JP2010223990A - Electrostatic charge image developing carrier, developer for electrostatic charge image development, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrostatic charge image developing carrier, wherein an image with a stable image density is formed for a long period of time, even for printing with low consumption. <P>SOLUTION: The electrostatic charge image developing carrier includes a carrier core material and a resin coating layer coating a surface of the carrier core material, and a sea-island structure wherein resin is phase-separated to a sea part and an island part is formed in the resin coating layer; and the sea part and the island part contain conductive particles, respectively; and a ratio between the sea part and the island part, which is confirmed by transmission electron microscopic observation, is within a range from 80:20 to 90:10, and an average dispersion diameter DirS of conductive particles in the sea part which is confirmed by transmission electron microscopic observation, is within a range from 30 to 60 nm; and the average dispersion diameter DirI of conductive particles in the island part is within a range from 100 to 210 nm. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an electrostatic charge image developing carrier, an electrostatic charge image developing developer, and an image forming apparatus.

  A method for visualizing image information through an electrostatic latent image (electrostatic image) such as electrophotography is currently used in various fields. In electrophotography, an electrostatic latent image formed on a photoreceptor by charging and exposure processes contains an electrostatic charge image developing toner (hereinafter sometimes referred to simply as “toner”). It is developed with an agent (hereinafter sometimes simply referred to as “developer”), and visualized through a transfer and fixing process. As a developer used for development, a two-component developer including a toner and a carrier for developing an electrostatic image (hereinafter sometimes simply referred to as “carrier”) and a toner used alone such as a magnetic toner are used. There are component developers, but the two-component developer has characteristics such as good controllability because the carrier shares functions such as stirring, transport and charging of the developer and is separated as a developer. Is currently widely used.

  Carriers are generally classified into resin-coated carriers having a resin coating layer on the surface of magnetic particles (core particles) and uncoated carriers having no coating layer on the surface. Developers using resin-coated carriers are generally charged. It has excellent controllability and is relatively easy to improve environmental dependency and stability over time. As a developing method, a cascade method has been used in the past, but at present, a magnetic brush method using a magnetic roll as a developer carrier is mainly used.

  Patent Document 1 describes that in order to prevent a decrease in image density, carbon black is added to the surface of magnetic particles coated with a silicone resin or the like to reduce resistance.

  Patent Document 2 describes a carrier in which a coating layer is formed of two types of incompatible resins and conductive powder is dispersed in one resin in order to improve charge maintenance.

Patent Document 3 discloses a magnetic carrier obtained by coating the surface of a magnetic carrier core particle having a binder resin, magnetic particles, and a high dielectric compound with a coating material for the purpose of stabilizing image density at the time of printing with low consumption. In the particles, the magnetic carrier particles are electrophotographic carriers in which the volume resistivity at 5 × 10 ⁵ V / m is 1 × 10 ⁹ to 1 × 10 ¹⁶ Ωcm, and the relative dielectric constant ε of the high dielectric compound is 80 or more. Are listed.

Japanese Patent Laid-Open No. 6-148952 JP-A-9-26675 JP 2007-102052 A

  An object of the present invention is to provide an electrostatic charge image developing carrier capable of forming an image having a stable image density over a long period of time even in low-consumption printing.

  The present invention includes a carrier core material and a resin coating layer that covers a surface of the carrier core material, and in the resin coating layer, a sea island structure is formed in which a resin is phase-separated into a sea part and an island part, and the sea part is formed. And each of the islands contains conductive particles, and the ratio of the sea part to the island part confirmed by observation with a transmission electron microscope is in the range of 80:20 or more and 90:10 or less, and observation with a transmission electron microscope. In which the average dispersion diameter DirS of the conductive particles in the sea portion is in the range of 30 nm to 60 nm and the average dispersion diameter DirI of the conductive particles in the island portion is in the range of 100 nm to 210 nm. It is a carrier for image development.

  The present invention also provides an electrostatic charge image developing developer comprising the electrostatic charge image developing carrier and the electrostatic charge image developing toner.

  The present invention also provides an image carrier, latent image forming means for forming an electrostatic latent image on the surface of the image carrier, and developing the electrostatic latent image using a developer to form a toner image. An image forming apparatus comprising: a developing unit; and a transfer unit that transfers the developed toner image to a transfer target, wherein the developer is the developer for developing an electrostatic image.

  According to the first aspect of the present invention, when the resin coating layer covering the surface of the carrier core material does not have this configuration, when used in an image forming apparatus, even in low-consumption printing. It is possible to provide a carrier for developing an electrostatic image on which an image having a stable image density can be formed over a long period of time.

  According to the second aspect of the present invention, when used in an image forming apparatus, compared with the case where a carrier not having this configuration is used, a stable image density can be obtained over a long period even when printing with low consumption. A developer for developing an electrostatic image on which an image is formed can be provided.

  According to the third aspect of the present invention, an image forming apparatus capable of forming an image having a stable image density over a long period of time even in a low-consumption printing as compared with the case where a developer not having this configuration is used. Can be provided.

1 is a schematic configuration diagram illustrating an example of an image forming apparatus according to an embodiment of the present invention.

  Embodiments of the present invention will be described below. This embodiment is an example for carrying out the present invention, and the present invention is not limited to this embodiment.

<Carrier for developing electrostatic image>
In a magnetic brush method using a two-component developer, etc., if low-consumption printing (low area coverage printing) with low toner consumption is continued, the toner stays in the developing machine for a long time due to low toner consumption. Stirring increases the charge amount of the toner, and as a result, the image density may decrease. On the other hand, it is conceivable to reduce the resistance by adding carbon black to the surface of magnetic particles coated with a silicone resin or the like, but in this case, the distribution of micro resistance on the carrier surface becomes wide, so that the toner In some cases, the charge distribution becomes wider and stable image density cannot be maintained. Therefore, in order to stabilize the image density at the time of printing with low consumption, magnetic carrier particles are produced by coating the surface of a magnetic carrier core particle having a binder resin, magnetic particles, and a high dielectric compound with a coating material. It is conceivable that the volume resistivity is 1 × 10 ⁹ to 1 × 10 ¹⁶ Ωcm and the relative dielectric constant ε of the high dielectric compound is 80 or more, but the stability of image density when printing with low consumption is continued. There is still room for improvement.

  The present inventors have a carrier core material and a resin coating layer containing conductive particles. In the resin coating layer, a sea island structure is formed in which a resin, for example, at least two kinds of resins are phase-separated into a sea portion and an island portion. However, the ratio of the sea part to the island part is within the specified range, the average dispersion diameter of the conductive particles in the sea part is smaller than the average dispersion diameter of the conductive particles in the island part, and both are within the specified range. It has been found that by using the carrier structure, an image with a stable image density can be formed over a long period of time even when printing with low consumption.

  The carrier for developing an electrostatic image according to the embodiment of the present invention includes a carrier core material and a resin coating layer that covers the surface of the carrier core material. The resin coating layer forms a sea-island structure in which the resin is phase-separated into a sea part and an island part, and each of the sea part and the island part contains conductive particles. Further, the ratio of the sea part and the island part confirmed in the transmission electron microscope observation is in the range of 80:20 or more and 90:10 or less, and the average dispersion diameter of the conductive particles in the sea part confirmed in the transmission electron microscope observation DirS is in the range of 30 nm to 60 nm, and the average dispersion diameter DirI of the conductive particles in the island is in the range of 100 nm to 210 nm.

  With this configuration, the sea part on the surface of the carrier, that is, a high resistance part, and the island part, that is, a low resistance part whose micro resistance value is moderately lower than that of the sea part, are obtained without substantially reducing the macro resistance value of the entire carrier. The charge of the toner frictionally charged at the high resistance portion of the carrier surface leaks moderately when it contacts the low resistance portion, and the excessive increase in the charge of the toner is suppressed, resulting in low consumption. In this printing, an image having a stable image density can be formed over a long period of time.

  It is confirmed by observation of the resin coating layer portion of the cross section of the carrier using a transmission electron microscope that the sea-island structure is formed in the resin coating layer and the sea portion and the island portion contain conductive particles. Observation of the resin coating layer portion of the cross section of the carrier was carried out by cutting carrier particles with a diamond knife or the like and using a transmission electron microscope at a magnification of 10,000 times.

  The ratio of the sea part and the island part confirmed by transmission electron microscope observation is in the range of 80:20 to 90:10, and preferably in the range of 83:17 to 88:12. If the ratio of the sea portion is smaller than 80, the low resistance portion of the carrier surface is excessively increased, the macro resistance value of the carrier is lowered, the toner charge amount is lowered, and the image is fogged. If the ratio of the sea part exceeds 90, the chance that the toner surface comes into contact with the low resistance part of the carrier surface is reduced, the increase in the toner charge amount is not suppressed, and the image density is lowered.

  The ratio of the sea part and the island part of the resin coating layer of the carrier is obtained by calculating the respective areas of the sea part and the island part confirmed by the observation image by the transmission electron microscope, and calculating the ratio. The ratio of the sea part to the island part is an average value of the areas of the sea part and the island part of 100 carriers selected at random.

  The average dispersion diameter DirS of the conductive particles in the sea portion confirmed by observation with a transmission electron microscope is in the range of 30 nm to 60 nm, and preferably in the range of 35 nm to 55 nm. When DirS is smaller than 30 nm, a sudden increase in the toner charge amount is not suppressed and the image density is lowered. If DirS is larger than 60 nm, the effect of suppressing the increase in the toner charge amount functions too much, the toner charge amount decreases, and the image is fogged.

  The average dispersion diameter DirI of the conductive particles in the island portion confirmed by transmission electron microscope observation is in the range of 100 nm to 210 nm, and preferably in the range of 120 nm to 180 nm. When DirI is smaller than 100 nm, the effect of suppressing the increase in the toner charge amount when the island portion of the carrier surface and the toner surface come into contact with each other becomes insufficient, and the image density is lowered. When DirI is larger than 210 nm, the resistance value of the island portion on the carrier surface becomes non-uniform, and unevenness occurs in the suppression of increase in the toner charge amount due to charge leakage when the island portion and the toner surface are in contact with each other. Will occur.

  The average dispersion diameter of the conductive particles in the sea part and the island part of the resin coating layer of the carrier is 100 conductive particles selected at random in each of the sea part and the island part confirmed by the observation image by the transmission electron microscope. The dispersion diameter of the aggregate is measured and taken as the average value.

[Carrier core]
As the core particles (carrier core material), any conventionally known particles can be used, and ferrite and magnetite are particularly preferably selected. For example, iron powder is known as another core particle. In the case of iron powder, since the specific gravity is large and the toner is likely to be deteriorated, ferrite and magnetite are more stable. An example of ferrite is generally represented by the following formula.
(MO) _X (Fe ₂ O ₃ ) _Y
(In the formula, M contains at least one selected from Cu, Zn, Fe, Mg, Mn, Ca, Li, Ti, Ni, Sn, Sr, Al, Ba, Co, Mo, etc. X, Y represents a mass mol ratio and satisfies the condition X + Y = 100.)

The M is a ferrite particle in which the content of one or more of Li, Mg, Ca, Mn, Sr, and Sn is other than 1% by mass. By adding Cu, Zn and Ni elements, the resistance tends to be low, and charge leakage tends to occur. In addition, the resin tends to be difficult to coat, and the environmental dependency tends to deteriorate. Furthermore, since it is a heavy metal, the stress given to a carrier becomes strong and may have a bad influence with respect to preservability. In recent years, from the viewpoint of safety, an element containing Mn element or Mg element has been widely used. Ferrite core material is preferable. As raw material for core particles, Fe ₂ O ₃ is an essential component, and as magnetic particles used, ferromagnetic iron oxide particles such as magnetite and maghemite, metals other than iron (Mn, Ni, Zn, Mg, Cu, etc.) containing one or more kinds of spinel ferrite particle powder, barium ferrite magnetplumbite type ferrite particle powder, iron or iron alloy particle powder having an oxide film on the surface, etc. Can be mentioned.

  Specific examples of core particles include iron oxides such as magnetite, γ-iron oxide, Mn—Zn ferrite, Ni—Zn ferrite, Mn—Mg ferrite, Li ferrite, and Cu—Zn ferrite. Etc. Among these, inexpensive magnetite is more preferably used.

  The core particles may be resin-dispersed core particles in which the magnetic particles (magnetic material) are dispersed in a binder resin.

  As the binder resin, a phenol resin, a melamine resin, an epoxy resin, a urethane resin, a polyester resin, a silicone resin, or the like is used, but a phenol resin is preferably included. By using a phenol-based resin, adhesion with the coating resin is improved, and long-term stability is further improved.

  At this time, a desired surface state can be obtained by making the volume average particle size of the magnetic material in the binder resin uniform within a range of 5 μm or more and 10 μm or less, increasing the magnetic material ratio, and appropriately exposing.

[Coating resin]
The coating resin used for the resin coating layer is not particularly limited as long as it is a combination that forms a sea-island structure, and a known resin may be used. Specific examples include styrenes such as styrene, chlorostyrene and methylstyrene; methyl methacrylate, methyl acrylate, propyl acrylate, lauryl acrylate, cyclohexyl methacrylate, methacrylic acid, acrylic acid, butyl methacrylate, butyl acrylate, 2-ethylhexyl acrylate, Α-methylene aliphatic monocarboxylic acids such as ethyl methacrylate; nitrogen-containing acrylics such as dimethylaminoethyl methacrylate; nitriles such as acrylonitrile and methacrylonitrile; vinylpyridines such as 2-vinylpyridine and 4-vinylpyridine; Vinyl ketones: olefins such as ethylene, propylene and butadiene; main chain nitrogen-containing resins such as polyamide, polyimide and melamine; methyl It may be used homopolymers such as, or a copolymer; silicon, silicon such as methyl phenyl silicone; bisphenols, polyesters containing glycol. Particularly preferred are methyl methacrylate, methyl acrylate, propyl acrylate, cyclohexyl acrylate and the like.

  Of these resins, a combination that forms a sea-island structure may be selected. For example, a combination of resins having the same structure and different molecular weights (for example, combinations of methyl methacrylate copolymers having different molecular weights), although the molecular weights are close. A combination of resins having different structures (for example, a combination of a methyl methacrylate copolymer and a butyrate copolymer), a combination of resins having different structures and different molecular weights, and the like may be appropriately selected.

  In order to form the sea-island structure, for example, two types of coating resins having a difference in weight average molecular weight of about 60,000 or more and 100,000 or less may be used. If the difference in weight average molecular weight is less than 60,000, the sea-island structure may not be formed, and if it exceeds 100,000, the average dispersion diameters DirS and DirI of the conductive particles in the sea and islands may not be in the essential range. .

[Conductive particles]
The conductive particles used for the resin coating layer are not particularly limited as long as the particles exhibit conductivity, but specifically, metal oxides such as carbon black, various metal powders, titanium oxide, tin oxide, magnetite, and ferrite. Such as things. Carbon black is particularly preferred because high conductivity can be imparted with a small amount of addition, and the degree of conductivity can be easily controlled by the blending amount.

  The addition amount of the conductive particles is preferably less than 20% by volume of the resin coating layer. When 20 volume% or more is added, it is difficult to control the dispersion of the powder in the resin coating layer, and it may be difficult to control the electric resistance.

[Others]
The resin coating layer may contain a negative charge control agent. Negative charge control agents include trimethylethane dyes, metal complexes of salicylic acid, metal complexes of benzylic acid, copper phthalocyanine, perylene, quinacridone, azo pigments, metal complex azo dyes, azochrome complexes, etc. Examples include dyes, calixarene type phenolic condensates, cyclic polysaccharides, resins containing at least one of carboxyl groups and sulfonyl groups.

  The content of the negative charge control agent is preferably in the range of 0.001% by mass to 1.0% by mass with respect to the mass of the core particles, and is 0.01% by mass to 0.8% by mass. More preferably, it is the range. When the content of the negative charge control agent is less than 0.001% by mass with respect to the mass of the core particles, there is a case where there is no effect on the toner charge rising property. It may inhibit the charging ability.

  The resin coating layer of the carrier may contain a wax. Waxes are usually hydrophobic, are relatively soft at room temperature, and have low film strength. This originates from the molecular structure of the wax, but due to this characteristic, when wax is present in the resin coating layer, toner components such as external additives added to the toner surface or toner bulk components are added to the carrier surface. Hard to adhere. Even if it adheres, the surface of the carrier is renewed by peeling off the wax at the adhesion level at the molecular level, and the carrier surface is not easily contaminated.

  The wax is not particularly limited, and examples thereof include paraffin wax and derivatives thereof, montan wax and derivatives thereof, microcrystalline wax and derivatives thereof, Fischer-Tropsch wax and derivatives thereof, polyolefin wax and derivatives thereof, and the like. Derivatives include oxides, polymers with vinyl monomers, and graft modified products. In addition, alcohol, fatty acid, plant wax, animal wax, mineral wax, ester wax, acid amide, and the like may be used. Moreover, you may use another well-known thing. The melting point of the wax is preferably 60 ° C. or higher and 200 ° C. or lower. More preferably, the melting point of the wax is 80 ° C. or higher and 150 ° C. or lower. If it is less than 60 degreeC, the fluidity | liquidity as a carrier may deteriorate.

  Moreover, in order to improve the adhesiveness between the core particle surface and the coating resin, the core particles may be subjected to a coupling treatment. Examples of coupling agents include silane coupling agents, silicone oils, titanate coupling agents, and aluminum coupling agents. These may be used individually by 1 type and may use 2 or more types together. Of these, silane coupling agents are preferred.

  As the silane coupling agent, any type of chlorosilane, alkoxysilane, silazane, and special silylating agent may be used. Specifically, methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, phenyltrichlorosilane, diphenyldichlorosilane, tetramethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, tetraethoxysilane, Methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, diphenyldiethoxysilane, isobutyltrimethoxysilane, decyltrimethoxysilane, hexamethyldisilazane, N, O- (bistrimethylsilyl) acetamide, N, N-bis (Trimethylsilyl) urea, tert-butyldimethylchlorosilane, vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxy Silane, γ-methacryloxypropyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-mercapto Examples include propyltrimethoxysilane, γ-chloropropyltrimethoxysilane, and γ-aminopropyltriethoxysilane.

  Examples of titanate coupling agents include “Plenact KR TTS”, “Plenact KR 46B”, “Plenact KR 55”, “Plenact KR 41B”, “Plenact KR 38S”, “Plenact KR 138S”, “Prenact K”. ”,“ Plenact 338X ”,“ Plenact KR 44 ”,“ Plenact KR 9SA ”,“ Plenact KR ET ”(all of which are manufactured by Ajinomoto Fine Techno Co., Ltd.) and the like. Examples include acetoacetate aluminum diisopropylate (“Plenact AL-M” manufactured by Ajinomoto Fine Techno Co., Ltd.).

  The thickness of the resin coating layer is preferably in the range of 0.1 μm to 5 μm, and more preferably in the range of 0.2 μm to 3 μm. If the thickness of the resin coating layer is smaller than 0.1 μm, it may be difficult to form a resin coating layer that is as uniform and flat as possible on the surface of the core particles. On the other hand, if the thickness is larger than 5 μm, it may be difficult to obtain a carrier that is as uniform as possible by aggregating the carriers.

<Carrier manufacturing method>
The method for producing the carrier according to the present embodiment is not particularly limited as long as it can form the carrier having the above-described configuration, but the following production method is preferable.

  As described above, the coating resin used in the following production method preferably has a weight average molecular weight difference of about 60,000 to 100,000.

  The resin-coated carrier is, for example, a spray in which a solution in which two types of coating resins are dissolved is stirred and dispersed using a disperser such as UltraTurrax T50, and the resin coating layer forming solution is sprayed on the surface of the carrier core material. The resin coating layer forming solution and the carrier core material may be mixed in a kneader coater and then the solvent removed, and the like.

  In such a carrier manufacturing method, for example, the ratio of the sea part to the island part may be adjusted by changing the mixing ratio of two types of coating resins.

  For example, when a combination of two types of coating resins that undergo phase separation is selected and the difference in weight average molecular weight of the coating resins is, for example, about 60,000 or more and 100,000 or less, in a resin phase having a small weight average molecular weight, Since the viscosity of the resin is low, it is difficult to apply a shearing force to the conductive particles during dispersion, and the dispersion diameter of the conductive particles tends to increase. On the other hand, in a resin phase having a large weight average molecular weight, since the viscosity of the resin is high, a shearing force is easily applied to the conductive particles during dispersion, and the dispersion diameter of the conductive particles tends to be small. Therefore, for example, the structure, molecular weight, etc. of two types of coating resins, that is, the viscosity of the resin is appropriately selected, and the processing temperature, stirring speed, stirring time when dispersing the solution containing the two types of coating resins and conductive particles are dispersed. The dispersion diameter of the conductive particles in each phase may be controlled by adjusting the above.

  By applying to the surface of the carrier core material while keeping the phase separation state of the resin coating layer forming solution in which the dispersion diameter of the conductive particles and the like are controlled as described above by the spray method or the kneader coater method as much as possible. A resin coating layer having a sea-island structure and having a dispersion diameter of conductive particles in the sea part and the island part within the above range is formed.

  In addition to the two types of coating resins, the resin coating layer forming solution may appropriately include conductive particles, a charge control agent used as necessary, and the like. The solvent for dissolving the two types of coating resin is not particularly limited as long as it dissolves the coating resin. For example, aromatic hydrocarbons such as xylene and toluene, and ketones such as acetone and methyl ethyl ketone , Ethers such as tetrahydrofuran and dioxane, and halides such as chloroform and carbon tetrachloride may be used.

<Toner for electrostatic image development>
The toner is not particularly limited, and a known toner containing a binder resin and a colorant as main components and containing a release agent or the like as necessary may be used. The toner may be produced by a dry production method such as a kneading and pulverization method, or may be produced by a wet production method such as an emulsion polymerization aggregation method, a dissolution suspension method, or a suspension polymerization method. . A toner produced by a wet production method such as an emulsion polymerization agglomeration method is preferred from the standpoint that the surface exposure of the colorant and the release agent is small and the stability of the image is good.

  Such toner has a relatively spherical particle shape, a narrow particle size distribution, a relatively uniform toner surface, high chargeability, and a narrow and favorable charge distribution. Since this toner has a narrow particle size distribution, the occurrence of fogging is small.

  As the binder resin for the toner, styrenes such as styrene and chlorostyrene; monoolefins such as ethylene, propylene, butylene, and isobutylene; vinyl acetate, vinyl propionate, vinyl benzoate, vinyl butyrate, methyl acrylate, acrylic acid Esters of α-methylene aliphatic monocarboxylic acids such as ethyl, butyl acrylate, dodecyl acrylate, octyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, dodecyl methacrylate; vinyl methyl ether, Homopolymers or copolymers of vinyl ethers such as vinyl ethyl ether and vinyl butyl ether; vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, vinyl isopropenyl ketone, and particularly representative binding As fat, polystyrene, styrene-alkyl acrylate copolymer, styrene-alkyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyethylene, polypropylene Etc. Furthermore, polyester, polyurethane, epoxy resin, silicone resin, polyamide, modified rosin, paraffin waxes and the like can be mentioned.

  Examples of the colorant include carbon black, chrome yellow, hansa yellow, benzidine yellow, selenium yellow, quinoline yellow, permanent orange GTR, pyrazolone orange, vulcan orange, watch young red, permanent red, brillianthamine 3B, and brillianthamine. 6B, DuPont Oil Red, Pyrazolone Red, Resol Red, Rhodamine B Lake, Lake Red C, Rose Bengal, Aniline Blue, Ultramarine Blue, Calco Oil Blue, Methylene Blue Chloride, Phthalocyanine Blue, Phthalocyanine Green, Malachite Green Oxalate, etc. Or acridine, xanthene, azo, benzoquinone, azine, anthraquinone, thio Various dyes such as Ndico, Dioxazine, Thiazine, Azomethine, Indico, Thioindico, Phthalocyanine, Aniline Black, Polymethine, Triphenylmethane, Diphenylmethane, Thiazine, Thiazole, and Xanthene Or in combination of two or more.

  In the toner according to the exemplary embodiment, the content of the colorant is preferably in the range of 1 part by mass to 30 parts by mass with respect to 100 parts by mass of the binder resin. It is also effective to use a surface-treated colorant or a pigment dispersant as necessary. By appropriately selecting the type of the colorant, yellow toner, magenta toner, cyan toner, black toner and the like can be obtained.

  Examples of mold release agents include low molecular weight polyolefins such as polyethylene, polypropylene and polybutene; silicones having a softening point upon heating; fatty acid amides such as oleic acid amide, erucic acid amide, ricinoleic acid amide and stearic acid amide; Plant waxes such as ester wax, carnauba wax, rice wax, candelilla wax, tree wax, jojoba oil, etc .; animal waxes such as beeswax; montan wax, ozokerite, ceresin, paraffin wax, microcrystalline wax, fisher Mineral waxes such as Tropsch wax, petroleum waxes, and modified products thereof may be used. The addition amount of the release agent may be added in the range of 50% by mass or less with respect to the toner.

  In addition, as an internal additive, a magnetic material such as a metal such as ferrite, magnetite, reduced iron, cobalt, nickel, or manganese, an alloy thereof, or a compound containing the metal may be used. As the charge control agent, a quaternary ammonium salt, a nigrosine compound, a dye composed of a complex such as aluminum, iron, or chromium, or various commonly used charge control agents such as a triphenylmethane pigment may be used. A charge control agent that is difficult to dissolve in water is suitable for controlling the ionic strength that affects the stability during aggregation and fusion integration and reducing wastewater contamination.

  Examples of inorganic particles to be wet-added include silica, alumina, titania, calcium carbonate, magnesium carbonate, and tricalcium phosphate, all of which are usually used as external additives on the toner surface, such as ionic surfactants and What is necessary is just to disperse | distribute with a polymeric acid and a polymeric base, and to add wet.

  Surfactants used for emulsion polymerization, seed polymerization, pigment dispersion, resin particles, release agent dispersion, aggregation, or stabilization in the toner manufacturing process by a wet manufacturing method include sulfate ester salts, sulfonate salts, phosphorus Examples thereof include anionic surfactants such as acid esters and soaps, and cationic surfactants such as amine salts and quaternary ammonium salts, and also polyethylene glycols, alkylphenol ethylene oxide adducts, polyhydric alcohols. It is also effective to use a nonionic surfactant such as a system together.

  Moreover, what is necessary is just to use well-known external additives, such as an inorganic particle and an organic particle, as an external additive (external additive) used in this embodiment. Among these, inorganic particles such as silica, titania, alumina, cerium oxide, strontium titanate, calcium carbonate, magnesium carbonate and calcium phosphate, metal soap such as zinc stearate, fluorine-containing resin particles, silica-containing resin particles and nitrogen Organic resin particles such as containing resin particles are preferred. Moreover, you may surface-treat on the surface of an external additive according to the objective. Examples of the surface treatment agent include a silane compound, a silane coupling agent, and a silicone oil for performing a hydrophobic treatment.

  The volume average particle size of the toner according to the exemplary embodiment is preferably in the range of 4 μm to 8 μm, and more preferably in the range of 5 μm to 7 μm. If the volume average particle diameter of the toner is less than 4 μm, the amount of fine powder increases, so that toner fog and poor cleaning are likely to occur.

  In addition, the volume average particle size distribution index GSDv of the toner according to the exemplary embodiment is preferably in the range of 1.0 to 1.3, more preferably in the range of 1.1 to 1.3. More preferably, it is in the range of 1.15 or more and 1.24 or less. When the GSDv exceeds 1.3, the presence of coarse particles and fine powder particles increases, so that the toner is agglomerated and tends to cause charging failure and transfer failure. Moreover, when GSDv is less than 1.1, it will be quite difficult to manufacture.

The volume average particle size D50v and the volume average particle size distribution index GSDv are measured using a Coulter-Multisizer-II type (manufactured by Beckman-Coulter) with an aperture diameter of 100 μm. At this time, the measurement is performed after the toner is dispersed in an electrolyte aqueous solution (Isoton II aqueous solution) and dispersed by ultrasonic waves for 30 seconds or more. For the particle size range (channel) divided based on the measured particle size distribution of the toner, a cumulative distribution is drawn from the small diameter side for each of the volume and number, and the particle size that becomes 16% is the volume D16v and the cumulative is 50%. The particle diameter to be defined is defined as volume D50v, and the particle diameter to be accumulated 84% is defined as volume D84v. At this time, D50v represents the volume average particle diameter, volume average particle size distribution index (GSDv) is determined as ^1/2 (D84v / ^D16v).

  In addition, the toner shape factor SF1 represented by the following formula of the toner for developing an electrostatic charge image according to the exemplary embodiment is preferably in the range of 110 to 140, and more preferably in the range of 115 to 135. More preferably, it is in the range of 120 to 130. If the toner shape factor SF1 is less than 110, the toner particles are close to a spherical shape, which may cause a cleaning failure after transfer. On the other hand, when the toner shape factor SF1 exceeds 140, not only the transfer efficiency and the image quality are deteriorated, but also the shape range of the toner particles obtained by a low-temperature manufacturing method may be exceeded.

SF1 = (ML ² / A) × (π / 4) × 100
(In the above formula, ML represents the maximum length (μm) of the toner, and A represents the projected area (μm ² ) of the toner.)

  The toner shape factor SF1 is measured as follows using a Luzex image analyzer (manufactured by Nireco Corporation, FT). First, an optical microscope image of the toner spread on the slide glass is taken into a Luzex image analyzer through a video camera, and the maximum length (ML) and the projected area (A) of 50 toners are measured. SF1 is calculated, and an average of these values is obtained as the toner shape factor SF1.

<Developer for developing electrostatic image>
The developer for developing an electrostatic charge image according to the exemplary embodiment includes a toner and a carrier, and the carrier is the carrier for developing an electrostatic charge image. That is, the developer for developing an electrostatic charge image according to the exemplary embodiment is a two-component developer including a toner and a carrier.

  The ratio of the toner when preparing the developer by mixing the toner and the carrier is in the range of 1% by mass to 15% by mass, preferably 3% by mass to 12% by mass of the entire developer.

If the toner ratio is less than 1% by mass, it may be difficult to obtain a sufficient image density, or a solid image may not be uniform. On the other hand, if the amount exceeds 15% by mass, the toner coverage on the carrier surface exceeds 100% and the charge amount decreases (when the absolute value of the average charge amount is less than 15 μC / g). Fog) A high-quality color image may not be obtained. For example, if the amount exceeds 15% by mass, the toner coverage on the carrier surface approaches 100%, so that the resistance value as a developer increases extremely, and is 1 × 10 ⁵ Ω · cm or more and 1 × 10 ⁸ Ω · cm or less. In such a case, it may be difficult to obtain a good and high-quality color image such as blurring of an image edge portion.

  However, in a low humidity environment, if the toner ratio is less than 1% by mass, a high charge amount (the absolute value of the average charge amount exceeds 25 μC / g) tends to occur, and it may be difficult to obtain a sufficient image density. Therefore, it is preferable to select the toner ratio so that the absolute value of the charging property is in the range of 15 μC / g or more and 50 μC / g or less according to the environment.

<Image forming apparatus>
The image forming apparatus according to the present embodiment includes an image carrier, latent image forming means for forming an electrostatic latent image on the surface of the image carrier, and developing the electrostatic latent image with a developer to form a toner image. A developing unit that forms the toner image, and a transfer unit that transfers the developed toner image to the transfer target. The developer for developing an electrostatic charge image is used as the developer. In addition, the image forming apparatus according to the present embodiment includes means other than those described above, for example, charging means for charging the image holding member, fixing means for fixing the toner image transferred to the surface of the transfer target, and the surface of the image holding member. Further, it may include a cleaning means for removing the remaining toner, carrier and the like.

  An example of the image forming apparatus according to the present embodiment is schematically shown in FIG. The image forming apparatus 1 includes a charging unit 10, an exposure unit 12, an electrophotographic photosensitive member 14 that is an image holding member, a developing unit 16, a transfer unit 18, a cleaning unit 20, and a fixing unit 22.

  In the image forming apparatus 1, the charging unit 10 that is a charging unit that charges the surface of the electrophotographic photosensitive member 14 and the charged electrophotographic photosensitive member 14 are exposed around the electrophotographic photosensitive member 14 according to image information. The exposure unit 12 is a latent image forming unit that forms an electrostatic latent image, the developing unit 16 is a developing unit that develops the electrostatic latent image with toner to form a toner image, and the surface of the electrophotographic photoreceptor 14. A transfer unit 18 that is a transfer unit that transfers the toner image formed on the surface of the transfer target 24, and a cleaning unit 20 that is a cleaning unit that removes toner remaining on the surface of the electrophotographic photosensitive member 14 after transfer. Are arranged in this order. A fixing unit 22 that is a fixing unit that fixes the toner image transferred to the transfer target 24 is arranged on the left side of the transfer unit 18.

  An operation of the image forming apparatus 1 according to the present embodiment will be described. First, the surface of the electrophotographic photosensitive member 14 is uniformly charged by the charging unit 10 (charging process). Next, light is applied to the surface of the electrophotographic photosensitive member 14 by the exposure unit 12, and the charged charges in the irradiated portion are removed, and an electrostatic charge image (electrostatic latent image) is formed according to the image information. (Latent image forming step). Thereafter, the electrostatic charge image is developed by the developing unit 16, and a toner image is formed on the surface of the electrophotographic photosensitive member 14 (developing step). For example, in the case of a digital electrophotographic copying machine using an organic photoconductor as the electrophotographic photoconductor 14 and using a laser beam as the exposure unit 12, the surface of the electrophotographic photoconductor 14 is negatively charged by the charging unit 10. Then, a digital latent image is formed in a dot shape by the laser beam light, and toner is applied to the portion irradiated with the laser beam light by the developing unit 16 to be visualized. In this case, a negative bias is applied to the developing unit 16. Next, a transfer member 24 such as paper is superposed on the toner image at the transfer unit 18, and a charge opposite in polarity to the toner is applied to the transfer member 24 from the back side of the transfer member 24, and the toner image is generated by electrostatic force. Is transferred to the transfer target 24 (transfer process). The transferred toner image is heated and pressed by a fixing member in the fixing unit 22 and is fused and fixed to the transfer target 24 (fixing step). On the other hand, toner remaining on the surface of the electrophotographic photoreceptor 14 without being transferred is removed by the cleaning unit 20 (cleaning step). One cycle is completed in a series of processes from charging to cleaning. In FIG. 1, the toner image is directly transferred to the transfer target 24 such as a sheet by the transfer unit 18, but may be transferred via a transfer member such as an intermediate transfer member.

  Hereinafter, the charging unit, the image carrier, the exposure unit, the developing unit, the transfer unit, the cleaning unit, and the fixing unit in the image forming apparatus 1 of FIG. 1 will be described.

(Charging means)
For example, a charging device such as a corotron as shown in FIG. 1 is used as the charging unit 10 as a charging unit, but a conductive or semiconductive charging roll may be used. A contact charger using a conductive or semiconductive charging roll may apply a direct current to the electrophotographic photosensitive member 14 or may superimpose an alternating current. For example, the charging unit 10 charges the surface of the electrophotographic photosensitive member 14 by generating a discharge in a minute space near the contact portion with the electrophotographic photosensitive member 14. Normally, it is charged to −300V or more and −1000V or less. The conductive or semiconductive charging roll may have a single layer structure or a multiple structure. Further, a mechanism for cleaning the surface of the charging roll may be provided.

(Image carrier)
The image carrier has a function of forming at least a latent image (electrostatic charge image). As the image carrier, an electrophotographic photosensitive member is preferably exemplified. The electrophotographic photoreceptor 14 has a coating film containing an organic photoreceptor or the like on the outer peripheral surface of a cylindrical conductive substrate. The coating film is formed by forming, in this order, a subbing layer, a charge generation layer containing a charge generation material, and a charge transport layer containing a charge transport material in this order on a substrate. is there. The order of stacking the charge generation layer and the charge transport layer may be reversed. These are laminated photoconductors in which a charge generation material and a charge transport material are contained in separate layers (charge generation layer, charge transport layer), but both the charge generation material and the charge transport material are the same. A single-layer type photoreceptor included in the above layer may be used, and a laminated photoreceptor is preferable. Further, an intermediate layer may be provided between the undercoat layer and the photosensitive layer. In addition, other types of photosensitive layers such as an amorphous silicon photosensitive film may be used in addition to the organic photoreceptor.

(Exposure means)
There is no particular limitation on the exposure unit 12 that is an exposure unit, and examples thereof include optical equipment that exposes a light source such as semiconductor laser light, LED light, and liquid crystal shutter light on the surface of the image carrier in a desired image manner. Can be mentioned.

(Development means)
The developing unit 16 serving as a developing unit has a function of developing a latent image formed on the image carrier with a developer containing toner to form a toner image. Such a developing device is not particularly limited as long as it has the above-mentioned function, and can be appropriately selected according to the purpose. For example, toner for developing an electrostatic image is used using a brush, a roller, or the like. A known developing device having a function of adhering to the electrophotographic photosensitive member 14 may be used. The electrophotographic photoreceptor 14 normally uses a DC voltage, but may be used with an AC voltage superimposed thereon.

(Transfer means)
As the transfer unit 18 serving as a transfer unit, for example, a charge having a polarity opposite to that of the toner is applied to the transfer target 24 from the back side of the transfer target 24 as shown in FIG. For example, a transfer roll and a transfer roll pressing device using a conductive or semiconductive roll or the like that transfers directly to the surface of the transfer target 24 via the transfer target 24 may be used. A direct current may be applied to the transfer roll as a transfer current applied to the image carrier, or an alternating current may be applied in a superimposed manner. The transfer roll may be arbitrarily set according to the width of the image area to be charged, the shape of the transfer charger, the opening width, the process speed (circumferential speed), and the like. Further, a single layer foam roll or the like is suitably used as a transfer roll for cost reduction. As a transfer method, a method of transferring directly to the transfer target 24 such as paper or a method of transferring to the transfer target 24 via an intermediate transfer member may be used.

  A known intermediate transfer member may be used as the intermediate transfer member. Materials used for the intermediate transfer member include polycarbonate resin (PC), polyvinylidene fluoride (PVDF), polyalkylene phthalate, PC / polyalkylene terephthalate (PAT) blend material, ethylene tetrafluoroethylene copolymer (ETFE) / PC, ETFE / PAT, PC / PAT blend materials, and the like can be mentioned. From the viewpoint of mechanical strength, an intermediate transfer belt using a thermosetting polyimide resin is preferable.

(Cleaning means)
The cleaning unit 20 serving as a cleaning unit may be appropriately selected such as one that employs a blade cleaning method, a brush cleaning method, or a roll cleaning method as long as the toner remaining on the image carrier is cleaned. Among these, it is preferable to use a cleaning blade having elasticity.

  The material of the cleaning blade is not particularly limited, and various elastic bodies may be used. Specific elastic bodies include elastic bodies such as polyurethane elastic bodies, silicone rubber, and chloroprene rubber. Among them, it is preferable to use a polyurethane elastic body because of its excellent wear resistance.

  As the polyurethane elastic body, a polyurethane generally synthesized through an addition reaction of an isocyanate with a polyol and various hydrogen-containing compounds may be used. This uses a polyether polyol such as polypropylene glycol or polytetramethylene glycol as a polyol component, or a polyester polyol such as an adipate polyol, polycaprolactam polyol or polycarbonate polyol, and a tolylene diisocyanate as an isocyanate component. Aromatic polyisocyanates such as 4,4′-diphenylmethane diisocyanate, polymethylene polyphenyl polyisocyanate, toluidine diisocyanate; aliphatic polyisocyanates such as hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, dicyclohexylmethane diisocyanate, etc. Prepare a urethane prepolymer, add a curing agent to it, and inject into a predetermined mold , After crosslinking and curing, it is prepared by aging at room temperature. As the curing agent, a dihydric alcohol such as 1,4-butanediol and a trihydric or higher polyhydric alcohol such as trimethylolpropane or pentaerythritol are usually used in combination.

(Fixing means)
The fixing unit 22 serving as a fixing unit (image fixing device) fixes the toner image transferred to the transfer medium 24 by heating, pressing, or heating and pressing, and includes a fixing member.

(Transfer)
Examples of the transfer target (paper) 24 to which the toner image is transferred include plain paper, OHP sheet, and the like used in electrophotographic copying machines, printers, and the like. In order to further improve the smoothness of the image surface after fixing, it is preferable that the surface of the transfer target is as smooth as possible. For example, coated paper in which the surface of plain paper is coated with resin, art paper for printing, etc. Is preferably used.

  Since the image forming apparatus and the image forming method according to the present embodiment use the electrostatic charge image developer (the carrier according to the present embodiment), an image having a stable image density can be formed over a long period of time.

  Hereinafter, although an example and a comparative example are given and the present invention is explained more concretely in detail, the present invention is not limited to the following examples.

[Toner Preparation]
<Preparation of resin particle dispersion>
Styrene 296 parts by mass n-butyl acrylate 104 parts by mass Acrylic acid 6 parts by mass Dodecanethiol 10 parts by mass Divinyl adipate 1.6 parts by mass (above, manufactured by Wako Pure Chemical Industries, Ltd.)
A mixture obtained by mixing and dissolving the above components was mixed with 12 parts by weight of a nonionic surfactant (Sanyo Kasei Co., Ltd .: Nonipol 400) and an anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd .: Neogen SC). ) 8 parts by mass of ammonium persulfate (manufactured by Wako Pure Chemical Industries, Ltd.) 8 parts by mass in a flask dissolved in 610 parts by mass of ion-exchanged water, dispersed in a flask, emulsified, and slowly mixed for 12 minutes 50 parts by mass of ion-exchanged water in which was dissolved was added, and nitrogen substitution was performed at 0.1 liter / min for 20 minutes. Thereafter, the contents in the flask are heated with an oil bath until the content reaches 70 ° C., and emulsion polymerization is continued for 6 hours, so that the resin particles are dispersed with a volume average particle size of 200 nm and a solid content concentration of 40% by mass. Liquid (1) was prepared. When a portion of the dispersion was left in an oven at 100 ° C. to remove moisture, DSC (Differential Scanning Calorimetry) measurement was performed. As a result, the glass transition temperature was 54 ° C., the weight average molecular weight was 34, 000.

<Preparation of Colorant Dispersion (C)>
C. I. Pigment Blue 15: 3 (phthalocyanine pigment, manufactured by Dainichi Seika Co., Ltd .: cyanine blue 4937) 100 parts by mass

Anionic surfactant (Neogen RK: manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 10 parts by mass Deionized water 490 parts by mass The above components are mixed and dissolved, and dispersed for 10 minutes using a homogenizer (manufactured by IKA: Ultra Tarrax). A colorant dispersion (C) was prepared.

<Preparation of release agent particle dispersion>
Paraffin wax (manufactured by Nippon Seiwa Co., Ltd .: HNP-9) 100 parts by weight Anionic surfactant (manufactured by Lion Co., Ltd .: Lipar 860K) 10 parts by weight Deionized water 390 parts by weight After mixing and dissolving the above components, Release agent particles obtained by dispersing using a homogenizer (IKA: Ultra Turrax), dispersing with a pressure discharge type homogenizer, and dispersing release agent particles (paraffin wax) having an average particle size of 220 nm. A dispersion was prepared.

<Manufacture of cyan toner A>
Resin particle dispersion 320 parts by weight Colorant dispersion (C) 80 parts by weight Release agent particle dispersion 96 parts by weight Aluminum sulfate (manufactured by Wako Pure Chemical Industries, Ltd.) 1.5 parts by weight Ion-exchanged water 1270 parts by weight The components were housed in a round stainless steel flask with a temperature control jacket, dispersed using a homogenizer (IKA: Ultra Tarrax T50) at 5,000 rpm for 5 minutes, transferred to the flask, and 25 ° C. , And left stirring for 4 minutes with 4 paddles. Thereafter, the mixture was heated with a mantle heater with stirring at a rate of 1 ° C./min until the inside reached 48 ° C., and held at 48 ° C. for 20 minutes. Next, 80 parts by mass of the resin particle dispersion was gradually added and maintained at 48 ° C. for 30 minutes, and then a 1N sodium hydroxide aqueous solution was added to adjust the pH to 6.5.

  Thereafter, the temperature was raised to 95 ° C. at a rate of 1 ° C./min and held for 30 minutes. A 0.1N aqueous nitric acid solution was added to adjust the pH to 4.8, and the mixture was allowed to stand at 95 ° C. for 2 hours. Thereafter, the 1N aqueous sodium hydroxide solution was further added to adjust the pH to 6.5 and left at 95 ° C. for 5 hours. Then, it cooled to 30 degreeC at 5 degree-C / min.

  The resulting toner particle dispersion was filtered, (A) 2,000 parts by mass of ion-exchanged water at 35 ° C. was added to the obtained toner particles, (B) allowed to stand for 20 minutes, and (C) then filtered. After the operations from (A) to (C) were repeated 5 times, the toner particles on the filter paper were transferred to a vacuum dryer and dried at 45 ° C. and 1,000 Pa or less for 10 hours. The reason why the pressure is 1,000 Pa or less is that the above-mentioned toner particles are in a water-containing state, and in the initial stage of drying, the water freezes even at 45 ° C. and then the water sublimates. This is because is difficult to be constant. However, it was stable at 100 Pa at the end of drying. After returning the inside of the dryer to normal pressure, this was taken out to obtain toner mother particles.

  To 100 parts by mass of the toner base particles, 1.5 parts by mass of a silica external additive (manufactured by Nippon Aerosil Co., Ltd .: RY-50) is added and mixed in a Henschel mixer at 3,000 rpm for 3 minutes. Toner A was obtained.

  The obtained cyan toner A had a D50v of 5.7 μm, a GSDv of 1.25, a shape factor SF1 of 132, and a glass transition temperature of 52 ° C.

[Preparation of resin coating solution for carrier]
<Preparation of resin coating solution A>
100 parts by mass of toluene and 15 parts by mass of a styrene-methacrylate copolymer 1 (component ratio 30:70, weight average molecular weight 200,000) were stirred with a stirrer for 60 minutes to obtain a resin coating solution A.

<Preparation of resin coating solution B>
100 parts by mass of toluene and 15 parts by mass of styrene-methacrylate copolymer 2 (component ratio 30:70, weight average molecular weight 120,000) were stirred with a stirrer for 60 minutes to obtain a resin coating solution B.

<Preparation of resin coating solution C>
100 parts by mass of toluene and 15 parts by mass of styrene-methacrylate copolymer 3 (component ratio 30:70, weight average molecular weight 205,000) were stirred with a stirrer for 60 minutes to obtain a resin coating solution C.

<Preparation of resin coating solution D>
100 parts by mass of toluene and 15 parts by mass of styrene-methacrylate copolymer 4 (component ratio 30:70, weight average molecular weight 115,000) were stirred with a stirrer for 60 minutes to obtain a resin coating solution D.

<Preparation of resin coating solution E>
100 parts by mass of toluene and 15 parts by mass of styrene-methacrylate copolymer 5 (component ratio 30:70, weight average molecular weight 195,000) were stirred with a stirrer for 60 minutes to obtain a resin coating solution E.

<Preparation of resin coating solution F>
100 parts by mass of toluene and 15 parts by mass of styrene-methacrylate copolymer 6 (component ratio 30:70, weight average molecular weight 125,000) were stirred with a stirrer for 60 minutes to obtain a resin coating solution F.

<Preparation of resin coating solution G>)
100 parts by mass of toluene and 15 parts by mass of polyester resin 1 (bisphenol A: dodecenyl succinic acid: terephthalic acid = 10 mol: 2 mol: 8 mol, weight average molecular weight 180,000) were stirred with a stirrer for 60 minutes to obtain a resin coating solution G. It was.

<Preparation of resin coating solution H>
100 parts by mass of toluene and 15 parts by mass of polyester resin 2 (bisphenol A: dodecenyl succinic acid: terephthalic acid = 10 mol: 2 mol: 8 mol, weight average molecular weight 100,000) were stirred with a stirrer for 60 minutes to obtain a resin coating solution H. It was.

<Preparation of resin coating solution I>
100 parts by mass of toluene and 15 parts by mass of polycyclohexyl acrylate 1 (weight average molecular weight 220,000) were stirred with a stirrer for 60 minutes to obtain a resin coating solution I.

<Preparation of resin coating solution J>
100 parts by mass of toluene and 15 parts by mass of polycyclohexyl acrylate 2 (weight average molecular weight 140,000) were stirred with a stirrer for 60 minutes to obtain a resin coating solution J.

<Preparation of resin coating solution K>
100 parts by mass of toluene and 15 parts by mass of polyamide resin 1 (p-diaminobenzene: terephthalic acid: succinic acid = 10 mol: 6 mol: 4 mol, weight average molecular weight 210,000) were stirred with a stirrer for 60 minutes, Obtained.

<Preparation of resin coating solution L>
100 parts by mass of toluene, 15 parts by mass of polyamide resin 2 (p-diaminobenzene: terephthalic acid: succinic acid = 10 mol: 6 mol: 4 mol, weight average molecular weight 130,000) were stirred with a stirrer for 60 minutes, and resin coating solution L was Obtained.

<Preparation of resin coating solution M>
100 parts by mass of toluene and 15 parts by mass of styrene-methacrylate copolymer 7 (component ratio 30:70, weight average molecular weight 105,000) were stirred with a stirrer for 60 minutes to obtain a resin coating solution M.

<Preparation of resin coating solution N>
100 parts by mass of toluene and 15 parts by mass of styrene-methacrylate copolymer 8 (component ratio 30:70, weight average molecular weight 135,000) were stirred with a stirrer for 60 minutes to obtain a resin coating solution N.

<Preparation of resin coating solution O>
100 parts by mass of toluene and 15 parts by mass of a styrene-methacrylate copolymer 9 (component ratio 30:70, weight average molecular weight 170,000) were stirred with a stirrer for 60 minutes to obtain a resin coating solution O.

[Preparation of core particle 1]
Into a Henschel mixer, 500 parts by mass of spherical magnetite particle powder having a volume average particle size of 0.5 μm is added, and after sufficient stirring, 5.0 parts by mass of titanate coupling agent is added, and the temperature is raised to about 100 degrees. By mixing and stirring for 30 minutes, spherical magnetite particles coated with a titanate coupling agent were obtained.

  Subsequently, 6.25 parts by mass of phenol, 9.25 parts by mass of 35% formalin, 500 parts by mass of the magnetite particles, 6.25 parts by mass of 25% aqueous ammonia, and 428 parts by mass of water are placed in a 1 L four-necked flask. , Mixed and stirred. Next, the temperature is raised to 85 ° C. over 60 minutes with stirring and reacted at the same temperature for 120 minutes, then cooled to 25 ° C., 500 ml of water is added, the supernatant is removed, and the precipitate is washed with water. did. This was dried at 150 ° C. or higher and 180 ° C. or lower under reduced pressure to obtain core material particles 1 having a volume average particle size of 35 μm.

Example 1
[Preparation of carrier]
Resin coating solution A 133.28 parts by mass, resin coating solution B 33.32 parts by mass, carbon black (Regal 330: manufactured by Cabot) 1.5 parts by mass using a homogenizer (IKA: Ultra Turrax) 5 The mixture is stirred at 1,000 rpm for 10 minutes to prepare dispersion 1, put in a vacuum degassing type kneader together with 1000 parts by mass of the core material particles 1, stirred at 90 ° C. for 30 minutes, further set the temperature to 70 ° C., and 65 kPa After stirring for 5 minutes at 70 kPa for 3 minutes, the pressure was further reduced to deaerate and dry. Further, carrier A was prepared by passing through a mesh having an opening of 75 μm.

[Developer preparation]
8 parts by mass of cyan toner A and 100 parts by mass of carrier A were mixed in a V blender for 30 minutes and then sieved to obtain developer A.

  The developer A is air blown to remove the toner, and the remaining carrier is observed with a transmission electron microscope under the conditions described above, and the resin coating layer portion of the cross section of the carrier is observed. Was formed, and it was confirmed that the sea part and the island part each contained conductive particles. The ratio of the sea part to the island part was 80:20, the average dispersion diameter DirS of the conductive particles in the sea part was 45 nm, and the average dispersion diameter DirI of the conductive particles in the island part was 150 nm.

[Evaluation]
Developer A was set on a DocuCentreColor400CP remodeled machine manufactured by Fuji Xerox Co., Ltd., and the image condition after forming 50,000 sheets at a development process speed of 200 mm / sec was evaluated according to the following criteria. The results are shown in Table 1.
◎: No image density problem ○: Image density is slightly uneven (thin part), but there is no problem ×: Image density is low

(Example 2)
Carrier B and developer in the same manner as in Example 1 except that 121.6 parts by mass of resin coat solution C instead of resin coat solution A and 45.0 parts by mass of resin coat solution D instead of resin coat solution B B was obtained. The ratio of the sea part to the island part was 73:27, the average dispersion diameter DirS of the conductive particles in the sea part was 32 nm, and the average dispersion diameter DirI of the conductive particles in the island part was 200 nm. Evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

Example 3
Carrier C and developer in the same manner as in Example 1 except that 146.6 parts by mass of resin coat solution E instead of resin coat solution A and 20.0 parts by mass of resin coat solution F instead of resin coat solution B C was obtained. The ratio of the sea part to the island part was 88:12, the average dispersion diameter DirS of the conductive particles in the sea part was 58 nm, and the average dispersion diameter DirI of the conductive particles in the island part was 110 nm. Evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

Example 4
In the same manner as in Example 1 except that the amount of the resin coat solution A is 120.0 parts by mass, the amount of the resin coat solution B is 46.6 parts by mass, and the number of revolutions of the homogenizer is 4,000 rpm, the carrier D, Developer D was obtained. The ratio of the sea part to the island part was 72:28, the average dispersion diameter DirS of the conductive particles in the sea part was 59 nm, and the average dispersion diameter DirI of the conductive particles in the island part was 205 nm. Evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

(Example 5)
In the same manner as in Example 1 except that the amount of the resin coat solution A was 145.0 parts by mass, the amount of the resin coat solution B was 21.7 parts by mass, and the rotation speed of the homogenizer was 6,000 rpm, the carrier E, Developer E was obtained. The ratio of the sea part to the island part was 87:13, the average dispersion diameter DirS of the conductive particles in the sea part was 31 nm, and the average dispersion diameter DirI of the conductive particles in the island part was 108 nm. Evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

(Example 6)
Carrier F and developer in the same manner as in Example 1 except that the resin coat solution G is used instead of the resin coat solution A, the resin coat solution H is used instead of the resin coat solution B, and the rotation speed of the homogenizer is 6,000 rpm. F was obtained. The ratio of the sea part to the island part was 80:20, the average dispersion diameter DirS of the conductive particles in the sea part was 44 nm, and the average dispersion diameter DirI of the conductive particles in the island part was 152 nm. Evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

(Example 7)
Resin coat solution I, resin coat solution B instead of resin coat solution A, resin coat solution J instead of resin coat solution B, and carrier G, developer as in Example 1 except that the number of revolutions of the homogenizer was 4,000 rpm. G was obtained. The ratio of the sea part to the island part was 80:20, the average dispersion diameter DirS of the conductive particles in the sea part was 46 nm, and the average dispersion diameter DirI of the conductive particles in the island part was 148 nm. Evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

(Example 8)
Resin coat solution K instead of resin coat solution A, resin coat solution L instead of resin coat solution B, and carrier H, developer as in Example 1 except that the rotation speed of the homogenizer was changed to 4,500 rpm. H was obtained. The ratio of the sea part to the island part was 80:20, the average dispersion diameter DirS of the conductive particles in the sea part was 43 nm, and the average dispersion diameter DirI of the conductive particles in the island part was 151 nm. Evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

Example 9
A carrier I and a developer I were obtained in the same manner as in Example 1 except that the resin coat solution M was used instead of the resin coat solution B, and the rotation speed of the homogenizer was 6,000 rpm. The ratio of the sea part to the island part was 80:20, the average dispersion diameter DirS of the conductive particles in the sea part was 32 nm, and the average dispersion diameter DirI of the conductive particles in the island part was 205 nm. Evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

(Example 10)
A carrier J and a developer J were obtained in the same manner as in Example 1 except that the resin coat solution N was used instead of the resin coat solution B, and the homogenizer rotation speed was 4,000 rpm. The ratio of the sea part to the island part was 80:20, the average dispersion diameter DirS of the conductive particles in the sea part was 58 nm, and the average dispersion diameter DirI of the conductive particles in the island part was 105 nm. Evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 1)
Carrier K and developer K were obtained in the same manner as in Example 1 except that the rotation speed of the homogenizer was 7,000 rpm. The ratio of the sea part to the island part was 80:20, the average dispersion diameter DirS of the conductive particles in the sea part was 25 nm, and the average dispersion diameter DirI of the conductive particles in the island part was 90 nm. Evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 2)
Carrier L and developer L were obtained in the same manner as in Example 1 except that the number of rotations of the homogenizer was 3,000 rpm. The ratio of the sea part to the island part was 80:20, the average dispersion diameter DirS of the conductive particles in the sea part was 65 nm, and the average dispersion diameter DirI of the conductive particles in the island part was 215 nm. Evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 3)
Carrier M and developer M were obtained in the same manner as in Example 1 except that the amount of the resin coating solution A was 100.0 parts by mass and the amount of the resin coating solution B was 66.6 parts by mass. The ratio of the sea part to the island part was 60:40, the average dispersion diameter DirS of the conductive particles in the sea part was 46 nm, and the average dispersion diameter DirI of the conductive particles in the island part was 151 nm. Evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 4)
Carrier N and developer N were obtained in the same manner as in Example 1 except that the amount of the resin coating solution A was 158.3 parts by mass and the amount of the resin coating solution B was 8.3 parts by mass. The ratio of the sea part to the island part was 95: 5, the average dispersion diameter DirS of the conductive particles in the sea part was 45 nm, and the average dispersion diameter DirI of the conductive particles in the island part was 149 nm. Evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 5)
Carrier O and developer O were obtained in the same manner as in Example 1 except that the amount of the resin coating solution A was 166.6 parts by mass and the resin coating solution B was not used. Sea-island structure was not observed. The average dispersion diameter Dir of the conductive particles was 45 nm. Evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 6)
A carrier P and a developer P were obtained in the same manner as in Example 1 except that the resin coat solution O was used instead of the resin coat solution B. Sea-island structure was not observed. The average dispersion diameter Dir of the conductive particles was 57 nm. Evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

  As described above, by using the carriers of Examples 1 to 10, an image having a stable image density was formed over a long period of time even in low-consumption printing.

  DESCRIPTION OF SYMBOLS 1 Image forming apparatus, 10 charging part, 12 exposure part, 14 electrophotographic photosensitive member, 16 developing part, 18 transfer part, 20 cleaning part, 22 fixing part, 24 to-be-transferred body.

Claims (3)

A carrier core material, and a resin coating layer covering the surface of the carrier core material;
In the resin coating layer, the resin forms a sea-island structure in which the sea part and the island part are phase-separated, and each of the sea part and the island part contains conductive particles,
The ratio of the sea part to the island part confirmed in the transmission electron microscope observation is in the range of 80:20 or more and 90:10 or less, and the average dispersion diameter of the conductive particles in the sea part confirmed in the transmission electron microscope observation. A carrier for developing an electrostatic charge image, wherein DirS is in the range of 30 nm to 60 nm and the average dispersion diameter DirI of the conductive particles in the island is in the range of 100 nm to 210 nm.   An electrostatic charge image developing developer comprising the electrostatic charge image developing carrier according to claim 1 and an electrostatic charge image developing toner. An image carrier, a latent image forming unit that forms an electrostatic latent image on the surface of the image carrier, a developing unit that develops the electrostatic latent image using a developer to form a toner image, and the development A transfer means for transferring the toner image thus transferred to a transfer medium,
An image forming apparatus, wherein the developer is the developer for developing an electrostatic image according to claim 2.

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