JP5516270B2 - Developer for developing electrostatic image, process cartridge, image forming apparatus and image forming method - Google Patents

Description

  The present invention relates to a developer for developing an electrostatic image, a process cartridge, an image forming apparatus, and an image forming method.

In image formation by electrophotography, an electrostatic charge image is formed on a latent image carrier (photoreceptor) by a charging process and an exposure process, developed in a developing process to form a developed image, and the developed image is transferred onto a recording medium. In the fixing step, the image is fixed by heating or the like. The developer for developing an electrostatic image used in such an electrophotographic method includes a one-component developer using a toner in which a colorant is dispersed in a binder resin, and a two-component developer composed of a toner and a carrier. It is divided roughly into.
The two-component developer has a relatively large surface area so that it can be easily charged with toner, and by using magnetic particles for the carrier, it can be easily conveyed by a mag roll or the like. Widely used.

In order to provide a two-component developing type electrophotographic developer free from filming or fogging, an electrostatic charge on a photoreceptor including a carrier containing a magnetic material powder, a toner containing a binder synthetic resin and a colorant. In the developer for electrophotography that develops a latent image, the saturation charge amount Qsd of the toner in the initial developer mixed with the carrier and the saturation charge amount Qsa of the replenishment toner have the following relationship: A two-component developing system electrophotographic developer characterized by the above is disclosed (for example, see Patent Document 1).
Qsd / Qsa ≦ 0.76

  In addition, in order to provide a developer for electrophotography that can withstand continuous high-speed copying for a long time, the dielectric constant is 2.5 or more with an electrophotographic carrier whose surface is coated with a silicone oil, a resin, and a silane coupling agent. An electrophotographic developer comprising a toner of 3.5 or less is disclosed (for example, see Patent Document 2).

In addition, in order to provide a carrier for developing an electrostatic latent image in which the toner charge amount rises quickly, carrier adhesion does not occur, a stable chargeability is given to the toner for a long time, and a good image can be stably obtained. In a carrier for developing an electrostatic latent image in which resin particles and metal oxide particles are dispersed in a coating resin layer on a magnetic core particle, the metal oxide particles have a dielectric constant of 5 × 10 ⁻¹¹ (F / m) In the range of 50 × 10 ^-11 (F / m) or less, and the electric resistance of the metal oxide particles exceeds 10 ⁸ (Ω · m), for electrostatic latent image development A carrier is disclosed (for example, see Patent Document 3).

Further, in order to provide an image forming method capable of forming a good image while preventing a defective paper discharge even when a toner containing carbon black is used, the surface of the photosensitive member holding an electrostatic latent image is charged A charging step for charging the toner, a latent image forming step for forming an electrostatic latent image on the surface of the charged photoreceptor, and a toner contained in a developer is supplied to the electrostatic latent image on the surface of the photoreceptor to supply the static image. In a nip formed by a developing process for visualizing an electrostatic latent image to form a toner image, a transfer process for transferring the toner image onto a transfer material, and a pressure member that is in pressure contact with the fixing body. And a fixing step in which the toner image is heated and contact-pressed onto the transfer material by passing the transfer material, and the image forming method in which the above steps are repeated to repeatedly perform image formation, Body is oil The toner includes a non-magnetic black toner having toner particles containing at least a binder resin, carbon black, and a release agent, and inorganic particles. The toner has a mass average particle diameter of 3.5 μm or more and 9.5 μm or less, and the loss tangent tan δ represented by (dielectric loss factor ε ″ / dielectric constant ε ′) of the toner is a frequency of 5 × 10 ⁴ Hz. And the toner has a weight average molecular weight (Mw) of 200,000 or more and 900,000 or less at a frequency of 10 ⁵ Hz. The fluidity index is 55 or more and 98 or less and the Kerr particle size index is 70 or more and 98 or less, and the release agent is 2 parts by mass or more in 100 parts by mass of the toner particles. An image forming method containing 20 parts by mass or less is disclosed (see, for example, Patent Document 4).

Further, in order to provide a new carrier with improved developability and image stability, the carrier comprises a magnetic core particle and a carrier coating material that coats the surface thereof, and the dielectric loss factor ε ″ / dielectric constant of the carrier The loss tangent tan δ represented by ε ′ is expressed by the following relational expressions: a / b <6.5 and 0.05 <c <20 [where a is the frequency DEFreq [Hz] at a measurement temperature of 30 ° C .: 1 × 10 is the DEloss value at ² o'clock, b is the frequency DEFreq [Hz] at a measurement temperature of 30 ° C: 1X10 ⁶ o'clock, and c is the frequency DEFreq [Hz] at a measurement temperature of 150 ° C: 1 x 10 ² It is a carrier characterized by satisfying “de- losing value of time” (see, for example, Patent Document 5).

In addition, in order to provide a two-component developer that is resistant to environmental fluctuations, stable in charging during durability, and resistant to carrier deterioration, the first toner particles and the first external additive containing at least a binder resin and a colorant -Component development used in a development method having at least a first toner containing a first toner and a first magnetic carrier, and developing while replenishing a replenisher containing a second toner and a second magnetic carrier In the agent, the first toner contains at least 0.5 parts by mass of first silica particles having a number average particle diameter of 50 nm or more with respect to 100 parts by mass of the first toner particles, and the two-component developer. in the loss tangent tanδ represented by the dielectric loss factor epsilon "/ dielectric constant epsilon ', NiNaru loss tangent tanδ1 and 2 × ¹⁰ 5 Hz of the loss tangent tanδ2 frequency 2000Hz is characterized by satisfying the following formula System developer has been disclosed (e.g., refer to Patent Document 6).
0.06 ≦ tan δ1 (2000 Hz) ≦ 0.13
0.04 ≦ tan δ2 (2 × 10 ⁵ Hz) ≦ 0.10

Japanese Patent Application Laid-Open No. 09-258482 JP-A-10-020563 JP 2000-112183 A JP 2004-029156 A JP 2005-257993 A JP 2005-316057 A

  An object of the present invention is to provide a developer for developing an electrostatic charge image in which the occurrence of fogging in an initial output image after being left for a long time under high temperature and high humidity is suppressed.

That is, the invention according to claim 1 is a developer including a carrier and a toner,
When the concentration of the toner with respect to the developer is 8% by mass, the developer for developing an electrostatic charge image has a relative dielectric constant ε ′ of 12 or more and 22 or less and tan δ of 0.01 or more and 0.07 or less. .

The invention according to claim 2 is a resin-coated carrier in which the carrier has a magnetic core material and a resin coating layer that covers the magnetic core material,
The magnetic core material includes ferrite represented by the following formula (1), and the content of Si, Sr or Ti in the magnetic core material is 0.05 mol or more and 0.4 mol or less with respect to 1 mol of Fe. The developer for developing an electrostatic image according to claim 1.
(MO) _X (Fe ₂ O ₃ ) _Y formula (1)
[In Formula (1), Y represents 2.1 or more and 2.4 or less, and X represents 3-Y. M represents a metal element, and contains at least Mn as the metal element. ]

According to a third aspect of the present invention, in the static magnetic core according to the second aspect, the volume average particle diameter D50 (μm) and the BET specific surface area A (m ² / g) of the magnetic core material satisfy the following formula (2). It is a developer for developing a charge image.
0.003 ≦ A / D50 ≦ 0.011 Formula (2)

  The invention according to claim 4 is the developer for developing an electrostatic image according to any one of claims 1 to 3, wherein the toner contains a crystalline polyester resin.

The invention according to claim 5 is characterized in that the toner is
An agglomerated particle forming step of forming an agglomerated particle by adding an aggregating agent to a mixed dispersion obtained by mixing at least a binder resin particle dispersion in which a binder resin particle is dispersed and a colorant dispersion in which a colorant is dispersed;
An attaching step of further adding the binder resin particle dispersion to the mixed dispersion in which the aggregated particles are formed, and attaching the binder resin particles to the surface of the aggregated particles to form resin-attached aggregated particles; ,
A fusion step of fusing the resin-adhered aggregated particles by heating;
5. The developer for developing an electrostatic charge image according to claim 1, comprising toner particles produced through the process described above.

  The invention according to claim 6 is a process cartridge including at least a developer holder and containing the developer for developing an electrostatic charge image according to any one of claims 1 to 5.

  According to a seventh aspect of the present invention, there is provided a latent image holding member, a charging unit that charges the surface of the latent image holding member, an electrostatic charge image forming unit that forms an electrostatic charge image on the surface of the latent image holding member, and the electrostatic charge. A developing unit for developing the image with the developer for developing an electrostatic image according to any one of claims 1 to 5 to form a toner image; a transfer unit for transferring the toner image to a recording medium; An image forming apparatus comprising: a fixing unit that fixes the toner image on the recording medium.

  According to an eighth aspect of the present invention, there is provided a charging step of charging the surface of the latent image holding member, an electrostatic charge image forming step of forming an electrostatic charge image on the surface of the latent image holding member, and the electrostatic charge image. Item 6. A developing step of developing with the electrostatic charge image developing developer according to any one of Items 5 to form a toner image, a transferring step of transferring the toner image to a recording medium, and the toner image on the recording medium. A fixing step for fixing the image.

  According to the first aspect of the present invention, there is provided a developer for developing an electrostatic charge image in which the occurrence of fogging in an initial output image after being left for a long time under high temperature and high humidity is suppressed.

  According to the invention which concerns on Claim 2, generation | occurrence | production of fog is further suppressed compared with the case where it does not have this structure.

  According to the invention of claim 3, the occurrence of fog is further suppressed as compared with the case where the present configuration is not provided.

  According to the invention which concerns on Claim 4, generation | occurrence | production of fog is further suppressed compared with the case where it does not have this structure.

  According to the invention which concerns on Claim 5, generation | occurrence | production of fog is further suppressed compared with the case where it does not have this structure.

  According to the sixth aspect of the present invention, there is provided a process cartridge using a developer for developing an electrostatic charge image in which generation of fog in an initial output image is suppressed after being left for a long time under high temperature and high humidity. The

  According to the seventh aspect of the present invention, there is provided an image forming apparatus using a developer for developing an electrostatic charge image in which generation of fog in an initial output image is suppressed after being left for a long time under high temperature and high humidity. Is done.

  According to the eighth aspect of the present invention, there is provided an image forming method using a developer for developing an electrostatic charge image in which generation of fog in an initial output image is suppressed after being left for a long time under high temperature and high humidity. Is done.

1 is a schematic configuration diagram illustrating an example of an image forming apparatus according to an exemplary embodiment. It is a schematic block diagram which shows an example of the process cartridge of this embodiment.

  Hereinafter, embodiments of an electrostatic charge image developing developer, a process cartridge, an image forming apparatus, and an image forming method according to the present invention will be described in detail.

<Developer for developing electrostatic image>
The developer for developing an electrostatic charge image according to this embodiment (hereinafter sometimes referred to as the developer of this embodiment) is a developer including a carrier and a toner, and the concentration of the toner with respect to the developer is high. A developer having a relative dielectric constant ε ′ of 12 to 22 and tan δ of 0.01 to 0.07 at 8% by mass.

  Generally, when the image forming apparatus is not used for a long time in a high temperature and high humidity environment, the charge amount of the developer may be significantly reduced. When the image output operation is started with the developer charge amount lowered, problems such as fogging may occur due to low toner charge. For this reason, it is necessary to perform the printing after the developer is idled before printing and the developer is sufficiently charged.

Further, a color image forming apparatus is often composed of four colors of yellow, magenta, cyan, and black. Further, in printing, black single printing is often performed over a long period of time. At this time, if the yellow developing unit, magenta developing unit, and cyan developing unit are at rest, yellow toner, magenta toner, and cyan toner (hereinafter, these may be collectively referred to as color toners) in a high temperature and high humidity environment. The charge amount of the toner decreases, and fogging may occur if a color image is formed in this state. For this reason, when performing color image printing after performing black single printing for a long period of time, it is necessary to rotate the yellow developing device, magenta developing device, and cyan developing device before printing and increase the charge amount before printing.
On the contrary, when the yellow developer, the magenta developer, and the cyan developer are rotated in black single printing, the charging of the color toner does not decrease, but the charge amount may increase with time. In this case, since the charge amount of the color toner is high, the image output parameters (development voltage, transfer voltage, etc.) are set according to the high charge amount for such printing. Thereafter, when the image forming apparatus is left in a high-temperature and high-humidity environment, the amount of charge of the color toner before being left is increased, and the amount of decrease in the charge amount of the color toner after being left is increased. In this case, if image output is performed without idling the developing device, the image forming apparatus may be set as an image output parameter for highly charged toner, and color toner fogging may be severe.

  In view of such a situation, in the present embodiment, in a so-called two-component developer including a carrier and a toner, when the toner concentration is 8% by mass, the relative dielectric constant ε ′ is 12 or more and 22 or less, and tan δ is 0. .01 or more and 0.07 or less. The operation and function when the relative dielectric constant and tan δ of the developer are set to specific ranges will be inferred below.

When the developer of this embodiment is used, a good output image can be obtained even if the developer is left idle (ie, the toner has a high charge amount) under high temperature and high humidity. . This is considered as follows.
When the relative permittivity of the developer is within the range of the present embodiment, the charge amount is appropriate, and the charge movement becomes small as the external environment changes. Further, the polarization of the developer constituting material is suitable, and high charge can be obtained even under high temperature and high humidity. If the relative dielectric constant is less than 12, the developer is less charged and fogging is likely to occur. When the relative dielectric constant exceeds 22, the increase in charging due to turning is strong, and thus fogging after standing is likely to occur.
Further, when tan δ is within the range of the present embodiment, the charge is difficult to escape, so that the charging speed is increased. Therefore, high charge can be obtained early. If tan δ is less than 0.01, fogging is likely to occur due to early charge leakage. If tan δ exceeds 0.07, the electric charge tends to accumulate and the charge recovery is slow, so fogging after standing tends to occur.
By combining the relative permittivity and tan δ within this range, the charge amount and charge attenuation can be made suitable, and the occurrence of fogging in the initial output image (particularly the first print) after being left for a long time is suppressed. Inferred.

In this embodiment, the dielectric properties of the developer are measured as follows.
The developer to be measured is compression molded so as to have a thickness of 5 mm. The compression molding condition is, for example, compression at a pressure of 2.5 MPa / cm ² for 1 minute. Next, relative permittivity and tan δ (relative permittivity loss / relative permittivity) are measured with an LCR meter manufactured by WayneKerr under the conditions of 6 KHz and 5 V (RSM). The measurement environment is 23 ° C. and 55% RH.
In this embodiment, the relative dielectric constant of the developer is preferably 16 or more and 20 or less. The tan δ of the developer is preferably 0.04 or more and 0.06 or less.

  In the present embodiment, the high temperature and high humidity environment refers to an environment of about 30 ° C. and about 88% RH.

  Hereinafter, the toner and carrier constituting the developer according to the exemplary embodiment will be described in detail. The developer of the present embodiment is configured as a two-component developer including a toner and a carrier.

-Toner-
The toner used in this embodiment contains toner particles including a colorant, a binder resin, a release agent, and the like, and an external additive.

  The toner particles used in the present embodiment include a binder resin, but the type of the binder resin is not particularly limited, and a known crystalline resin or amorphous resin may be used. A crystalline resin and an amorphous resin may be used in combination.

Examples of the crystalline resin include crystalline polyester resins, polyalkylene resins, and long-chain alkyl (meth) acrylate resins. However, a sharp change in viscosity due to heating appears more, and mechanical strength and low-temperature fixability From the viewpoint of achieving both, it is desirable to use a crystalline polyester resin.
In addition, since the crystalline polyester resin forms crystals at the linear hydrocarbon portion, the polarizability of that portion is likely to be stable, and the charge amount of the toner is unlikely to decrease under high temperature and high humidity. Furthermore, since the polarization of the linear hydrocarbon portion, which is a crystalline component of the crystalline polyester, is stable with respect to the outside, charging as a developer is not easily affected by the external environment. This is because the dielectric characteristics of the entire developer are difficult to change. Also from these viewpoints, it is desirable to use a crystalline polyester resin.
In the present embodiment, the low temperature fixing means fixing the toner by heating at about 130 ° C. or less.

  Here, the “crystallinity” in the crystalline resin has a clear endothermic peak in the differential scanning calorimetry (DSC), not a stepwise endothermic amount change as shown in JIS K 7121-1987. Specifically, it means that the half-value width of the endothermic peak when measured at a heating rate of 10 (° C./min) is within 10 (° C.). On the other hand, a resin having a half width exceeding 10 ° C. or a resin having no clear endothermic peak means an amorphous resin (amorphous polymer).

  In addition, as the polymerizable monomer component constituting the crystalline resin, a polymerizable monomer having a linear aliphatic component rather than a polymerizable monomer having an aromatic component in order to easily form a crystal structure. The body is desirable. Furthermore, in order not to impair the crystallinity, it is desirable that the constituent component derived from the polymerizable monomer is 30 mol% or more for each single species in the polymer. In particular, when two or more kinds of polymerizable monomers are essential in a polyester resin or the like, it is desirable that each essential constituent polymerizable monomer type has the same configuration.

Hereinafter, the crystalline polyester resin will be mainly described as a representative of the crystalline resin.
The melting temperature of the crystalline polyester resin used in the present embodiment is preferably in the range of 50 ° C. or higher and 100 ° C. or lower, more preferably in the range of 55 ° C. or higher and 90 ° C. or lower, from the storage and low temperature fixability. It is further desirable that the temperature be in the range of 60 ° C or higher and 85 ° C or lower. When the melting temperature is lower than 50 ° C., toner storage properties such as blocking of stored toner and storage properties of fixed images after fixing may become difficult. Further, when the melting temperature exceeds 100 ° C., sufficient low-temperature fixability may not be obtained.
The melting temperature of the crystalline polyester resin was determined as the peak temperature of the endothermic peak obtained by the differential scanning calorimetry (DSC).

  In the present embodiment, the “crystalline polyester resin” includes not only a polymer having a 100% polyester structure as a constituent component but also a polymer (copolymer) obtained by polymerizing a component constituting a polyester and other components. means. However, in the latter case, the component other than the polyester constituting the polymer (copolymer) is 50% by mass or less.

  The crystalline polyester resin used for the toner particles according to this embodiment is synthesized from, for example, a polyvalent carboxylic acid component and a polyhydric alcohol component. In the present embodiment, a commercially available product may be used as the crystalline polyester resin, or a synthesized product 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 Aromatic dicarboxylic acids such as dibasic acids such as, and the like, and anhydrides and lower alkyl esters thereof are also included, but not limited thereto.

  Examples of the trivalent or higher carboxylic acid include specific aromatic carboxylic acids such as 1,2,3-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, and the like. These anhydrides and their lower alkyl esters are exemplified. These may be used individually by 1 type and may use 2 or more types together.

Moreover, as an acid component, the dicarboxylic acid component which has a sulfonic acid group other than the said aliphatic dicarboxylic acid and aromatic dicarboxylic acid may be contained.
Furthermore, in addition to the aliphatic dicarboxylic acid and aromatic dicarboxylic acid, a dicarboxylic acid component having a double bond may be contained.

  As the polyhydric alcohol component, an aliphatic diol is desirable, and a linear aliphatic diol having a main chain portion having 7 to 20 carbon atoms is more desirable. When the aliphatic diol is branched, the crystallinity of the polyester resin is lowered and the melting temperature may be lowered. Further, when the main chain portion has less than 7 carbon atoms, when the polycondensation with the aromatic dicarboxylic acid is performed, the melting temperature becomes high and low temperature fixing may be difficult. On the other hand, when the number of carbons in the main chain portion exceeds 20, it is difficult to obtain practical materials. The number of carbon atoms in the main chain portion is more preferably 14 or less.

  Specific examples of the aliphatic diol suitably used for the synthesis of the crystalline polyester used in the toner particles according to the present embodiment include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 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, considering availability, 1,8-octanediol, 1,9-nonanediol, and 1,10-decanediol are desirable.

  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 polyhydric alcohol components, the content of the aliphatic diol is desirably 80 mol% or more, and more desirably 90 mol% or more. When the content of the aliphatic diol is less than 80 mol%, the crystallinity of the polyester resin is lowered and the melting temperature is lowered, so that toner blocking resistance, image storage stability, and low-temperature fixability may be deteriorated. .

  If necessary, a polycarboxylic acid or a polyhydric alcohol may be added at the final stage of the synthesis for the purpose of adjusting the acid value or the hydroxyl value. Examples of polycarboxylic acids include aromatic carboxylic acids such as terephthalic acid, isophthalic acid, phthalic anhydride, trimellitic anhydride, pyromellitic acid, naphthalenedicarboxylic acid; maleic anhydride, fumaric acid, succinic acid, alkenyl Aliphatic carboxylic acids such as succinic anhydride and adipic acid; alicyclic carboxylic acids such as cyclohexanedicarboxylic acid; 1,2,4-benzenetricarboxylic acid, 1,2,5-benzenetricarboxylic acid, 1,2,4- Examples thereof include aromatic carboxylic acids having at least three carboxyl groups in one molecule such as naphthalene tricarboxylic acid.

  Examples of polyhydric alcohols include aliphatic diols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butanediol, hexanediol, neopentyl glycol, glycerin; cyclohexanediol, cyclohexanedimethanol, hydrogenated bisphenol A, etc. And aromatic diols such as bisphenol A ethylene oxide adduct and bisphenol A propylene oxide adduct.

The production of the crystalline polyester resin can be carried out at a polymerization temperature of 180 ° C. or higher and 230 ° C. or lower. If necessary, the reaction system is reduced in pressure and reacted while removing water and alcohol generated during condensation. .
When the polymerizable monomer is not dissolved or compatible at the reaction temperature, a solvent having a high boiling point may be added as a solubilizing solvent and dissolved. In the polycondensation reaction, the dissolution auxiliary solvent is distilled off. If there is a polymerizable monomer having poor compatibility in the copolymerization reaction, the polymerizable monomer having poor compatibility and the polymerizable monomer and the acid or alcohol to be polycondensed are condensed in advance. And then polycondensation with the main component.

  Catalysts that may be used in the production of the polyester resin include alkali metal compounds such as sodium and lithium; alkaline earth metal compounds such as magnesium and calcium; zinc, manganese, antimony, titanium, tin, zirconium, germanium Metal compounds such as: phosphorous acid compounds; phosphoric acid compounds; and amine compounds.

  Specifically, sodium acetate, sodium carbonate, lithium acetate, lithium carbonate, calcium acetate, calcium stearate, magnesium acetate, zinc acetate, zinc stearate, zinc naphthenate, zinc chloride, manganese acetate, manganese naphthenate, titanium tetraethoxy , Titanium tetrapropoxide, titanium tetraisopropoxide, titanium tetrabutoxide, antimony trioxide, triphenylantimony, tributylantimony, tin formate, tin oxalate, tetraphenyltin, dibutyltin dichloride, dibutyltin oxide, diphenyltin oxide, zirconium tetra Butoxide, Zirconium naphthenate, Zirconyl carbonate, Zirconyl acetate, Zirconyl stearate, Zirconyl octylate, Germanium oxide, Trif Alkenyl phosphite, tris (2,4-di -t- butyl-phenyl) phosphite, ethyltriphenylphosphonium bromide, triethylamine, compounds such as triphenyl amine.

  The acid value of the crystalline polyester resin used in the present embodiment (the number of mg of KOH required to neutralize 1 g of resin) is preferably in the range of 3.0 mgKOH / g to 30.0 mgKOH / g, It is more preferably in the range of 6.0 mgKOH / g or more and 25.0 mgKOH / g or less, and further preferably in the range of 8.0 mgKOH / g or more and 20.0 mgKOH / g or less. In the present embodiment, the acid value is measured according to JIS K-0070-1992.

  When the acid value is lower than 3.0 mgKOH / g, the dispersibility in water is lowered, and thus it may be very difficult to produce emulsified particles by a wet process. Further, since stability as emulsified particles during aggregation is significantly reduced, it may be difficult to produce an efficient toner. On the other hand, when the acid value exceeds 30.0 mgKOH / g, the hygroscopicity as a toner increases and the toner may be easily affected by the environment.

  The crystalline polyester resin preferably has a weight average molecular weight (Mw) of 6,000 or more and 35,000 or less. When the molecular weight (Mw) is less than 6,000, the toner may permeate the surface of a recording medium such as paper at the time of fixing to cause fixing unevenness, or the strength of the fixed image against bending resistance may be reduced. On the other hand, when the weight average molecular weight (Mw) exceeds 35,000, the viscosity at the time of melting becomes too high, and the temperature for reaching a viscosity suitable for fixing may be increased, resulting in the deterioration of the low-temperature fixability. There is a case.

  The weight average molecular weight is measured by gel permeation chromatography (GPC). The molecular weight measurement by GPC was performed with a THF solvent using a Tosoh column / TSKgel Super HM-M (15 cm) using a Tosoh GPC / HLC-8120 as a measuring device. The weight average molecular weight and the number average molecular weight are calculated using a molecular weight calibration curve prepared from a monodisperse polystyrene standard sample from this measurement result.

  The content of the crystalline resin in the toner particles is preferably in the range of 3% by mass to 40% by mass, more preferably in the range of 4% by mass to 35% by mass, and further preferably in the range of 5% by mass or more. The range is 30% by mass or less.

  The crystalline resin containing the above crystalline polyester resin is mainly composed of a crystalline polyester resin synthesized from an aliphatic polymerizable monomer (hereinafter sometimes referred to as “crystalline aliphatic polyester resin”). 50 mass% or more) is desirable. Furthermore, in this case, the constituent ratio of the aliphatic polymerizable monomer constituting the crystalline aliphatic polyester resin is preferably 60 mol% or more, and more preferably 90 mol% or more. As the aliphatic polymerizable monomer, the above-mentioned aliphatic diols and dicarboxylic acids are preferably used.

  As the amorphous resin in the present embodiment, known resin materials such as styrene / acrylic resin, epoxy resin, polyester resin, polyurethane resin, polyamide resin, cellulose resin, polyether resin, polyolefin resin may be used. Amorphous polyester resins are particularly desirable.

  By using an amorphous polyester resin, the compatibility with the crystalline polyester resin is improved, so that the amorphous polyester resin is also reduced in viscosity as the melting temperature of the crystalline polyester resin is lowered, and as a toner Therefore, it is advantageous for low temperature fixability. In addition, since the wettability with the crystalline polyester resin is good, the dispersibility of the crystalline polyester resin inside the toner is improved, and the exposure of the crystalline polyester resin to the toner surface is suppressed. Is suppressed. For this reason, it is also desirable from the viewpoint of improving the strength of the toner and the strength of the fixed image.

Hereinafter, the amorphous resin in the present embodiment will be described by focusing on the amorphous polyester resin.
The amorphous polyester resin desirably used in the present embodiment is obtained, for example, by condensation polymerization of polyvalent carboxylic acids and polyhydric alcohols.
Examples of polycarboxylic acids include aromatic carboxylic acids such as terephthalic acid, isophthalic acid, phthalic anhydride, trimellitic anhydride, pyromellitic acid, naphthalenedicarboxylic acid; maleic anhydride, fumaric acid, succinic acid, alkenyl Aliphatic carboxylic acids such as succinic anhydride and adipic acid; alicyclic carboxylic acids such as cyclohexanedicarboxylic acid, and the like. These polyvalent carboxylic acids may be used alone or in combination. Among these polyvalent carboxylic acids, it is desirable to use aromatic carboxylic acids, and in order to ensure good fixability, it is desirable to have a crosslinked structure or a branched structure. It is desirable to use carboxylic acid (trimellitic acid or its acid anhydride) in combination.

  Examples of the polyhydric alcohol in the amorphous polyester resin include aliphatic diols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butanediol, hexanediol, neopentylglycol, glycerin, etc .; cyclohexanediol, cyclohexane Examples thereof include alicyclic diols such as dimethanol and hydrogenated bisphenol A; aromatic diols such as an ethylene oxide adduct of bisphenol A and a propylene oxide adduct of bisphenol A. One or more of these polyhydric alcohols may be used. Among these polyhydric alcohols, aromatic diols and alicyclic diols are desirable, and among these, aromatic diols are more desirable. In order to secure better fixing properties, it is desirable to have a cross-linked structure or a branched structure. For this purpose, a trihydric or higher polyhydric alcohol (glycerin, trimethylolpropane, pentaerythritol) may be used in combination with the diol. Good.

  In this embodiment, it is desirable to contain alkenyl succinic acid or its anhydride as a constituent component of the amorphous polyester resin. By using an amorphous polyester resin containing alkenyl succinic acid or an anhydride thereof as a constituent component, compatibility with the crystalline resin is improved and good low-temperature fixability is obtained. Examples of alkenyl succinic acid include dodecenyl succinic acid and octyl succinic acid.

The glass transition temperature (Tg) of the amorphous polyester resin is desirably in the range of 50 ° C to 80 ° C. If Tg is lower than 50 ° C., problems may occur in terms of toner storage stability and fixed image storage stability. On the other hand, if the temperature is higher than 80 ° C., it may not be possible to fix at a lower temperature than in the past.
The Tg of the amorphous polyester resin is more preferably 50 ° C. or higher and 65 ° C. or lower.
The glass transition temperature of the amorphous polyester resin was determined as the peak temperature of the endothermic peak obtained by the differential scanning calorimetry (DSC).

  The content of the amorphous resin in the toner particles is preferably in the range of 40% by mass to 95% by mass, more preferably in the range of 50% by mass to 90% by mass, and still more preferably 60% by mass. It is the range below 85 mass%.

In addition, you may perform manufacture of the said amorphous polyester resin according to the case of the said crystalline polyester resin.
As described above, the crystalline resin and the amorphous resin in the present embodiment have been described using the crystalline polyester resin and the amorphous polyester resin. However, the contents other than the production of the polyester resin are the other crystalline properties in the present embodiment. You may apply about resin and an amorphous resin.

The weight average molecular weight (Mw) of the amorphous polyester resin is desirably 30,000 or more and 300,000 or less. When the molecular weight (Mw) is 30,000 or more and 300,000 or less, the shape of the toner is controlled, and the shape can be easily controlled. Furthermore, high temperature offset resistance is obtained.
The weight average molecular weight (Mw) of the amorphous polyester resin is more preferably from 30,000 to 200,000, and particularly preferably from 35,000 to 150,000.

  In the present embodiment, it is desirable to use a crystalline polyester resin and an amorphous polyester resin in combination as the binder resin.

  Other binder resins other than the above-mentioned binder resins include styrenes such as styrene and chlorostyrene, monoolefins such as ethylene, propylene, butylene, and isoprene, vinyl acetate, vinyl propionate, vinyl benzoate, and vinyl butyrate. Α-methylene such as methyl acrylate, methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, dodecyl methacrylate, etc. Homopolymers such as aliphatic monocarboxylic acid esters, vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, vinyl butyl ether, vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, vinyl isopropenyl ketone, and Examples of the polymer include polystyrene, styrene-alkyl acrylate copolymer, styrene-alkyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyethylene. Polypropylene or the like may be used. Further, polyurethane, epoxy resin, silicone resin, polyamide, modified rosin, paraffin wax and the like can be mentioned.

The toner particles according to this embodiment may include a colorant. The colorant used in this embodiment may be a dye or a pigment, but a pigment is desirable from the viewpoint of light resistance and water resistance.
Desirable colorants include carbon black, aniline black, aniline blue, calcoil blue, chrome yellow, ultramarine blue, dupont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green oxalate, lamp black, rose bengal Quinacridone, benzicine yellow, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 185, C.I. I. Pigment red 238, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 180, C.I. I. Pigment yellow 97, C.I. I. Pigment yellow 74, C.I. I. Pigment blue 15: 1, C.I. I. A known pigment such as CI Pigment Blue 15: 3 may be used.

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

The toner particles used in this embodiment may include inorganic particles.
The inorganic particles are added for various purposes, but may be added for adjusting the viscoelasticity of the toner. By adjusting the viscoelasticity, image glossiness and penetration into paper are adjusted. As the inorganic particles, known inorganic particles such as silica particles, titanium oxide particles, alumina particles, cerium oxide particles, or those obtained by hydrophobizing the surface thereof may be used alone or in combination of two or more. From the viewpoint of not impairing transparency such as color developability and OHP permeability, silica particles having a refractive index smaller than that of the binder resin are desirable. Further, the silica particles may be subjected to various surface treatments, and for example, those treated with a silane coupling agent, a titanium coupling agent, a silicone oil, or the like may be used.

In addition to the above components, various components such as a release agent, an internal additive, a charge control agent, and organic particles may be further added to the toner particles used in the exemplary embodiment as necessary.
Examples of the internal additive include metals such as ferrite, magnetite, reduced iron, cobalt, nickel, and manganese, alloys, and magnetic materials such as compounds containing these metals.

  Examples of the release agent include paraffin wax such as low molecular weight polypropylene and low molecular weight polyethylene; silicone resin; rosins; rice wax; carnauba wax; The melting temperature of these release agents is preferably 50 ° C. or higher and 100 ° C. or lower, and more preferably 60 ° C. or higher and 95 ° C. or lower. The content of the release agent in the toner is desirably 0.5% by mass or more and 15% by mass or less, and more desirably 1.0% by mass or more and 12% by mass or less. If the content of the release agent is less than 0.5% by mass, there is a risk of peeling failure particularly in oilless fixing. When the content of the release agent is more than 15% by mass, the fluidity of the toner is deteriorated and the image quality and the reliability of image formation may be deteriorated.

  Known charge control agents may be used, but azo metal complex compounds, metal complex compounds of salicylic acid, and resin type charge control agents containing polar groups may be used.

The toner used in this embodiment may contain an external additive.
Examples of the external additive include silica, alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, silica sand, clay, mica, wollastonite, diatomaceous earth, and chloride. Examples include cerium, bengara, chromium oxide, cerium oxide, antimony trioxide, magnesium oxide, zirconium oxide, silicon carbide, and silicon nitride. Among these, silica particles and / or titania particles are desirable, and silica particles and titania particles subjected to hydrophobic treatment are particularly desirable.

The external additive is generally used for the purpose of improving the fluidity of the toner. Among external additives, by using TiO (OH) ₂ metatitanate, excellent transparency, good chargeability, environmental stability, fluidity, caking resistance, stable negative chargeability, stable image quality maintainability Is obtained. In addition, the hydrophobized compound of metatitanic acid has an electric resistance of 10 ¹⁰ Ω · cm or more, so that even if the transfer electric field is increased, high transferability can be obtained without generating a reversely charged toner. desirable. The volume average particle size of the external additive for the purpose of imparting fluidity is preferably in the range of 1 nm to 40 nm in terms of the primary particle size, and more preferably in the range of 5 nm to 20 nm. The volume average particle size of the external additive for the purpose of improving transferability is desirably 50 nm or more and 500 nm or less. These external additive particles are preferably subjected to surface modification such as hydrophobization in order to stabilize the chargeability and developability.

  A conventionally known method is used as the means for surface modification. Specific examples include coupling treatments such as silane, titanate, and aluminate. The coupling agent used for the coupling treatment is not particularly limited. For example, methyltrimethoxysilane, phenyltrimethoxysilane, methylphenyldimethoxysilane, diphenyldimethoxysilane, vinyltrimethoxysilane, γ-aminopropyltrimethoxysilane , Γ-chloropropyltrimethoxysilane, γ-bromopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-ureidopropyltrimethoxysilane, fluoroalkyltrimethoxysilane, hexa Silane coupling agents such as methyldisilazane; titanate coupling agents; aluminate coupling agents;

  Furthermore, various additives may be added as necessary. Examples of these additives include other fluidizing agents, cleaning aids such as polystyrene particles, polymethyl methacrylate particles, and polyvinylidene fluoride particles, and zinc stearyl. Examples thereof include abrasives for the purpose of removing adhering substances such as amide and strontium titanate.

  The addition amount of the external additive is preferably in the range of 0.1 to 5 parts by mass, more preferably in the range of 0.3 to 2 parts by mass with respect to 100 parts by mass of the toner particles. When the addition amount is less than 0.1 parts by mass, the fluidity of the toner may be deteriorated, and there may be problems such as deterioration of chargeability and charge exchange property, which may be unfavorable. On the other hand, when the added amount is more than 5 parts by mass, an excessive covering state is caused, and the excessive inorganic oxide may be transferred to the contact member to cause a secondary failure.

  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, an emulsion aggregation method that can easily produce a toner having a core-shell structure is desirable. Hereinafter, a method for producing a toner by the emulsion aggregation method will be described in detail.

In the emulsification aggregation method in this embodiment, the aggregation resin is formed by adding an aggregating agent to a mixed dispersion obtained by mixing at least a binder resin particle dispersion in which binder resin particles are dispersed and a colorant dispersion in which a colorant is dispersed. An agglomerated particle forming step, and the binder resin particle dispersion is further added to the mixed dispersion in which the agglomerated particles are formed, and the binder resin particles are adhered to the surface of the agglomerated particles to agglomerate the resin. You may have the adhesion process which forms particle | grains, and the fusion process which fuse | melts the said resin adhesion aggregation particle | grains by heating.
Since the toner particles produced through the above steps are covered with a shell layer composed of a binder resin, the colorant contained in the toner particles, the release agent used as necessary, etc. It is hard to be exposed to. For this reason, a toner containing toner particles produced through emulsion aggregation is preferable for suppressing fog because the charge is unlikely to decrease.

(Emulsification process)
For example, the binder resin particle dispersion may be produced by applying a shearing force to a solution obtained by mixing an aqueous medium and a binder resin with a disperser. At that time, particles may be formed by heating to lower the viscosity of the binder resin component. Further, a dispersant may be used for stabilizing the dispersed binder resin particles. Furthermore, if the binder 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 water together with a dispersant and a polymer electrolyte, and then heated or heated. A binder resin particle dispersion is 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.
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 producing the binder resin particle dispersion 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 1.0 μm or less, more preferably in the range of 60 nm to 300 nm, and even more preferably in the range of 150 nm to 250 nm. . If it is less than 60 nm, the resin particles become stable particles in the dispersion, and thus aggregation of the resin particles may be difficult. If it exceeds 1.0 μm, the cohesiveness of the resin particles is improved and it becomes easy to prepare toner particles, but the particle size distribution of the toner may be widened.

  In preparing the release agent dispersion, the release agent is dispersed in water together with an ionic surfactant, a polymer electrolyte such as 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 to which a strong shearing force is applied while heating. By undergoing such treatment, a release agent dispersion is obtained. During the dispersion treatment, an inorganic compound such as polyaluminum chloride may be added to the dispersion. Examples of desirable inorganic compounds include polyaluminum chloride, aluminum sulfate, highly basic polyaluminum chloride (BAC), polyaluminum hydroxide, and aluminum chloride. Among these, polyaluminum chloride and aluminum sulfate are desirable. The release agent dispersion is used in the emulsion aggregation method, but the release agent dispersion may also be used when the toner is produced by suspension polymerization.

By the dispersion treatment, a release agent dispersion liquid containing release agent particles having a volume average particle diameter of 1 μm or less is obtained. The more desirable volume average particle size of the release agent particles is 100 nm or more and 500 nm or less.
When the volume average particle size is less than 100 nm, the properties of the binder resin to be used are affected, but generally the release agent component is hardly taken into the toner. On the other hand, if it exceeds 500 nm, the dispersion state of the release agent in the toner may be insufficient.

  For the preparation of the colorant dispersion, a known dispersion method can be used. For example, a general dispersion means such as a rotary shear type homogenizer, a ball mill having a medium, a sand mill, a dyno mill, or an optimizer can be employed. Is not to be done. The colorant is dispersed in water together with a polymer electrolyte such as an ionic surfactant, a polymer acid, or a polymer base. The volume average particle diameter of the dispersed colorant particles may be 1 μm or less, but if it is in the range of 80 nm or more and 500 nm or less, the dispersion of the colorant in the toner is preferable without impairing the cohesiveness.

(Aggregated particle forming step)
In the aggregated particle forming step, a binder resin particle dispersion, a colorant dispersion, a release agent dispersion, and the like are mixed to form a mixed dispersion, and an aggregate is added to aggregate to form aggregated particles. In this case, the mixed dispersion may be heated at a temperature not higher than the glass transition temperature of the binder resin particles. Aggregated particles are often formed by making the pH of the mixed solution acidic under stirring. The pH is preferably in the range of 2 to 7.
In the agglomerated particle forming step, the release agent dispersion may be added and mixed at the same time with various dispersions such as a binder 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 divalent or higher-valent metal complex are preferably used. In particular, the use of a metal complex is particularly desirable because the amount of the surfactant used can be reduced and the charging characteristics are improved.

As the inorganic metal salt, an aluminum salt and a polymer thereof are particularly suitable. In order to obtain a narrower particle size distribution, the valence of the inorganic metal salt is bivalent than monovalent, trivalent than bivalent, trivalent than trivalent, and tetravalent than trivalent. Inorganic metal salt polymers are more suitable.
In this embodiment, it is desirable to use a polymer of a tetravalent inorganic metal salt containing aluminum in order to obtain a narrow particle size distribution.

(Adhesion process)
In the attaching step, a coating layer is formed by attaching the binder resin particles to the surface of the aggregated particles formed through the above-described aggregated particle forming step (the aggregated particles provided with the coating layer on the surface of the aggregated particles are “resin” Sometimes referred to as "adhesive aggregated particles"). Here, this coating layer corresponds to a shell layer formed through a fusion process described later.

  The coating layer may be formed by further adding the binder resin particle dispersion to the mixed dispersion in which the aggregated particles are formed in the aggregated particle forming step. In the attaching step, other components such as an aggregating agent may be additionally added as necessary.

  There is no restriction | limiting in particular as the addition mixing method of the binder resin particle dispersion in an adhesion | attachment process, For example, you may carry out gradually continuously and may carry out in steps divided into several times. Thus, by adding and mixing the binder resin particle dispersion, the generation of fine particles is suppressed, and the particle size distribution of the obtained toner particles becomes sharp.

  In the present embodiment, the number of times that this adhesion step is performed may be one or a plurality of times. Multiple layers of shells may be made by changing the resin.

  Conditions for attaching the binder resin particles to the aggregated particles are as follows. That is, the heating temperature in the attaching step may be a temperature range from the glass transition temperature of the binder resin contained in the aggregated particles to the glass transition temperature of the binder resin for the shell layer.

The heating time in the adhesion step depends on the heating temperature and cannot be defined generally, but is usually 5 minutes or more and 2 hours or less.
In addition, in the attaching step, after the binder resin particle dispersion is additionally added to the mixed dispersion in which the aggregated particles are formed, it may be allowed to stand or may be gently stirred by a mixer or the like. . The latter case is advantageous in that uniform resin-adhesive aggregated particles are easily formed.

  In the adhesion step, the amount of the binder resin particle dispersion used depends on the particle size of the binder resin particles contained therein, but the thickness of the finally formed shell layer is about 20 nm to 500 nm. It is desirable to be selected so that

(Fusion process)
In the fusing step, under the stirring conditions according to the agglomerated particle forming step, the pH of the suspension of the resin-adhered agglomerated particles is raised to a range of 3 to 9 to stop the agglomeration, and the binder resin The resin-adhered aggregated particles are fused by heating at a temperature equal to or higher than the glass transition temperature. The heating time may be performed to the extent that fusion is performed, and may be performed for about 0.5 hour to 10 hours.

Cool after fusion to obtain fused particles. Further, in the cooling step, crystallization may be promoted by reducing the cooling rate in the vicinity of the glass transition temperature (range of glass transition temperature ± 10 ° C.) of the resin, so-called slow cooling.
The fused particles obtained by fusing are made into toner particles through a solid-liquid separation process such as filtration and, if necessary, a washing process and a drying process.

  As an external addition method of the external additive to the toner particles, there is a method in which the external additive is added to the toner particles and mixed by a known mixer such as a V-type blender, a Henschel mixer, or a Redige mixer.

(Toner characteristics)
The toner used in the present exemplary embodiment is preferably spherical with a shape factor SF1 in the range of 115 to 140.
As for the shape of the toner, the spherical toner is advantageous in terms of developability and transferability, but may be inferior to the indeterminate shape in terms of cleaning properties. When the toner has a shape in the above range, the transfer efficiency and image density are improved, high-quality image formation is performed, and the cleaning property of the surface of the photoreceptor is enhanced.
The shape factor SF1 is more preferably in the range of 120 to 138.

Here, the shape factor SF1 is obtained by the following equation (3).
SF1 = (ML ² / B) × (π / 4) × 100 (3)
In the above formula (3), ML represents the absolute maximum length of the toner particles, and B represents the projected area of the toner particles.

  SF1 is quantified mainly by analyzing a microscope image or a scanning electron microscope (SEM) image using an image analyzer, and is 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, and the maximum length and projected area of 100 particles are obtained, calculated by the above equation (3), and the average value is calculated. It is obtained by seeking.

  Further, the volume average particle size of the toner used in the exemplary embodiment is desirably 3 μm or more and 9 μm or less, more desirably 3.5 μm or more and 8.5 μm or less, and further desirably 4 μm or more and 8 μm or less. If the volume average particle diameter is 3 μm or more, a decrease in toner fluidity can be suppressed, and the chargeability of each particle can be easily maintained. In addition, the charge distribution does not spread, preventing fogging on the background and preventing toner from spilling from the developer. Further, when the volume average particle diameter of the toner is 3 μm or more, the cleaning property is improved. If the volume average particle size is 9 μm or less, a decrease in resolution can be suppressed, so that a sufficient image quality can be obtained and the recent demand for higher image quality is satisfied.

  The volume average particle diameter D50 is measured by a measuring instrument such as Coulter Multisizer II (manufactured by Coulter, Inc.).

-Career-
The developer of this embodiment contains a carrier. The carrier that can be used in the developer of the present embodiment is not particularly limited, and a known carrier is used. Examples thereof include magnetic metals such as iron oxide, nickel and cobalt, magnetic oxides such as ferrite and magnetite, resin-coated carriers having a resin coating layer on the surface of these core materials, and magnetic dispersion carriers. Further, a resin-dispersed carrier in which a conductive material or the like is dispersed in a matrix resin may be used.

  The carrier used in the present embodiment may be a resin-coated carrier having a magnetic core material and a resin coating layer that covers the magnetic core material.

The magnetic core material used in the present embodiment is not particularly limited, and a magnetic metal such as iron, steel, nickel, cobalt, or a magnetic oxide such as ferrite or magnetite, a magnetic particle including a magnetic particle and a binder resin. Examples include a dispersion type core material.
In the present embodiment, it is desirable that the magnetic core material contains a ferrite represented by the following formula (1). By including the ferrite represented by the formula (1) in the magnetic core material, it is easy to adjust the relative dielectric constant and tan δ of the developer of the present embodiment to a desirable range.

(MO) _X (Fe ₂ O ₃ ) _Y formula (1)
In Formula (1), Y represents 2.1 or more and 2.4 or less, and X represents 3-Y. M represents a metal element, and contains at least Mn as the metal element.

  As M in the formula (1), Mn is mainly used, but at least one selected from the group consisting of Li, Ca, Sr, Sn, Cu, Zn, Ba, Mg, and Ti may be combined. However, it is desirable to select Li, Ca, Sr, Mg, and Ti from the environmental aspect.

When manufacturing the magnetic core material, it is easy to obtain the desired dielectric properties by controlling the amount of Fe and the amounts of Ti, Si, and Sr as additives. This is because the degree of sintering of ferrite is adjusted.
In addition, the relative dielectric constant increases by increasing the amount of Fe with respect to the ferrite composition ratio Fe: M = 2: 1. In Formula (1), Y is preferably 2.1 or more and 2.4 or less, and more preferably 2.2 or more and 2.3 or less.

When manufacturing ferrite, by adding SiO ₂ as an additive, the sintered state of ferrite is manipulated and the relative dielectric constant is controlled. Furthermore, it becomes easy to adjust the ratio of the volume average particle diameter D50 and the BET specific surface area A to a desirable range represented by the following formula (2). Similarly, when producing ferrite, the sintering state is manipulated by adding Ti and Sr as additives.

  Specifically, tan δ is adjusted by increasing the Fe ratio of ferrite and adding a magnetite component appropriately. At the same time, in order to achieve both a BET specific surface area and a dielectric constant, when the amount of Fe is large, the degree of sintering of ferrite is reduced with Si or the like, and when the amount of Fe is small, the sintering of ferrite is promoted with Sr or the like. You may plan.

Addition of SiO ₂ as an additive inhibits the sintering of ferrite. The addition amount of SiO ₂ is desirably in the range of 0.05 mol or more and 0.4 mol with respect to 1 mol of Fe in terms of the molar ratio of Si. If it is less than 0.05 mol, the sintering inhibiting effect is small, and if it exceeds 0.4 mol, the sintering inhibiting effect is too large.
On the other hand, ferrite is promoted by adding Ti and Sr as additives. The addition amount of Ti and Sr is desirably in the range of 0.05 mol or more and 0.4 mol with respect to 1 mol of Fe in terms of the molar ratio of Ti and Sr. If it is less than 0.05 mol, the sintering promoting effect is small, and if it exceeds 0.4 mol, the sintering promoting effect is too large.

In the present embodiment, the composition of ferrite contained in the magnetic core material and the content of Si, Sr or Ti with respect to 1 mol of Fe contained in the magnetic core material are determined by the following method.
A constituent element can be specified by fluorescent X-rays. The content is measured from a quantitative analysis using a calibration curve. The number of moles can be obtained by dividing the obtained content by the atomic weight, and the molar ratio with respect to each Fe can be obtained from the ratio.

In the present embodiment, it is desirable that the volume average particle diameter D50 (μm) and the BET specific surface area A (m ² / g) of the magnetic core material satisfy the following formula (2).
0.003 ≦ A / D50 ≦ 0.011 Formula (2)

When the magnetic core material satisfies the range of the formula (2), the magnetic core material is easily exposed moderately, so that the influence of the relative dielectric constant of the magnetic core material on the developer of the present embodiment is increased. Since ferrite is a crystal, charging speed by ionic polarization is fast, and charging is stabilized earlier.
When the A / D50 is less than 0.003, the exposure of the magnetic core material is reduced and the charge amount is increased, but the charging speed is slow, and the charge recovery after being left may be slow. When A / D50 exceeds 0.011, the magnetic core material is exposed more and the charging speed is faster, but the charge amount may decrease.

  In the present embodiment, the BET specific surface area of the magnetic particles refers to a value measured by a nitrogen substitution method. Specifically, the measurement was performed by a three-point method using an SA3100 specific surface area measuring device (manufactured by Beckman Coulter, Inc.). As a magnetic particle sample, 5 g is put into a cell, subjected to a degassing treatment at 60 ° C. for 120 minutes, and measured using a mixed gas of nitrogen and helium (30:70).

The volume average particle diameter of the magnetic particles is measured as follows.
The particle size of 100 particles is measured from the SEM photograph of magnetic particles, and the 50th particle size is defined as the volume average particle size.

The ratio between the volume average particle diameter of the magnetic particles and the BET specific surface area is adjusted as follows.
An appropriate amount of each material constituting the magnetic particles is blended, pulverized and mixed with a wet ball mill, and granulated and dried with a spray dryer or the like. Next, temporary baking is performed in a rotary kiln or the like. Furthermore, it grind | pulverizes with a wet ball mill. At this time, the final particle size and the BET specific surface area are controlled by controlling the pulverized particle size. If this pulverized particle size is reduced, the BET tends to be increased. Also, the particle size is easy to reduce. Subsequently, this slurry is similarly granulated and dried with a spray drier or the like to produce particles before firing. The final particle size is determined by the particle size at this time. Next, firing is performed, and the final BET specific surface area is adjusted by controlling the temperature condition. Further, the preliminary baking may be repeated a plurality of times to control the BET specific surface area and the particle size.
These manufacturing conditions differ depending on the additive material. Therefore, target ferrite particles are produced by a combination of the composition of the additive material and the manufacturing conditions.

  For example, an appropriate amount of each oxide is first blended, pulverized and mixed for 8 hours to 35 hours with a wet ball mill or the like, granulated and dried with a spray dryer or the like, and then heated at 800 ° C. to 1000 ° C. with a rotary kiln or the like. Temporary baking is performed for not less than 10 hours. Temporary baking is performed once or more and three times or less as necessary. Thereafter, the calcined product is dispersed in water and pulverized with a wet ball mill or the like until the volume average particle size becomes 0.3 μm or more and 2.0 μm or less. This slurry is granulated and dried using a spray drier, etc., and for the purpose of adjusting magnetic properties and resistance, the main calcination is performed at 1000 ° C. or higher and 1300 ° C. or lower for 6 hours or longer and 10 hours or less while controlling the oxygen concentration, and then pulverized. Further, magnetic particles may be obtained by classification into a desired particle size distribution.

  In the present embodiment, the resin constituting the resin coating layer is not particularly limited as long as it is used as a matrix resin, and is selected according to the purpose. For example, polyolefin resins such as polyethylene and polypropylene; polyvinyl resins and polyvinylidene resins such as polystyrene, acrylic resins, polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl carbazole, polyvinyl ether and polyvinyl ketone 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, polychlorotrifluoroethylene, etc. Fluorine resin; Silicone resin; Polyester; Polyurethane; Polycarbonate; Phenol resin; Urea-formaldehyde resin, Melamine tree , Benzoguanamine resins, urea resins, amino resins such as polyamide resins, epoxy resins, per se known resins and the like. These may be used individually by 1 type and may use 2 or more types together.

The resin coating layer covering the magnetic core material may contain conductive particles in the resin. Here, the conductivity means that the volume resistivity is less than 10 ⁷ Ω · cm.
Specific examples of the conductive particles include metal oxides such as carbon black, various metal powders, titanium oxide, tin oxide, magnetite, and ferrite. These may be used individually by 1 type and may use 2 or more types together. Among these, carbon black particles are desirable from the viewpoints of production stability, cost, conductivity, and the like. The type of carbon black is not particularly limited, but carbon black having a DBP oil absorption of about 50 ml / 100 g or more and 250 ml / 100 g or less is desirable because of its excellent production stability.

The method for forming the resin coating layer for coating the magnetic core material is not particularly limited. For example, conductive particles and a resin such as a styrene acrylic resin, a fluorine resin, or a silicone resin as a coating resin in a solvent. And the like using a film forming solution contained in the above.
Specifically, an immersion method in which the magnetic core material is immersed in the film forming liquid, a spray method in which the film forming liquid is sprayed on the surface of the magnetic core material, and the film in a state where the magnetic core material is suspended by flowing air. For example, a kneader coating method in which the forming liquid is mixed and the solvent is removed. Among these, in the present embodiment, the solution in which the coating resin is dissolved is stirred and dispersed using a disperser such as UltraTurrax T50, and the coating film forming solution and the magnetic core material are mixed in a kneader coater. Then, a kneader coating method for removing the solvent is desirable.

  The solvent used for the film forming liquid is not particularly limited as long as it dissolves the resin as a matrix resin, and can be selected from known solvents such as toluene and xylene. Aromatic hydrocarbons, ketones such as acetone and methyl ethyl ketone, ethers such as tetrahydrofuran and dioxane, and the like.

  The carrier used in this embodiment may have a volume average particle size of 30 μm or more and 90 μm or less, or 40 μm or more and 80 μm or less. If the volume average particle size is less than 30 μm, the carrier may easily adhere to the photoconductor, and if it exceeds 90 μm, the image quality may deteriorate.

  In this embodiment, the mixing ratio (mass ratio) of the carrier and the toner is preferably in the range of toner: carrier = 1: 100 to 30: 100, and more preferably in the range of 3: 100 to 20: 100.

<Image Forming Apparatus and Image Forming Method>
Next, an image forming apparatus and an image forming method according to this embodiment using the developer of this embodiment will be described.
The image forming apparatus according to the present embodiment includes a latent image holding member, a charging unit that charges the surface of the latent image holding member, an electrostatic charge image forming unit that forms an electrostatic charge image on the surface of the latent image holding member, Developing means for developing an electrostatic image with the developer of the present embodiment to form a toner image, transfer means for transferring the toner image to a recording medium, fixing means for fixing the toner image on the recording medium, Is provided. The image forming apparatus according to the present embodiment may include other means as necessary, for example, a cleaning means for removing the residual transfer component by rubbing the latent image holding member with a cleaning member, and cleaning. Good.

  By using the image forming apparatus according to the present embodiment, a charging step for charging the surface of the latent image holding member, an electrostatic charge image forming step for forming an electrostatic charge image on the surface of the latent image holding member, and the electrostatic charge image A development step of developing with the developer of the present embodiment to form a toner image, a transfer step of transferring the toner image to a recording medium, and a fixing step of fixing the toner image on the recording medium. The image forming method according to the embodiment is performed.

  Hereinafter, an example of the image forming apparatus according to the present embodiment will be described, but the present invention is not limited thereto. The main parts shown in the figure will be described, and the description of the other parts will be omitted.

  In this image forming apparatus, for example, the part including the developing device may have a cartridge structure (process cartridge) that is detachable from the main body of the image forming apparatus. As the process cartridge, a developer holding member is used. A process cartridge according to this embodiment that is provided at least and that accommodates the developer of this embodiment is preferably used.

FIG. 1 is a schematic configuration diagram illustrating a four-tandem color image forming apparatus which is an example of an image forming apparatus according to the present embodiment. A two-component developer is used as the developer.
The image forming apparatus shown in FIG. 1 is a first to first electrophotographic method that outputs yellow (Y), magenta (M), cyan (C), and black (K) images based on color-separated image data. Fourth image forming units 10Y, 10M, 10C, and 10K (image forming means) are provided. These image forming units (hereinafter simply referred to as “units”) 10Y, 10M, 10C, and 10K are juxtaposed at a predetermined distance from each other in the horizontal direction. The units 10Y, 10M, 10C, and 10K may be process cartridges that are detachable from the image forming apparatus.

Above each of the units 10Y, 10M, 10C, and 10K, an intermediate transfer belt 20 as an intermediate transfer member is extended through each unit. The intermediate transfer belt 20 is provided by being wound around a driving roller 22 and a support roller 24 that are in contact with the inner surface of the intermediate transfer belt 20 that are spaced apart from each other from the left to the right in the drawing. It is designed to travel in the direction toward 10K. The support roller 24 is urged away from the drive roller 22 by a spring or the like (not shown), and a predetermined tension is applied to the intermediate transfer belt 20 wound around the support roller 24. An intermediate transfer member cleaning device 30 is provided on the side surface of the latent image holding member of the intermediate transfer belt 20 so as to face the drive roller 22.
Further, each of the developing devices (developing means) 4Y, 4M, 4C, and 4K of the units 10Y, 10M, 10C, and 10K includes yellow, magenta, cyan, and the like housed in the developer cartridges 8Y, 8M, 8C, and 8K. A developer for developing an electrostatic image containing black toner of four colors is supplied.

  Since the first to fourth units 10Y, 10M, 10C, and 10K described above have the same configuration, here, the first unit that forms a yellow image disposed on the upstream side in the intermediate transfer belt traveling direction. 10Y will be described as a representative. Note that the second to fourth units are denoted by reference numerals with magenta (M), cyan (C), and black (K) instead of yellow (Y) in the same parts as the first unit 10Y. Description of 10M, 10C, 10K is omitted.

The first unit 10Y has a latent image holding body 1Y that functions as a photoconductor. Around the latent image holding body 1Y, a charging roller 2Y for charging the surface of the latent image holding body 1Y to a predetermined potential, and the charged surface is exposed by a laser beam 3Y based on the color-separated image signal so as to be static. An exposure device 3 that forms a charge image, a developing device (developing means) 4Y that supplies toner charged to the electrostatic charge image to develop the electrostatic charge image, and a primary transfer that transfers the developed toner image onto the intermediate transfer belt 20 A roller 5Y (primary transfer unit) and a latent image holding member cleaning device (cleaning unit) 6Y for removing toner remaining on the surface of the latent image holding member 1Y after the primary transfer are sequentially arranged.
The primary transfer roller 5Y is disposed inside the intermediate transfer belt 20 and is provided at a position facing the latent image holder 1Y. Further, a bias power source (not shown) for applying a primary transfer bias is connected to each of the primary transfer rollers 5Y, 5M, 5C, and 5K. Each bias power source varies the transfer bias applied to each primary transfer roller under the control of a control unit (not shown).

The image forming apparatus illustrated in FIG. 1 is an image forming apparatus having a configuration in which the developer cartridges 8Y, 8M, 8C, and 8K can be attached and detached. The developing apparatuses 4Y, 4M, 4C, and 4K each have a developing device (color). ) Corresponding to the developer cartridges 8Y, 8M, 8C and 8K. Further, the developing devices 4Y, 4M, 4C, and 4K are connected to a developer discharge pipe (not shown) that discharges the excessively deteriorated developer (including many deteriorated carriers). With such a configuration, a so-called trickle developing system (the developer for replenishment (trickle developer) is gradually supplied into the developing device, while the deteriorated developer that has become excessive (contains many deteriorated carriers) is discharged. Development method for performing development).
When the developer cartridges 8Y, 8M, 8C, and 8K containing the developer for developing the electrostatic charge image are employed, and the amount of developer stored in the developer cartridge decreases, the developer cartridge is replaced. The

Hereinafter, an operation of forming a yellow image in the first unit 10Y will be described. First, prior to the operation, the surface of the latent image holding body 1Y is charged to a potential of about −600V to −800V by the charging roller 2Y.
The latent image holding body 1Y is formed by laminating a photosensitive layer on a conductive (volume resistivity at 20 ° C .: 1 × 10 ⁻⁶ Ωcm or less). This photosensitive layer usually has a high resistance (a resistance equivalent to that of a general resin), but has a property that the specific resistance of the portion irradiated with the laser beam changes when irradiated with the laser beam 3Y. Therefore, a laser beam 3Y is output to the surface of the charged latent image holding body 1Y via the exposure device 3 in accordance with yellow image data sent from a control unit (not shown). The laser beam 3Y is applied to the photosensitive layer on the surface of the latent image holder 1Y, whereby an electrostatic charge image of a yellow print pattern is formed on the surface of the latent image holder 1Y.

The electrostatic charge image is an image formed on the surface of the latent image holding body 1Y by charging, and the specific resistance of the irradiated portion of the photosensitive layer is lowered by the laser beam 3Y, and the surface of the latent image holding body 1Y is charged. On the other hand, this is a so-called negative latent image formed by the remaining charge remaining in the portion not irradiated with the laser beam 3Y.
The electrostatic charge image formed on the latent image holding body 1Y in this way is rotated to a predetermined development position as the latent image holding body 1Y travels. At this development position, the electrostatic charge image on the latent image holding member 1Y is converted into a visible image (toner image) by the developing device 4Y.

  Yellow toner is accommodated in the developing device 4Y. The yellow toner is triboelectrically charged by being agitated inside the developing device 4Y, and has a charge of the same polarity (negative polarity) as the charged electric charge on the latent image holding body 1Y, and a developer roll (developer holding) Is held on the body). Then, as the surface of the latent image holding body 1Y passes through the developing device 4Y, yellow toner electrostatically adheres to the latent image portion on the surface of the latent image holding body 1Y, and the electrostatic charge image becomes yellow. Developed with toner. The latent image holding body 1Y on which the yellow toner image is formed continues to run at a predetermined speed, and the toner image developed on the latent image holding body 1Y is conveyed to a predetermined primary transfer position.

When the yellow toner image on the latent image holding body 1Y is conveyed to the primary transfer, a predetermined primary transfer bias is applied to the primary transfer roller 5Y, and the latent image holding body 1Y moves toward the primary transfer roller 5Y. The electrostatic force is applied to the toner image, and the toner image on the latent image holding body 1Y is transferred onto the intermediate transfer belt 20. The transfer bias applied at this time is a (+) polarity opposite to the polarity (−) of the toner, and is controlled to about +10 μA by the control unit (not shown) in the first unit 10Y, for example.
On the other hand, the toner remaining on the latent image holder 1Y is removed and collected by the cleaning device 6Y.

Further, the primary transfer bias applied to the primary transfer rollers 5M, 5C, and 5K after the second unit 10M is also controlled according to the first unit.
Thus, the intermediate transfer belt 20 onto which the yellow toner image has been transferred by the first unit 10Y is sequentially conveyed through the second to fourth units 10M, 10C, and 10K, and the toner images of the respective colors are superimposed and transferred in a multiple manner.

  The intermediate transfer belt 20 onto which the four color toner images have been transferred in a multiple manner through the first to fourth units is disposed on the surface of the intermediate transfer belt 20, the support roller 24 in contact with the inner surface of the intermediate transfer belt 20, and the surface of the intermediate transfer belt 20. The secondary transfer roller (secondary transfer unit) 26 arranged to the secondary transfer portion is provided. On the other hand, a recording sheet (recording medium) P is fed at a predetermined timing into a gap where the secondary transfer roller 26 and the intermediate transfer belt 20 are pressed against each other via a supply mechanism, and a predetermined secondary transfer bias is applied. Applied to the support roller 24. The transfer bias applied at this time is a (−) polarity that is the same polarity as the polarity (−) of the toner, and an electrostatic force from the intermediate transfer belt 20 toward the recording paper P is applied to the toner image, and the transfer bias is applied to the intermediate transfer belt 20. The toner image is transferred onto the recording paper P. Note that the secondary transfer bias at this time is determined according to the resistance detected by a resistance detecting means (not shown) for detecting the resistance of the secondary transfer portion, and is voltage-controlled.

Thereafter, the recording paper P is sent to a fixing device (fixing means) 28, where the toner image is heated, and the color-superposed toner image is melted and fixed on the recording paper P. The recording paper P on which the color image has been fixed is carried out toward the discharge unit, and a series of color image forming operations is completed.
The image forming apparatus exemplified above is configured to transfer the toner image onto the recording paper P via the intermediate transfer belt 20, but is not limited to this configuration, and the toner is directly applied from the latent image holding member. A structure in which an image is transferred to a recording sheet may be used.

<Developer cartridge>
As the developer cartridge, the developer of this embodiment is accommodated, and the developer is supplied to developing means for developing the electrostatic image formed on the latent image holding member to form a toner image, thereby forming an image. A configuration that can be attached to and detached from the apparatus is included. When the developer stored in the developer cartridge becomes low, the developer cartridge is replaced.

<Process cartridge>
FIG. 2 is a schematic configuration diagram showing an embodiment of a preferred example of a process cartridge containing a developer for developing an electrostatic image according to this embodiment. The process cartridge 200 combines the developing device 111 with the photosensitive member 107, the charging roller 108, the photosensitive member cleaning device 113, the opening 118 for exposure, and the opening 117 for static elimination exposure using the mounting rail 116. , And integrated. In FIG. 2, reference numeral 300 denotes a recording paper (recording medium).
The process cartridge 200 is detachable from an image forming apparatus main body including a transfer device 112, a fixing device 115, and other components (not shown). It forms a forming apparatus.

  The process cartridge 200 shown in FIG. 2 includes a photoconductor 107, a charging roller 108, a developing device 111, a cleaning device 113, an opening 118 for exposure, and an opening 117 for static elimination exposure. The devices may be selectively combined. In the process cartridge according to the present embodiment, in addition to the developing device 111, the photosensitive member 107, the charging roller 108, the cleaning device (cleaning means) 113, the opening 118 for exposure, and the opening for static elimination exposure. You may provide at least 1 sort (s) selected from the group comprised from 117.

    Hereinafter, although an Example and a comparative example are given and this embodiment is described in detail in detail, this embodiment is not limited to the following examples.

(Magnetic core material 1)
Fe ₂ O ₃ 1460 parts by mass, Mn _(OH) 2 444 parts by weight, Mg _(OH) 2 96 parts by weight, were mixed _SiO 2 50 parts by weight, and 10 hours mixed / pulverized by a wet ball mill. Next, after granulating and drying with a spray dryer, pre-baking 1 was performed at 900 ° C. for 6 hours using a rotary kiln. The calcined product 1 thus obtained was pulverized for 2 hours with a wet ball mill to an average particle size of 2 μm, further granulated and dried with a spray dryer, and then calcined at 950 ° C. for 6 hours with a rotary kiln 2 Went. The calcined product 2 thus obtained was pulverized for 5 hours with a wet ball mill to an average particle size of 5 μm, further granulated and dried with a spray dryer, and then heated to 1200 ° C. with an electric furnace for 5 hours. Went. A magnetic core material 1 having a volume average particle size of 35 μm was prepared through a crushing step and a classification step. The obtained magnetic core material 1 had a BET specific surface area of 0.17 m ² / g.

(Magnetic core material 2)
Fe ₂ O ₃ 1442 parts by mass, Mn (OH) ₂ 410 parts by mass, Mg (OH) ₂ 146 parts by mass, and SiO ₂ 50 parts by mass were mixed and mixed / pulverized in a wet ball mill for 10 hours. Next, after granulating and drying with a spray dryer, pre-baking 1 was performed at 900 ° C. for 6 hours using a rotary kiln. The calcined product 1 thus obtained was pulverized for 2 hours with a wet ball mill to an average particle size of 2 μm, further granulated and dried with a spray dryer, and then calcined at 950 ° C. for 6 hours with a rotary kiln 2 Went. The calcined product 2 thus obtained was pulverized for 5 hours with a wet ball mill to an average particle size of 5 μm, further granulated and dried with a spray dryer, and then heated to 1190 ° C. with an electric furnace for 6 hours. Went. A magnetic core material 2 having a volume average particle size of 35 μm was prepared through a crushing step and a classification step. The obtained magnetic core material 2 had a BET specific surface area of 0.19 m ² / g.

(Magnetic core 3)
Fe ₂ O ₃ 1442 parts by mass, Mn (OH) ₂ 410 parts by mass, Mg (OH) ₂ 146 parts by mass, and SiO ₂ 60 parts by mass were mixed and mixed / pulverized in a wet ball mill for 10 hours. Next, after granulating and drying with a spray dryer, pre-baking 1 was performed at 900 ° C. for 6 hours using a rotary kiln. The calcined product 1 thus obtained was pulverized for 2 hours with a wet ball mill to an average particle size of 2 μm, further granulated and dried with a spray dryer, and then calcined at 920 ° C. for 6 hours with a rotary kiln 2 Went. The calcined product 2 thus obtained was pulverized for 5 hours with a wet ball mill to an average particle size of 5 μm, further granulated and dried with a spray dryer, and then heated to 1190 ° C. with an electric furnace for 6 hours. Went. A magnetic core material 3 having a volume average particle size of 35 μm was prepared through a crushing step and a classification step. The obtained magnetic core material 3 had a BET specific surface area of 0.21 m ² / g.

(Magnetic core 4)
Fe ₂ O ₃ 1460 parts by mass, Mn (OH) ₂ 444 parts by mass, Mg (OH) ₂ 96 parts by mass, and SiO ₂ 60 parts by mass were mixed and pulverized for 10 hours by a wet ball mill. Next, after granulating and drying with a spray dryer, pre-baking 1 was performed at 900 ° C. for 6 hours using a rotary kiln. The calcined product 1 thus obtained was pulverized for 8 hours with a wet ball mill to an average particle size of 1.5 μm, further granulated and dried with a spray dryer, and then temporarily heated at 950 ° C. for 5 hours using a rotary kiln. Firing 2 was performed. The calcined product 2 obtained in this way was pulverized for 10 hours with a wet ball mill to an average particle size of 3.8 μm, further granulated and dried with a spray dryer, and then brought to a temperature of 1200 ° C. with an electric furnace. Firing was performed for 5 hours. A magnetic core material 4 having a volume average particle size of 25 μm was prepared through a crushing step and a classification step. The obtained magnetic core material 4 had a BET specific surface area of 0.28 m ² / g.

(Magnetic core 5)
Fe ₂ O ₃ 1460 parts by mass, Mn _(OH) 2 444 parts by weight, Mg _(OH) 2 96 parts by weight, were mixed _SiO 2 50 parts by weight, and 10 hours mixed / pulverized by a wet ball mill. Next, after granulating and drying with a spray dryer, pre-baking 1 was performed at 900 ° C. for 6 hours using a rotary kiln. The calcined product 1 thus obtained was pulverized for 2 hours with a wet ball mill to an average particle size of 2 μm, further granulated and dried with a spray dryer, and then calcined at 960 ° C. for 6 hours with a rotary kiln 2 Went. The calcined product 2 thus obtained was pulverized for 2 hours with a wet ball mill to an average particle size of 6 μm, further granulated and dried with a spray dryer, and then heated to 1220 ° C. with an electric furnace for 5 hours. Went. A magnetic core material 5 having a volume average particle size of 40 μm was prepared through a crushing step and a classification step. The obtained magnetic core material 5 had a BET specific surface area of 0.13 m ² / g.

(Magnetic core 6)
Fe ₂ O ₃ 1460 parts by mass, Mn (OH) ₂ 444 parts by mass, Mg (OH) ₂ 96 parts by mass, and SiO ₂ 60 parts by mass were mixed and pulverized for 10 hours by a wet ball mill. Next, after granulating and drying with a spray dryer, pre-baking 1 was performed at 900 ° C. for 6 hours using a rotary kiln. The calcined product 1 thus obtained was pulverized for 8 hours with a wet ball mill to an average particle size of 1.5 μm, further granulated and dried with a spray dryer, and then temporarily heated at 950 ° C. for 5 hours using a rotary kiln. Firing 2 was performed. The calcined product 2 thus obtained was pulverized with a wet ball mill for 10 hours to an average particle size of 3.8 μm, further granulated and dried with a spray dryer, and then heated to 1210 ° C. with an electric furnace for 5 hours. Was fired. A magnetic core material 6 having a volume average particle size of 25 μm was prepared through a crushing step and a classification step. The obtained magnetic core material 6 had a BET specific surface area of 0.30 m ² / g.

(Magnetic core 7)
Fe ₂ O ₃ 1460 parts by mass, Mn (OH) ₂ 444 parts by mass, Mg (OH) ₂ 96 parts by mass, and SiO ₂ 60 parts by mass were mixed and pulverized for 10 hours by a wet ball mill. Next, after granulating and drying with a spray dryer, pre-baking 1 was performed at 900 ° C. for 6 hours using a rotary kiln. The calcined product 1 thus obtained was pulverized for 2 hours with a wet ball mill to an average particle size of 2 μm, further granulated and dried with a spray dryer, and then calcined at 960 ° C. for 6 hours with a rotary kiln 2 Went. The calcined product 2 thus obtained was pulverized for 2 hours with a wet ball mill to an average particle size of 6 μm, further granulated and dried with a spray dryer, then heated to 1220 ° C. with an electric furnace and fired for 6 hours. Went. A magnetic core material 7 having a volume average particle size of 41 μm was prepared through a crushing step and a classification step. The obtained magnetic core material 7 had a BET specific surface area of 0.10 m ² / g.

(Magnetic core 8)
Fe ₂ O ₃ 1930 parts by mass, Mn (OH) ₂ 60 parts by mass, Mg (OH) ₂ 10 parts by mass, SrCO ₃ 124 parts by mass, TiO ₂ 70 parts by mass were mixed and pulverized by a wet ball mill for 10 hours. . Next, after granulating and drying with a spray dryer, pre-baking was performed at 900 ° C. for 6 hours using a rotary kiln. The calcined product 1 thus obtained was pulverized for 2 hours with a wet ball mill to an average particle size of 2 μm, further granulated and dried with a spray dryer, then heated to 1200 ° C. with an electric furnace and baked for 6 hours. Went. A magnetic core material 8 having a volume average particle size of 35 μm was prepared through a crushing step and a classification step. The obtained magnetic core material 8 had a BET specific surface area of 0.10 m ² / g.

(Magnetic core 9)
Phenol 40 parts by mass, formalin 60 parts by mass, magnetite (volume average particle size 0.2 μm) 400 parts by mass, strontium ferrite (volume average particle size 0.3 μm) 40 parts by mass, ion-exchanged water 60 parts by mass, ammonia water 12 Mass parts were added, the temperature was gradually raised to 85 ° C. while mixing and stirring, and the reaction and curing were performed over 4 hours. Thereafter, cooling, filtration, and washing with ion exchange water were performed. Next, the temperature was gradually raised to 180 ° C. and dried to obtain a magnetic core material 9 having a volume average particle size of 35.0 μm. The obtained magnetic core material 9 had a BET specific surface area of 0.08 m ² / g.

(Magnetic core 10)
Fe ₂ O ₃ 1318 parts by mass, Mn _(OH) 2 586 parts by weight, Mg _(OH) 2 96 parts by weight, were mixed _SiO 2 60 parts by weight, and 10 hours mixed / pulverized by a wet ball mill. Next, after granulating and drying with a spray dryer, pre-baking 1 was performed at 900 ° C. for 6 hours using a rotary kiln. The calcined product 1 thus obtained was pulverized for 6 hours with a wet ball mill to an average particle size of 2 μm, further granulated and dried with a spray dryer, and then calcined at 960 ° C. for 5 hours with a rotary kiln 2 Went. The calcined product 2 thus obtained was pulverized with a wet ball mill for 10 hours to an average particle size of 3.8 μm, further granulated and dried with a spray dryer, and then heated to 1210 ° C. with an electric furnace for 5 hours. Was fired. A magnetic core material 10 having a volume average particle size of 35 μm was prepared through a crushing step and a classification step. The obtained magnetic core material 10 had a BET specific surface area of 0.18 m ² / g.

(Magnetic core 11)
Fe ₂ O ₃ 1678 parts by mass, Mn (OH) ₂ 224 parts by mass, Mg (OH) ₂ 98 parts by mass, and SiO ₂ 40 parts by mass were mixed and pulverized with a wet ball mill for 10 hours. Next, after granulating and drying with a spray dryer, pre-baking 1 was performed at 900 ° C. for 6 hours using a rotary kiln. The calcined product 1 thus obtained was pulverized for 6 hours with a wet ball mill to an average particle size of 2 μm, further granulated and dried with a spray dryer, and then calcined at 940 ° C. for 5 hours using a rotary kiln. Went. The calcined product 2 thus obtained was pulverized for 10 hours with a wet ball mill to an average particle size of 3.8 μm, further granulated and dried with a spray dryer, and then set at a temperature of 1990 ° C. with an electric furnace for 5 hours. Was fired. A magnetic core material 11 having a volume average particle size of 35 μm was prepared through a crushing step and a classification step. The obtained magnetic core material 11 had a BET specific surface area of 0.16 m ² / g.

(Magnetic core 12)
A magnetic core material 12 was produced in the same manner as the magnetic core material 8 except that in the preparation of the magnetic core material 8, the firing conditions were changed to a temperature of 1100 ° C. and 4.5 hours. The volume average particle diameter of the magnetic core material 12 was 35 μm, and the BET specific surface area was 0.19 m ² / g.

Tables 1 to 3 show the ratio (A / D50) of the volume average particle diameter D50 (μm) to the BET specific surface area A (m ² / g) in the magnetic core material 1 to magnetic core material 12 and included in the magnetic core material. Details of the ferrite to be used are described.

(Liquid for film formation 1)
Styrene-methyl methacrylate copolymer (85:15) Weight average molecular weight 40,000: 36 parts by mass Carbon black VXC72 (cabot): 4 parts by mass Toluene: 250 parts by mass Isopropyl alcohol: 50 parts by mass Glass beads (particle size: 1 mm, same amount as toluene (mass basis)) were placed in a sand mill manufactured by Kansai Paint Co., Ltd., and stirred at a rotational speed of 1200 rpm for 30 minutes to prepare a film forming solution 1 having a solid content of 11%.

(Film forming liquid 2)
Styrene-methyl methacrylate copolymer (85:15) Weight average molecular weight 40,000: 36 parts by mass Carbon black VXC72 (Cabot): 3 parts by mass Strontium titanate: 5 parts by mass Toluene: 240 parts by mass Isopropyl Alcohol: 50 parts by mass The above components and glass beads (particle size: 1 mm, the same amount as toluene (mass basis)) are put into a sand mill manufactured by Kansai Paint Co., Ltd., and stirred for 30 minutes at a rotational speed of 1200 rpm, and a coating film having a solid content of 10% A forming liquid 2 was prepared.

(Carrier 1)
2000 g of magnetic core material 1 is put into a vacuum degassing type 5 L kneader, and further 380 g of film forming liquid 1 is put into the vacuum deaeration type 5 L kneader. The mixture was stirred and dried at 90 ° C./−720 mHg for 30 minutes to obtain coated particles. Next, sieving was performed with a 75 μm mesh sieving net to obtain Carrier 1.

(Carrier 2)
A carrier 2 was obtained in the same manner as in the carrier 1 except that the magnetic core material 1 was replaced with the magnetic core material 2.
(Carrier 3)
A carrier 3 was obtained in the same manner as in the carrier 1 except that the magnetic core material 1 was replaced with the magnetic core material 3.
(Carrier 4)
A carrier 4 was obtained in the same manner as in the carrier 1 except that the magnetic core material 1 was replaced with the magnetic core material 4.
(Carrier 5)
A carrier 5 was obtained in the same manner as in the carrier 1 except that the magnetic core material 1 was replaced with the magnetic core material 5.
(Carrier 6)
In the carrier 1, the carrier 6 was obtained in the same manner except that the magnetic core material 1 was replaced with the magnetic core material 6.
(Carrier 7)
A carrier 7 was obtained in the same manner as in the carrier 1 except that the magnetic core material 1 was replaced with the magnetic core material 7.
(Carrier 8)
In the carrier 1, the carrier 8 was obtained in the same manner except that the magnetic core material 1 was replaced with the magnetic core material 8 and the film forming liquid 1 was replaced with the film forming liquid 2.
(Carrier 9)
A carrier 9 was obtained in the same manner as in the carrier 1 except that the magnetic core material 1 was replaced with the magnetic core material 9.
(Carrier 10)
A carrier 10 was obtained in the same manner as in the carrier 1 except that the magnetic core material 1 was replaced with the magnetic core material 10.
(Carrier 11)
In the carrier 1, the carrier 11 was obtained in the same manner except that the magnetic core material 1 was replaced with the magnetic core material 11.
(Carrier 12)
In the carrier 1, the carrier 12 was obtained in the same manner except that the magnetic core material 1 was replaced with the magnetic core material 12.

<Creation of toner 1>
(Colorant dispersion 1)
-Cyan pigment: Copper phthalocyanine B15: 3 (Daiichi Seika): 50 parts by mass-Anionic surfactant: Neogen SC (Daiichi Kogyo Seiyaku): 5 parts-Ion-exchanged water: 200 parts by weight Then, the dispersion was dispersed for 5 minutes with an Ultra-Turrax manufactured by IKA and for 10 minutes with an ultrasonic bath to obtain a colorant dispersion 1 having a solid content of 21%. It was 160 nm when the volume average particle diameter was measured with a Horiba Seisakusho particle size measuring instrument LA-700.

(Releasing agent dispersion 1)
-Paraffin wax: HNP-9 (Nippon Seiki): 19 parts by mass-Anionic surfactant: Neogen SC (Daiichi Kogyo Seiyaku): 1 part by mass-Ion-exchanged water: 80 parts by mass The mixture was mixed, heated to 90 ° C., and stirred for 30 minutes. Next, the molten liquid is circulated from the bottom of the container to the gorin homogenizer, and under a pressure condition of 5 MPa, a circulation operation corresponding to 3 passes is performed. Then, the pressure is increased to 35 MPa, and further a circulation operation corresponding to 3 passes is performed. It was. The emulsion thus prepared was cooled in the heat-resistant solution to 40 ° C. or lower to obtain a release agent dispersion 1. It was 240 nm when the volume average particle diameter was measured with a Horiba Seisakusho particle size measuring instrument LA-700.

(Binder resin particle dispersion 1)
-Oil layer-
・ Styrene (manufactured by Wako Pure Chemical Industries, Ltd.): 30 parts by mass n-butyl acrylate (manufactured by Wako Pure Chemical Industries, Ltd.): 10 parts by mass ・ β-carboxyethyl acrylate (manufactured by Rhodia Nikka Co., Ltd.): 1.3 parts by mass / dodecanethiol (manufactured by Wako Pure Chemical Industries, Ltd.): 0.4 parts by mass-water layer 1-
-Ion exchange water: 17 parts by mass-Anionic surfactant (Dowfax, manufactured by Dow Chemical): 0.4 part by mass-aqueous layer 2-
-Ion exchange water: 40 parts by mass-Anionic surfactant (Dowfax, manufactured by Dow Chemical): 0.05 parts by mass-Ammonium peroxodisulfate (manufactured by Wako Pure Chemical Industries, Ltd.): 0.4 parts by mass

The oil layer component and the water layer 1 component were placed in a flask and mixed with stirring to obtain a monomer emulsion. The components of the aqueous layer 2 were charged into the reaction vessel, the inside of the vessel was replaced with nitrogen, and the reaction system was heated to 75 ° C. with an oil bath while stirring. The above-mentioned monomer emulsion was gradually dropped into the reaction vessel over 3 hours to carry out emulsion polymerization. After completion of the dropping, the polymerization was further continued at 75 ° C., and the polymerization was terminated after 3 hours.
The obtained resin particles were 250 nm when the volume average particle diameter D50 of the resin particles was measured with a particle size measuring instrument LA-700 manufactured by Horiba, Ltd., and the temperature was raised using a differential scanning calorimeter (DSC-50 manufactured by Shimadzu Corporation). When the glass transition temperature of the resin was measured at a rate of 10 ° C./min, it was 53 ° C., and the number average molecular weight (polystyrene conversion) was measured using THF as a solvent using a molecular weight measuring instrument (HLC-8020 manufactured by Tosoh Corporation). 000. As a result, a binder resin particle dispersion 1 having a volume average particle size of 250 nm, a solid content of 42%, a glass transition temperature of 52 ° C., and a number average molecular weight Mn of 13,000 was obtained.

(Toner 1)
-Binder resin particle dispersion 1: 150 parts by mass-Colorant dispersion 1: 30 parts by mass-Release agent dispersion 1: 40 parts by mass-Polyaluminum chloride: 0.4 parts by mass After mixing and dispersing using IKE's Ultra Turrax, the flask was heated to 48 ° C. with stirring in an oil bath for heating. After holding at 48 ° C. for 80 minutes, 70 parts by mass of the binder resin particle dispersion 1 was gently added thereto.
Then, after adjusting the pH in the system to 6.0 using a sodium hydroxide aqueous solution having a concentration of 0.5 mol / L, the stainless steel flask was sealed, and the stirring shaft seal was magnetically sealed while stirring was continued. Heat to 97 ° C. and hold for 3 hours. After completion of the reaction, the temperature lowering rate was cooled at 1 ° C./min, filtered, washed with ion-exchanged water, and solid-liquid separation was performed by Nutsche suction filtration. This was further redispersed using 3 L of ion exchange water at 40 ° C., and stirred and washed at 300 rpm for 15 minutes. This washing operation was further repeated 5 times. When the pH of the filtrate was 6.54 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 particles.
The volume average particle diameter D50 of the toner particles was measured by Coulter Multisizer II and found to be 6.2 μm and the volume average particle size distribution index GSDv was 1.20. When the shape was observed with a Luzex image analyzer manufactured by Luzex, the shape factor SF1 of the particles was 135, and it was observed that the particles had a potato shape. The glass transition temperature of the toner particles was 52 ° C. Further, silica particles (SiO ₂ ) having a primary particle average particle size of 40 nm, surface-hydrophobized with hexamethyldisilazane (hereinafter sometimes abbreviated as “HMDS”), metatitanic acid and isobutyltrimethoxy are added to the toner particles. Toner 1 was prepared by adding metatitanic acid compound particles having a primary particle average particle diameter of 20 nm, which is a reaction product of silane, so that the coverage of the surface of the toner particles was 40%, and mixing with a Henschel mixer.

Note that GSDv, which is an index of volume particle size distribution, is obtained by the equation “GSDv = (D84v / D16v) ^1/2 ”. Here, D84v is a particle size value that is 84% cumulative from the small diameter side in the volume distribution of particle size, and D16v is a particle size value that is cumulative 16% from the small diameter side in the volume distribution of particle size.
D16v and D84v were measured with a Coulter Multisizer II (manufactured by Coulter).

<Creation of toner 2>
(Binder resin particle dispersion 2)
・ Ethylene glycol (manufactured by Wako Pure Chemical Industries, Ltd.): 37 parts by mass ・ Neopentyl glycol (manufactured by Wako Pure Chemical Industries, Ltd.): 65 parts by mass ・ 1,9-nonanediol (Wako Pure Chemical Industries, Ltd.) Manufactured): 32 parts by mass, terephthalic acid (manufactured by Wako Pure Chemical Industries, Ltd.): 96 parts by mass The above components were charged into a flask and the temperature was raised to 200 ° C. over 1 hour, and the reaction system was uniformly stirred. Then, 1.2 parts by mass 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 temperature of 62 ° C. was obtained. Next, this was transferred in a molten state to Cavitron CD1010 (manufactured by Eurotech Co., Ltd.) at a rate of 100 g / min. A 0.37% by mass diluted ammonia water obtained by diluting reagent ammonia water with ion-exchanged water is placed in a separately prepared aqueous medium tank, and heated at 120 ° C. with a heat exchanger at a rate of 0.1 liter per minute. Simultaneously with the polyester resin melt, it was transferred to the Cavitron. A Cavitron is operated under the conditions of a rotor rotation speed of 60 Hz and a pressure of 5 kg / cm ^2. Dispersion of a resin having an average particle diameter of 160 nm, a solid content of 30%, a glass transition temperature of 62 ° C., and a weight average molecular weight Mw of 13,000. A liquid (binder resin particle dispersion 2) was obtained.

(Colorant dispersion 2)
-Cyan pigment (Pigment Blue 15: 3, manufactured by Dainichi Seika Kogyo Co., Ltd.): 20 parts by mass-Anionic surfactant (Neogen SC, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.): 2 parts by mass-Ion-exchanged water: 80 Part by mass The above components were mixed and dispersed for 1 hour using a high-pressure impact disperser ultimateizer (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%. .

(Binder resin particle dispersion 3)
Decanedioic acid (manufactured by Tokyo Chemical Industry Co., Ltd.): 81 parts by mass Hexanediol (manufactured by Wako Pure Chemical Industries, Ltd.): 47 parts by mass The above components are charged into a flask and heated to 160 ° C. over 1 hour. After confirming that the reaction system was uniformly stirred, 0.03 parts by mass of dibutyltin oxide was added. Further, while distilling off the water produced, the temperature was raised from the same temperature to 200 ° C. over 6 hours, and the dehydration condensation reaction was continued at 200 ° C. for another 4 hours to complete the reaction. After cooling the reaction solution, the solid obtained by solid-liquid separation was dried at 40 ° C. under vacuum to obtain a binder resin 3.
The melting temperature of the obtained binder resin 3 was 64 ° C. as a result of measurement using a differential thermal scanning calorimeter DSC-7 manufactured by Perkinelmer. The weight average molecular weight was 15000 as measured using a molecular weight measuring device HLC-8020 manufactured by Tosoh Corporation using tetrahydroxyfuran (THF) as a solvent.

-Binder resin 3: 50 parts by mass-Anionic surfactant (Neogen SC, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.): 2 parts by mass-Ion-exchanged water: 200 parts by mass The above components are heated to 120 ° C. After dispersion with IKE Ultra Turrax T50, the mixture was dispersed with a pressure discharge homogenizer and collected when the volume average particle size reached 180 nm. Thus, a binder resin particle dispersion 3 having a solid content of 20% was obtained.

(Releasing agent dispersion 2)
-Paraffin wax (HNP-9 manufactured by Nippon Seiki Co., Ltd.): 50 parts by mass-Anionic surfactant (Neogen SC, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.): 2 parts by mass-Ion-exchanged water: 200 parts by mass The above components are heated to 120 ° C. and dispersed with IKE Ultra Turrax T50, and then dispersed with a pressure discharge homogenizer to obtain a release agent dispersion 2 having a volume average particle size of 200 nm and a solid content of 20%. Obtained.

(Toner 2)
-Binder resin particle dispersion 2: 150 parts by weight-Colorant dispersion 2: 25 parts by weight-Release agent dispersion 2: 35 parts by weight-Binder resin particle dispersion 3: 50 parts by weight-Polyaluminum chloride: 0.4 parts by mass / ion-exchanged water: 100 parts by mass The above ingredients were mixed and dispersed in a round stainless steel flask using IKE Ultra Turrax T50, and then the inside of the flask was stirred with a heating oil bath. While heating to 48 ° C. After maintaining at 48 ° C. for 60 minutes, 70 parts by mass of the binder resin particle dispersion 2 was gradually added thereto. Then, after adjusting the pH in the system to 8.0 using an aqueous sodium hydroxide 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 30 minutes. After completion of the reaction, the temperature was lowered at a rate of 5 ° C./min, filtered, washed with ion-exchanged water, and solid-liquid separation was performed by Nutsche suction filtration. This was further redispersed with 3 L 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, and when the pH of the filtrate became 7.54 and the electric conductivity was 6.5 μS / cm, No. was obtained by Nutsche suction filtration. Solid-liquid separation was performed using 5A filter paper. Next, vacuum drying was continued for 24 hours to obtain toner particles.
When the volume average particle diameter D50 of the toner particles is measured by Coulter Multisizer II, it is 5.7 μm and the volume average particle size distribution index GSDv is 1.20. Furthermore, the primary particle average particle size which is a reaction product of silica (SiO ₂ ) particles having a primary particle average particle size of 40 nm, which has been subjected to surface hydrophobization treatment with hexamethyldisilazane, and metatitanic acid and isobutyltrimethoxysilane. Toner 2 was prepared by adding 20 nm of metatitanic acid compound particles so that the coverage with respect to the surface of the toner particles was 40% and mixing with a Henschel mixer.

(Developer 1)
16 g of toner 2 and 184 g of carrier 1 were mixed and stirred to obtain developer 1. Developer 1 had a relative dielectric constant of 18 and tan δ of 0.05.
(Developer 2)
16 g of toner 2 and 184 g of carrier 2 were mixed and stirred to obtain developer 2. The relative dielectric constant of Developer 2 was 12, and tan δ was 0.05.
(Developer 3)
16 g of toner 2 and 184 g of carrier 3 were mixed and stirred to obtain developer 3. The relative dielectric constant of Developer 3 was 18, and tan δ was 0.07.
(Developer 4)
16 g of toner 2 and 184 g of carrier 4 were mixed and stirred to obtain developer 4. The relative dielectric constant of Developer 4 was 18, and tan δ was 0.05.
(Developer 5)
16 g of toner 2 and 184 g of carrier 5 were mixed and stirred to obtain developer 5. The relative dielectric constant of Developer 5 was 18, and tan δ was 0.05.
(Developer 6)
16 g of toner 2 and 184 g of carrier 6 were mixed and stirred to obtain developer 6. The relative dielectric constant of developer 6 was 18, and tan δ was 0.05.
(Developer 7)
16 g of toner 2 and 184 g of carrier 7 were mixed and stirred to obtain developer 7. The relative dielectric constant of developer 7 was 18, and tan δ was 0.05.
(Developer 8)
16 g of toner 2 and 184 g of carrier 8 were mixed and stirred to obtain developer 8. The relative dielectric constant of Developer 8 was 24 and tan δ was 0.05.
(Developer 9)
16 g of toner 2 and 184 g of carrier 9 were mixed and stirred to obtain developer 9. The relative dielectric constant of developer 9 was 10, and tan δ was 0.05.
(Developer 10)
16 g of toner 2 and 184 g of carrier 10 were mixed and stirred to obtain developer 10. The relative dielectric constant of developer 10 was 16, and tan δ was 0.1.
(Developer 11)
16 g of toner 2 and 184 g of carrier 11 were mixed and stirred to obtain developer 11. The relative dielectric constant of developer 11 was 19 and tan δ was 0.008.
(Developer 12)
16 g of toner 1 and 184 g of carrier 1 were mixed and stirred to obtain developer 12. The relative dielectric constant of developer 12 was 18, and tan δ was 0.06.
(Developer 13)
16 g of toner 2 and 184 g of carrier 12 were mixed and stirred to obtain developer 13. The relative dielectric constant of developer 13 was 20, and tan δ was 0.05.

[Example 1]
DocuCentre Color 400 remodeling machine (when black alone is printed, yellow / magenta / cyan developer is accompanied and no new toner is supplied to the cyan developer), and developer 1 is charged into the cyan developer. The developer was charged with DocuCentre Color 400 original developer. Thereafter, it was left for 12 hours in an environment of 30 ° C. and 88% RH. Thereafter, 1000 sheets of black A4 images with a toner applied amount of 6 g / m ² were continuously printed (the cyan developing unit was being followed by the black developing unit). Next, five cyan single prints of 10 cm × 10 cm solid patches were performed. Then, it left still for one week under the same environment. After standing, 10 sheets of white paper were continuously output while the cyan developing unit was driven alone.
As a result, the continuous output was good with no visible fog from the first sheet. ... ◎

[Example 2]
Evaluation was conducted in the same manner as in Example 1 except that Developer 2 was used instead of Developer 1. As a result, no fog was visually observed on the second sheet in continuous output. ... ◎

[Example 3]
Evaluation was conducted in the same manner as in Example 1 except that Developer 3 was used instead of Developer 1. As a result, no fogging was visually observed on the third sheet with continuous output. ... ◎

[Example 4]
Evaluation was conducted in the same manner as in Example 1 except that Developer 4 was used instead of Developer 1. As a result, no fog was visually observed on the fifth sheet in continuous output.・ ・ ・ ○

[Example 5]
Evaluation was conducted in the same manner as in Example 1 except that Developer 5 was used instead of Developer 1. As a result, no fog was visually observed on the sixth sheet at continuous output.・ ・ ・ ○

[Example 6]
Evaluation was conducted in the same manner as in Example 1 except that Developer 6 was used instead of Developer 1. As a result, no fog was visually observed on the eighth sheet in continuous output. ... △

[Example 7]
Evaluation was conducted in the same manner as in Example 1 except that Developer 7 was used instead of Developer 1. As a result, no fog was visually observed on the ninth sheet in continuous output. ... △

[Example 8]
Evaluation was performed in the same manner as in Example 1 except that the developer 12 was used instead of the developer 1. As a result, no fogging was visually observed on the third sheet with continuous output. ... ◎

[Example 9]
Evaluation was performed in the same manner as in Example 1 except that developer 13 was used instead of developer 1. As a result, no fog was visually observed on the seventh sheet in continuous output. ... △

[Comparative Example 1]
Evaluation was conducted in the same manner as in Example 1 except that Developer 8 was used instead of Developer 1. As a result, even when the 10th sheet was printed with continuous output, fogging was visually observed, and the fogging level was severe. ... XX

[Comparative Example 2]
Evaluation was conducted in the same manner as in Example 1 except that Developer 9 was used instead of Developer 1. As a result, fogging was visually observed on the 10th sheet with continuous output. ... ×

[Comparative Example 3]
Evaluation was conducted in the same manner as in Example 1 except that Developer 10 was used instead of Developer 1. As a result, fogging was visually observed on the 10th sheet with continuous output. ... ×

[Comparative Example 4]
Evaluation was conducted in the same manner as in Example 1 except that Developer 11 was used instead of Developer 1. As a result, even when the 10th sheet was printed with continuous output, fogging was visually observed, and the fogging level was severe. ... XX

1Y, 1M, 1C, 1K, 107 photoconductor (latent image holder)
2Y, 2M, 2C, 2K, 108 Charging roller 3Y, 3M, 3C, 3K Laser beam 3 Exposure device 4Y, 4M, 4C, 4K, 111 Developing device (developing means)
5Y, 5M, 5C, 5K Primary transfer rollers 6Y, 6M, 6C, 6K, 113 Latent image carrier cleaning device (cleaning means)
8Y, 8M, 8C, 8K Developer cartridge 10Y, 10M, 10C, 10K Image forming unit 20 Intermediate transfer belt 22 Drive roller 24 Support roller 26 Secondary transfer rollers 28, 115 Fixing device (fixing means)
30 Intermediate transfer member cleaning device 112 Transfer device 116 Mounting rail 117 Opening portion 118 for static elimination exposure Opening portion 200 for exposure Process cartridge P, 300 Recording paper (recording medium)

Claims (8)

A developer containing a carrier and a toner,
A developer for developing an electrostatic charge image, having a relative dielectric constant ε ′ of 12 or more and 22 or less and tan δ of 0.01 or more and 0.07 or less when the concentration of the toner with respect to the developer is 8% by mass. The carrier is a resin-coated carrier having a magnetic core material and a resin coating layer covering the magnetic core material;
The magnetic core material includes ferrite represented by the following formula (1), and the content of Si, Sr or Ti in the magnetic core material is 0.05 mol or more and 0.4 mol or less with respect to 1 mol of Fe. The developer for developing an electrostatic image according to claim 1.
(MO) _X (Fe ₂ O ₃ ) _Y formula (1)
[In Formula (1), Y represents 2.1 or more and 2.4 or less, and X represents 3-Y. M represents a metal element, and contains at least Mn as the metal element. ] The developer for developing an electrostatic charge image according to claim 2, wherein a volume average particle diameter D50 (μm) and a BET specific surface area A (m ² / g) of the magnetic core material satisfy the following formula (2).
0.003 ≦ A / D50 ≦ 0.011 Formula (2)   The developer for electrostatic image development according to any one of claims 1 to 3, wherein the toner contains a crystalline polyester resin. The toner is
An agglomerated particle forming step of forming an agglomerated particle by adding an aggregating agent to a mixed dispersion obtained by mixing at least a binder resin particle dispersion in which a binder resin particle is dispersed and a colorant dispersion in which a colorant is dispersed;
An attaching step of further adding the binder resin particle dispersion to the mixed dispersion in which the aggregated particles are formed, and attaching the binder resin particles to the surface of the aggregated particles to form resin-attached aggregated particles; ,
A fusion step of fusing the resin-adhered aggregated particles by heating;
The developer for developing an electrostatic charge image according to any one of claims 1 to 4, comprising toner particles produced through the process.   A process cartridge comprising at least a developer holder and containing the developer for developing an electrostatic charge image according to any one of claims 1 to 5.   The latent image holding member, a charging unit for charging the surface of the latent image holding member, an electrostatic charge image forming unit for forming an electrostatic charge image on the surface of the latent image holding member, and the electrostatic charge image. 5. A developing unit that forms a toner image by developing with the developer for developing an electrostatic charge image according to claim 5; a transfer unit that transfers the toner image to a recording medium; and the toner image on the recording medium. An image forming apparatus comprising: a fixing unit that fixes the image;   The charging step for charging the surface of the latent image holding member, the electrostatic charge image forming step for forming an electrostatic charge image on the surface of the latent image holding member, and the electrostatic charge image according to any one of claims 1 to 5. A developing process for forming a toner image by developing with the developer for developing an electrostatic charge image, a transfer process for transferring the toner image to a recording medium, and a fixing process for fixing the toner image on the recording medium. An image forming method.