JP6379917B2 - Electrostatic charge image developer, image forming method and image forming apparatus - Google Patents

Description

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

  A method of visualizing image information through an electrostatic latent image, such as electrophotography, is currently widely used in various fields. In the electrophotographic method, the electrostatic latent image on the surface of the photosensitive member (image holding member) is developed with a developer containing toner through a charging step, an exposure step, and the like, and the electrostatic process is performed through a transfer step, a fixing step and the like. The latent image is visualized.

As conventional toners, for example, those described in Patent Documents 1 and 2 are known.
In Patent Document 1, in an electrostatic latent image developing toner having at least particles containing a binder resin, a colorant and a release agent and an external additive, the external additive is heated at 25 to 250 ° C. An electrostatic latent image developing toner having a mass reduction rate of 0.05% by mass or more and less than 4.50% by mass is described.
In Patent Document 2, in an electrophotographic toner composition comprising a toner particle containing a binder and a colorant and an additive, the additive is treated with a coupling agent to have a specific surface area of 60 to 100 m. There is described an electrophotographic toner composition comprising crystalline titanium oxide fine particles having ² / g and Karl Fischer water content of 5% by weight or less.

JP 2007-79205 A Japanese Patent Laid-Open No. 7-230179

  SUMMARY OF THE INVENTION An object of the present invention is to provide an electrostatic charge image developer capable of suppressing carrier adhesion to an image carrier (photoreceptor) due to a decrease in carrier resistance after continuous image formation, and developing machine contamination. is there.

The above-described problems of the present invention have been solved by the means described in <1>, <3> or <4> below. It is described below together with <2> which is a preferred embodiment.
<1> Toner base particles containing at least a binder resin and an external additive having a crystallite diameter of 12.0 nm to 16.0 nm and a weight loss in a thermogravimetric analysis of 100 ° C. to 500 ° C. Characterized in that it contains a toner containing metatitanic acid particles of 0.5% by mass or more and 2.5% by mass or less, a magnetic core material, and a carrier having a coating layer covering the magnetic core material. An electrostatic charge image developer,
<2> The electrostatic charge image developer according to <1>, wherein the content of the metatitanic acid particles is 0.3% by mass or more and 2% by mass or less based on the total mass of the toner.
<3> A charging step for charging at least the image carrier, an exposure step for forming an electrostatic latent image on the surface of the image carrier, and an electrostatic image developer for forming the electrostatic latent image formed on the surface of the image carrier. A developing step for forming a toner image by developing the toner image, a transfer step for transferring the toner image formed on the surface of the image carrier to the surface of the transfer target, and a fixing step for fixing the toner image, An image forming method, wherein the developer is the electrostatic charge image developer according to <1> or <2>;
<4> An image carrier, a charging unit that charges the image carrier, an exposure unit that exposes the charged image carrier to form an electrostatic latent image on the image carrier, and a developer. A developing unit that develops an electrostatic latent image to form a toner image; a transfer unit that transfers the toner image from the image holding member to a transfer target; and a fixing unit that fixes the toner image; An image forming apparatus, wherein the developer is the electrostatic charge image developer according to <1> or <2>.

According to the invention described in <1> above, the external additive of the toner has a crystallite diameter of 12.0 nm to 16.0 nm and a weight loss of 0 ° C. to 500 ° C. in a thermogravimetric analysis is 0. Compared to the case of not containing metatitanic acid particles of 5% by mass or more and 2.5% by mass or less, carrier adhesion to an image carrier (photoreceptor) and development accompanying a decrease in carrier resistance after continuous image formation, and development It is possible to provide an electrostatic charge image developer capable of suppressing machine contamination.
According to the invention described in the above <2>, the carrier resistance after continuous image formation is compared with the case where the content of the metatitanic acid particles is not 0.3% by mass or more and 2% by mass or less with respect to the total mass of the toner. It is possible to provide an electrostatic charge image developer that can further suppress the deterioration of the toner.
According to the invention described in <3> above, the external additive of the toner has a crystallite diameter of 12.0 nm to 16.0 nm and a weight loss in thermogravimetric analysis of 100 ° C. to 500 ° C. is 0. Compared to the case of not containing metatitanic acid particles of 5% by mass or more and 2.5% by mass or less, carrier adhesion to an image carrier (photoreceptor) and development accompanying a decrease in carrier resistance after continuous image formation, and development An image forming method capable of suppressing machine contamination can be provided.
According to the invention described in <4> above, the external additive of the toner has a crystallite diameter of 12.0 nm to 16.0 nm and a weight loss of 0 ° C. to 500 ° C. in a thermogravimetric analysis of 0. Compared to the case of not containing metatitanic acid particles of 5% by mass or more and 2.5% by mass or less, carrier adhesion to an image carrier (photoreceptor) and development accompanying a decrease in carrier resistance after continuous image formation, and development An image forming apparatus capable of suppressing machine contamination can be provided.

Hereinafter, this embodiment will be described in detail. In the present embodiment, the description “A to B” represents not only a range between A and B but also a range including A and B at both ends thereof.
In the present embodiment, “mass%” and “weight%” are synonymous, and “mass part” and “weight part” are synonymous.

(Electrostatic image developer)
The electrostatic charge image developer (hereinafter, also simply referred to as “developer”) of this embodiment has a crystallite diameter of 12.0 nm or more and 16.5 as a toner base particle containing at least a binder resin and an external additive. A toner containing metatitanic acid particles having a weight loss of 0.5% by mass or more and 2.5% by mass or less in a thermogravimetric analysis (TGA) at 0 ° C. or less and 100 ° C. or more and 500 ° C. or less, a magnetic core, And a carrier having a coating layer that coats the magnetic core material.

As a result of detailed studies by the present inventors, as a toner external additive, the weight loss in a thermogravimetric analysis with a crystallite diameter of 12.0 nm to 16.0 nm and 100 ° C. to 500 ° C. is 0.5. It has been found that an electrostatic charge image developer capable of suppressing a decrease in carrier resistance after continuous image formation can be obtained by containing metatitanic acid particles in an amount of not less than 2.5% by mass and not more than 2.5% by mass. Although the mechanism by which the detailed effect appears is unknown, when creating images for a long time using a two-component developer, metatitanic acid released from the toner adheres to the carrier surface, and the crystallite size of the metatitanic acid particles is reduced. The surface roughness is reduced by setting it to 12.0 nm or more and 16.0 nm or less, and wear and peeling of the coating layer due to physical stress such as contact between carriers and contact between the carrier and the metatitanic acid particles when the developing machine is stirred. The present inventors presume that it is possible to prevent the decrease in carrier resistance, and the weight loss of TGA of metatitanic acid particles of 100 ° C. or more and 500 ° C. or less is 0.5% by mass or more and 2% or less. The present inventors presume that by controlling the amount to 5% by mass or less, the amount of adhesion to the carrier and the decrease in carrier resistance during the adhesion are suppressed.
In addition, the electrostatic charge image developer according to the exemplary embodiment can suppress a decrease in carrier resistance, and also suppress the occurrence of a phenomenon (hereinafter, also referred to as “toner cloud”) in which the toner scatters and the inside of the developing machine becomes dirty. Furthermore, the occurrence of a bead-carry-out phenomenon (hereinafter also referred to as “BCO”) in which not only toner but also a carrier is developed can be suppressed.

〔toner〕
The electrostatic charge image developer according to the exemplary embodiment includes toner base particles containing at least a binder resin and, as an external additive, a crystallite diameter of 12.0 nm to 16.0 nm, and 100 ° C. to 500 ° C. A toner containing metatitanic acid particles whose weight loss in thermogravimetric analysis is 0.5% by mass or more and 2.5% by mass or less is contained.

<Metatitanic acid particles>
The electrostatic charge image developing toner used in the exemplary embodiment has a crystallite diameter of 12.0 nm to 16.0 nm as an external additive, and a weight loss in a thermogravimetric analysis of 100 ° C. to 500 ° C. is 0.00. It contains metatitanic acid particles in an amount of 5 to 2.5% by mass.
The metatitanic acid particles are particles containing TiO (OH) ₂ as a main component, and the content of TiO (OH) ₂ is preferably 50% by mass with respect to the total mass of the particles, and 80% by mass. More preferably, it is more preferably 90% by mass.
Examples of other components in the metatitanic acid particles include TiO ₂ and a compound derived from a surface treatment agent described later.
In this embodiment, what was synthesize | combined by the sulfuric acid method as metatitanic acid may be used.
As the sulfuric acid method, titanium ore, ilmenite ore (FeTiO ₃ ), titanium oxide (TiO ₂ ), etc. are heated and dissolved in concentrated sulfuric acid to prepare a solution of titanium sulfate (Ti (SO ₄ ) ₂ ). A preferred method is to obtain particulate metatitanic acid by heat hydrolysis.

The crystallite diameter of the metatitanic acid particles is 12.0 to 16.0 nm, preferably 12.5 to 15.5 nm, and more preferably 13.0 to 15.0 nm. Within the above range, carrier resistance is excellent, toner cloud generation is further suppressed, and BCO generation is further suppressed.
When the crystallite diameter of metatitanic acid is smaller than 12.0 nm, the surface roughness of metatitanic acid is increased, coat abrasion and peeling of the carrier progress, and carrier resistance may be lowered. When the crystallite diameter is larger than 16.0 nm, the resistance of metatitanic acid may decrease and the carrier resistance may decrease.
The “crystallite” in this embodiment means individual single crystals constituting a polycrystal or a single crystal observed in an amorphous state.

The method for measuring the crystallite size of the metatitanic acid particles in the present embodiment is as follows.
The peak of the (101) plane of the metatitanic acid particles is measured by powder X-ray diffraction method, and the average value L of the crystallite diameter can be obtained from the following formula (1) of Scherrer. The crystallite diameter of
L = Kλ / (βcos θ) (1)
Here, K is a constant, λ is a wavelength, β is a half width, and θ is an incident angle.

The weight loss in the thermogravimetric analysis (TGA) of the metatitanic acid particles of 100 ° C. or more and 500 ° C. or less is 0.5% by mass or more and 2.5% by mass or less, and 0.7 to 2.2% by mass. Is preferable, and it is more preferable that it is 1.0-2.0 mass%. Within the above range, the carrier resistance after continuous image formation is excellent, the generation of toner cloud is further suppressed, and the generation of BCO is further suppressed.
When the TGA weight loss of 100 ° C. or more and 500 ° C. or less of the metatitanic acid particles is smaller than 0.5% by mass, the electrostatic adhesion is strong and the liberation amount of the metatitanic acid particles from the toner is small. Wear and peeling may progress. In addition, when the TGA weight loss of 100 ° C. or more and 500 ° C. or less of the metatitanic acid particles is larger than 2.5% by mass, the resistance of the metatitanic acid particles may decrease and the carrier resistance may decrease. Further, since the amount of liberated metatitanic acid particles from the toner is large, carrier resistance may be reduced.
The “weight loss in thermogravimetric analysis (TGA) of 100 ° C. or more and 500 ° C. or less” means a mass measured by a temperature change from 100 ° C. to 500 ° C. by performing thermogravimetric analysis (TGA) according to the following method. The weight loss.
The measuring method of the weight loss in the thermogravimetric analysis (TGA) of the metatitanic acid particles in the present embodiment at 100 ° C. or more and 500 ° C. or less is as follows.
100 in a thermogravimetric analysis (TGA) measuring device (device name: DTG-60AH, manufacturer: Shimadzu Corporation) when the temperature is increased at a temperature increase rate of 30 ° C./30° C./min in a nitrogen gas atmosphere. The amount of mass change from 0 to 500 ° C. was defined as the weight loss in thermogravimetric analysis (TGA).

The metatitanic acid particles are preferably particles whose surfaces are hydrophobized.
The method for hydrophobizing metatitanic acid particles is not particularly limited, and the treatment can be performed using a known hydrophobizing agent.
Although there is no restriction | limiting in particular as a hydrophobization processing agent, For example, coupling agents, such as a silane coupling agent, a titanate coupling agent, or an aluminum coupling agent, or silicone oil etc. are mentioned. The hydrophobizing agent may be used alone or in combination of two or more.

As the silane coupling agent, for example, any of chlorosilane, alkoxysilane, silazane, and a special silylating agent can be used. Specifically, hexamethyldisilazane, methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, phenyltrichlorosilane, diphenyldichlorosilane, tetramethoxysilane, methyltrimethoxysilane, isobutyltrimethoxysilane, octyltrimethoxysilane, dimethyldimethoxy Silane, phenyltrimethoxysilane, diphenyldimethoxysilane, tetraethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, diphenyldiethoxysilane, isobutyltriethoxysilane, octyltriethoxysilane, decyltrimethoxysilane, Hexamethyldisilazane, N, O- (bistrimethylsilyl) acetamide, N, N- (trimethylsilyl) urea tert-butyldimethylchlorosilane, vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyl Examples include trimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-mercaptopropyltrimethoxysilane, and γ-chloropropyltrimethoxysilane.
Examples of other coupling agents include titanate coupling agents and aluminate coupling agents.
In order to perform the hydrophobic treatment using the coupling agent, the coupling agent may be added to the slurry of the metatitanic acid particles.
Examples of the silicone oil used for the hydrophobizing treatment include dimethyl silicone oil, fluorine-modified silicone oil, amino-modified silicone oil, and the like.
Examples of the method for hydrophobizing using silicone oil include a general spray drying method, but are not particularly limited as long as the surface treatment can be performed.
In the present embodiment, metatitanic acid particles hydrophobized with alkoxysilane are preferred from the viewpoint of uniform treatment (high degree of hydrophobization).
Among these, as the hydrophobizing agent, hexamethyldisilazane, isobutyltrialkoxysilane, octyltrialkoxysilane, and silicone oil are preferable.
As a usage-amount of a hydrophobization processing agent, it is preferable that it is 5-80 mass parts with respect to 100 mass parts of metatitanic acid particles, and it is more preferable that it is 10-50 mass parts.

The number average particle diameter of the metatitanic acid particles is preferably 20 to 60 nm, more preferably 20 to 50 nm, and still more preferably 20 to 40 nm.
In the present embodiment, the number average particle diameter of the metatitanic acid particles refers to a particle diameter measured by the following method.
The externally added toner is observed using a scanning electron microscope (SEM), and the particle diameter of the external additive adhering to the toner surface is measured. The measurement conditions are a magnification of 30,000, a visual field: two visual fields, and a measurement number of 100. The particle diameter refers to the diameter of a circle having an area equal to the observed projected area of the external additive.
Based on the measurement results, the particle diameter is plotted as the X axis and the number of particles (external additives) at each particle diameter is plotted as the Y axis, and the particle diameter corresponding to the peak is defined as the number average particle diameter. When two or more peaks are present, the particle diameter corresponding to each peak is defined as the number average particle diameter.

  The content of metatitanic acid particles contained in the toner as an external additive is preferably 0.1 to 10 parts by mass, and preferably 0.2 to 5 parts by mass with respect to 100 parts by mass of the toner base particles. Is more preferably 0.3 to 2 parts by mass, and particularly preferably 0.5 to 1.5 parts by mass. Within the above range, the carrier resistance after continuous image formation is excellent, the generation of toner cloud is further suppressed, and the generation of BCO is further suppressed.

Although there is no restriction | limiting in particular as a manufacturing method of a metatitanic acid particle, It is preferable to manufacture using a wet precipitation method, and manufacturing with the following manufacturing method is more preferable.
It is preferable to perform dispersion adjustment and water washing for hydrolysis and nucleation in the course of production using a wet precipitation method of TiO (OH) ₂ . Moreover, at the time of the said water washing, it is preferable to mix and stir with 10 ppm polycarboxylic acid and water with respect to solid content after water washing.
After drying the obtained TiO (OH) ₂ , it is preferable to perform two-stage baking. Next, it is preferable to perform surface treatment with a hydrophobizing agent to produce metatitanic acid particles.
The two-stage firing is preferably performed at 600 ° C to 850 ° C for 0.1 to 10 minutes, more preferably at 650 ° C to 850 ° C for 0.5 to 5 minutes, The second stage baking is preferably performed at 400 ° C. to 600 ° C. for 20 to 240 minutes, and more preferably at 450 ° C. to 550 ° C. for 30 to 200 minutes.

<Toner base particles>
The electrostatic image developing toner used in this embodiment contains toner mother particles.
The toner base particles used in the exemplary embodiment contain at least a binder resin and, if necessary, a colorant and a release agent.

-Binder resin-
The binder resin contained in the toner base particles is not particularly limited. For example, styrenes such as styrene, parachlorostyrene, and α-methylstyrene; methyl acrylate, ethyl acrylate, n-propyl acrylate, acrylic Esters having vinyl groups such as n-butyl acid, lauryl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate; acrylonitrile, methacrylate Vinyl nitriles such as ronitrile; Vinyl ethers such as vinyl methyl ether and vinyl isobutyl ether; Vinyl ketones such as vinyl methyl ketone, vinyl ethyl ketone and vinyl isopropenyl ketone; Polyethylene such as ethylene, propylene and butadiene Homopolymer consisting of a monomer such as olefins include, or copolymers obtained by combining two or more kinds, even mixtures thereof. In addition, epoxy resins, polyester resins, polyurethane resins, polyamide resins, cellulose resins, polyether resins, etc., non-vinyl condensation resins, or a mixture of these with the vinyl resin, or vinyl monomers in the presence of these resins Examples thereof include a graft polymer obtained by polymerization.

Styrene resin, (meth) acrylic resin, and styrene- (meth) acrylic copolymer resin are obtained by known methods, for example, by combining styrene monomers and (meth) acrylic acid monomers alone or in appropriate combination. It is done. “(Meth) acryl” is an expression including both “acryl” and “methacryl”.
When using a styrene resin, a (meth) acrylic resin or a copolymer resin thereof as a binder resin, the weight average molecular weight Mw is 20,000 or more and 100,000 or less, and the number average molecular weight Mn is 2,000 or more and 30,000 or less. It is preferable to use the thing of the range.

Among these, as the binder resin, a polyester resin is preferable.
The polyester resin used in this embodiment is synthesized from a polyol component and a polycarboxylic acid component by polycondensation. In addition, in this embodiment, a commercial item may be used as said polyester resin, and what was synthesize | combined suitably may be used.
Examples of the polyvalent carboxylic acid component include oxalic acid, succinic acid, glutaric acid, adipic acid, peric acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid, 1,12 -Aliphatic dicarboxylic acids such as dodecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,18-octadecanedicarboxylic acid, phthalic acid, isophthalic acid, terephthalic acid, naphthalene-2,6-dicarboxylic acid, malonic acid, mesaconic acid And aromatic dicarboxylic acids such as dibasic acids. Furthermore, these anhydrides and these lower alkyl esters are also exemplified, but not limited thereto.
Examples of the trivalent or higher carboxylic acid include 1,2,4-benzenetricarboxylic acid, 1,2,5-benzenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, and the like, anhydrides thereof, and the like. And lower alkyl esters. These may be used individually by 1 type and may use 2 or more types together.
Furthermore, it is more preferable to contain a dicarboxylic acid component having an ethylenically unsaturated double bond in addition to the above-mentioned aliphatic dicarboxylic acid and aromatic dicarboxylic acid. A dicarboxylic acid having an ethylenically unsaturated double bond is preferably used to prevent hot offset at the time of fixing in that it can be radically crosslinked through the ethylenically unsaturated double bond. Examples of such dicarboxylic acids include, but are not limited to, maleic acid, fumaric acid, 3-hexenedioic acid, and 3-octenedioic acid. In addition, these lower esters, acid anhydrides and the like are also included. Among these, fumaric acid, maleic acid and the like are mentioned in terms of cost.

Examples of the polyhydric alcohol component include polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene (2.2) -2,2 -Bisphenol A alkylene (carbon number 2 to 4) oxide adduct (average number of added moles 1.5 to 6) such as bis (4-hydroxyphenyl) propane, ethylene glycol, propylene glycol, neopentyl glycol, 1, 4 -Butanediol, 1,3-butanediol, 1,6-hexanediol and the like.
Examples of the trihydric or higher polyhydric alcohol include sorbitol, pentaerythritol, glycerol, trimethylolpropane and the like.
In the amorphous polyester resin (also referred to as “non-crystalline polyester resin”), among the raw material monomers described above, a dihydric or higher secondary alcohol and / or a divalent or higher aromatic carboxylic acid compound is preferable. Examples of the dihydric or higher secondary alcohol include a propylene oxide adduct of bisphenol A, propylene glycol, 1,3-butanediol, and glycerol. In these, the propylene oxide adduct of bisphenol A is preferable.
As the divalent or higher aromatic carboxylic acid compound, terephthalic acid, isophthalic acid, phthalic acid and trimellitic acid are preferable, and terephthalic acid and trimellitic acid are more preferable.

Further, it is preferable to use a crystalline polyester resin as a part of the binder resin in order to impart low-temperature fixability to the toner.
The crystalline polyester resin is preferably composed of an aliphatic dicarboxylic acid and an aliphatic diol, and more preferably a linear dicarboxylic acid or a linear aliphatic diol having 4 to 20 carbon atoms in the main chain portion. The linear type is excellent in the crystallinity of the polyester resin and has an appropriate crystal melting point, and thus is excellent in toner blocking resistance, image storage stability, and low-temperature fixability. Further, when the carbon number is 4 or more, the ester bond concentration is low, the electric resistance is moderate, and the toner charging property is excellent. Further, when it is 20 or less, it is easy to obtain practical materials. The carbon number is more preferably 14 or less.

Examples of the aliphatic dicarboxylic acid suitably used for the synthesis of the crystalline polyester include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelinic acid, sebacic acid, 1,9-nonane. Dicarboxylic acid, 1,10-decanedicarboxylic acid, 1,11-undecanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,13-tridecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,16-hexadecanedicarboxylic acid An acid, 1,18-octadecanedicarboxylic acid or the like, or a lower alkyl ester or an acid anhydride thereof may be mentioned, but not limited thereto. Among these, considering availability, sebacic acid and 1,10-decanedicarboxylic acid are preferable.
Specific examples of the aliphatic diol include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, and 1,7-heptanediol. 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol 1,18-octadecanediol, 1,14-eicosandecanediol and the like, but are not limited thereto. Among these, 1,8-octanediol, 1,9-nonanediol, and 1,10-decanediol are preferable in view of availability.
Examples of the trivalent or higher alcohol include glycerin, trimethylolethane, trimethylolpropane, pentaerythritol and the like. These may be used individually by 1 type and may use 2 or more types together.

Among the polyvalent carboxylic acid components, the content of the aliphatic dicarboxylic acid is preferably 80 mol% or more, and more preferably 90 mol% or more. When the content of the aliphatic dicarboxylic acid is 80 mol% or more, the polyester resin is excellent in crystallinity and has an appropriate melting point, and therefore toner blocking resistance and image storage stability. And it is excellent in low-temperature fixability.
Among the polyhydric alcohol components, the content of the aliphatic diol component is preferably 80 mol% or more, and more preferably 90 mol% or more. When the content of the aliphatic diol component is 80 mol% or more, the polyester resin is excellent in crystallinity and has an appropriate melting point, so that it is excellent in toner blocking resistance, image storage stability, and low-temperature fixability.

In the present embodiment, the melting temperature Tm of the crystalline polyester resin is preferably 50 to 100 ° C, more preferably 50 to 90 ° C, and still more preferably 50 to 80 ° C. The above range is preferable because it is excellent in peelability and low-temperature fixability and further reduces offset.
Here, for the measurement of the melting temperature of the crystalline polyester resin, a differential scanning calorimeter was used, and JIS K-7121 was measured at a temperature rising rate of 10 ° C. per minute from room temperature (20 ° C.) to 180 ° C. : It can obtain | require as a melting peak temperature of the input compensation differential scanning calorimetry shown to 87. In addition, although crystalline polyester resin may show a some melting peak, in this embodiment, let the maximum peak be melting temperature.

On the other hand, the glass transition temperature (Tg) of the amorphous polyester resin is preferably 30 ° C. or higher, more preferably 30 to 100 ° C., and still more preferably 50 to 80 ° C. If it is in the above range, since it is in a glass state in use, toner particles do not aggregate due to heat and pressure received during image formation, and do not adhere and accumulate in the machine, and stable image forming ability over a long period of time. can get.
Here, the glass transition temperature of the non-crystalline polyester resin refers to a value measured by a method (DSC method) defined in ASTM D3418-82.
Moreover, the measurement of the glass transition temperature in this embodiment can be measured by, for example, “DSC-20” (manufactured by Seiko Denshi Kogyo Co., Ltd.) according to the differential scanning calorimetry, and specifically, about 10 mg of a sample. Is heated at a constant rate of temperature increase (10 ° C./min), and the glass transition temperature is obtained from the intersection of the baseline and the endothermic peak tilt line.

The weight average molecular weight of the crystalline polyester resin is preferably 10,000 to 60,000, more preferably 15,000 to 45,000, and still more preferably 20,000 to 30,000. .
The weight average molecular weight of the amorphous polyester resin is preferably 5,000 to 100,000, more preferably 10,000 to 90,000, and 20,000 to 80,000. Is more preferable.
It is preferable that the weight average molecular weights of the crystalline polyester resin and the non-crystalline polyester resin are within the above ranges because both the image strength and the fixability can be achieved. All of the above weight average molecular weights can be obtained by molecular weight measurement by gel permeation chromatography (GPC) method in which tetrahydrofuran (THF) is soluble. The molecular weight of the resin is calculated using a molecular weight calibration curve prepared with a monodisperse polystyrene standard sample by measuring THF soluble material with THF solvent using TSK-GEL (GMH (manufactured by Tosoh Corporation)) etc. Is done.

The acid value of the crystalline polyester resin and the amorphous polyester resin is preferably 1 to 50 mgKOH / g, more preferably 5 to 50 mgKOH / g, and still more preferably 8 to 50 mgKOH / g. . The above range is preferable because it is excellent in fixing characteristics and charging stability.
If necessary, a monovalent acid such as acetic acid or benzoic acid or a monovalent alcohol such as cyclohexanol benzyl alcohol may be used for the purpose of adjusting the acid value or the hydroxyl value.

The production method of the polyester resin is not particularly limited, and can be produced by a general polyester polymerization method in which an acid component and an alcohol component are reacted. Examples thereof include direct polycondensation and transesterification. Depending on the type, it will be manufactured separately. Further, it is preferable to use a polycondensation catalyst such as a metal catalyst or a Bronsted acid catalyst.
The polyester resin may be produced by subjecting the polyhydric alcohol and polyhydric carboxylic acid to a condensation reaction according to a conventional method. For example, the above polyhydric alcohol and polyvalent carboxylic acid, if necessary, a catalyst, and blended in a reaction vessel equipped with a thermometer, a stirrer, a flow-down condenser, Heat at 150 ° C to 250 ° C to continuously remove by-product low-molecular compounds out of the reaction system, stop the reaction when a predetermined acid value or molecular weight is reached, cool, and target reactant Manufactured by obtaining.

The glass transition temperature of the binder resin is preferably in the range of 40 ° C. or higher and 80 ° C. or lower. When the glass transition temperature is in the above range, the minimum fixing temperature is easily maintained.
The content of the binder resin in the toner base particles is not particularly limited, but is preferably 10 to 95% by mass and more preferably 25 to 90% by mass with respect to the total mass of the toner. More preferably, it is 45-85 mass%. Within the above range, the fixing property, the charging property and the like are excellent.

-Colorant-
In the present embodiment, the toner base particles preferably contain a colorant for the purpose of coloring the resulting image.
A known colorant may be used as the colorant, and may be arbitrarily selected from the viewpoints of hue angle, saturation, brightness, weather resistance, OHP permeability, dispersibility in the toner, and the like.
The colorant may be a dye or a pigment, but is preferably a pigment from the viewpoint of light resistance and water resistance. The colorant is not limited to a colored colorant, and may be a white colorant or a colorant exhibiting a metallic color.

For example, in cyan toner, as the colorant, for example, C.I. I. Pigment Blue 1, 2, 3, 4, 5, 6, 7, 10, 11, 12, 13, 13, 15, 15: 1, 15: 2, 15: 3, 15: 4, 15: 6, 16, 17, 17, 23, 60, 65, 73, 83, 180, C.I. I. Vat cyan 1, 3 and 20, etc., bitumen, cobalt blue, alkali blue lake, phthalocyanine blue, metal-free phthalocyanine blue, partially chlorinated phthalocyanine blue, first sky blue, indanthrene blue BC cyan pigment, C.I. I. Cyan dyes such as solvent cyan 79 and 162 are used.
In the magenta toner, as the colorant, for example, C.I. I. Pigment Red 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 11, 12, 13, 14, 15, 16, 17, 18, 19, 21, 21, 22, 23, 30, 31, 32, 37, 38, 39, 40, 41, 48, 49, 70, 51, 52, 53, 54, 55, 57, 58, 60, 63, 64, 68, 81, 83, 87, 88, 89, 90 112, 114, 122, 123, 163, 184, 185, 202, 206, 207, 209, 238, etc., pigment violet 19 magenta pigments, C.I. I. Solvent Red 1, 3, 8, 23, 24, 25, 27, 30, 30, 49, 81, 82, 83, 84, 100, 109, 121, C . I. Disper thread 9, C.I. I. Basic Red 1, 2, 9, 9, 13, 14, 15, 17, 17, 18, 22, 23, 24, 27, 29, 32, 34, the same 35, 36, 37, 38, 39, 40, etc. Magenta dyes, etc., Bengala, Cadmium Red, Lead Tan, Mercury Sulfide, Cadmium, Permanent Red 4R, Resol Red, Pyrazolone Red, Watching Red, Calcium Salt, lake red D, brilliant carmine 6B, eosin lake, rotamin lake B, alizarin lake, brilliant carmine 3B and the like are used.
In the yellow toner, as the colorant, for example, C.I. I. Pigment Yellow 2, 3, 15, 15, 17, 74, 93, 97, 128, 155, 180, 185, 139, and the like are used.
In the black toner, as the colorant, for example, carbon black, activated carbon, titanium black, magnetic powder, Mn-containing nonmagnetic powder, or the like is used. Further, black toner may be obtained by mixing yellow, magenta, cyan, red, green, and blue pigments.
As the colorant, a surface-treated colorant or a pigment dispersant may be used. By selecting the type of the colorant, color toners such as yellow toner, magenta toner, cyan toner, and black toner are prepared.

  The amount of the colorant to be used is not particularly limited, but is preferably 0.1 to 20 parts by mass and more preferably 0.5 to 15 parts by mass with respect to 100 parts by mass of the toner base particles. Moreover, as a coloring agent, these pigments, dyes, etc. can be used individually by 1 type, or 2 or more types can be used together.

  In this embodiment, a color image may be formed as a toner set including a clear toner (transparent toner) that does not contain a colorant. It is suitably used as a clear toner for obtaining a good gloss image by transferring and fixing a color toner image desired to give gloss to the top or the periphery thereof.

-Release agent-
In this embodiment, the toner base particles preferably contain a release agent.
Specific examples of the release agent include, for example, ester wax, polyethylene, polypropylene, or a copolymer of polyethylene and polypropylene, but polyglycerin wax, microcrystalline wax, paraffin wax, carnauba wax, sazol wax, and montanic acid. Ester wax, deoxidized carnauba wax, palmitic acid, stearic acid, montanic acid, brandic acid, eleostearic acid, valinalic acid and other unsaturated fatty acids, stearyl alcohol, aralkyl alcohol, bephenyl alcohol, carnauvyl alcohol, ceryl Saturated alcohols such as alcohol, melyl alcohol, or long-chain alkyl alcohols having a long-chain alkyl group; polyhydric alcohols such as sorbitol; linoleic acid amide Fatty acid amides such as oleic acid amide and lauric acid amide; saturated fatty acid bisamides such as methylene bis stearic acid amide, ethylene bis capric acid amide, ethylene bis lauric acid amide, hexamethylene bis stearic acid amide, ethylene bis oleic acid amide, Unsaturated fatty acid amides such as hexamethylenebisoleic acid amide, N, N′-dioleyl adipic acid amide, N, N′-dioleyl sebacic acid amide; m-xylene bisstearic acid amide, N, N′-di Aromatic bisamides such as stearyl isophthalic acid amide; fatty acid metal salts such as calcium stearate, calcium laurate, zinc stearate, magnesium stearate (generally called metal soap); aliphatic hydrocarbon wax with styrene or Waxes grafted with vinyl monomers such as crylic acid; Fatty acids such as behenic acid monoglycerides and partially esterified products of polyhydric alcohols; Methyl ester compounds having hydroxyl groups obtained by hydrogenation of vegetable oils, etc. Is mentioned.

A mold release agent may be used individually by 1 type, or may use 2 or more types together.
The content of the release agent is preferably 1 to 20 parts by mass and more preferably 3 to 15% by mass with respect to 100 parts by mass of the toner base particles. Within the above range, both good fixing and image quality characteristics can be achieved.

−Charging polarity−
In this embodiment, in order to control the chargeability of the toner base particles and the toner, the surface of the toner base particles may be surface-treated, or a charge control agent may be added to the toner base particles. Is preferably surface-treated.
In particular, when the chargeability is not controlled, the toner base particles are often negatively charged.
As a method for performing the surface treatment so that the toner base particles are positively charged, a method in which polyallylamines, polyaminopropyl biguanide (polyhexanide), polyethyleneimines or the like are attached to or reacted with the surface of the toner base particles is preferably exemplified.
The amino group and biguanide group in the polyallylamines, polyaminopropyl biguanide, and polyethyleneimine may form a salt.
The amino group in the polyallylamines may be a primary amino group, a secondary amino group, and / or a tertiary amino group.
Examples of polyallylamines include polyallylamine, allylamine salt polymer, methyldiallylamine salt polymer, diallyldimethylammonium chloride polymer, polydiallylamine, diallylamine salt polymer, and the like.
In addition, examples of commercially available polyallylamines include PAA series and PAS series manufactured by Nitto Bo Medical Co., Ltd.
Examples of commercially available polyethyleneimines include Nippon Catalyst's Epomin series and Pure Chemicals' polyethyleneimine.

In addition, as a surface treatment method of toner mother particles with polyallylamines, polyaminopropyl biguanides, polyethyleneimines, etc., polyallylamines, polyaminopropyl biguanides, polyethyleneimines, etc. are added to a dispersion containing toner mother particles, and dispersed. A method of adjusting the pH of the liquid to 5 to 7, maintaining the pH and performing a surface treatment is preferable.
The addition amount of polyallylamines, polyaminopropyl biguanides, and polyethyleneimines is preferably 0.01 to 10% by mass, more preferably 0.02 to 2% by mass, based on the total mass of the toner base particles. Preferably, it is 0.05-0.1 mass%. When the amount is in the above range, a toner having a larger positive charge amount and excellent in positive charge stability can be easily obtained.

Examples of the charge control agent that may be added to the toner base particles include the following.
Examples of the positively chargeable charge control agent include nigrosine dyes, quaternary ammonium salts such as tributylbenzylammonium-1-hydroxy-4-naphthosulfonate, tetrabutylammonium tetrafluoroborate, and the like. Onium salts such as phosphonium salts and their lake pigments; triphenylmethane dyes; metal salts of higher fatty acids; diorganotin oxides such as dibutyltin oxide, dioctyltin oxide and dicyclohexyltin oxide; diorganotin borates such as dibutyltin borate Guanidine compounds, imidazole compounds, aminoacrylic resins, polyethyleneimines, and the like.
Examples of negatively chargeable charge control agents include trimethylethane dyes, salicylic acid metal complexes, benzylic acid metal complexes, copper phthalocyanine, perylene, quinacridone, azo pigments, metal complex azo dyes, azochrome complexes. Heavy metal-containing acidic dyes such as calixarene type phenolic condensates, cyclic polysaccharides, resins containing carboxyl groups and / or sulfonyl groups, and the like.
These charge control agents may be used alone or in combination of two or more.
The addition amount of the charge control agent is preferably 0.1 to 5% by mass with respect to the total mass of the toner base particles. When the addition amount is within the above range, good chargeability can be obtained.

-Other external additives-
The electrostatic image developing toner used in the exemplary embodiment may contain an external additive other than the metatitanic acid particles described above.
As the external additive other than the metatitanic acid particles described above, known external additives can be used, and examples thereof include inorganic particles and organic particles. When included, the content is more than that of the metatitanic acid particles described above. It is also preferable that the amount is small.
As other external additives, silica particles and / or titania particles are preferably mentioned.

-Other ingredients-
In this embodiment, the toner base particles may contain other components in addition to the above components. There is no restriction | limiting in particular as another component, A well-known component is mentioned, For example, a lubricant, an abrasive | polishing agent, etc. are mentioned.

-Toner characteristics-
The volume average particle size of the toner used in the exemplary embodiment is preferably 2 to 9 μm, and more preferably 3.0 to 7.0 μm. The effect of this embodiment is more exhibited as it is the said range.
The volume average particle diameter of the toner is preferably measured using Coulter Multisizer-II type (Beckman-Coulter) and the electrolyte is ISOTON-II (Beckman-Coulter).
Specific examples of the measurement method include the following methods.
As a dispersant, 1.0 mg of a measurement sample is added to 2 ml of a 5% aqueous solution of a surfactant, preferably sodium alkylbenzenesulfonate. This is added to 100 ml of the electrolytic solution to prepare an electrolytic solution in which the sample is suspended. The electrolyte in which the sample was suspended was dispersed for 1 minute with an ultrasonic disperser, and the particle size distribution of particles of 1 to 30 μm was measured using the Coulter Multisizer-II type with an aperture diameter of 50 μm. Average distribution and number average distribution are obtained. The number of particles to be measured is 50,000.

Further, it is preferable that the particle size distribution of the toner used in the present embodiment is narrow, and more specifically, 16% diameter (abbreviated as D _16v ) and 84% diameter (D _84v ) as a square root (GSDv), that is, the GSDv represented by the following formula is preferably 1.21 or less, more preferably 1.19 or less, and 1.17 or less. It is particularly preferred.
GSDv = {(D _84v ) / (D _16v )} ^0.5 (1)
(In the formula (1), D _84v and D _16v are particle sizes that are 84% and 16% cumulative when a volume cumulative distribution curve is drawn from the small particle size side with respect to each divided particle size range. )
When the GSDv is in the above range, the generation of particles with an excessively large toner charge amount is suppressed, so that deterioration of fine line reproducibility of multi-order colors is further suppressed.

Furthermore, the toner used in the exemplary embodiment preferably has a shape factor SF1 in the range of 110 to 140, and more preferably in the range of 110 to 130. When the shape is spherical in this range, transfer efficiency and image density are improved, and a high-quality image is formed.
Here, the shape factor SF1 is obtained by the following equation (E).
SF1 = (ML ² / A) × (π / 4) × 100 Formula (E)
In the above formula (E), ML represents the absolute maximum length of the toner, and A represents the projected area of the toner.
The SF1 is quantified mainly by analyzing a microscope image or a scanning electron microscope (SEM) image using an image analyzer, and can be calculated as follows, for example. That is, an optical microscope image of particles scattered on the surface of the slide glass is taken into a Luzex image analyzer through a video camera, the maximum length and projected area of 100 particles are obtained, calculated by the above formula (E), and the average value is It is obtained by seeking.

-Toner production method-
The method for producing the toner used in the exemplary embodiment is not particularly limited, and the toner is produced by a known dry method such as a kneading / pulverizing method or a wet method such as an emulsion aggregation method or a suspension polymerization method. Among these methods, the emulsion aggregation method is preferable.
Hereinafter, a method for producing the toner of this embodiment by the emulsion aggregation method will be described in detail.

  The emulsion aggregation method includes an emulsification step of emulsifying the raw materials constituting the toner to form resin particles (emulsion particles), an aggregation step of forming aggregates of the resin particles, and a fusion step of fusing the aggregates. .

-Emulsification process For example, it is preferable to produce the resin particle dispersion by applying a shearing force to a solution obtained by mixing an aqueous medium and a resin with a disperser. At that time, it is more preferable to form particles by lowering the viscosity of the resin component by heating. A dispersant may be used for stabilizing the dispersed resin particles. Further, if the resin is oily and dissolves in a solvent having a relatively low solubility in water, the resin is dissolved in those solvents and dispersed in an aqueous medium together with a dispersant and a polymer electrolyte, and then heated or The resin particle dispersion may be prepared by evaporating the solvent under reduced pressure.
Examples of the aqueous medium include water such as distilled water and ion-exchanged water; alcohols; and the like, but preferably only water.
Examples of the dispersant used in the emulsification step include water-soluble polymers such as polyvinyl alcohol, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, sodium polyacrylate, and sodium polymethacrylate; sodium dodecylbenzenesulfonate, Anionic surfactants such as sodium octadecyl sulfate, sodium oleate, sodium laurate, potassium stearate, cationic surfactants such as laurylamine acetate, stearylamine acetate, lauryltrimethylammonium chloride, amphoteric such as lauryldimethylamine oxide Ionic surfactant, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene Surfactants such as nonionic surfactants such as alkyl amines; and the like are; tricalcium phosphate, aluminum hydroxide, calcium sulfate, calcium carbonate, inorganic salts such as barium carbonate.

Examples of the disperser used for preparing the emulsion include a homogenizer, a homomixer, a pressure kneader, an extruder, and a media disperser.
As the size of the resin particles, the average particle size (volume average particle size) is preferably in the range of 60 nm to 300 nm, and more preferably in the range of 150 nm to 250 nm. Within the above range, the cohesiveness of the resin particles is sufficient, and the particle size distribution of the toner can be narrowed.

In preparing the release agent dispersion, the release agent is dispersed in water together with a polymer electrolyte such as an ionic surfactant, a polymer acid or a polymer base, and then heated to a temperature equal to or higher than the melting temperature of the release agent. Dispersion treatment is performed using a homogenizer or a pressure discharge type disperser capable of applying a strong shearing force while heating. By undergoing such treatment, a release agent dispersion can be obtained.
By the dispersion treatment, a release agent dispersion liquid containing release agent particles having a volume average particle diameter of preferably 1 μm or less can be obtained. A more preferable volume average particle diameter of the release agent particles is 100 nm or more and 500 nm or less.

Aggregation step In the aggregation step, a resin particle dispersion, a release agent dispersion, a colorant particle dispersion, etc. are mixed to form a mixed solution, and heated at a temperature not higher than the glass transition temperature of the amorphous resin particles. It is preferable to aggregate to form aggregated particles. Aggregated particles are formed by acidifying the pH of the mixed solution under stirring.
The pH is preferably 2 or more and 7 or less, more preferably 2.2 or more and 6 or less, and more preferably 2.4 or more and 5 or less in view of narrowing the particle size distribution of the toner. At this time, it is also effective to use a flocculant.
In the aggregation step, the release agent dispersion may be added and mixed at once with various dispersions such as a resin particle dispersion, or may be added in multiple portions.

As the aggregating agent, a surfactant having a polarity opposite to that of the surfactant used for the dispersant, an inorganic metal salt, and a metal complex having a valence of 2 or more are preferably used. In particular, the use of a metal complex is particularly preferable because the amount of the surfactant used can be reduced and the charging characteristics are further improved.
Examples of the inorganic metal salt include metal salts such as calcium chloride, calcium nitrate, barium chloride, magnesium chloride, zinc chloride, aluminum chloride, and aluminum sulfate, and polyaluminum chloride, polyaluminum hydroxide, and calcium polysulfide. Examples thereof include inorganic metal salt polymers. Among these, an aluminum salt and a polymer thereof are particularly preferable. By increasing the number of additions of the inorganic metal salt, a toner having a smaller GSDv can be obtained.

  Further, a toner having a configuration in which the surface of the core aggregated particles is coated with the resin particles may be prepared by additionally adding resin particles when the aggregated particles have a desired particle size (coating step). In this case, the release agent is less likely to be exposed on the toner surface, which is a preferable configuration from the viewpoint of chargeability and developability. In the case of additional addition, a flocculant may be added or pH adjustment may be performed before additional addition.

-Fusion process In the fusion process, the agglomeration is stopped by raising the pH of the suspension of aggregated particles to a range of 3 to 9 under stirring conditions according to the aggregation process. It is preferable to fuse the aggregated particles by heating at a temperature equal to or higher than the melting temperature. Further, when the aggregated particles are coated with the amorphous resin, it is preferable that the amorphous resin is also fused to cover the core aggregated particles. The heating time may be as long as fusion is performed, and preferably 0.5 hours or more and 10 hours or less.
Cooling is performed after the fusion to obtain fused particles. In the cooling step, crystallization may be promoted by so-called gradual cooling, in which the cooling rate is reduced in the vicinity of the melting temperature of the crystalline resin (in the range of melting temperature ± 10 ° C.).

The fused particles (toner mother particles) obtained by fusing can be made into toner mother particles through a solid-liquid separation process such as filtration, and a washing process and a drying process as necessary.
Further, a step of externally adding an external additive containing metatitanic acid particles to the obtained toner base particles is performed.
The method for externally adding an external additive to the surface of the toner base particles in the external addition step is not particularly limited, and a known method is used. For example, a mechanical method or a chemical method is used. It is done.
Further, if necessary, coarse particles of toner may be removed after external addition using an ultrasonic sieving machine, a vibration sieving machine, a wind sieving machine, or the like.

[Carrier]
The electrostatic charge image developer of this embodiment contains a magnetic core material and a carrier having a coating layer that covers the magnetic core material.

<Magnetic core material>
The carrier used in the present embodiment is a magnetic material dispersed resin particle in which a magnetic material such as magnetite is dispersed in a resin as a magnetic core material of the carrier (hereinafter also simply referred to as “core material”), or a magnetic material particle. However, it is preferable to use magnetic material dispersed resin particles.
Examples of the magnetic material used for the core material include magnetic metals such as iron, steel, nickel, and cobalt, and alloys of these with manganese, chromium, rare earth elements, and the like (for example, nickel-iron alloys, cobalt-iron alloys). , Aluminum-iron alloys, etc.) and magnetic oxides such as ferrite and magnetite can be applied. Among these, iron oxide is preferable. When the magnetic particles are iron oxide particles, it is advantageous in that the characteristics are stable and the toxicity is low.
These magnetic materials may be used alone or in combination of two or more.

  The particle diameter of the magnetic substance to be dispersed is preferably 0.01 to 1 μm, more preferably 0.03 μm to 0.5 μm, and still more preferably 0.05 μm to 0.35 μm. If the particle size of the magnetic powder is in the above range, the saturation magnetization is sufficient, or the viscosity of the composition (monomer mixture) is moderate, a carrier having a uniform particle size can be obtained, and homogeneous magnetic material dispersion Resin particles can be obtained.

  The content of the magnetic substance in the magnetic substance-dispersed resin particles is preferably 30 to 99% by mass, more preferably 45 to 97% by mass, more preferably 60 to 60% by mass with respect to the total mass of the magnetic substance-dispersed resin particles. More preferably, it is 95 mass%. When the content is in the above range, there is little scattering of the carrier (magnetic material dispersed carrier) in which the magnetic material dispersed resin particles are the core material, and the magnetic brush of the magnetic material dispersed carrier is not hard and cracked. Can be suppressed.

  Examples of the resin component in the magnetic material-dispersed resin particles include a cross-linked styrene resin, acrylic resin, styrene-acrylic copolymer resin, and phenol resin.

  In addition to the resin component and the magnetic powder, the magnetic material-dispersed resin particles used in the present embodiment may further contain other components depending on the purpose. Examples of the other components include a charge control agent and fluorine-containing particles.

The volume average particle diameter of the core material in the carrier using magnetic particles as the core material is preferably in the range of 10 to 500 μm, more preferably in the range of 30 to 150 μm, and still more preferably in the range of 30 to 100 μm.
The volume average particle diameter of the core material is a value measured using a laser diffraction / scattering particle size distribution analyzer (LS Particle Size Analyzer: LS13 320, manufactured by BECKMAN COULTER (Beckman Coulter)). For the particle size range (channel) obtained by dividing the obtained particle size distribution, the volume cumulative distribution is subtracted from the small particle size side, and the particle size that becomes 50% cumulative is _defined as the volume average particle size D _50v .

  The method for producing the magnetic material-dispersed resin particles is, for example, a melt-kneading method in which a magnetic powder and a binder resin such as a styrene acrylic resin are melt-kneaded using a Banbury mixer, a kneader, etc. (JP-B-59-24416, JP-B-8-3679, etc.) and a monomer unit of a binder resin and a magnetic powder are dispersed in a solvent to prepare a suspension. Known are suspension polymerization methods for polymerization (JP-A-5-1000049, etc.), spray-drying methods in which a magnetic powder is mixed and dispersed in a resin solution, and then spray-dried.

  In any of the melt-kneading method, the suspension polymerization method, and the spray-drying method, a magnetic powder is prepared in advance by some means, the magnetic powder and a resin solution are mixed, and the resin solution is mixed in the resin solution. A step of dispersing the magnetic powder.

<Coating layer>
The carrier in this embodiment has a magnetic core material and a coating layer that covers the magnetic core material.
The coating layer preferably contains at least a resin.
A general resin can be used as the resin (matrix resin) contained in the coating layer. For example, polyolefin resins such as polyethylene and polypropylene; polystyrene and acrylic resins, polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl carbazole, polyvinyl ether, polyvinyl ketone and other polyvinyl and polyvinylidene resins; Vinyl-vinyl acetate copolymer; Styrene-acrylic acid copolymer; Straight silicone resin composed of organosiloxane bond or modified product thereof; Fluorine such as polytetrafluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, polychlorotrifluoroethylene, etc. Polyester; Polyurethane; Polycarbonate; Phenol resin; Urea-formaldehyde resin, melamine resin, benzoguanamine resin, resin A resin, amino resins such as polyamide resins; silicone resins; epoxy resins.
These may be used individually by 1 type and may use 2 or more types together.

In particular, for contamination of the toner component, it is preferable to use a low surface energy resin such as a fluororesin or a silicone resin as a coating resin, and it is more preferable to coat with a fluororesin.
Examples of fluororesins include fluoropolyolefins, fluoroalkyl (meth) acrylate polymers and / or copolymers, vinylidene fluoride polymers and / or copolymers, and mixtures thereof, and form fluororesins. Fluorine-containing monomers such as tetrafluoropropyl methacrylate, pentafluoromethacrylate, octafluoropentyl methacrylate, perfluorooctylethyl methacrylate, trifluoroethyl methacrylate, etc. Is preferred. However, it is not limited to these.
As a compounding quantity of the monomer containing a fluorine, it is preferable to mix | blend in the range of 0.1-50.0 mass% with respect to all the monomers which comprise coating resin, and 0.5-40. The range is more preferably 0% by mass, and still more preferably 1.0 to 30.0% by mass. If it is in the above range, the contamination resistance can be sufficiently secured, the adhesion of the coating resin to the core material is sufficient, and the charging property is also excellent.

The coating layer can contain resin particles dispersed therein.
Examples of the resin particles include thermoplastic resin particles and thermosetting resin particles. Among these, thermosetting resins that are relatively easy to increase the hardness are suitable, and in order to impart negative chargeability to the toner, it is preferable to use resin particles containing nitrogen atoms. In addition, these resin particles may be used individually by 1 type, and may use 2 or more types together.
The resin particles are preferably dispersed as uniformly as possible in the thickness direction of the coating layer and in the tangential direction to the carrier surface in the matrix resin of the coating layer. It is preferable that the resin of the resin particles and the matrix resin have high compatibility because the uniformity of dispersion in the coating layer of the resin particles is improved.

  Examples of the thermoplastic resin include polyolefin resins such as polyethylene and polypropylene; polyvinyl resins such as polystyrene, acrylic resin, polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl carbazole, polyvinyl ether, and polyvinyl ketone. Resin and polyvinylidene resin; vinyl chloride-vinyl acetate copolymer; styrene-acrylic acid copolymer; straight silicone resin composed of organosiloxane bond or modified product thereof; polytetrafluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, Fluorine resin such as polychlorotrifluoroethylene; polyester; polyurethane; polycarbonate and the like.

Examples of the thermosetting resin used for the resin particles include phenol resins; urea-formaldehyde resins, melamine resins, silicone resins, benzoguanamine resins, urea resins, polyamide resins, and other amino resins; epoxy resins; and the like.
The resin of the resin particles and the matrix resin may be the same material or different materials. Particularly preferably, the resin of the resin particles and the matrix resin are made of different materials.

It is preferable to use thermosetting resin particles as the resin of the resin particles because the mechanical strength of the carrier can be improved. A resin having a crosslinked structure is particularly preferable. Further, in order to improve the function of the resin particle as a charging site, it is preferable to use a resin having a quick rise in toner charging. Examples of such resin particles include nylon resin, amino resin, and melamine resin. Nitrogen-containing resin particles are preferred.
Resin particles are produced by a method of producing granulated resin particles using polymerization such as emulsion polymerization or suspension polymerization, or by granulating while a monomer or oligomer is dispersed in a solvent and a crosslinking reaction proceeds. Manufactured by a method of producing particles, a low molecular component and a crosslinking agent are mixed and reacted by melt kneading, etc., and then pulverized to a predetermined particle size by wind, mechanical force, etc. to produce resin particles can do.

The volume average particle diameter of the resin particles is preferably 0.1 to 2.0 μm, and more preferably 0.2 to 1.0 μm. Within the above range, the dispersibility in the coating layer is excellent, and the resin particles do not easily fall off from the coating layer, and a stable chargeability can be obtained.
The method for measuring the volume average particle diameter of the resin particles is the same as that for the volume average particle diameter of the core material.
The resin particles are preferably contained in the coating layer at 1 to 50% by volume, more preferably 1 to 30% by volume, and even more preferably 1 to 20% by volume. When the content ratio of the resin particles in the coating layer is within the above range, the effect of the resin particles can be sufficiently exhibited, and the resin particles are not easily detached from the coating layer, and stable chargeability is obtained.

The coating layer may further contain a conductive powder dispersed therein.
Examples of the conductive powder include metals such as gold, silver, and copper; carbon black; and titanium oxide, magnesium oxide, zinc oxide, aluminum oxide, calcium carbonate, aluminum borate, potassium titanate, and calcium titanate powder. Metal oxides such as titanium oxide, zinc oxide, barium sulfate, aluminum borate, potassium titanate powder, etc. The surface of the powder is covered with tin oxide, carbon black, or metal; These may be used alone or in combination of two or more.
It is preferable to use a metal oxide as the conductive powder because the environmental dependency of the charging property can be further reduced, and titanium oxide is particularly preferable.

Furthermore, it is preferable to treat the powder made of the material with a coupling agent. Of these, metal oxides treated with a coupling agent are preferred, and titanium oxide treated with a coupling agent is particularly preferred.
The conductive powder treated with the coupling agent can be obtained by dispersing untreated conductive powder in a solvent such as toluene, then mixing and treating the coupling agent, and then drying under reduced pressure.
Furthermore, in order to remove aggregates from the conductive powder treated with the obtained coupling agent, it may be crushed by a crusher as necessary.
As the crusher, known crushers such as a pin mill, a disk mill, a hammer mill, a centrifugal classification mill, a roller mill, and a jet mill can be used, and a jet mill is particularly preferable.
As the coupling agent to be used, known ones such as a silane coupling agent, a titanium coupling agent, an aluminum coupling agent, and a zirconium coupling agent can be used.
Among these, use of a silane coupling agent, particularly conductive powder treated with methyltrimethoxysilane, is particularly effective for the environmental stability of charging.

The volume average particle size of the conductive powder is preferably 0.5 μm or less, more preferably 0.05 μm or more and 0.45 μm or less, and further preferably 0.05 μm or more and 0.35 μm or less. When the volume average particle diameter of the conductive powder is in the above range, the resin particles are unlikely to fall off from the coating layer, and stable chargeability is obtained.
The method for measuring the volume average particle size of the conductive powder is in accordance with the method for measuring the volume average particle size of the core material.

The conductive powder preferably has a volume electrical resistance of 10 ¹ Ω · cm to 10 ¹¹ Ω · cm, and preferably 10 ³ Ω · cm to 10 ⁹ Ω · cm. More preferably. In addition, in this specification, the volume electrical resistance of electroconductive powder means the value measured with the following method.
Under the condition of 22 ° C. and 55% RH, the conductive powder is filled into a container having a cross-sectional area of 2 × 10 ⁻⁴ m ² to a thickness of about 1 mm, and then, on the filled conductive powder, A load of 1 × 10 ⁴ kg / m ² is applied by a metal member. A voltage that generates an electric field of 10 ⁶ V / m is applied between the metal member and the bottom electrode of the container, and a value calculated from the current value at that time is defined as a volume electric resistance value.

  The conductive powder is preferably contained in the coating layer in an amount of 1 to 80% by volume, more preferably 2 to 20% by volume, and still more preferably 3 to 10% by volume.

As a method of forming the coating layer on the surface of the core material of the carrier, a coating layer forming solution containing the resin, conductive material and solvent is prepared, and a dipping method in which the core material particles are immersed therein, or a coating layer Spray method of spraying the forming solution onto the surface of the core particle, fluidized bed method of spraying the coating layer forming solution in a state where the core particle is suspended by the flowing air, or the core particle and the coating layer in a kneader coater Examples thereof include a kneader coater method in which a solvent is removed by mixing with a forming solution.
The solvent used for preparing the coating layer forming solution is not particularly limited as long as it dissolves the resin. For example, aromatic hydrocarbons such as toluene and xylene, ketones such as acetone and methyl ethyl ketone, and the like. And ethers such as tetrahydrofuran and dioxane can be used.

The coverage of the core material by the coating layer in the carrier used in the present embodiment is not particularly limited, but is preferably 90% or more, more preferably 95% or more, and 97% or more and 100% or less. More preferably it is.
In the present embodiment, the covering ratio of the core material is determined by measuring the constituent element ratios of the surfaces of the core material (without coating) and the carrier (with coating) using an X-ray photoelectron spectrometer (XPS). It is preferable that it is a value represented by.
Coverage (%) = {1− (peak area attributed to magnetic metal of carrier) / (peak area attributed to magnetic metal of core)} × 100
In addition, since the measured value of the coverage with XPS correlates with the resin coverage detected by image processing using a microscope or the like, the coverage can be obtained by an image processing method.

The average film thickness of the coating layer is preferably 0.1 to 10 μm, more preferably 0.1 to 3.0 μm, and still more preferably 0.1 to 1.0 μm. When the average film thickness of the coating layer is in the above range, the coating layer is less peeled even when used for a long time, the resistance decrease can be further suppressed, and the carrier pulverization can be sufficiently controlled. The time to reach the saturation charge amount is sufficiently short.
Further, the coating amount of the carrier is preferably 3 to 20% by mass, more preferably 3 to 10% by mass, and further preferably 3 to 6% by mass with respect to the mass of the carrier core. . When the carrier coating amount is in the above range, the toner can be sufficiently charged, and fogging in the non-image area after development and fixing can be suppressed.

The specific gravity of the carrier used in the present embodiment, is preferably 3.8 g / cm ³ or less, and more preferably 3~3.8g / cm ^3. When the specific gravity is within the above range, the agitation stress applied to the toner in the developing machine is reduced by reducing the specific gravity. It is possible to suppress fogging in the part.
In this embodiment, the saturation magnetization of the carrier is preferably 40 emu / g or more, and more preferably 50 emu / g or more.
As a device for measuring magnetic properties, a vibrating sample type magnetic measuring device VSMP10-15 (manufactured by Toei Industry Co., Ltd.) is used. The measurement sample is packed in a cell having an inner diameter of 7 mm and a height of 5 mm and set in the apparatus. The measurement applies an applied magnetic field and sweeps up to 1,000 oersted. Next, the applied magnetic field is reduced to create a hysteresis curve on the recording paper. Saturation magnetization, residual magnetization, and coercive force are obtained from the curve data. In the present embodiment, the saturation magnetization indicates the magnetization measured in a 1,000 oersted magnetic field.

The volume electrical resistivity of the carrier is preferably 1.0 × 10 ⁹ Ω · cm or more, more preferably 1.0 × 10 ⁹ to 1 × 10 ¹⁵ Ωcm, and 1.0 × 10 ^9. It is more preferably ⁹ to 1 × 10 ¹⁴ Ωcm, and particularly preferably 1.0 × 10 ⁹ to 1 × 10 ¹³ Ωcm. When the volume resistivity of the carrier is in the above range, it works sufficiently as a developing electrode during development, and can suppress the edge effect particularly in a solid image portion, has excellent solid reproducibility, and the toner concentration in the developer is reduced. Occasionally, charges are not injected from the developing roll into the carrier, and the carrier itself is not easily developed.

The volume electrical resistivity (Ω · cm) of the carrier in this embodiment is measured as follows. The measurement environment is a temperature of 20 ° C. and a humidity of 50% RH.
The carrier to be measured is placed flat on the surface of a circular jig having a 20 cm ² electrode plate so as to have a thickness of about 1 to 3 mm to form a carrier layer. A 20 cm ² electrode plate similar to the above is placed on this and the carrier layer is sandwiched. In order to eliminate the gap between the carriers, the thickness (cm) of the carrier layer is measured after a load of 4 kg is applied on the electrode plate placed on the carrier layer. An electrometer and a high-voltage power generator are connected to both electrodes above and below the carrier layer. A high voltage is applied to both electrodes so that the electric field is 10 ^3.8 V / cm, and the current value (A) flowing at this time is read to calculate the volume electrical resistivity (Ω · cm) of the carrier. The calculation formula of the volume electrical resistivity (Ω · cm) of the carrier is as shown in the following formula (1).
Formula (1): R = E × 20 / (I−I ₀ ) / L
In the above formula (1), R is the volume resistivity of the carrier (Ω · cm), E is the applied voltage (V), I is the current value (A), I ₀ is the current value (A) at an applied voltage of 0 V, L represents the thickness (cm) of the carrier layer. The coefficient “20” represents the area (cm ² ) of the electrode plate.

The mixing ratio (mass ratio) of the carrier and the toner in the electrostatic image developer of the exemplary embodiment is preferably in the range of toner: carrier = 1: 99 to 20:80, and is 3:97 to 12:88. A range is more preferable.
The mixing method of the carrier and the toner is not particularly limited, and can be mixed by a known apparatus or method such as a V blender.

(Image forming method)
An image forming method using the electrostatic charge image developer of this embodiment will be described. The electrostatic charge image developer of this embodiment is used in an image forming method using a known electrophotographic system. Specifically, it is used in an image forming method having the following steps.
That is, a preferable image forming method includes at least a charging step for charging the image carrier, an exposure step for forming an electrostatic latent image on the surface of the image carrier, and an electrostatic latent image formed on the surface of the image carrier. A developing step of developing with an electrostatic charge image developer to form a toner image, a transferring step of transferring the toner image formed on the surface of the image carrier to the surface of the transfer target, and a fixing step of fixing the toner image; The developer is the electrostatic charge image developer of this embodiment. Further, the transfer step may use an intermediate transfer member that mediates transfer of the toner image from the electrostatic latent image holding member to the transfer target.
It is also preferable to have a cleaning step for removing residual toner on the surface of the image carrier after transfer.

Each of the above steps is a general step per se, and is described in, for example, JP-A-56-40868 and JP-A-49-91231. Note that the image forming method of the present embodiment can be carried out by using a known image forming apparatus such as a copying machine or a facsimile machine.
The electrostatic latent image forming step is a step of forming an electrostatic latent image on an image carrier (photoconductor).
The developing step is a step of developing the electrostatic latent image with a developer layer on a developer holding member to form a toner image. The developer layer is not particularly limited as long as it contains the electrostatic image developer of this embodiment.
The transfer step is a step of transferring the toner image onto a transfer target. Examples of the transfer medium in the transfer process include an intermediate transfer medium and a recording medium such as paper.
In the fixing step, for example, there is a method of forming a copy image by fixing the toner image transferred onto the transfer paper by a heating roller fixing device in which the temperature of the heating roller is set to a constant temperature.
The cleaning step is a step of removing the electrostatic charge image developer remaining on the image carrier.
As the transfer target, a recording medium such as an intermediate transfer member or paper can be used.
Examples of the recording medium include paper used for electrophotographic copying machines and printers, OHP sheets, etc., for example, coated paper whose surface is coated with resin, art paper for printing, and the like. Etc. can be used suitably.

  The image forming method of the present embodiment may further include a recycling step. The recycling step is a step of transferring the electrostatic charge image developing toner collected in the cleaning step to a developer layer. The image forming method including the recycling process is performed using an image forming apparatus such as a toner recycling system type copying machine or facsimile machine. Further, the present invention may be applied to a recycling system in which the cleaning process is omitted and toner is collected simultaneously with development.

(Image forming device)
The image forming apparatus of this embodiment will be described with reference to an image forming apparatus using the electrostatic charge image developer of this embodiment.
The image forming apparatus according to the present embodiment includes an image carrier, a charging unit that charges the image carrier, and an exposure unit that exposes the charged image carrier to form an electrostatic latent image on the image carrier. A developing unit that develops the electrostatic latent image with a developer to form a toner image, a transfer unit that transfers the toner image from the image holding member to a transfer target, and a fixing unit that fixes the toner image. It is preferable that the developer is the electrostatic image developer of this embodiment.
The image forming apparatus of the present embodiment is not particularly limited as long as it includes at least the image carrier, the charging unit, the exposure unit, the developing unit, the transfer unit, and the fixing unit as described above. Although not necessary, a cleaning means, a static elimination means, and the like may be included as necessary.
In the transfer unit, the transfer may be performed twice or more using an intermediate transfer member. Examples of the transfer medium in the transfer unit include an intermediate transfer medium and a recording medium such as paper.

The image carrier and each of the above-described units can preferably use the configurations described in the respective steps of the image forming method. As each of the above-described means, a known means in the image forming apparatus can be used. In addition, the image forming apparatus according to the present embodiment may include means and devices other than the above-described configuration. Further, the image forming apparatus according to the present embodiment may simultaneously perform a plurality of the above-described means.
The image forming apparatus according to the present exemplary embodiment preferably includes a cleaning unit that removes the electrostatic charge image developer remaining on the image carrier.
Examples of the cleaning means include a cleaning blade and a cleaning brush, and a cleaning blade is preferable.

  In this image forming apparatus, for example, the part including the developing unit may be a cartridge structure (process cartridge) that is detachable from the main body of the image forming apparatus. As the process cartridge, a developer holding body is used. The process cartridge of the present embodiment is preferably used that includes at least the electrostatic charge image developing developer of the present embodiment.

(Developer cartridge and process cartridge)
The developer cartridge of this embodiment is a developer cartridge that contains at least the electrostatic charge image developer of this embodiment.
The process cartridge of the present embodiment is a process cartridge including a developer holder that contains the electrostatic charge image developer of the present embodiment and holds and conveys the electrostatic charge image developer. Developing means for developing an electrostatic latent image formed on the surface with the electrostatic charge image developer to form a toner image, an image carrier, a charging means for charging the surface of the image carrier, and And at least one selected from the group consisting of cleaning means for removing toner remaining on the surface of the image carrier, and a process cartridge containing at least the electrostatic charge image developer of the present embodiment. preferable.

The developer cartridge of this embodiment is not particularly limited as long as it contains the electrostatic charge image developer of this embodiment. For example, the developer cartridge is attached to or detached from an image forming apparatus including a developing unit, and the electrostatic image developer including the electrostatic image developing toner of the present embodiment is used as a developer to be supplied to the developing unit. It is what is stored.
The developer cartridge may be a cartridge that stores toner and a carrier, or may be a cartridge that stores toner alone and a cartridge that stores a carrier separately.
It is preferable that the process cartridge of the present embodiment is attached to and detached from the image forming apparatus.
In addition, the process cartridge according to the present embodiment may include other members such as a static elimination unit as necessary.
As the process cartridge, a known configuration may be adopted. For example, Japanese Patent Application Laid-Open No. 2008-209489 and Japanese Patent Application Laid-Open No. 2008-203736 are referred to.

  Hereinafter, the present embodiment will be described in detail with reference to examples. However, the present embodiment is not limited only to the following examples. In the following description, “parts” means “parts by mass” unless otherwise specified. In addition, “primary particle size” in the following represents “volume average primary particle size”.

<Measuring method of average crystallite diameter of metatitanic acid particles>
The peak of the (101) plane of the metatitanic acid particles is measured by powder X-ray diffraction method, and the average value L of the crystallite diameter can be obtained from the following formula (1) of Scherrer. Crystallite diameter.
L = Kλ / (βcos θ) (1)
Here, K is a constant, λ is a wavelength, β is a half width, and θ is an incident angle.

<Measuring method of weight loss in thermogravimetric analysis (TGA) of metatitanic acid particles of 100 ° C. to 500 ° C.>
When using a thermogravimetric analysis (TGA) measuring device (device name: DTG-60AH, manufacturer: Shimadzu Corporation), the temperature is increased from 30 ° C. to 30 ° C./min in a nitrogen gas atmosphere. The mass change amount at 100 ° C. to 500 ° C. was measured and used as a weight loss in thermogravimetric analysis (TGA).

<Preparation of metatitanic acid particles 1>
Using ilmenite as an ore, TiO (OH) ₂ was produced using a wet precipitation method in which iron powder was separated by dissolving in sulfuric acid and TiOSO ₄ was hydrolyzed to produce TiO (OH) ₂ . In the process of producing TiO (OH) ₂ , dispersion adjustment and water washing for hydrolysis and nucleation were performed.
During the water washing, the mixture was stirred with 10 ppm polycarboxylic acid and water based on the solid content after washing. By using polycarboxylic acid, it is considered that oxidation is moderate and crystal growth is also moderate.
The obtained TiO (OH) ₂ was dried at 150 ° C., then at 800 ° C. for 1 minute (hereinafter referred to as one-stage firing temperature and time) and at 500 ° C. for 60 minutes (hereinafter referred to as two-stage firing temperature and It is time.) Baking. Subsequently, 100 mass parts was disperse | distributed in 1,000 mass parts of water, and 5 mass parts of isobutyltrimethoxysilane was dripped at this at room temperature (25 degreeC) stirring. Subsequently, this was filtered and water washing was repeated. Metatitanic acid particles whose surface has been hydrophobized with isobutyltrimethoxysilane are dried at 150 ° C., and the weight loss of TGA having a crystallite size of 14.0 nm and not lower than 100 ° C. and lower than 500 ° C. is 1.5% by mass. Was prepared.

<Production of metatitanic acid particles 2 to 10>
In the production of the metatitanic acid particles 1, metatitanic acid particles 2 to 10 were produced in the same manner except that the amount of polycarboxylic acid and the firing conditions shown in Table 1 were changed.

<Preparation of Toner 1>
<< Preparation of toner mother particles >>
-Preparation of polyester resin dispersion-
-Ethylene glycol (Wako Pure Chemical Industries, Ltd.): 37 parts-Neopentyl glycol (Wako Pure Chemical Industries, Ltd.): 65 parts-1,9-nonanediol (Wako Pure Chemical Industries, Ltd.) : 32 parts terephthalic acid (manufactured by Wako Pure Chemical Industries, Ltd.): 96 parts The above monomer was charged into a flask and raised to a temperature of 200 ° C over 1 hour, confirming that the reaction system was uniformly stirred. Thereafter, 1.2 parts of dibutyltin oxide was added. Further, while distilling off the generated water, the temperature was increased from the same temperature to 240 ° C. over 6 hours, and the dehydration condensation reaction was continued at 240 ° C. for another 4 hours. The acid value was 9.4 mgKOH / g, and the weight average molecular weight. A polyester resin having 13,000 and a glass transition point of 62 ° C. was obtained.
Subsequently, this was transferred in a molten state to Cavitron CD1010 (manufactured by Eurotech Co., Ltd.) at a rate of 100 parts per minute. A 0.37% diluted aqueous ammonia solution obtained by diluting reagent ammonia water with ion-exchanged water is put into a separately prepared aqueous medium tank, and the polyester is heated at 120 ° C. with a heat exchanger at a rate of 0.1 liter per minute. Simultaneously with the resin melt, it was transferred to the Cavitron. The Cavitron was operated under the conditions of a rotor rotation speed of 60 Hz and a pressure of 5 kg / cm ^2. Resin particles having an average particle diameter of 160 nm, a solid content of 30%, a glass transition point of 62 ° C., and a weight average molecular weight Mw of 13,000 were obtained. A dispersed amorphous polyester resin dispersion was obtained.

-Preparation of colorant dispersion-
-Cyan pigment (Pigment Blue 15: 3, manufactured by Dainichi Seika Kogyo Co., Ltd.): 10 parts-Anionic surfactant (Neogen SC, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.): 2 parts-Ion-exchanged water: 80 parts These components were mixed and dispersed for 1 hour with a high-pressure impact disperser Ultimizer [HJP30006, manufactured by Sugino Machine Co., Ltd.] to obtain a colorant dispersion having a volume average particle size of 180 nm and a solid content of 20%.

-Preparation of release agent dispersion-
-Paraffin wax [HNP 9, Nippon Seiwa Co., Ltd.]: 50 parts-Anionic surfactant [Neogen SC, Daiichi Kogyo Seiyaku Co., Ltd.]: 2 parts-Ion-exchanged water: 200 parts Heat to 120 ° C., thoroughly mix and disperse with IKA's Ultra Turrax T50, then disperse with a pressure discharge homogenizer, and release agent dispersion with a volume average particle size of 200 nm and a solid content of 20% Got.

-Production of toner base particles 1-
-Polyester resin dispersion: 200 parts-Colorant dispersion: 25 parts-Release agent dispersion: 25 parts-Polyaluminum chloride: 0.4 parts-Ion exchange water: 100 parts Add the above ingredients into a stainless steel flask After thoroughly mixing and dispersing using IKA's Ultra Turrax, the flask was heated to 48 ° C. with stirring in an oil bath for heating. After maintaining at 48 ° C. for 30 minutes, 70 parts of the same polyester resin dispersion as above was gently added thereto.
Then, after adjusting the pH in the system to 8.0 using a sodium hydroxide aqueous solution having a concentration of 0.5 mol / L, the stainless steel flask is sealed, and the stirring shaft seal is magnetically sealed while stirring is continued. Heat to 90 ° C. and hold for 3 hours. After completion of the reaction, the temperature lowering rate was cooled at 2 ° C./min, filtered, sufficiently washed with ion exchange water, and then subjected to solid-liquid separation by Nutsche suction filtration. This was further redispersed using 3,000 parts of ion exchange water at 30 ° C., and stirred and washed at 300 rpm for 15 minutes. This washing operation was further repeated 6 times. When the pH of the filtrate became 7.54 and the electric conductivity was 6.5 μS / cm, No. 2 was obtained by Nutsche suction filtration. Solid-liquid separation was performed using 5A filter paper. Next, vacuum drying was continued for 12 hours to obtain toner base particles 1.
The number average particle diameter of the toner base particles 1 was measured with a Coulter Multisizer-II type (manufactured by Beckman Coulter, Inc.) and found to be 5.8 μm and SF1 was 130.

<< Production of Toner 1 >>
Further, 1.0% by mass of silica (SiO ₂ ) particles having a primary particle average particle size of 100 nm, which has been subjected to surface hydrophobization treatment with hexamethyldisilazane (hereinafter sometimes abbreviated as “HMDS”), is used as the toner base particles 1. Then, 1.0% by mass of metatitanic acid particles 1 were added and mixed with a Henschel mixer to obtain toner 1.

<Preparation of Toners 2 to 12>
Toners 1 to 12 were prepared in the same manner except that the amount of metatitanic acid particles and the amount of metatitanic acid particles added in Table 2 were changed.

<Preparation of Toner 13>
-Preparation of resin particle dispersion (2)-
320 parts of styrene, 80 parts of n-butyl acrylate, 8 parts of acrylic acid, and 6.5 parts of dodecanethiol were mixed and dissolved in an anionic surfactant (Neogen SC: manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 5 Part of the mixture was emulsion-polymerized in a flask in which 550 parts of ion-exchanged water had been dissolved, and 60 parts of ion-exchanged water in which 5 parts of ammonium persulfate had been dissolved was added thereto while slowly mixing for 60 minutes. After carrying out nitrogen substitution, the inside of the flask was stirred and heated in an oil bath until the content reached 80 ° C., and emulsion polymerization was continued for 6 hours. Then, it cooled and solid content was set to 30% and the resin particle dispersion liquid (2) was obtained.

-Preparation of toner base particles 2-
A colorant dispersion, a release agent dispersion, 0.4 parts of polyaluminum chloride, and ion-exchanged water are added in the same manner as in the preparation of the toner base particles 1 except that the polyester resin dispersion is changed to the resin particle dispersion (2). Then, the same treatment was performed to add the resin particle dispersion (2).
Thereafter, the pH of the system was adjusted to 5.5-6 using a 0.5 mol / L sodium hydroxide aqueous solution and a 0.5 mol / L nitric acid aqueous solution as appropriate, and then the stainless steel flask was sealed and a stirring shaft The seal was magnetically sealed and heated to 94 ° C. with continued stirring and held for 5 hours. After completion of the reaction, the cooling rate was cooled at 2 ° C./min. Thereafter, washing and drying were performed in the same manner as toner base particles 1, and toner base particles 2 were obtained.
The number average particle diameter of the toner base particles 2 is 5.5 μm, and SF1 is 128.

-Production of Toner 13-
Further, an external additive similar to that of toner 1 was added to toner base particles 2 and mixed to obtain toner 13.

<Preparation of Toners 14 to 24>
Toners 13 to 24 were prepared in the same manner except that the amount of metatitanic acid particles and the amount of metatitanic acid particles shown in Table 2 were changed.

<Preparation of Toner 25>
Toner 1 was prepared in the same manner as toner 1 except that silica particles were not added.

<Preparation of Toner 26>
A toner 26 was produced in the same manner as in the production of the toner 13 except that silica particles were not added in the production of the toner 13.

<Preparation of carrier 1>
1,000 parts of Mn—Mg ferrite (volume average particle diameter: 50 μm, manufactured by Powder Tech Co., Ltd., shape factor SF1: 120) were added to a kneader, and a perfluorooctylmethyl acrylate-methyl methacrylate copolymer (polymerization ratio (polymerization ratio ( (Molar ratio): 20/80, weight average molecular weight: 72,000] A solution in which 150 parts were dissolved in 700 parts of toluene was added, mixed at room temperature (25 ° C) for 20 minutes, then heated to 70 ° C and dried under reduced pressure. Thereafter, the carrier was taken out to obtain a carrier (coated carrier) in which the magnetic core material was coated with a coating layer, and the obtained coated carrier was sieved with a mesh having a mesh opening of 75 μm to remove coarse powder, thereby obtaining a carrier. The shape factor SF1 was 122.

<Production of Carrier 2>
1,000 parts of Mn—Mg ferrite (volume average particle size: 50 μm, manufactured by Powder Tech Co., Ltd., shape factor SF1: 120) were added to a kneader, and cyclohexyl acrylate resin, weight average molecular weight: 50,000] 100 parts. A solution dissolved in 700 parts of toluene is added, mixed at room temperature (25 ° C.) for 20 minutes, heated to 70 ° C., dried under reduced pressure, taken out, and a carrier in which the magnetic core is coated with a coating layer (coated carrier) Got. Furthermore, the obtained coated carrier was sieved with a mesh having an opening of 75 μm, and coarse powder was removed to obtain a carrier. The carrier shape factor SF1 was 124.

Example 1
<Preparation of electrostatic charge image developer>
As shown in Table 3, each obtained toner and each carrier are put in a V blender at a ratio of toner: carrier = 8: 92 (mass ratio), stirred for 20 minutes, and each electrostatic image developer is added. Obtained.

<Evaluation of carrier resistance after continuous image formation>
The volume resistance of the carrier separated from the toner after the continuous image formation is such that two electrode plates face each other in parallel with a width of 1 mm, and 0.25 parts by mass of the carrier is placed between them, held by a magnet, and an applied voltage of 500 V The current value was measured and calculated from the obtained current value.

<Evaluation for suppressing adhesion of carrier to photoconductor and evaluation for suppressing stain on developing machine>
The developer obtained in the Docu Center Color 400 remodeled machine (Fuji Xerox Co., Ltd.) is filled with the obtained developer, and at a high temperature and high humidity (30 ° C., 85% RH), first, a halftone with an image density of 5% After the entire surface image was output continuously for 10,000 sheets, a patch of 5 cm × 5 cm having an image density of 100% was formed on the 10,000th sheet. Next, 10,000 full-tone half-tone images with an image density of 25% were output continuously.
The image of the 10,001th sheet was observed with an optical microscope, and the occurrence of carrier adhesion to the photoreceptor was confirmed.
Evaluation criteria for evaluating the carrier adhesion to the photoreceptor are shown below.
◎: The number of carriers developed in the patch is 2 or less ○: The number of carriers developed in the patch is 3 or more and 5 or less △: The number of carriers developed in the patch is 6 or more and 10 X: The number of carriers developed in the patch is 11 or more. Toner contamination around the developing machine after the 10,000th sheet was output was visually confirmed.
The evaluation criteria for the evaluation of the developer stain resistance are shown below.
◎: No developing device contamination ○: Some of the developing device contamination can be confirmed △: The developing device contamination can be confirmed as a whole, but other developing devices in the modified machine are not contaminated ×: The developing device contamination can be confirmed as a whole Dirty other developing machines in the modified machine

(Examples 2 to 20 and Comparative Examples 1 to 8)
In the production of the electrostatic charge image developer of Example 1, the electrostatic charge image developers of Examples 2 to 20 and Comparative Examples 1 to 8 were prepared in the same manner except that the toners and carriers described in Table 3 were changed. Were prepared. Each of the obtained electrostatic charge image developers was evaluated in the same manner as in Example 1. The evaluation results are summarized in Table 3.

Claims (4)

Toner base particles containing at least a binder resin and an external additive having a crystallite diameter of 12.0 nm to 16.0 nm and a weight loss in thermogravimetric analysis of 100 ° C. to 500 ° C. of 0.5 ° C. A toner containing metatitanic acid particles in an amount of not less than 2.5% by mass and not more than 2.5% by mass;
An electrostatic charge image developer comprising: a magnetic core material; and a carrier having a coating layer that covers the magnetic core material.   The electrostatic charge image developer according to claim 1, wherein the content of the metatitanic acid particles is 0.3% by mass or more and 2% by mass or less based on the total mass of the toner. A charging step for charging at least the image carrier;
An exposure step of forming an electrostatic latent image on the surface of the image carrier;
A developing step of developing the electrostatic latent image formed on the surface of the image carrier with an electrostatic charge image developer to form a toner image;
A transfer step of transferring the toner image formed on the surface of the image carrier to the surface of the transfer target;
A fixing step of fixing the toner image,
The image forming method according to claim 1, wherein the developer is the electrostatic charge image developer according to claim 1. An image carrier,
Charging means for charging the image carrier;
Exposure means for exposing the charged image carrier to form an electrostatic latent image on the image carrier;
Developing means for developing the electrostatic latent image with a developer to form a toner image;
Transfer means for transferring the toner image from the image carrier to a transfer medium;
Fixing means for fixing the toner image,
An image forming apparatus, wherein the developer is the electrostatic charge image developer according to claim 1.