JP2007058035A - Electrophotographic toner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a toner having a satisfactory charge level even at high temperature and high humidity, being free of overcharging even at low temperature and low humidity, and being superior in the environmental differences in charging. <P>SOLUTION: The electrophotographic toner for electrostatic image development contains toner base particles containing a binder resin and a colorant, wherein one or more kinds of inorganic fine particles have been added to the base particle surface. A type of the inorganic fine particles is aluminum hydroxide particles and the aluminum hydroxide particles have been hydrophobed with a treating agent, capable of reacting with hydroxyl groups in the aluminum hydroxide particles. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electrophotographic toner used in electrophotographic methods, electronic recording methods and the like.

  In electrophotography, an electrostatic latent image formed on the surface of a latent image carrier (photoconductor) is developed with a toner containing a colorant, and the obtained toner image is transferred to the surface of a recording material, which is then heated. An image can be obtained by fixing with a roll or the like. On the other hand, the latent image carrier is cleaned to form an electrostatic latent image again.

  The dry developer used in such electrophotography is a one-component developer using a toner in which a colorant or the like is blended in a binder resin, and a two-component developer in which a carrier is mixed with the toner. Broadly divided. Furthermore, the one-component developer is a magnetic one-component developer that is conveyed by a magnetic carrier using a magnetic force and developed by a magnetic force, and a developer carrier that is charged with a charging roll or the like without using a magnetic powder. It can be classified as a non-magnetic one-component developer that is conveyed and developed.

  In recent years, color machines have also become widespread, and in particular, two-component developers are used for these medium-speed and high-speed machines. In particular, with regard to full color image quality, high image quality close to high-quality printing and silver salt photography is desired.

  Digitization processing is indispensable as a means for achieving high image quality, and the effect of digitization related to such image quality is that complex image processing can be performed at high speed. In particular, for photographic images, gradation correction and color correction are possible, and this is advantageous over analog in terms of gradation characteristics, definition, sharpness, color reproduction, and graininess. Furthermore, it is necessary to faithfully form a latent image created by an optical system as an image output, and as a toner, an activity aimed at faithful reproduction is accelerated as the particle diameter is further reduced.

  For reducing the diameter of the toner, for example, proposals have been made using a small diameter toner having an average particle diameter of 3 to 7 μm (see, for example, Patent Documents 1 to 4).

  However, when the toner particle size is reduced, it becomes difficult to secure the toner charge amount necessary for development, and in some cases, the toner may be charged to a reverse polarity. If a toner with an insufficient charge amount or a toner charged to a reverse polarity is used, image dropout or fogging of non-image areas is likely to occur. On the other hand, if the charge amount is too high, the electrostatic adhesion force becomes too large, resulting in density reduction and non-uniform image structure. Considering the above, charging control of the toner is extremely important when reducing the particle size of the toner.

  As a method for producing this small-diameter toner, in recent years, a toner production method using an emulsion polymerization aggregation method has been proposed as a means that enables control to a desired particle size, shape, and surface structure (for example, Patent Documents). 5 and 7). As these manufacturing methods, a dispersion liquid formed by emulsion polymerization of a polymerizable monomer of a binder resin is mixed with a dispersion liquid containing a coloring material, a release agent, and a charge control material as necessary. An emulsion polymerization aggregation method for obtaining toner particles by aggregation, heat fusion, and a solution of a polymerizable monomer, a colorant, a release agent, and a charge control agent as required. Suspension polymerization method in which a polymer is suspended in an aqueous solvent for polymerization. With these wet-type toners, shape control and particle size control are also possible.

  On the other hand, it is generally known that inorganic fine particles are externally added to colored particles (toner particles) for the purpose of obtaining good developability, cleaning properties, and transferability by adjusting the chargeability and fluidity of the toner.

As these inorganic fine particles, silica, titanium oxide, and alumina have been mainly used.
Other examples include aluminum hydroxide, magnesium oxide, calcium carbonate, barium sulfate, and zinc oxide.

  For example, aluminum oxide, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, chromium oxide, cesium oxide, antimony trioxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, carbonization A total of 17 kinds of inorganic fine particle additive materials of silicon, silica oxide, and silicon nitride have been proposed (see, for example, Patent Document 7). Further, it has been proposed to add aluminum hydroxide fine particles to the toner surface (see, for example, Patent Document 8). However, these inorganic oxide fine particles have a high hygroscopic property, and even when added to a toner, there is a problem that charging under high temperature and high humidity is low.

  On the other hand, studies have been made on improving the level of charge and improving the difference in charge environment by applying a hydrophobic treatment. A proposal has been made to prevent overcharging in a low-temperature, low-humidity environment by using hydrophobized silica fine particles (see, for example, Patent Document 9). It has also been proposed to maintain a stable charge amount under any environment by using hydrophobic titania (see, for example, Patent Documents 10 and 11). Furthermore, a hydrophobized alumina having excellent frictional charging characteristics has been proposed (see, for example, Patent Document 12).

  With regard to the hydrophobizing agent, inorganic fine particles such as silane coupling agents, titanium oxide surface-treated with silicone oil, and silica oxide are used as examples of the inorganic fine particle treating agent for the purpose of improving the chargeability and its environmental stability. Has been proposed (see, for example, Patent Document 13).

  As described above, it is difficult to control charging by reducing the particle size of the toner. In addition, the toner surface area per unit weight is increased by reducing the diameter, so that the hygroscopicity of the toner itself is increased. Furthermore, the toner produced by a wet process suitable for reducing the diameter tends to have higher surface hydrophilicity than the kneaded and pulverized toner. These toners with high hygroscopicity have a problem of low charge under high temperature and high humidity.

  For these reasons, it has been desired to design a toner that raises the charge level of toner under high temperature and high humidity and has a small difference in charging environment. In particular, even when a toner having a small diameter and a wet manufacturing method is used, it is necessary to develop a toner having excellent charging characteristics.

  Therefore, the present inventors examined many proposals described above. First, in addition of inorganic fine particles, aluminum oxide, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, chromium oxide, cesium oxide, antimony trioxide, zirconium oxide, barium sulfate, carbonate In all of barium, calcium carbonate, silicon carbide, silica, silicon nitride, and aluminum hydroxide, the charge level under high temperature and high humidity could not be obtained. Only the high charge level of silica was confirmed, but on the contrary, the charge of silica was too high under low temperature and low humidity, and it was not possible to obtain a charge level usable in both environments.

  Further, among these, hard inorganic fine particles such as aluminum oxide, zirconium oxide and strontium titanate have a problem of damaging the photoreceptor in a cleaning system using a blade.

  In addition, silica, alumina, and titania that had been proposed in the past were subjected to hydrophobic treatment. As a result, there was a tendency that the charge under high temperature and high humidity was improved to some extent by the hydrophobic treatment. However, those obtained by hydrophobizing titanium oxide and aluminum oxide were not sufficiently charged at high temperature and high humidity. In particular, the charge level is insufficient for a small diameter toner made by a wet process.

  With regard to silica, it was possible to increase the charge level under high temperature and high humidity, but no matter how hydrophobic treatment was performed, overcharge in a low temperature and low humidity environment could not be suppressed. As a result, silica having the worst difference in charging environment between high temperature and high humidity and low temperature and low humidity was silica regardless of the treatment.

  Regarding the hydrophobizing agent, the hydrophobizing treatment was examined based on titanium oxide and aluminum oxide. Titanium oxide and aluminum oxide treated with hexamethyldisilazane have a small effect of increasing charging, and the influence of inorganic fine particles is strongly reflected in charging, which is insufficient for improving the charging level under high temperature and high humidity.

  Titanium oxide and aluminum oxide hydrophobized with silanes have an effect of improving the charge level under high temperature and high humidity, but the effect is not sufficient. Since these hexamethylsilazane and silanes are treated by reacting with the surface OH groups of the inorganic fine particles, the amount of treatment is limited, and sufficient effects cannot be obtained. In other words, if the treatment can be increased, it is expected that the charge will be raised under high temperature and high humidity, but sufficient charge imparting ability could not be obtained with inorganic fine particles having limited OH groups as reaction sites. Even if the treatment was performed in excess of the OH group, the hydrophobizing agents were polycondensed with each other and were present on the surface in a form that adhered without being chemically bonded. On the contrary, this resulted in charging disturbance such as spreading of the charge distribution. .

Since titanium oxide and aluminum oxide treated with silicone oil do not have to be reactive with surface OH groups, the treatment amount is not limited and the charge level can be increased by increasing the treatment amount. However, although the charge level increased, the charging characteristics were similar to those of silica, and the difference in charging environment was worsened. In other words, even if a core material such as titanium oxide or aluminum oxide, which has a good charging environment difference, is treated with silicone oil, the charge level under high temperature and high humidity is increased, and charging under low temperature and low humidity is further achieved. As a result, the difference in charging environment was not improved.
JP-A-6-75430 JP-A-6-332237 Japanese Patent Laid-Open No. 7-77825 JP-A-7-146589 Japanese Patent Laid-Open No. 63-282275 JP-A-6-250439 JP-A-4-070762 JP 2000-147825 A Japanese Patent Application No. 3-43788 JP-A 64-62667 JP 2000-3218 A Japanese Patent Laid-Open No. 11-7149 JP-A-11-295921

  The present invention aims to achieve the following problems. That is, the present invention provides a toner that has a sufficient charge level even under high temperature and high humidity, and that is not overcharged even under low temperature and low humidity, and that is excellent in charging environment difference.

  As a result of intensive studies to achieve the above object, the present inventors have studied materials for inorganic fine particles to be externally added to the toner surface and processing methods thereof, and use the following toner configuration (the present invention). Thus, it has been found that the above object can be achieved.

  The present inventors have examined a large number of inorganic fine particles, and found that hydrophobic treatment is important for improving charging characteristics. Specifically, (1) the amount of hydrophobizing treatment is large, and (2) the hydrophobizing agent is chemically bonded to inorganic fine particles as external additives. Then, it was confirmed that when the amount of hydrophobic treatment was large, it was less affected by humidity under high temperature and high humidity, water absorption of inorganic fine particles was protected, and the charging characteristics by the hydrophobic portion worked effectively.

  On the other hand, it was found that the hydrophobizing agent must be chemically bonded to the surface of the inorganic fine particles (particularly, the hydroxyl group on the surface). If it does not react with a hydroxyl group, the hydroxyl group on the surface induces hydrophilicity even if the hydrophobizing treatment is carried out, and the hydrophobicity is not sufficient. Further, the hydrophobic treatment agent physically adsorbed on the surface to which the treatment agent is not bonded peeled off over time, and it was difficult to maintain the hydrophobic treatment over time.

  In order to increase the amount of hydrophobic treatment by reacting with a hydroxyl group, the sample was charged with a hydrophobic treatment agent amount with respect to inorganic fine particles. As a result, there was an optimum value for the treatment agent amount. It was found that the characteristics could not be extracted even if the amount was too large.

  This is presumably because the treating agents cannot bind to the surface OH groups of the inorganic fine particles and are polycondensed with each other, which adversely affects the charging characteristics. For this reason, it was confirmed that each inorganic fine particle has an optimum hydrophobization treatment amount, and that the charge level of the inorganic fine particle having a larger optimum treatment amount is higher at high temperature and high humidity.

  As a result of intensive studies on inorganic fine particles capable of increasing the optimum processing amount, it was found that aluminum hydroxide having many OH groups on the surface is suitable. When a hydrophobizing agent that reacts with OH groups was applied to aluminum hydroxide, a larger amount of the treating agent could be reacted with silica, aluminum oxide, or titanium oxide having the same specific surface area.

  As a result, when the hydrophobized aluminum hydroxide fine particles were added to the toner, it was possible to obtain a toner having a high charge level under high temperature and high humidity and a good charging environment difference. It is possible to obtain an external additive having unprecedented charging characteristics and environmental stability by treating the aluminum hydroxide, which has been used only by itself, with the optimum amount of the hydrophobizing treatment that reacts with the hydroxyl group. did it.

  In contrast to the conventionally used alumina having a Mohs hardness of 9 and titania having a Mohs hardness of 7, aluminum hydroxide has a Mohs hardness of about 4. For this reason, it has been confirmed that scratches or abrasion of the photoreceptor due to these inorganic fine particles, which has been a problem in the past, will not occur.

  The present invention has been conceived from the above findings. That is, the present invention is an electrostatic charge image developing toner comprising toner mother particles containing at least a binder resin and a colorant, wherein at least one kind of inorganic fine particles are added to the surface of the mother particles, One kind of inorganic fine particles is aluminum hydroxide particles, and the aluminum hydroxide particles are hydrophobized with a treating agent that reacts with a hydroxyl group in the aluminum hydroxide particles. It is.

  The present invention preferably includes at least one of the following first to fifth aspects.

(1) A 1st aspect is an aspect in which the said hydrophobization process is a process by alkylsilane.
(2) A second aspect is an aspect in which the toner base particles are produced by a wet manufacturing method.
(3) A 3rd aspect is an aspect whose actual processing amount of the said hydrophobization process is 25 mass parts or more with respect to 100 mass parts of said aluminum hydroxide particles.
(4) A fourth aspect is an aspect in which the aluminum hydroxide is crystalline boehmite.
(5) A 5th aspect is an aspect which contains crystalline resin as a component of the said binder resin.

  According to the present invention, it is possible to provide a toner that has a sufficient charge level even under high temperature and high humidity, and that is not overcharged even under low temperature and low humidity, and is excellent in charging environment difference.

  Hereinafter, the present invention will be described in detail. However, it is not limited by this.

  The present invention relates to a toner for developing an electrostatic charge image comprising toner mother particles containing a binder resin and a colorant, wherein one or more inorganic fine particles are added to the surface of the mother particles. The toner for electrophotography, wherein the seed is aluminum hydroxide particles, and the aluminum hydroxide particles are hydrophobized with a treating agent that reacts with a hydroxyl group in the aluminum hydroxide particles. Details will be described below.

<Toner base particles>
The toner base particles in the electrophotographic toner of the present invention (sometimes simply referred to as “toner”) contain a binder resin and a colorant, and optionally contain other components.

(Binder resin)
As the binder resin for the toner used in the present invention, known resins can be used. In particular, a binder resin having crystallinity is effective as a resin excellent in low-temperature fixing.

  Binder resins include styrenes such as styrene and chlorostyrene; monoolefins such as ethylene, propylene, butylene and isoprene; vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzoate and vinyl butyrate; methyl acrylate , Α-methylene aliphatic monocarboxylic acid esters such as ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, dodecyl methacrylate; vinyl Homopolymers and copolymers of vinyl ethers such as methyl ether, vinyl ethyl ether, vinyl butyl ether; vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, vinyl isopropenyl ketone; Typical binder resins include polystyrene, styrene-alkyl acrylate copolymer, styrene-alkyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer. Examples thereof include coalescence, polyethylene, and polypropylene. Further examples include polyester, polyurethane, epoxy resin, silicone resin, polyamide, modified rosin, paraffin wax and the like. Among these, styrene-alkyl acrylate copolymers and styrene-alkyl methacrylate copolymers are particularly preferable.

  Specific examples of the crystalline resin include long-chain alkyl dicarboxylic acids such as adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, tridecanedioic acid, butanediol, pentanediol, Polyester resins using long-chain alkyl or alkenyl diols such as hexanediol, heptanediol, octanediol, nonanediol, decanediol, and batyl alcohol; amyl (meth) acrylate, hexyl (meth) acrylate, (meth) Heptyl acrylate, octyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, undecyl (meth) acrylate, tridecyl (meth) acrylate, myristyl (meth) acrylate, (meth) acrylic Cetyl acid, (meth) acrylic acid Vinyl resins using long-chain alkyls such as allyl, oleyl (meth) acrylate, and behenyl (meth) acrylate, and (meth) acrylic esters of alkenyl; and the like. From the viewpoint of chargeability and adjustment of the melting point within a preferable range, a polyester resin-based crystalline resin is preferable.

(Coloring agent)
The colorant of the toner is not particularly limited and may be either a dye or a pigment, but a pigment is preferable from the viewpoint of light resistance and water resistance.

  Preferred pigments include carbon black, aniline black, aniline blue, calcoil blue, chrome yellow, ultramarine blue, DuPont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green oxalate, lamp black, rose bengal, Quinacridone, benzidine yellow, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 185, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 180, C.I. I. Pigment yellow 97, C.I. I. Pigment yellow 74, C.I. I. Pigment blue 15: 1, C.I. I. A known pigment such as CI Pigment Blue 15: 3 can be used.

Magnetic powder can also be used as a colorant. As the magnetic powder, known magnetic materials such as ferromagnetic metals such as cobalt, iron and nickel, alloys and oxides of metals such as cobalt, iron, nickel, aluminum, lead, magnesium, zinc and manganese can be used.
The above colorants can be used alone or in combination of two or more. The content of the colorant in the toner of the present invention is preferably 0.1 to 40 parts by weight, and more preferably 1 to 30 parts by weight with respect to 100 parts by weight of the total toner raw material. In addition, by appropriately selecting the type of the colorant, each color toner such as yellow toner, magenta toner, cyan toner, and black toner can be obtained.

(Other ingredients)
A release agent or a charge control agent may be added to the toner base particles as necessary. Generally as a mold release agent, it uses for the purpose of improving mold release property. Specific examples of the release agent include low molecular weight polyolefins such as polyethylene, polypropylene, and polybutene; silicones having a softening point by heating; fatty acid amides such as oleic acid amide, erucic acid amide, ricinoleic acid amide, and stearic acid amide Plant waxes such as carnauba wax, rice wax, candelilla wax, wood wax, jojoba oil; animal waxes such as beeswax; montan wax, ozokerite, ceresin, paraffin wax, microcrystalline wax, Fischer-Tropsch wax, etc. Mineral / petroleum waxes; ester waxes such as fatty acid esters, montanic acid esters, and carboxylic acid esters. In this invention, these mold release agents may be used individually by 1 type, and may use 2 or more types together.

  The content of the release agent is preferably 1 to 20 parts by weight, and more preferably 2 to 15 parts by weight with respect to 100 parts by weight of the total raw material of the toner base particles. If the amount is less than 1 part by weight, the effect of adding the release agent may not be obtained. If the amount exceeds 20 parts by weight, the adverse effect on the chargeability tends to appear, and the toner is easily destroyed inside the developing machine, so that the release is performed. In addition to the effect that the agent or toner resin becomes spent on the carrier and the charge is likely to decrease, for example, when color toner is used, the surface of the image at the time of fixing becomes insufficient. This is not preferable because the release agent may easily stay in the image and the transparency may deteriorate.

  The melting point of the release agent is preferably 50 to 120 ° C, more preferably 60 to 100 ° C. When the melting point of the release agent is less than 60 ° C., the change temperature of the release agent may be too low, and the blocking resistance may be inferior, or the developability may deteriorate when the temperature in the copying machine increases. When the melting point exceeds 120 ° C., although there is an effect on hot offset, the toner may not be heated to the melting point of the release agent practically and may not substantially exhibit the action of the release agent. .

  The charge control agent is generally used for the purpose of improving the chargeability. Examples of the charge control agent include metal-containing azo compounds such as chromium azo dyes, iron azo dyes, and aluminum azo dyes; salicylic acid metal complexes, nigrosine and quaternary ammonium salts.

  The volume average particle size of the toner of the present invention is preferably 2 to 8 μm, and more preferably 3 to 6 μm. Moreover, as a number average particle diameter, 2-8 micrometers is preferable. Further, the value of (volume average particle diameter ÷ number average particle diameter), which is an index of particle size distribution, is preferably 1.6 or less, and more preferably 1.5 or less. When this value is larger than 1.6, the spread of the particle size distribution becomes large, so that the distribution of the charge amount becomes wide and reverse polarity toner or low charge toner is likely to be generated.

  The toner base particles were produced by, for example, a kneading pulverization method in which a binder resin, a colorant, and a release agent, a charge control agent, and the like as necessary are kneaded, pulverized, and classified; A method of changing the shape of particles by mechanical impact force or thermal energy; emulsion polymerization of a polymerizable monomer of a binder resin, a formed dispersion, a colorant, and, if necessary, a release agent, Emulsion polymerization aggregation method to obtain toner particles by mixing with a dispersion such as a charge control agent, and agglomerating and heat fusing; a polymerizable monomer to obtain a binder resin, a colorant, and if necessary Suspension polymerization method in which a solution of a release agent, a charge control agent, etc. is suspended in an aqueous solvent for polymerization; a binder resin, a colorant, and a solution of a release agent, a charge control agent, etc. as necessary For example, a solution suspension method of suspending in an aqueous solvent and granulating can be used. In addition, a manufacturing method may be performed in which the toner obtained by the above method is used as a core, and agglomerated particles are further adhered and heat-fused to have a core-shell structure. From the viewpoint of the shape controllability of the toner base particles, it is preferably a wet production method of any one of an emulsion polymerization aggregation method, a suspension polymerization method and a dissolution suspension method.

  The toner base particles produced as described above preferably have a small particle size for the purpose of improving the image quality. However, if the diameter is too small, development is difficult with the conventional system from the viewpoint of charging and fluidity. That is, the volume average particle size is preferably in the range of 2 to 8 μm, and more preferably in the range of 4 to 7 μm.

  If it exceeds 8 μm, the image quality such as reproducibility of fine lines and halftone graininess deteriorates, and it is difficult to obtain good image quality when outputting photographic image quality. On the other hand, if it is less than 2 μm, the powder characteristics and the charging characteristics are extremely deteriorated, and it may be difficult to output at high speed by a conventional machine.

  A known method may be used for the particle size measurement method in the present invention. An example of the measurement method is shown below. A Coulter counter TA-II type (manufactured by Beckman-Coulter) is used as the measuring apparatus, and ISOTON-II (manufactured by Beckman-Coulter) is used as the electrolyte. As a measuring method, 0.5 to 50 mg of a measurement sample is added to 2 ml of a 5% aqueous solution of a surfactant, preferably sodium alkylbenzenesulfonate as a dispersant. This is added to 100 to 150 ml of the electrolytic solution. The electrolytic solution in which the sample is suspended is subjected to a dispersion treatment with an ultrasonic disperser for about 1 minute, and the particle size distribution of particles of 2 to 60 μm is measured using the Coulter counter TA-II with an aperture diameter of 100 μm. Obtain volume average distribution and number average distribution. The number of particles to be measured is preferably 50,000. The volume average particle size is obtained from the volume average distribution and the number average distribution thus obtained.

  The above-mentioned binder resin has a melting point of preferably 50 to 180 ° C, more preferably 60 to 150 ° C. When the melting point is lower than 50 ° C., toner storage stability and image storage stability after fixing may become a problem. On the other hand, when the temperature is higher than 180 ° C., the power consumption of the machine is increased, which may not be economical.

  In the case of a crystalline resin, a plurality of melting peaks may be shown. In the present invention, the maximum peak is regarded as the melting point. For measurement of the glass transition temperature (Tg) of the toner, DSC-7 (differential thermal analyzer) manufactured by Perkin Elmer can be used. The temperature correction of the detection part of the apparatus uses the melting points of indium and zinc, and the correction of heat quantity uses the heat of fusion of indium. For the sample, an aluminum pan is used, and an empty pan is set as a control, and measurement is performed at a heating rate of 10 ° C./min. For calculation of the peak area of the molecular weight, the peak area is sliced for each retention time range, and the distribution ratio is obtained from the area ratio.

<External additive>
(Aluminum hydroxide particles)
Known aluminum hydroxide particles added to the toner base particles can be used. Stoichiometrically, it corresponds to AlO.OH and Al (OH) ₃ . For example, boehmite, diaspore, gibbsite and the like can be mentioned. These aluminum hydroxides can be used alone, but can also be used as composite inorganic fine particles such as those obtained by coating other inorganic fine particles with aluminum hydroxide, mixed crystals with aluminum hydroxide, and the like. The aluminum hydroxide particles are preferably crystalline boehmite from the viewpoint of obtaining particles with little change in charge amount with respect to the environment by appropriately retaining moisture.

(Hydrophobicizing agent)
Although there is no restriction | limiting in particular as a hydrophobization processing agent, For example, a silane coupling agent, a titanate coupling agent, an aluminum coupling agent, etc. are mentioned. These may be used individually by 1 type and may use 2 or more types together. Of these, silane coupling agents are preferred.

  As the silane coupling agent, for example, any one of chlorosilane, alkoxysilane, silazane, and a special silylating agent can be used. Here, the following can be illustrated as a processing agent used for surface treatment.

  That is, methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, phenyltrichlorosilane, diphenyldichlorosilane, tetramethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, tetraethoxysilane, methyltriethoxy Silane, dimethyldiethoxysilane, phenyltriethoxysilane, diphenyldiethoxysilane, isobutyltrimethoxysilane, decyltrimethoxysilane, hexamethyldisilazane, N, O- (bistrimethylsilyl) acetamide, N, N-bis (trimethylsilyl) Urea, tert-butyldimethylchlorosilane, vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxy Run, γ-methacryloxypropyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-mercapto Representative examples include propyltrimethoxysilane and γ-chloropropyltrimethoxysilane.

The amount of the hydrophobizing agent to the aluminum hydroxide particles is preferably 30 parts by mass or more with respect to 100 parts by mass of the aluminum hydroxide particles. More preferably, 35-60 mass parts is good. The amount of the treatment agent varies depending on the particle size, specific surface area, and treatment agent type of the external additive to be treated. When the surface treatment of isobutyltrimethoxysilane is taken as an example for a material having a BET specific surface area of 40 m ² / g, the amount of the treatment agent is preferably 30 parts by mass to 60 parts by mass.

  Moreover, it is preferable that the actual amount of hydrophobizing agents for aluminum hydroxide particles is 25 parts by mass or more, more preferably 25 to 55 parts by mass with respect to 100 parts by mass of aluminum hydroxide particles. By being 25 parts by mass or more, it is possible to more efficiently prevent toner charging failure due to moisture.

(Hydrophobic treatment method)
The hydrophobic treatment method can be processed by a general treatment method. The hydrophobic treatment is performed by immersing particles in a dry method such as a spray drying method in which a treatment agent or a solution containing a treatment agent is sprayed on particles suspended in a gas phase or in a solution containing the treatment agent, and drying. It can be processed by a wet method. The method of immersing inorganic particles in a solution containing this coupling agent and drying is preferable because a uniform coating can be formed.

(Particle size of aluminum hydroxide particles)
In order to exhibit charging characteristics, the particle size of the hydrophobized aluminum hydroxide is preferably 5 nm or more and 200 nm or less. If it is less than 5 nm, it will be buried over time, and the sustainability of the charging effect will be reduced. On the other hand, when the thickness exceeds 200 nm, it is difficult to uniformly disperse and adhere to the toner surface, and fixation to the surface and fluidity deterioration tend to occur. Further, considering the powder characteristics, particularly the reduction of adhesion and the improvement of fluidity, the range of 10 nm to 150 nm is preferable.

(Aluminum hydroxide fine particle addition amount)
The content of the hydrophobized aluminum hydroxide is preferably 0.1% by mass or more and preferably 5% by mass or less in the toner. If it is less than 0.1% by mass, the addition amount is small and the toner base surface is exposed to a large amount, and the charging characteristics may not be improved. On the other hand, if it exceeds 5% by mass, the surface coverage becomes high, and there may be concerns about contamination of the member such as adhesion to the carrier by free external additives and filming on the photoreceptor.

(Other additives)
In addition to the hydrophobized aluminum hydroxide, the toner particles include inorganic fine particles, charge control agents, lubricants, abrasives, and cleaning aids for the purpose of improving charging characteristics, powder characteristics, transfer characteristics, and cleaning characteristics. A known additive such as may be externally added. Known inorganic fine particles can be used. Examples thereof include silica, alumina, titania, metatitanic acid, zinc oxide, zirconia, magnesia, calcium carbonate, magnesium carbonate, calcium phosphate, cerium oxide, and strontium titanate. Examples of the resin fine particles include spherical particles such as PMMA, nylon, melamine, benzoguanamine, and fluorine, and amorphous powders such as vinylidene chloride and fatty acid metal orchards. In addition, the surface treatment of the small-diameter inorganic fine particles is effective because the dispersibility becomes high and the effect of increasing the powder fluidity increases.

(External addition process)
The toner of the present invention is produced by adding the external additive to the toner particles and mixing them. Mixing can be performed by, for example, a V blender, a Henshur mixer, a Ladyge mixer, or the like. Furthermore, if necessary, coarse toner particles may be removed using a vibration classifier, a wind classifier, or the like.

<Electrophotographic developer and carrier>
The electrophotographic toner of the present invention can be made into a two-component developer by mixing with a carrier. As the carrier, it is preferable in terms of charge controllability and resistance controllability to use a resin-coated carrier having a resin coating layer in which a conductive material is dispersed and contained in a matrix resin on a core material. As a volume average particle diameter of a carrier core material, generally 10-100 micrometers is preferable and 20-80 micrometers is more preferable. If it is smaller than 10 μm, the magnetic force per carrier grain is lowered and carrier jumping is likely to occur. When the thickness is larger than 100 μm, there are problems that the toner cannot be sufficiently charged and the image is deteriorated.

  The core material of the carrier is not particularly limited, and examples thereof include magnetic metals such as iron, steel, nickel and cobalt, magnetic oxides such as ferrite and magnetite, glass beads, and the like, from the viewpoint of using the magnetic brush method. Is preferably a magnetic carrier.

  The coating resin includes polyethylene, polypropylene, polystyrene, polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl carbazole, polyvinyl ether, polyvinyl ketone, vinyl chloride-vinyl acetate copolymer, styrene-acrylic acid copolymer. Examples include polymers, straight silicone resins composed of organosiloxane bonds or modified products thereof, fluororesins, polyesters, polyurethanes, polycarbonates, phenol resins, amino resins, melamine resins, benzoguanamine resins, urea resins, amide resins, epoxy resins, etc. However, it is not limited to these.

  The average film thickness of the resin coating layer formed by the above method is usually 0.1 to 10 μm, preferably 0.2 to 5 μm. When the thickness is less than 0.1 μm, the core is easily peeled off, and the core is easily exposed over time, and the charge imparting ability and resistance may be lowered, and stable image quality may not be obtained. When the film thickness exceeds 10 μm, the change with time does not easily occur, but the resistance becomes too high, so that the image quality may be deteriorated. In addition, fluidity may be deteriorated.

  In order to reduce the resistance while increasing the film thickness, the resin matrix may contain conductive powder. Examples of the conductive material include metals such as gold, silver and copper, and titanium oxide, zinc oxide, barium sulfate, aluminum borate, potassium titanate, tin oxide, carbon black, magnetite, and the like. Is not to be done.

  The content of the conductive material is preferably 1 to 50 parts by mass and more preferably 3 to 20 parts by mass with respect to 100 parts by mass of the matrix resin.

  If the carrier resistance is too low, the carrier adheres to the image area of the photoreceptor due to charge injection from the sleeve, or the latent image charge escapes through the carrier, resulting in a latent image distortion or image loss. Such problems arise. On the other hand, when the carrier resistance is high, the carrier charge is less likely to leak, resulting in an edged image. On the other hand, the edge effect is that the image density at the center is very thin on a large image area. Problems arise.

  Examples of the method for producing the carrier include an immersion method in which the powder of the carrier core material is immersed in a solution for forming the coating layer, a spray method in which the solution for forming the coating layer is sprayed on the surface of the carrier core material, and the carrier core material is fluidized air. The fluidized bed method in which the coating layer forming solution is sprayed in a suspended state, the kneader coater method in which the carrier core material and the coating layer forming solution are mixed in the kneader coater to remove the solvent, and the coating resin is made into fine particles. Examples of the powder coating method include a carrier core material and a kneader coater which are mixed at a melting point or higher and cooled to form a film, and the kneader coater method and the powder coat method are particularly preferably used.

  The mixing ratio (mass ratio) of the electrophotographic toner of the present invention and the carrier in the two-component developer is preferably in the range of toner: carrier = 1: 100 to 30: 100, and 3: 100 to A range of about 20: 100 is more preferable.

<Image forming method>
The image forming method of the present invention will be described below.
As the image forming step, a latent image forming step for forming an electrostatic latent image on the surface of the latent image carrier and a developer carried on the developer carrier are used to form an electrostatic image formed on the surface of the latent image carrier. A developing step of developing the latent image to form a toner image, a transfer step of transferring the toner image formed on the surface of the latent image carrier, a cleaning step of cleaning the toner remaining on the surface of the latent image carrier, It includes a fixing step of thermally fixing the transferred image. The developer containing the electrophotographic toner of the present invention is used as the developer.

  The latent image forming step is a step of forming an electrostatic latent image by uniformly charging the surface of the latent image carrier with a charging means and then exposing the latent image carrier with a laser optical system or an LED array. is there. As charging means, a contact-type charger such as corotron or scorotron, and a contact-type charger that charges the surface of the latent image carrier by applying a voltage to a conductive member in contact with the surface of the latent image carrier. Examples of the charger include any charger. However, a contact charging type charger is preferable from the viewpoint that the amount of ozone generated is small, environmentally friendly, and excellent printing durability. In the contact charging type charger, the shape of the conductive member may be any of a brush shape, a blade shape, a pin electrode shape, a roller shape, and the like, but a roller-like member is preferable. The image forming method is not subject to any particular limitation in the latent image forming process.

  The developing step refers to bringing a developer carrier having a developer layer containing at least toner on the surface thereof into contact with or in proximity to the electrostatic latent image on the surface of the latent image carrier. Is a step of forming a toner image on the surface of the latent image carrier. The development method can be performed using a known method, but examples of the development method using a two-component developer include a cascade method and a magnetic brush method. The image forming method is not particularly limited with respect to the development method.

  The cleaning step is a step of removing untransferred toner, paper dust, dust, etc. adhering to the surface of the latent image carrier by bringing a blade, brush, roll, etc. into direct contact with the surface of the latent image carrier. The most commonly employed method is a blade cleaning method in which a rubber blade such as polyurethane is pressed against the latent image carrier. When a toner having a small shape factor and a small particle diameter that is difficult to clean is used, it is effective to increase the resilience of the blade material. In addition, it is possible to select cleaning conditions suitable for each toner by adjusting the hardness of the blade material, the pressing accuracy, the nip amount with respect to the photoreceptor, and the like.

  The fixing step is a step of fixing the toner image transferred to the surface of the recording medium with a fixing device. As the fixing device, a heat fixing device using a heat roll is preferably used. The heat fixing device includes a heater roller for heating inside a cylindrical metal core, a fixing roller in which a so-called release layer is formed by a heat resistant resin coating layer or a heat resistant rubber coating layer on the outer peripheral surface thereof, and the fixing roller. The pressure roller or the pressure belt is disposed in pressure contact with the roller and has a heat-resistant elastic layer formed on the outer peripheral surface of the cylindrical metal core or the surface of the belt-like base material. The fixing process of the unfixed toner image is performed by inserting a recording medium on which an unfixed toner image is formed between a fixing roller and a pressure roller or a pressure belt, so that a binder resin, an additive, etc. Fix by heat melting. In the image forming method, the fixing method is not particularly limited.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. In the following description, “part” means “part by mass” unless otherwise specified.

The particle size distribution measurement in this example will be described. A Coulter counter TA-II type (manufactured by Beckman Coulter, Inc.) was used as the measuring apparatus, and ISOTON-II (manufactured by Beckman Coulter, Inc.) was used as the electrolyte. As a measurement method, 1.0 mg of a measurement sample is added to 2 ml of a 5% aqueous solution of a surfactant, preferably sodium alkylbenzenesulfonate, as a dispersant. This was added to 100 ml of the electrolytic solution to prepare an electrolytic solution in which the sample was suspended.

  The electrolytic solution in which the sample is suspended is subjected to a dispersion treatment with an ultrasonic disperser for 1 minute, and the particle size distribution of particles having a diameter of 2 to 60 μm is measured using the Coulter counter TA-II with an aperture diameter of 100 μm. Average distribution and number average distribution are obtained. The number of particles to be measured was 50,000.

  Moreover, when the particle | grains to measure were less than 2 micrometers, it measured using the laser diffraction type particle size distribution measuring apparatus (LA-700: made by Horiba, Ltd.). As a measurement method, a sample in a dispersion is adjusted to have a solid content of about 2 g, and ion exchange water is added thereto to make about 40 ml. This is put into the cell until an appropriate concentration is reached, waits for about 2 minutes, and is measured when the concentration in the cell becomes almost stable. The obtained volume average particle diameter for each channel was accumulated from the smaller volume average particle diameter, and the volume average particle diameter was determined to be 50%.

  When measuring powders such as external additives, 2 g of a measurement sample is added to 50 ml of a 5% aqueous solution of a surfactant, preferably sodium alkylbenzenesulfonate, and dispersed for 2 minutes with an ultrasonic disperser (1000 Hz). Then, a sample was prepared and measured by the same method as the above-mentioned dispersion.

-Preparation of toner (I)-
[Manufacture of toner base particles]
(Preparation of resin fine particle dispersion)
370 parts of styrene, 30 parts of n-butyl acrylate, 8 parts of acrylic acid, 24 parts of dodecanethiol and 4 parts of carbon tetrabromide were mixed and dissolved in a nonionic surfactant (Nonipol 400: Sanyo Chemical Co., Ltd. )) 6 parts and 10 parts of anionic surfactant (Neogen SC: manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) were dissolved in 550 g of ion-exchanged water, and the mixture was slowly mixed for 10 minutes. 50 g of ion exchange water in which 4 g of ammonium persulfate was dissolved was added. After carrying out nitrogen substitution, the inside of the flask was stirred and heated in an oil bath until the contents reached 70 ° C., and emulsion polymerization was continued for 5 hours. As a result, a resin fine particle dispersion in which resin particles having a volume average particle size of 150 nm, Tg = 52 ° C., and weight average molecular weight Mw = 10500 was obtained. The solid content concentration of this dispersion was 40% by mass.

(Preparation of colorant dispersion (1))
Carbon black (Mogal L: Cabot) ... 60 parts Nonionic surfactant (Nonipol 400: Sanyo Chemical Co., Ltd.) ... 5 parts Ion-exchanged water ... 240 parts

  The above components are mixed, dissolved, stirred for 10 minutes using a homogenizer (Ultra Turrax T50: manufactured by IKA), then dispersed with an optimizer (colorant (carbon) having an average particle size of 250 nm. Black) A colorant dispersant (1) in which particles were dispersed was prepared.

(Preparation of colorant dispersion (2))
Cyan pigment (CI Pigment Blue 15: 3, manufactured by Dainichi Seika Co., Ltd.) ... 60 parts nonionic surfactant (Nonipol 400: manufactured by Sanyo Chemical Co., Ltd.) ... 5 parts ion-exchanged water ... 240 parts

  The above components are mixed, dissolved, stirred for 10 minutes using a homogenizer (Ultra Turrax T50: manufactured by IKA), and then dispersed with an optimizer to give a colorant having a volume average particle diameter of 250 nm ( Cyan pigment) A colorant dispersant (2) in which particles were dispersed was prepared.

<Preparation of Colorant Dispersion (3)>
Magenta pigment (CI Pigment Red122, manufactured by Dainichi Seika Co., Ltd.) ... 60 parts Nonionic surfactant (Nonipol 400: manufactured by Sanyo Chemical Co., Ltd.) ... 5 parts Ion-exchanged water ... 240 parts

  The above components are mixed, dissolved, stirred for 10 minutes using a homogenizer (Ultra Turrax T50: manufactured by IKA), and then dispersed with an optimizer to give a colorant having a volume average particle diameter of 250 nm ( Magenta pigment) A colorant dispersant (3) in which particles were dispersed was prepared.

<Preparation of colored dispersion (4)>
Yellow pigment (CI Pigment Yellow 180, manufactured by Dainichi Seika Co., Ltd.) ... 90 parts Nonionic surfactant (Nonipol 400: manufactured by Sanyo Chemical Co., Ltd.) ... 5 parts Ion-exchanged water ... 240 parts

  The above components are mixed, dissolved, stirred for 10 minutes using a homogenizer (Ultra Turrax T50: manufactured by IKA), and then dispersed with an optimizer to give a colorant having a volume average particle diameter of 250 nm ( A colorant dispersant (4) in which yellow pigment) particles were dispersed was prepared.

<Releasing agent dispersion>
100 parts of paraffin wax (HNP0190: Nippon Seiwa Co., Ltd., melting point 85 ° C.)
Cationic surfactant: 5 parts (Sanisol B50: manufactured by Kao Corporation)
Ion exchange water: 240 parts

  The above components were dispersed in a round stainless steel flask using a homogenizer (Ultra Turrax T50: manufactured by IKA) for 10 minutes, and then dispersed with a pressure discharge type homogenizer, and the average particle size was 550 nm. A release agent dispersion liquid in which the mold agent particles were dispersed was prepared.

<Preparation of toner mother particles K1>
Resin fine particle dispersion: 234 parts Colorant dispersion (1): 30 parts Release agent dispersion: 50 parts Polyaluminum hydroxide (Pho2S manufactured by Asada Chemical Co., Ltd.): 0.5 parts Ion exchange water ... 600 parts

  The above components were mixed and dispersed in a round stainless steel flask using a homogenizer (Ultra Turrax T50: manufactured by IKA), and then heated to 40 ° C. while stirring the flask in a heating oil bath. . After maintaining at 40 ° C. for 30 minutes, it was confirmed that aggregated particles having a D50 of 4.5 μm were produced. Further, the temperature of the heating oil bath was raised and maintained at 56 ° C. for 1 hour, and D50 was 5.3 μm. Thereafter, 26 parts by weight of the resin fine particle dispersion was added to the dispersion containing the aggregate particles, and then the temperature of the heating oil bath was raised to 50 ° C. and held for 30 minutes. The dispersion containing the aggregated particles was added with 1N sodium hydroxide to adjust the pH of the system to 7.0, and then the stainless steel flask was sealed and heated to 80 ° C. while continuing stirring using a magnetic seal. And held for 4 hours. After cooling, the toner base particles were separated by filtration, washed four times with ion exchange water, and then lyophilized to obtain toner base particles K1. The toner base particle K1 had a D50 of 5.9 μm and an average shape factor SF1 of 132.

  The average shape factor (SF1) was determined by the following formula.

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

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

<Preparation of toner base particles C1>
Toner mother particles C1 were obtained in the same manner as K1 except that the colored particle dispersion (2) was used instead of the colored particle dispersion (1). D50 of the toner base particle C1 was 5.8 μm, and the average shape factor SF1 was 131.

<Preparation of toner mother particles M1>
Toner mother particles M1 were obtained in the same manner as K1 except that the colored particle dispersion (3) was used instead of the colored particle dispersion (1). The toner base particles M1 had a D50 of 5.5 μm and an average shape factor SF1 of 135.
<Preparation of toner mother particles Y1>
Toner mother particles Y1 were obtained in the same manner as K1 except that the colored particle dispersion (4) was used instead of the colored particle dispersion (1). D50 of the toner base particles Y1 was 5.9 μm, and the average shape factor SF1 was 130.

-Preparation of toner (II)-
--Synthesis of crystalline polyester resin (1)-
In a heat-dried three-necked flask, 17.4 parts by weight of 1,10-decanediol, 2.2 parts by weight of sodium dimethyl 5-sulfoisophthalate, 10 parts by weight of dimethyl sulfoxide, and 0.03 of dibutyltin oxide as a catalyst were used. Then, the air in the container was replaced with nitrogen gas by a depressurization operation to create an inert atmosphere, and the mixture was stirred at 180 ° C. for 3 hours by mechanical stirring. Dimethyl sulfoxide was distilled off under reduced pressure, 26.5 parts by weight of dimethyl dodecanedioic acid was added under a nitrogen stream, and the mixture was stirred at 180 ° C. for 1 hour.

Thereafter, the temperature was gradually raised to 220 ° C. under reduced pressure, and the mixture was stirred for 30 minutes. When it became viscous, it was air-cooled, the reaction was stopped, and 36 parts by weight of crystalline polyester resin (1) was synthesized. . The crystalline polyester resin (1) obtained had a weight average molecular weight (M _W ) of 9,200 and a number average molecular weight (M _n ) of 6,000 as determined by gel permeation chromatography.

  Further, when the melting point (Tm) of the crystalline polyester resin (1) was measured by a differential scanning calorimeter (DSC) by the above-described measuring method, it had a clear peak and the peak top temperature was 79 ° C. Met. The content ratio of the copolymerization component (5-sulfoisophthalic acid component) and the dodecanedioic acid component measured and calculated from the NMR spectrum of the resin was 7.5: 92.5.

-Production of toner base particles C2-
<Preparation of resin particle dispersion (1)>
150 parts by weight of the obtained crystalline polyester resin (1) was placed in 850 parts by weight of distilled water, and mixed and stirred with a homogenizer (IKA Japan: Ultra Tarax) while heating to 85 ° C. to disperse the resin particles. A liquid (1) was obtained.

<Preparation of Colorant Dispersion (5)>
250 parts by weight of a phthalocyanine pigment (manufactured by Dainichi Seika Co., Ltd .: PV FAST BLUE), 20 parts by weight of an anionic surfactant (manufactured by Daiichi Kogyo Seiyaku Co., Ltd .: Neogen RK), 730 parts by weight of ion-exchanged water, Were mixed and dissolved, and then dispersed using a homogenizer (manufactured by IKA: Ultra Tarax) to prepare a colorant dispersion (5) in which a colorant (phthalocyanine pigment) was dispersed.

<Preparation of aggregated particles>
2400 parts by weight of resin particle dispersion (1), 100 parts by weight of colorant dispersion (5), 63 parts by weight of release agent dispersion, 10 parts by weight of lauroyl peroxide, and aluminum sulfate (manufactured by Wako Pure Chemical Industries, Ltd.) ) After 5 parts by weight and 100 parts by weight of ion-exchanged water are contained in a round stainless steel flask, adjusted to pH 2.0, and dispersed using a homogenizer (manufactured by IKA: Ultra Turrax T50) The mixture was heated in an oil bath for heating to 72 ° C. with stirring. After maintaining at 72 ° C. for 3 hours, observation with an optical microscope confirmed that aggregated particles having a volume average particle diameter of about 5.0 μm were formed. After further heating and stirring at 72 ° C. for 1 hour, observation with an optical microscope confirmed that aggregated particles having a volume average particle diameter of about 5.5 μm were formed.

<Fusion process>
The pH of the aggregated particles was 2.4. Therefore, an aqueous solution obtained by diluting sodium carbonate (manufactured by Wako Pure Chemical Industries, Ltd.) to 0.5% by weight was gently added to adjust the pH to 5.0. did.

  Thereafter, the reaction product was filtered, sufficiently washed with ion-exchanged water, and then dried using a vacuum drier to obtain toner base particles C2. The obtained toner base particles C2 were measured for volume average particle size using a Coulter counter [TA-II] type (aperture diameter: 50 μm, manufactured by Coulter), and the D50 of the toner base particles C2 was 5.5 μm. The average shape factor SF1 was 131.

-Fabrication of carrier-
14 parts of toluene, 2 parts of styrene-methyl methacrylate copolymer (component ratio: 80/20, weight average molecular weight 70000), and 0.2 part of carbon black (R330: manufactured by Cabot) are mixed and stirred with a stirrer for 10 minutes. Thus, a coating layer forming solution in which carbon black was dispersed was prepared. Next, this coating solution and 100 parts of ferrite particles (volume average particle size: 38 μm) are put in a vacuum degassing kneader and stirred at 60 ° C. for 30 minutes, and then degassed by further reducing pressure while heating. The carrier was prepared by drying. This carrier had a volume resistivity of 10 ¹¹ Ωcm when an electric field of 800 V / cm was applied.

The hydrophobic treatment of the inorganic fine particles was performed as follows.
-Hydrophobic treatment of inorganic fine particles (silane-based treatment)-
Into a reaction vessel, 80 parts by mass of inorganic fine particles are added to a mixed solvent in which 1000 parts by mass of pure water and 100 parts by mass of 2-propanol are mixed to form a slurry. Next, with respect to the amount of the inorganic fine particles, the treatment agent types shown in Table 1 below were charged into the reaction vessel in the form of the same treatment agent amount shown in Table 1 as a slurry. After replacing the inside of the reaction vessel with dry nitrogen gas, 30 parts by weight of 0.1N HCl was dropped after the temperature was raised, and the temperature of the mixed solution was raised to about 80 ° C. with stirring under a nitrogen gas stream.

  Thereafter, the reaction was stirred for 3 hours while heating and refluxing in an oil bath. After cooling, the mixed solution was taken out, fine particles were separated by a centrifuge, and the supernatant was removed. The operation of mixing and stirring the filtered fine particles in a 10% methanol aqueous solution and centrifuging is repeated three times. Furthermore, after mixing and stirring in pure water and repeating the centrifugation operation three times, the fine particle wet product was lyophilized to remove moisture. After vacuum drying at 160 ° C. for 2 hours, the mixture was crushed in an agate mortar and sieved with a 40 μm sieving mesh, and used as inorganic fine particles for toner addition.

-Hydrophobic treatment of inorganic fine particles (dimethylsilicone oil-based treatment)-
80 parts by mass of inorganic fine particles are added to a mixed solvent in which 1000 parts by mass of pure water and 100 parts by mass of 2-propanol are mixed in a reaction vessel to form a slurry. Next, with respect to the amount of the inorganic fine particles, the treatment agent types shown in Table 1 below are charged into the reaction vessel in the form of a slurry similarly in the amount of the treatment agent shown in Table 1. The inside of the reaction vessel is replaced with dry nitrogen gas, and then stirred for 30 minutes while heating and refluxing in an oil bath. Thereafter, the reaction vessel is connected to the evaporator, and the solvent is removed. After drying, vacuum drying was performed at 160 ° C. for 2 hours, and then crushed with an agate mortar and sieved with a 40 μm sieving mesh, was used as inorganic fine particles for toner addition.

  The actual treatment amount of the hydrophobized product according to Table 1 above is set from the room temperature to 1000 ° C. at a heating rate of 30 ° C./min by setting inorganic fine particles to be measured in a thermogravimetric measuring device (TGA-50H) manufactured by Shimadzu Corporation. The mass was decreased by heating to ℃. When the thermal weight reduction amount of the untreated product is A and the thermal weight reduction amount of the treated product is B, B-A is the substantial processing amount. The results are shown in Table 2.

  The toners according to Examples 1 to 4 and Comparative Examples 1 to 10 shown in Tables 1 and 2 will be described below.

(Toner of Example 1: As hydrophobized inorganic fine particles, an external additive having been treated with 30 parts by mass of decylsilane with respect to 100 parts by mass of aluminum hydroxide particles)
As shown in Table 1, 100 parts of the toner base particles Y1, M1, C1, and K1 were each hydrophobized with 30 parts by mass of decylsilane (substantially hydrophobizing amount: 100 parts by mass). 28.5 wt%) and 1.5 parts by weight using a 5 liter Henschel mixer, blending for 15 minutes at a peripheral speed of 30 m / s, and then removing coarse particles using a sieve with an opening of 45 μm, A toner was prepared.

(Toner of Example 2: As hydrophobized inorganic fine particles, 40 parts by mass of decylsilane-treated external additive is used for 100 parts by mass of aluminum hydroxide particles)
As shown in Table 1, 100 parts of each of the toner base particles Y1, M1, C1, and K1 were hydrophobized with 40 parts by mass of decylsilane to 100 parts by mass of aluminum hydroxide particles (substantially hydrophobic treatment amount: 37.9 wt.%) And 1.5 parts by weight using a 5 liter Henschel mixer, blending for 15 minutes at a peripheral speed of 30 m / s, then removing coarse particles using a sieve with a mesh opening of 45 μm, A toner was prepared.

(Toner of Example 3: As hydrophobized inorganic fine particles, an external additive having been treated with 50 parts by mass of decylsilane with respect to 100 parts by mass of aluminum hydroxide particles)
As shown in Table 1, 100 parts of the toner base particles Y1, M1, C1, and K1 were each hydrophobized with 50 parts by mass of decylsilane (substantially hydrophobizing amount: 100 parts by mass). (45.5 wt%) and 1.5 parts by mass, using a 5 liter Henschel mixer, blending for 15 minutes at a peripheral speed of 30 m / s, and then removing coarse particles using a sieve with an opening of 45 μm, A toner was prepared.

(Example 4 Toner: As hydrophobized inorganic fine particles, an external additive having been treated with 60 parts by mass of decylsilane with respect to 100 parts by mass of aluminum hydroxide particles)
As shown in Table 1, 100 parts of each of the toner base particles Y1, M1, C1, and K1 were hydrophobized with 60 parts by mass of decylsilane (substantially hydrophobizing amount: 100 parts by mass of aluminum hydroxide particles). 49.6 wt%) and 1.5 parts by mass using a 5 liter Henschel mixer, blending for 15 minutes at a peripheral speed of 30 m / s, and then removing coarse particles using a sieve with an opening of 45 μm, A toner was prepared.

(Toner of Example 5: Using the aluminum hydroxide particles hydrophobized in Example 3 and using a crystalline resin as the final resin)
100 parts of the toner base particles C2 were treated with aluminum hydroxide particles (100 parts by mass of aluminum hydroxide particles subjected to hydrophobic treatment with 50 parts by mass of decylsilane (substantially hydrophobization amount: 45.5 wt%)). ) 1.5 parts by mass was added, blended for 15 minutes at a peripheral speed of 30 m / s using a 5 liter Henschel mixer, and then coarse particles were removed using a sieve having a mesh opening of 45 μm to prepare a toner. . Y1, M1, and K1 produced in Example 3 and the four colors C2 were used as a set, and the toner of Example 5 was obtained.

(Toner of Comparative Example 1: Use of aluminum hydroxide untreated product as inorganic fine particles)
To 100 parts of the toner base particles Y1, M1, C1, and K1, 1.5 parts by mass of the untreated aluminum hydroxide shown in Table 1 is added, and 15 parts at a peripheral speed of 30 m / s using a 5-liter Henschel mixer. After blending for a minute, coarse particles were removed using a sieve having an opening of 45 μm to prepare a toner.

(Toner of Comparative Example 2: As hydrophobized inorganic fine particles, an external additive subjected to 10 parts by mass of decylsilane treatment is used with respect to 100 parts by mass of silica)
100 parts of each of the toner base particles Y1, M1, C1, and K1 were each subjected to a hydrophobic treatment with 10 parts by mass of decylsilane (substantially hydrophobized amount: 100 parts by mass of silica). 7.8 wt%)) 1.5 parts by mass, and after blending for 15 minutes at a peripheral speed of 30 m / s using a 5 liter Henschel mixer, coarse particles are removed using a sieve with an opening of 45 μm. A toner was prepared.

(Toner of Comparative Example 3: As an inorganic fine particle subjected to hydrophobic treatment, an external additive having been treated with 10 parts by mass of decylsilane with respect to 100 parts by mass of titania)
100 parts of the toner base particles Y1, M1, C1, and K1 were each titania shown in Table 1 (100 parts by mass of titania subjected to hydrophobic treatment with 10 parts by mass of decylsilane (substantially hydrophobization amount: (8.9 wt%) 1.5 parts by mass, and after blending for 15 minutes at a peripheral speed of 30 m / s using a 5 liter Henschel mixer, coarse particles are removed using a sieve with a mesh opening of 45 μm, A toner was prepared.

(Toner of Comparative Example 4: As hydrophobized inorganic fine particles, an external additive subjected to 10 parts by mass of decylsilane treatment is used for 100 parts by mass of alumina)
100 parts of each of the toner base particles Y1, M1, C1, and K1 were each subjected to hydrophobization treatment with 10 parts by mass of decylsilane (substantially hydrophobization amount: 100 parts by mass of alumina). 9.3 wt%) 1.5 parts by mass, and after blending for 15 minutes at a peripheral speed of 30 m / s using a 5 liter Henschel mixer, coarse particles are removed using a sieve with an opening of 45 μm, A toner was prepared.

(Toner of Comparative Example 5: As externally treated hydrophobized inorganic fine particles, an external additive treated with 30 parts by mass of decylsilane is used with respect to 100 parts by mass of silica)
100 parts of each of the toner base particles Y1, M1, C1, and K1 are each silica shown in Table 1 (100 parts by mass of silica subjected to hydrophobic treatment with 30 parts by mass of decylsilane (substantially hydrophobic treatment amount: (16.2 wt%) 1.5 parts by mass, and after blending for 15 minutes at a peripheral speed of 30 m / s using a 5 liter Henschel mixer, coarse particles are removed using a sieve with an opening of 45 μm, A toner was prepared.

(Toner of Comparative Example 6: As an inorganic fine particle subjected to hydrophobic treatment, an external additive having been treated with 30 parts by mass of decylsilane with respect to 100 parts by mass of titania)
100 parts of the toner base particles Y1, M1, C1, and K1 were each titania shown in Table 1 (100 parts by mass of titania subjected to a hydrophobization treatment with 30 parts by mass of decylsilane (substantially hydrophobization amount: 14.8 wt%) 1.5 parts by mass, and after blending for 15 minutes at a peripheral speed of 30 m / s using a 5 liter Henschel mixer, coarse particles are removed using a sieve with an opening of 45 μm, A toner was prepared.

(Toner of Comparative Example 7: As an inorganic fine particle subjected to hydrophobic treatment, an external additive having been treated with 30 parts by mass of decylsilane with respect to 100 parts by mass of alumina)
100 parts of each of the toner base particles Y1, M1, C1, and K1 were each subjected to a hydrophobization treatment with 30 parts by mass of decylsilane (100 parts by mass of alumina (substantially hydrophobization treatment amount: 100 parts by mass of alumina)). 13.6 wt%) 1.5 parts by mass, and after blending for 15 minutes at a peripheral speed of 30 m / s using a 5 liter Henschel mixer, coarse particles are removed using a sieve with an opening of 45 μm, A toner was prepared.

(Toner of Comparative Example 8: As hydrophobized inorganic particles, an external additive treated with 30 parts by mass of dimethyl silicone oil is used with respect to 100 parts by mass of silica)
100 parts of each of the toner base particles Y1, M1, C1, and K1 were each subjected to a hydrophobic treatment with 30 parts by mass of dimethyl silicone oil (substantially a hydrophobic process with respect to 100 parts by mass of silica). (Amount: 28 wt%) 1.5 parts by mass, and after blending for 15 minutes at a peripheral speed of 30 m / s using a 5 liter Henschel mixer, coarse particles are removed using a sieve with an opening of 45 μm, A toner was prepared.

(Toner of Comparative Example 9: As externally treated hydrophobic fine particles, an external additive treated with 30 parts by mass of dimethyl silicone oil is used for 100 parts by mass of titania)
100 parts of the toner base particles Y1, M1, C1, and K1 are each titania shown in Table 1 (100 parts by mass of titania subjected to hydrophobic treatment with 30 parts by mass of dimethyl silicone oil (substantially hydrophobic process) (Amount: 29 wt%) 1.5 parts by mass, and after blending for 15 minutes at a peripheral speed of 30 m / s using a 5 liter Henschel mixer, remove coarse particles using a sieve with a mesh opening of 45 μm, A toner was prepared.

(Toner of Comparative Example 10: Uses external additive treated with 30 parts by mass of dimethyl silicone oil for 100 parts by mass of alumina as hydrophobized inorganic fine particles)
100 parts of each of the toner base particles Y1, M1, C1, and K1 were each subjected to hydrophobizing treatment with 30 parts by mass of dimethyl silicone oil (substantially hydrophobizing process with respect to 100 parts by mass of alumina). (Amount: 27 wt%) 1.5 parts by mass, and after blending for 15 minutes at a peripheral speed of 30 m / s using a 5 liter Henschel mixer, coarse particles are removed using a sieve with an opening of 45 μm, A toner was prepared.

  Each of the obtained toners was mixed with 100 parts of the carrier and 10 parts of the toner with a V-blender at 40 rpm for 20 minutes, and sieved with a sieve having an opening of 212 μm. Was made.

  Using each of the above developers, a DocuCentreColor400 (Fuji Xerox Co., Ltd.) remodeling machine (remodeling so that the fixing unit can be removed and unfixed images that do not pass through the fixing unit can be taken out during image quality evaluation) The evaluation was performed under the conditions shown in Table 3 below. The evaluation results are shown in Table 4 and Table 5 below.

(Evaluation details)
-Evaluation of actual machine image-
As an actual machine image output method, a gradation chart of four colors was used.
The gradation chart is
“A4 size chart (20%) for each color of image density (A)” and “A4 size chart (3% for each color of image density) (B)” were used. The image density is adjusted by the area ratio of the image portion. Each gradation chart has a solid portion, a halftone portion, and a background portion.

-Evaluation of charging characteristics-
(1) Output the gradation chart A under high temperature and high humidity (30 ° C./80%), collect the developer on the mag roll after 100 sheets and the developer on the mag roll after 5,000 sheets, and measure the charge Carried out.
(2) Output the gradation chart B under low temperature and low humidity (8 ° C / 10%), collect the developer on the mag roll after 100 sheets and the developer on the mag roll after 5,000 sheets, and measure the charge did.
The evaluation results are shown only for Cyan.

-Image quality evaluation-
After 100 and 5,000 sheets of gradation chart A output under high temperature and high humidity (30 ° C / 80%) and gradation chart B output under low temperature and low humidity (8 ° C / 10%) Using the output chart, the image density of the solid part and the fog of the background part were evaluated.
The evaluation results are shown only for Cyan.

-Cleaning-
A four-color photoconductor is provided with a cleaning blade having a rebound resilience of 30, and 30,000 gradation charts B are output under low temperature and low humidity (8 ° C./10%). The state of the wound was confirmed with a photochemical microscope.

  As the photoconductor, a new photoconductor used for DocuCenterColor was used as it was. Further, the surface of the photoreceptor was observed with a digital microscope VH-8000 manufactured by KEYENTH at a magnification of 3000 times.

(Evaluation methods)
[Charging evaluation]
Using a Faraday cage, the amount of charge was measured and the environmental difference was evaluated. When the environmental difference “(high temperature and high humidity charge amount) ÷ (low temperature and low humidity charge amount)” is 0.7 or more, “◯” is given, and when it is less than 0.7, “x” is given.

[Concentration evaluation standard]
The evaluation criteria for concentration were as follows.
The case where the concentration of X-Rite was 1.4 or more was rated as “◯”, and the case where it was less than 1.4 was evaluated as “×” (the concentration was insufficient).

[Background dirt evaluation criteria]
The case where the density of the X-Rite in the background portion was less than 0.2 was “◯”, and the case where it was 0.2 or more was “x” (stained).

[Surface evaluation of photoreceptor surface]
The surface of the photoreceptor was observed with a digital microscope VH-8000 manufactured by KEYENTH at a magnification of 3000 times. Images were printed out and the results of visual evaluation were shown. If there are no scratches or scars are almost marked as “○”, if there are many scratches as “X”,
The case where there were so many scratches that the image quality was affected was defined as “XX”.

(Evaluation results)
The aluminum hydroxide particles were not charged unless subjected to a hydrophobic treatment, and fogging occurred in both environments. Hydrophobized alumina and titania have low charge amount under high temperature and high humidity, and fogging occurred due to low charge especially over time. Silica sufficiently hydrophobized does not cause fogging under high temperature and high humidity, but the charge increased under low temperature and low humidity over time, resulting in a low concentration. With regard to the silicone oil-treated product as well, the electrification under low temperature and low humidity increased with time, resulting in a low concentration. A portion of alumina and titania showed scratches on the photoreceptor.

  In general, the hydrophobized aluminum hydroxide particles had a high charge level under high temperature and high humidity. Those obtained by hydrophobizing aluminum hydroxide particles generally had a good difference in charging environment, and a good image could be maintained for a long time without causing a problem of low density under low temperature and low humidity. The toner externally added with the hydrophobized aluminum hydroxide particles did not damage the surface of the photoreceptor. It was found that by applying hydrophobic treatment to aluminum hydroxide and increasing the treatment amount, the charge level under high temperature and high humidity increases. It was also found that there was an upper limit in the amount of treatment, but more than doubled treatment was possible compared to silica, titania and alumina having the same specific surface area. The toner using the crystalline resin showed a favorable charge level when using hydrophobized aluminum hydroxide, although the charge under high temperature and high humidity was slightly lower than the toner not using it.

Claims (1)

A toner for developing an electrostatic charge image, comprising toner mother particles containing a binder resin and a colorant, wherein one or more inorganic fine particles are added to the surface of the mother particles,
One kind of the inorganic fine particles is aluminum hydroxide particles,
An electrophotographic toner, wherein the aluminum hydroxide particles are hydrophobized with a treating agent that reacts with a hydroxyl group in the aluminum hydroxide particles.