JP2021071669A - Developer, developing device, process cartridge, and image forming apparatus - Google Patents

Abstract

To provide a developer that has high image density even after printing for a long period, and can prevent occurrence of carrier adhesion, scattering of toner, background fogging, and a ghost image, and wear of a photoreceptor.SOLUTION: A developer has toner and carrier. The toner includes strontium titanate particles each having particles including Si in its surface. A number average equivalent circle diameter of the particles including Si is 5 nm or more and 15 nm or less. The carrier includes a core material particle whose surface is covered with a coating layer including resin, and has a volume average particle diameter of 45 μm or more and 70 μm or less and bulk density of 2.10 g/cm3 or more and 2.50 g/cm3 or less.SELECTED DRAWING: None

Description

The present invention relates to a developer, a developing device, a process cartridge and an image forming device.

In the electrophotographic method, an electrostatic latent image is formed on a photoconductor such as a photoconductive substance, and a charged toner is adhered to the electrostatic latent image to form a toner image, and then the toner image is recorded as a recording medium. Transferred to and fixed to form an image.

In recent years, in combination with the increase in printing speed, there is a strong demand for improvement in the ability of carriers to apply charge to toner.

When a conventional carrier is used, the toner supplied to the developer whose toner has been consumed is not sufficiently triboelectrically charged, so that the toner is accumulated at the bottom of the developer carrier and the toner is developed on a blank sheet. There was a problem such as skin fog that would be damaged.

Therefore, it is required to control the charge amount of the toner to be constant.

Here, a toner containing strontium titanate particles is known (see, for example, Patent Document 1).

Further, carriers in which the surface of core material particles is coated with a coating layer containing a resin are known (see, for example, Patent Documents 2 to 5).

However, when printing for a long period of time, the components constituting the toner adhere to the carrier and the coating layer of the carrier is worn, so that carrier adhesion, toner scattering, background fog, ghost image are generated, and the image density is lowered. There was a problem of doing.

In addition, there is a problem that the photoconductor wears after printing for a long period of time.

An object of the present invention is to provide a developer capable of suppressing carrier adhesion, toner scattering, background fog, generation of ghost images, and wear of a photoconductor even when printed for a long period of time. To do.

One aspect of the present invention is the developer, which has a toner and a carrier, the toner contains strontium titanate particles having Si-containing particles on the surface, and the Si-containing particles have a diameter equivalent to a number average circle. The carrier is 5 nm or more and 15 nm or less, the surface of the core material particles is coated with a coating layer containing a resin, the volume average particle size is 45 μm or more and 70 μm or less, and the bulk density is 2.10 g / cm ³ More than 2.50 g / cm ³ or less.

According to the present invention, it is possible to provide a developer which has a high image density even when printed for a long period of time and can suppress carrier adhesion, toner scattering, background fog, generation of ghost images, and wear of a photoconductor. it can.

It is a figure which shows an example of the process cartridge of this embodiment. It is an SEM image of the toner 1 of an Example. It is a figure which shows the vertical band chart used when evaluating a ghost image.

Hereinafter, embodiments for carrying out the present invention will be described.

Since the following embodiments are preferred embodiments of the present invention, the present invention is not limited to the embodiments.

(Developer)
The developer of this embodiment has a toner and a carrier.

The toner contains strontium titanate particles having Si-containing particles (hereinafter referred to as Si-containing particles) on the surface, and the Si-containing particles have a diameter equivalent to a number average circle of 5 to 15 nm.

The surface of the core material particles of the carrier is coated with a coating layer containing a resin, the volume average particle size is 45 to 70 μm, and the bulk density is 2.10 to 2.50 g / cm ³ .

(Career)
The volume average particle size of the carrier is 45 to 70 μm, but is preferably 52 to 62 μm. If the volume average particle size of the carriers is less than 45 μm, edge carrier adhesion occurs when printing for a long period of time, and if it exceeds 70 μm, solid carrier adhesion and ghost images occur when printing for a long period of time, and the image density decreases. To do.

Here, the volume average particle size of the carrier can be measured using, for example, the Microtrack particle size distribution meter model HRA9320-X100 (manufactured by Nikkiso Co., Ltd.). The volume average particle size is calculated based on the volume-based particle size distribution, and the formula {Σ (Vi × di)} × {Σ (Vi)}.
It is represented by. Here, di is the representative particle size [μm] of the particles existing in each channel, and Vi is the volume of the particles existing in each channel. The channel has a length for dividing the range of the particle size in the particle size distribution map into equal parts, and 2 μm can be adopted in the present embodiment. Further, as the representative particle size of the particles existing in each channel, the lower limit value of the particle size of each channel can be adopted.

The bulk density of the carrier is 2.10 to 2.50 g / cm ³ , but it is preferably 2.55 to 2.50 g / cm ^3. If the bulk density of the carrier ^{is less than 2.10 g / cm 3} , edge carrier adhesion will occur after ^{long-term printing, and if it exceeds 2.50 g / cm 3} , solid carrier adhesion will occur after long-term printing. , The image density decreases.

The bulk density of the carrier can be measured, for example, according to the metal powder-apparent density test method (JIS-Z-2504).

Specifically, first, the carrier is naturally discharged from an orifice having a diameter of 2.5 mm, and the carrier is allowed to flow in until it overflows from ^{a 25 cm 3 stainless steel columnar container placed directly underneath, and then non-magnetic.} A horizontal spatula made of material can be used to measure by scraping the carrier along the top edge of the container in a single operation.

If it is difficult for the carrier to naturally flow out from the 2.5 mm diameter orifice, the carrier is naturally discharged from the 5 mm diameter orifice.

Next, the bulk density of the carriers is calculated by dividing the mass of the carriers that have flowed into the container by the volume of the container (25 cm ^3).

-Inorganic particles-
The coating layer may further contain inorganic particles. As a result, due to the spacer effect of the inorganic particles, the coating layer of the carrier is less likely to be worn even after printing for a long period of time.

The material constituting the inorganic particles is not particularly limited, but when a negatively charged toner is used, if a material having a positive charging property is used, the charging stability during long-term printing is improved.

Examples of the positively charged material include barium sulfate, zinc oxide, magnesium oxide, magnesium hydroxide, hydrotalcite and the like, and two or more of them may be used in combination. Among these, barium sulfate is preferable because it has a high charging ability for negatively charged toner, is white, and has little effect on the color of the toner even when it is removed from the coating layer.

-Resin-
Examples of the resin contained in the coating layer of the carrier include silicone resin, acrylic resin, and the like, and two or more kinds may be used in combination.

Acrylic resin has strong adhesiveness and low brittleness, and thus has excellent wear resistance. On the other hand, since the surface energy is high, the components constituting the toner may easily adhere to the coating layer. In that case, since the surface energy is low, this problem can be solved by using a silicone resin in which the components constituting the toner are hard to adhere in combination with the acrylic resin. Here, the silicone resin is inferior in abrasion resistance because it has weak adhesiveness and high brittleness. Therefore, it is important to obtain the properties of the acrylic resin and the silicone resin in a well-balanced manner. As a result, the components constituting the toner are less likely to adhere, and a coating layer having excellent wear resistance can be obtained.

The silicone resin is not particularly limited, and examples thereof include a straight silicone resin composed only of an organoshirosan bond, a modified silicone resin modified with alkyd, polyester, epoxy, acrylic, urethane and the like.

Examples of commercially available straight silicone resins include KR271, KR255, KR152 (above, manufactured by Shin-Etsu Chemical Co., Ltd.), SR2400, SR2406, SR2410 (above, manufactured by Toray Dow Corning Silicone) and the like.

The straight silicone resin can be used alone, but it is also possible to use a component that undergoes a cross-linking reaction, a component that adjusts the amount of charge, and the like in combination.

Commercially available products of the modified silicone resin include, for example, KR206 (alkyd modified), KR5208 (acrylic modified), ES1001N (epoxy modified), KR305 (urethane modified) (all manufactured by Shin-Etsu Chemical Co., Ltd.), SR2115 (epoxy modified), SR2110. (Alkyd modification) (above, made by Toray Dow Corning Silicone) and the like.

-Method of forming the coating layer-
When forming a coating layer on the surface of the core material particles, for example, a coating layer composition is applied to the surface of the core material particles.

Examples of the coating method of the coating layer composition include a spray-drying method, a dipping method, and a powder coating method. In order to form a uniform coating layer, it is preferable to use a fluidized bed coating device.

The coating layer composition preferably further contains a silane coupling agent. As a result, the inorganic particles can be stably dispersed in the coating layer.

Examples of the silane coupling agent include γ- (2-aminoethyl) aminopropyltrimethoxysilane, γ- (2-aminoethyl) aminopropylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane, and N-β-. (N-Vinylbenzylaminoethyl) -γ-aminopropyltrimethoxysilane hydrochloride, γ-glycidoxypropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, vinyltriacetoxy Silane, γ-chloropropyltrimethoxysilane, hexamethyldisilazane, γ-anilinopropyltrimethoxysilane, vinyltrimethoxysilane, octadecyldimethyl [3- (trimethoxysilyl) propyl] ammonium chloride, γ-chloropropylmethyldimethoxy Silane, methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, allyltriethoxysilane, 3-aminopropylmethyldiethoxysilane, 3-aminopropyltrimethoxysilane, dimethyldiethoxysilane, 1,3-divinyltetramethyldisilazane, Examples thereof include methacryloxyethyl dimethyl (3-trimethoxysilylpropyl) ammonium chloride, and two or more thereof may be used in combination.

Commercially available products of the silane coupling agent include, for example, AY43-059, SR6020, SZ6023, SH6026, SZ6032, SZ6050, AY43-310M, SZ6030, SH6040, AY43-026, AY43-031, sh6062, Z-6911, sz6300, sz6075, sz6079, sz6083, sz6070, sz6072, Z-6721, AY43-004, Z-6187, AY43-021, AY43-043, AY43-040, AY43-047, Z-6265, AY43-204M, AY43-048, Z-6403, AY43-206M, AY43-206E, Z6341, AY43-210MC, AY43-083, AY43-101, AY43-013, AY43-158E, Z-6920, Z-6940 (Toray Dow Corning Silicone) Made) and the like.

The mass ratio of the silane coupling agent to the silicone resin is preferably 0.1 to 10% by mass. When the mass ratio of the silane coupling agent to the silicone resin is 0.1% by mass or more, the adhesiveness between the core material particles and the inorganic particles and the silicone resin is improved, so that the coating layer falls off even after printing for a long period of time. If it is less than 10% by mass, it becomes difficult for the components constituting the toner to adhere to the carrier even after printing for a long period of time.

-Core particle-
The material constituting the core material particles is not particularly limited as long as it is a magnetic material, but ferromagnetic metals such as iron and cobalt; iron oxides such as magnetite, hematite and ferrite; various alloys and compounds; these magnetic materials Examples include dispersed resin particles. Among these, Mn-based ferrite, Mn-Mg-based ferrite, and Mn-Mg-Sr-based ferrite are preferable from the viewpoint of environmental consideration.

(toner)
The toner contains strontium titanate particles having Si-containing particles having a diameter equivalent to a number average circle of 5 to 15 nm on the surface, and if necessary, particles other than strontium titanate particles (hereinafter referred to as other particles) are further added. It may be included.

The toner preferably has strontium titanate particles (and other particles) on the surface of the parent particles as an external additive. At this time, the negative chargeability of the strontium titanate particles is improved, and the weakly charged toner and the positively charged toner are reduced, so that the charge rising property of the toner is improved.

-Si-containing particles-
Examples of the material constituting the Si-containing particles include sodium silicate, silica and the like.

It can be confirmed by SEM-EDS (energy dispersive X-ray analyzer-scanning electron microscope) measurement that the Si-containing particles are present on the surface of the strontium titanate particles.

The diameter equivalent to the number average circle of the Si-containing particles is 5 to 15 nm, preferably 7 to 13 nm, and more preferably 8 to 10 nm. If the diameter equivalent to the number average circle of the Si-containing particles is less than 5 nm, the photoconductor wears, and if it exceeds 15 nm, toner scattering and background fog occur after long-term printing.

The number average circle-equivalent diameter of the Si-containing particles is, for example, binary values obtained by arbitrarily extracting 130 Si-containing particles from an image observed by a scanning electron microscope (SEM) and using image processing software. It can be obtained by converting and calculating the equivalent circle diameter and then averaging them.

-Strontium titanate particles-
Strontium titanate particles having Si-containing particles on the surface can be obtained by adding a material for Si-containing particles when synthesizing strontium titanate particles by a room temperature wet method, as will be described later.

Examples of the shape of the strontium titanate particles include a spherical shape and a needle shape.

The strontium titanate particles may be single particles or particles in which a plurality of particles are aggregated.

The diameter equivalent to the number average circle of the primary particles of the strontium titanate particles is preferably 20 to 40 nm. When the diameter equivalent to the number average circle of the primary particles of the strontium titanate particles is 20 nm or more and 40 nm or less, background fog is less likely to occur even after long-term printing.

For the number average circle equivalent diameter of the primary particles of the strontium titanate particles, for example, 130 primary particles of the strontium titanate particles are arbitrarily extracted from an image observed by a scanning electron microscope (SEM). It can be obtained by binarizing the particles using image processing software, calculating the equivalent circle diameter, and then averaging them.

The molar ratio of Si to Ti of the strontium titanate particles is preferably 1.0 to 10.0, more preferably 2.0 to 9.0, and 3.0 to 7.0. Is more preferable, and 4.0 to 6.0 is particularly preferable. When the molar ratio of Si to Ti of strontium titanate particles is 1.0 or more, background fog is less likely to occur even after long-term printing, and when it is 10.0 or less, even after long-term printing, Toner scattering is less likely to occur.

The molar ratio of Si to Ti of strontium titanate particles is determined from the ratio of the peak intensity of Si to the peak intensity of Ti in the strontium titanate particles, based on the peak intensity of carbon by, for example, X-ray analysis of SEM-EDS. Can be measured.

The BET specific surface area of the strontium titanate particles ^{is preferably 50 m 2} / g or more. When the BET specific surface area of the strontium titanate particles is 50 m ² / g or more, toner scattering is less likely to occur even after printing for a long period of time.

The BET specific surface area of the strontium titanate particles can be measured using, for example, Gemini 2375 (manufactured by MICROMETORICS INSTRUMENT).

The mass ratio of the strontium titanate particles to the parent particles is preferably 0.4 to 4.0%, more preferably 1.0 to 2.2%. When the mass ratio of the strontium titanate particles to the parent particles is 0.4% or more, the fluidity and cohesiveness of the toner are improved, the image quality of the half image is improved, and white spots in the image occur due to the aggregation of the toner. It becomes difficult. When the mass ratio of the strontium titanate particles to the parent particles is 4.0% or less, the low temperature fixability of the toner is improved.

-Synthesis of strontium titanate particles-
Examples of the method for synthesizing strontium titanate particles having Si-containing particles on the surface include a room temperature wet method and the like.

Specifically, after mixing a mineral acid defibrated product, which is a hydrolysis product of a titanium compound, as a source of Ti, and a water-soluble compound, which is a source of Sr, a material for Si-containing particles is further added. Strontium titanate particles can be obtained by reacting the mixed solution obtained by mixing while adding an alkaline aqueous solution at a temperature of 50 ° C. or higher and lower than the boiling point.

Examples of the mineral acid defibrated product include metatitanic acid and the like.

Examples of the water-soluble compound include strontium chloride, strontium nitrate, strontium hydroxide and the like.

Examples of the alkaline aqueous solution include an aqueous solution of an alkali metal hydroxide such as sodium hydroxide.

Examples of the material for Si-containing particles include sodium silicate, silica and the like.

-Other particles-
Examples of materials constituting other particles include silica, titanium oxide, barium titanate, magnesium titanate, calcium titanate, alumina, iron oxide, copper oxide, zinc oxide, tin oxide, silica sand, clay, and mica. Silica ash, silica soil, chromium oxide, cerium oxide, red iron oxide, antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silicon carbide, silicon nitride, etc. can be mentioned, and two or more of them can be used together. You may.

The other particles may be surface-treated with a surface treatment agent in order to improve the hydrophobicity of the surface and improve the fluidity and chargeability under high humidity.

Examples of the surface treatment agent include an alkylsilane coupling agent, a fluorine-containing silane coupling agent, a silylating agent, an organic titanate-based coupling agent, an aluminum-based coupling agent, a silicone oil, and a modified silicone oil.

The mass ratio of the other particles to the parent particles is preferably 0.4 to 4.0%, more preferably 1.0 to 2.2%. When the mass ratio of the other particles to the parent particles is 0.4% or more, the fluidity and cohesiveness of the toner can be improved, the image quality of the half image is improved, and the white spots in the image due to the aggregation of the toner It is less likely to occur. When the mass ratio of the other particles to the parent particles is 4.0% or less, the low temperature fixability of the toner is improved.

− Maternal particles −
The base particles contain a resin and a wax, and may further contain a component other than the resin and the wax (hereinafter, referred to as another component), if necessary.

The volume average particle size of the parent particles is preferably 3.0 to 8.0 μm. When the volume average particle diameter of the matrix particles is 3.0 μm or more, the components constituting the toner are less likely to adhere to the carrier, and when it is 8.0 μm or less, the resolution and image quality of the image are improved.

The content of the particles having a size of 5.0 μm or less in the mother particles is preferably 20 to 40% by number.

Examples of the shape of the matrix particles include a spherical shape and a needle shape.

The parent particle may be a single particle or a particle in which a plurality of particles are aggregated.

The circularity of the parent particles is preferably 0.92 to 0.98.

Examples of the structure of the mother particle include a single structure, a core-shell structure, and the like.

-Resin-
Examples of the resin include a shrink-polymerized resin such as polyester, polyamide and polyester polyamide copolymer, an addition-polymerized resin such as vinyl resin, and two or more thereof may be used in combination.

Polyester is obtained by polycondensation of a polyhydric alcohol and a polybasic acid.

Examples of the polyhydric alcohol include glycols such as ethylene glycol, diethylene glycol, triethylene glycol and propylene glycol, alicyclic compounds having two hydroxyl groups such as 1,4-bis (hydroxymethyl) cyclohexane, and bisphenol A. And the like, dihydric phenol compounds and the like can be mentioned.

The polyhydric alcohol may have three or more hydroxyl groups.

Examples of the polybasic acid include divalent carboxylic acids such as maleic acid, fumaric acid, phthalic acid, isophthalic acid, terephthalic acid, succinic acid and malonic acid, 1,2,4-benzenetricarboxylic acid, 1,2,5. −benzenetricarboxylic acid, 1,2,4-cyclohexanetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxy-2-methylenecarboxypropane, 1, Examples thereof include trivalent or higher valent carboxylic acids such as 2,7,8-octanetetracarboxylic acid, and two or more thereof may be used in combination.

Polyamide is obtained by polycondensation of a polyvalent amine and a polybasic acid, or by polycondensation of an aminocarboxylic acid.

The polyester polyamide copolymer can be obtained by polycondensation of a polyhydric alcohol, a polyhydric amine and a polybasic acid, or by polycondensation of a polyhydric alcohol, a polybasic acid and an aminocarboxylic acid.

Examples of the polyvalent amine include ethylenediamine, pentamethylenediamine, hexamethylenediamine, phenylenediamine, triethylenetetramine and the like, and two or more of them may be used in combination.

Examples of the aminocarboxylic acid include 6-aminocaproic acid, ε-caprolactam and the like, and two or more of them may be used in combination.

The glass transition temperature of the polycondensation resin is preferably 55 ° C. or higher, more preferably 57 ° C. or higher, from the viewpoint of heat-resistant storage of the toner.

The vinyl-based resin is obtained by addition polymerization of the vinyl-based monomer.

Examples of the vinyl-based monomer include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-ethylstyrene, vinylnaphthalene; and ethylene-based non-ethylene such as ethylene, propylene, butylene, and isobutylene. Saturated monoolefins; vinyl esters such as vinyl chloride, vinyl bromide, vinyl acetate, vinyl formate; acrylic acid, methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, tert-butyl acrylate, Amyl Acrylic Acid, Acrylic Acid, Methyl Methacrylic Acid, Ethyl Methacrylate, n-propyl Methacrylate, Isopropyl Methacrylate, tert-Butyl Methacrylate, Amyl Methacrylate, Stearyl Methacrylate, methoxyethyl Methacrylate, Glycidyl Methacrylate, Glycyl Methacrylic Acid Ethylene monocarboxylic acids such as phenyl, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate or esters thereof; ethylenic monocarboxylic acid substituents such as acryliconitrile, methacrylic acid, acrylamide; ethylenic dicarboxylic acids such as dimethyl maleate or Substitutes thereof: vinyl ketones such as vinyl methyl ketone and the like, and two or more thereof may be used in combination.

When the vinyl-based monomer is addition-polymerized, a cross-linking agent can be added if necessary.

Examples of the cross-linking agent include divinylbenzene, divinylnaphthalene, polyethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol diacrylate, dipropylene glycol dimethacrylate, polypropylene glycol dimethacrylate, diallyl phthalate, and the like. May be used together.

The mass ratio of the cross-linking agent to the vinyl-based monomer is preferably 0.05 to 15%, more preferably 0.1 to 10%. When the mass ratio of the cross-linking agent to the vinyl-based monomer is 0.05% or more, the heat-resistant storage stability of the toner is improved, and when it is 15% or less, the low-temperature fixability of the toner is improved.

When addition-polymerizing a vinyl-based monomer, it is preferable to use a polymerization initiator.

Examples of the polymerization initiator include azo-based or diazo-based polymerization initiators such as 2,2'-azobis (2,4-dimethylvaleronitrile) and 2,2'-azobisisobutyronitrile, and benzoyl peroxide. Examples thereof include peroxide polymerization initiators such as methyl ethyl ketone peroxide and 2,4-dichlorobenzoyl peroxide, and two or more of them may be used in combination.

The mass ratio of the polymerization initiator to the vinyl-based monomer is preferably 0.05 to 15%, more preferably 0.5 to 10%.

The resin may be a non-linear resin having a non-linear structure, or may be a linear resin having a linear structure. Here, the non-linear resin means a resin having a crosslinked structure, and the linear resin means a resin having no crosslinked structure.

As the resin, a non-linear resin and a linear resin can be used in combination.

As the resin, a hybrid resin in which a polycondensation resin and an addition polymerization resin are chemically bonded can be used. As a result, the dispersibility of the wax is improved, and as a result, the heat-resistant storage stability of the toner is improved, and the filming of the photoconductor is less likely to occur.

The hybrid resin is obtained by polycondensation and addition polymerization using a bireactive compound capable of polycondensation and addition polymerization.

Examples of the bireactive compound include fumaric acid, acrylic acid, methacrylic acid, maleic acid, dimethyl fumarate and the like.

The mass ratio of the bireactive compound to the monomer of the addition polymerization resin is preferably 1 to 25%, more preferably 2 to 10%. When the mass ratio of the bireactive compound to the monomer of the addition polymerization resin is 1% or more, the dispersibility of the wax in the parent particles is improved, and when it is 25% or less, the resin is less likely to gel.

When synthesizing the hybrid resin, it is not necessary to proceed and complete the polycondensation and the addition polymerization at the same time, and the respective reaction temperatures and times can be selected to independently proceed and complete the polycondensation and the addition polymerization. ..

For example, in a reaction vessel, a mixture of a vinyl-based monomer and a polymerization initiator is dropped and mixed in a mixture of a polyhydric alcohol and a polybasic acid to complete the addition polymerization of the vinyl-based monomer, and then the reaction is carried out. The temperature is raised to complete the polycondensation of the polyhydric alcohol and the polybasic acid. As a result, polycondensation and addition polymerization can proceed independently in the reaction vessel, and the polyester and the vinyl resin can be effectively bonded.

Examples of the resin other than the above include polyurethane, silicone resin, ketone resin, petroleum-based resin, hydrogenated petroleum-based resin, and the like.

-Wax-
Examples of the wax include ester wax, polyolefin wax, long-chain hydrocarbon and the like, and two or more kinds may be used in combination. Among these, ester wax is preferable, and synthetic monoester wax is more preferable.

Examples of the ester wax include polyalkanoic acid ester and polyalkanol ester.

Examples of the polyalkanoic acid ester include carnauba wax, montan wax, trimethylolpropane tribehenate, pentaerythritol tetrabehenate, pentaerythritol diacetate dibehenate, glycerin tribehenate, and 1,18-octadecane. Examples include diol distearate.

Examples of the polyalkanol ester include tristearyl trimellitic acid and distearyl maleate.

Synthetic monoester waxes are synthesized, for example, from long-chain linear saturated fatty acids and long-chain linear saturated alcohols.

Long-chain linear saturated fatty acid has the general formula C _n H _2n + 1 COOH
It is represented by, and n is preferably about 5 to 28.

Furthermore, long chain linear saturated alcohols of the general formula C _n H _2n + 1 OH
It is represented by, and n is preferably about 5 to 28.

Examples of long-chain linear saturated fatty acids include capric acid, undecic acid, lauric acid, tridecyl acid, myristic acid, pentadecic acid, palmitic acid, heptadecanoic acid, tetradecanoic acid, stearic acid, nonadecanoic acid, aramonic acid, bechenic acid, Examples thereof include lignoseric acid, serotic acid, heptacosanoic acid, montanic acid, and myristic acid.

Examples of long-chain linear saturated alcohols include amyl alcohol, hexyl alcohol, heptyl alcohol, octyl alcohol, capryl alcohol, nonyl alcohol, decyl alcohol, undecyl alcohol, lauryl alcohol, tridecyl alcohol, myristyl alcohol, and pentadecyl. Examples thereof include alcohols, cetyl alcohols, heptadecyl alcohols, stearyl alcohols, nonadesyl alcohols, eicosyl alcohols, ceryl alcohols, and heptadecanools.

The long-chain linear saturated fatty acid and the long-chain linear saturated alcohol may be substituted with a substituent such as a lower alkyl group, an amino group or a halogen.

The equivalent circle diameter of the ester wax in the cross section of the toner is preferably 0.1 to 0.5 μm. When the equivalent circle diameter of the ester wax in the cross section of the toner is 0.1 μm or more, the background fog is less likely to occur even after long-term printing, and when it is 0.5 μm or less, the background even after long-term printing. Fogging is less likely to occur, and the photoconductor is less likely to wear.

The circle-equivalent diameter of the ester wax in the cross section of the toner can be measured from the image of the cross section of the toner observed by SEM after the cross section of the toner is dyed with ruthenium.

When the toner contains polyester, the maximum height of the peak derived from the ester wax in the FT-IR spectrum (Fourier transform infrared absorption spectrum) obtained by measuring the toner by the ATR method (total reflection method) is W. If the maximum height of the peak derived from polyester is R, the formula 0.05 ≦ W / R ≦ 0.14
It is preferable to satisfy. When the W / R is 0.05 or more, the photoconductor is less likely to be worn even when printed for a long period of time, and when it is 0.14 or less, the background fog is less likely to occur even when printed for a long period of time.

The maximum height of the peak means the height of the peak at which the height from the baseline is the maximum.

The content of the wax in the toner is preferably 0.5 to 20% by mass, more preferably 2 to 10% by mass. When the content of wax in the toner is 0.5% by mass or more, the high temperature offset resistance and low temperature fixability of the toner are improved, and when it is 20% by mass or less, the heat storage stability of the toner is improved.

-Other ingredients-
Examples of other components include colorants, charge control agents, cleanability improvers, magnetic materials, and the like.

--Colorant ---
Examples of the colorant include carbon black, niglosin dye, iron black, naphthol yellow S, Hansa yellow (10G, 5G, G), cadmium yellow, yellow iron oxide, yellow clay, yellow lead, titanium yellow, polyazo yellow, and the like. Oil Yellow, Hansa Yellow (GR, A, RN, R), Pigment Yellow L, Benzidine Yellow (G, GR), Permanent Yellow (NCG), Balkan Fast Yellow (5G, R), Tartragin Lake, Kinolin Yellow Lake, Anthracan Yellow BGL, Isoindolinon Yellow, Bengala, Lead Tan, Lead Zhu, Cadmium Red, Cadmium Mercuri Red, Antimon Zhu, Permanent Red 4R, Para Red, Faise Red, Parachloro Ortho Nitroaniline Red, Resole Fast Scarlet G, Brilliant Fast Scarlet, Brilliant Carmin BS, Permanent Red (F2R, F4R, FRL, FRLL, F4RH), Fast Scarlet VD, Belkan Fast Rubin B, Brilliant Scarlet G, Resole Rubin GX, Permanent Red F5R, Brilliant Carmin 6B, Pigment Scarlet 3B Bordeaux 5B, Truisin Maroon, Permanent Bordeaux F2K, Helio Bordeaux BL, Bordeaux 10B, Bonmaroon Light, Bonmaroon Medium, Eosin Lake, Rhodamin Lake B, Rhodamin Lake Y, Alizarin Lake, Thioinjigo Red B, Thioinjigo Maroon, Oil Red, Kinakridon Red, Pyrazolon Red, Polyazo Red, Chrome Vermilion, Benzidine Orange, Perinon Orange, Oil Orange, Cobalt Blue, Cerulean Blue, Alkaline Blue Lake, Peacock Blue Lake, Victoria Blue Lake, Metallic Phtalocyanin Blue, Phtalocyanin Blue, Fast Sky Blue, Indan Slen Blue (RS, BC), Indigo, Ultramarine, Navy Blue, Anthraquinone Blue, Fast Violet B, Methyl Violet Lake, Cobalt Purple, Manganese Purple, Dioxane Violet, Anthraquinone Violet, Chrome Green, Zink Green, Oxidation Chrome, Pyrigian, Emerald Green, Pigment Green B, Naftor Green B, Green Gold, Acid Green Lake, Malakite Green Lake, Phtalocyanin Green, Anthracine Yellow , Titanium oxide, zinc oxide, lithobon and the like.

The content of the colorant in the toner is preferably 1 to 15% by mass, more preferably 3 to 10% by mass.

--Charge control agent ---
Examples of the charge control agent include niglosin dyes, triphenylmethane dyes, chromium-containing metal complex dyes, molybdic chelate pigments, rhodamine dyes, alkoxy amines, and quaternary ammonium salts (including fluorine-modified quaternary ammonium salts). ), Alkylamide, phosphorus alone or compound, tungsten alone or compound, fluorine-based surfactant, salicylate metal salt, salicylic acid derivative metal salt and the like.

The content of the charge control agent in the toner is preferably 0.1 to 10% by mass, more preferably 0.2 to 5% by mass. When the content of the charge control agent in the toner is 0.1% by mass or more, the charge rising property of the toner is improved, and when it is 10% by mass or less, the image density is high.

--Cleaning property improver ---
Examples of the cleaning property improving agent include fatty acid metal salts such as zinc stearate, calcium stearate, and stearic acid, and polymer particles produced by soap-free emulsion polymerization such as polymethylmethacrylate particles and polystyrene particles.

The volume average particle size of the polymer particles is preferably 0.01 to 1 μm.

(Toner manufacturing method)
Examples of the toner manufacturing method include a pulverization method and a polymerization method.

-Grinding method-
For example, the resin, wax, and if necessary, other components are mixed using a mixer or the like, and then kneaded using a kneader such as a hot roll or an extruder. The obtained kneaded product is cooled and solidified, pulverized using a pulverizer such as a jet mill, and then classified to obtain parent particles. Toner is obtained by mixing the matrix particles, strontium titanate particles, and other particles, if necessary.

-Polymerization method-
Examples of the polymerization method include a massive polymerization method, a solution polymerization method, an emulsion polymerization method, a suspension polymerization method and the like.

(Replenishing developer)
The developer of this embodiment can be used as a supplementary developer.

By replenishing the replenishing developer while discharging the surplus developing agent in the developing apparatus, stable image quality can be obtained over a long period of time. That is, by replacing the deteriorated carriers in the developing apparatus with the non-deteriorated carriers in the replenishing developer, the amount of charge can be maintained for a long period of time, and stable image quality can be obtained.

The replenishing developer is particularly effective when printing a high image area.

Generally, when printing a high image area, it is difficult to maintain the charge amount of the carrier because the components constituting the toner tend to adhere to the carrier.

Therefore, when a replenishing developer is used, the amount of replenishment of carriers increases when printing a high image area, so that the deteriorated carriers are frequently replaced. As a result, stable image quality can be obtained over a long period of time.

The mass ratio of the toner to the carrier in the replenishing developer is preferably 2 to 50. When the mass ratio of the toner to the carrier in the replenishing developer is 2 or more, the image density is high, and when it is 50 or less, the image quality is improved.

(Image forming device)
The image forming apparatus of the present embodiment is formed on the photoconductor, a charging means for charging the photoconductor, an exposure means for irradiating the charged photoconductor with exposure light to form an electrostatic latent image, and a photoconductor. A developing means for developing an electrostatic latent image with the developer of the present embodiment to form a toner image, a transfer means for transferring a toner image formed on a photoconductor to a recording medium, and a transfer means for transferring the toner image to a recording medium. It has a fixing means for fixing the toner image.

The image forming apparatus of the present embodiment may further include static elimination means, cleaning means, recycling means, control means, and the like, if necessary.

(Process cartridge)
The process cartridge of the present embodiment has a photoconductor and a developing means for developing an electrostatic latent image formed on the photoconductor with the developer of the present embodiment to form a toner image, and forms an image. It is removable to the main body of the device.

FIG. 1 shows an example of the process cartridge of the present embodiment.

In the process cartridge (10), the photoconductor (11), the charging device (12) for charging the surface of the photoconductor (11), and the electrostatic latent image formed on the surface of the photoconductor (11) are subjected to the present implementation. A developing device (13) that develops with the developer of the form to form a toner image, and a toner image formed on the photoconductor (11) is transferred to a recording medium and then remains on the photoconductor (11). A cleaning device (14) for removing the toner is integrally supported.

The process cartridge (10) is removable from the main body of an image forming apparatus such as a copying machine or a printer.

Hereinafter, a method of forming an image by using an image forming apparatus equipped with a process cartridge (10) will be described.

First, the photoconductor (11) is rotationally driven at a predetermined peripheral speed, and the surface of the photoconductor (11) is uniformly charged to a predetermined positive or negative potential by the charging device (12). Next, exposure light is irradiated to the surface of the charged photoconductor (11) from an exposure apparatus such as a slit exposure type exposure apparatus or an exposure apparatus that scans and exposes with a laser beam, and an electrostatic latent image is formed. Further, the electrostatic latent image formed on the surface of the photoconductor (11) is developed by the developing apparatus (13) using the developing agent of the present embodiment to form a toner image. Next, the toner image formed on the surface of the photoconductor (11) is transferred from the paper feed unit between the photoconductor (11) and the transfer device in synchronization with the rotation of the photoconductor (11). Transferred to paper. Further, the transfer paper on which the toner image is transferred is separated from the surface of the photoconductor (11), introduced into the fixing device, fixed, and then printed out as a copy to the outside of the image forming device. Toner. On the other hand, the surface of the photoconductor (11) to which the toner image is transferred is cleaned by removing the residual toner by the cleaning device (14). The cleaned photoconductor (11) is repeatedly used for image formation after being statically eliminated by the static elimination device.

Hereinafter, examples of the present invention will be described, but the present invention is not limited to the examples.

(Synthesis of non-linear polyester A)
A flask equipped with a stainless steel stirring rod, a flow-down condenser, a nitrogen gas introduction tube, and a thermometer contains 9.0 mol of fumaric acid, 3.5 mol of trimellitic anhydride, and 5.5 mol of bisphenol A (2,2) propylene oxide. , 3.5 mol of ethylene oxide of bisphenol A (2,2) was added, and then shrink-polymerized with stirring at 230 ° C. under a nitrogen gas stream to obtain a non-linear polyester A.

The softening temperature, glass transition temperature, and weight average molecular weight of the non-linear polyester A were 145.1 ° C, 61.5 ° C, and 82,000, respectively.

<Softening temperature>
Using a high-grade flow tester CFT-500D (manufactured by Shimadzu Corporation), a 1 cm ³ non-linear polyester A is heated at a heating rate of 6 ° C./min based on JIS K72101, and 20 kg / by a plunger. A load of cm ² was applied and extruded from a nozzle having a diameter of 1 mm and a length of 1 mm. Here, when the amount of descent of the plunger is plotted against the temperature and the maximum value of the amount of descent of the plunger is h, the temperature corresponding to h / 2, that is, half of the non-linear polyester A flows out. The temperature was defined as the softening temperature.

<Glass transition temperature>
Using a differential scanning calorimeter DSC-60 (manufactured by Shimadzu Corporation), the temperature of the non-linear polyester A is raised from 25 ° C. to 200 ° C. at 10 ° C./min based on JIS K7121-1987, and then 10 ° C./min. After cooling to 25 ° C. at a temperature lowering rate, the temperature was raised at a temperature rising rate of 10 ° C./min. Here, when the difference in height between the baseline before the non-linear polyester A of the DSC curve undergoes the glass transition and the height of the baseline after the non-linear polyester A undergoes the glass transition is h, it corresponds to h / 2. The temperature was taken as the glass transition temperature.

<Weight average molecular weight>
The weight average molecular weight of the non-linear polyester A was measured using a GPC measuring device HLC-8220 GPC (manufactured by Tosoh) and a column TSKgel SuperHZM-H 15 cm triplet (manufactured by Tosoh). Specifically, after stabilizing the column in a heat chamber at 40 ° C., 50 μL to 200 μL of a solution of the non-linear polyester A in tetrahydrofuran (THF) is injected into the column at a flow rate of 1 mL / min, and the non-linear polyester is poured. The weight average molecular weight of A was measured. At this time, the weight average molecular weight of the non-linear polyester A was determined from the relationship between the logarithmic value of the calibration curve prepared using several types of monodisperse polystyrene standard samples and the count number. An RI (refractive index) detector was used as the detector.

As a standard sample of monodisperse polystyrene, the weight average molecular weights are 6 × 10 ² , 2.1 × 10 ³ , 4 × 10 ³ , 1.75 × 10 ⁴ , 5.1 × 10 ⁴ , 1.1 × 10. ^{Samples of 5} , 3.9 × 10 ⁵ , 8.6 × 10 ⁵ , 2 × 10 ⁶ , and 4.48 × 10 ⁶ (manufactured by Pressure Chemical or manufactured by Tosoh) were used.

(Synthesis of linear polyester B)
7.0 mol of terephthalic acid, 2.5 mol of trimellitic anhydride, 5.5 mol of bisphenol A (2,2) propylene oxide in a flask equipped with a stainless steel stirring rod, a flow-down condenser, a nitrogen gas introduction tube, and a thermometer. , 3.5 mol of bisphenol A (2,2) ethylene oxide was added and then polycondensed under a nitrogen gas stream at 230 ° C. to obtain linear polyester B.

The softening temperature, glass transition temperature, and weight average molecular weight of the linear polyester B were 102.8 ° C, 61.2 ° C, and 8,000, respectively.

The softening temperature, glass transition temperature, and weight average molecular weight of the linear polyester B were measured in the same manner as in the non-linear polyester A.

(Synthesis of hybrid resin C)
Chemical formula (1) in hybrid resin C in a 5 liter autoclave with a distillation column

で表されるポリオキシプロピレン（２．２）−２，２−ビス（４−ヒドロキシフェニル）プロパン（以下、ＢＰＡ−ＰＯという）由来の構成単位、セバシン酸由来の構成単位が、それぞれ４５ｍｏｌ％、３０ｍｏｌ％となるように配合されたＢＰＡ−ＰＯとセバシン酸の混合物４，０００ｇ、酸化ジブチルスズ５ｇを入れた後、窒素ガス気流下、２３０℃で６時間縮重合させた後、１６０℃まで冷却した。次に、ハイブリッド樹脂Ｃ中のスチレン由来の構成単位、アクリル酸由来の構成単位が、それぞれ１５ｍｏｌ％、１０ｍｏｌ％となるように配合されたスチレンと、アクリル酸と、ジ−ｔｅｒｔ−ブチルペルオキシドの混合液２５ｇを１６０℃で１時間撹拌しながら添加し、１６０℃で１時間付加重合させた後、１８０℃で縮重合させ、ハイブリッド樹脂Ｃを得た。

The constituent units derived from polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane (hereinafter referred to as BPA-PO) represented by, and the constituent units derived from sebacic acid are 45 mol%, respectively. After adding 4,000 g of a mixture of BPA-PO and sebacic acid and 5 g of dibutyltin oxide compounded so as to have a concentration of 30 mol%, the polycondensation was carried out at 230 ° C. for 6 hours under a nitrogen gas stream, and then cooled to 160 ° C. .. Next, a mixture of styrene, acrylic acid, and di-tert-butylperoxide, which are blended so that the styrene-derived structural unit and the acrylic acid-derived structural unit in the hybrid resin C are 15 mol% and 10 mol%, respectively. 25 g of the liquid was added at 160 ° C. for 1 hour with stirring, addition polymerization was carried out at 160 ° C. for 1 hour, and then polycondensation was carried out at 180 ° C. to obtain a hybrid resin C.

(Synthesis of strontium titanate particles A)
After the metatitanic acid obtained by the sulfuric acid method was desulfurized and bleached, a 5N sodium hydroxide aqueous solution was added to 320 g of metatitanic acid so that the pH was 9.0, and the desulfurization treatment was performed. Next, 2N hydrochloric acid was added so that the pH became 6.2, the mixture was filtered, and then washed with water to obtain a washed cake.

Water was added to the obtained washed cake _{to obtain a titanium oxide slurry having a TiO 2} content of 2.1 mol / L, and then 2N hydrochloric acid was added so that the pH became 1.4, and the cake was glutinated. A _{deflated titanium hydroxide slurry having a TiO 2} content of 1.88 mol / L was obtained.

After adding an aqueous solution of strontium chloride so that the molar ratio of Sr to Ti is 1.25, the molar ratio of Si to Ti is 5 to the obtained deflated titanium hydroxide slurry, so that sodium silicate is used. Was added to _{adjust the concentration of TiO 2} to 0.94 mol / L, and heat treatment was performed at 90 ° C. Next, 560 mL of a 10N aqueous sodium hydroxide solution was added over 1 hour, and then the mixture was stirred at 95 ° C. for 1 hour to obtain a slurry.

After cooling the obtained slurry to 50 ° C., 2N hydrochloric acid was added until the pH reached 5.0, and the mixture was stirred for 1 hour to obtain a precipitate.

The obtained precipitate was decanted and filtered, and then dried in the air at 120 ° C. for 10 hours to obtain strontium titanate particles A.

When the strontium titanate particles A were analyzed using SEM-EDS X-ray analysis, sodium silicate particles were present on the surface of the strontium titanate particles A, and sodium silicate was also inside the strontium titanate particles A. Particles were present.

(Synthesis of strontium titanate particles B)
Strontium titanate particles B were obtained in the same manner as the strontium titanate particles A except that sodium silicate was added so that the molar ratio of Si to Ti was 1.

When the strontium titanate particles B were analyzed using SEM-EDS X-ray analysis, sodium silicate particles were present on the surface of the strontium titanate particles B, and sodium silicate was also inside the strontium titanate particles B. Particles were present.

(Synthesis of strontium titanate particles C)
Strontium titanate particles C were obtained in the same manner as the strontium titanate particles A except that sodium silicate was added so that the molar ratio of Si to Ti was 11.

When the strontium titanate particles C were analyzed using SEM-EDS X-ray analysis, sodium silicate particles were present on the surface of the strontium titanate particles C, and sodium silicate was also inside the strontium titanate particles C. Particles were present.

(Synthesis of strontium titanate particles D)
Strontium titanate particles D were obtained in the same manner as the strontium titanate particles A except that sodium silicate was added and heat-treated at 80 ° C. so that the molar ratio of Si to Ti was 4/3.

When the strontium titanate particles D were analyzed using SEM-EDS X-ray analysis, sodium silicate particles were present on the surface of the strontium titanate particles D, and sodium silicate was also inside the strontium titanate particles D. Particles were present.

(Synthesis of strontium titanate particles E)
Strontium titanate particles E were obtained in the same manner as the strontium titanate particles A except that sodium silicate was added and heat-treated at 95 ° C. so that the molar ratio of Si to Ti was 9.

When the strontium titanate particles E were analyzed using SEM-EDS X-ray analysis, sodium silicate particles were present on the surface of the strontium titanate particles E, and sodium silicate was also inside the strontium titanate particles E. Particles were present.

(Manufacturing of toner 1)
Using a Henschel mixer, non-linear polyester A (42 parts by mass), linear polyester B (45 parts by mass), hybrid resin C (13 parts by mass), carbon black (10 parts by mass), carnauba wax WA-03 (Manufactured by Toa Kasei) (3 parts by mass) was stirred and mixed. Next, after kneading at 125 to 130 ° C. for 40 minutes using a roll mill kneader, the mixture was cooled to 25 ° C. and pulverized and classified using a jet mill to obtain parent particles. The base particles had a volume average particle size of 7.0 μm, and the content of particles having a particle size of 5.0 μm or less was 35% by number.

Using a Henschel mixer, maternal particles (100 parts by mass), silica particles HDK-2000 (manufactured by Clariant) (1.0 parts by mass), and strontium titanate particles A (0.7 parts by mass) were mixed at a frequency of 80 Hz for 10 minutes. After mixing, particles having a particle size of 35 μm or more were removed using a sieve to obtain Toner 1.

FIG. 2 shows an SEM image of the toner 1.

(Manufacturing of toner 2)
Toner 2 was obtained in the same manner as in Example 1 except that the strontium titanate particles A were changed to the strontium titanate particles B.

(Manufacturing of toner 3)
Toner 3 was obtained in the same manner as in Example 1 except that the strontium titanate particles A were changed to the strontium titanate particles C.

(Manufacturing of toner 4)
Toner 4 was obtained in the same manner as in Example 1 except that the strontium titanate particles A were changed to the strontium titanate particles D.

(Manufacturing of toner 5)
Toner 5 was obtained in the same manner as in Example 1 except that the strontium titanate particles A were changed to the strontium titanate particles E.

Table 1 shows the characteristics of the toner.

（キャリア１の製造）
ホモミキサーを用いて、固形分濃度４０質量％のシリコーン樹脂溶液（２１００質量部）、アミノシラン（３０質量部）、トルエン（６１００部）を１０分間分散させ、被覆層用塗布液１を得た。

(Manufacturing of carrier 1)
Using a homomixer, a silicone resin solution (2100 parts by mass), aminosilane (30 parts by mass), and toluene (6100 parts by mass) having a solid content concentration of 40% by mass were dispersed for 10 minutes to obtain a coating solution 1 for a coating layer.

Using a Spiracoater (manufactured by Okada Seiko Co., Ltd.), the surface of CuZn-based ferrite particles (hereinafter referred to as core material particles 1) having a volume average particle size of 55 μm and a bulk density of 2.58 g / cm ^{3 is coated in an atmosphere of 60 ° C.} The coating layer coating solution 1 was applied at a rate of 30 g / min so that the layer thickness was 0.50 μm, and then dried. Next, it was fired at 230 ° C. for 1 hour using an electric furnace, cooled, and then crushed using a sieve having a mesh size of 100 μm to obtain a carrier 1.

(Manufacturing of carrier 2)
The carrier 2 is provided in the same manner as the carrier 1 except that the core material particles 1 are changed to CuZn-based ferrite particles (hereinafter referred to as core material particles 2) having a volume average particle diameter of 50 μm and a bulk density of 2.61 g / cm ^3. Obtained.

(Manufacturing of carrier 3)
The carrier 3 was used in the same manner as the carrier 1 except that the core material particles 1 were changed to CuZn-based ferrite particles (hereinafter referred to as core material particles 3) having a volume average particle size of 66 μm and a bulk density of 2.55 g / cm ^3. Obtained.

(Manufacturing of carrier 4)
The carrier 4 was used in the same manner as the carrier 1 except that the core material particles 1 were changed to CuZn-based ferrite particles (hereinafter referred to as core material particles 4) having a volume average particle diameter of 56 μm and a bulk density of 2.30 g / cm ^3. Obtained.

(Manufacturing of carrier 5)
The carrier 5 was used in the same manner as the carrier 1 except that the core material particles 1 were changed to CuZn-based ferrite particles (hereinafter referred to as core material particles 5) having a volume average particle diameter of 53 μm and a bulk density of 2.65 g / cm ^3. Obtained.

(Manufacturing of carrier 6)
A coating liquid 2 for a coating layer was obtained in the same manner as the coating liquid 1 for a coating layer except that barium sulfate particles (1000 parts by mass) having an average particle size of 0.60 μm were added.

A carrier 6 was obtained in the same manner as the carrier 1 except that the coating liquid 1 for the coating layer was changed to the coating liquid 2 for the coating layer.

(Manufacturing of carrier 7)
A coating liquid 3 for a coating layer was obtained in the same manner as the coating liquid 1 for a coating layer except that magnesium oxide particles (1000 parts by mass) having an average particle size of 0.55 μm were added.

A carrier 7 was obtained in the same manner as the carrier 1 except that the coating liquid 1 for the coating layer was changed to the coating liquid 3 for the coating layer.

(Manufacturing of carrier 8)
A coating liquid 4 for a coating layer was obtained in the same manner as the coating liquid 1 for a coating layer except that hydrotalcite particles (1000 parts by mass) having an average particle size of 0.58 μm were added.

A carrier 8 was obtained in the same manner as the carrier 1 except that the coating liquid 1 for the coating layer was changed to the coating liquid 4 for the coating layer.

(Manufacturing of carrier 9)
The carrier 9 was used in the same manner as the carrier 1 except that the core material particles 1 were changed to CuZn-based ferrite particles (hereinafter referred to as core material particles 6) having a volume average particle diameter of 42 μm and a bulk density of 2.60 g / cm ^3. Obtained.

(Manufacturing of carrier 10)
The carrier 10 was used in the same manner as the carrier 1 except that the core material particles 1 were changed to CuZn-based ferrite particles (hereinafter referred to as core material particles 7) having a volume average particle diameter of 72 μm and a bulk density of 2.50 g / cm ^3. Obtained.

(Manufacturing of carrier 11)
The carrier 11 was used in the same manner as the carrier 1 except that the core material particles 1 were changed to CuZn-based ferrite particles (hereinafter referred to as core material particles 8) having a volume average particle diameter of 61 μm and a bulk density of 2.22 g / cm ^3. Obtained.

(Manufacturing of carrier 12)
The carrier 12 was used in the same manner as the carrier 1 except that the core material particles 1 were changed to CuZn-based ferrite particles (hereinafter referred to as core material particles 9) having a volume average particle diameter of 50 μm and a bulk density of 2.70 g / cm ^3. Obtained.

Table 2 shows the characteristics of the carriers.

（実施例１〜１０、比較例１〜６）
ミキサーを用いて、トナー７部と、キャリア９３部を３分間攪拌して、現像剤を得た（表３参照）。

(Examples 1 to 10, Comparative Examples 1 to 6)
Using a mixer, 7 parts of the toner and 93 parts of the carrier were stirred for 3 minutes to obtain a developer (see Table 3).

Next, a developer is set on the digital full-color multifunction device Pro C9100 (manufactured by Ricoh) to form an image, and toner scattering, background fog, image density (ID), edge carrier adhesion, solid carrier adhesion, ghost image, and photoconductor are formed. Abrasion was evaluated.

(Toner scattering)
After running 1 million sheets, the toner accumulated in the lower part of the developer carrier was recovered by suction, and the mass of the recovered toner was measured to evaluate the toner scattering.

The criteria for determining toner scattering are shown below.

When the mass of toner is 0 mg or more and less than 50 mg: ◎ (very good)
When the mass of toner is 50 mg or more and less than 100 mg: ○ (good)
When the mass of toner is 100 mg or more and less than 250 mg: Δ (usable)
When the mass of toner is 250 mg or more: × (defective)
(Skin cover)
After running 1 million sheets, the power was turned off during development of a solid white image, development was interrupted, the toner on the photoconductor was transferred to tape, and a 938 spectrodensitometer (manufactured by X-Rite) was used. The difference (ΔID) from the image density of the transfer tape was measured to evaluate the background fog.

The criteria for determining skin fog are shown below.

When ΔID is 0 or more and less than 0.005: ◎ (very good)
When ΔID is 0.005 or more and less than 0.01: ○ (good)
When ΔID is 0.01 or more and less than 0.02: Δ (available)
When ΔID is 0.02 or more: × (defective)
(ID)
After running 1 million sheets, a solid white image and a solid black image are printed on 3 sheets each of A3 paper MyPaper (manufactured by Ricoh), and using a 938 spectrodensitometer (manufactured by X-Rite), status A mode, d50. The ID of the solid black image was measured with light.

The ID judgment criteria are shown below.

When the ID of the solid black image is 1.5 or more: ◎ (very good)
When the ID of the solid black image is 1.4 or more and less than 1.5: ○ (good)
When the ID of the solid black image is 1.2 or more and less than 1.4: △ (Available)
When the ID of the solid black image is less than 1.2: × (defective)
(Adhesion of edge carrier)
After running 1 million sheets, a digital full-color multifunction device was placed in an environmental evaluation room in a low-temperature, low-humidity environment at 10 ° C. and 15% RH, and left for one day. Next, with 170 μm × 170 μm as one cell, an A3 size image in which solid image parts and blank paper parts are arranged alternately vertically and horizontally is output under the conditions of charging potential of -630V and development bias of -500V (DC). The number of white spots in the image at the boundary between the squares and one square was counted, and the edge carrier adhesion was evaluated.

The criteria for determining the adhesion of edge carriers are shown below.

When the number of white spots in the image is 0: ◎ (very good)
When the number of white spots in the image is 1-3: ○ (good)
When the number of white spots in the image is 4 to 10: △ (Available)
When the number of white spots in the image is 11 or more: × (defective)
(Attachment of solid carrier)
After running 1 million sheets, under the conditions of charging potential -600V, exposure potential -100V of the solid image part, and development bias 500V (DC), the power was turned off during development of the solid image to interrupt the development, and the image was exposed. The number of carriers attached to the region of 10 mm × 100 mm on the body was counted, and the solid carrier adhesion was evaluated.

The criteria for determining solid carrier adhesion are shown below.

When the number of carriers attached is 0: ◎ (very good)
When the number of carriers attached is 1 to 3: ○ (good)
When the number of carriers attached is 4 to 10: △ (usable)
When the number of carriers attached is 11 or more: × (defective)
(Ghost image)
After running 1 million sheets, print an A4 size vertical band chart (see Fig. 3) with an image area ratio of 8%, and use a 938 spectrodensitometer (manufactured by X-Rite) for one round of the sleeve and one round later. The density difference was measured at three points, the center, the rear, and the front, and the average density difference ΔID at the three points was obtained to evaluate the ghost image.

The criteria for determining the ghost image are shown below.

When ΔID is 0.01 or less: ◎ (very good)
When ΔID is more than 0.01 and 0.03 or less: ○ (good)
When ΔID is more than 0.03 and 0.06 or less: Δ (available)
When ΔID exceeds 0.06: × (defective)
(Photoreceptor wear)
After running 1 million sheets, 3D data was acquired from 3D image concatenation using a microscope VHX-6000 (manufactured by KEYENCE). Next, the unevenness of the entire surface of the photoconductor before and after running was measured, the thickness of the photoconductor that disappeared was determined, and the wear of the photoconductor was evaluated.

The criteria for determining the wear of the photoconductor are shown below.

When the thickness of the disappeared photoconductor is 2 μm or less: ◎ (very good)
When the thickness of the disappeared photoconductor exceeds 2 μm and is 3 μm or less: ○ (good)
When the thickness of the disappeared photoconductor exceeds 3 μm: × (defective)
Table 3 shows the evaluation results of the developer.

表３から、実施例１〜１０の現像剤は、長期間印刷しても、画像濃度が高く、キャリア付着、トナー飛散、地肌かぶり及びゴースト画像の発生並びに感光体の摩耗を抑制できることがわかる。

From Table 3, it can be seen that the developing agents of Examples 1 to 10 have a high image density even when printed for a long period of time, and can suppress carrier adhesion, toner scattering, background fog, generation of ghost images, and wear of the photoconductor.

On the other hand, since the developer of Comparative Example 1 has a carrier 9 having a volume average particle diameter of 43 μm, edge carrier adhesion occurs when printing for a long period of time.

Since the developer of Comparative Example 2 has a carrier 10 having a volume average particle diameter of 73 μm, when printed for a long period of time, the image density decreases, and solid carrier adhesion and ghost images occur.

Since the developer of Comparative Example 3 has a carrier 11 having a bulk density of 2.06 g / cm ³ , edge carrier adhesion occurs when printing for a long period of time.

Since the developer of Comparative Example 4 has a carrier 12 having a bulk density of 2.53 g / cm ³ , the image density decreases and solid carrier adhesion occurs when printing for a long period of time.

The developer of Comparative Example 5 has a toner 4 containing strontium titanate particles D having sodium titanate particles having a diameter equivalent to a number average circle of 17.2 μm on the surface. Occurs.

Since the developer of Comparative Example 6 has a toner 5 containing strontium titanate particles E having sodium titanate particles having a diameter equivalent to a number average circle of 4.3 μm on the surface, the photoconductor wears when printed for a long period of time. ..

10 Process cartridge 11 Photoreceptor 12 Charging device 13 Developing device 14 Cleaning device

Japanese Unexamined Patent Publication No. 2019-28235 Japanese Unexamined Patent Publication No. 58-108548 Special Fair 1-19584 Gazette Special Fair 3-628 Gazette Japanese Unexamined Patent Publication No. 6-20231

Claims (10)

Has toner and carrier,
The toner contains strontium titanate particles having Si-containing particles on the surface, and the toner contains strontium titanate particles.
The Si-containing particles have a diameter equivalent to a number average circle of 5 nm or more and 15 nm or less.
In the carrier, the surface of the core material particles is coated with a coating layer containing a resin, the volume average particle size is 45 μm or more and 70 μm or less, and the bulk density is 2.10 g / cm ³ or more and 2.50 g / cm ³ or less. Is a developer. The developer according to claim 1, wherein the coating layer further contains inorganic particles. The developer according to claim 2, wherein the inorganic particles include a material selected from the group consisting of barium sulfate, zinc oxide, magnesium oxide, magnesium hydroxide and hydrotalcite. The developer according to any one of claims 1 to 3, wherein the strontium titanate particles have a diameter equivalent to a number average circle of primary particles of 20 nm or more and 40 nm or less, and a BET specific surface area of 50 m ^{2 / g or more.} The developer according to any one of claims 1 to 4, wherein the strontium titanate particles have a molar ratio of Si to Ti of 1.0 or more and 10.0 or less. The toner further contains ester wax and
The developer according to any one of claims 1 to 5, wherein the circle-equivalent diameter of the ester wax in the cross section of the toner is 0.1 μm or more and 0.5 μm or less. The toner further comprises polyester and
In the FT-IR spectrum obtained by measuring the toner by the ATR method, where W is the maximum height of the peak derived from the ester wax and R is the maximum height of the peak derived from the polyester, the formula 0 .05 ≤ W / R ≤ 0.14
The developer according to claim 6, which satisfies the above conditions. A developing apparatus for developing an electrostatic latent image formed on a photoconductor using the developer according to any one of claims 1 to 7. A process cartridge having the developing apparatus according to claim 8. An image forming apparatus having the developing apparatus according to claim 8.

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