carrier contamination (spent) increases, resulting in a decrease in toner charge amount, toner scattering, and background contamination.

In addition, combined with higher printing speed, carrier durability, especially high wear resistance of the coating layer of the carrier, and quick charging over a long period of time while preventing carrier spent by toner and other members. Maintaining has become more important than ever.
JP-A-57-96355 JP 57-78552 A JP 2003-280289 A

  The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to provide a carrier capable of forming an image with low initial and time-dependent carrier adhesion, high image density, and good graininess. And It is another object of the present invention to provide a developer, an image forming method, and a process cartridge using the carrier.

  The invention according to claim 1 is a carrier having magnetic core material particles and a coating layer formed on the surface of the core material particles, wherein the coating layer contains a silicone resin, and the coating layer is The elastic deformation rate of the constituent resin component is 30% or more and 90% or less. Thereby, it is possible to provide a carrier capable of forming an image with little occurrence of carrier adhesion at the initial stage and with time, high image density, and good graininess.

The invention according to claim 2 is the carrier according to claim 1, wherein the resin component has a universal hardness of 200 N / mm ² or more and 3000 N / mm ² or less. Thereby, the abrasion resistance and impact resistance of the coating layer can be improved.

  According to a third aspect of the present invention, in the carrier according to the first or second aspect, the weight average particle size is 22 μm or more and 32 μm or less, and the ratio of the weight average particle size to the number average particle size is 1.0 or more and 1. 2 or less, the content of particles having a particle size of less than 20 μm is 0 to 7% by weight, and the content of particles having a particle size of less than 36 μm is 90 to 100% by weight. Features. Thereby, it is possible to suppress the occurrence of carrier adhesion and to form an image with good graininess.

  According to a fourth aspect of the present invention, in the carrier according to any one of the first to third aspects, the coating layer further contains an aminosilane coupling agent. Thereby, durability can be improved.

  The invention according to claim 5 is the carrier according to any one of claims 1 to 4, wherein the core particles have a magnetization in a magnetic field of 1 kOe of 70 emu / g or more and 150 emu / g or less. And Thereby, generation | occurrence | production of carrier adhesion can be suppressed.

The invention according to claim 6 is the carrier according to any one of claims 1 to 5, wherein the core particles have a bulk density of 2.35 g / cm ³ or more and 2.50 g / cm ³ or less. It is characterized by that. Thereby, generation | occurrence | production of carrier adhesion can be suppressed.

According to a seventh aspect of the present invention, in the carrier according to any one of the first to sixth aspects, the electrical resistivity in an electric field of 50 V / mm is 1 × 10 ¹⁴ Ω · cm or more and 1 × 10 ¹⁷ Ω · cm. The electrical resistivity in an electric field of 250 V / mm is 1 × 10 ⁸ Ω · cm or more and 1 × 10 ¹⁶ Ω · cm or less. Thereby, the fluctuation | variation by charging environment and the fall of the charge amount at the time of leaving a developing agent can be suppressed.

  According to an eighth aspect of the present invention, in the carrier according to any one of the first to seventh aspects, the coating layer contains hard particles. Thereby, the intensity | strength of a coating layer can be improved.

  According to a ninth aspect of the present invention, in the carrier according to the eighth aspect, the hard particles contain at least one of an oxide of silicon, an oxide of titanium, and an oxide of aluminum. Thereby, the intensity | strength of a coating layer can be improved.

  A tenth aspect of the invention is characterized in that the developer comprises the carrier and the toner according to any one of the first to ninth aspects. Accordingly, it is possible to provide a developer capable of forming an image with little occurrence of carrier adhesion at the initial time and time, high image density, and good graininess.

  According to an eleventh aspect of the present invention, in the image forming method, at least the electrostatic latent image formed on the surface of the photoconductor is developed using the developer according to the tenth aspect. . Thereby, it is possible to provide an image forming method capable of forming an image with little occurrence of carrier adhesion at the initial stage and with time, high image density, and good graininess.

  According to a twelfth aspect of the present invention, in the process cartridge, at least the photosensitive member and a developing unit that develops the electrostatic latent image formed on the surface of the photosensitive member using the developer according to the tenth aspect are integrated. It is characterized by supporting. As a result, it is possible to provide a process cartridge capable of forming an image with little occurrence of carrier adhesion at the initial stage and with time, high image density, and good graininess.

  According to the present invention, it is possible to provide a carrier capable of forming an image with little occurrence of carrier adhesion at the initial stage and with time, high image density, and good graininess. Furthermore, a developer, an image forming method, and a process cartridge using the carrier can be provided.

  Next, the best mode for carrying out the present invention will be described with reference to the drawings.

  In addition, the following description is an example of the best form in this invention, Comprising: This invention is not limited at all by this.

The carrier of the present invention is a carrier having magnetic core material particles and a coating layer formed on the surface of the core material particles, and the coating layer contains a silicone resin. Further, the resin component constituting the coating layer has an elastic deformation rate η _HU in the universal hardness test of 30 to 90%, preferably 35 to 90%. When η _HU is less than 30%, when carriers collide with each other in the developer, a problem that the resin is cracked and peeled off by impact is likely to occur, and the charging behavior of the carrier changes. In addition, a material that exhibits a rubber-like behavior such that η _HU exceeds 90% is a coating layer due to an increase in mechanical frictional force received from a rubbing member such as a sleeve or a blade, or a stirring and conveying member such as a screw or paddle. As a result, the carrier wears easily and the charge behavior of the carrier changes.

Further, the resin component constituting the coating layer is preferably universal hardness HU is 200~3000N / mm ^2, more preferably 250~3000N / mm ^2. If the HU is less than 200 N / mm ² , the coating layer tends to wear out due to mechanical friction caused by a rubbing member, a stirring and conveying member, and the charging behavior of the carrier may change. On the other hand, if HU exceeds 3000 N / mm ² , when carriers collide with each other in the developer, a problem that the resin is cracked and peeled off by impact is likely to occur, and the carrier charging behavior may change.

In the present invention, η _HU and HU can be measured with a Fischer scope H100C using a Vickers indenter under a maximum load of 9.8 mN.

η _HU is the formula

から求めることができる。ここで、Ｗ_{ｅｌａｓｔｉｃ}は、弾性変形エネルギーであり、Ｗ_{ｔｏｔａｌ}は、全変形エネルギーであり、Ｆ１（ｈ）は、除荷時の変形曲線であり、Ｆ２（ｈ）は、加負荷時の変形曲線であり、ｈｍａｘは、最大負荷時下でのくぼみ深さであり、ｈｍｉｎは、除荷終了時の残留くぼみ深さである。

Can be obtained from Here, W _elastic is elastic deformation energy, W _total is total deformation energy, F1 (h) is a deformation curve at unloading, and F2 (h) is a deformation curve at the time of loading. Hmax is the depth of the dent under the maximum load, and hmin is the depth of the dent at the end of unloading.

HU is expressed by the formula HU = F / 26.43h ²
Can be obtained from Here, F is the test load (N), and h is the indentation depth (mm) under the test load.

Further, η _HU and HU can be measured by forming a film made of a resin component constituting the coating layer on the slide glass so as to be uniform with a measurable thickness.

  The carrier of the present invention preferably has a weight average particle diameter Dw of 22 to 32 μm, more preferably 23 to 30 μm. When Dw is larger than 32 μm, it becomes difficult for the toner to be faithfully developed with respect to the latent image, the variation in the dot diameter increases, and the graininess may decrease. In addition, when the toner concentration is increased, scumming may easily occur. When Dw is smaller than 22 μm, carrier adhesion tends to occur. The carrier adhesion indicates a phenomenon in which the carrier adheres to the image portion or the background portion of the electrostatic latent image. The stronger the electric field in the image area or the background area, the easier the carrier adheres. In addition, since an electric field is weakened by developing in an image part, compared with a background part, carrier adhesion does not generate | occur | produce easily. Carrier adhesion is not preferable because it may cause scratches on the photosensitive drum and the fixing roller.

  In the carrier of the present invention, the content of particles having a particle diameter of less than 20 μm is preferably 0 to 7% by weight, and more preferably 0 to 5% by weight. When the content of particles having a particle size of less than 20 μm is more than 7% by weight, the particle size distribution is widened and particles having a small magnetization are present in the magnetic brush, so that carrier adhesion is likely to occur. The content of particles having a particle size smaller than 20 μm is preferably 0.5% by weight or more. Thereby, the increase in the manufacturing cost of a carrier can be suppressed.

  Furthermore, in the carrier of the present invention, the content of particles having a particle size of less than 36 μm is preferably 90 to 100% by weight, more preferably 92 to 100% by weight. Further, when the number average particle diameter is Dp, Dw / Dp is preferably 1.0 to 1.2. Since the surface of the carrier having such a sharp particle size distribution is coated with the coating layer, a carrier with suppressed magnetization spread can be obtained, and the occurrence of carrier adhesion can be suppressed.

  In the present invention, Dp and Dw are calculated based on the particle size distribution (relationship between the number frequency and the particle size) of the particles measured on the basis of the number, and are expressed by the following equations.

Dp = {1 / Σ (n)} × {Σ (nD)}
Dw = {1 / Σ (nD ³ )} × {Σ (nD ⁴ )}
Here, D represents the representative particle size (μm) of particles present in each channel, and n is the number of particles present in each channel. The channel has a length for equally dividing the particle size range in the particle size distribution diagram, and in the present invention, 2 μm can be adopted. Moreover, the lower limit of the particle diameter of each channel can be adopted as the representative particle diameter of the particles present in each channel. As a particle size analyzer for measuring the particle size distribution, Microtrac particle size analyzer model HRA9320-X100 (manufactured by Honeywell) can be used.

  In the present invention, crushed particles of a magnetic material can be used as the core material particles. In the case of core particles such as ferrite and magnetite, the primary granulated product before firing is classified, and the fired particles are classified into particle powders having different particle size distribution by classification treatment, and then a plurality of particles. It can be obtained by mixing powder.

  As a method of classifying the core particles, known classification methods such as a sieving machine, a gravity classifier, a centrifugal classifier, an inertia classifier, etc. can be used, but productivity is good and the classification point can be easily changed. It is preferable to use an air classifier such as a gravity classifier, a centrifugal classifier, or an inertia classifier.

  In the present invention, the magnetization of the core particles when a magnetic field of 1 kOe is applied is preferably 50 to 150 emu / g, more preferably 70 to 150 emu / g. Thereby, generation | occurrence | production of carrier adhesion can be suppressed. If the magnetization of the core particles is less than 50 emu / g, carrier adhesion may easily occur.

  The magnetization of the core particles can be measured as follows using a BH tracer BHU-60 (manufactured by Riken Denshi Co., Ltd.). Fill the cylindrical cell with 1g of core particles, set it in the device, gradually increase the magnetic field to 3kOe, then gradually decrease it to 0 and then gradually increase the opposite magnetic field. 3 kOe. Further, after gradually reducing the magnetic field to zero, the magnetic field is applied in the same direction as the first. In this way, a BH curve is created, and 1 kOe magnetization is calculated from the figure.

  In the present invention, the core particles having a magnetization of 50 to 150 emu / g when a magnetic field of 1 kOe is applied include, for example, ferromagnetic materials such as iron and cobalt, magnetite, hematite, Li-based ferrite, and Mn—Zn-based materials. Examples thereof include ferrite, Cu—Zn ferrite, Ni—Zn ferrite, Ba ferrite, and Mn ferrite.

Ferrite is generally represented by the general formula (MO) x (NO) y (Fe ₂ O ₃ ) z
It is a sintered compact shown by. Here, x, y, and z represent the composition of ferrite, and as M and N, Ni, Cu, Zn, Mg, Mn, Sr, Ca, etc. can be mentioned independently, respectively, and metal oxide and iron oxide ( III) and a complete mixture.

  In the present invention, examples of the core particles having a magnetization of 70 to 150 emu / g when a 1 kOe magnetic field is applied include iron, magnetite, Mn—Mg—Sr ferrite, and Mn ferrite.

In the present invention, the bulk density of the core particles is preferably 2.35 g / cm ³ or more and 2.50 g / cm ³ or less. Thereby, generation | occurrence | production of carrier adhesion can be suppressed. When the bulk density is less than 2.35 g / cm ³ , even if the magnetization (emu / g) is large, the magnetic moment per particle is small, so that carrier adhesion is likely to occur.

  Factors that reduce the bulk density of the core particles include a porous structure and a surface uneven structure. In addition, if the irregularities on the surface of the core particles are large, the distribution of the film thickness of the coating layer may increase, and the charge amount and electrical resistivity are likely to be non-uniform, resulting in durability, carrier adhesion over time, etc. May have an effect.

Examples of a method for increasing the bulk density of the core particles include increasing the firing temperature. However, the core particles tend to be fused with each other and are difficult to disintegrate, and therefore, 2.50 g / cm ³ or less. It is preferable that

The bulk density of the core particles can be measured as follows according to the metal powder-apparent density test method (JIS-Z-2504). The core particles are naturally allowed to flow out from an orifice having a diameter of 2.5 mm, and the core particles are poured into a 25 cm ³ stainless steel cylindrical container directly below it, and then the container is filled with a nonmagnetic horizontal spatula. Scrape flat along the top edge of the plate in one operation. When the core material particles are difficult to flow out of the orifice having a diameter of 2.5 mm, the core material particles are naturally discharged from the orifice having a diameter of 5 mm. By this operation, the weight of the core particles per cm ³ can be obtained by dividing the weight of the core particles flowing into the container by the volume of the container 25 cm ³ . This is defined as the bulk density of the core particles.

  In the present invention, when the electric resistivity (Ω · cm) of the carrier is R, LogR at an applied electric field of 50 V / mm is preferably 14 or more and 17 or less. LogR at an applied electric field of 250 V / mm is preferably 8 or more and 16 or less. When the electrical resistivity is in the above range, it is possible to suppress fluctuation due to charging environment and a decrease in the charge amount when the developer is left. If LogR at an applied electric field of 50 V / mm is smaller than 14, the charge amount during standing may be greatly reduced. In addition, the variation in charge amount due to temperature and humidity may increase. If LogR at an applied electric field of 250 V / mm is greater than 16, image density may be reduced due to carrier charge-up during continuous printing.

  In the present invention, the electrical resistivity (Ω · cm) of the carrier at an applied electric field of 50 V / mm (or 250 V / mm) can be obtained as follows using the resistance measurement cell of FIG. A carrier 103 is filled in a cell 101 made of fluororesin in which an electrode 102a and an electrode 102b having a surface area of 2 cm × 4 cm are accommodated so that the distance between the electrodes is 2 mm, and a DC voltage of 100 V (or 500 V) is applied between both electrodes, DC resistance is measured using a high resistance meter 4329A (4329A + LJK 5HLVLVWDQFH OHWHU; manufactured by Yokogawa Hewlett-Packard Company), and an electrical resistivity (Ω · cm) is calculated.

  The filling method in measuring the resistance of the carrier is shown below. After the carrier has overflowed into the cell, the cell is tapped 20 times and scraped flat with a single operation along the top edge of the cell using a non-magnetic horizontal spatula.

The electrical resistivity of the carrier can be adjusted by controlling the electrical resistivity of the resin component constituting the coating layer and the film thickness of the coating layer. Moreover, you may adjust the electrical resistivity of a carrier by adding electroconductive particle to a coating layer. As the conductive particles, ZnO, metals or metal oxides such as Al, _SnO 2 doped with various SnO ₂ or various elements prepared by the _method, TiB _2, ZnB _2, borides such as MoB _2, carbonized Particles made of conductive polymers such as silicon, polyacetylene, poly (p-phenylene), poly (p-phenylene sulfide), polypyrrole, and polyethylene, carbon black such as furnace black, acetylene black, and channel black can be used. .

  These conductive particles are added to the solvent used for the coating solution of the coating layer or the coating solution of the coating layer, and then a dispersing machine using a medium such as a ball mill or a bead mill, or a stirrer equipped with high-speed rotating blades is used. Can be uniformly dispersed.

  In the present invention, the silicone resin used when forming the coating layer has the general formula

で示される繰り返し単位の少なくとも一つを含有することが好ましい。ここで、Ｒ^１は水素原子、ハロゲン基、ヒドロキシル基、メトキシ基、炭素数１〜４の低級アルキル基又はアリール基（フェニル基、トリル基等）であり、Ｒ^２は、炭素数１〜４のアルキレン基又はアリーレン基（フェニレン基等）である。

It preferably contains at least one repeating unit represented by Here, R ¹ is a hydrogen atom, a halogen group, a hydroxyl group, a methoxy group, a lower alkyl group having 1 to 4 carbon atoms or an aryl group (phenyl group, tolyl group, etc.), and R ² is 1 to 4 carbon atoms. An alkylene group or an arylene group (such as a phenylene group).

  The aryl group preferably has 6 to 20 carbon atoms, and more preferably 6 to 14 carbon atoms. As the aryl group, in addition to an aryl group derived from benzene (phenyl group), an aryl group derived from condensed polycyclic aromatic hydrocarbons such as naphthalene, phenanthrene and anthracene, and chain polycyclic aromatics such as biphenyl and terphenyl An aryl group derived from a hydrocarbon is included. The aryl group may be substituted with various substituents.

  The carbon number of the arylene group is preferably 6-20, and more preferably 6-14. Arylene groups include benzene-derived arylene groups (phenylene groups), arylene groups derived from condensed polycyclic aromatic hydrocarbons such as naphthalene, phenanthrene, and anthracene, and chain polycyclic aromatics such as biphenyl and terphenyl. A hydrocarbon-derived arylene group and the like are included. The arylene group may be substituted with various substituents.

  In the present invention, a straight silicone resin can be used when forming the coating layer. Examples of the straight silicone resin include KR271, KR272, KR282, KR252, KR255, KR152 (manufactured by Shin-Etsu Chemical Co., Ltd.), SR2400, SR2406 (manufactured by Toray Dow Corning Silicone).

  In forming the coating layer, modified silicone resins such as epoxy-modified silicone resins, acrylic-modified silicone resins, phenol-modified silicone resins, urethane-modified silicone resins, polyester-modified silicone resins, and alkyd-modified silicone resins may be used. Examples of the epoxy-modified silicone resin include ES-1001N (manufactured by Shin-Etsu Chemical Co., Ltd.) and SR2115 (manufactured by Toray Dow Corning Silicone Co., Ltd.). ) And the like, and examples of the polyester-modified silicone resin include KR-5203 (manufactured by Shin-Etsu Chemical Co., Ltd.). Examples of the alkyd-modified silicone resin include KR-206 (manufactured by Shin-Etsu Chemical Co., Ltd.) and SR2110 (Toray Dow). Corning Silicone Co., Ltd.) and the like, and examples of the urethane-modified silicone resin include KR-305 (manufactured by Shin-Etsu Chemical Co., Ltd.).

  In the present invention, the resin component constituting the coating layer includes, in addition to the silicone resin, polystyrene, polychlorostyrene, poly (α-methylstyrene), styrene-chlorostyrene copolymer, styrene-propylene copolymer, styrene- Butadiene copolymer, styrene-vinyl chloride copolymer, styrene-vinyl acetate copolymer, styrene-maleic acid copolymer, styrene-acrylic acid ester copolymer (styrene-methyl acrylate copolymer, styrene-acrylic) Ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-phenyl acrylate copolymer, etc.), styrene-methacrylic acid ester copolymer (styrene-methyl methacrylate copolymer) Polymer, styrene-ethyl methacrylate copolymer, styrene-medium Styrenic resins such as butyl crylate copolymer, styrene-phenyl methacrylate copolymer), styrene-α-methyl chloroacrylate copolymer, styrene-acrylonitrile-acrylate copolymer, epoxy resin, polyester Contains resin, polyethylene, polypropylene, ionomer resin, polyurethane resin, ketone resin, acrylic resin, ethylene-ethyl acrylate copolymer, xylene resin, polyamide resin, phenol resin, polycarbonate resin, melamine resin, fluorine-based resin, etc. Also good.

  As a method for forming the coating layer on the surface of the core particle, a known method such as a spray drying method, a dipping method, or a powder coating method can be used. In particular, the method using a fluidized bed type coating apparatus is effective for forming a uniform coating layer.

  The film thickness of the coating layer on the surface of the core particles is usually 0.02-1 μm, preferably 0.03-0.8 μm. Since the film thickness of the coating layer is extremely small compared with the particle diameter of the core particle, the particle diameter of the carrier having the coating layer formed on the surface and the particle of the core material is substantially the same.

  In the present invention, the coating layer preferably contains an aminosilane coupling agent. Thereby, a carrier with good durability can be obtained. Examples of the aminosilane coupling agent include the following.

被覆層の重量に対する被覆層に含まれるアミノシランカップリング剤の重量の比は、０．００１〜３０％であることが好ましい。なお、本願明細書及び特許請求の範囲において、アミノシランカップリング剤は、被覆層を構成する樹脂成分に含まれる。

The ratio of the weight of the aminosilane coupling agent contained in the coating layer to the weight of the coating layer is preferably 0.001 to 30%. In addition, in this-application specification and a claim, an aminosilane coupling agent is contained in the resin component which comprises a coating layer.

  Moreover, in order to reinforce a coating layer, it is preferable that a coating layer contains a hard particle. Among these, particles made of a metal oxide are preferably used because they have high uniformity in particle diameter, high affinity with the components of the coating layer, and a large reinforcing effect on the coating layer.

  As the hard particles, it is preferable to use particles obtained by mixing known materials such as Si oxide, Ti oxide, and Al oxide alone or in combination of two or more.

  The content of hard particles in the coating layer is preferably 2 to 70% by weight, more preferably 5 to 40% by weight. The content of the hard particles may be appropriately selected depending on the particle diameter and specific surface area. However, if the content is less than 2% by weight, the effect of improving the wear resistance of the coating layer is hardly exhibited. Particle detachment tends to occur.

  The developer of the present invention comprises the carrier of the present invention and a toner.

  As the toner, various known toners containing a binder resin mainly composed of a thermoplastic resin, a colorant, fine particles, a charge control agent, a release agent and the like can be used. The toner can be manufactured using a manufacturing method such as a polymerization method or a granulation method, and an amorphous or spherical toner is obtained. Either magnetic toner or non-magnetic toner can be used.

  As binder resin, styrene such as polystyrene and polyvinyltoluene, and homopolymers thereof, styrene-p-chlorostyrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-acrylic acid Methyl copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, Styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer , Styrene-maleic acid copolymerization , Styrene-maleic acid ester copolymer, polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester resin, polyurethane, epoxy resin, polyvinyl butyral, polyacrylic acid resin, rosin, Examples thereof include modified rosin, terpene resin, phenol resin, aliphatic or aliphatic hydrocarbon resin, aromatic petroleum resin, chlorinated paraffin, and paraffin wax. In addition, these can be used individually or in mixture of 2 or more types.

  The polyester resin can lower the melt viscosity while ensuring the stability during storage of the toner, as compared with the styrene resin or the acrylic resin. The polyester resin can be obtained, for example, by a polycondensation reaction between an alcohol component and a carboxylic acid component.

  Examples of the alcohol component include polyethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-propylene glycol, neopentyl glycol, and diols such as 1,4-butenediol, Etherified bisphenols such as 1,4-bis (hydroxymethyl) cyclohexane, bisphenol A, hydrogenated bisphenol A, polyoxyethylenated bisphenol A, polyoxypropylenated bisphenol A, etc., which are saturated or unsaturated with 3 to 22 carbon atoms. Divalent alcohol units substituted with saturated hydrocarbon groups, other divalent alcohol units, sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaesitol, dipentaes Tall, tripentaerythritol, sucrose, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, Trivalent or higher alcohol monomers such as trimethylolethane, trimethylolpropane, 1,3,5-trihydroxymethylbenzene and the like can be mentioned.

  Carboxylic acid components include monocarboxylic acids such as palmitic acid, stearic acid, oleic acid, maleic acid, fumaric acid, mesaconic acid, citraconic acid, terephthalic acid, cyclohexanedicarboxylic acid, succinic acid, adipic acid, sebacic acid, malonic acid , Divalent organic acid monomers in which they are substituted with a saturated or unsaturated hydrocarbon group having 3 to 22 carbon atoms, anhydrides of these acids, lower alkyl esters, and dimer acids from linolenic acid, 1,2,4-benzenetricarboxylic acid, 1,2,5-benzenetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 3,3-dicarboxymethylbutanoic acid, tetracarboxymethylmethane, 1,2,7,8 Octane tetracarboxylic acid Enboru trimer acid, a trivalent or higher polycarboxylic acid monomers anhydrides of these acids and the like.

  As the epoxy resin, a polycondensate of bisphenol A and epichlorohydrin can be used, and specifically, Epomic R362, R364, R365, R366, R367, R369 (Mitsui Petrochemical Industries, Ltd.) , Epototo YD-011, YD-012, YD-014, YD-904, YD-017 (above, manufactured by Tohto Kasei Co., Ltd.), Epocoat 1002, 1004, 1007 (above, manufactured by Shell Chemical Co., Ltd.) Can be mentioned.

  Colorants include carbon black, lamp black, iron black, ultramarine, nigrosine dye, aniline blue, phthalocyanine blue, Hansa Yellow G, rhodamine 6G lake, calco oil blue, chrome yellow, quinacridone, benzidine yellow, rose bengal, triallyl. Known dyes and pigments such as methane dyes, monoazo dyes and pigments, disazo dyes and pigments can be used singly or as a mixture of two or more.

  The magnetic toner contains a magnetic material. Examples of the magnetic material include ferromagnetic materials such as iron and cobalt, magnetite, hematite, Li-based ferrite, Mn-Zn-based ferrite, Cu-Zn-based ferrite, and Ni-Zn-based ferrite. Fine powders such as Ba-based ferrite can be used.

  To control the triboelectric chargeability, the toner is composed of a metal complex salt of monoazo dye, nitrohumic acid and its salt, salicylic acid, naphthoic salt, dicarboxylic acid such as Co, Cr, Fe, etc. You may contain charge control agents, such as dye.

  Further, the toner may contain a release agent as necessary. As the mold release agent, low molecular weight polypropylene, low molecular weight polyethylene, carnauba wax, microcrystalline wax, jojoba wax, rice wax, montanic acid wax and the like can be used alone or in combination.

The toner may contain other additives. In order to obtain a good image, it is preferable to impart fluidity to the toner. For this purpose, it is generally effective to add hydrophobized metal oxide particles and lubricant particles as fluidity improvers, and metal oxide, resin, metal soap and other particles as additives. Can be used. Specific examples of additives include fluororesins such as polytetrafluoroethylene, lubricants such as zinc stearate, abrasives such as cerium oxide and silicon carbide, inorganic oxides such as SiO ₂ and TiO ₂ having a hydrophobic surface, etc. Fluidity-imparting agents, known anti-caking agents and surface treated products thereof. In order to improve the fluidity of the toner, hydrophobic silica is particularly preferably used.

  The weight average particle diameter of the toner is preferably 3.0 to 9.0 μm, and more preferably 3.5 to 7.5 μm. The particle size of the toner can be measured using a Coulter counter (manufactured by Coulter Counter).

  The developer of the present invention preferably contains 2 to 25 parts by weight of toner and more preferably 3 to 20 parts by weight with respect to 100 parts by weight of carrier.

  FIG. 2 shows an example of an image forming apparatus used in the present invention, and the image forming method of the present invention will be described below. Around the photoreceptor 301, a charging device 302, an image exposure system 303, a developing device 304, a transfer device 305, a cleaning device 306, and a charge eliminating lamp 307 are arranged. The surface of the charging device 302 is not in contact with the surface of the photosensitive member 301 at a distance of about 0.2 mm, and is not shown in the charging device 302 when the charging device 302 charges the photosensitive member 301. By charging the photosensitive member 301 with an electric field in which an alternating current component is superimposed on a direct current component by voltage application means, it is possible to reduce charging unevenness and it is effective.

  A series of image forming processes can be described as a negative-positive process. The photosensitive member 301 is neutralized by a static elimination lamp 307, is negatively charged by a charging device 302 such as a charging charger or a charging roller, and a latent image is formed by laser light irradiated from an image exposure system 303 such as a laser optical system. .

  Laser light is emitted from a semiconductor laser and scans the surface of the photosensitive member 301 in the direction of the rotation axis of the photosensitive member 301 by a polygonal polygonal mirror (polygon) that rotates at high speed. The latent image formed in this way is developed with the developer of the present invention supplied onto the developing sleeve 304a of the developing device 304, and a toner image is formed. When developing the latent image, a DC voltage or a developing bias in which an AC voltage is superimposed on the DC voltage is applied between the developing sleeve 304a and the photosensitive member 301 from a voltage application mechanism (not shown).

  On the other hand, a transfer medium 308 such as paper is fed from a paper feed mechanism (not shown), and is synchronized with the leading edge of the image by a pair of upper and lower registration rollers (not shown). In between, the toner image is transferred. At this time, it is preferable that a potential having a polarity opposite to that charged with toner is applied to the transfer device 305 as a transfer bias. Thereafter, the transfer medium 308 is separated from the photoreceptor 301, and a transfer image is obtained.

  Further, the toner remaining on the photosensitive member 301 is collected by the cleaning blade 306 a of the cleaning device 306 into the toner collecting chamber 306 b in the cleaning device 306.

  The image forming apparatus may be an apparatus in which a plurality of developing devices 304 are arranged, and after sequentially transferring the toner images onto the transfer medium 308, the toner is fixed by heat or the like. It is also possible to use a device that transfers the image to the transfer medium 308 and then fixes it.

  FIG. 3 shows an example of the process cartridge of the present invention. The process cartridge of the present invention is configured by integrally combining at least the components including the photoconductor 301 and the developing device 304 among the components such as the photoconductor 301, the charging device 302, the developing device 304, and the cleaning device 306, It is configured to be detachable from the image forming apparatus main body such as a copying machine or a printer. At this time, in the developing device, development is performed using the developer of the present invention.

  Hereinafter, the present invention will be specifically described by way of examples. In addition, this invention is not limited to the Example illustrated here.

Hereinafter, the present invention will be described using examples and comparative examples. However, a part represents a weight part.
(Carrier production example 1)
To a mixed solution obtained by diluting 100 parts of silicone resin SR2411 (manufactured by Toray Dow Corning Silicone) and 50 parts of acrylic resin with toluene so that the solid content is 20% by weight, NH ₂ (CH ₂ ) ₃ Si (OCH ₃ ) is added. 1.5 parts was added, and 150 parts of toluene was further added to obtain a coating layer coating solution 1.

  Next, the coating layer coating solution 1 was applied to the core material particles 1 (see Table 1) at 50 g / min in an atmosphere at 80 ° C. using a fluid bed type coating apparatus. Furthermore, it heated at 200 degreeC for 2 hours, and obtained the carrier A whose average film thickness of a coating layer is 0.6 micrometer. The film thickness of the coating layer was measured by crushing the carrier and observing the cross section with a scanning electron microscope.

（キャリア製造例２）
５０部のシリコーン樹脂ＳＲ２４１１及びアクリル樹脂１００部を固形分が２０重量％となるようにトルエンで希釈した混合液に、ＮＨ_２（ＣＨ_２）_３Ｓｉ（ＯＣＨ_３）を１．５部添加し、さらにトルエンを１５０部添加して被覆層塗布液２を得た。

(Carrier production example 2)
1.5 parts of NH ₂ (CH ₂ ) ₃ Si (OCH ₃ ) is added to a mixed solution obtained by diluting 50 parts of silicone resin SR2411 and 100 parts of acrylic resin with toluene so that the solid content is 20% by weight, Further, 150 parts of toluene was added to obtain a coating layer coating solution 2.

Next, a carrier B having an average coating layer thickness of 0.6 μm was obtained in the same manner as in Carrier Production Example 1 except that the coating layer coating solution 2 was used.
(Carrier production example 3)
To a mixed solution obtained by diluting 95 parts of silicone resin SR2411 and acrylic resin 5 parts with toluene so that the solid content is 20% by weight, 1.5 parts of NH ₂ (CH ₂ ) ₃ Si (OCH ₃ ) is added, Further, 150 parts of toluene was added to obtain a coating layer coating solution 3.

Next, a carrier C having an average coating layer thickness of 0.6 μm was obtained in the same manner as in Carrier Production Example 1 except that the coating layer coating solution 2 was used.
(Carrier Production Examples 4 to 7)
Carriers D to G having an average coating layer thickness of 0.6 μm were obtained in the same manner as in Carrier Production Example 2 except that the core particles 2 to 5 (see Table 1) were used.
(Carrier Production Example 8)
12 parts of conductive carbon having a specific surface area of 1270 m ² / g was added to a mixture obtained by diluting 100 parts of silicone resin SR2411 and 50 parts of acrylic resin with toluene so that the solid content was 20% by weight, and 150 parts of toluene. A coating layer coating solution 4 was obtained by adding 30 parts and dispersing for 30 minutes with a homogenizer.

A carrier H having an average coating layer thickness of 0.6 μm was obtained in the same manner as in Carrier Production Example 1 except that the coating layer coating solution 4 was used.
(Carrier production example 9)
15 parts of alumina particles having an average particle diameter of 0.3 μm are added to a mixture obtained by diluting 100 parts of silicone resin SR2411 and 50 parts of acrylic resin with toluene so that the solid content becomes 20% by weight, and 150 parts of toluene. A coating layer coating solution 5 was obtained by adding 30 parts and dispersing for 30 minutes with a homogenizer.

A carrier I having an average coating layer thickness of 0.6 μm was obtained in the same manner as in Carrier Production Example 1 except that the coating layer coating solution 5 was used.
(Creation of sample corresponding to carrier A)
To a mixed solution obtained by diluting 100 parts of silicone resin SR2411 and acrylic resin 50 parts with toluene so that the solid content is 20% by weight, 1.5 parts of NH ₂ (CH ₂ ) ₃ Si (OCH ₃ ) is added, Further, 150 parts of toluene was added. This liquid was applied on a slide glass so that the film thickness was 10 μm, and heat-treated at 200 ° C. for 2 hours to prepare a sample corresponding to carrier A.
(Create sample corresponding to carrier B)
1.5 parts of NH ₂ (CH ₂ ) ₃ Si (OCH ₃ ) is added to a mixed solution obtained by diluting 50 parts of silicone resin SR2411 and 100 parts of acrylic resin with toluene so that the solid content is 20% by weight, Further, 150 parts of toluene was added. This liquid was applied on a slide glass so that the film thickness was 10 μm, and heat-treated at 200 ° C. for 2 hours to prepare a sample corresponding to carrier B.
(Creation of sample corresponding to carrier C)
To a mixed solution obtained by diluting 95 parts of silicone resin SR2411 and acrylic resin 5 parts with toluene so that the solid content is 20% by weight, 1.5 parts of NH ₂ (CH ₂ ) ₃ Si (OCH ₃ ) is added, Further, 150 parts of toluene was added. This liquid was applied on a slide glass so that the film thickness was 10 μm, and heat-treated at 200 ° C. for 2 hours to prepare a sample corresponding to carrier C.
(Creation of samples corresponding to carriers D to G)
1.5 parts of NH ₂ (CH ₂ ) ₃ Si (OCH ₃ ) is added to a mixed solution obtained by diluting 50 parts of silicone resin SR2411 and 100 parts of acrylic resin with toluene so that the solid content is 20% by weight, Further, 150 parts of toluene was added. This liquid was applied on a slide glass so as to have a film thickness of 10 μm and heat-treated at 200 ° C. for 2 hours to prepare samples corresponding to the carriers D to G.
(Creation of samples corresponding to carriers H and I)
750 parts of toluene was added to 100 parts of silicone resin SR2411 and 50 parts of acrylic resin. This liquid was applied on a slide glass so that the film thickness was 10 μm, and was heat-treated at 200 ° C. for 2 hours to prepare samples corresponding to carriers H and I.
(Evaluation method and evaluation results of elastic deformation rate and universal hardness)
The elastic deformation rate η _HU and universal hardness _HU of the samples corresponding to the carriers A to I were measured using a Fisherscope H100C. For the measurement, a Vickers indenter was used and the maximum load was 9.8 mN. Table 2 shows the evaluation results.

（キャリアの電気抵抗率の評価方法及び評価結果）
キャリアＡ〜Ｉをそれぞれセルに溢れるまで入れた後、セルを２０回タッピングし、非磁性の水平なヘラを用いてセルの上端に沿って一回の操作で平らに掻き取ることにより、充填した。次に、図１の抵抗測定セルを用いて、以下のようにして評価した。表面積２ｃｍ×４ｃｍの電極１０２ａ及び電極１０２ｂを電極間距離が２ｍｍとなるように収容したフッ素樹脂製のセル１０１にキャリア１０３を充填し、両極間に１００Ｖ（又は５００Ｖ）の直流電圧を印加し、ハイレジスタンスメーター４３２９Ａ（４３２９Ａ＋ＬＪＫ ５ＨＶＬＶＷＤＱＦＨ ＯＨＷＨＵ；横川ヒューレットパッカード社製）を用いて直流抵抗を測定し、電気抵抗率Ｒ（Ω・ｃｍ）を算出した。表３に評価結果を示す。

(Evaluation method and result of carrier electrical resistivity)
After each of the carriers A to I was filled into the cell, the cell was tapped 20 times and filled by scraping flat along the top edge of the cell with a nonmagnetic horizontal spatula in one operation. . Next, the resistance measurement cell of FIG. 1 was used for evaluation as follows. A carrier 103 is filled in a cell 101 made of fluororesin in which an electrode 102a and an electrode 102b having a surface area of 2 cm × 4 cm are accommodated so that the distance between the electrodes is 2 mm, and a DC voltage of 100 V (or 500 V) is applied between both electrodes, DC resistance was measured using a high resistance meter 4329A (4329A + LJK 5HLVLVWDQFH OHWHU; manufactured by Yokogawa Hewlett-Packard Company), and electric resistivity R (Ω · cm) was calculated. Table 3 shows the evaluation results.

（トナー製造例）
ポリエステル樹脂１００部、キナクリドン系マゼンタ顔料３．５部及び含フッ素４級アンモニウム塩４部を、ブレンダーを用いて混合した後、２軸式押出し機を用いて溶融混練した。放冷後、カッターミルを用いて粗粉砕し、ジェット気流式微粉砕機を用いて微粉砕し、さらに風力分級機を用いて分級して、重量平均粒径６．８μｍ、真比重１．２０のトナー母粒子を得た。

(Example of toner production)
100 parts of a polyester resin, 3.5 parts of a quinacridone magenta pigment, and 4 parts of a fluorine-containing quaternary ammonium salt were mixed using a blender, and then melt-kneaded using a twin-screw extruder. After standing to cool, it is coarsely pulverized using a cutter mill, finely pulverized using a jet airflow fine pulverizer, and further classified using an air classifier, and has a weight average particle diameter of 6.8 μm and a true specific gravity of 1.20. Toner mother particles were obtained.

Further, 0.8 part of hydrophobic silica fine particles R972 (manufactured by Nippon Aerosil Co., Ltd.) was added to 100 parts of toner base particles, and mixed with a Henschel mixer to obtain a toner.
Example 1
9.7 parts of toner was added to 100 parts of carrier A and stirred for 20 minutes with a ball mill to prepare a developer. The coverage of the toner with respect to the carrier was 50%.

The coverage of the toner with respect to the carrier is calculated by the following formula.
Coverage (%) = (Wt / Wc) × (ρc / ρt) × (Dc / Dt) × (1/4) × 100
Here, Wt is the weight (g) of the toner, Wc is the weight (g) of the carrier, ρc is the true density (g / cm ³ ) of the carrier, and ρt is the true density of the toner. (G / cm ³ ), Dc is the weight average particle diameter (μm) of the carrier, and Dt is the weight average particle diameter (μm) of the toner.
(Examples 2 to 8, Comparative Example 1)
A developer was prepared in the same manner as in Example 1 except that the carrier was changed as shown in Table 3.
(Image forming method)
Images were formed using the developers of Examples 1 to 8 and Comparative Example 1, and the image quality was evaluated. For image formation, a digital color copier / printer combined machine Imagio Color 5000 (manufactured by Ricoh) was used, and the following development conditions were used.
・ Development gap (photosensitive member-developing sleeve): 0.4 mm
・ Doctor gap (developing sleeve-doctor): 0.7mm
Photoconductor linear velocity: 245 mm / secondDevelopment sleeve linear velocity / photosensitive member linear velocity: 1.5
Write density: 600 dpi
・ Charging potential (Vd): -750V
-Potential after exposure of the portion corresponding to the image portion (solid document): -100V
Development bias: DC bias component: −500 V / AC bias component: 2 KHz, −100 V to −900 V, 50% duty
(Image evaluation method and evaluation results)
The test methods and evaluation criteria employed for image evaluation are shown below.
(1) Image Density The center of a solid portion of 30 mm × 30 mm under the above development conditions was measured at five locations using an X-Rite 938 spectrocolorimetric densitometer, and the average value was calculated.
(2) Granularity Granularity (brightness range: 50 to 80) defined by the following formula was measured.

Granularity = exp (aL + b) ∫ (WS (f)) ^1/2 · VTF (f) df
Here, L is the average brightness, f is the spatial frequency (cycle / mm), WS (f) is the power spectrum of the brightness variation, and VTF (f) is the visual spatial frequency characteristic. A and b are coefficients. The granularity is 0 or more and less than 0.1, ◎ (very good), 0.1 or more and less than 0.2, ◯ (good), 0.2 or more and less than 0.3, △ (usable), 0. Three or more were judged as x (unusable).
(3) Background stain The stain on the background on the image was visually evaluated. In addition, it was determined that 大 変 was very good, ○ was good, and x was bad.
(4) Carrier adhesion The charging potential (Vd) is fixed at -750 V, the developing bias (Vb) is fixed at -400 V DC, the background portion (unexposed portion) is developed, transferred from the photosensitive drum with adhesive tape, and 30 cm The number of carriers adhering to ² was counted to evaluate the carrier adhesion. In addition, it was determined that 大 変 was very good, ○ was good, and x was bad.
(5) Carrier adhesion after running 20,000 sheets For a developer that has run 20,000 sheets on a character image chart with an image area ratio of 6% while replenishing toner, adhere the carrier in the same way as (4). evaluated.

It is a perspective view of the resistance measurement cell used for the measurement of the electrical resistivity of the carrier in this invention. It is a figure which shows an example of the image forming apparatus used by this invention. It is a figure which shows an example of the process cartridge of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Cell 102a, 102b Electrode 103 Carrier 301 Photoconductor 302 Charging device 303 Image exposure system 304 Developing device 304a Developing sleeve 305 Transfer device 306 Cleaning device 306a Cleaning blade 306b Toner recovery chamber 307 Static elimination lamp 308 Transfer medium

Claims (12)

In a carrier having magnetic core material particles and a coating layer formed on the surface of the core material particles,
The coating layer contains a silicone resin,
The carrier characterized in that the elastic deformation rate of the resin component constituting the coating layer is 30% or more and 90% or less. The carrier according to claim 1, wherein the resin component has a universal hardness of 200 N / mm ² or more and 3000 N / mm ² or less. The weight average particle size is 22 μm or more and 32 μm or less,
The ratio of the weight average particle diameter to the number average particle diameter is 1.0 or more and 1.2 or less,
The content of particles having a particle size of less than 20 μm is 0 wt% or more and 7 wt% or less,
The carrier according to claim 1 or 2, wherein the content of particles having a particle size of less than 36 µm is 90 wt% or more and 100 wt% or less.   The carrier according to any one of claims 1 to 3, wherein the coating layer further contains an aminosilane coupling agent.   The carrier according to any one of claims 1 to 4, wherein the core particles have a magnetization in a magnetic field of 1 kOe of 70 emu / g or more and 150 emu / g or less. The carrier according to any one of claims 1 to 5, wherein the core particles have a bulk density of 2.35 g / cm ³ or more and 2.50 g / cm ³ or less. The electrical resistivity in an electric field of 50 V / mm is 1 × 10 ¹⁴ Ω · cm to 1 × 10 ¹⁷ Ω · cm,
The carrier according to any one of claims 1 to 6, wherein an electric resistivity in an electric field of 250 V / mm is 1 x 10 ⁸ Ω · cm or more and 1 x 10 ¹⁶ Ω · cm or less.   The carrier according to any one of claims 1 to 7, wherein the coating layer contains hard particles.   The carrier according to claim 8, wherein the hard particles contain at least one of an oxide of silicon, an oxide of titanium, and an oxide of aluminum.   A developer comprising the carrier and toner according to any one of claims 1 to 9.   An image forming method comprising: developing at least an electrostatic latent image formed on the surface of a photoreceptor using the developer according to claim 10.   11. A process cartridge comprising: at least a photosensitive member and a developing unit that develops the electrostatic latent image formed on the surface of the photosensitive member using the developer according to claim 10 integrally.

Images