JP2006047697A - Carrier for electrostatic latent image developer, electrostatic latent image developer, and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To extremely reduce the wear and peeling of a carrier coated resin. <P>SOLUTION: The carrier for an electrostatic latent image developer has a coated resin layer on a core material, wherein the core material is formed by dispersing ferromagnetic particulates into a phenolic resin; the coated resin layer is composed of one or two or more kinds of ionomer resins selected from a polyurethane-based ionomer resin, polyester-based ionomer resin, and acrylic-based ionomer resin; and the tensile strength of the ionomer resins is 30 to 200 MPa: the tensile break elongation of the ionomer resins is 100 to 500%. The developer is composed of the above carrier and the toner. The image forming method uses such developer. The development apparatus of a small size and low cost does not require a toner density sensor and a toner replenishing mechanism, wherein the electrification impartation to the toner is sufficiently executed, and satisfactory image quality free of toner scattering, surface staining and picture void, etc., can be obtained and maintained for a long period. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electrostatic latent image developer carrier, an electrostatic latent image developer, and an image forming method used when developing an electrostatic latent image formed by an electrophotographic method, an electrostatic recording method, or the like.

  A method for visualizing image information through an electrostatic latent image, such as electrophotography, is currently used in various fields. In electrophotography, an electrostatic latent image is formed on a photoconductor in a charging and exposure process, the electrostatic latent image is developed with a developer containing toner, and visualized through a transfer and fixing process. The developer used here includes a two-component developer composed of a toner and a carrier, and a one-component developer used alone such as a magnetic toner. The two-component developer is a carrier in which the developer is stirred and conveyed. It is currently widely used because it shares functions such as charging and functions are separated as a developer, so that controllability is good.

  There are various characteristics required for the carrier, but the toner can be provided with appropriate chargeability (charge amount, charge distribution, polarity), stable charging characteristics with respect to environmental changes, There is a particular demand for maintaining appropriate and stable chargeability over a long period of time. In order to satisfy these required characteristics, a carrier in which a core material is coated with various resins has been studied. As a result, among the required characteristics, considerable improvement has been seen in chargeability and environmental stability of charging. On the other hand, in terms of charge maintenance, the developer life is considerably inferior to the machine life, and the developer is frequently changed at present. Therefore, it is considered that the long-life charging property is the most required characteristic.

  The main causes of carrier deterioration include contamination of the toner component on the surface of the carrier coating resin and wear / peeling of the coating resin. The abrasion / peeling of the coating resin is a phenomenon in which the coating resin layer is pulled by an impact force or frictional force between carriers or between the carrier and the toner in the developing device, and is broken or peeled off from the core material. In addition, the contamination of the toner component is caused by the external additive added to the toner moving to the carrier surface due to the impact force or frictional force between the carrier and the toner and buried in the coating resin layer, or the toner itself rubs against the carrier surface. It is a phenomenon of fusing by heat. The use of low surface energy resins such as fluororesins and silicone resins has been actively investigated for contamination of toner components, and their effectiveness has been confirmed. However, these low surface energy resins are adhesive to the core material. Also, the brittleness of the resin itself is difficult, and the problem of wear and peeling of the coating resin has not been improved sufficiently.

  Wear and peeling of the coating resin is not only due to deterioration of the carrier, but also part of the worn or peeled coating resin is mixed in the toner, and the coating resin that is worn or peeled off during fixing is the fixing roll. The fixing roll may be contaminated by adhering to the surface, and image defects such as an image defect may occur. In particular, as the machine speed increases, the fixing temperature also increases, and it is easy to cause fouling of the fixing roll due to worn or peeled coating resin and image defects due to it. It is.

  In Patent Document 1, Patent Document 2, Patent Document 3, and Patent Document 4, low specific gravity in which ferromagnetic fine particles are dispersed in a phenol resin in order to reduce the impact force and friction force between carriers or between a carrier and a toner. Carriers using a core material and coated with various resins on the core material have been proposed. However, since the adhesion between the phenolic resin and the coating resin of the core material is not sufficient, the peeling of the coating resin is not sufficiently improved, and the life equivalent to the machine life is not achieved.

  Many electrophotographic processes have been known. In the electrophotographic process, a latent image is electrically formed on the electrostatic latent image holding member using a photoconductive substance by various means, and the latent image is developed with toner to hold the electrostatic latent image. The toner image on the body is transferred to a transfer medium such as paper with or without an intermediate transfer medium, and then the transfer image is fixed by heating, pressing, heating and pressing, or solvent vapor. A fixed image is formed through a plurality of processes. The toner remaining on the electrostatic latent image holding member is cleaned by various methods as necessary, and the plurality of steps are repeated. Printers and copiers using an electrophotographic process have become widespread, and requirements for performance and image quality have become stricter year by year.

  The development system in the electrophotographic process is a one-component development system that uses only toner that is colorant particles as a developer, and a two-component development system that uses a mixture of magnetic particles and toner that is color particles as a developer. It is roughly divided into

  2. Description of the Related Art Conventionally, as a two-component developing type developing device, there are many excellent points such as image quality, cost, and stability. Therefore, there is a magnetic brush developing method in which a developer in which toner is mixed in a magnetic carrier is conveyed and developed by a magnetic field. Widely used. In this magnetic brush development method, the toner is supported on the surface of the magnetic carrier by the electrostatic force generated by the friction between the toner and the magnetic carrier. When this toner approaches the electrostatic latent image on the image carrier, The electrostatic latent image is formed into a visible image by flying onto the electrostatic latent image by an electric field formed by the electrostatic latent image. Further, the developer is repeatedly used while replenishing the toner consumed by the development. However, in such a magnetic brush developing method, if the toner concentration (mixing ratio of toner and magnetic carrier) is not controlled to be within a certain range, toner scattering and fogging occur when the toner concentration increases. On the other hand, when the toner density is reduced, density reduction, density spots, image omission, and the like occur. Therefore, it is necessary to keep the toner density constant in order to obtain a stable image.

  Therefore, in the conventional magnetic brush development method, in order to obtain a stable image, the toner density is detected using a toner density sensor, or a development patch is created to detect the toner development amount. Control is performed to keep the toner density constant by actuating it. For example, the toner density is detected by the toner density sensor, and after determining that the toner density has decreased based on the detection information, the toner supply is performed by the toner supply member. However, in this type of magnetic brush developing method, a toner density sensor and a toner replenishing member that can be independently driven ON / OFF are indispensable, and an increase in the size and cost of the developing device cannot be avoided. In addition, there is a problem that the toner density detection system is troublesome, such as creating a density patch to be detected.

  As a prior art for solving such problems, there has already been proposed a developing device that maintains a constant toner concentration without using a toner concentration sensor or a toner replenishing member. The developing device includes a developer accommodating portion that accommodates a two-component developer, and a toner accommodating portion that communicates with the developer accommodating portion and accommodates toner, and the amount of the two-component developer on the developer carrier is set. The toner density is adjusted by regulating by the regulating member and autonomously controlling the toner intake of the two-component developer by changing the toner density of the two-component developer on the developer carrier.

  This autonomous control method generates a developer moving layer carried and conveyed by a developer carrier and a developer circulation layer in which the developer circulates in the developer container, and communicates with the developer container. The toner is taken in from the toner container. In other words, when the toner is consumed in the developing process, the volume of the developer stored in the developer container is reduced, and the reduced amount of toner is supplied from the toner container to the developer container. In other words, the developer in the developer container holds the toner concentration.

  As an example of the developing device, in Patent Document 5, a magnetic particle layer is formed on a developing sleeve, and toner is accommodated in the toner supply unit in the container so as to be in contact with the magnetic particle layer, and accompanying the rotation of the developing sleeve. By the movement of the magnetic particles in the magnetic particle layer, the toner supply unit takes in the toner from the outer toner layer into the magnetic particle layer, and the thickness of the developer in which the toner and the magnetic particles are mixed is regulated by the regulating member. By transporting the toner to the developing unit, insufficient charging due to excessive supply of toner is prevented.

  Further, in Patent Document 6, in a developing sleeve rotating magnetic brush developing device having an internal magnetic pole, an insulating layer is provided on the surface of the developing sleeve, a toner supply roll is provided near the developing sleeve, and the toner supply roll and the developing sleeve are provided. By applying an alternating voltage between them, the toner concentration and toner charging are stabilized.

  Furthermore, in Patent Document 7, magnetic toner is used as the toner constituting the developer, thereby stabilizing toner charging and preventing toner scattering. Further, in Patent Document 8, the toner density is configured to be equal to or lower than the limit toner density at which the toner is completely covered on the surface of one carrier when the developer carrying speed is the fastest. In this way, it is intended to prevent background contamination and toner scattering.

  Further, in Patent Document 9, in the developer accommodating portion, the second upstream of the developer carrying member in the developer carrying direction with respect to the developer carrying member relative to the first regulating member that regulates the amount of developer carried and carried by the developer carrying member. By providing the regulating member, the toner density adjustment is stabilized.

Japanese Patent Laid-Open No. 3-192268 JP-A-4-86749 JP-A-11-125933 Japanese Patent Laid-Open No. 2000-39740 Japanese Patent Publication No. 5-67233 (page 1-3, Fig. 1) JP-A-5-119625 (page 1-5, FIG. 1) Japanese Patent Laid-Open No. 9-22178 (page 3-7, FIG. 1) JP 2000-352877 A (page 3-6, FIG. 1) Japanese Laid-Open Patent Publication No. 9-197833 (page 6-10, FIG. 1)

  However, the conventional developing method for autonomously controlling the toner density described above controls the toner density by changing the volume of the developer and the movement of the developer according to the change in the toner density. The movement of the developer must be remarkable. For this reason, it is necessary to reduce the amount of developer charged as compared with the two-component development system equipped with a normal toner density sensor or the like. When the developer charge is reduced, the stress applied to one carrier particle, specifically, the impact force or friction force between carriers or between carrier and toner increases. In addition, the developing method for autonomously controlling the toner density as described above often charges the toner by regulating the developer with a layer thickness regulating member as in Patent Document 5 described above. It is necessary to increase the regulation to impart the same, and the stress applied to the carrier particles also increases here. Thus, when the stress applied to the carrier particles is increased, the contamination of the toner component on the surface of the carrier coating resin and the wear / peeling of the coating resin become remarkable. The abrasion / peeling of the coating resin is a phenomenon in which the coating resin layer is pulled by an impact force or frictional force between carriers or between the carrier and the toner and is broken or peeled off from the core material. In addition, the contamination of the toner component is caused by the external additive added to the toner moving to the carrier surface due to the impact force or frictional force between the carrier and the toner and buried in the coating resin layer, or the toner itself on the carrier surface. It is a phenomenon of fusing by frictional heat. Due to the contamination of the toner component on the surface of the carrier coating resin and the wear / peeling of the coating resin, the charge imparting ability of the carrier deteriorates with time of use, and as a result, toner scattering and soiling become conspicuous.

  Wear and peeling of the coating resin is not only due to deterioration of the carrier, but also part of the worn or peeled coating resin is mixed in the toner, and the coating resin that is worn or peeled off during fixing is the fixing roll. The fixing roll may be contaminated by adhering to the surface, and image defects such as an image defect may occur. In particular, as the machine speed increases, the fixing temperature also increases, and it is easy to cause fouling of the fixing roll due to worn or peeled coating resin and image defects due to it. It is.

  Therefore, the present invention solves the above problems, imparts a sufficient charge amount to the toner, is stable against environmental fluctuations, and can maintain these charging characteristics and good image quality over a long period of time. Carrier, electrostatic latent image developer, and image forming method using them.

  In addition, in view of the above-described problems, the present invention can sufficiently charge the toner in a small and low-cost developing device that does not require a toner concentration sensor or a toner replenishment mechanism, and the toner scattering, background contamination, It is an object of the present invention to provide an image forming method capable of obtaining a good image quality without image blurring and maintaining it over a long period of time.

  As a result of diligent research to improve the above-described problems, the present inventors can impart an appropriate charge amount to the toner, exhibit stable charging characteristics against changes in the environment, The present inventors have found a resin-coated carrier that can maintain stable chargeability over a long period of time. That is, the present invention has succeeded in solving the above problems by adopting the following configuration.

  (1) In the carrier for an electrostatic latent image developer having a coating resin layer on a core material, the core material is formed by dispersing ferromagnetic fine particles in a phenol resin. It consists of one or more ionomer resins selected from ionomer resins, polyester ionomer resins, and acrylic ionomer resins. The tensile strength of the ionomer resin is 30 MPa or more and 200 MPa or less. , 100% or more and 500% or less carrier for electrostatic latent image developer.

  (2) The carrier for an electrostatic latent image developer according to the above (1), wherein the resin in the core material is a phenol resin obtained by reacting and curing phenols and aldehydes in an aqueous medium.

  (3) The carrier for an electrostatic latent image developer according to the above (1), wherein the carrier is produced by applying the ionomer resin dispersed in an aqueous medium onto the core material.

  (4) In the electrostatic latent image developer comprising a toner and a carrier, the toner has a shape factor SF1 of 100 or more and 140 or less, and the carrier is for the electrostatic latent image developer described in (1) above. An electrostatic latent image developer as a carrier.

  (5) A step of forming a latent image on the latent image carrier, a step of developing the latent image using a developer, a step of transferring the developed toner image to a transfer member, and a toner image on the transfer member And an image forming method using the electrostatic latent image developer described in (4) above as the developer.

  (6) a developer carrying member having a magnetic field generating means therein and carrying and carrying a two-component developer containing toner and a magnetic carrier; a toner containing unit communicating with the developer containing unit and containing toner; The amount of the two-component developer on the developer carrier is regulated by a regulating member, and the toner intake of the two-component developer is autonomously performed by changing the toner concentration of the two-component developer on the developer carrier. An image forming method for forming an image using a developing device having a mechanism for controlling the toner, wherein the toner is a magnetic toner containing at least a binder resin and a magnetic material, and the magnetic carrier is formed on a core material. The core material is formed by dispersing ferromagnetic fine particles in a phenol resin, and the coating resin layer is made of a polyurethane ionomer resin or a polyester ionomer. It consists of one or more ionomer resins selected from resins and acrylic ionomer resins, the ionomer resin has a tensile strength of 30 MPa to 200 MPa, and the ionomer resin has a tensile fracture elongation of 100% to 200%. An image forming method.

  (7) In the image forming method described in (6) above, the resin in the core material of the carrier is a phenol resin obtained by reacting and curing phenols and aldehydes in an aqueous medium.

  (8) In the image forming method according to the above (6) or (7), the carrier is manufactured by applying the ionomer resin dispersed in an aqueous medium onto the core material.

  (9) In the image forming method according to any one of (6) to (8), a step of forming an electrostatic latent image on the electrostatic carrier, and a developer on the electrostatic carrier It includes a step of forming a toner image, a step of transferring the toner image onto the transfer body, and a fixing step of heating and fixing the toner image on the transfer body.

  By adopting the above-described configuration, the present invention can extremely reduce contamination by the toner component on the surface of the carrier coating resin layer and wear / peeling of the carrier coating resin over a long period of time, resulting in a high fixing temperature. Even in this case, it is possible to prevent fouling of the fixing device and image defects due to this, and image defects such as fogging due to a decrease in charge amount. In addition, it is possible to provide an electrophotographic image having excellent halftone reproducibility and good image quality over the long term.

  Even with a developing device that does not use a toner density sensor or a toner replenishing member, the use of the developer of the present invention maintains excellent image quality without deterioration in image density, background contamination, image defects, etc. over a long period of time. It is possible to provide a developing device with high reliability and an image forming method using the developing device.

[Career]
The carrier of the present invention uses as a core a material formed by dispersing ferromagnetic fine particles in a phenol resin, and is selected from polyurethane ionomer resin, polyester ionomer resin, and acrylic ionomer resin on the core material. And one or more ionomer resins coated.

  The core material used in the present invention is obtained by reacting phenols and aldehydes in an aqueous medium in the presence of a basic catalyst in the presence of ferromagnetic fine particles and a suspension stabilizer. A production example of this is described in detail in JP-A-3-192268 and the like.

  As phenols used here, in addition to phenol, alkylphenols such as m-cresol, p-tert-butylphenol, o-propylphenol, resorcinol, bisphenol A, and a part or all of the benzene nucleus or alkyl group are included. Although compounds having a phenolic hydroxyl group such as halogenated phenols substituted with a chlorine atom or a bromine atom are mentioned, phenol is most preferred. When a material other than phenol is used, particles are difficult to produce, or even if particles are produced, they may have an indefinite shape, and phenol is most preferred.

  Examples of aldehydes used in the present invention include formaldehyde and furfural in the form of either formalin or paraformaldehyde, and formaldehyde is particularly preferable. The molar ratio of aldehydes to phenols is preferably 1 to 2, particularly preferably 1.1 to 1.6. If the molar ratio of aldehydes to phenols is less than 1, particles are difficult to produce, or even if particles are produced, the resin is hard to progress, so the strength of the particles produced tends to be weak, On the other hand, when the molar ratio of aldehydes to phenols is larger than 2, unreacted aldehydes remaining in the aqueous medium after the reaction tend to increase.

  As a basic catalyst used by this invention, the basic catalyst used for normal resole resin manufacture is used. For example, ammonia water, hexamethylenetetramine, alkylamines such as dimethylamine, diethyltriamine, and polyethyleneimine are listed. The molar ratio of these basic catalysts to phenols is preferably 0.02 to 0.3.

  Examples of the ferromagnetic fine particles used in the present invention include ferromagnetic oxides such as magnetite and ferrite, ferromagnetic metals such as iron, cobalt, and nickel, and other magnetic compounds or alloys. Further, the particle diameter of the ferromagnetic fine particles is preferably from 0.01 to 10 μm, and particularly preferably from 0.05 to 5 μm from the viewpoint of dispersion stability in an aqueous medium and strength of generated particles.

  Suspension stabilizers used in the present invention include hydrophilic organic compounds such as carboxymethyl cellulose and polyvinyl alcohol, fluorine compounds such as calcium fluoride, and substantially water-insoluble inorganic salts such as calcium sulfate. Among them, calcium fluoride is preferable from the viewpoint of dispersibility of the ferromagnetic fine particles inside the phenol resin. The addition amount of the suspension stabilizer is preferably 0.2 to 10% by weight, more preferably 0.5 to 3.5% by weight, based on the phenols. When the added amount of the suspension stabilizer is less than 0.2% by weight, amorphous particles tend to be formed. On the other hand, when the added amount exceeds 10% by weight, the suspension stability remaining on the particle surface is increased. The amount of the agent tends to increase, which is not preferable.

  The manufacturing method of the core material used by this invention is demonstrated. A reaction vessel is charged with phenols, aldehydes, water, ferromagnetic fine particles, and a suspension stabilizer, and after sufficiently stirring, a basic catalyst is added and the temperature is increased while stirring to raise the reaction temperature to 70 to 90 ° C. To adjust the phenolic resin. At this time, in order to obtain particles with high sphericity, it is necessary to raise the temperature gently, preferably 0.5 to 1.5 ° C./min, more preferably 0.8 to 1.2 ° C./min. . Thereafter, the cured reaction product is cooled to 40 ° C. or lower, and the obtained aqueous dispersion is separated by solid and liquid by a conventional method such as filtration and centrifugation, then washed and dried, and used in the present invention. A core material is obtained.

  The content of the ferromagnetic fine particles in the core material used in the present invention is 80 to 99% by weight. When the content of the ferromagnetic fine particles is less than 80% by weight, the saturation magnetization value becomes small, and when it exceeds 99% by weight, the binding between the ferromagnetic fine particles by the phenol resin becomes weak. By adjusting the content of the ferromagnetic fine particles within this range, a saturation magnetization value of 40 to 150 emu / g can be obtained while the saturation magnetization value of a conventionally known ferrite carrier is about 70 emu / g. . Further, by adjusting the content of the ferromagnetic fine particles within this range, the true specific gravity of the core material can be kept between 2.0 and 4.0, and the true specific gravity of a conventionally known ferrite carrier is 4.5. The specific gravity can be made considerably lower than that of .about.5.5. As a result, the impact force and friction force between carriers or between carrier and toner can be reduced as compared with conventionally known ferrite carriers. The saturation magnetization value described above is obtained by measurement using a vibrating sample magnetometer (manufactured by Toei Kogyo Co., Ltd.) under the condition of an applied magnetic field of 3000 (Oe).

  The resin coated on the core material in the present invention is one or more ionomer resins selected from polyurethane ionomer resins, polyester ionomer resins, and acrylic ionomer resins.

  An ionomer resin is obtained by ion-crosslinking between polymer chains with metal ions, and there is a resin having extremely excellent mechanical properties due to this specific chemical structure. The ionomer resin used in the present invention is particularly characterized by tensile strength and tensile fracture elongation, characterized by a tensile strength of 30 MPa or more and 200 MPa or less, and a tensile fracture elongation of 100% or more and 500% or less. . By coating the carrier with an ionomer resin having a tensile strength of 30 MPa or more and a tensile breaking elongation of 100% or more, the impact force and friction force between the carriers or between the carrier and the toner are alleviated, and the coating resin is worn and peeled off. And contamination of the toner component on the surface of the carrier coating resin layer is reduced. In general, tensile strength and tensile elongation at break have a trade-off relationship, and in order to achieve the above-described lower limit, it is necessary to set the upper limit value or less. Further, when any one of the tensile strength and the tensile breaking elongation is lower than the lower limit value, a sufficient effect is not observed. In particular, by combining the carrier core material having a low specific gravity and the ionomer resin, relaxation of the impact force and friction force between the carriers or between the carrier and the toner is accelerated. The evaluation methods for tensile strength and tensile breaking elongation are evaluated according to JIS standards (K7113, plastic tensile test method).

  Regarding the polyurethane ionomer resin used in the present invention, (1) an organic solvent solution of a hydrophilic group-containing polyurethane resin obtained by reacting a hydrophilic group-containing compound, another active hydrogen-containing compound, and a polyisocyanate. Alternatively, a method of obtaining an ionomer resin by emulsifying an organic solvent dispersion in water, (2) a hydrophilic group-containing terminal isocyanate obtained by reacting a hydrophilic group-containing compound, another active hydrogen-containing compound, and a polyisocyanate Examples thereof include a method of obtaining an ionomer resin by dispersing a group-containing urethane prepolymer in water and reacting with a polyamine.

  Examples of the hydrophilic group-containing compound include sulfonic acid-containing compounds such as 2-oxyethanesulfonic acid, sulfosuccinic acid, sulfanilic acid, and 2,4-diaminotoluenesulfonic acid, 2,2-dimethylolpropionic acid, and dioxymalein. Examples thereof include acids, carboxylic acid-containing compounds such as 3,4-diaminobenzoic acid, polyoxyethylene glycol or polyoxyethylene-polyoxypropylene copolymer glycol having at least one active hydrogen in the polymer, and the like.

  Examples of the other active hydrogen-containing compounds include low molecular weight compounds such as polyester polyols and polyether polyols, polyoxy compounds typified by glycerin and trimethylolpropane, diamine compounds typified by ethylenediamine and piperazine, and the like. A molecular weight compound is mentioned.

  Examples of the polyisocyanate include 2,4-tolylene diisocyanate, phenylene diisocyanate, 4,4-diphenylmethane diisocyanate, 1,6-hexamethylene diisocyanate, and isophorone diisocyanate.

  These reactions can be performed in the absence of a solvent, but may be performed in an organic solvent. The obtained resin is neutralized with non-volatile bases such as caustic soda and caustic potash, amines such as triethylamine and dimethylethanolamine, or ammonia, and an ionomer resin is obtained by adding water.

  The polyurethane ionomer resin thus obtained may be used as it is, but may be used after removing an organic solvent by distillation if necessary. Examples of commercially available polyurethane ionomer resins include “Hydran” [manufactured by Dainippon Ink & Chemicals, Inc.].

  Regarding the polyester ionomer resin used in the present invention, (1) a copolycondensation of a dicarboxylic acid having an alkali metal sulfonate with an aromatic nucleus, and (2) a polycarboxylic acid anhydride added to the polyester with a base. Examples include neutralized ones, (3) those obtained by copolycondensation of polyethylene glycol, and combinations thereof.

  Examples of the dicarboxylic acid having a sulfonic acid alkali metal salt in the aromatic nucleus include alkali metal salts such as sulfoterephthalic acid, 5-sulfoisophthalic acid, and 4-sulfonaphthalene-2,7 dicarboxylic acid. Also included are ester-forming derivatives used in ordinary polyester production, such as methyl esters of these carboxylic acids, lower alcohol esterified products such as ethyl esters.

  Other carboxylic acids include terephthalic acid, isophthalic acid, phthalic anhydride, 2,6-naphthalenedicarboxylic acid, biphenyldicarboxylic acid, trimellitic anhydride, pyromellitic anhydride and other aromatic carboxylic acids, and their ester formation And aliphatic derivatives such as succinic acid, maleic acid, fumaric acid, adipic acid, pimelic acid, sebacic acid, dimer acid and cyclohexanedicarboxylic acid, and ester-forming derivatives thereof.

  Moreover, it does not specifically limit about a polyol component, All the polyols normally used for a polyester resin can be used. Examples of the polyol include ethylene glycol, diethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, 1,4-cyclohexanediol, hydrogenated bisphenol A, polyoxyethylene glycol, polyoxy Examples include propylene glycol, glycerin, trimethylolethane, pentaerythritol and the like.

  In the case of water dispersion of such a polyester, when there are a large amount of sulfonic acid alkali metal salt or polyethylene glycol, it is dispersed in water only by stirring in warm water, but when these components are small, a small amount of methanol, ethanol, Alcohols such as propanol and butanol, ketones such as methyl ethyl ketone and methyl isobutyl ketone, glycols and cellosolves can be added and dispersed in water.

  Examples of commercially available polyester ionomer resins include “Finetex-ES” series [manufactured by Dainippon Ink & Chemicals, Inc.].

  For the acrylic ionomer resin used in the present invention, (1) an ethylenically unsaturated monomer mixture containing an ethylenically unsaturated carboxylic acid monomer and / or an ethylenically unsaturated sulfonic acid monomer is organically A method of copolymerization using a radical polymerization initiator in the presence of a solvent and adding a base and water to the obtained copolymer to obtain an ionomer resin, (2) an ethylenically unsaturated carboxylic acid monomer or / and The ethylenically unsaturated monomer mixture containing the ethylenically unsaturated sulfonic acid monomer is subjected to suspension polymerization using a radical polymerization initiator in water in the presence of a dispersant, the copolymer is isolated, and then the base and The method etc. which add ionomer resin by adding water are mentioned.

  Examples of the ethylenically unsaturated carboxylic acid monomer include monocarboxylic acids such as acrylic acid and methacrylic acid, dicarboxylic acids such as itaconic acid, fumaric acid, maleic acid, and crotonic acid, and anhydrides and monoesters thereof. Can be mentioned. Examples of the ethylenically unsaturated sulfonic acid monomer include sulfonic acids such as styrene sulfonic acid and vinyl sulfonic acid, and salts thereof.

  As the ethylenically unsaturated monomer, a monomer used in a known general acrylic resin can be used. For example, (meth) acrylate such as methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, β-hydroxy (meth) acrylate, glycidyl (meth) acrylate, acrylamide, N -Ethylenically unsaturated monomers having a functional group such as methylolacrylamide, and ethylenically unsaturated monomers copolymerizable with these such as styrene, acrylonitrile, and butadiene.

  Examples of the base include amines such as triethylamine, dimethylethanolamine, methyldiethanolamine, triethanolamine, and morpholine, and alkali metal or alkaline earth metal water such as ammonia, sodium hydroxide, potassium hydroxide, and barium hydroxide. An oxide etc. are mentioned.

  Commercially available acrylic ionomer resins include, for example, “Watersol” series [Dainippon Ink Chemical Co., Ltd.], “Finetex” series [Dainippon Ink Chemical Co., Ltd.], “Dick Fine” series. [Dainippon Ink Chemical Co., Ltd.].

  As the metal ion (metal cation species) in any ionomer resin described above, alkali metals such as sodium and potassium are preferable.

  The present inventors applied the aqueous dispersion of the above ionomer resin on a carrier core material using a phenol resin as a binder resin, and then dried (removed water) to form a coating layer. It has been found that the adhesion between the core material and the coating layer becomes extremely high. For this reason, it turned out that peeling of coating resin is further eased. The cause of the high adhesion between the carrier core material and the coating layer has not been clarified, but the phenol resin was obtained by reaction-curing phenols and aldehydes in an aqueous medium as described above. Therefore, it is considered hydrophilic. On the other hand, any of the ionomer resins described above is an ionic polymer having an acid group (such as carboxylic acid or sulfonic acid) in the polymer chain and neutralizing the acid group with a metal ion or a metal cation species. It is hydrophilic. Therefore, since both are hydrophilic to each other, it is considered that the affinity is better. Further, since the ionomer resin has hydrophilic groups such as carboxyl groups and sulfonic acid groups oriented with respect to the phenol resin of the carrier core material, it is expected that the affinity is improved and the adhesion is improved. For this reason, it is expected that the affinity between the ionomer resin and the phenol resin in the aqueous medium is extremely good. As an example to support this, there is an example of an aqueous dispersion of a phenol resin (JP-A-7-97504). Here, an extremely stable aqueous dispersion is obtained by adding the ionomer resin as a polymer dispersant to the aqueous dispersion of the phenol resin, and the cured product obtained from the aqueous dispersion is brittle. Thus, a composition having improved toughness and excellent toughness has been obtained.

  Examples of the method of coating the ionomer resin on the carrier core material include an immersion method in which the carrier core material is immersed in an aqueous dispersion of ionomer resin, a spray method in which an aqueous dispersion of ionomer resin is sprayed on the surface of the carrier core material, and a carrier. Fluidized bed method in which an ionomer resin aqueous dispersion is sprayed in a state where the core material is floated by flowing air, and a kneader coater method in which the carrier core material and the ionomer resin aqueous dispersion are mixed to remove water in the kneader coater. can give.

  In the coating layer of the present invention, resin fine particles can be dispersed for the purpose of adjusting the charge amount. Specific examples of the resin fine particles include amino resins such as phenol resins, urea-formaldehyde resins, melamine resins, benzoguanamine resins, urea resins and polyamide resins; crosslinked silicone resins; fluororesins. The volume average particle diameter of the resin fine particles is preferably 0.1 to 2 μm, more preferably 0.2 to 1 μm. If the thickness is smaller than 0.1 μm, the dispersion in the coating resin layer is poor, and if it is larger than 2 μm, the coating resin layer is likely to fall off and the original function cannot be maintained. The addition amount of the resin fine particles is 1 to 50% by weight, preferably 5 to 30% by weight in the coating resin layer.

  In the present invention, the conductivity of the carrier can be increased by dispersing conductive powder in the coating layer. In general, when a resin coating is applied, the carrier is insulated and becomes difficult to function as a developing electrode during development, so that the solid reproducibility is deteriorated, for example, an edge effect is produced in a solid image portion. Therefore, it is possible to improve them by dispersing conductive powder in the coating layer.

The electric resistance of the conductive powder itself is preferably 10 ⁸ Ωcm or less, and more preferably 10 ⁵ Ωcm or less. Specific examples of conductive powder include metals such as gold, silver and copper; carbon black; conductive metal oxides such as titanium oxide and zinc oxide; titanium oxide, zinc oxide, aluminum borate and titanic acid. Examples thereof include a composite system in which the surface of fine particles such as potassium and tin oxide are coated with a conductive metal oxide. Carbon black is particularly preferable from the viewpoints of production stability, cost, and low electrical resistance. The type of carbon black is not particularly limited, but those having a DBP (dibutyl phthalate) oil absorption in the range of 50 to 300 ml / 100 g with good production stability are preferred. The conductive powder preferably has a volume average particle size of 0.1 μm or less, and preferably has a primary particle size of 50 nm or less for dispersion.

  The coating amount of the coating layer on the carrier core material is suitably in the range of 0.3 to 5% by weight with respect to the carrier weight.

[toner]
The carrier of the present invention is mixed with an appropriate granular toner and used as an electrostatic latent image developer. The toner used in the present invention is preferably produced by a wet method, and the shape factor SF1 is preferably 100 or more and 140 or less. The shape factor SF1 can be obtained by the following equation.

SF1 = (ML ² / A) × (π / 4) × 100

Here, ML is an average value of absolute maximum lengths of particles, A is a projected area of particles, and these are quantified mainly by analyzing a microscope image or an operation electron microscope image with an image analyzer.

  The volume average particle diameter of the toner tends to be reduced with an increase in image quality, and a range of 2 to 12 μm, preferably 3 to 10 μm is appropriate.

  For the production of toner, for example, (i) a kneading and pulverizing method in which a binder resin, a colorant, a release agent, and a charge control agent, if necessary, are melt-kneaded, pulverized, and classified; (Iii) a resin fine particle dispersion obtained by emulsion polymerization of a binder resin polymerizable monomer, a colorant, a release agent, and a necessary method And an emulsion polymerization agglomeration method in which toner particles are obtained by mixing with a dispersion liquid in which a charge control agent or the like is dispersed according to the conditions, agglomerating and heat-fusing, and (iv) a polymerizable monomer for obtaining a binder resin And suspension polymerization method in which a solution such as a colorant, a release agent, and a charge control agent is suspended in an aqueous solvent for polymerization, and (v) a binder resin and a colorant, a release agent, if necessary For example, a solution suspension method in which a solution such as a charge control agent is suspended in an aqueous solvent and granulated can be employed. Further, the toner obtained by these methods may be used as a core, and agglomerated particles may be further adhered and heat-fused to obtain a core-shell toner.

  As the binder resin for the toner, styrenes such as styrene and chlorostyrene; monoolefins such as ethylene, propylene, butylene, and isoprene; vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzoate, and vinyl acetate; methyl acrylate , Α-methylene aliphatic monocarboxylic acid esters such as ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, dodecyl methacrylate; Homopolymers or copolymers of vinyl ethers such as ether, vinyl ethyl ether, vinyl butyl ether; vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, vinyl isopropenyl ketone, etc. Typical binder resins include polystyrene, styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer. Examples thereof include coalescence, polyethylene, and polypropylene. Further examples include polyester, polyurethane, epoxy resin, silicon resin, polyamide, modified rosin, and paraffin waxes.

  Examples of colorants include carbon black, nigrosine, aniline blue, calcoil blue, chrome yellow, ultramarine blue, dupont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green oxalate, lamp black, rose bengal, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 57: 1, C.I. I. Pigment yellow 97, C.I. I. Pigment yellow 12, C.I. I. Pigment blue 15: 1, C.I. I. Pigment Blue 15: 3 can be exemplified as a representative example.

  Typical examples of the release agent include low molecular weight polyethylene, low molecular weight polypropylene, Fischer-Tropsch wax, montan wax, carnauba wax, rice wax, and candelilla wax.

  A charge control agent may be added to the toner as necessary. Known charge control agents can be used. For example, an azo metal complex compound, a metal complex compound of salicylic acid, a resin type charge control agent containing a polar group, or the like can be used. When the toner is produced by a wet process, it is preferable to use a material that is difficult to dissolve in water from the viewpoint of controlling ionic strength and reducing wastewater contamination.

  Polystyrene fine particles, polymethyl methacrylate fine particles, polyvinylidene fluoride fine particles, and the like can be used as cleaning aids or transfer aids added to the toner.

  Silica, alumina, titania, calcium carbonate, magnesium carbonate, calcium phosphate, and the like can be used as the small-diameter inorganic fine particles added to the toner. You may use what carried out surface treatment to the inorganic fine particles as needed.

  The external additive can be mixed using a known mixer such as a V-type blender, a Henschel mixer, or a Redige mixer.

  When a developer having an autonomous toner concentration control mechanism described later is used, the toner in the present invention is a magnetic toner containing a magnetic material.

  Owing to the magnetism of the toner, it is possible to prevent the occurrence of soiling. This is because the toner is caught on the developer carrier by the magnetic bias, so that only sufficiently charged toner is developed, and insufficiently charged toner is not developed. This is thought to be possible.

Examples of the magnetic material used in the present invention include known magnetic materials such as metals such as iron, cobalt and nickel, and alloys thereof, Fe ₃ O ₄ , γ-Fe ₂ O ₃ , and metals such as cobalt-added iron oxide. Oxides, various ferrites such as MnZn ferrite and NiZn ferrite, magnetite, hematite and the like can be used. Further, the surface of these magnetic powders may be treated with a surface treatment agent such as a silane coupling agent or a titanate coupling agent, coated with an inorganic material such as a silicon compound or aluminum compound, or polymer coated. .

  The content of the magnetic powder is preferably in the range of 5 to 50% by weight, more preferably in the range of 10 to 40% by weight with respect to the whole toner particles. When the content of the magnetic powder is less than 5% by weight, the toner trapping force by the magnetic bias is not sufficient, so that the effect of preventing scumming cannot be obtained. On the other hand, if it exceeds 50% by weight, the magnetic bias is too large and the developability is extremely deteriorated, so that a sufficient image density cannot be obtained.

  Moreover, the volume average particle diameter of these magnetic powders is preferably about 0.05 to 0.35 μm from the viewpoint of dispersibility in the binder resin.

  Since the magnetic toner manufacturing method and the binder resin are the same as the toner manufacturing method and the toner binder resin described above, the description thereof is omitted here.

  In the present invention, a colorant other than magnetic powder may be used in combination for adjusting the coloring power. As the black colorant, black iron hydroxide, black titanium oxide, carbon black, or the like may be used in combination.

  In the present invention, a colorant other than magnetic powder may be used in combination for adjusting the coloring power. As the black colorant, black iron hydroxide, black titanium oxide, carbon black, or the like may be used in combination.

  Moreover, in order to adjust a color tone, you may contain coloring agents other than black. There is no restriction | limiting in particular as a coloring agent which can be used, A well-known coloring agent can be mentioned, According to the objective, it can select suitably. Examples of the colorant include DuPont Oil Red, Orient Oil Red, Rose Bengal, C.I. I. Pigment Red 5, 112, 123, 139, 144, 149, 166, 177, 178, 222, 48: 1, 48: 2, 48: 3, 53: 1, 57: 1, 81: 1, C.I. I. Pigment orange 31, 43, quinoline yellow, chrome yellow, C.I. I. Pigment Yellow 12, 14, 17, 93, 94, 97, 138, 174, 180, 188, ultramarine blue, aniline blue, calcoyl blue, methylene blue chloride, copper phthalocyanine, C.I. I. Pigment Blue 15, 60, 15: 1, 15: 2, 15: 3, C.I. I. Pigment Green 7 and malachite green oxalate can be used, and these can be used alone or in combination.

  The toner used in the present invention preferably contains a release agent to prevent the occurrence of offset.

  Specific examples of the release agent used in the present invention include low molecular weight polyolefins such as polyethylene, polypropylene, and polybutene, silicones that exhibit a softening point upon heating, oleic acid amide, erucic acid amide, ricinoleic acid amide, stearic acid amide Fatty acid amides such as carnauba wax, rice wax, candelilla wax, plant wax such as tree wax, jojoba oil, animal wax such as beeswax, montan wax, ozokerite, ceresin, paraffin wax, micro Minerals such as crystallin wax, microcrystalline wax, Fischer-Tropsch wax, petroleum-based waxes, and modified products thereof can be used.

  The toner used in the present invention may contain various substances as internal additives for the purpose of charge control. For example, high molecular acids such as fluorosurfactants, salicylic acid complexes, iron dyes such as iron complexes, chromium dyes such as chromium complexes, and copolymers containing maleic acid as a monomer component, quaternary Azine dyes such as ammonium salts and nigrosine may be added in the range of 0.1 to 10.0% by weight.

  The toner used in the present invention is preferably externally added with various inorganic or organic fine particles for the purpose of improving durability and powder fluidity.

  Examples of inorganic fine particles that can be used as an external additive include silica, aluminum oxide, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, silica sand, clay, mica, silica Apatite, diatomaceous earth, cerium chloride, bengara, chromium oxide, cerium oxide, antimony trioxide, magnesium oxide, magnesium carbonate, zirconium oxide, silicon carbide, silicon nitride, calcium carbonate, barium sulfate, and other metal oxides and ceramic particles Can be used.

  Moreover, it is preferable that these inorganic fine particles are hydrophobized. When the inorganic fine particles subjected to the hydrophobic treatment are used, the charge amount of the toner under high humidity can be improved, and as a result, the environmental stability of the chargeability of the toner can be improved.

  Hydrophobizing agents that can be used for the hydrophobizing treatment include coupling agents such as silane coupling agents, titanate coupling agents, aluminate coupling agents, zirconium coupling agents, silicone oils and polymers. Examples include coating treatment. These hydrophobizing agents can be used alone or in combination.

  In addition to the inorganic fine particles, organic fine particles can be externally added to the toner. Examples of the organic fine particles include vinyl polymers such as styrene polymers, (meth) acrylic polymers, and ethylene polymers, and various polymers such as ester, melamine, amide, and allyl phthalate. Fluorine polymers such as vinylidene fluoride and fine particles composed of higher alcohols such as unilin can be used, and those having a volume average primary particle size of 0.05 to 7.0 μm are preferably used. The organic fine particles are generally added for the purpose of improving cleaning properties and transferability.

  The external additive can be mixed using a known mixer such as a V-type blender, a Henschel mixer, or a Redige mixer.

[Developer]
The developer according to the present invention is a two-component developer composed of the above-described toner and carrier.

[Developing device used in image forming method]
A developing device used in the present invention includes a developer carrying member that includes a magnetic field generating unit therein and conveys and carries a magnetic two-component developer, and a toner containing unit that communicates with the developer containing unit and contains toner. And the toner density is autonomously controlled by regulating the amount of the two-component developer on the developer carrying member with a regulating member. At this time, the developer accommodating portion and the toner accommodating portion may be appropriately partitioned inside, and the shapes thereof are not limited.

  An example of an autonomous toner density control mechanism is shown in FIG.

  As shown in FIG. 1, a developer carrying body 10 that includes a magnetic field generating means that is in contact with the photosensitive drum 24 and fixed inside, and that rotates and carries a two-component developer containing toner and a magnetic carrier. A first developer accommodating portion 12 that accommodates the two-component developer adjacent to the developer bearing member 10, and is provided in communication with the developer bearing member 10 via the first developer accommodating portion 12. A second developer accommodating portion 14 that accommodates a developer having a toner concentration higher than that of the developer on the carrier so that the developer can be supplied, and a developer carrying portion via the first developer accommodating portion 12 and the second developer accommodating portion 14. A toner container 16 that is provided in communication with the body 10 and accommodates toner in the second developer container 14 so that toner can be supplied; and a developer that is adjacent to the developer carrier 10 with respect to the first developer container 12. When provided on the downstream side of the carrier 10 in the developer conveyance direction A developer retracting portion 20 that communicates with the first developer accommodating portion 12, and the developer carrying member 10 on the downstream side in the developer conveying direction with respect to the first developer accommodating portion 12 and the developer retracting portion 20, A part of the two-component developer carried and conveyed by the developer carrier 10 is blocked as an excess developer, and the excess developer is separated into the first developer accommodating portion 12 or the developer retracting portion 20 according to the toner concentration. The two-component developer separated into the developer retracting section 20 flows out into the second developer accommodating section 14.

  Next, the behavior of the two-component developer near the developer separating means 22 will be described. First, a case is assumed where the toner concentration of the two-component developer carried and conveyed by the developer carrier 10 is low. Since the two-component developer has a small amount of toner in the developer, the magnetic carrier density per unit volume is relatively large. That is, since the magnetic attraction force received by the two-component developer from the external magnetic field is increased, the two-component developer having a low toner concentration is reliably conveyed to the vicinity of the developer separating means (damping portion) 22. The two-component developer that has been reliably conveyed to the developer separating means 22 pushes out the staying developer staying in the vicinity of the developer separating means 22 by the damming force and magnetic restraining force of the developer separating means 22. The pushed-out staying developer becomes a falling developer and falls onto the partition part 26, passes through the developer retracting part 20, and then flows into the second developer accommodating part 14.

  At this time, when the two-component developer having a low toner concentration is led to the developer retracting portion 20 as described above, a space is created in the first developer accommodating portion 12 accordingly. As a result, the two-component developer that has been in the developer supply path from the developer supply port 18 to the first developer accommodating portion 12 is brought into the space by the conveying force of the stirring member and the weight of the two-component developer. The two-component developer in the vicinity of the developer supply port 18 is quickly drawn and flows. As a result, the developer supply port 18 receives the two-component developer having a high toner concentration from the second developer accommodating portion 14, and the two-component developer having the high toner concentration is supplied to the first developer accommodating portion 12. Promptly supplied. Further, a space for receiving toner from the toner container 16 is formed by the amount of developer supplied with a high toner concentration, and the toner T in the toner supply path is drawn in the developer stirring member, the weight of the toner T, and the toner stirring member. Is quickly supplied to the second developer accommodating portion 14.

  On the other hand, assuming that the toner concentration of the two-component developer carried and conveyed by the developer carrier 10 is high, this two-component developer has a relatively large unit volume because the amount of toner covering the surface of the magnetic carrier is large. The magnetic carrier density per hit is small. That is, since the magnetic attraction force received by the two-component developer from the external magnetic field is small, most of the two-component developer having a high toner concentration is upstream of the tip of the partition portion 26 with respect to the rotation direction of the developer carrier 10. It will fall at the position. As a result, the two-component developer does not reach the staying developer staying in the vicinity of the developer separating means 22 and does not fall on the partition portion 26. For this reason, the two-component developer does not fall on the partition portion 26 but falls at a position upstream of the tip end portion of the partition portion 26 with respect to the rotation direction of the developer carrier 10, and directly the first developer. Return to the storage unit 12. At this time, unlike the case where the toner concentration is low, no space is created in the first developer accommodating portion 12, and the two-component developer near the developer supply port 18 does not flow, so that it is blocked by the two-component developer. Thus, the two-component developer having a high toner concentration is not supplied from the second developer container 14. Similarly, no space for receiving the toner T from the toner storage unit 16 is formed in the second developer storage unit 14, so that the toner T is not supplied.

  As described above, the change in the fluidity and the change in the bulk of the two-component developer according to the toner concentration is utilized. Toner replenishment is performed for the two-component developer having a low toner concentration, and the toner concentration is reduced. The toner is not replenished for a high two-component developer.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention concretely, this invention is not limited by these. Note that the saturation magnetization was measured using the above-described apparatus and measurement conditions.

  The acid value and hydroxyl value of the binder resin used for the toner are those according to the titration method of JIS K 8006.

(Manufacture of carrier core material A)
In a 4-liter three-necked flask, 200 parts by weight of phenol, 260 parts by weight of 37% formalin, 1600 parts by weight of spherical magnetite having a volume average particle diameter of 0.3 μm, 31.2 parts by weight of 28% aqueous ammonia, 4 parts by weight of calcium fluoride Parts and 200 parts by weight of water were added with stirring, the temperature was raised to 85 ° C. at 1 ° C. per minute, and reaction and curing were performed at the same temperature for 3 hours to produce composite particles composed of spherical magnetite and a cured phenol resin. .

Next, the contents in the flask are cooled to room temperature, 2 liters of water is added, the supernatant is removed, and the composite particles remaining in the flask are washed with water, and the composite particles are separated and recovered by filtration. And left to dry. Furthermore, it dried at 60 degreeC under pressure reduction (5 mmHg or less), and obtained the carrier core material A of 35 micrometers of average particle diameters, true specific gravity 3.7g / cm < ³ >, and saturation magnetization 70emu / g. The content of the spherical magnetite in the carrier core material A was 90% by weight.

(Manufacture of carrier core B)
It was produced in the same manner as in the production example of carrier core A except that 1600 parts by weight of polyhedral magnetite fine particles having a volume average particle size of 0.3 μm were used as the ferromagnetic fine particles, and the average particle size was 35 μm and the true specific gravity was 3.6 g / A carrier core material B having a cm ³ saturation magnetization of 68 emu / g was obtained. The content of the polyhedral magnetite fine particles in the carrier core material B was 93% by weight.

(Manufacture of carrier core material C)
100 parts by weight of a polyester resin and 600 parts by weight of spherical magnetite fine particles having a volume average particle diameter of 0.3 μm are dry-mixed using a Henschel mixer, melt-kneaded with a three-roll mill, cooled and roughly ground with a hammer mill, and then with a jet mill. Finely pulverized and classified to obtain a carrier core material C having an average particle diameter of 35 μm, a true specific gravity of 3.5 g / cm ³ and a saturation magnetization of 65 emu / g. The content of spherical magnetite fine particles in the carrier core material C was 86% by weight.

(Manufacture of Carrier I)
Carrier core material A: 100 parts by weight (true specific gravity 3.7 g / cm ³ , volume average particle size 35 μm, saturation magnetization 70 emu / g)
Urethane ionomer resin aqueous dispersion “Hydran SP-510”: 4.9 parts by weight (manufactured by Dainippon Ink & Chemicals, Inc., solid content concentration 35%, tensile strength 58 MPa, tensile fracture elongation 280%)
Ion-exchanged water: 6.5 parts by weight Carbon black “R330R”: 0.3 parts by weight
(Cabot Corporation, volume average particle size 25 nm, DBP value 71 ml / 100 g, resistance 10 Ωcm or less)

The above components excluding the carrier core material A and glass beads (particle size 1 mm, the same amount as water) were put into a sand mill manufactured by Kansai Paint Co., Ltd., and stirred at a rotational speed of 1200 rpm for 30 minutes to prepare a coating resin layer forming solution. Next, the coating resin layer forming solution and the carrier core material A are put in a vacuum degassing type kneader and stirred for 10 minutes while maintaining a temperature of 60 ° C., and then the pressure is reduced to distill off the water, thereby removing the coating resin layer. To form Carrier I. The thickness of the coating resin layer was 1 μm. The carrier resistance under an electric field of 10 ^3.8 V / cm was 5 × 10 ⁹ Ωcm.

(Manufacture of Carrier II)
Carrier core material A: 100 parts by weight (true specific gravity 3.7 g / cm ³ , volume average particle size 35 μm, saturation magnetization 70 emu / g)
Polyester ionomer resin aqueous dispersion "Finetex ES-650":
5 parts by weight (manufactured by Dainippon Ink & Chemicals, Inc., solid content concentration 30%, tensile strength 65 MPa, tensile fracture elongation 170%)
Ion-exchanged water: 5 parts by weight Carbon black “R330R”: 0.3 parts by weight
(Cabot Corporation, volume average particle size 25 nm, DBP value 71 ml / 100 g, resistance 10 Ωcm or less)
Cross-linked melamine resin particles: 0.2 parts by weight (volume average particle size 0.3 μm)

The above components excluding the carrier core material A and glass beads (particle size 1 mm, the same amount as water) were put into a sand mill manufactured by Kansai Paint Co., Ltd., and stirred at a rotational speed of 1200 rpm for 30 minutes to prepare a coating resin layer forming solution. Next, the coating resin layer forming solution and the carrier core material A are put in a vacuum degassing type kneader and stirred for 10 minutes while maintaining a temperature of 60 ° C., and then the pressure is reduced to distill off the water, thereby removing the coating resin layer. To form Carrier II. The thickness of the coating resin layer was 1 μm. The carrier resistance under an electric field of 10 ^3.8 V / cm was 8 × 10 ⁹ Ωcm.

(Manufacture of carrier III)
Carrier core material B: 100 parts by weight (true specific gravity 3.6 g / cm ³ , volume average particle size 35 μm, saturation magnetization 68 emu / g)
Acrylic ionomer resin aqueous dispersion “Dick Fine EN-0440”:
5.7 parts by weight (Dainippon Ink Chemical Co., Ltd., solid content concentration 30%, tensile strength 32 MPa, tensile breaking elongation 390%)
Ion exchange water: 5.7 parts by weight Carbon black “R330R”: 0.3 parts by weight
(Cabot Corporation, volume average particle size 25 nm, DBP value 71 ml / 100 g, resistance 10 Ωcm or less)

The above components excluding the carrier core material B and glass beads (volume average particle diameter 1 mm, same amount as water) are put into a sand mill manufactured by Kansai Paint Co., Ltd. and stirred for 30 minutes at a rotation speed of 1200 rpm to prepare a solution for forming a coating resin layer. did. Next, the coating resin layer forming solution and the carrier core material B are put in a vacuum degassing type kneader and stirred for 10 minutes while maintaining a temperature of 60 ° C., and then the pressure is reduced to distill off the water, thereby removing the coating resin layer. To form carrier III. The thickness of the coating resin layer was 1 μm. The carrier resistance under an electric field of 10 ^3.8 V / cm was 2 × 10 ¹⁰ Ωcm.

(Carrier IV manufacturing)
Carrier core material C: 100 parts by weight (true specific gravity 3.5 g / cm ³ , volume average particle size 35 μm, saturation magnetization 65 emu / g)
Urethane ionomer resin aqueous dispersion “Hydran SP-510”: 4.9 parts by weight (manufactured by Dainippon Ink & Chemicals, Inc., solid content concentration 35%, tensile strength 58 MPa, tensile fracture elongation 280%)
Ion-exchanged water: 6.5 parts by weight Carbon black “R330R”: 0.3 parts by weight
(Cabot Corporation, volume average particle size 25 nm, DBP value 71 ml / 100 g, resistance 10 Ωcm or less)

The above components excluding the carrier core material C and glass beads (volume average particle diameter 1 mm, the same amount as water) are put into a sand mill manufactured by Kansai Paint Co., Ltd. and stirred for 30 minutes at a rotational speed of 1200 rpm to prepare a coating resin layer forming solution. did. Next, the coating resin layer forming solution and the carrier core material C are put into a vacuum degassing type kneader and stirred for 10 minutes while maintaining a temperature of 60 ° C., and then the pressure is reduced to distill off the water by depressurizing the coating resin layer. Formed to give Carrier IV. The thickness of the coating resin layer was 1 μm. The carrier resistance under an electric field of 10 ^3.8 V / cm was 7 × 10 ⁹ Ωcm.

(Manufacture of carrier V)
Carrier core material A: 100 parts by weight (true specific gravity 3.7 g / cm ³ , volume average particle size 35 μm, saturation magnetization 70 emu / g)
Urethane ionomer resin aqueous dispersion “Hydran HW-350”: 5.7 parts by weight (manufactured by Dainippon Ink & Chemicals, Inc., solid content concentration 30%, tensile strength 50 MPa, tensile breaking elongation 10%)
Ion exchange water: 5.7 parts by weight Carbon black “R330R”: 0.3 parts by weight
(Cabot Corporation, volume average particle size 25 nm, DBP value 71 ml / 100 g, resistance 10 Ωcm or less)

The above components excluding the carrier core material A and glass beads (volume average particle diameter 1 mm, same amount as water) are put into a sand mill manufactured by Kansai Paint Co., Ltd. and stirred for 30 minutes at a rotation speed of 1200 rpm to prepare a solution for forming a coating resin layer. did. Next, the coating resin layer forming solution and the carrier core material A are put in a vacuum degassing type kneader and stirred for 10 minutes while maintaining a temperature of 60 ° C., and then the pressure is reduced to distill off the water, thereby removing the coating resin layer. The carrier V was obtained. The thickness of the coating resin layer was 1 μm. Carrier resistance under an electric field of 10 ^3.8 V / cm was 3 × 10 ⁹ Ωcm.

(Manufacture of Carrier VI)
Carrier core material A: 100 parts by weight (true specific gravity 3.7 g / cm ³ , volume average particle size 35 μm, saturation magnetization 70 emu / g)
Urethane ionomer resin aqueous dispersion “Hydran APX-601”: 4.3 parts by weight (Dainippon Ink Chemical Co., Ltd., solid content concentration 40%, tensile strength 25 MPa, tensile breaking elongation 300%)
Ion-exchanged water: 7.2 parts by weight Carbon black “R330R”: 0.3 parts by weight
(Cabot Corporation, volume average particle size 25 nm, DBP value 71 ml / 100 g, resistance 10 Ωcm or less)

The above components excluding the carrier core material A and glass beads (particle size 1 mm, the same amount as water) were put into a sand mill manufactured by Kansai Paint Co., Ltd., and stirred at a rotational speed of 1200 rpm for 30 minutes to prepare a coating resin layer forming solution. Next, the coating resin layer forming solution and the carrier core material A are put in a vacuum degassing type kneader and stirred for 10 minutes while maintaining a temperature of 60 ° C., and then the pressure is reduced to distill off the water, thereby removing the coating resin layer. Formed to obtain Carrier VI. The thickness of the coating resin layer was 1 μm. The carrier resistance under an electric field of 10 ^3.8 V / cm was 4 × 10 ¹⁰ Ωcm.

(Manufacture of toner a)
Linear polyester resin: 89 parts by weight (Linear polyester obtained from terephthalic acid / bisphenol A ethylene oxide adduct / cyclohexanedimethanol; Tg = 62 ° C., Mn = 4000, Mw = 35000, acid value = 12 mgKOH / g, Hydroxyl value = 25 mgKOH / g)
Polypropylene wax (Mn = 3000): 5 parts by weight Carbon black (manufactured by Cabot, BPL): 6 parts by weight

The above components were kneaded with an extruder, pulverized with a jet mill, and then classified with an air classifier to obtain irregular toner particles having a volume average particle diameter D50 = 6.2 μm and a shape factor SF1 = 150. 1 part by weight of acicular rutile type titanium oxide (volume average particle diameter D50: 15 nm, powder resistance: 10 ¹⁵ Ωcm) surface-treated with n-decylsilane as an additive with respect to 100 parts by weight of the toner particles, Henschel After blending using a mixer, coarse particles were removed using a 45 μm mesh sieve to obtain toner a for developing an electrostatic latent image.

(Manufacture of toner b)
Preparation of resin fine particle dispersion (1) Styrene: 370 parts by weight n-butyl acrylate: 30 parts by weight Acrylic acid: 8 parts by weight Dodecanethiol: 24 parts by weight Carbon tetrabromide: 4 parts by weight

  6 parts by weight of a nonionic surfactant (manufactured by Sanyo Kasei Co., Ltd .: Nonipol 400) and 10 parts by weight of an anionic surfactant (manufactured by Daiichi Kogyo Seiyaku Co., Ltd .: Neogen SC) Dispersed in 550 parts by weight of ion-exchanged water, dispersed in a flask, emulsified, slowly mixed for 10 minutes, and then charged with 50 parts by weight of ion-exchanged water in which 4 parts by weight of ammonium persulfate had been dissolved. After the substitution, the inside of the flask was stirred and heated in an oil bath until the content reached 70 ° C., and emulsion polymerization was continued for 5 hours to obtain a resin fine particle dispersion (1). The resin particles of dispersion (1) had an average particle size of 155 nm, Tg of 59 ° C., and weight average molecular weight Mw of 12000.

Preparation of resin fine particle dispersion (2) Styrene: 280 parts by weight n-butyl acrylate: 120 parts by weight Acrylic acid: 8 parts by weight

  Using the above components, a resin fine particle dispersion (2) was obtained in the same manner as the resin fine particle dispersion (1). The resin particles of dispersion (2) had a volume average particle size of 105 nm, a Tg of 53 ° C., and a weight average molecular weight Mw of 550000.

Preparation of Colorant Dispersion (1) Carbon Black (Cabot: Mogul L): 50 parts by weight Nonionic surfactant (Sanyo Kasei: Nonipol 400): 5 parts by weight Ion exchange water: 200 parts by weight

  The above components are mixed and dissolved, and dispersed for 10 minutes using a homogenizer (manufactured by IKA: Ultra Turrax T50), and a colorant (carbon black) having a volume average particle size of 250 nm is added to the colorant dispersion (1). Was prepared.

Preparation of release agent dispersion (1) Paraffin wax: 50 parts by weight (manufactured by Nippon Seiwa Co., Ltd .: HNP0190, melting point 85 ° C.)
Cationic surfactant: 5 parts by weight (manufactured by Kao Corporation: SANISOL B50)
Ion exchange water: 200 parts by weight

  The above components are heated to 95 ° C. and dispersed using a homogenizer (manufactured by IKA: Ultra Turrax T50), and then dispersed with a pressure discharge type homogenizer to disperse a release agent having a volume average particle size of 550 nm. A release agent dispersion (1) was prepared.

Preparation of aggregated particles Resin fine particle dispersion (1): 120 parts by weight Resin fine particle dispersion (2): 80 parts by weight Colorant dispersion (1): 30 parts by weight Release agent dispersion (1): 40 parts by weight Cation Surfactant: 1.5 parts by weight (manufactured by Kao Corporation: Sanizol B50)

  The above components were mixed and dispersed in a round stainless steel flask using a homogenizer (manufactured by IKA: Ultra Tarrax T50), and then heated to 50 ° C. while stirring the inside of the flask in an oil bath for heating. By holding at 45 ° C. for 25 minutes, an aggregated particle dispersion was obtained. Observation with an optical microscope confirmed that aggregated particles having a volume average particle diameter of about 5.0 μm were formed.

Preparation of Adherent Particles 60 parts by weight of the resin fine particle dispersion (1) was gently added to the aggregated particle dispersion. And the temperature of the oil bath for heating was raised to 50 degreeC, and it hold | maintained for 40 minutes, and obtained the adhesion particle dispersion liquid. When observed with an optical microscope, it was confirmed that adhered particles having a volume average particle diameter of about 5.8 μm were formed.

Preparation of fused coalescent particles Add 3 parts by weight of an anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd .: Neogen SC) to the adhered particle dispersion, seal the stainless steel flask with a magnetic seal and continue stirring. While heating to 105 ° C., the mixture was held for 4 hours for fusion. Thereafter, the reaction product was cooled and filtered, washed thoroughly with ion-exchanged water, and dried to obtain toner particles. The volume average particle diameter D50 of the toner particles is 6.0 μm, and the shape factor SF1 is 110. 1 part by weight of acicular rutile titanium oxide (volume average particle diameter D50: 15 nm, powder resistance: 10 ¹⁵ Ωcm) surface-treated with decylsilane as an additive with respect to 100 parts by weight of the toner particles, and a Henschel mixer After blending, coarse particles were removed using a 45 μm mesh sieve to obtain electrostatic latent image developing toner b.

  9 parts by weight of the obtained toner for developing an electrostatic latent image and 100 parts by weight of each carrier are combined as shown in Table 1 and stirred for 20 minutes with a V blender at a rotation speed of 40 rpm, and sieved using a 177 μm mesh sieve. To obtain an electrostatic latent image developer.

(Evaluation methods)
These developers were used for comparative evaluation using an electrophotographic copying machine ("A-color 936" modified machine, manufactured by Fuji Xerox Co., Ltd.).

(1) Charging / image quality The developers of Examples 1 to 3 and Comparative Examples 1 to 3 are put in the developing device of the above-described electrophotographic copying machine, and are in a high temperature and high humidity environment (28 ° C., 85% RH) and a low temperature and low humidity environment. It was allowed to stand under (10 ° C., 15% RH) for a whole day and night. The above developing device was attached to the black toner position of the above copying machine, and 300,000 sheets of images were printed at a fixing temperature of 200 ° C. in each environment. The image quality evaluation and charging evaluation of the first and 300,000 image samples were performed, and the results are shown in Table 2. The image quality evaluation was based on the following criteria.

○: Good, △: Somewhat bad, ×: Bad

  In Examples 1 to 3, good image quality is maintained even after 300,000 sheets. In Comparative Example 1, the initial image quality is good, but after 300,000 sheets, a lot of the coating resin layer is peeled off. As a result, the fixing device is contaminated and the charge amount is reduced. A fog caused by a decrease in the amount occurred. In Comparative Examples 2 and 3, the initial image quality is good, but after 300,000 sheets, the surface of the coating resin layer is considerably contaminated by the toner component and the coating resin layer is worn. Occurred, and the image was lost due to contamination of the fixing device, and fogging due to a decrease in charge amount occurred.

(2) Transfer efficiency / image quality The developers of Examples 1 and 4 were put in the developing unit of the above-described electrophotographic copying machine, and left in an intermediate temperature / humidity environment (22 ° C., 55% RH) for 24 hours. The image quality was evaluated. The transfer efficiency is determined by measuring the amount of toner per unit area (TMA) transferred to the transfer belt and the amount of toner per unit area (DMA) not transferred on the photoconductor, and the transfer efficiency = (TMA) ÷ ( (TMA + DMA). For the image quality evaluation, several types of photographs and text image samples were taken and observed using a 100 × magnifier. The results are shown in Table 3. The image quality evaluation was based on the following criteria.

◎: Very good, ○: Good, △: Slightly bad, X: Bad

  In Example 4, transfer efficiency and image quality are improved by using toner having a shape factor of 110.

  Further, examples using a two-component developer containing a magnetic toner and a carrier will be described below.

  An example of manufacturing magnetic toner is shown below.

(Manufacture of toner c)
Polyester resin (Bisphenol A propylene oxide adduct / crosslinked polyester mainly composed of terephthalic acid, acid value = 10.0, Tg = 59.1 ° C.): 100 parts by weight magnetite (trade name: MTH009F, manufactured by Toda Kogyo): 44 Part by weight polypropylene wax (trade name: P200, manufactured by Mitsui Chemicals): 6 parts by weight

The above materials were powder-mixed with a Henschel mixer, and this was heat-kneaded with an extruder having a set temperature of 150 ° C. After cooling, coarsely pulverized, finely pulverized and classified to obtain a classified product having a volume average particle size of 7.5 μm, 5 μm or less: 22%. To 100 parts by weight of the obtained toner classified product, 0.1 part by weight of hydrophobic titanium oxide and 1.2 parts by weight of silicone oil-treated silica are externally added and mixed with a Henschel mixer, and then aggregates are removed to obtain a toner. c was obtained. Titanium oxide is an ilmenite ore, which is dissolved in sulfuric acid to separate iron powder. The obtained TiOSO ₄ is added with 5 parts of SiCl ₄ to 100 parts, hydrolyzed, and then washed with water. TiO (OH) ₂ containing Si component was obtained, and 8 parts of decyltrimethoxysilane was wet-treated with 100 parts of TiO (OH) ₂ without firing, dried, and pulverized with a jet mill. The obtained hydrophobic titanium oxide having a volume average particle diameter of 0.05 μm and silica is a silicone oil-treated silica (trade name: RY200, manufactured by Nippon Aerosil Co., Ltd.) having a volume average primary particle diameter of 0.012 μm.

(Manufacture of toner d)
Polyester resin (Bisphenol A propylene oxide adduct / crosslinked polyester mainly composed of terephthalic acid, acid value = 10.0 mg KOH / g, Tg = 59.1 ° C.): 100 parts by weight magnetite (trade name: MTH009F, manufactured by Toda Kogyo) : 36 parts by weight polypropylene wax (trade name: P200, manufactured by Mitsui Chemicals): 6 parts by weight carbon black (R330 manufactured by Cabot): 8 parts by weight

  The above materials were powder-mixed with a Henschel mixer, and this was heat-kneaded with an extruder having a set temperature of 150 ° C. After cooling, coarsely pulverized, finely pulverized, and classified to obtain a classified product of D50 = 7.5 μm, 5 μm or less: 22%. To 100 parts by weight of the obtained toner classified product, 0.1 part by weight of hydrophobic titanium oxide and 1.2 parts by weight of silicone oil-treated silica are externally added and mixed with a Henschel mixer, and then aggregates are removed to obtain a toner. d was obtained. The same titanium oxide and silica as in toner c were used.

  Carriers I to VI manufactured using carrier core materials A to C obtained by the same manufacturing method as described above were used.

(Developer adjustment)
In the combinations shown in Table 4, 20 parts by weight of toner was added to 100 parts by weight of the carrier, and the mixture was stirred and mixed with a ball mill for 5 minutes to obtain a magnetic two-component developer.

  As the developing device used in this example, the developing device shown in FIG. 1 was used. Two-component developer 60g was accommodated in the developer accommodating portion, and magnetic toner was accommodated in the toner accommodating portion. Furthermore, Fuji Xerox laser printer DocuPrint255 was modified to accommodate the developing device, and the following evaluation was performed. Evaluation was carried out in an environment of high temperature and high humidity (28 ° C., 85% RH).

1) Image Density 300,000 100% black solid images were output, and the image density was measured by a reflection densitometer X-Rite 404, and a difference ΔSAD between the image density of the tenth image and the image density of the 300,000 sheet was obtained.

<Evaluation criteria>
○: ΔSAD is less than 0.05.
Δ: ΔSAD 0.05-0.10
×: ΔSAD 0.10 or more

2) Evaluation of dirt
300,000 blank paper images were output, and the background stains of the tenth and 300,000 blank papers were evaluated according to the following evaluation criteria.

<Evaluation criteria>
◯: Compared with the white paper before printing, it is a level at which scumming cannot be detected visually.
(Triangle | delta): Although it can detect slightly visually compared with the white paper before printing, it is a level which is satisfactory practically.
X: Compared with the white paper before printing, the occurrence of background stains can be clearly detected with the naked eye, and this is a practically problematic level.

3) Image defects 300,000 100% black solid images were output, the defects on the tenth and 300,000 fixed images were visually confirmed, and evaluated according to the following evaluation criteria.

<Evaluation criteria>
○: Level at which no defect occurs on the image.
(Triangle | delta): Although the defect | deletion has generate | occur | produced slightly on the image, it is a level which is satisfactory practically.
X: Defects are observed on the image, and this is a practically problematic level.

The evaluation results are shown in Table 2.

  According to Table 5, in the developing device that autonomously controls the toner density, by using the developer of the present invention, it is possible to obtain an excellent image quality free from a decrease in image density, background contamination, image defects, etc. over a long period of time. it can. On the other hand, in Comparative Example 4, although the initial image quality is good, many peelings of the coating resin layer are observed after 300,000 sheets. This causes contamination of the fixing device and a decrease in the charge amount. And scumming occurred due to a decrease in charge. In Comparative Example 5 and Comparative Example 6, the initial image quality is good, but after 300,000 sheets, the surface of the coating resin layer is considerably contaminated by the toner component and the coating resin layer is worn. A decrease in the amount occurred, and the image was lost due to the contamination of the fixing device, and the background was stained due to a decrease in the charge amount.

  The electrostatic latent image developer carrier, electrostatic latent image developer and image forming method of the present invention are useful for applications such as electrophotography and electrostatic recording.

1 is a schematic diagram illustrating a configuration of a developing device used in an image forming method of the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Developer carrier, 12 1st developer accommodating part, 14 2nd developer accommodating part, 16 Toner accommodating part, 18 Developer supply port, 20 Developer retracting part, 22 Developer separating means, 24 Transfer roller.

Claims (4)

In the carrier for an electrostatic latent image developer having a coating resin layer on the core material,
The core material is formed by dispersing ferromagnetic fine particles in a phenol resin,
The coating resin layer is composed of one or more ionomer resins selected from polyurethane ionomer resins, polyester ionomer resins, and acrylic ionomer resins.
The carrier for an electrostatic latent image developer, wherein the ionomer resin has a tensile strength of 30 MPa to 200 MPa, and the ionomer resin has a tensile fracture elongation of 100% to 500%. In electrostatic latent image developer composed of toner and carrier,
The electrostatic latent image developer, wherein the toner has a shape factor SF1 of 100 or more and 140 or less, and the carrier is the carrier for an electrostatic latent image developer according to claim 1. A step of forming a latent image on the latent image carrier, a step of developing the latent image using a developer, a step of transferring the developed toner image to a transfer member, and heat fixing the toner image on the transfer member And an image forming method comprising:
An image forming method using the electrostatic latent image developer according to claim 2 as the developer. A developer carrying body having a magnetic field generating means therein and carrying and carrying a two-component developer containing toner and a magnetic carrier; and a toner containing portion communicating with the developer containing portion and containing the toner The amount of the two-component developer on the developer carrying member is regulated by a regulating member, and the toner intake of the two-component developer is autonomously controlled by changing the toner concentration of the two-component developer on the developer carrying member. An image forming method for forming an image using a developing device having a mechanism,
The toner is a magnetic toner containing at least a binder resin and a magnetic material,
The magnetic carrier is a carrier having a coating resin layer on a core material, and the core material is formed by dispersing ferromagnetic fine particles in a phenol resin, and the coating resin layer includes a polyurethane ionomer resin and a polyester ionomer. It consists of one or more ionomer resins selected from resins and acrylic ionomer resins, the ionomer resin has a tensile strength of 30 MPa to 200 MPa, and the ionomer resin has a tensile fracture elongation of 100% to 200%. There is provided an image forming method.

Images