JP2012053300A - Developer for electrostatic latent image development, developer cartridge, process cartridge and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developer for electrostatic latent image development, suppressing variation in image density depending on a number of prints.SOLUTION: The developer for electrostatic latent image development comprises: a toner having an external additive on the surface thereof, the external additive having a number average particle diameter of 50 nm or more and 500 nm or less; and a carrier comprising a core and a coating layer formed on the core. The coating layer contains particles, and the carrier has projections formed on the surface thereof, the projections derived from the aforementioned particles. The number average height H of the projections from the surface of the coating layer is 1/2 or more and less than 1, in terms of a ratio, of the number average particle diameter D of the particles, as well as equal to or more than the number average particle diameter of the external additive.

Description

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

  In a method for visualizing image information through an electrostatic latent image such as electrophotography, toner is used as a developer. As this developer, there are a two-component developer composed of a toner and a carrier, and a one-component developer used alone, such as a magnetic toner.

  As the above-mentioned two-component developer, for example, a developer for developing an electrostatic charge image containing a carrier having irregularities derived from particles contained in a coat layer on a carrier surface together with a toner is disclosed (for example, see Patent Document 1). ). According to this developer, while maintaining cleaning properties, it is compatible with a low-temperature fixing system, has good offset resistance, and does not contaminate the fixing device and the image.

  In the carrier for an electrostatic latent image developer having a coating layer made of a resin and conductive powder on the carrier core, the average primary particle diameter of the conductive powder is (B) μm, and the resin coat thickness is (A). An electrostatic latent image developer carrier is disclosed in which the relationship between the two satisfies (A) ≦ (B) ≦ (A) +3 (μm) when μm (see, for example, Patent Document 2). According to this carrier, even in a coated carrier, the desired chargeability is realized, it can be easily manufactured, and the life is extended.

  Furthermore, it is a carrier having an outer shell layer provided in a form covering the spherical particles having magnetism, the outer shell layer has irregularities based on fine particles encapsulated in the layer, and An electrostatic latent image developing carrier whose outermost surface is coated with a silicone resin film is disclosed (for example, see Patent Document 3). According to this carrier, the image quality does not change even when used for a long period of time, and further, fine line reproducibility and uniform reproducibility of small-diameter dots are possible, and the resolution is excellent.

  In addition, a carrier having a core to be a core material, a coating layer formed on the surface of the core, and a plurality of convex portions formed on the surface of the coating layer is disclosed (for example, see Patent Document 4). .)

JP 2004-226506 A JP 09-160304 A JP 2002-287431 A JP 2006-18129 A

  That is, an object of the present invention is to provide a developer for developing an electrostatic latent image in which fluctuations in image density due to the number of prints are suppressed.

The above problem is solved by the following means.
The invention according to claim 1
A toner having a surface having an external additive having a number average particle diameter of 50 nm or more and 500 nm or less, and a carrier having a nucleus and a coating layer formed on the nucleus,
The coating layer includes particles;
Convex portions due to the particles are formed on the surface of the carrier, and the number average height H of the convex portions from the surface of the coating layer is not less than 1/2 and less than 1 of the number average particle diameter D of the particles. And a developer for developing an electrostatic latent image having a number average particle diameter equal to or larger than the number of the external additives.

In the invention according to claim 2, the number average height H of the protrusions from the surface of the coating layer is 3/5 or more and 4/5 or less of the number average particle diameter D of the particles. The developer for developing an electrostatic latent image.
In the invention according to claim 3, the total length of the arc where the outer peripheral portion of the coating layer and the particles intersect is 30% or more and 50% or less with respect to the outer peripheral length of the coating layer in the cross section of the carrier. The developer for developing an electrostatic latent image described in 1.

  The invention according to claim 4 is the developer for developing an electrostatic latent image according to claim 1 or 2, wherein the particles contain at least one selected from tin oxide, titanium, and copper.

  A fifth aspect of the present invention is a developer cartridge in which the developer for developing an electrostatic latent image according to any one of the first to fourth aspects is accommodated.

The invention according to claim 6
Development for developing a toner image by developing the electrostatic latent image formed on the surface of the electrostatic latent image holding member with the developer for developing an electrostatic latent image according to any one of claims 1 to 4. Equipment,
An electrostatic latent image holding body, a charging device for charging the surface of the electrostatic latent image holding body, an electrostatic latent image forming apparatus for forming an electrostatic latent image on the charged surface of the electrostatic latent image holding body, and the electrostatic At least one selected from the group consisting of transfer devices that transfer the toner image formed on the surface of the latent image carrier to the surface of the transfer target;
The process cartridge is detachable from the main body of the image forming apparatus.

The invention according to claim 7 provides:
An electrostatic latent image carrier;
A charging device for charging the electrostatic latent image holding member;
An electrostatic latent image forming apparatus that exposes the charged electrostatic latent image holding member to form an electrostatic latent image on the electrostatic latent image holding member;
A developing device that forms the toner image by developing the electrostatic latent image with the developer for developing an electrostatic latent image according to any one of claims 1 to 4.
A transfer device for transferring the toner image from the electrostatic latent image carrier to a recording medium;
A fixing device for fixing the transferred image transferred to the recording medium;
An image forming apparatus having

  According to the first aspect of the present invention, when a toner having a surface with an external additive having a number average particle diameter of 50 nm or more and 500 nm or less is used, a carrier containing particles in the coating layer is not used, or the carrier Compared with the case where the average height of the convex portions due to the particles protruding from the surface of the coating layer is less than 1/2 or more than 1 of the number average particle diameter D of the particles, fluctuations in the image density due to the number of prints are suppressed. A developer for developing an electrostatic latent image is provided.

  According to invention of Claim 2, when the number average height of the said convex part from the surface of the coating layer of a carrier is not 3/5 or more and 4/5 or less of the number average particle diameter D of this particle | grain. In comparison, there is provided a developer for developing an electrostatic latent image in which fluctuations in image density due to the number of prints are further suppressed.

  According to the invention of claim 3, when the total length of the arc where the outer peripheral portion of the coating layer and the particles intersect with the outer peripheral length of the coating layer in the cross section of the carrier is less than 30% or more than 50% In comparison with the above, there is provided a developer for developing an electrostatic latent image in which fluctuations in image density due to the number of printed images are further suppressed.

  According to the fourth aspect of the present invention, compared to the case where the particles contained in the carrier coating layer do not contain any of carbon bran tin oxide, titanium, and copper, a decrease in image density at the initial stage of use is suppressed. A developer for developing an electrostatic latent image is provided.

  According to the fifth aspect of the present invention, there is provided a developer cartridge in which fluctuations in image density due to the number of prints are suppressed as compared with the case where the specific developer for developing an electrostatic latent image is not used.

  According to the sixth aspect of the present invention, there is provided a process cartridge in which fluctuations in image density due to the number of prints are suppressed as compared with the case where the specific developer for developing an electrostatic latent image is not used.

  According to the seventh aspect of the present invention, there is provided an image forming apparatus in which fluctuations in image density due to the number of printed images are suppressed as compared with the case where the specific developer for developing an electrostatic latent image is not used.

It is a figure explaining the mode of the carrier surface concerning this embodiment, (A) is an initial stage of image output, (B) is a mode after use lapse of time. It is a schematic sectional drawing of the carrier which concerns on this embodiment. 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.

<Developer for developing electrostatic latent image>
The developer for developing an electrostatic latent image according to the exemplary embodiment includes a toner having a surface having an external additive having a number average particle diameter of 50 nm to 500 nm, a core, and a coating layer formed on the core. The coating layer includes particles, and convex portions due to the particles are formed on the surface of the carrier, and the number average height H of the convex portions from the surface of the coating layer is the number average of the particles. It is 1/2 or more of the particle diameter D and less than 1, and it is more than the number average particle diameter of the external additive.

  In order to promote the triboelectric chargeability, a so-called large particle external additive of 50 nm or more may be added to the toner. However, because of the size of the external additive of large particles, the external additive is easily detached from the toner, and the external additive detached when mixed with the carrier adheres to the surface of the carrier, resulting in an increase in the resistance of the carrier in the initial printing stage. As a result, the image density tends to decrease.

  Therefore, in the developer for developing an electrostatic latent image of the present embodiment (hereinafter sometimes simply referred to as “developer”), the number average particle diameter that tends to be detached from the toner is 50 nm or more and 500 nm or less. The above-described problems are solved when a toner having a surface of the above-described external additive (hereinafter sometimes referred to as “large-diameter external additive”) is used. Specifically, particles are contained in the carrier coating layer, and convex portions resulting from the particles are formed on the carrier surface. And the number average height H of the said convex part from the surface of a coating layer shall be 1/2 or more and less than 1 of the number average particle diameter D of this particle | grain. The number average height H of the protrusions from the surface of the coating layer is equal to or greater than the number average particle diameter of the external additive.

  The state of the carrier and toner is shown in FIG. In FIG. 1, (A) shows the state of arrangement of the carrier and toner at the initial stage of printing, and (B) is sometimes expressed as “time of use” after the number of prints increases with time (hereinafter referred to as “usage over time”). ).

  As shown in FIG. 1A, in this embodiment, the carrier has a coating layer 11 on the surface of a nucleus (not shown), and the coating layer 11 includes particles 12. On the surface of the carrier, convex portions due to the particles 12 are formed. Thus, the particles 12 form a convex portion that protrudes from the surface S of the coating layer 11. The number average height H of the convex portions is ½ or more and less than 1 of the number average particle diameter D of the particles 12. When the number average height H of the protrusions is ½ or more of the number average particle diameter D of the particles 12, the angle θ formed by the surface S of the coating layer 11 and the surface of the particles 12 is 90 degrees or less. The external additive 14 detached from the toner is collected in this portion (the base portion of the particle 12). The number average height H of the protrusions is equal to or greater than the number average particle diameter of the external additive 14. Moreover, the above-mentioned “angle θ formed” means “the smaller of the angles between the surface S and the tangent at the contact point with the surface S when the particle 12 is approximated by a circle”.

  That is, in the initial stage of image output, as shown in FIG. 1A, the large-diameter external additive detached from the toner is collected at the base of the particle 12 on the surface S of the coating layer 11. In addition, a decrease in image density due to the external additive 14 is suppressed.

  In addition, when the number of output sheets is increased by repeated development, a portion of the particles 12 that is 1/2 or more of the number average particle diameter D protrudes from the carrier surface, so that the particles 12 are easily detached from the coating layer 11. It has become. At this time, as shown in FIG. 1B, a recess is formed in the trace where the particles 12 are detached from the coating layer 11, and the external additive 14 detached from the toner is captured in the recess. When the external additive 14 is captured in the recess, the carrier coating layer 11 is prevented from being peeled off due to friction from the external additive 14, and the core of the carrier is exposed and the resistance value is reduced. As a result, an increase in image density is suppressed.

As described above, by using the carrier according to the present embodiment as the developer combined with the large-diameter external additive, the fluctuation of the image density can be suppressed from the initial use to the time of use.
Hereinafter, the toner and the carrier constituting the developer of the present embodiment will be described.

〔toner〕
The toner in the exemplary embodiment is not particularly limited as long as it has an external additive having a number average particle diameter of 50 nm or more and 500 nm or less on the surface.

-External additive-
The number average particle diameter of the external additive is in the range of 50 nm to 500 nm, preferably in the range of 75 nm to 300 nm, and more preferably in the range of 100 nm to 300 nm.
Since the external additive having a number average particle diameter of less than 50 nm is not easily detached from the toner, the problem of this embodiment that the image density is lowered due to the external additive adhering to the carrier surface hardly occurs. Therefore, in the present embodiment, a so-called small particle size external additive having a number average particle diameter of less than 50 nm may be used in combination, but at least one of the external additives has a number average particle diameter in the above range. Use things.

  In addition, the large-diameter external additive in the present embodiment is desirably externally added in the range of 0.3% by mass to 2.0% by mass with respect to the toner mass, and 0.5% by mass to 1.5% by mass. A range of less than or equal to mass% is more desirable, and a range of greater than or equal to 0.5 mass% and less than or equal to 1.2 mass% is even more desirable. When the amount of the large-diameter external additive is within the above range, frictional charging is promoted and the charging property is excellent.

  The number average particle size of the external additives having a small particle size that can be used in combination is preferably in the range of 10 nm or more and less than 50 nm, and more preferably in the range of 20 nm or more and less than 50 nm. By using an external additive having a small particle size, the fluidity of the toner is excellent.

  The small-diameter external additive is preferably used in the range of 0.5% by mass or more and 3.0% by mass or less, and in the range of 0.8% by mass or more and 2.0% by mass or less, based on the mass of the toner. It is more desirable to do.

  Here, the number average particle diameter of the external additive is measured using a laser diffraction / scattering particle size distribution measuring apparatus (HORIBA LA-910). In addition, an external additive to be measured was added to an aqueous solution containing 0.1% by mass of sodium polyphosphate in an aqueous solution of 0.5% by mass of an anionic surfactant (Newlex Paste H, manufactured by NOF Corporation). A sample obtained by dispersing this with an ultrasonic wave for 1 minute is used as a measurement sample. Moreover, when analyzing from a developing agent, it measures by the method similar to the measurement of the number average particle diameter D of the particle | grains 12 mentioned later.

In the present embodiment, the external additives include SiO ₂ , TiO ₂ , Al ₂ O ₃ , CuO, ZnO, SnO ₂ , CeO ₂ , Fe ₂ O ₃ , MgO, BaO, CaO, K ₂ O, Na ₂ O. , ZrO ₂ , CaO · SiO ₂ , K ₂ O · (TiO ₂ ) _n , Al ₂ O ₃ · 2SiO ₂ , CaCO ₃ , MgCO ₃ , BaSO ₄ , MgSO _{4 and the} like. Of these, silica particles and titania particles are desirable from the viewpoint of good toner fluidity.
Also, resin particles such as polystyrene particles, polymethyl methacrylate particles, and polyvinylidene fluoride particles, and cleaning or transfer aids such as cerium oxide and zinc stearate may be used.

It is desirable that the surface of the inorganic particles as the external additive is previously hydrophobized. This hydrophobization treatment improves the powder flowability of the toner, and is effective for the environmental dependency of charging and the resistance to carrier contamination. The hydrophobic treatment is performed by immersing inorganic particles in the hydrophobic treatment agent.
The hydrophobizing agent is not particularly limited, and examples thereof include silane coupling agents, silicone oils, titanate coupling agents, aluminum coupling agents and the like. These may be used individually by 1 type and may use 2 or more types together. Of these, silane coupling agents are desirable.

As the silane coupling agent, for example, any of chlorosilane, alkoxysilane, silazane, and a special silylating agent can be used. Specifically, methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, phenyltrichlorosilane, diphenyldichlorosilane, tetramethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, tetraethoxysilane, Methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, diphenyldiethoxysilane, isobutyltriethoxysilane, decyltrimethoxysilane, hexamethyldisilazane, N, O- (bistrimethylsilyl) acetamide, N, N- ( Trimethylsilyl) urea, tert-butyldimethylchlorosilane, vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane , Γ-methacryloxypyrroletrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-mercapto Examples thereof include propyltrimethoxysilane and γ-chloropropyltrimethoxysilane.
The amount of the hydrophobizing agent used varies depending on the type of inorganic particles and is not unconditionally defined, but is usually in the range of 5 to 50 parts by mass with respect to 100 parts by mass of the inorganic particles.

Further, the degree of hydrophobicity of the external additive by the hydrophobizing agent is preferably 40% or more and 100% or less, more preferably 50% or more and 90% or less, and still more preferably 60% or more and 90% or less.
The degree of hydrophobicity in this embodiment is as follows when 0.2 g of particles is added to 50 cc of water, stirred with a stirrer, titrated with methanol, and the methanol titration when all particles are suspended in a solvent is Tcc. It is defined as the degree of hydrophobicity (M) represented by the formula:
Hydrophobicity (M) = [T / (50 + T)] × 100 (vol.%)

The toner according to the exemplary embodiment includes a binder resin and a colorant, and the external additive described above is externally added to toner particles containing a release agent and other components as necessary.
Hereinafter, the components of the toner particles will be described in detail.

-Binder resin-
As the binder resin used for the toner particles, a known resin is used, and a crystalline resin is used or a crystalline resin and an amorphous resin are used in combination because excellent low-temperature fixability is obtained. May be.

  Binder resins include styrenes such as styrene and chlorostyrene; monoolefins such as ethylene, propylene, butylene and isoprene; vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzoate and vinyl butyrate; methyl acrylate , Α-methylene aliphatic monocarboxylic acid esters such as ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, dodecyl methacrylate; vinyl Examples thereof include homopolymers and copolymers such as vinyl ethers such as methyl ether, vinyl ethyl ether, and vinyl butyl ether; vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, and vinyl isopropenyl ketone;

Typical binder resins include polystyrene, styrene-alkyl acrylate copolymer, styrene-alkyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer. Examples thereof include coalescence, polyethylene, and polypropylene. Furthermore, polyester, polyurethane, epoxy resin, silicone resin, polyamide, modified rosin, paraffin wax and the like can be mentioned.
Of these, styrene-alkyl acrylate copolymers and styrene-alkyl methacrylate copolymers are particularly desirable.

  Specific examples of the crystalline resin include long-chain alkyl dicarboxylic acids such as adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, tridecanedioic acid, butanediol, pentanediol, Polyester resins using long-chain alkyl or alkenyl diols such as hexanediol, heptanediol, octanediol, nonanediol, decanediol, and batyl alcohol; amyl (meth) acrylate, hexyl (meth) acrylate, (meth) Heptyl acrylate, octyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, undecyl (meth) acrylate, tridecyl (meth) acrylate, myristyl (meth) acrylate, (meth) acrylic Cetyl acid, (meth) acrylic acid ester And vinyl resins using long-chain alkyls such as ryl, oleyl (meth) acrylate, and behenyl (meth) acrylate, and (meth) acrylic esters of alkenyl; to recording media such as paper at the time of fixing. From the viewpoints of adhesiveness, chargeability, and easy adjustment of the melting point within a desired range, a polyester resin based crystalline resin is desirable.

-Colorant-
The colorant constituting the toner particles is not particularly limited and may be either a dye or a pigment, but a pigment is desirable from the viewpoint of light resistance and water resistance.
The pigments include carbon black, aniline black, aniline blue, calcoil blue, chrome yellow, ultramarine blue, dupont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green oxalate, lamp black, rose bengal and quinacridone. Benzidine Yellow, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 185, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 180, C.I. I. Pigment yellow 97, C.I. I. Pigment yellow 74, C.I. I. Pigment blue 15: 1, C.I. I. A known pigment such as CI Pigment Blue 15: 3 is used.

  Moreover, you may use magnetic powder as a coloring agent. As the magnetic powder, a known magnetic material such as a ferromagnetic metal such as cobalt, iron or nickel, or an alloy or oxide of a metal such as cobalt, iron, nickel, aluminum, lead, magnesium, zinc or manganese is used.

  The above colorants may be used alone or in combination of two or more. In addition, each color toner such as yellow toner, magenta toner, cyan toner, and black toner can be obtained by appropriately selecting the type of the colorant.

  The content of the colorant contained in the toner in the exemplary embodiment is preferably 0.1 parts by weight or more and 40 parts by weight or less, more preferably 1 part by weight or more and 30 parts by weight or less with respect to 100 parts by weight of the toner particles. .

-Other internal components-
Other components such as a release agent and a charge control agent may be internally added to the toner in the exemplary embodiment as necessary.
A mold release agent is generally used for the purpose of improving mold release properties. Specific examples of the release agent include low molecular weight polyolefins such as polyethylene, polypropylene, and polybutene; silicones having a melting temperature; fatty acid amides such as oleic acid amide, erucic acid amide, ricinoleic acid amide, and stearic acid amide; Plant waxes such as uba wax, rice wax, candelilla wax, tree wax, jojoba oil; animal waxes such as beeswax; minerals and petroleum such as montan wax, ozokerite, ceresin, paraffin wax, microcrystalline wax, Fischer-Tropsch wax Waxes; ester waxes such as fatty acid esters, montanic acid esters, and carboxylic acid esters. These release agents may be used alone or in combination of two or more.

  The content of the release agent is preferably 1 part by mass or more and 20 parts by mass or less, and more preferably 2 parts by mass or more and 15 parts by mass or less with respect to 100 parts by mass of the toner particles. When the content of the release agent is within the above range, the effect of adding the release agent is exhibited, and a decrease in chargeability is suppressed.

  The melting point of the release agent is preferably 50 ° C. or higher and 120 ° C. or lower, and more preferably 60 ° C. or higher and 100 ° C. or lower. When the melting point of the release agent is within the above range, the blocking resistance and developability are excellent.

  In addition, a charge control agent may be added to the toner (toner particles) as necessary. Known charge control agents are used, for example, azo metal complex compounds, metal complex compounds of salicylic acid, and resin type charge control agents containing polar groups.

-Toner production method-
For the production of the toner, a known wet method or a dry method is used. For example, a kneading and pulverizing method in which a binder resin, a colorant, and a release agent, a charge control agent, and the like are kneaded, pulverized, and classified as necessary. A method of changing the shape of the particles obtained by the kneading and pulverization method by mechanical impact force or thermal energy; emulsion polymerization of a polymerizable monomer of a binder resin, and formation of a dispersion and a colorant Emulsion polymerization aggregation method for obtaining a toner by mixing a dispersion liquid and a dispersion liquid of a release agent, a charge control agent, etc., which are used as necessary, and aggregating and heat-fusing to obtain a toner; binder resin A suspension polymerization method in which a polymerizable monomer for obtaining a colorant and, if necessary, a solution of a release agent, a charge control agent, etc. are suspended in an aqueous solvent for polymerization; a binder resin; Suspending in a water-based solvent and granulating a colorant and, if necessary, a solution such as a release agent and a charge control agent. Law; and the like are used.
Alternatively, the toner obtained by the above method may be used as core particles, and resin particles may be further adhered, followed by heat fusion to produce a toner having a core-shell structure.

Subsequently, an external additive (large-diameter external additive) having a number average particle size of 50 nm to 500 nm and, if necessary, a small-diameter external additive are added to the toner particles thus obtained and mixed. Thus, the toner in this embodiment is obtained.
The mixing of the toner particles and the external additive is performed by a known method, for example, a V blender, a Henshur mixer, a Ladyge mixer or the like.
Furthermore, if necessary, coarse particles in the obtained toner may be removed using a vibration sieving machine, a wind sieving machine, or the like.

-Toner particle size-
The volume average particle diameter of the toner obtained as described above is preferably in the range of 2 μm to 8 μm, and more preferably in the range of 4 μm to 7 μm. When the particle size of the toner is within the above range, the chargeability and fluidity are excellent.

  The volume average particle size distribution index (GSDv), which is an index of particle size distribution, is preferably 1.6 or less, and more preferably 1.5 or less. When the particle size distribution is within the above range, generation of reverse polarity toner and low-charge toner can be suppressed.

For the toner volume average particle size (cumulative volume average particle size D _50v ), number average particle size (cumulative number average particle size D _50P ) and various particle size distribution indices, Coulter Multisizer II (manufactured by Beckman-Coulter) is used. The electrolyte solution is measured using ISOTON-II (manufactured by Beckman Coulter).
In the measurement, a measurement sample is added in a range of 0.5 mg to 50 mg as a dispersant in 2 ml of a 5% by mass aqueous solution of a surfactant (desirably sodium alkylbenzenesulfonate). This is added to an electrolytic solution of 100 ml to 150 ml.
The electrolyte in which the sample is suspended is dispersed for about 1 minute with an ultrasonic disperser, and the particle size distribution of particles having a particle size in the range of 2 μm to 60 μm using a Coulter Multisizer II with an aperture of 100 μm. Measure. The number of particles to be sampled is 50,000.

For the particle size range (channel) divided on the basis of the particle size distribution measured in this way, the cumulative distribution is drawn from the small diameter side for each volume and number, and the cumulative particle size average particle diameter is 16%. Diameter D _16v , cumulative number average particle diameter D _16P , cumulative volume average particle diameter D _50v , cumulative volume average particle diameter D _50P , cumulative number average particle diameter D _50P , cumulative volume average particle diameter D _84v , the cumulative number average particle diameter D _84P .
Using these, the volume average particle size distribution index (GSDv) is calculated as (D _84v / D _16V ) ^1/2 , and the number average particle size distribution index (GSDp) is calculated as (D _84P / D _16P ) ^1/2 .

[Carrier]
Next, the carrier according to the present embodiment will be described with reference to FIG.
The carrier according to the present embodiment includes a core body 16 and a coating layer 11 that covers the core body 16. The coating layer 11 contains particles 12, and convex portions due to the particles 12 are formed on the carrier surface. And the number average height H of the said convex part from the surface of the coating layer 11 is 1/2 or more and less than 1 of the number average particle diameter D of the particle | grains 12, and the number average height H of this convex part is the said It is not less than the number average particle diameter of the external additive 14 of the toner.

  In the initial stage of image output, the external additive 14 of the toner is captured at the contact portion (base portion) of the particles 12 to the coating layer 11, and the particles 12 are detached over time when the number of output sheets increases. The external additive 14 is trapped in the trace recess.

  From the viewpoint of achieving the above action, the number average height H of the protrusions from the surface of the coating layer 11 is 1/2 or more and less than 1 of the number average particle diameter D of the particles 12, and is 1/2 or more and 4/5 or less. It is desirable that it is 3/5 or more and 4/5 or less.

  In addition, since the external additive of the toner is captured at the contact portion (base portion) of the particles 12 to the coating layer 11, the number average height H of the convex portions from the surface of the coating layer 11 is the external additive 14. More than the number average particle diameter. Desirably, the number average height H is more than twice the number average particle diameter of the external additive 14, and more preferably more than four times.

The number average height H of the convex portions from the surface of the coating layer 11 is measured by the following method.
30 parts by weight of a carrier is added to 70 parts by weight of a mixed liquid of two-part adhesive quick 30 (manufactured by Konishi Co., Ltd.), mixed, and left to stand for 48 hours in a 25 ° C. environment to be cured. After shaping the cured product with a razor, it is cut with an ultramicrotome apparatus (LEICA, URUTRACUT UCT) equipped with a diamond knife SK2035 (manufactured by Sumitomo Electric Industries, Ltd.). Further, while confirming the smoothness of the cut surface with an optical microscope, cutting is performed until a smooth cut surface is formed, thereby producing a sample piece.
A cross-sectional image of the sample piece is obtained by observing the obtained sample piece with a scanning electron microscope. Since the obtained image is analyzed by WinROOF (manufactured by Mitani Corporation) as image analysis software, the number average height H of the particles 12 protruding from the coating layer 11 is calculated.
The average value of the number average height H of the protrusions is measured at five measurement points for one carrier, and is the arithmetic average of 50 randomly selected carriers.

  The number average height H of the protrusions correlates with the difference between the number average particle diameter D of the particles 12 and the thickness of the coating layer 11. Therefore, the number average height H of the convex portions is adjusted by the number product average particle diameter D of the particles 12 and the thickness of the coating layer 11. Also, using a spray method in which a coating solution containing a resin for forming a coating layer is sprayed on the surface of the suspended core, first a solution in which only the resin is dissolved is sprayed, and then the resin and particles 12 are dissolved. The number average height H of the protrusions is also adjusted by spraying the solution.

The number average particle diameter of the particles 12 is desirably 0.5 μm or more and 5 μm or less, more desirably 0.5 μm or more and 4 μm or less, and further desirably 0.6 μm or more and 3 μm or less.
When the number average particle diameter of the particles 12 is in the above range, the number average height H of the protrusions is high enough to capture the external additive 14, and the particles 12 are detached from the carrier over time. The size of the recesses formed sometimes collects an appropriate amount of the external additive, and as a result, image fluctuation due to use over time can be suppressed.

  The number average particle diameter D of the particles 12 is calculated by performing image analysis on a sample piece prepared by the same method as the method for measuring the number average height H of the protrusions described above. The average value of the average particle diameter D of the particles 12 is an arithmetic average of 50 randomly selected carriers.

The occupation ratio of the protrusions on the carrier surface is preferably in the following range. That is, the total length of the arc L _n (n indicates the number of particles 12 in the carrier cross section) where the outer peripheral portion of the coating layer and the particles 12 intersect with respect to the outer peripheral length L of the coating layer 11 in the cross section of the carrier ( L ₁ + L ₂ +... + L _n-1 + L _n ) is preferably 20% to 70%, more preferably 30% to 70%, and more preferably 30% to 60%. Is more desirably 30% or more and 50% or less.

  When the occupancy ratio of the convex portion is within the above range, the external additive 14 is sufficiently captured at the base of the convex portion in the initial stage of use, and the particle 12 is detached from the carrier by use over time, and the concave portion is formed in an appropriate amount. As a result, an appropriate amount of the external additive is collected, and as a result, image fluctuation is suppressed from the initial use to the use time.

  The outer peripheral length L of the coating layer 11 is the outer peripheral length when the particles 12 are not present on the surface of the coating layer of the carrier.

The outer peripheral length L of the covering layer 11 in the cross section of the carrier and the total length of the arc Ln where the outer peripheral portion of the covering layer and the particles 12 intersect are measured by the following method.
First, the total length of the arc Ln is calculated using a cross-sectional image obtained by the same method as the method for measuring the number average height H of the protrusions described above. The location where the recess in the cross section of the coating layer 11 exists is calculated as the length obtained by replacing both ends outside the recess with straight lines. The above value is the arithmetic average of 100 randomly selected carriers.
Below, the material which comprises a carrier is demonstrated.

-Nucleus-
There are no particular restrictions on the material of the carrier core 16, and examples include those in which magnetic powder is used alone as a core material, or those in which magnetic powder is finely divided and dispersed in a resin.
The magnetic powder material includes magnetic metals such as iron, nickel and cobalt, alloys of these with manganese, chromium and rare earth elements (for example, nickel-iron alloys, cobalt-iron alloys, aluminum-iron alloys), and Examples thereof include magnetic oxides such as ferrite and magnetite. Among these, magnetite is preferable because it has stable characteristics and is less toxic.

  The magnetic powder is made into fine particles and dispersed in the resin. The resin and magnetic powder are kneaded and pulverized, the resin and magnetic powder are melted and spray dried, and the polymerization method is used to contain the magnetic powder in the solution. Examples include a method of polymerizing a resin. The carrier preferably contains fine magnetic powder in an amount of 80% by mass or more based on the total mass of the carrier from the viewpoint of making it difficult for carrier scattering.

  The volume average particle diameter of the core 16 is generally 10 μm or more and 100 μm or less, and preferably 25 μm or more and 80 μm or less. The measurement of the volume average particle diameter of the core body 16 is performed in the same manner as the measurement of the volume average particle diameter of the carrier described later. In addition, when measuring a volume average particle diameter from a carrier, it measures after removing a coating layer.

As the carrier core, one having a volume electric resistance of 1 × 10 ⁷ Ωcm or more is desirable. A method for measuring the volume electric resistance will be described later.

Furthermore, for the purpose of low stress properties, a spherical nucleus produced by a polymerization method may be used. The true specific gravity of the polymerization nucleus is preferably 3.0 g / cm ³ or more and 5.0 g / cm ³ or less, and the saturation magnetization is preferably 40 emu / g or more.

  The sphericity of the carrier core 16 is not particularly limited. However, the decrease in image density due to adhesion of the external additive to the carrier, which is a problem of the present embodiment, occurs when the large-diameter external additive is released from the toner and migrates to the carrier surface. It is likely to happen in a high career. Therefore, it is a carrier having a high sphericity that effectively exhibits the effect of the present embodiment. Therefore, the effect of this embodiment is effectively achieved when a nuclei having a sphericity of 0.95 or more is used, and more effective is the use of a nuclei having a sphericity of 0.97 or more. This is the case.

In the present embodiment, the sphericity of the carrier means an average circularity measured by the following method.
0.2 g of carrier is dispersed in a 25% by mass aqueous solution of ethylene glycol, and this is used as a measurement sample. Using FPIA3000 (manufactured by Sysmex Corporation) as a measuring device, measurement is performed in the LPF measurement mode, particles having a particle size of less than 10 μm and more than 50 μm are cut and analyzed, 100 particles are measured, and the average circularity is measured. Ask. Here, each circularity is calculated | required based on following formula (1).

Formula (1): Circularity = equivalent circle circumference length / perimeter length = [2 × (A × π) ^1/2 ] / PM

  In the above formula (1), A represents the projected area of the carrier particles, and PM represents the perimeter of the carrier particles.

  The measurement is performed in the HPF mode (high resolution mode) and the dilution factor of 10 times. In the data analysis, the number particle size analysis range is 3 μm to 80 μm and the circularity analysis range is 0.850 to 1.000 for the purpose of eliminating measurement noise.

-Coating layer-
The carrier according to the present embodiment has a coating layer 11 that covers the core 16 described above.
As the coating layer 11, a known resin may be used as long as it is used as a material for a carrier coating layer, and two or more kinds of resins may be blended and used.
The resin constituting the coating layer is roughly classified into a resin for imparting chargeability to the toner (a charge imparting resin) and a resin having a low surface energy used for preventing the toner component from being transferred to the carrier. Can be mentioned.

Here, examples of the charge imparting resin for imparting negative chargeability to the toner include amino resins such as urea-formaldehyde resin, melamine resin, benzoguanamine resin, urea resin, polyamide resin, and epoxy resin. Furthermore, polystyrene resins such as polyvinyl and polyvinylidene resins, acrylic resins, polymethyl methacrylate resins, styrene acrylic copolymer resins, polyacrylonitrile resins, polyvinyl acetate resins, polyvinyl acetate resins, polyvinyl alcohol resins, polyvinyl butyral resins, ethyl cellulose resins And the like.
Examples of the charge imparting resin for imparting positive chargeability to the toner include polystyrene resins, halogenated olefin resins such as polyvinyl chloride, polyester resins such as polyethylene terephthalate resins and polybutylene terephthalate resins, and polycarbonate resins. Can be mentioned.

  Examples of the resin having a low surface energy used for preventing the transfer of the toner component to the carrier include polyethylene resin, polyvinyl fluoride resin, polyvinylidene fluoride resin, polytrifluoroethylene resin, polyhexafluoropropylene resin, fluororesin. Fluoroterpolymers such as copolymers of vinylidene fluoride and acrylic monomers, copolymers of vinylidene fluoride and vinyl fluoride, terpolymers of tetrafluoroethylene, vinylidene fluoride and non-fluorinated monomers, And silicone resin.

Among the resins having a low surface energy, a silicone resin is preferable, and polymethylsiloxane is preferable.
The use of polymethylsiloxane for the coating layer 11 not only makes it difficult to peel off the carrier surface due to stress in the carrier caused by stirring or the like, but also has high wear resistance and low surface energy. A surface that is not easily affected by the toner and external additives is obtained.

The average film thickness of the coating layer 11 is desirably 0.1 μm or more and 5 μm or less, more desirably 0.25 μm or more and 3.0 μm or less, and further desirably 0.25 μm or more and 2.0 μm or less. .
When the average film thickness of the coating layer 11 is in the above range, a concave portion of a trace from which particles 12 to be described later are detached is formed, and the external additive 14 is sufficiently supplemented. Excellent in terms of uniformity and prevention of peeling.

  The average film thickness of the coating layer 11 is the average value when 50 randomly selected carriers are measured using a cross-sectional image obtained by the same method as the method for measuring the number average height H of the protrusions described above. Calculate to find.

-Particles-
The carrier according to the present embodiment contains particles 12 in the coating layer 11. The material and shape of the particles 12 are not particularly limited as long as they satisfy the above relationship with the particle diameter of the external additive.

The material of the particles 12 is preferably semiconductive particles or conductive particles. “Semiconductive” means a volume resistivity of 10 ⁷ Ωcm or more and 10 ¹³ Ωcm or less, and “conductivity” means a volume resistivity of less than 10 ⁷ Ωcm.
Specific examples include metal powder, tin oxide, carbon black, titanium oxide, tin oxide, zinc oxide, barium sulfate, thermoplastic resin, thermosetting resin, etc., selected from tin oxide, titanium, and copper. At least one kind of particles is desirable from the viewpoint of suppressing fluctuations in image density over time.

  Examples of the thermoplastic resin used for the particles 12 include polyolefin resins, such as polyethylene, polypropylene; polyvinyl and polyvinylidene resins, such as polystyrene, acrylic resin, 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 comprising organosiloxane bond or a modified product thereof; fluororesin such as polytetrafluoroethylene, polyfluoride And vinyl chloride, polyvinylidene fluoride, polychlorotrifluoroethylene; polyester; polycarbonate and the like.

  Examples of the thermosetting resin used for the particles 12 include phenol resin; amino resin such as urea-formaldehyde resin, melamine resin, benzoguanamine resin, urea resin, polyamide resin; epoxy resin and the like.

  The content of the particles 12 in the coating layer 11 is such that the outer peripheral portion of the coating layer and the particles 12 intersect with the occupation ratio of the protrusions on the carrier surface, that is, the outer peripheral length L of the coating layer 11 in the cross section of the carrier. It is desirable to adjust so that the total length of the arc Ln is 20% or more and 70% or less. Specifically, the content of the particles in the coating layer 11 is preferably 30% by mass or more and 60% by mass or less, and more preferably 3% by mass or more and 20% by mass or less.

In addition, since the number average height H of the convex portions formed by the particles 12 contained in the coating layer 11 is 1/2 or more of the number average particle diameter D of the particles 12 and less than 1, the particles 12 It is designed so that a part of itself is embedded in the coating layer 11 in the initial stage of use and is easily detached from the coating layer 11 over time of use.
Since the carrier surface having such a structure can suppress fluctuations in image density over the period of use from the beginning of use due to the above action, the type of resin forming the coating layer 11 and the material of the particles 12 are not particularly limited. Absent.

  It is also effective to perform a post-treatment step after forming the coating layer 11 or to subject the particles 12 to a surface treatment so that the particles 12 are detached from the coating layer 11 over time of use.

-Carrier manufacturing method-
The method for forming the coating layer 11 on the carrier core 16 is not particularly limited, and a conventionally known method is used, and the following method is desirable.
That is, a coating layer forming solution (a solution containing a resin and particles 12 for forming a coating layer in a solvent, and optionally containing a charge control agent and the like) is prepared, and the coating layer forming solution Immersion method for immersing the core body, spray method for spraying the coating layer forming solution onto the surface of the core body 16, fluidized bed method for spraying the coating layer forming solution in a state where the core body 16 is suspended by flowing air, a kneader The kneader coater method etc. which mix the nucleus 16 and the solution for coating layer formation in a coater, and remove a solvent then are mentioned. However, it is not limited to the one using a solution. For example, depending on the type of the carrier core 16, a powder coating method in which the core 16 and the resin powder are heated and mixed together may be employed. Furthermore, after forming the coating layer, heat treatment may be performed by an apparatus such as an electric furnace or kiln.

  The solvent used in the coating layer forming solution for forming the coating layer 11 is not particularly limited as long as it dissolves the resin. For example, aromatic hydrocarbons such as xylene and toluene Ketones such as acetone and methyl ethyl ketone, ethers such as tetrahydrofuran and dioxane, and halides such as chloroform and carbon tetrachloride are used.

-Physical properties of carriers-
Carrier obtained as described above is more that magnetic force at the time of 1kOe it is preferably in the range of 170 emu / cm ³ or more 250 emu / cm ³ or less, a 185emu / cm ³ or more 235emu / cm ³ or less in the range desirable.
Here, the magnetic force of the carrier was measured by using a vibrating sample magnetometer BHV-525 (manufactured by Riken Electronics Co., Ltd.), taking a certain amount of sample for room temperature sample case powder for VSM (H-2902-151), And then measured in a magnetic field of 1 kOe.

The volume average particle diameter of the carrier is preferably in the range of 25 μm to 100 μm, more preferably in the range of 25 μm to 80 μm, and still more preferably in the range of 25 μm to 60 μm.
When the volume average particle diameter of the carrier is within the above range, the magnetic binding force to the developer holding member is exhibited, the adhesion of the carrier to the photoreceptor is suppressed, and the fine line reproducibility is excellent.

The volume average particle diameter of the carrier refers to a value measured using a laser diffraction / scattering particle size distribution analyzer (LS Particle Size Analyzer: LS13 320, manufactured by BECKMAN COULTER). For the particle size range (channel) obtained by dividing the obtained particle size distribution, by subtracting the volume cumulative distribution from the small particle size side, the particle size that becomes 50% cumulative with respect to the entire core is the volume average particle size D _50v . To do.

The density of the carrier in this embodiment is desirably 2.0 g / cm ³ or more and 5.0 g / cm ³ or less, more desirably 2.5 g / cm ³ or more and 4.5 g / cm ³ or less, More preferably, it is 3.0 g / cm ³ or more and 4.0 g / cm ³ or less. When the carrier density is in the above range, the charge imparting ability and fluidity are excellent.
Here, the carrier density is measured according to the method described in the density section of “Physical Chemistry Experiment Method (Tokyo Chemical Dojinsha, 3rd Edition)”. For the measurement, water having an electric resistance of 17 MΩ or more is used, and the measurement temperature is 25 ° C.

The volume electric resistance of the carrier in this embodiment is preferably controlled in the range of 1 × 10 ⁷ Ωcm to 1 × 10 ¹⁶ Ωcm, and is in the range of 1 × 10 ⁸ Ωcm to 1 × 10 ¹⁴ Ωcm. Is more desirably 1 × 10 ⁸ Ωcm or more and 1 × 10 ¹³ Ωcm or less.
When the volume electrical resistance of the carrier is within the above range, it functions as a developing electrode at the time of development and has excellent solid reproducibility. When the toner concentration in the developer is lowered, charge is injected from the developing roll to the carrier, and the carrier itself is Development is suppressed.

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

In the above formula (2), R is the volume electric resistance (Ω · cm) of the carrier, E is the applied voltage (V), I is the current value (A), I ₀ is the current value (A) at the applied voltage 0 V, L Represents the thickness (cm) of the carrier layer. A coefficient of 20 represents the area (cm ² ) of the electrode plate.

[Developer for developing electrostatic image]
The developer for developing an electrostatic charge image of the present embodiment contains the toner and the carrier. The developer according to this embodiment is prepared by mixing the carrier and toner according to this embodiment at an appropriate blending ratio. The carrier content ((carrier) / (carrier + toner) × 100) is preferably in the range of 85% by mass to 99% by mass, more preferably in the range of 87% by mass to 98% by mass, and still more preferably 89%. The range is from mass% to 97 mass%.

<Developer cartridge, process cartridge, image forming apparatus>
The image forming apparatus of the present embodiment exposes the electrostatic latent image holding member, a charging device that charges the electrostatic latent image holding member, and the charged electrostatic latent image holding member, An electrostatic latent image forming device for forming an electrostatic latent image on a holding member, a developing device for forming a toner image by developing with the electrostatic latent image developing developer of the present embodiment described above, and the toner image And a fixing device for fixing the transferred image transferred to the recording medium.

  Further, in the image forming apparatus of the present embodiment, for example, the part including the developing device may have a cartridge structure (developer cartridge, process cartridge) that can be attached to and detached from the image forming apparatus main body.

  Examples of the cartridge structure include a developer cartridge that is detachable from the image forming apparatus and stores the developer for developing an electrostatic image. Further, development that is detachable from the image forming apparatus and that develops a toner image by developing the electrostatic latent image formed on the surface of the electrostatic latent image holding member with at least the developer for developing an electrostatic latent image. An electrostatic latent image holding body, a charging device for charging the surface of the electrostatic latent image holding body, and an electrostatic latent image for forming an electrostatic latent image on the surface of the charged electrostatic latent image holding body And a process cartridge including at least one selected from the group consisting of a transfer device that transfers a toner image formed on the surface of the electrostatic latent image holding member to the surface of the transfer target.

  Hereinafter, although an example of the image forming apparatus of this embodiment is shown, it is not necessarily limited to this. In addition, the main part shown to a figure is demonstrated and the description is abbreviate | omitted about others.

  FIG. 3 is a schematic configuration diagram illustrating a four-tandem full-color image forming apparatus. The image forming apparatus shown in FIG. 3 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 apparatuses) are provided. These image forming units (hereinafter simply referred to as “units”) 10Y, 10M, 10C, and 10K are juxtaposed at a predetermined distance in the horizontal direction. The units 10Y, 10M, 10C, and 10K may be process cartridges that are detachable from the main body of 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 disposed 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. A force is applied to the support roller 24 in a direction 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 both. An intermediate transfer member cleaning device 30 is provided on the side surface of the electrostatic latent image holding member of the intermediate transfer belt 20 so as to face the driving roller 22.
Each of the developing devices 4Y, 4M, 4C, and 4K of the units 10Y, 10M, 10C, and 10K has four colors of yellow, magenta, cyan, and black accommodated in the toner cartridges 8Y, 8M, 8C, and 8K. Toner can be supplied.

  Since the first to fourth units 10Y, 10M, 10C, and 10K described above have the same configuration, here, the first unit 10Y that forms a yellow image disposed on the upstream side in the intermediate transfer belt traveling direction. Is 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 photoreceptor 1Y that acts as an electrostatic latent image holding body. Around the photoconductor 1Y, a charging roller (charging device) 2Y for charging the surface of the photoconductor 1Y to a predetermined potential, and the charged surface is exposed by a laser beam 3Y based on the color-separated image signal to electrostatically An exposure device (electrostatic latent image forming device) 3 for forming a latent image, a developing device (development image forming device) 4Y for supplying a developer to the electrostatic latent image to form a developed image, and intermediate transfer of the developed developed image A primary transfer roller 5Y (primary transfer device) for transferring onto the belt 20 and a photoconductor cleaning device 6Y having a cleaning blade for removing toner remaining on the surface of the photoconductor 1Y after the primary transfer are sequentially arranged. ing.
The primary transfer roller 5Y is disposed inside the intermediate transfer belt 20, and is provided at a position facing the photoreceptor 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).

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 photoreceptor 1Y is charged to a potential of about −600V to −800V by the charging roller 2Y.
The photoreceptor 1Y is formed by laminating a photosensitive layer on a conductive substrate (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 photoreceptor 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 photoreceptor 1Y, whereby an electrostatic charge image of a yellow print pattern is formed on the surface of the photoreceptor 1Y.

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

  In the developing device 4Y, for example, yellow toner having a volume average particle diameter of 7 μm including at least a yellow colorant, a crystalline resin, and an amorphous resin is accommodated. 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 charge on the photoreceptor 1Y, and a developer roll (developer holder). Is held on. As the surface of the photoreceptor 1Y passes through the developing device 4Y, the yellow toner is electrostatically attached to the latent image portion on the surface of the photoreceptor 1Y, and the latent image is developed with the yellow toner. . The photoreceptor 1Y on which the yellow developed image is formed continues to run at a predetermined speed, and the developed image developed on the photoreceptor 1Y is conveyed to a predetermined primary transfer position.

When the yellow developed image on the photoreceptor 1Y is conveyed to the primary transfer, a predetermined primary transfer bias is applied to the primary transfer roller 5Y, and the electrostatic force from the photoreceptor 1Y toward the primary transfer roller 5Y develops. The developed image on the photoreceptor 1Y is transferred onto the intermediate transfer belt 20 by acting on the image. 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 photoreceptor 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 to which the yellow developed image is transferred by the first unit 10Y is sequentially conveyed through the second to fourth units 10M, 10C, and 10K, and the developed images of the respective colors are superimposed and transferred in a multiple manner. .

  The intermediate transfer belt 20 on which the four color developed images are transferred in multiple numbers through the first to fourth units is disposed on the intermediate transfer belt 20, the support roller 24 in contact with the inner surface of the intermediate transfer belt 20, and the image holding surface side of the intermediate transfer belt 20. The secondary transfer roller (secondary transfer device) 26 is connected to a secondary transfer portion. 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 supplied 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 developed image, so The developed image is transferred onto the recording paper P. The secondary transfer bias at this time is determined according to the resistance detected by a resistance detection device (not shown) for detecting the resistance of the secondary transfer portion, and is voltage-controlled.

Thereafter, the recording paper P is fed into the fixing device 28, the developed image is heated, and the developed image having the superimposed color 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 developed image to the recording paper P via the intermediate transfer belt 20, but is not limited to this configuration, and the developed image is directly transferred from the photoreceptor. It may be a structure that is transferred to a recording sheet.

FIG. 4 is a schematic configuration diagram showing a preferred example of a process cartridge containing the electrostatic charge image developer of the present embodiment. The process cartridge 200 includes a photosensitive member (electrostatic latent image holding member) 107, a charging roller (charging device) 108, a developing device (developed image forming device) 111, a photosensitive member cleaning device 113 including a cleaning blade, and for exposure. The opening 118 and the opening 117 for static elimination exposure are combined and integrated using the mounting rail 116.
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. Reference numeral 300 denotes a recording paper (recording medium).

  The process cartridge shown in FIG. 4 includes a charging device 108, a developing device 111, a cleaning device 113, an opening 118 for exposure, and an opening 117 for static elimination exposure. It is possible to combine them. In the process cartridge of this embodiment, in addition to the photoconductor 107, the charging device 108, the developing device 111, the cleaning device 113, the opening 118 for exposure, and the opening 117 for static elimination exposure are configured. It comprises at least one selected from the group.

  Hereinafter, the present embodiment will be described by way of examples, but the present embodiment is not limited to these examples.

<Preparation of Toner (1)>
[Manufacture of toner particles]
-Preparation of resin particle dispersion-
・ Styrene (Wako Pure Chemical Industries, Ltd.) ... 320 parts by mass n-butyl acrylate (Wako Pure Chemical Industries, Ltd.) ... 80 parts by massβ-carboxyethyl acrylate (Rhodia Nikka) ... 9 parts by mass , 10-decanediol diacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.) ... 1.5 parts by mass Dodecanethiol (manufactured by Wako Pure Chemical Industries) ... 2.7 parts by mass

The above components are mixed and dissolved, dissolved in 550 parts by mass of ion-exchanged water containing 4 parts by mass of the anionic surfactant Dowfax (made by Dow Chemical Japan), and further dispersed and emulsified in a stirred tank. While slowly stirring and mixing for 10 minutes, 50 parts by mass of ion-exchanged water in which 6 parts by mass of ammonium persulfate was dissolved was added. Next, after sufficiently replacing nitrogen in the system, the stirring tank jacket was heated while stirring in the stirring tank until the temperature in the tank reached 70 ° C., and emulsion polymerization was continued for 5 hours.
As a result, a resin particle dispersion having a volume average particle size of 240 nm, a solid content of 42.9% by mass, an onset glass transition point of 50.6 ° C., Mw of 33900, and Mn of 10200 was obtained.

-Preparation of colorant particle dispersion-
-Magenta pigment (CI Pigment Red 122) ... 90 parts by mass-Anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd .: Neogen R) ... 10 parts by mass-Ion-exchanged water ... 240 parts by mass Part

  Each of the above components was mixed in a stirring tank and dispersed using an optimizer HJP-25008 (manufactured by Sugino Machine Co., Ltd.) set at a dispersion pressure of 245 MPa to prepare a colorant particle dispersion. The average particle diameter of the colorant in the colorant dispersion was 125 nm.

-Preparation of release agent dispersion-
・ Paraffin wax: 30 parts by mass (PolyWax850, manufactured by Toyo Petrolite Co., Ltd.)
・ Anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd .: Neogen R) ・ ・ ・ 2.5 parts by mass ・ Ion-exchanged water ・ ・ ・ 67.5 parts by mass

The above components were heated to 95 ° C. and dispersed using a homogenizer, and then dispersed with a dyno mill to obtain a wax dispersion (release agent dispersion). The average particle size of the dispersed wax was 240 nm.
Microtrac (manufactured by Nikkiso Co., Ltd., Microtrac UPA9340) was used for particle size measurement of these resin particle dispersion, colorant dispersion, and release agent dispersion.

-Production of toner particles-
(Aggregation process)
・ Ion-exchanged water ・ ・ 400 parts by mass ・ Resin particle dispersion ・ ・ ・ 240 parts by mass ・ Colorant dispersion ・ ・ ・ 64 parts by mass ・ Releasing agent dispersion ・ ・ ・ 56 parts by mass ・ Inorganic particle dispersion (Nissan Chemical Corporation, Snowtex OL) ... 12 parts by mass, inorganic particle dispersion (Nissan Chemicals, Snowtex OS) ... 10 parts by mass

  After mixing the above mixed components into a stirring vessel and thoroughly mixing and dispersing with a homogenizer, mixing of 0.5 parts by mass of a flocculant (manufactured by Asada Chemical Co., Ltd., polyaluminum chloride) and 100 parts by mass of ion-exchanged water The liquid was added over 10 minutes while stirring the stirring tank. After the addition, the liquid was gently heated to 40 ° C. and held for 30 minutes, and then heated to 49 ° C. After maintaining at 49 ° C. for 40 minutes, the particle diameter was measured with a Coulter counter (Multisizer II manufactured by Coulter Inc.), and it was confirmed that aggregated particles having a volume average particle diameter of 4.8 μm were formed. Further, the temperature of the heating jacket was raised and held at 52 ° C. for 40 minutes.

(Adhesion process)
To the dispersion containing aggregated particles prepared as described above, 65 parts by mass of the resin particle dispersion was gradually added, and the temperature of the heating jacket was further raised and maintained at 53 ° C. for 1 hour. With respect to the obtained adhered particles, the volume average particle diameter was measured to be 5.7 μm.

(Fusion process)
Next, a 1 mol / liter sodium hydroxide aqueous solution was added so that the pH was 6.0, and then the mixture was gently heated to 85 ° C. and kept for 60 minutes while continuing stirring. Thereafter, the mixture was heated to 96 ° C., a 1 mol / liter nitric acid aqueous solution was added until the pH reached 5.0, and the mixture was held for 5 hours.
Thereafter, the obtained toner slurry was cooled to 40 ° C., and the slurry was further subjected to sieving treatment with a mesh having a mesh size of 15 μm, followed by filtration with a filter press (manufactured by Tokyo Engineering Co., Ltd.).

With respect to 100 parts by mass of the obtained toner slurry, 500 parts by mass of ion-exchanged water (conductivity of 2 μS or less) is passed through the toner in the filter press apparatus, and subsequently 1 mol / liter of 300 parts by mass of ion-exchanged water is added. An acid washing water to which an aqueous nitric acid solution was added until pH 3.0 was passed, and further 400 parts by mass of ion-exchanged water was passed through. After pressing and dehydrating, a toner cake having a moisture content of 33.2% was obtained. The moisture content is based on the moisture amount, and measurement was performed at 150 ° C. for 20 minutes using MA30 manufactured by Sartorius.
This toner cake is crushed by Landel Mill RM-1 (manufactured by Deoksugaku Kosakusho) to obtain wet toner as a dry raw material, and this is dried using a flash jet dryer (manufactured by Seishin Enterprise) as an airflow dryer. To obtain magenta toner particles having a volume average particle diameter of 6.0 μm.

  To 100 parts by mass of the magenta toner particles, 1.50 parts by mass of rutile titanium oxide (treated with n-decyltrimethoxysilane, number average particle size 48 nm) as a small-diameter external additive, sol-gel as a large-diameter external additive. 1.70 parts by mass of silica (number average particle size 110 nm, sphericity 0.85) was added, blended for 15 minutes at a peripheral speed of 33 m / sec using a 5 liter Henschel mixer, and then sieved with a mesh opening of 45 μm. The toner (1) having the external additive was obtained by removing the coarse powder.

<Production of carrier (1)>
[Preparation of core particle (1)]
Into a Henschel mixer, 500 parts by weight of 0.3 μm spherical magnetite particles are added, and after sufficient stirring, 5.0 parts by weight of a titanate coupling agent is added, the temperature is raised to about 100 ° C., and the mixture is stirred well for 30 minutes. As a result, spherical magnetite particles coated with a titanate coupling agent were obtained.

  Next, in a 1 L four-necked flask, 60 parts by mass of phenol, 90 parts by mass of 37% by weight formalin, 500 parts by mass of the magnetite particles subjected to lipophilic treatment, 16 parts by mass of 28% by mass ammonia water, and 50 parts by mass of water. Parts were stirred and mixed. Next, it was raised to 85 ° C. over 60 minutes with stirring, and reacted at the same temperature for 180 minutes. Then, after cooling to 25 degreeC and adding 500 ml of water, the supernatant liquid was removed and the deposit was washed with water. This was dried at 130 ° C. under reduced pressure to obtain core particles (1) having a volume average particle diameter of 34.3 μm. The sphericity of the core particle (1) was 0.98.

[Preparation of coating layer forming raw material solution (a)]
Components of the following composition were stirred / dispersed with a stirrer for 60 minutes to prepare a coating layer forming raw material solution (a).

-Raw material solution for forming a coating layer (a)-
-Toluene: 95 parts by mass-Styrene-methacrylate copolymer (component ratio, 25:75) ... 15 parts by mass-Tin oxide (volume average particle diameter 1.1 µm) ... 2 parts by mass

  13 parts by mass of the obtained coating layer forming raw material solution (a) and 100 parts by mass of the core particles (1) were placed in a vacuum degassing kneader and stirred at 90 ° C. for 30 minutes, and then at −65 kPa for 5 minutes. After stirring at -70 kPa for 3 minutes, the pressure was further reduced to deaerate and dry.

After taking out the dried carrier, it was further cured at 150 ° C. for 1 hour in an electric furnace. After cooling, coarse powder due to aggregation was removed with a sieve having an opening of 75 μm to obtain a carrier (1) having a volume average particle diameter of 35.1 μm and a magnetic force of 1 emu / cm ³ at 201 emu / cm ³ .

[Measurement of coating layer thickness, number average height H of protrusions, and number average particle diameter D of particles]
When the cross section of the obtained carrier (1) was observed by the above-mentioned method, the average thickness of the coating layer was 0.27 μm, and the number average height H of the convex portions was 0.88 μm. The number average particle diameter D of the particles was 1.1 μm.

[Measurement of convexity ratio]
The cross section of the obtained carrier (1) was observed by the above-described method, and the total length of the arc where the outer peripheral portion of the coating layer and the particles contained in the coating layer intersect with respect to the outer peripheral length of the coating layer was calculated. 30%. In the following Tables 1 to 3, this value is described in the item of ΣL _n / L.

<Production of Carriers (2) to (15) and Comparative Carrier (1)>
In the production of the carrier (1), the number average particle diameter of tin oxide used in the coating layer was changed as shown in Table 1 below, and the addition amount of tin oxide and the resin amount were changed, Carriers (2) to (15) and comparative carrier (1) were prepared in the same manner except that the number average height H and the thickness of the coating layer were as shown in Table 1 below.

[Examples 1 to 15]
170 parts by mass of any one of the carriers (1) to (15) and 15 parts by mass of the toner (1) were stirred for 20 minutes at 40 rpm using a V blender, and sieved with a sieve having a 212 μm mesh. Electrostatic latent image developing developers (1) to (15) were prepared.

[Comparative Example 1]
A comparative magenta electrostatic latent image was prepared by stirring 170 parts by weight of the comparative carrier (1) and 15 parts by weight of the toner (1) at 40 rpm for 20 minutes using a V blender and sieving with a sieve having a mesh of 212 μm. A developing developer (1) was produced.

[Evaluation]
Using the electrostatic latent image developing developer (1), the DocuCentre Color 400 modified machine manufactured by Fuji Xerox Co., Ltd. has an image area of 80% at high temperature and high humidity (28 ° C. and 85% RH environment). 10,000 images were output continuously.
The image density at the 10th, 1000th, 5000th, and 10000th sheets of the output image was measured with an image densitometer (X-Rite 404A: manufactured by X-Rite). Further, the fluctuation of the density of the output image was evaluated according to the following criteria from the density difference between the 10th image and the 1000th image, 5000th image, and 10000th image.

-Evaluation criteria for fluctuations in image density-
◎: Density fluctuation of less than 3% ○: Density fluctuation of 3% or more and less than 6% Δ: Density fluctuation of 6% or more and less than 9% ×: Density fluctuation of 9% or more

The same evaluation was performed on the electrostatic latent image developing developers (2) to (15) and the comparative electrostatic latent image developing developer (1).
The results are shown in the table below.

As can be seen from the above table, the electrostatic latent image developing developers of Examples 1 to 15 were able to suppress fluctuations in image density even when the number of output images increased. In particular, when the number average height H of the projections is ½ or more and 4/5 or less of the number average particle diameter D of the particles, fluctuations in image density are suppressed, and more preferably 3/5 or more and 4 /. When it was 5 or less.
On the other hand, in Comparative Example 1 in which the number average height H of the convex portions is less than ½ of the number average particle diameter D of the particles, it is 10% with respect to the image density of the first 1000th sheet to the 10th sheet. The density was lowered, and the fluctuation of the image density was larger than in Examples 1 to 15.
In Examples 1, 4 to 7, the number average particle diameter D of the particles is 1.1 μm, and the number average height H of the protrusions is 4/5 of the number average particle diameter D of the particles. Examples 1, 5, and 6 in which the total length of the arc where the outer peripheral portion of the coating layer and the particles intersect with each other are 30% or more and 50% or less with respect to the outer peripheral length of the coating layer in the cross section of the carrier , 7, image density fluctuation was further suppressed.

[Examples 16 and 17]
<Preparation of Toner (2)>
1.50 mass of rutile type titanium oxide (treated with n-decyltrimethoxysilane, number average particle size 48 nm) as a small-diameter external additive with respect to the mass of the magenta toner particles used in the preparation of the toner (1). %, Silica prepared by a gas phase oxidation method as a large-diameter external additive (number average particle diameter 60 nm, sphericity 0.90) was added at 1.50 mass%, using a 5 liter Henschel mixer, peripheral speed 33 m / After blending for 15 minutes in seconds, the coarse powder was removed with a sieve having an opening of 45 μm to prepare toner (2) having an external additive.

<Preparation of Toner (3)>
1.50 mass of rutile type titanium oxide (treated with n-decyltrimethoxysilane, number average particle size 48 nm) as a small-diameter external additive with respect to the mass of the magenta toner particles used in the preparation of the toner (1). %, Polymethylmethacrylate particles (number average particle size 320 nm, sphericity 0.95) as a large-diameter external additive was added at 1.20% by mass, and blended for 15 minutes at a peripheral speed of 33 m / sec using a 5-liter Henschel mixer. Then, the coarse powder was removed with a sieve having an opening of 45 μm to prepare toner (3) having an external additive.

<Preparation of electrostatic latent image developing developer (16) (17)>
170 parts by mass of carrier (1) and 15 parts by mass of toner (2) or (3) were stirred for 20 minutes at 40 rpm using a V blender, and sieved with a sieve having a mesh of 212 μm, thereby electrostatic latent of magenta. Image developing developers (16) and (17) were prepared.

<Evaluation>
Evaluation was performed in the same manner as in Example 1, except that the developer (16) or (17) for developing an electrostatic latent image of magenta was used. The results are shown in the table below.

  As shown in the above table, even with the electrostatic latent image developing developers of Examples 16 and 17 in which the type and particle diameter of the external additive of the toner are changed, the image density changes even when the number of output images increases. Was suppressed.

[Examples 18 to 21]
Magenta electrostatic latent image developing developer (18) except that the tin oxide particles used in the coating layer forming raw material solution (a) of Example 1 were replaced with the following particles. ) To (21). Evaluation was performed in the same manner as in Example 1 using this developer. The results are shown in the table below.
Example 18: Alumina (trade name: AKP-3000, manufactured by Sumitomo Chemical Co., Ltd., number average particle size 0.62 μm)
Example 19: Silica (trade name: SFP-30M, manufactured by Denki Kagaku Kogyo Co., Ltd., number average particle size 0.7 μm),
Example 20: Titanium (trade name: TA-500, manufactured by Fuji Titanium Co., Ltd., number average particle diameter 0.68 μm)
Example 21: Copper (trade name: 1050Y, manufactured by Mitsui Mining & Smelting Co., Ltd., number average particle diameter of 0.75 μm)

  As shown in the above table, even with the electrostatic latent image developing developers of Examples 18 to 21 in which the type and particle diameter of the particles contained in the coating layer of the carrier were changed, even if the number of output images increased, the image The concentration fluctuation was suppressed. From the results of Example 1 and Examples 18 to 21, particularly when tin oxide particles, titanium particles, and copper particles were added to the coating layer, a decrease in image density at the initial use (1000th sheet) was suppressed. .

1Y, 1M, 1C, 1K, 107 photoconductor (image carrier)
2Y, 2M, 2C, 2K, 108 Charging roller 3Y, 3M, 3C, 3K Laser beam 3 Exposure device (electrostatic latent image forming device)
4Y, 4M, 4C, 4K, 111 Developing devices 5Y, 5M, 5C, 5K Primary transfer rollers 6Y, 6M, 6C, 6K, 113 Photoconductor cleaning devices 8Y, 8M, 8C, 8K Toner cartridges 10Y, 10M, 10C, 10K unit 11 carrier coating layer 12 particles 14 external additive 16 carrier core 20 intermediate transfer belt 22 drive roller 24 support roller 26 secondary transfer roller (transfer device)
28, 115 Fixing device 30 Intermediate transfer member cleaning device 107 Photoconductor 108 Charging device 111 Developing device 112 Transfer device 113 Cleaning device 115 Fixing device 116 Mounting rail 117 Opening portion 118 for static elimination exposure Opening portion 200 for exposure Process cartridge ,
P, 300 Recording paper (transfer object)

Claims (7)

A toner having a surface having an external additive having a number average particle diameter of 50 nm or more and 500 nm or less, and a carrier having a nucleus and a coating layer formed on the nucleus,
The coating layer includes particles;
Convex portions due to the particles are formed on the surface of the carrier, and the number average height H of the convex portions from the surface of the coating layer is not less than 1/2 and less than 1 of the number average particle diameter D of the particles. And a developer for developing an electrostatic latent image which is equal to or larger than the number average particle diameter of the external additive.   The development for electrostatic latent image development according to claim 1, wherein the number average height H of the protrusions from the surface of the coating layer is 3/5 or more and 4/5 or less of the number average particle diameter D of the particles. Agent.   The static length according to claim 1 or 2, wherein a total length of an arc where the outer peripheral portion of the coating layer and the particles intersect is 30% or more and 50% or less with respect to the outer peripheral length of the coating layer in a cross section of the carrier. Developer for developing an electrostatic latent image.   The developer for electrostatic latent image development according to any one of claims 1 to 3, wherein the particles include at least one selected from tin oxide, titanium, and copper.   5. A developer cartridge containing the developer for developing an electrostatic latent image according to claim 1. Development for developing a toner image by developing the electrostatic latent image formed on the surface of the electrostatic latent image holding member with the developer for developing an electrostatic latent image according to any one of claims 1 to 4. Equipment,
An electrostatic latent image holding body, a charging device for charging the surface of the electrostatic latent image holding body, an electrostatic latent image forming apparatus for forming an electrostatic latent image on the charged surface of the electrostatic latent image holding body, and the electrostatic At least one selected from the group consisting of transfer devices that transfer the toner image formed on the surface of the latent image carrier to the surface of the transfer target;
A process cartridge that is detachably attached to an image forming apparatus main body. An electrostatic latent image carrier;
A charging device for charging the electrostatic latent image holding member;
An electrostatic latent image forming apparatus that exposes the charged electrostatic latent image holding member to form an electrostatic latent image on the electrostatic latent image holding member;
A developing device that forms the toner image by developing the electrostatic latent image with the developer for developing an electrostatic latent image according to any one of claims 1 to 4.
A transfer device for transferring the toner image from the electrostatic latent image carrier to a recording medium;
A fixing device for fixing the transferred image transferred to the recording medium;
An image forming apparatus.