JP2019211634A - Toner for electrostatic latent image development, two-component developer for electrostatic charge image development, and image forming method - Google Patents

Abstract

To provide a toner for electrostatic latent image development that, even when high-speed printing is performed under an HH environment, prevents the occurrence of fogging and scattering, is excellent in fine line reproducibility, and is excellent in electrostatic separability during fixing.SOLUTION: A toner for electrostatic latent image development has toner base particles containing a binder resin and a colorant, and an external additive. The external additive includes zinc oxide fine particles doped with aluminum or gallium and subjected to surface treatment.SELECTED DRAWING: None

Description

  The present invention relates to a toner for developing an electrostatic latent image, a two-component developer for developing an electrostatic image, and an image forming method.

  Conventionally, in electrophotographic image formation, as a toner for developing an electrostatic charge image (hereinafter, also simply referred to as “toner”) for stably forming an image over a long period of time, zinc oxide is externally applied on the surface of toner base particles. Toner added as an additive is known (for example, see Patent Document 1).

  Patent Document 1 describes a toner having toner base particles and an external additive. The external additive is zinc oxide doped with aluminum (Al-ZnO). Since Al—ZnO has a function equivalent to that of titanium oxide, image formation using the toner described in Patent Document 1 can stably form an image over a long period of time.

JP 2009-139663 A

  However, in the toner described in Patent Document 1, water molecules adsorbed on the surface of Al—ZnO in a high-temperature and high-humidity environment lower the surface resistance value of the toner base particles, and further promote charge leakage of the toner base particles. Therefore, there is a problem that the charge amount is lowered, causing scattering and fogging. The toner described in Patent Document 1 is manufactured by a kneading and pulverizing method. Since the toner produced by the kneading and pulverizing method has a pulverized shape, it is difficult for the external additive to adhere uniformly. For this reason, the toner produced by the kneading and pulverization method has a wide charge amount distribution, and therefore, in the image formation using a high-speed machine with a high linear speed and high consumption, dust and the like in the fine line portion are generated, and the formed image There was a problem that the image quality deteriorated.

  Further, there is a problem that the recording media after double-sided printing using toner manufactured by the kneading and pulverizing method are electrostatically stuck to each other at the paper discharge receiving portion and cannot be easily peeled off. In addition, the toner produced by the kneading and pulverization method has extremely low moisture in the toner particles depending on the kneading temperature during the production, and therefore, in the toner image generated after fixing, the charge cannot leak to the charge on the image surface. . As a result, there is a problem in that the upper and lower images are adhered to each other by the electrostatic attraction due to the electric charge remaining on the image formed on the recording medium, and are adhered to each other.

  Therefore, an object of the present invention is to prevent electrostatic fogging and scattering even when printing at high speed in a high-temperature and high-humidity environment, excellent in fine line reproducibility, and excellent in electrostatic peeling at fixing. To provide a toner for image development. Another object of the present invention is to provide a two-component developer for developing an electrostatic image having toner for developing an electrostatic latent image. Furthermore, another object of the present invention is to provide an image forming method using the electrostatic latent image developing toner or the electrostatic charge image developing two-component developer.

  The present invention has, as one means for solving the above-described problems, toner base particles containing a binder resin and a colorant, and an external additive, and the external additive is doped with aluminum or gallium, An electrostatic latent image developing toner containing surface-treated zinc oxide fine particles is provided.

  The present invention also includes, as one means for solving the above-described problems, an electrostatic charge image developing toner and carrier particles, and the electrostatic latent image developing toner is the electrostatic latent image development described above. Provided is a two-component developer for developing an electrostatic image, which is a toner for use in an electrostatic charge.

  In addition, as a means for solving the above-described problems, the present invention uses an electrophotographic system that uses the above-described electrostatic latent image developing toner or the above-described two-component developer for developing electrostatic images. An image forming method is provided.

  According to the present invention, even when high-speed printing is performed in a high-temperature and high-humidity environment, fog and scattering do not occur, the fine line reproducibility is excellent, and the electrostatic latent image development that is excellent in electrostatic peelability during fixing Toner can be provided. In addition, a two-component developer for developing an electrostatic image having toner for developing an electrostatic latent image can be provided. Furthermore, an image forming method using the electrostatic latent image developing toner or the electrostatic charge image developing two-component developer can be provided.

FIG. 1 is a diagram for explaining measurement of the average charge amount.

[Configuration of toner for developing electrostatic latent image]
The electrostatic latent image developing toner is a so-called two-component developer and is composed of toner particles. The toner particles include toner base particles and an external additive attached to the surface of the toner base particles. The toner base particles have a binder resin and a colorant.

(Binder resin)
The binder resin includes an amorphous resin. The binder resin may further contain a crystalline resin.

  An amorphous resin has substantially no crystallinity, and includes, for example, an amorphous part in the resin. Examples of the amorphous resin include vinyl resins, urethane resins, urea resins, amorphous polyester resins, and partially modified polyester resins. The amorphous resin can be synthesized, for example, by a known method. One type of amorphous resin may be used alone, or two or more types may be used in combination. The amorphous resin preferably contains a vinyl resin.

  A vinyl resin is a resin produced by polymerization of a monomer containing a compound having a vinyl group or a derivative thereof. One type of vinyl resin may be used alone, or two or more types may be used in combination. Examples of vinyl resins include styrene- (meth) acrylic resins.

  The styrene- (meth) acrylic resin has a molecular structure of a radical polymer of a compound having a radical polymerizable unsaturated bond. The styrene- (meth) acrylic resin can be synthesized, for example, by radical polymerization of a compound having a radical polymerizable unsaturated bond. As the compound having a radical polymerizable unsaturated bond, one kind may be used alone, or two or more kinds may be used in combination. Examples of the compound having a radical polymerizable unsaturated bond include styrene and derivatives thereof, and (meth) acrylic acid and derivatives thereof.

  Examples of styrene and its derivatives include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, p-ethylstyrene, pn- Butyl styrene, p-tert-butyl styrene, pn-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene, 2,4-dimethyl Styrene and 3,4-dichlorostyrene are included.

  Examples of (meth) acrylic acid and its derivatives include methyl acrylate, ethyl acrylate, butyl acrylate, acrylate-2-ethylhexyl, cyclohexyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, methacrylic acid Examples include butyl, hexyl methacrylate, 2-ethylhexyl methacrylate, ethyl β-hydroxyacrylate, propyl γ-aminoacrylate, stearyl methacrylate, dimethylaminoethyl methacrylate and diethylaminoethyl methacrylate.

  The content of the vinyl resin in the amorphous resin is preferably 50% by mass or more, more preferably 60% by mass or more, and further preferably 70% by mass or more. In this embodiment, the effect is large when the compatibility between the amorphous resin and the crystalline resin is low. In particular, the effect is large when a vinyl resin is contained as a main component of the amorphous resin and a crystalline resin (crystalline polyester resin) is dispersed in the resin. In addition, in the step of forming particles by aggregating the binder resin in an aqueous solvent, it is possible to prevent the dispersion state of the crystalline resin in the amorphous resin from becoming insufficient.

  The crystalline resin is a resin having crystallinity. Here, “crystallinity” means that in differential scanning calorimetry (DSC), it has a clear endothermic peak, not a stepwise endothermic change. The “clear endothermic peak” specifically means a peak in which the half-value width of the endothermic peak is within 15 ° C. when measured at a heating rate of 10 ° C./min in DSC. Note that the smaller the half-value width of the endothermic peak, the higher the crystallinity.

  The crystalline resin is preferably a crystalline polyester resin from the viewpoint of good low-temperature fixability. The melting point of the crystalline polyester resin is preferably 50 to 85 ° C. from the viewpoint of sufficiently softening the toner and ensuring sufficient low-temperature fixability, and further 60 to 80 ° C. from the viewpoint of improving various properties in a balanced manner. More preferred. The melting point of the crystalline polyester resin can be controlled by the resin composition (for example, the type of monomer). One type of crystalline polyester resin may be used, or two or more types may be used in combination.

  Crystalline polyester can be manufactured by the well-known synthesis method by the dehydration condensation reaction of polyhydric carboxylic acid and polyhydric alcohol, for example.

  Examples of polyvalent carboxylic acids include saturated aliphatic dicarboxylic acids such as succinic acid, sebacic acid and dodecanedioic acid; alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid; aromatic dicarboxylic acids such as phthalic acid, isophthalic acid and terephthalic acid Acid; trivalent or higher polyvalent carboxylic acids such as trimellitic acid and pyromellitic acid; acid anhydrides thereof; and alkyl esters having 1 to 3 carbon atoms thereof. The polyvalent carboxylic acid is preferably an aliphatic dicarboxylic acid.

  Examples of polyhydric alcohols include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7 -Aliphatic diols such as heptanediol, 1,8-octanediol, neopentylglycol, 1,4-butenediol; and trihydric or higher alcohols such as glycerin, pentaerythritol, trimethylolpropane, sorbitol; It is. The polyhydric alcohol is preferably an aliphatic diol.

  The crystalline resin is more preferably a hybrid crystalline polyester resin. The hybrid crystalline polyester resin has a structure in which a crystalline polyester resin unit and an amorphous resin unit are chemically bonded.

  The “crystalline polyester resin unit” refers to a portion derived from the crystalline polyester resin in the hybrid crystalline polyester resin. The “amorphous resin unit” refers to a portion derived from a resin having no crystallinity (amorphous resin) in the hybrid crystalline polyester resin.

  As the crystalline polyester resin, the above-described crystalline polyester resin can be used. As the amorphous resin, the above-mentioned amorphous resin can be used.

  In the hybrid crystalline polyester resin, the crystalline polyester resin unit and the amorphous resin unit are crystalline polyester resin units, amorphous resin units, or a range in which these resins are chemically bonded. Any of them may be arranged continuously or randomly. Moreover, both units may be connected in a chain form, or the other may be grafted to one chain.

  The chemical bond is, for example, an ester bond or a covalent bond by an addition reaction of an unsaturated group. The hybrid crystalline polyester resin can be obtained by a known method in which a crystalline polyester resin unit and an amorphous resin unit are bonded by chemical bonding.

  Furthermore, substituents such as sulfonic acid groups, carboxyl groups, and urethane groups can be further introduced into the hybrid crystalline polyester resin. The introduction site of the substituent may be a crystalline polyester resin unit or an amorphous resin unit.

  The structure and amount of the main chain and side chain in the obtained resin are, for example, known instrumental analysis such as nuclear magnetic resonance (NMR) and electrospray ionization mass spectrometry (ESI-MS) of the binder resin or its hydrolyzate. Can be confirmed or estimated using the law.

  In the synthesis of the resin unit described above, a chain transfer agent for adjusting the molecular weight of the obtained resin may be further included in a raw material such as a monomer of the resin unit. A chain transfer agent may be used individually by 1 type, and may use 2 or more types together. Examples of chain transfer agents include 2-chloroethanol, octyl mercaptans, dodecyl mercaptans, mercaptans such as t-dodecyl mercaptan, and styrene dimers.

  Here, the “graft bond” means a chemical bond between a polymer serving as a trunk and a different kind of polymer (or monomer) serving as a branch. The hybrid crystalline polyester resin preferably has a structure in which a crystalline polyester resin unit is graft-bonded to an amorphous resin unit from the viewpoint of comprehensively improving desired properties of the toner.

  The contents of the crystalline polyester resin unit and the amorphous resin unit in the hybrid crystalline polyester resin can be appropriately determined within a range where the effects of the present embodiment can be obtained. For example, if the content of the amorphous resin unit in the hybrid crystalline polyester resin is too low, the dispersion of the hybrid crystalline polyester resin in the toner base particles may be insufficient. It may be insufficient. From such a viewpoint, the content is preferably 5 to 30% by mass, and more preferably 5 to 20% by mass from the viewpoint of improving high-temperature storage stability and charging uniformity.

  From the same viewpoint, the content of the crystalline polyester resin unit in the hybrid crystalline polyester resin is preferably 65 to 95% by mass, and more preferably 70 to 90% by mass. Moreover, the hybrid crystalline polyester resin may further contain components other than both units as long as the effects of the present embodiment can be obtained. Examples of other components include various additives to be added to other resin units and toner base particles.

(Coloring agent)
As the colorant, a known inorganic or organic colorant used as a colorant colorant can be used. Examples of the colorant include carbon black, a magnetic material, a pigment, and a dye. A colorant may be used individually by 1 type and may use 2 or more types together.

  Examples of carbon black include channel black, furnace black, acetylene black, thermal black and lamp black. Examples of the magnetic material include ferromagnetic metals such as iron, nickel, and cobalt, alloys containing these metals, and compounds of ferromagnetic metals such as ferrite and magnetite.

  Examples of pigments include C.I. I. Pigment Red 2, 3, 5, 7, 15, 16, 48: 1, 48: 3, 53: 1, 57: 1, 81: 4, 122, 123, 139, 144, 149, 166, 177, 178, 208, 209, 222, 238, 269, C.I. I. Pigment Orange 31 and 43, C.I. I. Pigment Yellow 3, 9, 14, 17, 35, 36, 65, 74, 83, 93, 94, 98, 110, 111, 138, 139, 153, 155, 180, 181, 185, C.I. I. Pigment green 7, C.I. I. Pigment Blue 15: 3, 15: 4, 60, and phthalocyanine pigments whose central metal is zinc, titanium, magnesium or the like.

  Examples of dyes include C.I. I. Solvent Red 1, 3, 14, 17, 17, 22, 22, 49, 51, 52, 58, 63, 87, 111, 122, 127, 128, 131, 145, 146, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 176, 179, pyrazolotriazole Azo dyes, pyrazolotriazole azomethine dyes, pyrazolone azo dyes, pyrazolone azomethine dyes, C.I. I. Solvent Yellow 19, 44, 77, 79, 81, 82, 93, 98, 103, 104, 112, 162, C.I. I. Solvent Blue 25, 36, 60, 70, 93 and 95 are included.

  The content of each resin or each unit in the binder resin is specified using a known instrumental analysis method such as NMR or methylation reaction pyrolysis-gas chromatograph / mass spectrometry (P-GC / MS). Or can be estimated.

(Other ingredients)
As described above, the toner has toner base particles containing a binder resin and a colorant. The toner base particles may further contain other components as long as the effects of the present embodiment are exhibited. Examples of other components include release agents and charge control agents. Other components may be used alone or in combination of two or more.

  Examples of the release agent (wax) include hydrocarbon waxes and ester waxes. Examples of the hydrocarbon wax include low molecular weight polyethylene wax, low molecular weight polypropylene wax, Fischer-Tropsch wax, microcrystalline wax and paraffin wax. Examples of the ester wax include carnauba wax, pentaerythritol behenate, behenyl behenate and behenyl citrate.

  Examples of the charge control agent include nigrosine dyes, naphthenic acid or higher fatty acid metal salts, alkoxylated amines, quaternary ammonium salt compounds, azo metal complexes, and salicylic acid metal salts or metal complexes thereof.

  The toner base particles are preferably polymerized toners prepared in an aqueous medium rather than pulverized toners from the viewpoint of appropriate control of the particle size and circularity, and are toner base particles by an emulsion association aggregation method. Is more preferable.

(External additive)
As described above, the toner particles have the toner base particles and the external additive present on the surface thereof. The external additive contains zinc oxide fine particles doped with aluminum and surface-treated, or zinc oxide fine particles doped with gallium and surface-treated.

  The zinc oxide fine particles contain aluminum or gallium in a zinc oxide crystal in a solid solution state. The content of aluminum or gallium in terms of metal with respect to zinc oxide is preferably 0.01 to 10% by mass, more preferably 0.05% by mass or more and 5% by mass or less, and 0.1% by mass or more. 3 mass% or less is especially preferable.

  The method for doping aluminum or gallium into zinc oxide fine particles is not particularly limited. Aluminum or gallium can be doped into the zinc oxide fine particles by the following method, for example.

The method of doping aluminum or gallium is
(1) reacting an alkali carbonate with an aqueous slurry of zinc oxide to obtain basic zinc carbonate;
(2) heating and aging basic zinc carbonate;
(3) a step of mixing the obtained ripening solution with a water-soluble salt of aluminum or gallium and re-ripening;
(4) dehydrating and drying the aged product;
(5) a step of firing the obtained dried product;
(6) crushing the fired product;
Have

  First, an alkali carbonate (or a compound that decomposes to produce carbon dioxide and alkali) (hereinafter referred to as an alkali carbonate) is added to an aqueous slurry containing zinc oxide to produce basic zinc carbonate. (Hereinafter, also referred to as “basic zinc carbonate production step”).

  The preparation method of the zinc oxide used is not specifically limited. Examples of preparation methods for zinc oxide include (1) French method in which zinc is melted and evaporated and oxidized in the gas phase, (2) American method in which zinc ore is calcined, reduced and then oxidized, (3) It includes a wet method (thermal decomposition method) in which soda ash is added to a zinc salt solution to precipitate basic zinc carbonate, which is dried and then fired. In order to obtain high-purity zinc oxide fine particles, it is preferable to use high-purity zinc oxide.

  Water used when zinc oxide is suspended to form an aqueous slurry is not particularly limited. The content of zinc oxide in the aqueous slurry is preferably 0.1% by mass or more and 10% by mass or less, more preferably 0.5% by mass or more and 8% by mass or less, and particularly preferably 1% by mass or more and 5% by mass or less. preferable. When the content is more than 10% by mass, basic zinc carbonate having a large particle diameter may be generated, or an aggregate in which primary particles are strongly aggregated in a planar shape may be generated. On the other hand, when the content is less than 0.1% by mass, the amount of water to be removed becomes excessive, and productivity and energy efficiency may be reduced.

  Moreover, the kind of alkali carbonate to be used is not particularly limited. Examples of the alkali carbonate include sodium carbonate, sodium bicarbonate, ammonium carbonate, and ammonium bicarbonate. One alkali carbonate may be used alone, or two or more may be used in combination.

  The water temperature when dissolving the alkali carbonate is preferably 30 ° C. or less, more preferably 20 ° C. or less, from the viewpoint of suppressing the generation of carbon dioxide gas due to thermal decomposition.

  The reaction apparatus used in the step of producing basic zinc carbonate is not particularly limited. For example, the reaction apparatus has a stirring means, a heating means, a cooling means, etc. A stirring tank type reactor having a function capable of efficiently proceeding the reaction with the zinc oxide fine particles by maintaining and introducing an alkali carbonate is preferable.

  The method for producing basic zinc carbonate is not particularly limited. Examples of the method for producing basic zinc carbonate include, for example, a semi-continuous method (semi-batch method) in which a basic zinc carbonate slurry is produced by continuously supplying an alkali carbonate solution to a zinc oxide slurry in a reaction vessel. ), A continuous method in which both a zinc oxide slurry and an alkali carbonate solution are continuously supplied to a reaction vessel to produce a basic zinc carbonate slurry, and the produced basic zinc carbonate slurry is continuously extracted from the reaction vessel. included. When the method is a continuous method, one reaction tank may be used, or a reaction tank in which two or more tanks are connected in series may be used.

  The reaction temperature when producing basic zinc carbonate is not particularly limited. The reaction temperature is preferably 10 ° C. or higher and 80 ° C. or lower, more preferably 20 ° C. or higher and 70 ° C. or lower, from the viewpoint of suppressing the yield reduction of basic zinc carbonate by generating carbon dioxide gas. Also, the reaction time is not particularly limited. The reaction time is preferably 10 minutes to 10 hours, more preferably 30 minutes to 5 hours.

  In the dehydration step, a centrifugal dehydrator, a filter press, a belt filter, a Nutsche filter, a screw press, a belt press, a spray dryer, or the like can be used.

The firing step may be performed in an oxidizing atmosphere or in a non-oxidizing atmosphere. When it is desired to reduce the volume resistivity of the zinc oxide fine particles, it is preferably performed in a reducing atmosphere. The firing temperature is preferably 300 ° C. or higher and 600 ° C. or lower, more preferably 350 ° C. or higher and 500 ° C. or lower, and particularly preferably 350 ° C. or higher and 450 ° C. or lower. If the firing temperature is too high, the dispersibility becomes poor. On the other hand, when the firing temperature is less than 300 ° C., the volume resistivity as the zinc oxide fine particles may exceed 10 ¹⁰ Ω · cm.

  As another manufacturing method, it can also be manufactured in a gas phase. (For example, Japanese Patent Application No. 2004-526723). In this manufacturing method, an evaporation step, a nucleation step, an oxidation step, and a quenching step are continuously performed. Zinc oxide and at least one doping component are nucleated and oxidized in the evaporation zone by evaporating the zinc powder in an air and / or oxygen flame and in a combustion gas, preferably hydrogen.

  Both the zinc oxide fine particles doped with aluminum or the zinc oxide fine particles doped with gallium are surface-treated. The surface-treated zinc oxide fine particles can improve the electrical characteristics of the electric charge flowing between the toner and the carrier. Specifically, it is possible to provide a potential barrier on the surface against the low resistance value of the zinc oxide fine particles, particularly in HH environment (30 ° C., 80% RH) and NN environment (20 ° C., 50% RH). Excessive charge leakage can be suppressed. Under the LL environment (10 ° C., 20% RH), the charge can be passed over the potential barrier against the excessive charging of the toner base particles, and as a result, the environmental difference in the charge amount as the toner base particles is small. Become. Here, “surface treatment” means that at least a part of the surface of the zinc oxide fine particles is modified with a material different from the inside to a state different from the inside of the fine particles. Since the surface treatment is to provide a potential barrier on the surface of the zinc oxide fine particles, a surface treatment technique is used in which the resistance value of the zinc oxide fine particles after the treatment is higher than that of the zinc oxide fine particles not subjected to the surface treatment.

  The modification form of the material surface by the surface treatment is roughly classified into a removal process and an additional process. Examples of the surface treatment by the removal processing include a treatment method for removing the deposit on the material surface or the material itself. Examples of surface treatment by additional processing include “high-frequency quenching” and “flame quenching” that change the metal structure without changing the chemical composition of the surface; “anodic oxidation” and “chemical conversion treatment” that chemically react on the surface; “Plating”, “Coating”, “Lining”, “Sputtering” for depositing other materials; “Carburizing”, “Nitriding” for soaking other elements from the surface; In addition, “hot dip galvanizing” and “thermal CVD” that impregnate elements at the boundary with the base material; “cleaning” and “rust removal” used as pretreatments; only specific parts of the surface physically or chemically “Etching” for shaving and patterning; “electropolishing” and “chemical polishing” for mirroring the surface. In addition, since the metal oxide containing undoped zinc oxide fine particles has a high resistance value compared to the doped zinc oxide fine particles, zinc or It also includes forming a zinc oxide film or metal oxide film on the surface by RF magnetron sputtering using another metal plate as an electrode (= target). Further, surface treatment with a surface treatment agent is also included. In the present embodiment, from the viewpoint that the zinc oxide fine particles are fine particles, sputtering, chemical conversion treatment, and surface treatment with a surface treatment agent are preferable.

  The zinc oxide fine particles surface-treated with the surface treatment agent have zinc oxide fine particles and a surface treatment agent residue arranged on the surface. The surface treatment agent includes a reaction portion that reacts with the hydroxyl group on the surface of the zinc oxide fine particles and a non-reacting portion that does not react with the hydroxyl group on the surface of the zinc oxide fine particles. By surface-treating the zinc oxide fine particles with the surface treatment agent, the surface treatment agent residue is arranged on the surface of the zinc oxide fine particles. The surface treatment agent residue can be selected depending on the surface treatment agent to be selected.

  The type of the surface treatment agent is not particularly limited as long as the above effects can be imparted. Examples of hydrophobizing agents include silylating agents such as methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, phenyltrichlorosilane, diphenyldichlorosilane, t-butyldimethylchlorosilane, chlorosilanes such as vinyltrichlorosilane, and tetramethoxysilane. , Methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, o-methylphenyltrimethoxysilane, p-methylphenyltrimethoxysilane, n-butyltrimethoxysilane, i-butyltrimethoxysilane, hexyl Trimethoxysilane, Octyltrimethoxysilane, Decyltrimethoxysilane, Dodecyltrimethoxysilane, Tetraethoxysilane, Methyltriethoxysilane, Di Tildiethoxysilane, phenyltriethoxysilane, diphenyldiethoxysilane, i-butyltriethoxysilane, decyltriethoxysilane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane , Γ-glycidoxypropylmethyldimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-chloropropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ- (2-aminoethyl) ) Alkoxysilanes such as aminopropyltrimethoxysilane, γ- (2-aminoethyl) aminopropylmethyldimethoxysilane, hexamethyldisilazane, hexaethyldisilazane, hexapropyldisilazane Hexa butyl disilazane, hexa pliers distearate disilazane, hexa hexyl disilazane, hexa cyclohexyl disilazane, hexaphenyl disilazane, divinyl tetramethyl disilazane, include silazanes such as dimethyl tetra-divinyl silazane. Examples of hydrophobizing agents include dimethyl silicone oil, methyl hydrogen silicone oil, methylphenyl silicone oil, alkyl modified silicone oil, chloroalkyl modified silicone oil, chlorophenyl modified silicone oil, fatty acid modified silicone oil, polyether modified Silicone oil, alkoxy-modified silicone oil, carbinol-modified silicone oil, amino-modified silicone oil, fluorine-modified silicone oil, silicone oil such as terminal reactive silicone oil, hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopenta Siloxanes such as siloxane, hexamethyldisiloxane and octamethyltrisiloxane are included. Further, examples of the hydrophobizing agent include fatty acid and metal salts thereof such as undecyl acid, lauric acid, tridecyl acid, dodecyl acid, myristic acid, palmitic acid, pentadecyl acid, stearic acid, heptadecyl acid, arachidic acid, montanic acid Long-chain fatty acids such as oleic acid, linoleic acid and arachidonic acid are included, and metal salts thereof include salts with metals such as zinc, iron, magnesium, aluminum, calcium, sodium and lithium. As the hydrophobizing agent, a silylating agent is most used, and alkoxysilanes and silazanes are preferable because they can be easily treated. In the present embodiment, hexamethyldisilazane and octyltrimethoxysilane are preferred from the viewpoint of reacting with a hydroxyl group present on the surface of the zinc oxide fine particles and being excellent in hydrophobic performance. One type of hydrophobic treatment agent may be used alone, or two or more types may be used in combination. Alternatively, the surface treatment may be performed step by step to achieve the required hydrophobicity depending on the application.

The specific surface area of the zinc oxide fine particles doped with aluminum and hydrophobized and the specific surface area of the zinc oxide fine particles doped with gallium and hydrophobized are both 30 m ² / g or more and 100 m ² / g. The following is preferred. When the specific surface area is less than 30 m ² / g, the primary particle diameter of the fine particles is too large, so that the surface of the toner base particles cannot be effectively covered, and the effect of reducing the environmental difference may not be exhibited. On the other hand, when the specific surface area is more than 100 m ² / g, the particle diameter of the fine particles is too small, so that the fine particles are electrostatically aggregated alone, and the surface of the toner base particles cannot be effectively covered. is there.

  The specific surface area can be measured by the following method. The specific surface area of the zinc oxide fine particles can be measured using Belsorb max (BEL JAPAN INC). Specifically, the specific surface area can be calculated from the BET equation by obtaining the slope A from the nitrogen adsorption amount relative to the relative pressure.

The volume resistivity of the zinc oxide fine particles doped with aluminum and hydrophobized and the volume resistivity of the zinc oxide fine particles treated with gallium and hydrophobized are both 10 Ω · cm or more and 1.0. × 10 ⁷ Ω · cm or less is preferable. When the fixed volume resistivity is less than 10 Ω · cm, the charge amount cannot be maintained, and scattering and fogging may occur. On the other hand, when the volume resistivity is more than 1.0 × 10 ⁷ Ω · cm, excessive charging in the LL environment cannot be suppressed, the development amount is reduced, and the solid image after fixing is static. Electroremovability may also deteriorate.

The volume resistivity was determined by filling 1.0 g of zinc oxide fine particles into an insulating cylindrical container with electrodes having a cross-sectional area of 1.0 cm ² above and below, and obtaining the sample height under a load of 500 g. Is a value obtained by measuring an insulation resistance value and applying a following formula to calculate a volume resistivity from the obtained sample height and insulation resistance value.
Volume resistivity [Ω · cm] = R · (S / t)
(R: Reading value of insulation resistance meter (Ω), applied voltage (100 V) of insulation resistance meter, S: sectional area of sample layer (1 cm ² ), t: thickness of sample layer (cm))

  When the binder resin contains a vinyl resin, the volume-based average particle diameter of the toner base particles is preferably 5.0 μm or more and 8.0 μm or less. When the average particle size is less than 5.0 μm, the cleaning performance may be deteriorated. On the other hand, when the average particle diameter is more than 8.0 μm, the image quality of the formed image may be deteriorated. The average particle size can be controlled by the temperature and time when the particle size grows during the emulsion association. The average particle diameter can be measured and calculated using an apparatus in which a computer system for data processing is connected to “Multisizer 3” (manufactured by Beckman Coulter).

  When the binder resin contains a vinyl resin, the average circularity of the toner base particles is preferably 0.945 or more and 0.980 or less. When the average circularity is less than 0.945, the surface irregularities of the toner base particles become large, and the external additive may not be uniformly dispersed. As a result, the distribution of the charge amount is widened, toner particles are scattered, and fogging may occur. The average circularity can be measured using “FPIA-3000” (manufactured by Sysmex).

  When the binder resin contains a vinyl resin, the water content of the toner base particles is preferably 0.2% by mass or more and 1.8% by mass or less. When the water content is less than 0.2% by mass, the electrostatic peelability of the solid image may deteriorate after the toner image is fixed. When the water content is more than 1.8% by mass, the water is gasified at a time when the toner image is fixed, so that an unfixed toner image immediately before fixing may be disturbed. The water content can be controlled by the amount of magnesium chloride hexahydrate added as the aggregated salt in the emulsion association production method and the drying conditions.

The water content of the toner base particles can be measured using an automatic heat-vaporization moisture measuring system (AQS-724; Hiranuma Sangyo Co., Ltd.). Specifically, 0.5 g of toner base particles left in a 20 ° C./50% RH environment for 24 hours are precisely weighed into a 20 mL glass sample tube, and then sealed with a silicone rubber packing. In order to correct the moisture present in the sealed environment, two empty samples are measured simultaneously. Measurement conditions and reagents are as shown below.
Sample heating temperature: 110 ° C
Sample heating time: 1 minute Nitrogen gas flow rate: 150 ml / min Reagent: HYDRANAL (registered trademark) -Culomat CG-K
HYDRANAL-Coulomat AK

  Moreover, you may contain a titanium oxide as an external additive. The content of titanium oxide is not particularly limited. The content of titanium oxide is preferably 1.0% by mass or less. Titanium oxide is effective from the viewpoint of improving environmental differences.

  The addition amount of the external additive is preferably 0.1% by mass or more and 10.0% by mass or less, and more preferably 1.0% by mass or more and 3.0% by mass or less with respect to the whole toner particles.

[Configuration of two-component developer for developing electrostatic image]
The two-component developer for developing an electrostatic image has the toner particles and carrier particles described above.

  Examples of the carrier particles include magnetic particles made of conventionally known materials such as metals such as iron, ferrite and magnetite, and alloys of these metals with metals such as aluminum and lead. Examples of carrier particles include coated carrier particles having core material particles made of a magnetic material, and a coating material layer covering the surface thereof, and a resin dispersion type in which fine powder of magnetic material is dispersed in a resin. Carrier particles. The carrier particles are preferably coated carrier particles from the viewpoint of suppressing the adhesion of carrier particles to the photoreceptor described later.

  The core particle is, for example, a magnetic material that is strongly magnetized in the direction by a magnetic field. A magnetic body may be used individually by 1 type and may use 2 or more types together. Examples of the magnetic substance include metals exhibiting ferromagnetism such as iron, nickel and cobalt, alloys or compounds containing these metals, and alloys exhibiting ferromagnetism by heat treatment.

Examples of the metal exhibiting ferromagnetism or a compound containing the same include iron, ferrite represented by the following formula (a), and magnetite represented by the following formula (b). M in the formulas (a) and (b) represents one or more monovalent or divalent metals selected from the group consisting of Mn, Fe, Ni, Co, Cu, Mg, Zn, Cd, and Li. Represent.
Formula (a): MO · Fe ₂ O ₃
Formula (b): MFe ₂ O ₄

  Examples of alloys exhibiting ferromagnetism include Heusler alloys such as manganese-copper-aluminum and manganese-copper-tin, and chromium dioxide.

  The core particles are preferably various ferrites. The specific gravity of the coated carrier particles is smaller than the specific gravity of the metal constituting the core particle. Therefore, various ferrites can make the impact force of stirring in the developing device smaller.

  A coating material may be used individually by 1 type, and may use 2 or more types together. As the coating material, a known resin used for coating the core material particles on the carrier particles can be used. The coating material is preferably a resin having a cycloalkyl group from the viewpoint of reducing the moisture adsorbability of the carrier particles and from the viewpoint of increasing the adhesion with the core material particles in the coating layer. Examples of the cycloalkyl group include a cyclohexyl group, a cyclopentyl group, a cyclopropyl group, a cyclobutyl group, a cycloheptyl group, a cyclooctyl group, a cyclononyl group, and a cyclodecyl group. The cycloalkyl group is preferably a cyclohexyl group or a cyclopentyl group, and more preferably a cyclohexyl group from the viewpoint of adhesion between the coating layer and the ferrite particles.

The weight average molecular weight Mw of the resin having a cycloalkyl group is preferably, for example, 10,000 to 800,000, more preferably 100,000 to 750,000. The cycloalkyl group content in the resin is, for example, 10 to 90% by mass. The content of the cycloalkyl group in the resin can be determined by, for example, a known instrumental analysis method such as P-GC / MS or ¹ H-NMR.

  The average particle diameter of the carrier particles is preferably 20 to 100 μm, more preferably 25 to 80 μm in terms of volume-based median diameter. The volume-based median diameter of the carrier particles can be measured by, for example, a laser diffraction particle size distribution measuring apparatus (HELOS; SYMPATEC) equipped with a wet disperser.

  The mixing ratio (mass ratio) of the toner particles and the carrier particles is not particularly limited, but from the viewpoint of chargeability and storage stability, toner particles: carrier particles = 1: 100 to 30: 100 is preferable, and 3: 100 to 20 : 100 is more preferable.

  The size and shape of the toner particles can be appropriately determined within a range in which the effect of the present embodiment can be obtained. For example, the volume average particle diameter of the toner particles is 3.0 to 8.0 μm, and the average circularity of the toner particles is 0.920 to 1.000.

  The number average particle size of the toner particles can be measured and calculated using a device in which a computer system for data processing is connected to “Multisizer 3” (manufactured by Beckman Coulter). Further, the number average particle diameter of the toner particles can be adjusted by, for example, temperature and stirring conditions in the production of the toner particles, classification of the toner particles, mixing of classified toner particles, and the like.

The average circularity of the toner particles is determined by using a flow type particle image analyzer “FPIA-3000” (manufactured by Sysmex), and a perimeter length L1 of a circle having the same projected area as the particle image in a predetermined number of toner particles, It is obtained by dividing the sum of circularity C calculated from the following expression (c) by the predetermined number from the peripheral length L2 of the projected image. The average circularity of the toner particles can be adjusted by, for example, the degree of aging of the resin particles in the production of the toner particles, the heat treatment of the toner particles, the mixing of toner particles having different circularities, and the like.
Formula (c): C = L1 / L2

  Further, the size and shape of the carrier particles can be determined as appropriate within a range in which the effect of the present embodiment can be obtained. For example, the volume average particle diameter of the carrier particles is 15 to 100 μm. The volume average particle diameter of the carrier particles can be measured by a wet method using, for example, a laser diffraction particle size distribution measuring apparatus “HELOS KA” (manufactured by Nippon Laser Corporation). The volume average particle diameter of the carrier particles can be adjusted by, for example, a method for controlling the particle diameter of the core material particles according to the manufacturing conditions of the core material particles, classification of the carrier particles, and mixing of classified products of the carrier particles.

  The toner can be produced, for example, by a method including a step of growing particles produced by aggregating binder resin particles and colorant particles in an aqueous medium.

  This production method may further include a step of dispersing, agglomerating, and fusing the above-described other components in an aqueous medium in an appropriate form. For example, all the manufacturing methods include a step of further dispersing further resin fine particles in which other components such as a colorant are dispersed in the resin component in the aqueous medium, and the additional resin described above for the resin fine particles in the aqueous medium. And a step of agglomerating and fusing the fine particles.

  Further, any of the manufacturing methods may further include an appropriate process according to the form of the toner. For example, any of the production methods may further include one or both of a step of mixing an external additive with toner base particles and a step of mixing toner particles with carrier particles.

  The two-component developer can be produced by mixing an appropriate amount of toner particles and carrier particles. Examples of the mixing apparatus used for the mixing include a Nauter mixer, a W cone, and a V-type mixer.

[Image forming method]
The electrostatic charge image developing two-component developer (electrostatic latent image developing toner) can be applied to an electrophotographic image forming method in the same manner as a normal toner. That is, in the image forming method, an electrophotographic image is formed by fixing an unfixed toner image on a recording medium formed by a two-component developer (electrostatic latent image developing toner) for developing an electrostatic image on the recording medium. In this type of image forming method, the electrostatic charge image developing two-component developer (electrostatic latent image developing toner) of the present embodiment is used as the toner. The image forming method includes, for example, the following steps.

(1) A latent image forming step of forming an electrostatic latent image on the surface of the electrophotographic photosensitive member.
(2) A developing step of developing a toner image by developing the electrostatic latent image formed on the surface of the electrophotographic photosensitive member with a developer carried on the developer carrying member.
(3) A transfer step of transferring the toner image formed on the surface of the electrophotographic photosensitive member to the surface of the recording medium.
(4) A fixing step for thermally fixing the toner image carried on the surface of the recording medium.

  The recording medium is a member for carrying the fixed toner image. As the recording medium, a known medium can be used. Examples thereof include plain paper from thin paper to thick paper, coated printing paper such as high-quality paper, art paper, and coated paper, commercially available Japanese paper and postcard paper. , Plastic films and fabrics for OHP or packaging materials.

  The reason why the effects of the present embodiment can be exhibited by using the two-component developer for electrostatic image development (electrostatic latent image development toner) produced as described above is considered as follows.

  In the present embodiment, surface treatment (hydrophobization treatment) is performed on zinc oxide fine particles doped with aluminum or gallium. The zinc oxide fine particles doped with aluminum or gallium have higher electrical properties as compared with conventional titanium oxide, and leak the charged charge of the toner particles. As a result, the surface resistance was reduced due to the adsorption of the toner, and the charge leakage of the toner in the HH environment was remarkable. In the present embodiment, the surface of the zinc oxide fine particles is subjected to a surface treatment (hydrophobization treatment) to suppress leakage of toner charge due to moisture adsorption in an HH environment, and the hydrophobic treatment agent itself. The electric potential barrier caused by the galvanic oxide suppresses the leakage of electric charges trying to pass inside the zinc oxide fine particles.

  Further, the two-component developer (electrostatic latent image developing toner) for electrostatic image development of the present embodiment is produced by an emulsion association method, and a high-quality image is obtained. It has an appropriate amount of water inside the toner layer of the solid image after fixing. Therefore, since it becomes a path | route of a favorable charge leak with respect to the charged electric charge which causes electrostatic peelability, electrostatic adsorption | suction can be prevented and it has a favorable characteristic. The zinc oxide fine particles in the present embodiment can be used in combination with a two-component developer for electrostatic image development (electrostatic latent image development toner) produced by an emulsion association method, and so far by kneading and pulverization methods and suspension polymerization methods. The electrostatic peelability of a solid image after fixing, which has been a problem of the above, can be improved with a minimum amount of water.

The aforementioned two-component developer for electrostatic image development (electrostatic latent image development toner) contains zinc oxide fine particles surface-treated by doping aluminum or gallium as an external additive.
It is possible to suppress the leakage of the charge of the toner particles due to the adsorption of moisture in the HH environment, and it is also possible to suppress the leakage of the charge trying to pass through the inside of the zinc oxide fine particles. Therefore, the electrostatic charge image developing two-component developer (electrostatic latent image developing toner) of the present embodiment does not cause fogging or scattering even when printing at high speed in a high temperature and high humidity environment. Excellent reproducibility of fine lines and excellent electrostatic peelability during fixing.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited to these Examples.

<Preparation of toner base particle J1>
(Preparation of resin fine particles)
(Preparation of dispersion of resin fine particles [1] for core)
The core resin particles [1] having a multilayer structure were prepared by the first stage polymerization, the second stage polymerization, and the third stage polymerization as follows.

(A) First stage polymerization (Preparation of dispersion of resin fine particles [A1])
In a reaction vessel equipped with a stirrer, a temperature sensor, a cooling tube and a nitrogen introducing device, a surfactant solution in which 4 parts by mass of sodium polyoxyethylene-2-dodecyl ether sulfate was dissolved in 3040 parts by mass of ion-exchanged water was charged. The internal temperature was raised to 80 ° C. while stirring at a stirring speed of 230 rpm under a nitrogen stream. To this surfactant solution, a polymerization initiator solution in which 10 parts by mass of a polymerization initiator (potassium persulfate: KPS) was dissolved in 400 parts by mass of ion-exchanged water was added to a temperature of 75 ° C., and then 532 masses of styrene. A monomer mixture composed of 1 part by weight, 200 parts by weight of n-butyl acrylate, 68 parts by weight of methacrylic acid and 16.4 parts by weight of n-octyl mercaptan was dropped over 1 hour, and this system was kept at 75 ° C. for 2 hours. Polymerization (first stage polymerization) was carried out by heating and stirring to prepare a dispersion of resin fine particles [A1]. The weight average molecular weight (Mw) of the resin fine particles [A1] prepared by the first stage polymerization was 16,500.

(Measurement of weight average molecular weight (Mw))
The weight average molecular weight (Mw) was measured using a high-speed gel permeation chromatography (GPC) apparatus (HLC-8220; Tosoh Corporation) and a column (TSKguardcolumn + TSKgelSuperHZM-M3 series; Tosoh Corporation), and the column temperature was kept at 40 ° C. However, tetrahydrofuran (THF) as a carrier solvent was allowed to flow at a flow rate of 0.2 mL / min, and the sample to be measured was dissolved in THF at a room temperature using a ultrasonic disperser for 5 minutes so that the concentration was 1 mg / mL. Dissolved. Subsequently, it processed with the membrane filter with the pore size of 0.2 micrometer, and obtained the sample solution. 10 μL of this sample solution was injected into the GPC apparatus together with the above carrier solvent, detected using a refractive index detector (RI detector), and the molecular weight distribution of the measurement sample was measured using monodisperse polystyrene standard particles. Calculation was performed using a calibration curve. The standard polystyrene sample for calibration curve measurement has a molecular weight of 6.0 × 10 ² , 2.1 × 10 ³ , 4.0 × 10 ³ , 1.75 × 10 ⁴ , 5.1 × 10 manufactured by Pressure Chemical. ⁴ , 1.1 × 10 ⁵ , 3.9 × 10 ⁶ , 8.6 × 10 ⁵ , 2.0 × 10 ⁶ , 4.48 × 10 ⁶ were used. Ten standard polystyrene samples were measured to prepare a calibration curve. A refractive index detector was used as the detector.

(B) Second stage polymerization (preparation of dispersion of resin fine particles [A2]: formation of intermediate layer)
In a flask equipped with a stirrer, a monomer mixture comprising 101.1 parts by mass of styrene, 62.2 parts by mass of n-butyl acrylate, 12.3 parts by mass of methacrylic acid, and 1.75 parts by mass of n-octyl mercaptan In addition, 93.8 parts by mass of paraffin wax (HNP-57; Nippon Seiwa Co., Ltd.) was added as a release agent, and the mixture was heated to 90 ° C. and dissolved. A surfactant solution in which 3 parts by mass of sodium polyoxyethylene-2-dodecyl ether sulfate was dissolved in 1560 parts by mass of ion-exchanged water was heated to 98 ° C. To this surfactant solution, 32.8 parts by mass (in terms of solid content) of the above-mentioned dispersion of resin fine particles [A1] was added, and a mechanical disperser having a circulation path (CLEAMIX (registered trademark); M Technique Co., Ltd.) The monomer solution containing the paraffin wax was mixed and dispersed for 8 hours to prepare a dispersion liquid containing emulsified particles having a dispersed particle diameter of 340 nm. Next, a polymerization initiator solution in which 6 parts by mass of potassium persulfate is dissolved in 200 parts by mass of ion-exchanged water is added to this emulsified particle dispersion, and polymerization is performed by heating and stirring at 98 ° C. for 12 hours (second stage polymerization). ) To prepare a dispersion of resin fine particles [A2]. The weight average molecular weight (Mw) of the resin fine particles [A2] prepared by the second stage polymerization was 23000.

(C) Third stage polymerization (preparation of dispersion of resin fine particles [1] for core part: formation of outer layer)
A polymerization initiator solution prepared by dissolving 5.45 parts by mass of potassium persulfate in 220 parts by mass of ion-exchanged water is added to the resin particle [A2], and 293.8 parts by mass of styrene and 154.1 parts by mass of n-butyl acrylate. , N-octyl mercaptan 7.08 parts by mass of a monomer mixture was added dropwise at 80 ° C. over 1 hour. After completion of the dropping, the mixture was heated and stirred for 2 hours for polymerization (third stage polymerization), and then cooled to 28 ° C. to obtain a dispersion of resin fine particles for core [1]. In addition, the weight average molecular weight (Mw) of the resin fine particles for core [1] was 26800. Moreover, the volume-based average particle diameter of the resin fine particles [1] for core part was 125 nm. The glass transition temperature (Tg) of the resin fine particles for core part [1] was 30.5 ° C. The volume-based average particle size was measured using a particle size distribution measuring device (Coulter Multisizer 3; Beckman Coulter, Inc.).

(Preparation of dispersion of resin fine particles [1] for shell layer)
Except for using a monomer mixture in which styrene was changed to 548 parts by mass, 2-ethylhexyl acrylate to 156 parts by mass, methacrylic acid to 96 parts by mass, and n-octyl mercaptan to 16.5 parts by mass, the core part A dispersion of resin fine particles for shell layer [1] was prepared in the same manner as in the first-stage polymerization in the preparation of dispersion for resin fine particles [1]. The weight average molecular weight (Mw) of the resin particles for shell layer [1] was 26800. The Tg of the resin particles [1] for shell layer was 49.8 ° C.

(Preparation of colorant fine particle dispersion [1])
90 parts by mass of sodium dodecyl sulfate was added to 1600 parts by mass of ion-exchanged water, and 420 parts by mass of carbon black (Regal 330R; manufactured by Cabot) was gradually added while stirring the solution. Next, a colorant fine particle dispersion [1] in which colorant fine particles are dispersed was prepared by performing a dispersion treatment using a mechanical disperser (CLEAMIX; M Technique Co., Ltd.). The volume-based median diameter of the colorant fine particles in the colorant fine particle dispersion [1] measured with an electrophoretic light scattering photometer (ELS-800; Otsuka Electronics Co., Ltd.) was 110 nm.

(Formation of core part (core particle))
420 parts by mass (in terms of solid content) of dispersion of resin fine particles [1] for core, 900 parts by mass of ion-exchanged water, and 100 parts by mass of colorant fine particle dispersion [1] are added to a temperature sensor, a cooling tube, and nitrogen. The mixture was stirred in a reaction vessel equipped with an introduction device and a stirring device. After adjusting the temperature in the reaction vessel to 30 ° C., 5 mol / L sodium hydroxide aqueous solution was added to this solution to adjust the pH to 8-11.

  Next, an aqueous solution in which 60 parts by mass of magnesium chloride hexahydrate was dissolved in 60 parts by mass of ion-exchanged water as a flocculant containing Mg element was added at 30 ° C. over 10 minutes with stirring. After standing for 3 minutes, the heating was started, and the system was heated to 80 ° C. (core formation temperature) over 80 minutes. In this state, the particle diameter of the particles is measured with a flow particle image analyzer (FPIA2100; Sysmex Corporation), and the volume-based average particle diameter (hereinafter also referred to as “target particle diameter of core particles”) is 5. When the particle size reached 2 μm, an aqueous solution in which 40.2 parts by mass of sodium chloride was dissolved in 1000 parts by mass of ion-exchanged water was added to stop particle size growth. Next, as a ripening treatment, the fusion was continued by heating and stirring at a liquid temperature of 80 ° C. (core ripening temperature) for 1 hour to form a core part (core particle) [1]. In addition, the average circularity of the core part (core particle) [1] measured by a flow type particle image analyzer (FPIA2100; Sysmex Corporation) was 0.952.

(Formation of shell layer)
Subsequently, 46.8 parts by mass (in terms of solid content) of a dispersion of resin fine particles for shell layer [1] is added at 65 ° C., and 2 parts by mass of magnesium chloride hexahydrate is added as an aggregating agent containing Mg element. After adding an aqueous solution dissolved in 60 parts by mass of exchange water over 10 minutes, the temperature was raised to 80 ° C. (shell formation temperature), and stirring was continued for 1 hour to obtain the surface of the core (core particle) [1]. Then, after the fine particles of the resin fine particles [1] for the shell layer were fused, an aging treatment was performed to a predetermined circularity at 80 ° C. (shell aging temperature) to form a shell layer. Here, an aqueous solution in which 40.2 parts by mass of sodium chloride was dissolved in 1000 parts by mass of ion-exchanged water was added, and the mixture was cooled to 30 ° C. at 8 ° C./min. The toner base particles J1 having a shell layer on the surface of the core (core particles) were prepared by repeatedly washing with exchanged water and then drying with hot air at 40 ° C.

<Preparation of toner base particles J2 to J6, J13 to J23 and H1 and H2>
In the production of the toner base particles J1, the toner base particles J1 are changed except that the target particle diameter of the core particles, the average circularity of the core particles, the amount of magnesium chloride hexahydrate added, and the drying conditions are appropriately changed. In the same manner, toner base particles J2 to J6, J13 to J23, and H1 and H2 were produced, respectively.

<Preparation of toner base particles J7 to J9>
(Preparation of PEs shell resin fine particle dispersion)
(Synthesis of shell resin (styrene-acrylic modified polyester resin))
In a 10-liter four-necked flask equipped with a nitrogen inlet tube, a dehydrating tube, a stirrer and a thermocouple, 500 parts by mass of bisphenol A propylene oxide 2 mol adduct, 117 parts by mass of terephthalic acid, 82 parts by mass of fumaric acid and ester Then, 2 parts by mass of a catalyst for oxidation (tin octoate) was added and subjected to a condensation polymerization reaction at 230 ° C. for 8 hours, further reacted at 8 kPa for 1 hour, and cooled to 160 ° C.

  A mixture of 10 parts by mass of acrylic acid, 30 parts by mass of styrene, 7 parts by mass of butyl acrylate, and 10 parts by mass of a polymerization initiator (di-t-butyl peroxide) was added dropwise over 1 hour using a dropping funnel. The styrene-acrylic modified polyester resin was removed by continuing acrylic acid, styrene, and butyl acrylate after the addition polymerization reaction was continued for 1 hour while the temperature was maintained, followed by heating to 200 ° C. and holding at 10 kPa for 1 hour. [1] was prepared. The prepared styrene-acryl-modified polyester resin [1] had a glass transition point of 60 ° C. and a softening point of 105 ° C.

(Preparation of PEs shell resin fine particle dispersion)
100 parts by mass of the obtained styrene-acryl-modified polyester resin [1] was pulverized with an RM type Landel mill (Tokuju Kogyo Co., Ltd.), and 638 parts by mass of a 0.26% by mass sodium lauryl sulfate solution prepared in advance. While mixing and stirring, an ultrasonic homogenizer (US-150T; Nippon Seiki Seisakusho Co., Ltd.) is used for ultrasonic dispersion for 30 minutes at V-LEVEL, 300 μA, and PEs shell resin fine particles having a volume-based median diameter of 250 nm [ A dispersion liquid of PEs shell resin fine particles [S1] in which S1] is dispersed was prepared.

  In the formation of the shell layer (b), toner base particles J7 were prepared in the same manner as the toner base particles J1, except that a PEs shell resin fine particle dispersion was used instead of the shell layer resin fine particles [1]. .

  The toner base particles J8 are the same as the toner base particles J7, except that the target particle diameter of the core particles, the average circularity of the core particles, the amount of magnesium chloride hexahydrate added, and the drying conditions are appropriately changed. , J9 was produced.

<Preparation of toner base particles J10 to J12>
(Preparation of amorphous resin fine particle dispersion (A1))
(First stage polymerization)
A reaction vessel equipped with a stirrer, a temperature sensor, a cooling pipe and a nitrogen introduction device was charged with 4 parts by mass of polyoxyethylene (2) sodium dodecyl ether sulfate and 3000 parts by mass of ion-exchanged water, and stirred at a rate of 230 rpm under a nitrogen stream. The internal temperature was raised to 80 ° C. while stirring. After raising the temperature, 10 parts by mass of potassium persulfate dissolved in 200 parts by mass of ion-exchanged water is added to obtain a liquid temperature of 75 ° C., 584 parts by mass of styrene, 160 parts by mass of n-butyl acrylate, 56 parts by mass of methacrylic acid. After the monomer mixed solution composed of parts was added dropwise over 1 hour, polymerization was performed while heating and stirring at 75 ° C. for 2 hours to prepare a dispersion of binder resin fine particles [a1].

(Second stage polymerization)
A reaction vessel equipped with a stirrer, a temperature sensor, a condenser, and a nitrogen introducing device was charged with a solution prepared by dissolving 2 parts by mass of polyoxyethylene (2) sodium dodecyl ether sulfate in 3000 parts by mass of ion-exchanged water, and brought to 80 ° C. After heating, 42 parts by weight of the above binder resin fine particles [a1] (in terms of solid content) and 70 parts by weight of microcrystalline wax (HNP-0190; Nippon Seiwa Co., Ltd.) were added to 239 parts by weight of styrene and n-butyl acrylate. A mechanical disperser having a circulation path (Clearmix; M.M.) was added to a monomer solution consisting of 111 parts by mass, 26 parts by mass of methacrylic acid, and 3 parts by mass of n-octyl mercaptan. By Technic Co., Ltd., a dispersion containing emulsified particles (oil droplets) was prepared by mixing and dispersing for 1 hour.

  Next, an initiator solution in which 5 parts by mass of potassium persulfate is dissolved in 100 parts by mass of ion-exchanged water is added to this dispersion, and this system is heated and stirred at 80 ° C. for 1 hour to perform polymerization. A dispersion of binder resin fine particles [a2] was prepared.

(3rd stage polymerization)
A solution prepared by dissolving 10 parts by mass of potassium persulfate in 200 parts by mass of ion-exchanged water is further added to the above dispersion of the binder resin fine particles [a2], and 380 parts by mass of styrene under a temperature condition of 80 ° C. A monomer mixed solution consisting of 132 parts by mass of n-butyl acrylate, 39 parts by mass of methacrylic acid, and 6 parts by mass of n-octyl mercaptan was added dropwise over 1 hour. After completion of dropping, polymerization is performed by heating and stirring for 2 hours, and then cooled to 28 ° C., whereby amorphous resin fine particles which are dispersions of vinyl resin (second resin) fine particles having acid groups A dispersion (A1) was obtained.

(Preparation of crystalline resin)
(Synthesis of crystalline resin (C1))
274 parts by mass of sebacic acid (molecular weight 202.25) as the polyvalent carboxylic acid compound of the material of the crystalline polyester polymer segment (first resin segment) and 1,12-dodecanediol (molecular weight as the polyhydric alcohol compound) 202.33) 274 parts by mass were placed in a reaction vessel equipped with a nitrogen introduction tube, a dehydration tube, a stirrer and a thermocouple, heated to 160 ° C. and dissolved. 23 parts by mass of styrene, 6 parts by mass of n-butyl acrylate, 4 parts by mass of dicumyl peroxide, and acrylic as a bireactive monomer, which are materials for the premixed vinyl polymer segment (second resin segment) A solution of 2 parts by mass of acid was added dropwise with a dropping funnel over 1 hour. Stirring was continued for 1 hour while maintaining at 170 ° C., and after polymerizing styrene, n-butyl acrylate and acrylic acid, 2.5 parts by mass of tin (II) 2-ethylhexanoate, 0.2 parts by mass of gallic acid The mixture was heated to 210 ° C. and reacted for 8 hours. Furthermore, reaction was performed at 8.3 kPa for 1 hour to obtain a crystalline resin (C1) which is a hybrid crystalline polyester resin in which the first resin and the second resin are chemically bonded.

(Preparation of crystalline resin fine particle dispersion 1)
30 parts by mass of the crystalline resin (C1) in a molten state was transferred at a transfer rate of 100 parts by mass / min to an emulsifying disperser (Cabitron CD1010; Eurotech Co., Ltd.). Simultaneously with the transfer of the molten crystalline resin (C1), the emulsifier / disperser is diluted with 70 parts by mass of reagent ammonia water with ion-exchanged water in an aqueous solvent tank at a concentration of 0.37% by mass. Ammonia water was transferred at a transfer rate of 0.1 L / min while being heated to 100 ° C. with a heat exchanger. Then, by operating this emulsification disperser under the conditions of a rotor rotation speed of 60 Hz and a pressure of 5 kg / cm ² , a crystalline resin fine particle dispersion 1 having a volume-based median diameter of 200 nm and a solid content of 30 parts by mass. Was prepared.

(Aggregation / fusion process)
In a reaction vessel equipped with a stirrer, a temperature sensor, a cooling tube, and a nitrogen introducing device, 300 parts by mass of the amorphous resin fine particle dispersion (A1) (in terms of solid content) and the dispersion 60 of the crystalline resin fine particle dispersion 1 are obtained. After 5 parts by weight (in terms of solid content), 1100 parts by weight of ion-exchanged water, and 40 parts by weight of colorant fine particle dispersion [Bk] (in terms of solid content) were adjusted to 30 ° C., 5N water The pH was adjusted to 10 by adding an aqueous sodium oxide solution. Next, an aqueous solution obtained by dissolving 60 parts by mass of magnesium chloride hexahydrate in 60 parts by mass of ion-exchanged water was added over 10 minutes at 30 ° C. with stirring. The temperature was raised after holding for 3 minutes, and the temperature of the system was raised to 85 ° C. over 60 minutes, agglomerating while maintaining 85 ° C., and the particle growth reaction was continued. In this state, the particle size of the agglomerated particles is measured with a particle size distribution analyzer (Coulter Multisizer 3; Beckman Coulter, Inc.), and when the volume-based median diameter becomes 6.6 μm (target particle of core particle) By adding an aqueous solution in which 40 parts by mass of sodium chloride is dissolved in 160 parts by mass of ion-exchanged water, the particle growth is stopped, and further, the mixture is heated and stirred at a liquid temperature of 80 ° C. for 1 hour as an aging step. By fusing the particles, a dispersion of toner base particles J10 was prepared. The final particle size was 6.2 μm.

(Washing / drying process)
The produced toner base particles J-10 were subjected to solid-liquid separation with a basket type centrifuge (MARK III, 60 × 40 + M; Matsumoto Kikai Co., Ltd.) to form a wet cake of toner base particles J-10. The wet cake was washed with ion exchange water at 40 ° C. until the electric conductivity of the filtrate reached 5 μS / cm with the basket-type centrifuge, and then transferred to a dryer (flash jet dryer; Seishin Corporation). Then, toner base particles J10 were produced by drying until the water content reached 0.5% by mass.

  The toner base particle J11 is the same as the toner base particle J10 except that the target particle diameter of the core particle, the average circularity of the core particle, the amount of magnesium chloride hexahydrate added, and the drying conditions are appropriately changed. , J12 was produced.

<Preparation of toner base particles H3>
100 parts by mass of a polyester resin (binder resin, melting temperature (110 ° C.)) obtained by polycondensation using bisphenol A propylene oxide, terephthalic acid and trimellitic anhydride as monomers, and carbon black (Regal 330R; Cabot) Henschel mixer) 5.0 parts by weight, 2.0 parts by weight of a charge control agent (Bontron E84; Orient Chemical Co., Ltd.) which is a zinc compound of salicylic acid, and 4.5 parts by weight of paraffin wax as a release agent (Mitsui Mining Co., Ltd.) was mixed uniformly for 10 minutes to obtain a mixture. This mixture was kneaded while being heated to 105 ° C. with a twin-screw extruder and cooled to obtain a kneaded product. The obtained kneaded material was coarsely pulverized with a cutting mill, then finely pulverized with an ultrasonic jet mill, and classified so as to remove fine powder with a classifier, thereby preparing toner base particles H3.

<Preparation of conductive zinc oxide powder 1>
150 g of zinc oxide powder having an average particle diameter of 1.0 μm produced by the French method was added to 2800 mL of distilled water at a temperature of 20 ° C. and dispersed. 75 g of ammonium bicarbonate was dissolved in 500 mL of water at a temperature of 20 ° C., an aqueous ammonium bicarbonate solution was added to the zinc oxide dispersion, stirred at the same temperature for 30 minutes, and then 70 ° C. at a rate of 1 ° C./min. The temperature was raised to 0 ° C. to produce basic zinc carbonate. A basic zinc carbonate crystal was grown by aging at the same temperature for 30 minutes. Next, 14.3 g of aluminum sulfate was dissolved in 500 mL of distilled water, added to the obtained basic zinc carbonate aqueous dispersion, stirred and dispersed for 30 minutes, and then the temperature of the solution was raised to 70 ° C. again. And then aged again for 30 minutes. After aging, the dispersion is subjected to suction filtration, the solid matter is collected by filtration and dried at 150 ° C. or lower, calcined at 300 ° C. for 3 hours, and further reduced and fired at 400 ° C. for 2 hours in a hydrogen atmosphere. Conductive zinc oxide powder 1 was obtained by crushing with a pulverizer. The specific surface area of the obtained conductive zinc oxide powder 1 by the BET method was 54.3 m ² / g.

<Preparation of conductive zinc oxide powder 2>
A conductive zinc oxide powder 2 was obtained in the same manner as the conductive zinc oxide powder 1 except that it was calcined at 300 ° C. for 3 hours and further reduced and fired at 800 ° C. for 2 hours in a hydrogen atmosphere. The specific surface area by the BET method of the obtained conductive zinc oxide powder 2 was 29.1 m ² / g.

<Preparation of conductive zinc oxide powder 3>
A conductive zinc oxide powder 3 was obtained in the same manner as the conductive zinc oxide powder 1 except that it was calcined at 300 ° C. for 3 hours and further reduced and fired at 380 ° C. for 4 hours in a hydrogen atmosphere. The specific surface area of the obtained conductive zinc oxide powder 3 according to the BET method was 110.8 m ² / g.

<Preparation of conductive zinc oxide powder 4>
A conductive zinc oxide powder 4 was obtained in the same manner as the conductive zinc oxide powder 1 except that the dissolved aluminum sulfate was changed to 21.5 g. The specific surface area of the obtained conductive zinc oxide powder 4 by the BET method was 58.3 m ² / g.

<Preparation of conductive zinc oxide powder 5>
A conductive zinc oxide powder 5 was obtained in the same manner as the conductive zinc oxide powder 1 except that the dissolved aluminum sulfate was changed to 7.5 g. The specific surface area by the BET method of the obtained conductive zinc oxide powder 5 was 59.2 m ² / g.

<Preparation of conductive zinc oxide powder 6>
150 g of zinc oxide was dispersed in 2800 mL of distilled water at a temperature of 20 ° C. 75 g of ammonium bicarbonate was dissolved in 500 mL of water at a temperature of 20 ° C., this aqueous ammonium bicarbonate solution was added to the zinc oxide dispersion, stirred at the same temperature for 30 minutes, and then 70 ° C. at a rate of 1 ° C./min. The temperature was raised to 0 ° C. to produce basic zinc carbonate. A basic zinc carbonate crystal was grown by aging at the same temperature for 30 minutes. Next, 1.9 g of gallium chloride is dissolved in 500 mL of distilled water, added to the aqueous dispersion of basic zinc carbonate obtained above, dispersed by stirring for 30 minutes, and then the temperature of the solution is raised to 70 ° C. again. Then, it was aged again for 30 minutes. Next, the dispersion is suction filtered and dried, and the dried product is calcined at 300 ° C. for 3 hours, subsequently reduced and fired at 400 ° C. for 2 hours in a hydrogen atmosphere, and pulverized with a pulverizer to form conductive zinc oxide powder. 6 was obtained. The specific surface area of the obtained conductive zinc oxide powder 6 according to the BET method was 73.6 m ² / g.

<Preparation of conductive zinc oxide powder 7>
Zinc powder (1000 g / h, particle size ≦ 5 μm) was transferred to the evaporation step by a stream of nitrogen (2.5 m ³ / h). In this step, evaporation was performed using a hydrogen / air flame (hydrogen: 4.78 m ³ / h, air: 10.30 m ³ / h, lambda = 0.9). Zinc vapor, hydrogen, nitrogen and thereafter the reaction mixture of water, nitrogen ^2m 3 / h was controlled to a temperature of 850 ° C. by the metering, and 10 wt% aqueous solution of aluminum chloride _{(AlCl 3 · 6H 2 O)} 300g / H was supplied in the form of an aerosol. The oxidation process, the addition of air ^3m 3 / h and the cooling gas ^{20 m} 3 / h, was allowed to control the reaction temperature to about 530 ° C.. Conductive zinc oxide powder 7 was obtained by separating the doped zinc oxide powder from the gas stream with a mesh. The specific surface area of the obtained conductive zinc oxide powder 7 according to the BET method was 85.6 m ² / g.

<Preparation of conductive zinc oxide powder 8>
A conductive zinc oxide powder 8 was obtained in the same manner as the conductive zinc oxide powder 1 except that no dissolved aluminum sulfate was added. The specific surface area of the obtained conductive zinc oxide powder 8 by the BET method was 59.3 m ² / g.

<Preparation of zinc oxide fine particles J1>
Using a commercially available powder sputtering apparatus (Kyoritsu Co., Ltd.), the surface of each conductive zinc oxide powder was subjected to radio frequency (RF) sputtering surface treatment with ZnO. 100 g of conductive zinc oxide powder 1 doped with aluminum was put into a powder sputtering apparatus. Using a Zn target with a purity of 99.9%, first, the conductive zinc oxide powder 1 is heated to 120 ° C., and the pressure is reduced to a vacuum level at which plasma appears using only Ar gas. The powder surface was cleaned (etching treatment) for 30 minutes. Thereafter, oxygen was introduced while slowly stirring the powder, and in addition to the 400 W RF power, a DC component of 240 V was also added, and the fine particles were treated for 1 hour. By this method, zinc oxide fine particles J1 subjected to surface treatment for forming a higher resistance layer composed of only ZnO on the surface of the conductive zinc oxide powder 1 doped with aluminum were obtained. The volume resistivity of the obtained zinc oxide fine particles J1 was 1.62 × 10 ² Ω · cm, and the specific surface area by the BET method was 32.3 m ² / g.

<Preparation of zinc oxide fine particles J2 and J3>
Zinc oxide fine particles J2 and zinc oxide fine particles J3 were obtained in the same manner as the zinc oxide fine particles J1, except that the conductive zinc oxide powder was changed to the conductive zinc oxide powders 7 and 6, respectively.

<Preparation of zinc oxide fine particles J4>
100 parts by weight of conductive zinc oxide powder 1 is put in a mixer, sprayed with 0.5 parts by weight of water and 10 parts by weight of hexamethyldisilazane with stirring in a nitrogen atmosphere, heated at 260 ° C. for 80 minutes, and then cooled. Was subjected to surface treatment to obtain zinc oxide fine particles J4. The obtained zinc oxide fine particles J4 had a volume resistivity of 1.63 × 10 ⁵ Ω · cm, and a specific surface area by the BET method of 53.2 m ² / g.

<Preparation of zinc oxide fine particles J5>
Zinc oxide fine particles J5 were obtained in the same manner as the zinc oxide fine particles J4 except that the hexamethyldisilazane was changed to 15 parts by mass and the conductive zinc oxide powder was changed to the conductive zinc oxide powder 7.

<Preparation of zinc oxide fine particles J6>
Zinc oxide fine particles J6 were obtained in the same manner as the zinc oxide fine particles J4 except that the hexamethyldisilazane was changed to 12 parts by mass and the conductive zinc oxide powder was changed to the conductive zinc oxide powder 6.

<Preparation of zinc oxide fine particles J7>
100 parts by weight of conductive zinc oxide powder 1 is put in a mixer, sprayed with 0.5 parts by weight of water and 10 parts by weight of octyltrimethoxysilane while stirring in a nitrogen atmosphere, heated at 260 ° C. for 80 minutes, and then cooled. Was subjected to surface treatment to obtain zinc oxide fine particles J7. The obtained zinc oxide fine particles J7 had a volume resistivity of 1.09 × 10 ⁶ Ω · cm, and a specific surface area by the BET method of 30.6 m ² / g.

<Production of zinc oxide fine particles J8>
Zinc oxide fine particles J8 were obtained in the same manner as the zinc oxide fine particles J7 except that the hexamethyldisilazane was changed to 15 parts by mass and the conductive zinc oxide powder was changed to the conductive zinc oxide powder 7.

<Preparation of zinc oxide fine particles J9>
Zinc oxide fine particles J9 were obtained in the same manner as the zinc oxide fine particles J7 except that the hexamethyldisilazane was changed to 12 parts by mass and the conductive zinc oxide powder was changed to the conductive zinc oxide powder 6.

<Preparation of zinc oxide fine particles J10>
100 parts by mass of zinc oxide fine particles 1 were put into a mixer, and the powder was put into a fluid state by stirring under a nitrogen atmosphere. As dimethyl silicone, 5 parts by mass of dimethylpolysiloxane, which is a non-reactive silicone oil, was sprayed. While stirring was continued, the temperature was raised from room temperature to 340 ° C., where it was maintained for 30 minutes, and then this was cooled to perform surface treatment. By this treatment, the volume resistivity was 2.66 × 10 ² Ω · cm, and the surface-treated zinc oxide fine particles J10 having a specific surface area of 34.0 m ² / g by BET method were obtained.

<Preparation of zinc oxide fine particles J11>
Zinc oxide fine particles J11 were obtained in the same manner as the zinc oxide fine particles J10 except that hexamethyldisilazane was changed to 10 parts by mass and the conductive zinc oxide powder was changed to the conductive zinc oxide powder 7.

<Preparation of zinc oxide fine particles J12>
Zinc oxide fine particles J12 were obtained in the same manner as the zinc oxide fine particles J10 except that hexamethyldisilazane was changed to 6 parts by mass and the conductive zinc oxide powder was changed to the conductive zinc oxide powder 6.

<Preparation of zinc oxide fine particles J13>
Zinc oxide fine particles J13 were obtained in the same manner as the zinc oxide fine particles J7, except that hexamethyldisilazane was used and the conductive zinc oxide powder was changed to the conductive zinc oxide powder 2.

<Preparation of zinc oxide fine particles J14>
Zinc oxide fine particles J14 were obtained in the same manner as the zinc oxide fine particles J7 except that the hexamethyldisilazane was changed to 15 parts by mass and the conductive zinc oxide powder was changed to the conductive zinc oxide powder 3.

<Preparation of zinc oxide fine particles J15>
Zinc oxide fine particles J15 were obtained in the same manner as the zinc oxide fine particles J7 except that hexamethyldisilazane was used and the conductive zinc oxide powder was changed to the conductive zinc oxide powder 4.

<Preparation of zinc oxide fine particles J16>
Zinc oxide fine particles J16 were obtained in the same manner as the zinc oxide fine particles J7 except that hexamethyldisilazane was used and the conductive zinc oxide powder was changed to the conductive zinc oxide powder 5.

<Preparation of Zinc Oxide Fine Particles J17-J23>
The zinc oxide fine particles J4 were directly used as zinc oxide fine particles J17 to J23.

Preparation of Zinc Oxide Fine Particles H1 to H3 for Comparative Example <Preparation of Zinc Oxide Fine Particle H1>
Zinc oxide fine particles H1 were obtained in the same manner as the zinc oxide fine particles J4 except that the conductive zinc oxide powder 8 which was undoped zinc oxide was used and the hexamethyldisilazane was changed to 10 parts by mass.

<Preparation of zinc oxide fine particles H2 and H3>
The conductive zinc oxide powder 1 was not subjected to surface treatment, and was directly used as H2 and H3 zinc oxide fine particles.

<Measurement of volume resistivity of zinc oxide fine particles>
The volume resistivity of zinc oxide fine particles was determined by filling 1.0 g of zinc oxide fine particles into an insulating cylindrical container with electrodes having a cross-sectional area of 1.0 cm ² above and below, and obtaining the sample height under a load of 500 g. This is a value obtained by measuring the insulation resistance value by applying an electric field of DC 100 V and calculating the volume resistivity by the following formula from the obtained sample height and insulation resistance value.
Volume resistivity [Ω · cm] = R · (S / t)
R: Insulation resistance reading (Ω)
Insulation resistance meter applied voltage (100V)
S: sectional area of sample layer (1 cm ² )
t: thickness of sample layer (cm)

<Measurement of specific surface area of zinc oxide fine particles>
The specific surface area of the zinc oxide fine particles was measured using Belsorb max (BEL JAPAN INC). Specifically, the specific surface area was calculated from the BET equation by obtaining the slope A from the nitrogen adsorption amount relative to the relative pressure.

<Production of Toners J1, J4, J7, J10, J13 to J16, J18 to J23, and H1 to H3>
To 100 parts by mass of each toner base particle, 0.5 parts by mass of zinc oxide fine particles and 1.0 part by mass of silica fine particles (RX-200, Degussa Japan Co., Ltd.) having a primary average particle diameter of 12 nm are added, and a Henschel mixer is added. (FM10B; Mitsui Miike Chemical Co., Ltd.), mixing with a stirring blade peripheral speed of 40 m / sec and a processing temperature of 30 ° C. for 12 minutes, toners J1, J4, J7, J10, J13 to J16, J18 to J23, H1 to H3 were prepared.

<Preparation of Toners J2, J3, J5, J6, J8, J9, J11, J12, J17>
Toners J2, J3, J5, and J6 are the same as toner J1 except that titanium dioxide (HMDS treatment, hydrophobization degree 55%, number average primary particle size: 20 nm) is further added in a predetermined amount shown in Table 2. , J8, J9, J11, J12, and J17 were produced.

<Preparation of two-component developers J1 to J23, H1 to H3>
As a carrier, a ferrite carrier having a volume average particle diameter of 30 μm coated with a copolymer resin of cyclohexyl methacrylate and methyl methacrylate (monomer mass ratio = 1: 1) was prepared. Next, each toner was mixed at a blending ratio of 6 parts by weight of toner with respect to 100 parts by weight of carrier, and then sieved with a mesh having a mesh size of 125 μm to produce a two-component developer. The mixing treatment was performed in a normal temperature and normal humidity (temperature 20 ° C., relative humidity 50% RH) environment using a V blender (rotation speed 20 rpm, stirring time 20 minutes).

  Tables 1 and 2 show the constituent elements and the physical property values of the toner base particles. In addition, No. Is a number common to zinc oxide fine particles, toner base particles, toner and two-component developer.

<Evaluation>
A commercially available digital color printer “bizhub (registered trademark) C554; Konica Minolta Business Technologies Co., Ltd.) was used as an evaluation machine.Each two-component developer was put into this evaluation machine and the environment was 20 ° C./50% RH. In addition, 20,000 sheets were printed, and in addition, 20,000 sheets were printed in each of the HH, LL, and NN environments for a total of 80,000 sheets, and the following items were evaluated.

<Measurement of average charge>
The average charge amount was measured using the apparatus shown in FIG. First, 1 g of each two-component developer weighed with a precision balance was placed on the entire surface of the conductive sleeve 61 so as to be uniform. In addition, a voltage of 2 kV was supplied from the bias power source 63 to the conductive sleeve 61, and the rotation speed of the magnet roll 62 provided in the conductive sleeve 61 was set to 1000 rpm. The two-component developer was collected on the cylindrical electrode 64 by being left for 30 seconds under this condition. After 30 seconds, the potential Vm of the cylindrical electrode 64 is read, and the charge amount of the two-component developer is obtained. The mass of the collected two-component developer is measured with a precision balance, and the average charge amount (−μC / g )

<Evaluation of image density>
The image density of the solid image portion was measured using a reflection densitometer (RD-918; Macbeth), and evaluated according to the following criteria. If the density of the solid image portion is 1.20 or more, there is no practical problem, but if it is less than 0.80, the practical use is severe.
A: 1.30 or more B: 1.20 or more, less than 1.30 C: less than 1.20

<Evaluation of gabri concentration>
The fog density was measured using a reflection densitometer (RD-918; Macbeth), and evaluated according to the following criteria. Here, the “fog density” means the density (white paper density) of printing paper that has not been printed at 20 locations, and the average value is the white paper density. Next, the density of the white background portion of the printing paper on which the plain image is printed. Is a value obtained by subtracting the white paper density from the average value. If the fog density is less than 0.015, there is no practical problem, but if it is 0.015 or more, the practical use is severe.
A: Less than 0.005 B: 0.005 or more, less than 0.015 C: 0.015 or more

<Evaluation of fine line reproducibility>
In the state after printing 80,000 sheets, an MTF chart having a line width of 100 μm was output, and fine line reproducibility was visually observed from a monitor image enlarged 100 times, and evaluated according to the following criteria.
A: Dust due to two-component developer, good reproducibility without fine lines, good reproducibility B: Minor dust and repelling confirmed but no problem in practical use ×: Dust and repellency occurred strongly, causing practical problems

<Evaluation of electrostatic peelability>
After printing 80,000 sheets, 100 solid sheets were printed continuously, an MTF chart with a line width of 100 μm was output, and the fine line reproducibility was visually observed from a monitor image enlarged 100 times, and evaluated according to the following criteria.
◎: 100 sheets can be easily separated ○: Although there is a slight catch, there is no practical problem ×: Cannot be separated easily, there is a practical problem

<Evaluation of environmental difference in average charge amount>
The environmental difference (μC / g) in the average charge amount was an absolute value of the difference between the LL charge amount and the HH charge amount. Moreover, the environmental difference of the average charge amount was evaluated according to the following evaluation criteria. In this example, “◎” or “◯” was regarded as acceptable.
A: Environmental difference in average charge amount is less than 3 μC / g ○: Environmental difference in average charge amount is 3-6 μC / g
×: Environmental difference in average charge exceeds 6 μC / g

<Comprehensive evaluation>
The overall evaluation was based on the following criteria.
◎: Fine line reproducibility, electrostatic peelability and average charge amount are all ◎: Fine line reproducibility, electrostatic peelability and average charge amount environment difference are ◯ ×: Fine line reproduction In this case, the number of x was described as a result.

  The evaluation results of each evaluation are shown in Tables 3-5.

  As shown in Tables 3 to 5, the electrostatic charge image developing two-component developers J1 to J23 containing zinc oxide fine particles doped with aluminum or gallium as an external additive and surface-treated with a surface treating agent can be used in any environment. Even below, it was excellent in charge amount, image density and fog. Moreover, it was excellent in fine line reproducibility and electrostatic peelability.

  On the other hand, in the two-component developer H1 for developing an electrostatic charge image that has been surface-treated without doping aluminum or gallium, the electrostatic peelability is not sufficient. This is considered to be because the charge charged in the toner particles could not be leaked. Further, the two-component developer H2 for developing an electrostatic charge image doped with aluminum and not subjected to surface treatment had insufficient fine line reproducibility. This is presumably because the adsorbed water molecules lower the surface resistance value of the toner base particles and further promote charge leakage of the toner base particles. Further, the electrostatic charge image developing two-component developer H3 doped with aluminum and not surface-treated has insufficient electrostatic releasability and fine line reproducibility. The reason is considered as described above.

  The electrostatic latent image developing toner and the image formed by the image forming method using the electrostatic latent image developing toner according to the present invention have good color stability and high quality. Therefore, according to the present invention, further popularization in an electrophotographic image forming method is expected.

61 Conductive sleeve 62 Magnet roll 63 Bias power supply 64 Cylindrical electrode

Claims (7)

Toner base particles containing a binder resin and a colorant, and an external additive,
The external additive includes zinc oxide fine particles doped with aluminum or gallium and surface-treated.
Toner for electrostatic latent image development.   The electrostatic latent image developing toner according to claim 1, wherein the surface-treated zinc oxide fine particles are zinc oxide fine particles treated with a hydrophobic treatment agent. The zinc oxide fine particles doped with aluminum or gallium and hydrophobized have a specific surface area of 30 to 100 m ² / g,
The volume resistivity of the zinc oxide fine particles doped with aluminum or gallium and hydrophobized is 10 to 1.0 × 10 ⁷ Ω · cm.
The electrostatic latent image developing toner according to claim 2. The binder resin includes a vinyl resin,
The toner base particles have a volume-based average particle size of 5.0 to 8.0 μm,
The toner base particles have an average circularity of 0.945 to 0.980,
The water content of the toner base particles is 0.2 to 1.8% by mass.
The toner for developing an electrostatic latent image according to claim 1.   The electrostatic latent image developing toner according to claim 1, further comprising 1.0% by mass or less of titanium oxide. An electrostatic image developing toner and carrier particles;
The electrostatic latent image developing toner is the electrostatic latent image developing toner according to any one of claims 1 to 5.
Two-component developer for developing electrostatic images.   An electrophotographic image forming method using the electrostatic latent image developing toner according to claim 1 or the electrostatic charge image developing two-component developer according to claim 6. .

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