JP7163075B2 - Magnetic toner, image forming method, and magnetic toner manufacturing method - Google Patents

Description

The present invention relates to a magnetic toner used in recording methods using electrophotography, electrostatic recording, and toner jet recording, and an image forming method using the magnetic toner.

In recent years, there has been a demand for means for outputting images in a wide range of fields, from offices to homes, and one of them is demanding high durability that does not degrade image quality even when a large number of images are output in various usage environments. On the other hand, in addition to image quality, the image output device itself is required to be smaller and energy-saving.
As a means of miniaturization, it is effective to reduce the size of the cartridge containing the developer. , the contact development system is preferred. Therefore, the one-component contact development system is an effective means for satisfying the above performance.
However, the one-component contact development system is a development system in which a toner carrier and an electrostatic latent image carrier are arranged in contact (contact arrangement). That is, the toner is transported by rotating these carriers, and the contact portion receives a large share. Therefore, in order to obtain high-quality images, the toner must have high durability and high fluidity. necessary.
Toner with low fluidity stays in the carrier during development, is heated by rubbing, and tends to be fused. In particular, when the toner is fused in the toner carrier, "streaks" occur on the image.
On the other hand, a toner with low durability causes cracks and chips, contaminates the toner carrier and the electrostatic latent image carrier, and deteriorates the image quality. In addition, cracked or chipped toner is less likely to be charged, and may become a "fogging" component that is developed in a non-image area on the electrostatic latent image carrier.
Magnetic toner containing magnetic material (hereinafter also simply referred to as toner) has a large density difference between the resin and the magnetic material, and when an external force is applied, the force concentrates on the resin and displaces it, which cuts the resin. Cracking and chipping of the toner are likely to occur.
When it is desired to output a large number of images in various usage environments, a greater load is placed on the toner, and thus higher durability and higher fluidity are required.

Patent Document 1 proposes a toner containing a magnetic material.
Japanese Patent Application Laid-Open No. 2002-201000 proposes a magnetic toner in which a magnetic material is dispersed by using an aggregation method. This manufacturing method has an aggregating step of aggregating fine particles to a toner particle size and a coalescing step of melting the aggregates to coalesce and form a toner. With this method, the shape of the toner can be easily deformed, and the fluidity can be increased.

JP 2006-243593 A JP 2012-93752 A

The toner produced by the manufacturing method disclosed in Patent Document 1 has the problem that it is difficult to increase the degree of circularity, and the fusion of the toner tends to occur in a system such as a one-component contact development system that requires a share. ing. In addition, there are few locations in the toner where the binder resin is unevenly distributed like domains (hereinafter also referred to as domains of the binder resin), and the binder resin forms a fine network structure, so that the connections between the binder resins are reduced. become thinner. As a result, the binding force between the resins is lowered, and in a system where shear is applied, there is a problem that the force cannot be absorbed and the toner tends to deteriorate.
On the other hand, the toner disclosed in Patent Document 2, like the toner disclosed in Patent Document 1, has a structure in which there are few domains of the binder resin in the toner and the binding force between the resins is difficult to improve. As a result, there is a problem that a system that requires a share cannot absorb the force, and the toner tends to deteriorate.
Conversely, the toner in which the magnetic substance aggregates does not easily break the binder resin, but has a problem that the coloring power is lowered due to the decrease in the surface area of the magnetic substance, and the density of the output image is lowered.
Further, in the toner in which the magnetic material is aggregated, the content of the magnetic material tends to vary from toner particle to toner particle, and the magnetic material is particularly difficult to be introduced into the toner particles having a small particle size. As a result, when a large number of images are output, there is a problem that the density of the image gradually decreases.
The present invention provides a magnetic toner which is excellent in image quality, resistant to environmental changes, and excellent in stability in a system such as a one-component contact development system in which the toner has a strong share.

The present inventors have found that the problem can be solved by controlling the dispersion state of the magnetic material in the magnetic toner, and have completed the present invention.
That is, the present invention
A magnetic toner having emulsion-aggregated magnetic toner particles containing a binder resin, a wax , a magnetic substance , an aggregating agent and a chelating agent ,
Dn (μm) is the number average particle diameter of the magnetic toner,
CV1 (%) is the coefficient of variation of the luminance dispersion value in the particle size range of Dn−0.500 or more and Dn+0.500 or less of the magnetic toner,
When CV2 (%) is the variation coefficient of the brightness dispersion value in the particle size range of Dn-1.500 or more and Dn-0.500 or less of the magnetic toner,
The CV1 and the CV2 satisfy the relationship of the following formula (1),
the magnetic toner has an average brightness of 30.0 to 60.0 in a particle size range of Dn−0.500 to Dn+0.500;
In a cross section of the magnetic toner using a transmission electron microscope,
A variation coefficient CV3 of an area ratio occupied by the magnetic material is 40.0% or more and 80.0% or less when a cross section of the magnetic toner is divided by a square grid having a side of 0.8 μm. Magnetic toner.
CV2/CV1≤1.00 (1)

In addition, the present invention
a charging step of externally applying a voltage to the charging member to charge the electrostatic latent image carrier;
a latent image forming step of forming an electrostatic latent image on the charged electrostatic latent image carrier;
a developing step of developing the electrostatic latent image with toner carried on a toner carrier to form a toner image on the electrostatic latent image carrier;
a transfer step of transferring the toner image on the electrostatic latent image bearing member to a transfer material with or without an intermediate transfer member;
An image forming method including a fixing step of fixing a toner image transferred to a transfer material by heating and pressurizing means,
The developing step is a one-component contact development method in which the electrostatic latent image bearing member and the toner carried on the toner bearing member are brought into direct contact with each other for development,
The image forming method, wherein the toner is the toner of the present disclosure .
Furthermore, the present invention provides
preparing a resin particle dispersion in which resin particles are dispersed in an aqueous medium;
a step of preparing a wax dispersion in which wax is dispersed in an aqueous medium;
a step of preparing a magnetic substance dispersion in which a magnetic substance is dispersed in an aqueous medium;
a mixing step of mixing the resin particle dispersion, the wax dispersion and the magnetic substance dispersion;
After the mixing step, an aggregating step of aggregating the resin particles, the wax and the magnetic material to obtain aggregated particles, and
After the aggregation step, a coalescing step of heating the aggregated particles to unite the resin particles, the wax, and the magnetic material constituting the aggregated particles,
A method for producing a magnetic toner comprising
The aggregation step includes adding an aggregating agent to the mixed solution obtained in the mixing step to aggregate the resin particles, the wax and the magnetic material, and then adding a chelating agent to stop the aggregation and aggregate the particles. is a step of obtaining
A method for producing a magnetic toner, characterized in that the magnetic toner obtained is the magnetic toner of the present disclosure.

According to the present invention, it is possible to provide a magnetic toner which is excellent in image quality, resistant to environmental changes, and excellent in stability in a system in which the toner has a strong share, and an image forming method using the magnetic toner.

Schematic cross-sectional view of the developing device Schematic cross-sectional view of a one-component contact development type image forming apparatus An example showing the relationship between the particle size of toner and the coefficient of variation of the brightness dispersion value

In the present invention, unless otherwise specified, the descriptions of "○○ or more and XX or less" and "○○ to XX", which represent numerical ranges, mean numerical ranges including the lower and upper limits that are endpoints.
A monomeric unit also refers to the reacted form of the monomeric material in the polymer.
Hereinafter, the present invention will be described in more detail with reference to embodiments, but the present invention is not limited to these.

The magnetic toner of the present invention (hereinafter also simply referred to as toner)
A magnetic toner having magnetic toner particles containing a binder resin, wax and a magnetic substance,
Dn (μm) is the number average particle diameter of the magnetic toner,
CV1 (%) is the coefficient of variation of the luminance dispersion value in the particle size range of Dn−0.500 or more and Dn+0.500 or less of the magnetic toner,
When CV2 (%) is the variation coefficient of the luminance dispersion value in the particle size range of Dn-1.500 or more and Dn-0.500 or less of the magnetic toner, the CV1 and the CV2 are expressed by the following formula (1). satisfy relationships,
the magnetic toner has an average brightness of 30.0 to 60.0 in a particle size range of Dn−0.500 to Dn+0.500;
In a cross section of the magnetic toner using a transmission electron microscope,
A variation coefficient CV3 of an area ratio occupied by the magnetic material is 40.0% or more and 80.0% or less when a cross section of the magnetic toner is divided by a square grid having a side of 0.8 μm. . CV2/CV1≤1.00 (1)

In the magnetic toner, the variation coefficient of the average luminance and the luminance dispersion value at a specific particle size of the magnetic toner, and the dispersion state of the magnetic material in the magnetic toner particles (hereinafter also simply referred to as toner particles) are controlled.
In a system that has magnetic transport or a system that develops by controlling the chargeability and magnetic performance of the toner, the existence of toners with different magnetic substance contents causes different chargeability and magnetic performance,
Different toners may behave differently during development. As a result, an image defect such as a decrease in image density may occur. Therefore, in toner containing a magnetic material, it is generally important that the magnetic material is uniformly contained among toner particles.
Further, the brightness of the toner is an index representing the degree of light scattering of the toner, and the brightness of the toner decreases when a substance such as a coloring agent or a magnetic substance that absorbs light is contained.
On the other hand, the luminance dispersion value of toner is an index for seeing how much luminance varies in one toner particle in the measurement of luminance. Therefore, the coefficient of variation of the brightness variance value is an index of how much the brightness varies among toner particles.
The present inventors studied controlling the content of the magnetic substance between the magnetic toner particles, and set the luminance and the coefficient of variation of the luminance dispersion value to appropriate values. The inventors have found that the dispersibility becomes uniform, and that good images can be obtained without a decrease in density.

In a system such as a one-component contact development system that requires a high share, the binder resin forms a domain, and since it has a portion that does not contain any substance other than the resin, the domain absorbs the force applied to the toner. , thought to prevent cracking.
In other words, the present inventors have considered that having a portion where the binder resin is unevenly distributed in the toner particles, that is, having a domain of the binder resin is an effective means for solving cracking and chipping of the toner.
However, in a toner containing a magnetic material, it has been difficult to allow the magnetic material to be uniformly dispersed among the toner particles and to allow the domains of the binder resin to exist in each toner particle. However, we have found a way to make these compatible. As a result, it was possible to produce a toner in which the dispersibility of the magnetic material was uniform among the toner particles and the domains of the binder resin were present in each of the toner particles. The toner is resistant to cracking and chipping, and is capable of providing good images.

When the number average particle diameter of the magnetic toner is Dn (μm), the average brightness in the particle diameter range of Dn-0.500 to Dn+0.500 is 30.0 to 60.0. The average luminance is preferably 35.0 or more and 50.0 or less.
By controlling the average luminance within the above range, good colorability is exhibited, and a decrease in image density is suppressed even when images are reproduced continuously.
If the average luminance is less than 30.0, the content of the magnetic material is large, the toner tends to crack, and fogging occurs.
If the average luminance exceeds 60.0, the content of the magnetic material is small, the coloring power is lowered, and the image density is lowered at the initial stage of outputting a large number of images.
In order to control the average brightness within the above range, it is preferable to adjust the content of the magnetic material.
A method for measuring the average luminance will be described later.

CV1 (%) is the coefficient of variation of the luminance dispersion value in the particle size range of Dn−0.500 or more and Dn+0.500 or less of the magnetic toner,
When CV2 (%) is the variation coefficient of the luminance dispersion value in the particle size range of Dn-1.500 or more and Dn-0.500 or less of the magnetic toner,
The CV1 and the CV2 satisfy the relationship of the following formula (1).
CV2/CV1≤1.00 (1)
The CV2/CV1 is preferably 0.70 or more and 0.95 or less.
When CV2/CV1 is 1.00 or less, the content of the magnetic substance in the magnetic toner particles becomes less dependent on the particle size of the toner particles. As a result, uneven charging of toner particles and uneven magnetic properties are suppressed, and developability is improved even when a large number of images are output.
When CV2/CV1 exceeds 1.00, the content of the magnetic material in the magnetic toner particles depends on the particle size of the toner particles, making it difficult for small-diameter toner particles to contain the magnetic material. As a result, when a large number of images are output, toner particles with a high content of magnetic substances are selectively output in the first half of the output, so a large amount of toner particles with a low content of magnetic substances remain in the second half of the output. A decrease in concentration occurs.
As means for controlling CV2/CV1 within the above range, adjustment of the particle size of the magnetic material can be mentioned. In addition, it is preferable to produce toner particles by using a pulverization method, an emulsion aggregation method, or the like, in which the magnetic substance is easily incorporated into the small-diameter particles.
A method of measuring the luminance variance value and its coefficient of variation will be described later.

The CV1 is preferably 1.00% or more and 4.00% or less, more preferably 1.00% or more and 3.50% or less. CV1 has a lower limit of 1.00%.
When CV1 is within the above range, there is little difference in the state of existence of the magnetic material between the toner particles, the image density after continuous image formation is less likely to change, and good images can be obtained.
The CV1 can be adjusted by controlling the dispersion state of the magnetic material during the production of the toner particles.

In the cross section of the magnetic toner using a transmission electron microscope (TEM), the variation in the occupied area ratio of the magnetic material when the cross section of the magnetic toner is divided by a square grid with one side of 0.8 μm. The coefficient CV3 is 40.0% or more and 80.0% or less. The CV3 is preferably 50.0% or more and 70.0% or less.
The fact that the CV3 is within the above range means that the magnetic material is locally unevenly distributed in the magnetic toner particles. That is, by unevenly distributing the magnetic material in the magnetic toner particles, it is possible to appropriately provide a portion where the magnetic material does not exist (that is, the domain portion of the binder resin), and allow this portion to absorb the share from the outside. becomes possible. As a result, cracking of the toner is suppressed, and in a high market share system such as the one-component contact development method, there is no image deterioration such as a decrease in image density or development streaks when a large number of images are output, and fogging occurs. You can get a good image without it.

When the CV3 is less than 40.0%, the difference in the occupied area ratio of the magnetic material is small between the grids dividing the cross section of the magnetic toner, and the binder resin domain is not present, or This means that the abundance of domains in the binder resin is small.
In this case, most of the binder resin forms a fine network structure, and connections between the binder resins become thin. As a result, in a system such as a one-component contact development system in which the toner has a high share, the toner tends to crack, and fogging occurs due to charging failure.
On the other hand, when the CV3 exceeds 80.0%, the magnetic material is excessively localized in the toner. In this case, the magnetic substances agglomerate with each other, resulting in a decrease in coloring power due to a decrease in surface area, and a decrease in image density at the initial stage of image formation.
Examples of methods for adjusting the CV3 within the above range include controlling the hydrophilicity and hydrophobicity of the surface of the magnetic material, controlling the degree of aggregation of the magnetic material during the production of the toner particles, and the like.
For example, in the case of using an emulsion aggregation method, a method of preliminarily aggregating a magnetic substance and introducing it into the toner particles, or adding a chelating agent and/or adjusting the pH in the coalescence step may adjust the degree of agglomeration of the magnetic substance. methods of adjustment, and the like.

The magnetic toner is an average occupied area ratio of the magnetic material when the cross section of the magnetic toner is divided by a square grid with one side of 0.8 μm in the cross section of the magnetic toner using a transmission electron microscope (TEM). The value is preferably 10.0% or more and 40.0% or less, more preferably 15.0% or more and 30.0% or less.
When the average value of the occupied area ratio is within the above range, the state of dispersion of the magnetic material in the toner particles is appropriate, and a decrease in coloring power due to excessive aggregation can be suppressed.
In addition, the presence amount of the domains of the binder resin is appropriate, and cracking of the toner hardly occurs. As a result, fog is less likely to occur and good images can be obtained.
Methods for controlling the average value of the occupied area ratio of the magnetic substance within the above range include controlling the hydrophilicity and hydrophobicity of the surface of the magnetic substance, and controlling the degree of agglomeration of the magnetic substance during the production of the toner particles. etc.

The binder resin is not particularly limited, and known resins for toner can be used. Specific examples of binder resins include polyester resins, polyurethane resins, and vinyl resins.
Monomers that can be used in the production of vinyl resins include the following monomers.
Aliphatic vinyl hydrocarbons: alkenes such as ethylene, propylene, butene, isobutylene, pentene, heptene, diisobutylene, octene, dodecene, octadecene, α-olefins other than those mentioned above;
Alkadienes such as butadiene, isoprene, 1,4-pentadiene, 1,5-hexadiene and 1,7-octadiene.
Cycloaliphatic vinyl hydrocarbons: mono- or di-cycloalkenes and alkadienes, such as cyclohexene, cyclopentadiene, vinylcyclohexene, ethylidenebicycloheptene;
Terpenes such as pinene, limonene, indene.
Aromatic vinyl hydrocarbons: styrene and its hydrocarbyl (alkyl, cycloalkyl, aralkyl and/or alkenyl) substituted products such as α-methylstyrene, vinyltoluene, 2,4-dimethylstyrene, ethylstyrene, isopropylstyrene, butylstyrene, phenylstyrene, cyclohexylstyrene, benzylstyrene, crotylbenzene, divinylbenzene, divinyltoluene, divinylxylene, trivinylbenzene; and vinylnaphthalene.
Carboxy group-containing vinyl-based monomers and metal salts thereof: unsaturated monocarboxylic acids having 3 to 30 carbon atoms, unsaturated dicarboxylic acids, anhydrides thereof, and monoalkyl (1 to 27 carbon atoms) esters thereof. For example, acrylic acid, methacrylic acid, maleic acid, maleic anhydride, maleic acid monoalkyl ester, fumaric acid, fumaric acid monoalkyl ester, crotonic acid, itaconic acid, itaconic acid monoalkyl ester, itaconic acid glycol monoether, citraconic acid , citraconic acid monoalkyl esters, carboxy group-containing vinyl monomers of cinnamic acid.
vinyl esters such as vinyl acetate, vinyl propionate, vinyl butyrate, diallyl phthalate, diallyl adipate, isopropenyl acetate, vinyl methacrylate, methyl 4-vinyl benzoate, cyclohexyl methacrylate, benzyl methacrylate, phenyl acrylate, phenyl methacrylate, vinyl methoxy acetate, vinyl benzoate, ethyl α-ethoxy acrylate, alkyl acrylates and alkyl methacrylates (methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, Butyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, lauryl acrylate, lauryl methacrylate, myristyl acrylate, myristyl methacrylate, cetyl acrylate, cetyl methacrylate, stearyl acrylate, stearyl methacrylate, eicosyl acrylate, eicosyl methacrylate, behenyl acrylate , behenyl methacrylate, etc.), dialkyl fumarate (dialkyl fumarate, the two alkyl groups are linear, branched or alicyclic groups having 2 to 8 carbon atoms), dialkyl maleate ( Maleic acid dialkyl ester, two alkyl groups are linear, branched or alicyclic groups having 2 to 8 carbon atoms), vinyl monomers having a polyalkylene glycol chain (polyethylene glycol (molecular weight 300) Monoacrylate, polyethylene glycol (molecular weight 300) monomethacrylate, polypropylene glycol (molecular weight 500) monoacrylate, polypropylene glycol (molecular weight 500) monomethacrylate, methyl alcohol ethylene oxide (ethylene oxide is hereinafter abbreviated as EO) 10 mol adduct acrylates, methyl alcohol ethylene oxide 10 mol adduct methacrylate, lauryl alcohol EO 30 mol adduct acrylate, lauryl alcohol EO 30 mol adduct methacrylate), polyacrylates and polymethacrylates (polyacrylates and polymethacrylates of polyhydric alcohols: ethylene glycol diacrylate, ethylene glycol dimethacrylate, propylene glycol cold diacrylate, propylene glycol dimethacrylate, neopentyl glycol diacrylate, neopentyl glycol dimethacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate).
Carboxy group-containing vinyl ester: For example, carboxyalkyl acrylate having an alkyl chain of 3 to 20 carbon atoms, carboxyalkyl methacrylate having an alkyl chain of 3 to 20 carbon atoms.
Among these, styrene, butyl acrylate, β-carboxyethyl acrylate and the like are preferred.

Monomers that can be used in the production of the polyester resin include conventionally known divalent or trivalent or higher carboxylic acids and divalent or trivalent or higher alcohols. Specific examples of these monomers include the following.
Divalent carboxylic acids include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid, 1,11-undecanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,13-tridecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,16-hexadecanedicarboxylic acid, 1,18-octadecanedicarboxylic acid, phthalate acids, isophthalic acid, terephthalic acid, dibasic acids such as dodecenylsuccinic acid, their anhydrides or their lower alkyl esters, and aliphatic unsaturated dicarboxylic acids such as maleic acid, fumaric acid, itaconic acid and citraconic acid, etc. is mentioned. Lower alkyl esters and acid anhydrides of these dicarboxylic acids can also be used.
Examples of tricarboxylic or higher carboxylic acids include 1,2,4-benzenetricarboxylic acid, 1,2,5-benzenetricarboxylic acid, anhydrides thereof, and lower alkyl esters thereof.
These may be used individually by 1 type, and may use 2 or more types together.
Dihydric alcohols include alkylene glycols (1,2-ethanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octane Diol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,18-octadecane diols and 1,20-icosanediol.); alkylene ether glycols (polyethylene glycol and polypropylene glycol); cycloaliphatic diols (1,4-cyclohexanedimethanol); bisphenols (bisphenol A); Oxide (ethylene oxide and propylene oxide) adducts and alkylene oxides (ethylene oxide and propylene oxide) of bisphenols (bisphenol A) can be mentioned.
The alkyl portion of alkylene glycols and alkylene ether glycols may be linear or branched. In the present invention, branched alkylene glycol can also be preferably used.
Aliphatic diols with double bonds can also be used. Examples of aliphatic diols having double bonds include the following compounds.
2-butene-1,4-diol, 3-hexene-1,6-diol and 4-octene-1,8-diol.
Examples of trihydric or higher alcohols include glycerin, trimethylolethane, trimethylolpropane and pentaerythritol.
These may be used individually by 1 type, and may use 2 or more types together.
For the purpose of adjusting the acid value and hydroxyl value, monovalent acids such as acetic acid and benzoic acid and monovalent alcohols such as cyclohexanol and benzyl alcohol can be used as necessary.
The method for synthesizing the polyester resin is not particularly limited, but for example, transesterification or direct polycondensation can be used alone or in combination.

Next, the polyurethane resin will be described.
Polyurethane resins are reaction products of diols and compounds containing diisocyanate groups. By combining compounds containing various diols and diisocyanate groups, polyurethane resins having various functionalities can be obtained.
Examples of compounds containing a diisocyanate group include aromatic diisocyanates having 6 to 20 carbon atoms (excluding carbon in the NCO group, hereinafter the same), aliphatic diisocyanates having 2 to 18 carbon atoms, and 4 to 15 carbon atoms. and modified products of these diisocyanates (urethane group, carbodiimide group, allophanate group, urea group, biuret group, uretdione group, uretimine group, isocyanurate group or oxazolidone group-containing modified product. Hereinafter referred to as "modified diisocyanate Also referred to as "."), and mixtures of two or more thereof.
Aromatic diisocyanates include m- and/or p-xylylene diisocyanate (XDI) and α,α,α',α'-tetramethylxylylene diisocyanate.
Examples of aliphatic diisocyanates include ethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (HDI) and dodecamethylene diisocyanate.
Alicyclic diisocyanates include isophorone diisocyanate (IPDI), dicyclohexylmethane-4,4'-diisocyanate, cyclohexylene diisocyanate and methylcyclohexylene diisocyanate.
Among these, aromatic diisocyanates having 6 to 15 carbon atoms, aliphatic diisocyanates having 4 to 12 carbon atoms, and alicyclic diisocyanates having 4 to 15 carbon atoms are preferred, and XDI, IPDI and HDI are more preferred. In addition to the above diisocyanates, tri- or higher functional isocyanate compounds can also be used.
Examples of the diol that can be used for the polyurethane resin include the dihydric alcohols that can be used for the polyester described above.

As the binder resin, resins such as polyester resins, polyurethane resins and vinyl resins may be used singly or in combination of two or more. When two or more types are used together, the form of a composite resin in which the resins are chemically bonded to each other may be used.
From the viewpoint of low-temperature fixability, the glass transition temperature (Tg) of the binder resin is preferably 40.0° C. or higher and 120.0° C. or lower.

A known wax can be used as the wax.
Specifically, petroleum waxes such as paraffin wax, microcrystalline wax, petrolactam and derivatives thereof, montan wax and derivatives thereof, hydrocarbon waxes obtained by the Fischer-Tropsch process and derivatives thereof, polyolefin waxes typified by polyethylene and polypropylene, and Derivatives thereof, natural waxes such as carnauba wax and candelilla wax, derivatives thereof, and ester waxes are included.
Here, the derivatives include oxides, block copolymers with vinyl-based monomers, and graft-modified products. As the ester wax, a monofunctional ester wax containing one ester bond in one molecule, a bifunctional ester wax containing two ester bonds in one molecule, and multifunctional ester waxes such as tetrafunctional and hexafunctional ester waxes are used. be able to.
The content of the wax is preferably 1.0 parts by mass or more and 30.0 parts by mass or less, and is 3.0 parts by mass or more and 20.0 parts by mass or less with respect to 100.0 parts by mass of the binder resin. is more preferable.
By adjusting the content of the wax within the above range, the releasability of the toner particles can be further improved, and even when the temperature of the fixing member is low, the transfer paper is less likely to be wound. In addition, since the wax on the surface of the toner particles can be appropriately exposed, the wax is less likely to seep out to the surface of the toner particles even in a high-temperature environment, and the fluidity of the toner can be easily maintained at a high level. As a result, it is easy to suppress the occurrence of development streaks in a high-temperature environment.
The peak temperature of the maximum endothermic peak of the wax measured using a differential scanning calorimeter (DSC) is preferably 60°C or higher and 140°C or lower, more preferably 60°C or higher and 90°C or lower.
When the peak temperature of the maximum endothermic peak is within the above range, the magnetic toner is easily plasticized during fixation, and the low-temperature fixability is further improved. In addition, exudation of wax is less likely to occur even during long-term storage.

The wax forms domains inside the magnetic toner particles, and the number average diameter of the domains is preferably 50 nm or more and 500 nm or less, more preferably 100 nm or more and 400 nm or less.
The number average diameter of the domains is determined by randomly selecting 30 wax domains having a long axis of 20 nm or more in the cross section of the magnetic toner particles using a transmission electron microscope (TEM), and measuring the average of the long and short axes. was taken as the domain diameter, and the average value of 30 was taken as the number average diameter of the domain. It should be noted that the selection of domains need not be in the same toner particle.
When the number average diameter of the domains is within the above range, excessive agglomeration of the magnetic material can be suppressed, and the exudation of the wax to the toner particle surface in a high-temperature environment can be reduced. As a result, high fluidity of the toner can be easily maintained in a high-temperature environment, and the occurrence of development streaks can be further suppressed. In addition, even in a system such as a one-component contact development system that requires a high market share, it is easy to maintain the crystal structure of the wax. As a result, the exudation of the wax to the toner particle surface is reduced, and the occurrence of development streaks can be further suppressed.
The number average diameter of the domains can be adjusted by the amount of wax added, the diameter of the wax particles in the wax dispersion when the emulsion aggregation method is used as the toner production method, the retention time in the coalescence step, and the like. .

Ws is 1.5% or more and 18.0%, where Ws is the area percentage occupied by the wax in a region within 1.0 μm from the contour of the cross section of the magnetic toner particles observed with a transmission electron microscope. % or less, more preferably 2.0% or more and 15.0% or less.
When the Ws is within the above range, the amount of wax in the vicinity of the toner particle surface layer becomes appropriate, and localization of the magnetic material and uneven distribution of the wax on the toner particle surface can be prevented.
As a result, in a system such as a one-component contact development system that requires a high share of toner, it is possible to further suppress fog due to toner cracking and development streaks due to exudation of wax.
If the Ws is less than 1.5%, the wax tends to be unevenly distributed inside the toner and the magnetic material tends to be unevenly distributed on the surface. As a result, the toner tends to crack and fog easily.
On the other hand, when Ws exceeds 18.0%, the amount of wax increases near the surface layer of the toner. In a system such as a one-component contact development system that requires a high shear, the crystal structure of a part of the wax tends to collapse and the wax tends to melt when the toner is subjected to shear for a long period of time. As a result, the wax is more likely to seep out onto the toner surface, and development streaks are more likely to occur.
The Ws can be adjusted by the amount of wax added and the heat treatment time and heat treatment temperature in the toner manufacturing process. Further, when the emulsion aggregation method is used as the toner production method, it is preferable to control the aggregation speed of the wax and the timing of mixing with other materials.

In a cross section of the magnetic toner particles observed with a transmission electron microscope, the ratio of Wc to Ws is the ratio of Wc to Ws, where Wc is the percentage of the area occupied by the wax in the internal region inside 1.0 μm from the contour of the cross section. Wc/Ws) is preferably 2.0 or more and 10.0 or less, more preferably 3.0 or more and 8.0 or less.
When the Wc/Ws is within the above range, the wax is not localized on the surface layer of the toner particles. As a result, the amount of wax in the vicinity of the toner particle surface layer becomes appropriate, and localization of the magnetic material and uneven distribution of the wax on the toner particle surface can be prevented.
As a result, in a system such as a one-component contact development system that requires a high share of toner, it is possible to further suppress fogging due to toner cracking and development streaks caused by wax seepage, and obtain good images over a long period of time. be able to.
When Wc/Ws is less than 2.0, the amount of wax increases in the vicinity of the surface layer of the toner. In a system such as a one-component contact development system that requires a high shear, the wax crystal structure partially collapses and the wax melts when the toner is exposed to shear for a long period of time. As a result, the wax is more likely to seep out onto the toner surface, and development streaks are more likely to occur.
On the other hand, when Ws exceeds 10.0, the structure tends to be such that the magnetic material is unevenly distributed on the surface, cracking of the magnetic toner tends to occur, and fogging tends to occur.
The Wc/Ws can be adjusted by the amount of wax added and the heat treatment time and heat treatment temperature in the toner manufacturing process. Further, when the emulsion aggregation method is used as the toner production method, it is preferable to control the aggregation speed of the wax and the timing of mixing with other materials.

The magnetic material includes iron oxides such as magnetite, maghemite, and ferrite; metals such as iron, cobalt, and nickel; or these metals together with aluminum, copper, magnesium, tin, zinc, beryllium, calcium, manganese, selenium, and titanium. , alloys of metals such as tungsten, vanadium, and mixtures thereof.
The number average particle size of the primary particles of the magnetic material is preferably 0.50 μm or less, more preferably 0.05 μm or more and 0.30 μm or less.
The number average particle diameter of the primary particles of the magnetic material present in the toner particles can be measured using a transmission electron microscope.
Specifically, after sufficiently dispersing the toner particles to be observed in the epoxy resin, the mixture is cured in an atmosphere at a temperature of 40° C. for 2 days to obtain a cured product. The obtained cured product is treated with a microtome as a flaky sample, and an image is taken with a transmission electron microscope (TEM) at a magnification of 10,000 to 40,000 times. Measure the projected area. The equivalent diameter of a circle equal to the projected area is taken as the particle size of the primary particles of the magnetic material, and the average value of the 100 particles is taken as the number average particle size of the primary particles of the magnetic material.

It is preferable that the coercive force (Hc) is 1.6 to 12.0 kA/m as the magnetic properties of the magnetic material when 795.8 kA/m is applied. Also, the magnetization strength (σs) is preferably 50 to 200 Am ² /kg, more preferably 50 to 100 Am ² /kg. On the other hand, the residual magnetization (σr) is preferably 2 to 20 Am ² /kg.
The content of the magnetic substance in the magnetic toner is preferably 35% by mass or more and 50% by mass or less, more preferably 40% by mass or more and 50% by mass or less.
If the content of the magnetic substance is within the above range, the magnetic attractive force with the magnet roll inside the developing sleeve will be appropriate.
The content of the magnetic substance in the magnetic toner can be measured using a thermal analyzer TGA Q5000IR manufactured by PerkinElmer. The measurement method is to heat the magnetic toner from room temperature to 900°C at a temperature rising rate of 25°C/min in a nitrogen atmosphere, and take the weight loss from 100 to 750°C as the weight of the components of the magnetic toner excluding the magnetic material, and the residual weight. is the amount of magnetic material.

The magnetic material can be produced, for example, by the following method.
An aqueous solution containing ferrous hydroxide is prepared by adding an alkali such as sodium hydroxide in an amount equal to or greater than that of the iron component to the ferrous salt aqueous solution. While maintaining the pH of the prepared aqueous solution at 7 or higher, air is blown into the aqueous solution, and the ferrous hydroxide is oxidized while the aqueous solution is heated to 70°C or higher to generate seed crystals that will serve as the core of the magnetic iron oxide. .
Next, an aqueous solution containing about 1 equivalent of ferrous sulfate, based on the amount of alkali added previously, is added to the slurry containing the seed crystals. The pH of the mixed solution is maintained at 5 to 10, and the reaction of ferrous hydroxide is promoted while air is blown into the mixture to grow magnetic iron oxide with the seed crystal as the core. At this time, it is possible to control the shape and magnetic properties of the magnetic material by selecting arbitrary pH, reaction temperature, and stirring conditions. As the oxidation reaction progresses, the pH of the mixed solution shifts to the acidic side, but the pH of the solution should not be less than 5. A magnetic material can be obtained by filtering, washing, and drying the magnetic material thus obtained by a conventional method.
Moreover, the magnetic material may be subjected to a known surface treatment as necessary.

The magnetic toner particles may contain charge control agents. The magnetic toner is preferably negatively charged toner.
As charge control agents for negative charging, organometallic complex compounds and chelate compounds are effective, examples of which include monoazo metal complex compounds, acetylacetone metal complex compounds, and aromatic hydroxycarboxylic acid or aromatic dicarboxylic acid metal complex compounds. be done.
Specific examples of commercially available products include Spilon Black TRH, T-77, T-95 (Hodogaya Chemical Industry Co., Ltd.), BONTRON (registered trademark) S-34, S-44, S-54, E-84, E -88 and E-89 (Orient Chemical Industry Co., Ltd.).
The charge control agent can be used alone or in combination of two or more.
The content of the charge control agent is preferably 0.1 parts by mass or more and 10.0 parts by mass or less with respect to 100 parts by mass of the binder resin from the viewpoint of the charge amount. Although it is 0 mass part or less, it is more preferable.

The method for producing the magnetic toner is not particularly limited, and any of a dry method (e.g., kneading pulverization method, etc.) and a wet method (e.g., emulsion aggregation method, suspension polymerization method, dissolution suspension method, etc.) may be used. good. Among these, it is preferable to use the emulsion aggregation method.
When the emulsification aggregation method is used, the variation coefficient of the brightness dispersion value of the magnetic toner, the variation coefficient of the occupied area ratio of the magnetic substance, the number average diameter of the domains of the wax, and the above (Wc/Ws) can be adjusted within the above ranges. Easy.
A method for producing toner particles using the emulsion aggregation method will be described with specific examples.
The emulsion aggregation method is roughly divided into the following four steps.
(a) a step of preparing a fine particle dispersion, (b) an aggregation step of forming aggregated particles, (c) a coalescence step of forming toner particles by melting and coalescence, and (d) a washing and drying step.

(a) Step of Preparing Fine Particle Dispersion A fine particle dispersion is a dispersion of fine particles in an aqueous medium.
Examples of aqueous media include water such as distilled water and ion-exchanged water, and alcohols. These may be used individually by 1 type, and may use 2 or more types together.
Auxiliary agents for dispersing fine particles in an aqueous medium may be used, and examples of such auxiliary agents include surfactants.
Surfactants include anionic surfactants, cationic surfactants, amphoteric surfactants, and nonionic surfactants.
Specifically, anionic surfactants such as alkylbenzene sulfonates, α-olefin sulfonates, and phosphate esters; alkylamine salts, aminoalcohol fatty acid derivatives, polyamine fatty acid derivatives, amine salt types such as imidazoline, alkyl Quaternary ammonium salt type cationic surfactants such as trimethylammonium salts, dialkyldimethylammonium salts, alkyldimethylbenzylammonium salts, pyridinium salts, alkylisoquinolinium salts, and benzethonium chloride; fatty acid amide derivatives, polyhydric alcohol derivatives and amphoteric surfactants such as alanine, dodecyldi(aminoethyl)glycine, di(octylaminoethyl)glycine and N-alkyl-N,N-dimethylammonium betaine.
Surfactants may be used singly or in combination of two or more.

The method for preparing the fine particle dispersion can be appropriately selected according to the type of dispersoid.
For example, there is a method of dispersing the dispersoid using a general dispersing machine such as a rotary shearing homogenizer, a ball mill having media, a sand mill, or a dyno mill. In the case of a dispersoid that dissolves in an organic solvent, a phase inversion emulsification method may be used to disperse the dispersoid in an aqueous medium. In the phase inversion emulsification method, the material to be dispersed is dissolved in an organic solvent in which the material is soluble, the organic continuous phase (O phase) is neutralized, and then an aqueous medium (W phase) is added. In this method, the resin is converted from W/O to O/W (so-called phase inversion) to form a discontinuous phase, which is dispersed in an aqueous medium in the form of particles.
The solvent used in the phase inversion emulsification method is not particularly limited as long as it dissolves the resin, but it is preferable to use a hydrophobic or amphipathic organic solvent for the purpose of forming droplets.

It is also possible to prepare a fine particle dispersion by forming droplets in an aqueous medium and then polymerizing them, as in emulsion polymerization. Emulsion polymerization is a method of mixing a precursor of a material to be dispersed, an aqueous medium, and a polymerization initiator, followed by stirring or shearing to obtain a fine particle dispersion in which the material is dispersed in the aqueous medium. At this time, an organic solvent or a surfactant may be used as an emulsifying aid. Moreover, a general device may be used as a device for stirring or shearing, and a general dispersing machine such as a rotary shearing homogenizer may be used.
It is preferable to disperse the magnetic material having the target primary particle size in the aqueous medium. For dispersion, for example, a general dispersing machine such as a rotary shearing homogenizer, a ball mill having media, a sand mill, or a dyno mill may be used. Since the magnetic material has a higher specific gravity than water and a high sedimentation rate, it is preferable to immediately proceed to the aggregating step after dispersion.
The number average particle size of the dispersoids of the fine particle dispersion is preferably, for example, 0.01 μm or more and 1 μm or less, and 0.08 μm or more and 0.8 μm or less, from the viewpoints of aggregation rate control and coalescence simplicity. more preferably 0.1 μm or more and 0.6 μm or less.
From the viewpoint of controlling the aggregation speed, the dispersoid in the fine particle dispersion is preferably 5% by mass or more and 50% by mass or less, and preferably 10% by mass or more and 40% by mass or less. more preferred.

(b) Aggregation Step After preparing the fine particle dispersion, one kind of fine particle dispersion or two or more kinds of fine particle dispersions are mixed to prepare an aggregated particle dispersion in which aggregated particles are dispersed.
The mixing method is not particularly limited, and mixing can be performed using a general stirrer.
Aggregation is controlled by temperature, pH, aggregating agent, etc. of the aggregated particle dispersion, and any method may be used.
Regarding the temperature for forming aggregated particles, it is preferable that the glass transition temperature of the binder resin is −30° C. or more and the glass transition temperature or less.
Examples of aggregating agents include inorganic metal salts and divalent or higher metal complexes. Further, when a surfactant is used as an auxiliary agent in the fine particle dispersion, it is also effective to use a surfactant of opposite polarity. In particular, when a metal complex is used as the aggregating agent, the amount of surfactant used is reduced, and charging characteristics are improved. Examples of inorganic metal salts include metal salts such as sodium chloride, calcium chloride, calcium nitrate, barium chloride, magnesium chloride, magnesium sulfate, zinc chloride, aluminum chloride, aluminum sulfate, polyaluminum chloride, polyaluminum hydroxide, Examples include inorganic metal salt polymers such as calcium polysulfide.
A water-soluble chelating agent may be used as the chelating agent. Specific examples of chelating agents include oxycarboxylic acids such as tartaric acid, citric acid and gluconic acid, iminodiacid (IDA), nitrilotriacetic acid (NTA), and ethylenediaminetetraacetic acid (EDTA). The amount of the chelating agent to be added is, for example, preferably 0.01 parts by mass or more and 5.0 parts by mass or less, and 0.1 parts by mass or more and less than 3.0 parts by mass with respect to 100 parts by mass of the resin particles. It is more preferable to have

The timing of mixing the fine particle dispersion is not particularly limited, and the fine particle dispersion may be further added after or during formation of the aggregated particle dispersion to cause aggregation.
By controlling the addition timing of the fine particle dispersion, it is possible to control the structure in the toner.
Moreover, in the aggregating step, it is preferable to use a stirring device capable of controlling the stirring speed. The stirring device is not particularly limited, and any general-purpose emulsifier or disperser can be used.
For example, Ultra Turrax (manufactured by IKA), Polytron (manufactured by Kinematica), TK Auto Homo Mixer (manufactured by Tokushu Kika Kogyo Co., Ltd.), Ebara Milder (manufactured by Ebara Corporation), TK Homomic Line Flow (manufactured by Tokushu Kika Kogyo Co., Ltd.), Clearmix (manufactured by M Technic Co., Ltd.), and Filmix (manufactured by Tokushu Kika Kogyo Co., Ltd.) batch-type or continuous dual-use emulsifiers.
The stirring speed may be appropriately adjusted according to the production scale.
In particular, a magnetic material with a heavy specific gravity is easily affected by the stirring speed. By adjusting the stirring speed and stirring time, it is possible to control the particle size to the target. If the stirring speed is high, the aggregation is likely to be promoted, the aggregation of the magnetic material proceeds, and the final toner with low brightness tends to be formed.
On the other hand, when the stirring speed is slow, the magnetic material tends to settle, the aggregated particle dispersion liquid becomes non-uniform, and the amount of the magnetic material introduced tends to differ among the particles.
On the other hand, it is possible to control the aggregation state by adding a surfactant.

Aggregation is preferably stopped when the aggregated particles reach the target particle size.
Aggregation can be stopped by dilution, temperature control, pH control, addition of a chelating agent, addition of a surfactant, etc. Addition of a chelating agent is preferred from the standpoint of production. A more preferable method is to stop the aggregation by adding a chelating agent and adjusting the pH. When the addition of the chelating agent and the adjustment of the pH are used together, toner particles in which the magnetic material is slightly aggregated can be formed after the subsequent coalescence step.

(c) Coalescing Process After the aggregated particles are formed, they are heated to melt and coalesce to form toner particles.
The heating temperature is preferably higher than the glass transition temperature of the binder resin.
Further, after the aggregated particles are heated and coalesced, the fine particle dispersion is mixed, and the step of (b) forming the aggregated particles and (c) the step of melting and coalescing are performed to form toner particles having a core/shell structure. You may let

(d) Washing and Drying Steps Known washing methods, solid-liquid separation methods, and drying methods may be used, and are not particularly limited.
However, in the washing step, from the viewpoint of electrification, it is preferable to sufficiently perform displacement washing with ion-exchanged water. Moreover, in the solid-liquid separation step, it is preferable to apply suction filtration, pressure filtration, or the like from the viewpoint of productivity. In addition, from the viewpoint of productivity, the drying step may be performed by freeze drying, flash jet drying, fluidized drying, vibrating fluidized drying, or the like.

The magnetic toner particles may optionally be mixed with an external additive to improve the fluidity and/or chargeability of the toner to obtain a magnetic toner. A known apparatus such as a Henschel mixer may be used for mixing the external additive.
As the external additive, inorganic fine particles having a primary particle number average particle size of 4 nm or more and 80 nm or less can be exemplified, and inorganic fine particles having a number average particle size of 6 nm or more and 40 nm or less can be preferably exemplified.
The inorganic fine particles can further improve the chargeability and environmental stability of the toner when subjected to hydrophobic treatment. Treatment agents used for the hydrophobizing treatment include silicone varnishes, various modified silicone varnishes, silicone oils, various modified silicone oils, silane compounds, silane coupling agents, other organic silicon compounds, and organic titanium compounds. The treating agents may be used alone or in combination of two or more.
The number average particle diameter of the primary particles of the inorganic fine particles may be calculated using a toner image enlarged by a scanning electron microscope (SEM).

Examples of the inorganic fine particles include silica fine particles, titanium oxide fine particles, and alumina fine particles. As silica fine particles, for example, both so-called dry silica produced by vapor phase oxidation of a silicon halide, called so-called dry process or fumed silica, and so-called wet silica produced from water glass or the like can be used. is.
However, it is preferable to use dry silica, which has less silanol groups on the surface and inside the silica fine particles and less production residues such as Na ₂ O and SO ₃ ^2- .
In the dry silica, it is also possible to obtain composite fine particles of silica and other metal oxides by using other metal halide compounds such as aluminum chloride and titanium chloride together with silicon halide compounds in the manufacturing process. , which also includes them.
The content of the inorganic fine particles is preferably 0.1 parts by mass or more and 3.0 parts by mass or less with respect to 100 parts by mass of the toner particles. The content of inorganic fine particles may be quantified from a calibration curve prepared from standard samples using a fluorescent X-ray analyzer.

The magnetic toner may further contain other additives as long as they have no substantial adverse effect. Examples of such additives include lubricant powders such as fluororesin powder, zinc stearate powder, and polyvinylidene fluoride powder; abrasives such as cerium oxide powder, silicon carbide powder, and strontium titanate powder; and anti-caking agents. The additive can also be used after its surface has been subjected to a hydrophobic treatment.

The volume average particle diameter (Dv) of the magnetic toner is preferably 3.0 μm or more and 8.0 μm or less, more preferably 5.0 μm or more and 7.0 μm or less.
By setting the volume average particle diameter (Dv) of the toner within the above range, it is possible to sufficiently satisfy the reproducibility of dots while improving the handleability of the toner.
Also, the number average particle diameter (Dn) of the magnetic toner is preferably 3.0 μm or more and 7.0 μm or less.
Further, the ratio (Dv/Dn) of the volume average particle diameter (Dv) to the number average particle diameter (Dn) of the magnetic toner is preferably less than 1.25.
FIG. 3 shows an example of the relationship between the particle size of toner and the coefficient of variation of luminance dispersion value.

The average circularity of the magnetic toner is preferably from 0.960 to 1.000, more preferably from 0.970 to 0.990.
When the average circularity is within the above range, even in a system requiring a high share such as a one-component contact development system, the toner is less likely to be densified, and the toner tends to maintain fluidity. As a result, when a large number of images are output, it is possible to further suppress the decrease in image density and the occurrence of development streaks in the latter half.
The average circularity may be controlled by a method commonly used in the production of toner. For example, in the emulsion aggregation method, the time for the coalescence process and the amount of surfactant to be added may be controlled.

The image forming method of the present invention comprises
a charging step of externally applying a voltage to the charging member to charge the electrostatic latent image carrier;
a latent image forming step of forming an electrostatic latent image on the charged electrostatic latent image carrier;
a developing step of developing the electrostatic latent image with toner carried on a toner carrier to form a toner image on the electrostatic latent image carrier;
a transfer step of transferring the toner image on the electrostatic latent image bearing member to a transfer material with or without an intermediate transfer member;
An image forming method including a fixing step of fixing a toner image transferred to a transfer material by heating and pressurizing means,
The developing step is a one-component contact development system in which the electrostatic latent image bearing member and the toner carried on the toner bearing member are brought into direct contact with each other for development,
the toner is
A magnetic toner having magnetic toner particles containing a binder resin, wax and a magnetic substance,
Dn (μm) is the number average particle diameter of the magnetic toner,
CV1 (%) is the coefficient of variation of the luminance dispersion value in the particle size range of Dn−0.500 or more and Dn+0.500 or less of the magnetic toner,
When CV2 (%) is the variation coefficient of the luminance dispersion value in the particle size range of Dn-1.500 or more and Dn-0.500 or less of the magnetic toner, the CV1 and the CV2 are expressed by the following formula (1). satisfy relationships,
the magnetic toner has an average brightness of 30.0 to 60.0 in a particle size range of Dn−0.500 to Dn+0.500;
In a cross section of the magnetic toner using a transmission electron microscope,
A variation coefficient CV3 of an area ratio occupied by the magnetic material is 40.0% or more and 80.0% or less when a cross section of the magnetic toner is divided by a square grid having a side of 0.8 μm. . CV2/CV1≤1.00 (1)

The one-component contact development system is a development system in which a toner carrier and an electrostatic latent image carrier are arranged in contact (abutting arrangement), and these carriers transport toner by rotating. A large share is applied to the contact portion between the toner carrier and the electrostatic latent image carrier. Therefore, in order to obtain high-quality images, the toner preferably has high durability and high fluidity.
On the other hand, as a developing method, a one-component developing method allows a smaller cartridge containing a developer than a two-component developing method using a carrier.
Further, the contact development method can obtain high-quality images with less toner scattering. In other words, the one-component contact developing system, which has both of the above, can achieve both the miniaturization of the developing device and the improvement of image quality.

The one-component contact development system will be described in detail below with reference to the drawings.
FIG. 1 is a schematic cross-sectional view showing an example of a developing device. FIG. 2 is a schematic cross-sectional view showing an example of a one-component contact development type image forming apparatus.
In FIG. 1 or 2, the electrostatic latent image carrier 45 on which the electrostatic latent image is formed is rotated in the direction of arrow R1. By rotating the toner carrier 47 in the direction of the arrow R2, the toner 57 is conveyed to the development area where the toner carrier 47 and the electrostatic latent image carrier 45 face each other. A toner supply member 48 is in contact with the toner carrier 47 and supplies toner 57 to the surface of the toner carrier 47 by rotating in the direction of arrow R3. Further, the toner 57 is stirred by the stirring member 58 .
A charging member (charging roller) 46 , a transfer member (transfer roller) 50 , a cleaner container 43 , a cleaning blade 44 , a fixing device 51 , a pickup roller 52 and the like are provided around the electrostatic latent image carrier 45 . The electrostatic latent image carrier 45 is charged by a charging roller 46 . Then, the electrostatic latent image carrier 45 is exposed by irradiating the electrostatic latent image carrier 45 with laser light from the laser generator 54 to form an electrostatic latent image corresponding to the desired image. The electrostatic latent image on the electrostatic latent image carrier 45 is developed with toner 57 in the developing device 49 to obtain a toner image. The toner image is transferred onto a transfer material (paper) 53 by a transfer member (transfer roller) 50 in contact with the electrostatic latent image carrier 45 via the transfer material. Transfer of the toner image to the transfer material may occur via an intermediate transfer member. A transfer material (paper) 53 carrying a toner image is conveyed to a fixing device 51 and the toner image is fixed on the transfer material (paper) 53 . A portion of the toner 57 left on the electrostatic latent image carrier 45 is scraped off by the cleaning blade 44 and stored in the cleaner container 43 .
Further, it is preferable that the toner regulating member (reference numeral 55 in FIG. 1) contacts the toner carrier through the toner to regulate the thickness of the toner layer on the toner carrier. By doing so, it is possible to obtain a high image quality without defective regulation. A regulating blade is generally used as the toner regulating member that contacts the toner carrier.
The upper side of the regulating blade is fixed to the developing device, and the lower side of the regulating blade is bent in the forward or reverse direction of the toner carrier against the elastic force of the blade. should be brought into contact with an appropriate elastic pressing force.
For example, as shown in FIG. 1, one free end of the toner regulating member 55 is sandwiched between two fixing members (for example, metal elastic bodies, reference numeral 56 in FIG. 1) to fix the toner regulating member 55 to the developing device. It should be fixed with fasteners.

Methods for measuring each physical property value according to the present invention are described below.
<Method for Measuring Volume Average Particle Diameter (Dv) and Number Average Particle Diameter (Dn) of Magnetic Toner>
The volume average particle diameter (Dv) and number average particle diameter (Dn) of the magnetic toner are calculated as follows.
As a measuring device, a precision particle size distribution measuring device "Coulter Counter Multisizer 3" (registered trademark, manufactured by Beckman Coulter, Inc.) using a pore electrical resistance method equipped with a 100 μm aperture tube is used. The attached dedicated software "Beckman Coulter Multisizer 3 Version 3.51" (manufactured by Beckman Coulter, Inc.) is used for setting the measurement conditions and analyzing the measurement data. The measurement is performed with 25,000 effective measurement channels.
As the electrolytic aqueous solution used for measurement, a solution obtained by dissolving special grade sodium chloride in ion-exchanged water to a concentration of about 1% by mass, for example, "ISOTON II" (manufactured by Beckman Coulter, Inc.) can be used.
Before performing measurement and analysis, set the dedicated software as follows.
On the "Change standard measurement method (SOM)" screen of the dedicated software, set the total number of counts in control mode to 50,000 particles, set the number of measurements to 1, and set the Kd value to "standard particle 10.0 μm" (Beckman Coulter, Inc. (manufactured) to set the value obtained using By pressing the "threshold/noise level measurement button", the threshold and noise level are automatically set. Also, set the current to 1600 μA, the gain to 2, the electrolytic aqueous solution to ISOTON II, and put a check in the “Flush aperture tube after measurement” box.
On the "pulse-to-particle size conversion setting" screen of the dedicated software, set the bin interval to logarithmic particle size, the particle size bin to 256 particle size bins, and the particle size range from 2 μm to 60 μm.
A specific measuring method is as follows.
(1) About 200 mL of the electrolytic aqueous solution is placed in a 250 mL glass round-bottomed beaker exclusively for Multisizer 3, set on a sample stand, and stirred counterclockwise at 24 rpm with a stirrer rod. Then, remove the dirt and air bubbles inside the aperture tube using the dedicated software's "Flush Aperture Tube" function.
(2) About 30 mL of the electrolytic aqueous solution is placed in a 100 mL flat-bottom glass beaker. As a dispersant, "Contaminon N" (a 10% by mass aqueous solution of a neutral detergent for cleaning precision measuring instruments at pH 7 consisting of a nonionic surfactant, an anionic surfactant, and an organic builder, manufactured by Wako Pure Chemical Industries, Ltd.) was used as a dispersant. ) is diluted with ion-exchanged water to about 3 times the mass, and about 0.3 mL of the diluted solution is added.
(3) Prepare an ultrasonic disperser "Ultrasonic Dispersion System Tetora 150" (manufactured by Nikkaki Bios Co., Ltd.) having an electrical output of 120 W and incorporating two oscillators with an oscillation frequency of 50 kHz with a phase shift of 180°. About 3.3 L of ion-exchanged water is placed in the water tank of the ultrasonic disperser, and about 2 mL of Contaminon N is added to this water tank.
(4) The beaker of (2) is set in the beaker fixing hole of the ultrasonic disperser, and the ultrasonic disperser is operated. Then, the height position of the beaker is adjusted so that the resonance state of the liquid surface of the electrolytic aqueous solution in the beaker is maximized.
(5) While the electrolytic aqueous solution in the beaker in (4) above is being irradiated with ultrasonic waves, about 10 mg of toner is added little by little to the electrolytic aqueous solution and dispersed. Then, the ultrasonic dispersion treatment is continued for another 60 seconds. The ultrasonic dispersion is appropriately adjusted so that the temperature of the water in the water tank is 10°C or higher and 40°C or lower.
(6) The electrolytic aqueous solution of (5) above, in which the toner is dispersed, is dropped into the round-bottomed beaker of (1) above set in the sample stand, and adjusted so that the measured concentration is about 5%. . The measurement is continued until the number of measured particles reaches 50,000.
(7) Analyze the measurement data with the dedicated software attached to the apparatus, and calculate the volume average particle size (Dv) and the number average particle size (Dn). In addition, when the graph / volume% is set with the dedicated software, the "50% D diameter" on the "analysis / volume statistical value (arithmetic mean)" screen is the volume average particle diameter (Dv), and the graph / The "arithmetic diameter" on the "analysis/number statistical value (arithmetic mean)" screen when the number % was set was taken as the number average particle diameter (Dn).

<Method for Measuring Average Brightness, Brightness Dispersion Value, Variation Coefficient, and Average Circularity of Magnetic Toner>
The average brightness, brightness dispersion value and coefficient of variation thereof, and average circularity of the magnetic toner are measured using a flow type particle image analyzer "FPIA-3000" (manufactured by Sysmex Corporation) under measurement and analysis conditions during calibration work.
A specific measuring method is as follows.
First, about 20 mL of ion-exchanged water, from which solid impurities have been removed in advance, is placed in a glass container. As a dispersant, "Contaminon N" (a 10% by mass aqueous solution of a neutral detergent for cleaning precision measuring instruments at pH 7 consisting of a nonionic surfactant, an anionic surfactant, and an organic builder, manufactured by Wako Pure Chemical Industries, Ltd.) was used as a dispersant. ) is diluted with ion-exchanged water to about 3 times the mass, and about 0.2 mL of the diluted solution is added. Further, about 0.02 g of a measurement sample is added, and dispersion treatment is performed for 2 minutes using an ultrasonic disperser to obtain a dispersion liquid for measurement. At that time, the temperature of the dispersion liquid is appropriately cooled to 10° C. or higher and 40° C. or lower. As the ultrasonic disperser, a desktop ultrasonic cleaner disperser "VS-150" (manufactured by Vervoclea) with an oscillation frequency of 50 kHz and an electrical output of 150 W was used. and about 2 mL of the contaminon N is added to the water bath.
For the measurement, the flow-type particle image analyzer equipped with "LUCPLFLN" (magnification 20 times, numerical aperture 0.40) as the objective lens was used, and the sheath liquid was the particle sheath "PSE-900A" (manufactured by Sysmex Corporation). to use. The dispersion liquid prepared according to the above procedure is introduced into the flow type particle image analyzer, and 2000 magnetic toner particles are counted in the HPF measurement mode and the total count mode. From the results, the average brightness, brightness dispersion value, and average circularity of the toner are calculated.

For the average brightness of the magnetic toner, the circle equivalent diameter of the present flow type particle image analyzer is Dn-0.500 (μm) or more and Dn+0.500 (
μm), and the average luminance is calculated.
CV1 is the measurement result of the luminance dispersion value, and the circle equivalent diameter of the flow type particle image analyzer is Dn-0.500 (μm) or more and Dn+0 with respect to the result of the number average particle diameter (Dn) of the magnetic toner. This is a value obtained by calculating the coefficient of variation of the luminance variance value, limited to the range of 0.500 (μm) or less.
CV2 is the measurement result of the luminance dispersion value, and the circle equivalent diameter of the flow type particle image analyzer is Dn-1.500 (μm) or more with respect to the result of the number average particle diameter (Dn) of the magnetic toner. This is a value obtained by calculating the coefficient of variation of the brightness variance value, limited to the range of −0.500 (μm) or less.
In the measurement, automatic focus adjustment is performed using standard latex particles (“RESEARCH AND TEST PARTICLES Latex Microsphere Suspensions 5100A” manufactured by Duke Scientific, diluted with deionized water) before starting the measurement. After that, it is preferable to perform focus adjustment every two hours from the start of measurement.
In this case, we use a flow-type particle image analyzer that has been calibrated by Sysmex and has received a calibration certificate issued by Sysmex.
Except for limiting the analyzed particle diameter to a circle equivalent diameter of 1.977 μm or more and less than 39.54 μm, the measurement is performed under the measurement and analysis conditions when the calibration certificate was received.

<Measuring method of melting point>
The melting point of the resin or wax is measured using a differential scanning calorimeter (DSC) Q2000 (manufactured by TA Instruments) under the following conditions.
Heating rate: 10°C/min
Measurement start temperature: 20°C
Measurement end temperature: 180°C
The melting points of indium and zinc are used to correct the temperature of the device detector, and the heat of fusion of indium is used to correct the amount of heat.
Specifically, about 5 mg of a sample is accurately weighed, placed in an aluminum pan, and measured once. An empty aluminum pan is used as a reference. Let the peak temperature of the maximum endothermic peak at that time be melting|fusing point.

<Method for measuring glass transition temperature (Tg)>
The glass transition temperature of a resin or the like is measured in the vertical axis direction from a straight line obtained by extending the baseline before and after the change in specific heat in the reversing heat flow curve during temperature rise obtained by differential scanning calorimetry of the melting point. is the temperature (° C.) at the intersection of a straight line equidistant to , and the curve of the step change portion of the glass transition in the reversing heat flow curve.

<Method for measuring number average molecular weight (Mn) and weight average molecular weight (Mw) of resin>
The number average molecular weight (Mn) and weight average molecular weight (Mw) of resins and other materials are measured using gel permeation chromatography (GPC) as follows.
(1) Preparation of measurement sample A sample and tetrahydrofuran (THF) are mixed at a concentration of 5.0 mg/mL, left at room temperature for 5 to 6 hours, and then shaken sufficiently to combine THF and the sample. Mix well until there are no lumps. Furthermore, it is allowed to stand at room temperature for 12 hours or longer. At this time, the tetrahydrofuran (THF)-soluble portion of the sample is obtained by setting the time from the start of mixing of the sample and THF to the end of standing to be 72 hours or longer.
Then, it is filtered through a solvent-resistant membrane filter (pore size: 0.45 to 0.50 μm, Myshoridisc H-25-2 [manufactured by Tosoh Corporation]) to obtain a sample solution.
(2) Measurement of sample Using the obtained sample solution, measure under the following conditions.
Apparatus: High-speed GPC apparatus LC-GPC 150C (manufactured by Waters)
Column: 7 series of Shodex GPC KF-801, 802, 803, 804, 805, 806, 807 (manufactured by Showa Denko) Mobile phase: THF
Flow rate: 1.0 mL/min
Column temperature: 40°C
Sample injection volume: 100 μL
Detector: RI (Refractive Index) Detector In measuring the molecular weight of a sample, the molecular weight distribution of the sample is calculated from the relationship between the logarithmic value of a calibration curve prepared from several types of monodisperse polystyrene standard samples and the number of counts.
As a standard polystyrene sample for preparing a calibration curve, Pressure Chemical Co. or Toyo Soda Kogyo Co., Ltd., molecular weights of 6.0×10 ² , 2.1×10 ³ , 4.0×10 ³ , 1.75×10 ⁴ , 5.1×10 ⁴ , 1.1× 10 ⁵ , 3.9×10 ⁵ , 8.6×10 ⁵ , 2.0×10 ⁶ and 4.48×10 ⁶ are used.

<Method for measuring the particle diameter of the dispersion in the fine particle dispersion>
The particle size of each fine particle dispersion liquid was measured using a laser diffraction/scattering particle size distribution analyzer. Specifically, it is measured according to JIS Z 8825-1 (2001).
As a measuring device, a laser diffraction/scattering particle size distribution measuring device “LA-920” (manufactured by Horiba Ltd.) is used.
Dedicated software "HORIBA LA-920 for Windows (registered trademark) WET (LA-920) Ver.2.02" attached to LA-920 is used for setting measurement conditions and analyzing measurement data. As the measurement solvent, ion-exchanged water from which impure solids and the like have been previously removed is used. The measurement procedure is as follows.
(1) Attach the batch type cell holder to LA-920.
(2) Put a predetermined amount of ion-exchanged water in a batch-type cell, and set the batch-type cell in a batch-type cell holder.
(3) Stir the inside of the batch-type cell using a dedicated stirrer tip.
(4) Press the "refractive index" button on the "display condition setting" screen to set the relative refractive index to a value corresponding to the fine particles.
(5) On the "Display condition setting" screen, the particle size standard is set to the volume standard.
(6) After performing warm-up operation for 1 hour or longer, perform optical axis adjustment, fine adjustment of the optical axis, and blank measurement.
(7) Put 3 mL of the fine particle dispersion into a 100 mL flat-bottom glass beaker. Further, 57 mL of ion-exchanged water is added to dilute the fine resin particle dispersion. As a dispersant, "Contaminon N" (a 10% by mass aqueous solution of a neutral detergent for washing precision measuring instruments at pH 7 consisting of a nonionic surfactant, an anionic surfactant, and an organic builder, Wako Pure Chemical Industries, Ltd. ) is diluted with ion-exchanged water to 3 times the mass, and 0.3 mL of the diluted solution is added.
(8) Prepare an ultrasonic disperser "Ultrasonic Dispersion System Tetora 150" (manufactured by Nikkaki Bios Co., Ltd.) having an electrical output of 120 W and incorporating two oscillators with an oscillation frequency of 50 kHz with a phase shift of 180 degrees. 3.3 L of deionized water is placed in the water tank of the ultrasonic disperser, and 2 mL of Contaminon N is added to this water tank. (9) Set the beaker of (7) in the beaker fixing hole of the ultrasonic disperser, and operate the ultrasonic disperser. Then, the height position of the beaker is adjusted so that the resonance state of the liquid surface of the aqueous solution in the beaker is maximized.
(10) Continue the ultrasonic dispersion treatment for 60 seconds. Also, in ultrasonic dispersion, the temperature of the water in the water tank is appropriately adjusted to 10° C. or higher and 40° C. or lower.
(11) Immediately add the fine particle dispersion prepared in (10) little by little to the batch cell while taking care not to introduce air bubbles so that the transmittance of the tungsten lamp is 90% to 95%. adjust. Then, the particle size distribution is measured. Based on the obtained volume-based particle size distribution data, the particle size of the dispersion in the fine particle dispersion is calculated.

<Method for Calculating Occupied Area Ratio of Magnetic Substance in Magnetic Toner and Its Variation Coefficient (CV3)>
The occupied area ratio of the magnetic substance in the magnetic toner and its coefficient of variation (CV3) are calculated as follows.
First, a cross-sectional image of the magnetic toner is acquired using a transmission electron microscope (TEM). A frequency histogram of the occupied area ratio of the magnetic material in each section grid is obtained based on the division method for the obtained cross-sectional image.
Furthermore, the variation coefficient of the occupied area ratio of each division grid obtained is calculated and set as the occupied area ratio variation coefficient (CV3).
Specifically, first, the magnetic toner is compression-formed into a tablet. A tablet forming machine with a diameter of 8 mm is filled with 100 mg of magnetic toner, and a force of 35 kN is applied to it and allowed to stand still for 1 minute to obtain tablets.
The resulting tablet is cut with an ultrasonic ultramicrotome (Leica, UC7) to obtain a slice sample with a film thickness of 250 nm.
An STEM image is taken of the obtained flake sample using a transmission electron microscope (JEOL, JEM2800).
Assume that the probe size used for photographing the STEM image is 1.0 nm, and the image size is 1024×1024 pixels. At this time, by adjusting the Contrast of the Detector Control panel of the bright field image to 1425, Brightness to 3750, Contrast of the Image Control panel to 0.0, Brightness to 0.5, and Gammma to 1.00, only the magnetic material portion can be shot in the dark. With this setting, a STEM image suitable for image processing can be obtained.
The obtained STEM image is digitized using an image processing apparatus (Nireco Corporation, LUZEX AP).
Specifically, a frequency histogram of the occupied area ratio of the magnetic material on a square grid with one side of 0.8 μm is obtained by the division method. At this time, the class interval of the histogram is set to 5%.
Further, a variation coefficient is obtained from the obtained occupied area ratio of each division grid, and is set as the occupied area ratio variation coefficient CV3. Also, the average value of the occupied area ratio is obtained by averaging the occupied area ratio of each division grid.

<Method for calculating number average diameter of domains of wax>
The magnetic toner was embedded in a visible light curable embedding resin (D-800, manufactured by Nissin EM), cut to a thickness of 60 nm using an ultrasonic ultramicrotome (EM5, manufactured by Leica), and subjected to a vacuum dyeing apparatus (Filgen). company) for Ru staining.
After that, using a transmission electron microscope (H7500, manufactured by Hitachi High-Technology Co., Ltd.), the cross section of the obtained magnetic toner particles is observed at an accelerating voltage of 120 kV.
Ten magnetic toner particles within ±2.0 μm from the number-average particle size of the magnetic toner particles are selected and photographed to obtain a cross-sectional image.
It should be noted that, compared to amorphous resins and magnetic materials, wax does not progress in staining with Ru and appears white in the cross-sectional image.
The number average diameter of the wax domains is obtained by randomly selecting 30 wax domains having a long axis of 20 nm or more in the cross-sectional image, and taking the average value of the long and short axes as the domain diameter, and calculating the average value of the 30 domains. It is the number-average diameter of domains. Note that the selection of domains need not be in the same magnetic toner particle.

<How to calculate Ws and Wc>
The wax distribution state in the magnetic toner is evaluated by calculating Ws and Wc from the area of the wax domain in the cross-sectional image, and averaging 10 arbitrarily selected magnetic toners. Using image processing software (Photoshop 5.0, manufactured by Adobe), "
Perform the “2-gradation” process in “color tone correction”.
The threshold is set to an offset gradation on the low gradation side of the gradation peak indicating the binder resin in the gradation distribution of 255 gradations of the image. This two-gradation processing provides an image in which the wax domain and the binder resin region are clearly distinguished.
Furthermore, in the cross-sectional image, a region within 1.0 μm (including the boundary of 1.0 μm) from the contour of the cross section is left masked, and the wax having a long axis of 20 nm or more in the obtained region within 1.0 μm The percentage of area occupied by the domain is calculated as the percentage of area occupied by wax, and this is defined as Ws.
On the other hand, the occupied area percentage of wax domains having a long axis of 20 nm or more in the inner region 1.0 μm from the contour of the cross section is calculated as the wax occupied area percentage, and this is defined as Wc.

EXAMPLES The present invention will be described in more detail below with reference to Examples and Comparative Examples, but the present invention is not limited to these. All parts and percentages in Examples and Comparative Examples are based on mass unless otherwise specified.

<Production example of polyester 1>
・Terephthalic acid 30.0 parts ・Isophthalic acid 12.0 parts ・Dodecenyl succinic acid 40.0 parts ・Trimellitic acid 4.2 parts ・Bisphenol A ethylene oxide (2 mol) adduct 80.0 parts ・Bisphenol A propylene oxide ( 2 mol) Adduct: 74.0 parts Dibutyl tin oxide: 0.1 part The above materials were placed in a heat-dried two-necked flask, and the temperature was raised while maintaining an inert atmosphere by introducing nitrogen gas into the vessel and stirring. After that, polycondensation reaction was carried out at 150-230° C. for about 12 hours, and then the pressure was gradually reduced at 210-250° C. to obtain polyester 1.
Polyester 1 had a number average molecular weight (Mn) of 18,200, a weight average molecular weight (Mw) of 74,100, and a glass transition temperature (Tg) of 58.6°C.

<Production Example of Resin Particle Dispersion 1>
In a beaker with a stirrer, 100.0 parts of ethyl acetate, 30.0 parts of polyester 1, 0.1 mol / L of sodium hydroxide 0.3 parts, and an anionic surfactant (Daiichi Kogyo Seiyaku ( 0.2 part of Neogen RK manufactured by Co., Ltd. was added, heated to 60.0° C., and stirred until completely dissolved to prepare a resin solution 1.
While further stirring the resin solution 1, 120.0 parts of ion-exchanged water was gradually added to effect phase inversion emulsification, and the solvent was removed to obtain a resin particle dispersion 1 (solid concentration: 20.0% by mass). Obtained.
The volume average particle diameter of the resin particles in the resin particle dispersion liquid 1 was 0.18 μm.

<Production Example of Resin Particle Dispersion Liquid 2>
・Styrene 78.0 parts ・n-butyl acrylate 20.0 parts ・β-carboxyethyl acrylate 2.0 parts ・1,6 hexanediol diacrylate 0.4 parts ・Dodecanethiol (manufactured by Wako Pure Chemical Industries) 0.7 parts The above materials were added to the flask, mixed and dissolved to obtain a solution.
The resulting solution was dispersed and emulsified in an aqueous medium prepared by dissolving 1.0 part of an anionic surfactant (Neogen RK, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) in 250 parts of ion-exchanged water.
While slowly stirring and mixing for 10 minutes, 50 parts of ion-exchanged water containing 2 parts of ammonium persulfate dissolved therein was added.
Then, after the inside of the system was sufficiently replaced with nitrogen, the inside of the system was heated with stirring in an oil bath until the temperature reached 70° C., and the emulsion polymerization was continued for 5 hours. 0% by mass) was obtained.
The resin particles in the resin particle dispersion 2 had a volume average particle size of 0.18 μm, a glass transition temperature (Tg) of 56.5° C., and a weight average molecular weight (Mw) of 30,000.

<Production Example of Wax Dispersion 1>
・ Paraffin wax 50.0 parts (manufactured by Nippon Seiro Co., Ltd., HNP-9)
- Anionic surfactant 0.3 parts (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., Neogen RK)
- Ion-exchanged water 150.0 parts The above was mixed, heated to 95°C, and dispersed using a homogenizer (manufactured by IKA, Ultra Turrax T50). Thereafter, dispersion treatment was performed using a Manton-Gaulin high-pressure homogenizer (manufactured by Gaolin) to prepare a wax dispersion 1 (solid concentration: 25.0% by mass) in which wax particles were dispersed. The volume average particle size of the obtained wax particles was 0.20 μm.

<Production Examples of Wax Dispersions 2 and 3>
Wax dispersions 2 and 3 were obtained by appropriately adjusting the dispersion treatment time and the amount of surfactant added in the production example of wax dispersion 1. Table 1 shows the volume average particle size of the wax particles in each wax dispersion.

<Manufacturing Example of Magnetic Body 1>
50 liters of an aqueous solution of ferrous sulfate containing 2.0 mol/L of Fe ²⁺ was mixed with 55 liters of an aqueous solution of 4.0 mol/L sodium hydroxide, and a ferrous salt aqueous solution containing ferrous hydroxide colloid was obtained. Obtained. This aqueous solution was kept at 85° C. and an oxidation reaction was carried out while blowing air at 20 L/min to obtain a slurry containing core particles.
After filtering and washing the resulting slurry with a filter press, the core particles were dispersed again in water. To the obtained reslurry liquid, sodium silicate having a content of 0.20% by mass in terms of silicon per 100 parts of the core particles is added, the pH of the slurry liquid is adjusted to 6.0, and the silicon-rich surface is formed by stirring. magnetic iron oxide particles having
The resulting slurry liquid was filtered with a filter press, washed, and reslurried with deionized water. To this reslurry liquid (solid content: 50 parts/L), 500 parts (10 mass % with respect to magnetic iron oxide) of ion exchange resin SK110 (manufactured by Mitsubishi Chemical) was added and stirred for 2 hours to perform ion exchange. Thereafter, the ion exchange resin was removed by filtration through a mesh, filtered and washed with a filter press, dried and pulverized to obtain a magnetic substance 1 having primary particles with a number average particle diameter of 0.21 μm.

<Manufacturing example of magnetic bodies 2 and 3>
Magnetic bodies 2 and 3 were obtained in the same manner as in the production example of magnetic body 1, except that the amount of blown air and the oxidation reaction time were adjusted. Table 2 shows the number average particle diameter of the primary particles of each magnetic material.

<Production Example of Magnetic Dispersion 1>
・Magnetic substance 1 25.0 parts ・Ion-exchanged water 75.0 parts The above materials are mixed and dispersed at 8000 rpm for 10 minutes using a homogenizer (manufactured by IKA, Ultra Turrax T50). Obtained. The volume average particle size of the magnetic substance in the magnetic substance dispersion liquid 1 was 0.23 μm.

<Manufacturing Examples of Magnetic Dispersions 2 and 3>
Magnetic substance dispersion liquids 2 and 3 were produced in the same manner as in the manufacturing example of magnetic substance dispersion liquid 1, except that magnetic substance 1 was changed to magnetic substance 2 or 3. The volume average particle diameter of the magnetic substance in the obtained magnetic substance dispersion liquid 2 was 0.18 μm, and the volume average particle diameter of the magnetic substance in the magnetic substance dispersion liquid 3 was 0.35 μm.

<Production Example of Magnetic Toner Particles 1>
・Resin particle dispersion 1 (solid content: 20.0% by mass) 150.0 parts ・Wax dispersion 1 (solid content: 25.0% by mass) 15.0 parts ・Magnetic substance dispersion 1 (solid content: 25.0% by mass) %) 105.0 parts The above materials were put into a beaker, and after adjusting the total number of parts of water to 250 parts, the temperature was adjusted to 30.0°C. After that, using a homogenizer (manufactured by IKA, Ultra Turrax T50), they were mixed by stirring at 5000 rpm for 1 minute.
Further, 10.0 parts of a 2.0% by mass aqueous solution of magnesium sulfate was gradually added as a flocculating agent.
The raw material dispersion was transferred to a polymerization vessel equipped with a stirrer and a thermometer, heated to 50.0° C. with a mantle heater, and stirred to promote the growth of aggregated particles.
After 60 minutes had passed, 200.0 parts of a 5.0 mass % aqueous solution of ethylenediaminetetraacetic acid (EDTA) was added to prepare an aggregated particle dispersion liquid 1.
Subsequently, after adjusting the aggregated particle dispersion liquid 1 to pH 8.0 using a 0.1 mol/L sodium hydroxide aqueous solution, the aggregated particle dispersion liquid 1 was heated to 80.0° C. and allowed to stand for 180 minutes. Coalescence of agglomerated particles was carried out.
After 180 minutes, a toner particle dispersion liquid 1 in which toner particles are dispersed is obtained. After cooling at a cooling rate of 1.0° C./min, the toner particle dispersion liquid 1 was filtered and washed with ion-exchanged water. Toner particles were removed.
Next, the cake-like toner particles are put into ion-exchanged water of 20 times the mass of the toner particles, stirred with a three-one motor, and filtered again when the toner particles are sufficiently loosened.
Solid-liquid separation was performed by washing with water. The resulting caked toner particles were pulverized with a sample mill and dried in an oven at 40° C. for 24 hours. Further, the obtained powder was pulverized with a sample mill and then additionally vacuum-dried in an oven at 40° C. for 5 hours to obtain magnetic toner particles 1 .

<Production Example of Magnetic Toner 1>
To 100 parts of magnetic toner particles 1, 0.3 part of sol-gel silica fine particles having a primary particle number average particle size of 115 nm was added and mixed using an FM mixer (manufactured by Nippon Coke Industry Co., Ltd.).
Thereafter, silica fine particles having a number average primary particle size of 12 nm were further treated with hexamethyldisilazane and then treated with silicone oil, and the BET specific surface area after treatment was 0.9. parts were added and similarly mixed using an FM mixer (manufactured by Nippon Coke Kogyo Co., Ltd.) to obtain Magnetic Toner 1.
Table 4 shows the following results for the magnetic toner 1 obtained.
Volume average particle size (Dv), number average particle size (Dn), average brightness in the particle size range of Dn-0.500 or more and Dn+0.500 or less [in the table, simply referred to as average brightness], CV1, CV2/ CV1, the average value of the occupied area ratio of the magnetic substance [indicated as A in the table], the average circularity, the number average diameter of the wax domains [indicated as B in the table].

<Example 1>
(Image forming device)
A one-component contact development type LaserJet Pro M12 (manufactured by Hewlett-Packard Co.) was modified to 200 mm/sec, which is faster than the original process speed, and used.
100 g of the magnetic toner 1 was filled in the apparatus modified as described above, and under a low temperature and low humidity environment (15.0° C./10.0% RH) and a high temperature and high humidity environment (32.5° C./80% RH). A repeated use test was performed on each.
As an output image for the test, a horizontal line image with a print rate of 1% was printed on 4000 sheets by intermittent feeding of two sheets.
As the evaluation paper used in the test, business 4200 (manufactured by Xerox) having a basis weight of 75 g/m ² was used.
In addition, Table 6 shows the evaluation results. In addition, the evaluation method and evaluation criteria in each evaluation are as follows.

<Evaluation of image density under low temperature and low humidity environment>
The image density was measured by forming a solid black image portion and measuring the density of this solid black image with a Macbeth reflection densitometer (manufactured by Macbeth).
The criteria for judging the reflection density of a solid black image before long-term use are as follows.
[Evaluation criteria]
A: 1.45 or more B: 1.40 or more and less than 1.45 C: 1.35 or more and less than 1.40 D: less than 1.35

Criteria for judging the change in image density in the second half of the endurance use are as follows.
The smaller the difference between the reflection density of the solid black image before long-term use and the reflection density of the solid black image output after printing 4000 sheets in the repeated use test, the better.
[Evaluation criteria]
A: Density difference is less than 0.10 B: Density difference is 0.10 or more and less than 0.15 C: Density difference is 0.15 or more and less than 0.20 D: Density difference is 0.20 or more

<Evaluation of Fog under Low Temperature and Low Humidity Environment>
Fog was measured using a REFLECTMETER MODEL TC-6DS manufactured by Tokyo Denshoku. A green filter was used as the filter.
For the evaluation, after printing 4000 sheets in the repeated use test, first, a solid black image was output.
An area of the electrostatic latent image bearing member corresponding to a white background portion (non-image portion) immediately after transfer of the solid black image was taped off with Mylar tape, and the Mylar tape was pasted on the paper.
The fog value was obtained by subtracting the reflectance of the peeled Mylar tape on virgin paper from the reflectance of the Mylar tape alone on virgin paper.
[Evaluation criteria]
A: Less than 5.0% B: 5.0% or more and less than 10.0% C: 10.0% or more and less than 15.0% D: 15.0% or more

<Evaluation of development streaks under high-temperature and high-humidity environment>
After printing 4,000 sheets in the repeated use test, a solid black image was output, and the occurrence of vertical streaks due to toner fusion to the regulating member, so-called development streaks, was visually checked every 100 sheets. [Evaluation criteria]
A: Not generated even after 2,000 sheets B: Generated after more than 1,000 sheets and 2,000 sheets or less C: Generated after more than 500 sheets and 1,000 sheets or less D: Generated after 500 sheets or less

<Production Example of Magnetic Toner Particles 2>
(Pre-coagulation step)
・Magnetic material dispersion liquid 1 (solid content: 25.0% by mass) 105.0 parts The above materials were placed in a beaker, the temperature was adjusted to 30.0°C, and then a homogenizer (Ultra Turrax T50, manufactured by IKA) was used. The mixture was stirred at 5000 rpm for 1 minute, and 1.0 part of a 2.0% by mass magnesium sulfate aqueous solution was gradually added as a flocculating agent and stirred for 1 minute.
(aggregation process)
・Resin particle dispersion 1 (solid content: 25.0% by mass) 150.0 parts ・Wax dispersion 1 (solid content: 25.0% by mass) 15.0 parts was adjusted to 250 parts, and mixed by stirring at 5000 rpm for 1 minute.
Further, 9.0 parts of a 2.0% by mass aqueous solution of magnesium sulfate was gradually added as a flocculating agent.
The raw material dispersion was transferred to a polymerization vessel equipped with a stirrer and a thermometer, heated to 50.0° C. with a mantle heater, and stirred to promote the growth of aggregated particles.
After 59 minutes had passed, 200.0 parts of a 5.0 mass % aqueous solution of ethylenediaminetetraacetic acid (EDTA) was added to prepare an aggregated particle dispersion liquid 2.
Subsequently, after adjusting the aggregated particle dispersion liquid 2 to pH 8.0 using a 0.1 mol/L sodium hydroxide aqueous solution, the aggregated particle dispersion liquid 2 was heated to 80.0° C. and allowed to stand for 180 minutes. Coalescence of agglomerated particles was carried out.
After 180 minutes, a toner particle dispersion liquid 2 in which toner particles are dispersed is obtained. After cooling at a cooling rate of 1.0° C./min, the toner particle dispersion liquid 2 was filtered and washed with ion-exchanged water. Toner particles were removed.
Next, the cake-like toner particles are put into ion-exchanged water of 20 times the mass of the toner particles, stirred with a three-one motor, and when the toner particles are sufficiently loosened, they are filtered again, washed with water, and solidified. Liquid separation occurred. The resulting caked toner particles were pulverized with a sample mill and dried in an oven at 40° C. for 24 hours. Further, the obtained powder was pulverized with a sample mill and then additionally vacuum-dried in an oven at 40° C. for 5 hours to obtain magnetic toner particles 2 .

<Production Examples of Magnetic Toner Particles 3 to 24>
Magnetic toner particles 3, 5, 7 to 9, 11 to 21, and 24 were obtained in the same manner as in the production example of magnetic toner particles 1, except that the conditions were changed to those shown in Table 3.
On the other hand, magnetic toner particles 4, 6, 10, 22 and 23 were obtained in the same manner as in the production example of magnetic toner particles 2, except that the conditions were changed to those shown in Table 3.
In the manufacturing examples of magnetic toner particles 3, 5, 7 and 11, in the first aggregation step, after adding 0.2 parts of a surfactant (Noigen TDS-200, Daiichi Kogyo Seiyaku Co., Ltd.), was added.
In the manufacturing examples of magnetic toner particles 6, 7, 14 and 15, after the first aggregation step to promote the growth of aggregated particles at 50.0° C., the dispersions described in Table 3 were added, again at 50.0° C. A second agglomeration step was carried out to promote the growth of agglomerated particles at 20°C.
In the production examples of magnetic toner particles 20 and 21, after the first aggregation step of promoting the growth of aggregated particles at 50.0°C, the dispersion described in Table 3 was added, and the aggregated particles were again aggregated at 50.0°C. Further, the dispersion described in Table 3 was added, and the third aggregation step was performed again at 50.0° C. to promote the growth of aggregated particles.

<Production Example of Magnetic Toner Particles 25>
・Polyester 1 100.0 parts ・Paraffin wax 4.0 parts (manufactured by Nippon Seiro Co., Ltd., HNP-9)
・ Magnetic substance 1 65.0 parts ・ Charge control agent 1.0 parts (azo iron compound; T-77 (Hodogaya Chemical Industry Co., Ltd.))
The above raw materials were premixed for 2 minutes at 2500 rpm using an FM mixer (FM10C, manufactured by Nippon Coke Kogyo Co., Ltd.). After that, with a twin-screw kneading extruder (PCM-30: manufactured by Ikegai Ironworks Co., Ltd.) set at a rotation speed of 200 rpm, the set temperature was adjusted so that the kneaded material temperature near the outlet of the kneaded material was 150 ° C. and kneaded. .
The obtained melt-kneaded product is cooled, and the cooled melt-kneaded product is coarsely pulverized with a cutter mill. The air temperature was adjusted to 20 kg/hr and the exhaust temperature was adjusted to 38° C., and pulverization was carried out. Further, the magnetic toner particles 25 having a volume average particle size (Dv) of 7.48 μm were obtained by classifying using a multi-division classifier utilizing the Coanda effect.

<Production Example of Magnetic Toner Particles 26>
・Resin particle dispersion 1 (solid content: 20.0% by mass) 150.0 parts ・Wax dispersion 1 (solid content: 25.0% by mass) 15.0 parts ・Magnetic substance dispersion 1 (solid content: 25.0% by mass) %) 35.0 parts The above materials were put into a beaker, and the temperature was adjusted to 30.0°C after adjusting the total number of parts of water to 250 parts. Then, using a homogenizer (manufactured by IKA, Ultra Turrax T50), they were mixed by stirring at 8000 rpm for 10 minutes.
Further, 10.0 parts of a 2.0% by mass aqueous solution of magnesium sulfate was gradually added as a flocculating agent.
The raw material dispersion was transferred to a polymerization vessel equipped with a stirrer and a thermometer, heated to 50.0° C. with a mantle heater, and stirred to promote the growth of aggregated particles.
After 60 minutes had passed, 200.0 parts of a 5.0 mass % aqueous solution of ethylenediaminetetraacetic acid (EDTA) was added to prepare an aggregated particle dispersion liquid 26 .
Subsequently, after adjusting the aggregated particle dispersion 26 to pH 8.0 using a 0.1 mol/L sodium hydroxide aqueous solution, the aggregated particle dispersion 26 is heated to 80.0° C. and left for 180 minutes. Coalescence of agglomerated particles was carried out.
After 180 minutes, a toner particle dispersion liquid 26 in which toner particles are dispersed is obtained. After cooling at a cooling rate of 1.0° C./min, the toner particle dispersion 26 was filtered and washed with ion-exchanged water. Toner particles were removed.
Next, the cake-like toner particles are put into ion-exchanged water of 20 times the mass of the toner particles, stirred with a three-one motor, and when the toner particles are sufficiently loosened, they are filtered again, washed with water, and solidified. Liquid separation occurred. The resulting caked toner particles were pulverized with a sample mill and dried in an oven at 40° C. for 24 hours. Further, the obtained powder was pulverized with a sample mill and then additionally vacuum-dried in an oven at 40° C. for 5 hours to obtain magnetic toner particles 26 .

<Production Example of Magnetic Toner Particles 27>
In the production example of the magnetic toner particles 25, the conditions for preliminary mixing in the FM mixer (FM10C, manufactured by Nippon Coke Kogyo Co., Ltd.) were 1000 rpm for 1 minute, and the kneading conditions in the twin-screw kneading extruder were the rotation speed of 150 rpm, and the Magnetic toner particles 27 were obtained in the same manner except that the temperature of the kneaded material near the outlet was changed to 130.degree.

<Production Example of Magnetic Toner Particles 28>
・Resin particle dispersion 1 (solid content: 20.0% by mass) 150.0 parts ・Wax dispersion 1 (solid content: 25.0% by mass) 15.0 parts ・Magnetic substance dispersion 1 (solid content: 25.0% by mass) %) 105.0 parts The above materials were put into a beaker, and after adjusting the total number of parts of water to 250 parts, the temperature was adjusted to 30.0°C. Then, using a homogenizer (manufactured by IKA, Ultra Turrax T50), they were mixed by stirring at 8000 rpm for 10 minutes.
Further, 0.1 mol/L hydrochloric acid was gradually added to adjust the pH to 5.0, and the mixture was further stirred at 8000 rpm for 20 minutes.
Transfer the raw material dispersion to a polymerization vessel equipped with a stirring device and a thermometer, heat to 50.0° C. with a mantle heater, gradually add 0.1 mol/L hydrochloric acid to adjust the pH to 3.0, and stir. This promoted the growth of aggregated particles.
After 60 minutes have passed, the pH of the aggregated particle dispersion 28 is adjusted to 6.8 using a 0.1 mol/L sodium hydroxide aqueous solution, and then the aggregated particle dispersion 28 is heated to 90.0°C. It was allowed to stand for 180 minutes to coalesce the aggregated particles.
After 180 minutes, a toner particle dispersion liquid 28 in which toner particles are dispersed is obtained. After cooling at a cooling rate of 1.0° C./min, the toner particle dispersion 28 was filtered and washed with ion-exchanged water. Toner particles were removed.
Next, the cake-like toner particles are put into ion-exchanged water of 20 times the mass of the toner particles, stirred with a three-one motor, and when the toner particles are sufficiently loosened, they are filtered again, washed with water, and solidified. Liquid separation occurred. The resulting caked toner particles were pulverized with a sample mill and dried in an oven at 40° C. for 24 hours. Further, the obtained powder was pulverized with a sample mill and then additionally vacuum-dried in an oven at 40° C. for 5 hours to obtain magnetic toner particles 28 .

<Production Example of Magnetic Toner Particles 29>
(Pre-coagulation step)
・Magnetic material dispersion liquid 1 (solid content: 25.0% by mass) 105.0 parts The above materials were placed in a beaker, the temperature was adjusted to 30.0°C, and then a homogenizer (Ultra Turrax T50, manufactured by IKA) was used. The mixture was stirred at 8000 rpm for 10 minutes, and 1.0 part of a 2.0% by mass magnesium sulfate aqueous solution was gradually added as a flocculating agent and stirred for 10 minutes.
(aggregation process)
・Resin particle dispersion 1 (solid content: 25.0% by mass) 150.0 parts ・Wax dispersion 1 (solid content: 25.0% by mass) 15.0 parts was adjusted to 250 parts, and mixed by stirring at 8000 rpm for 1 minute.
Further, 9.0 parts of a 2.0% by mass aqueous solution of magnesium sulfate was gradually added as a flocculating agent.
The raw material dispersion was transferred to a polymerization vessel equipped with a stirrer and a thermometer, heated to 50.0° C. with a mantle heater, and stirred to promote the growth of aggregated particles.
After 50 minutes had passed, 200.0 parts of a 5.0 mass % aqueous solution of ethylenediaminetetraacetic acid (EDTA) was added to prepare an aggregated particle dispersion liquid 29 .
Subsequently, after adjusting the aggregated particle dispersion 29 to pH 8.0 using a 0.1 mol/L sodium hydroxide aqueous solution, the aggregated particle dispersion 29 is heated to 80.0° C. and left for 180 minutes. Coalescence of agglomerated particles was carried out.
After 180 minutes, a toner particle dispersion liquid 29 in which toner particles are dispersed is obtained. After cooling at a cooling rate of 1.0° C./min, the toner particle dispersion 29 was filtered and washed with ion-exchanged water. Toner particles were removed.
Next, the cake-like toner particles are put into ion-exchanged water of 20 times the mass of the toner particles, stirred with a three-one motor, and when the toner particles are sufficiently loosened, they are filtered again, washed with water, and solidified. Liquid separation occurred. The resulting caked toner particles were pulverized with a sample mill and dried in an oven at 40° C. for 24 hours. Further, the obtained powder was pulverized by a sample mill, and then additionally vacuum-dried in an oven at 40° C. for 5 hours to obtain magnetic toner particles 29 .

<Production Example of Magnetic Toner Particles 30 and 31>
Magnetic toner particles 30 and 31 were obtained in the same manner as in the production example of magnetic toner particles 26 except that the conditions were changed to those shown in Table 3.
In the manufacturing example of the magnetic toner particles 30, in the first aggregation step, after adding 0.2 parts of a surfactant (Noigen TDS-200, Daiichi Kogyo Seiyaku Co., Ltd.), the aggregating agent was added.
In the production example of the magnetic toner particles 30, after the first aggregation step of promoting the growth of the aggregated particles at 50.0°C, the dispersion described in Table 3 was added, and the aggregated particles were again heated at 50.0°C. A second agglomeration step was performed to promote the growth of

<Manufacturing Examples of Magnetic Toners 2 to 31>
Magnetic toners 2 to 31 were obtained in the same manner as in the manufacturing example of magnetic toner 1, except that magnetic toner particles 1 were changed to magnetic toner particles 2 to 31.
Table 4 shows the following results for the obtained magnetic toners 2 to 31.
Volume average particle size (Dv), number average particle size (Dn), average brightness in the particle size range of Dn-0.500 or more and Dn+0.500 or less [in the table, simply referred to as average brightness], CV1, CV2/ CV1, the average value of the occupied area ratio of the magnetic substance [indicated as A in the table], the average circularity, the number average diameter of the wax domain [indicated as B in the table].

<Examples 2 to 24 and Comparative Examples 1 to 7>
The same evaluation as in Example 1 was performed using magnetic toners 2 to 31. Table 5 shows the results.

43: cleaner container, 44: cleaning blade, 45: electrostatic latent image carrier, 46: charging roller, 47: toner carrier, 48: toner supply member, 49: developing device, 50: transfer member (transfer roller), 51: Fixing device, 52: Pickup roller, 53: Transfer material (paper), 54: Laser generator, 55: Toner regulating member, 56: Fixing member, 57: Toner, 58: Stirring member, R1, R2 and R3: Direction of rotation

Claims (11)

A magnetic toner having emulsion-aggregated magnetic toner particles containing a binder resin, a wax , a magnetic substance , an aggregating agent and a chelating agent ,
Dn (μm) is the number average particle diameter of the magnetic toner,
CV1 (%) is the coefficient of variation of the luminance dispersion value in the particle size range of Dn−0.500 or more and Dn+0.500 or less of the magnetic toner,
When CV2 (%) is the variation coefficient of the luminance dispersion value in the particle size range of Dn-1.500 or more and Dn-0.500 or less of the magnetic toner,
The CV1 and the CV2 satisfy the relationship of the following formula (1),
the magnetic toner has an average brightness of 30.0 to 60.0 in a particle size range of Dn−0.500 to Dn+0.500;
In a cross section of the magnetic toner using a transmission electron microscope,
A variation coefficient CV3 of an area ratio occupied by the magnetic material is 40.0% or more and 80.0% or less when a cross section of the magnetic toner is divided by a square grid having a side of 0.8 μm. magnetic toner.
CV2/CV1≤1.00 (1) In a cross section of the magnetic toner using a transmission electron microscope,
2. The method according to claim 1, wherein an average value of the occupied area ratio of the magnetic material is 10.0% or more and 40.0% or less when the cross section of the magnetic toner is divided by a square grid having a side of 0.8 μm. magnetic toner. 3. The magnetic toner according to claim 1, wherein the CV1 is 1.00% or more and 4.00% or less. 4. The magnetic toner according to claim 1, wherein the wax forms domains inside the emulsion aggregation magnetic toner particles, and the number average diameter of the domains is 50 nm or more and 500 nm or less. The magnetic toner according to any one of claims 1 to 4, wherein the magnetic toner has an average circularity of 0.960 or more. In a cross section of the emulsion aggregation magnetic toner particles using a transmission electron microscope,
Ws is the area percentage occupied by the wax in the region within 1.0 μm from the contour of the cross section,
When the wax occupied area percentage in the internal region inside 1.0 μm from the contour of the cross section is Wc,
The Ws is 1.5% or more and 18.0% or less,
The magnetic toner according to any one of claims 1 to 5, wherein the ratio of Wc to Ws is 2.0 or more and 10.0 or less. The magnetic toner according to any one of claims 1 to 6, wherein the magnetic toner has a number average particle diameter (Dn) of 3.0 µm or more and 7.0 µm or less. The magnetic toner according to any one of claims 1 to 7, wherein the content of the magnetic substance in the magnetic toner is 35% by mass or more and 50% by mass or less. The magnetic toner according to any one of claims 1 to 8, wherein CV2/CV1 is 0.70 or more and 0.95 or less. a charging step of externally applying a voltage to the charging member to charge the electrostatic latent image carrier;
a latent image forming step of forming an electrostatic latent image on the charged electrostatic latent image carrier;
a developing step of developing the electrostatic latent image with toner carried on a toner carrier to form a toner image on the electrostatic latent image carrier;
a transfer step of transferring the toner image on the electrostatic latent image bearing member to a transfer material with or without an intermediate transfer member;
An image forming method including a fixing step of fixing a toner image transferred to a transfer material by heating and pressurizing means,
The developing step is a one-component contact development method in which the electrostatic latent image bearing member and the toner carried on the toner bearing member are brought into direct contact with each other for development,
An image forming method, wherein the toner is the magnetic toner according to any one of claims 1 to 9 . preparing a resin particle dispersion in which resin particles are dispersed in an aqueous medium;
a step of preparing a wax dispersion in which wax is dispersed in an aqueous medium;
a step of preparing a magnetic substance dispersion in which a magnetic substance is dispersed in an aqueous medium;
a mixing step of mixing the resin particle dispersion, the wax dispersion and the magnetic substance dispersion;
After the mixing step, an aggregating step of aggregating the resin particles, the wax and the magnetic material to obtain aggregated particles, and
After the aggregation step, a coalescing step of heating the aggregated particles to unite the resin particles, the wax, and the magnetic material constituting the aggregated particles,
A method for producing a magnetic toner comprising
The aggregation step includes adding an aggregating agent to the mixed solution obtained in the mixing step to aggregate the resin particles, the wax, and the magnetic material, and then adding a chelating agent to stop aggregation and aggregate the particles. is a step of obtaining
A method for producing a magnetic toner, wherein the magnetic toner to be obtained is the magnetic toner according to any one of claims 1 to 9.

Images