JP4332463B2 - Two-component developer - Google Patents

Description

  The present invention relates to a magnetic carrier and a two-component developer used in electrophotography, electrostatic recording method, and electrostatic printing method.

  Conventionally, in an image forming apparatus using an electrophotographic method such as a printer or a copying machine, a two-component developer containing a toner and a magnetic carrier is suitably used from the viewpoint of image quality, durability, and high-speed compatibility. As a method of developing such a two-component developer, in order to ensure a sufficient image density and to improve the reproducibility of fine lines, a magnetic brush of the developer is brought into contact with the photoreceptor, and the peripheral speed of the photoreceptor is increased. In contrast, a developing method is used in which the circumferential speed of the developing sleeve is increased and the alternating electric field and the DC electric field are superimposed.

  As a magnetic carrier used in such a contact two-component developing method, a core particle surface such as ferrite or magnetite coated with an insulating resin is used. This is because the magnetic carrier has a certain level of pressure resistance against the applied electric field. However, since the magnetic carrier coated with insulating resin is insulated, it does not work as a developing electrode during development, and an edge effect appears between halftone and solid black, resulting in image defects such as so-called white spots There is.

  In order to improve this image defect and stabilize the charging of the toner for a longer period of time, a proposal has been made to disperse resin fine particles containing conductive powder in the coating resin (see, for example, Patent Document 1). Furthermore, a proposal has been made to use a coating material in which resin fine particles and a conductive material are dispersed in a resin having a critical surface tension of 35 dyne / cm or less (for example, see Patent Document 2).

  However, these magnetic carriers can suppress image defects and prevent the surface of the magnetic carrier from being contaminated (spent). However, since the ferrite particles are used as the core particles, the developer magnetic field is used in the contact two-component development. The brush marks are likely to be uneven, and there may be a problem that the toner is deteriorated due to the stress on the toner when the low-consumption printing is continued and the toner is separated from the magnetic carrier.

  Therefore, a proposal has been made to use a magnetic material-dispersed carrier with reduced magnetic force and increased resistance (see, for example, Patent Document 3). Furthermore, a proposal has been made to prevent toner spent by coating the surface of a magnetic material dispersion type carrier with a resin having an aminosilane coupling agent, a fluoroalkyl unit, or a unit such as a methylene unit (see, for example, Patent Document 4). ).

These methods have high carrier resistivity, prevent image defects such as white spots by counter-rotating the developing sleeve and photoconductor with a relatively low magnetic force carrier, and have excellent dot reproducibility at high image density. Furthermore, carrier contamination is improved. However, when the process speed is further increased due to further increase in speed, the rubbing force of the developer magnetic brush on the photosensitive member in the development region becomes strong, and the developer may be deteriorated. In addition, the development method in which the developing sleeve and the photosensitive member are rotated counter-rotating is more effective than the developing method in which the developing sleeve and the photosensitive member are rotated in the forward direction. Unevenness (hereinafter referred to as scavenging) may easily occur. In addition, the development amount (image density) and the change in the development amount with respect to the gradation of the potential (gamma curve) are changed due to changes in the distance between the developing sleeve and the photosensitive member, the alternating electric field strength, the amount of developer carried on the developing sleeve, and the like. Easy to change.
JP-A-10-307429, page 2-4 Japanese Patent No. 3173374, page 2-6, Table 1 JP-A-9-281807, page 2-8 JP-A-2000-39740, pages 9-15 FIG.

An object of the present invention is to provide a two- component developer that solves the above-mentioned problems.

  That is, an object of the present invention is to provide a magnetic carrier and a two-component development that have no image defects such as white spots, high image density, and excellent dot reproducibility even in a developing method in which a developing sleeve and a photosensitive member are rotated in the forward direction. It is to provide an agent.

  A further object of the present invention is to provide a magnetic carrier and a two-component developer capable of outputting a stable image density image over a long period of time even in low consumption printing.

で示される重量平均分子量５，０００乃至９，０００のメチルメタクリレートマクロマーと、
下記式（４）で示されるユニットを形成するためのパーフルオロアルキルユニットを有するメタクリル酸エステルと、

〔式中、ｍ及びｎはそれぞれ独立して１乃至１０のいずれかの整数を示す。〕
下記式（５）で示されるメタクリル酸エステルユニット又はアクリル酸エステルユニットを形成するためのメタクリル酸エステル又はアクリル酸エステル

〔式中、Ｒ_１は水素原子又はメチル基を示し、Ｒ_２は水素原子又は炭素数１乃至２０のいずれかのアルキル基を示す。〕
とをグラフト共重合したフッ素系樹脂であり、
該コート材は、少なくとも該フッ素系樹脂１００質量部に対して微粒子を１乃至４０質量部及び導電性粒子を１乃至１５質量部含有し、
該コート材量は、磁性体分散樹脂コア１００質量部に対し０．３乃至４．０質量部であり、
該磁性キャリアの接触角が９５乃至１２５°である
ことを特徴とする二成分系現像剤を提供することにある。 Another object of the present invention is to provide a two-component developer containing a toner and a magnetic carrier.
The angle of repose when the toner concentration of the two-component developer is 8% by mass is 30 to 41 °,
The toner comprises toner particles containing a binder resin, a release agent, and a colorant, and silica particles and titanium oxide particles as external additives, and the toner has an aggregation degree of 20 to 90, The magnetic carrier is formed by coating the surface of a magnetic material-dispersed resin core containing at least a magnetic material and a binder resin with a coating material,
The coating material has the following formula

A methyl methacrylate macromer having a weight average molecular weight of 5,000 to 9,000 represented by :
A methacrylic acid ester having a perfluoroalkyl unit for forming a unit represented by the following formula (4) ;

[Wherein, m and n each independently represent an integer of 1 to 10. ]
Methacrylic acid ester or acrylic acid ester for forming a methacrylic acid ester unit or an acrylic acid ester unit represented by the following formula (5)

[Wherein, R ₁ represents a hydrogen atom or a methyl group, and R ₂ represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms. ]
Is a fluorine-based resin obtained by graft copolymerization with
The coating material contains 1 to 40 parts by mass of fine particles and 1 to 15 parts by mass of conductive particles with respect to at least 100 parts by mass of the fluororesin.
The amount of the coating material is 0.3 to 4.0 parts by mass with respect to 100 parts by mass of the magnetic material-dispersed resin core.
An object of the present invention is to provide a two-component developer characterized in that the contact angle of the magnetic carrier is 95 to 125 °.

  INDUSTRIAL APPLICABILITY The present invention can provide a magnetic carrier and a two-component developer that are free from image defects such as white spots, have high image density, and are excellent in dot reproducibility even when developing with a developing sleeve and a photoreceptor rotated in the forward direction. .

  In addition, the magnetic carrier and the two-component developer of the present invention can output a stable image density image for a long time even in low consumption printing.

  The inventors have coated the surface of a magnetic material-dispersed resin core with a coating material in which a fluorine resin having a high releasability from toner and fine particles having a particle size of a certain degree or more are dispersed in the fluorine resin. By doing so, the surface roughness of the magnetic carrier and the releasability were controlled. This improves toner separation during development and can improve image defects such as white spots even when the magnetic carrier has a high resistance in the developing method in which the developing sleeve and the photoreceptor rotate in the forward direction.

  Next, white spots will be described with reference to FIG. FIG. 2 shows an enlarged view (2-1) of an image in which an actual white spot is generated, a schematic diagram (2-2) of a cross section of a toner layer that forms an image at that time, and an ideal state (a white spot is shown). (2-3) is shown. (2-1) is a developing method in which the developing sleeve and the photosensitive member are rotated in the forward direction in the developing region and developed, and the developing direction of the toner is developed from the left in the order of the halftone portion, the solid portion, and the halftone portion. It is an image. A portion that is white between the left halftone portion and the solid black portion is referred to as “white spot” in the present invention. (2-2) schematically shows a cross section of the image viewed from the side. In the figure, reference numeral 21 denotes a transfer material, and reference numeral 22 denotes a cross section of the toner layer. In FIG. 2, A is a white portion, and the toner layer is lost in the boundary region between the halftone portion and the solid portion. Also, a so-called “sweeping” phenomenon (B in FIG. 2) in which the toner layer becomes higher appears at the boundary between the solid portion and the halftone portion where the development is performed next. Since “white spots” and “sweeping” occur by the same mechanism, the white spots will be described in detail here.

  Image defects such as white spots are caused by the wrapping of lines of electric force from the developing sleeve to the photosensitive member at the developing pole. When the resistance of the magnetic carrier is low to some extent, the magnetic carrier plays the role of an electrode, and an electrode is apparently present in the vicinity of the photoreceptor pole, and the wraparound of the electric lines of force can be suppressed, so that the edge effect is unlikely to appear. . However, when the magnetic carrier has a high resistance, an electric field is applied between the photosensitive member and the developing sleeve (several hundred μm), so that the lines of electric force swell around the nearest part. Therefore, the counter charge on the surface of the magnetic carrier remains after the toner flies from the magnetic carrier by development at the rear end of the developing nip (the portion where the developer is in contact with the photosensitive member), and the magnetic carrier has a high resistance. It is considered that white spots occur due to the developed toner being pulled back by the counter charge. Therefore, for white spots, lowering the resistance of the magnetic carrier serves to suppress the wraparound of the electric lines of force as much as possible because the carrier acts as an electrode and to leak residual charges on the surface of the magnetic carrier after development. It is conceivable to improve. However, there is a case where the latent image is disturbed by rubbing the photoconductor, and the halftone portion is cluttered. In addition, even when a high-resistance magnetic carrier is used, when the developing sleeve and the photoconductor perform development in the counter direction, the magnetic carrier after development may be instantly separated from the development area, so that the toner is not pulled back. found. However, since the peripheral speed difference is too large with respect to the photosensitive member, scavenging (unevenness) due to the magnetic brush may occur.

  Furthermore, it has been found that it is effective to develop a sufficient amount of toner with respect to the latent image potential for white spots. This is presumably because the wraparound of the electric lines of force is eliminated by eliminating the potential difference between the halftone and the solid image portion. When a magnetic carrier having a magnetic material-dispersed resin core is used, developability that sufficiently satisfies the latent image potential is important in development in the forward direction. For this reason, the magnetic carrier is made of a highly releasable fluorine-based resin, and the surface of the surface is made uneven so that the toner can be sufficiently separated from the magnetic carrier. Without disturbing the latent image of the photoreceptor, scavenging is suppressed and a high-quality image can be obtained.

  The magnetic carrier of the present invention preferably has an average particle size of 10 to 80 μm in the particle size distribution based on the number of magnetic carriers. Magnetic carriers having an average particle size of less than 10 μm are likely to adhere to the carrier. If the thickness exceeds 80 μm, the specific surface area of the toner may be small, and good charging may not be possible. In particular, in order to improve image quality and prevent carrier adhesion, the thickness is more preferably 15 to 60 μm, and further preferably 20 to 45 μm.

The magnetic carrier of the present invention has a magnetization intensity (σ1000) of 15 to 65 Am ² / kg (emu / g) measured under a magnetic field of 1000 × (10 ³ / 4π) · A / m (1000 oersted). More preferably, it is 20 to 50 Am ² / kg. When the strength of magnetization (σ1000) exceeds 65 Am ² / kg, the stress on the toner in the developer magnetic brush increases, the toner deteriorates, and the spent on the carrier is likely to occur. . Further, when the magnetization intensity (σ1000) is less than 15 Am ² / kg, the magnetic binding force to the sleeve is lost, and the magnetic carrier adheres and adheres to the surface of the photoreceptor, which may cause a defect in the image.

The magnetic carrier of the present invention preferably has a true specific gravity of 2.5 to 4.0 g / cm ³ , more preferably 3.0 to 3.8 g / cm ³ . When the true specific gravity is within this range, the load on the toner is small in the stirring and mixing of the magnetic resin carrier and the toner, the toner spent on the magnetic carrier is suppressed, and the adhesion of the magnetic carrier to the photoreceptor is suppressed. preferable.

The magnetic carrier of the present invention preferably has a specific resistance of 1 × 10 ^{10 to} 1 × 10 ¹⁴ Ω · cm. When it is less than 1 × 10 ¹⁰ Ω · cm, white spots are improved, but the latent image of the minute dots is disturbed, resulting in poor halftone reproducibility. Further, if it exceeds 1 × 10 ¹⁴ Ωcm, image defects such as an edge effect may occur in the forward development method even if the toner on the surface of the magnetic carrier is as much as possible.

  In the magnetic carrier of the present invention, the contact angle of the magnetic carrier is 95 to 125 °, preferably 105 to 125 °. If the contact angle of the magnetic carrier is less than 95 °, the toner agent cannot be sufficiently separated only by the surface irregularities, and white spots may occur. When the angle exceeds 125 °, white spots are improved and developability is improved. On the other hand, when the developing sleeve is rotated at a high speed, toner scattering occurs and the inside of the machine may be contaminated.

  Specific examples of the fluororesin that forms the coating material used in the magnetic carrier of the present invention include perfluoropolymers such as polyvinyl fluoride, polyvinylidene fluoride, polytrifluoroethylene, and polyfluorochloroethylene, and polytetrafluoroethylene. , Polyperfluoropropylene, copolymer of vinylidene fluoride and acrylic monomer, copolymer of vinylidene fluoride and trifluorochloroethylene, copolymer of tetrafluoroethylene and hexafluoropropylene, vinyl fluoride And a copolymer of vinylidene fluoride, a copolymer of vinylidene fluoride and tetrafluoroethylene, etc., and in particular as a fluorine-based resin forming a coating material preferably used in the present invention,

[Wherein m represents an integer of 1 to 10. ]
It is a polymer or copolymer comprised by the methacrylic acid ester unit or acrylate ester unit which has the perfluoroalkyl unit shown by these.

  The above-mentioned resins can be used alone or in combination. In addition, a curing agent or the like can be mixed with a thermoplastic resin and cured for use.

  In the present invention, when m is 0, it is difficult to satisfy a contact angle of 95 to 125 ° as a magnetic carrier as a coat carrier, and when it exceeds 10, the resin is likely to be precipitated from a solvent and coats. In this case, it is difficult to obtain a good coating film. It is more preferable that m is 5 to 9 in order to have good toner releasability and coat film-forming property.

  More preferably, it is excellent in adhesiveness with a core by using resin which has a following formula (2).

[Wherein, m and n each independently represent an integer of 1 to 10. ]

  Furthermore, a resin having a unit represented by the following formula (3) is preferable.

[Wherein, m and n each independently represent an integer of 1 to 10, and Z represents a hydrogen atom or a substituted or unsubstituted alkyl group. ]
Z in the above formula (3) is preferably a methyl group.

  Further, a resin having a unit represented by the following formula (4) and a methacrylic acid ester unit or an acrylic acid ester unit represented by the following formula (5) is preferable for separating the toner from the magnetic carrier.

[In formula, m and n are synonymous with the said Formula (3). ]

[Wherein, R ₁ represents a hydrogen atom or a methyl group, and R ₂ represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms. ]

  Further, even when a resin obtained by graft copolymerization of the copolymer units of the above formulas (4) and (5) and a macromonomer such as methyl methacrylate having a molecular weight of about 2000 to 20,000 is used for a long time, the toner separation characteristics are maintained. It is particularly preferable.

  When a thermoplastic resin is used as the fluororesin forming the carrier coating material, this thermoplastic resin has a weight average molecular weight of 20, in a gel permeation chromatograph (GPC) of a soluble component of tetrahydrofuran (THF). 000 to 300,000 is preferable in terms of enhancing the strength of the coating layer, the adhesion between the coating layer and the magnetic core particles, and the adhesion of the thermoplastic resin to the magnetic core particles.

  The fluororesin forming the coating material preferably has a main peak in the molecular weight range of 2,000 to 100,000 in the GPC chromatogram of the THF soluble component, and further has a molecular weight of 2,000 to 100,000. It is preferable to have a subpeak or shoulder in the region of 000. Most preferably, the fluororesin forming the coating material has a main peak in the molecular weight range of 20,000 to 100,000 in the GPC chromatogram of the THF soluble component, and a molecular weight of 2,000 to 19,000. It is preferable to have a sub-peak or shoulder in the region. By satisfying the above molecular weight distribution, the development durability capable of developing a large number of sheets even with a toner having a small particle diameter, the charging stability to the toner, and the prevention of adhesion of the external additive to the surface of the carrier particles are achieved. Further improve.

  When the fluororesin forming the coating material is a graft polymer, the weight average molecular weight of the graft polymer trunk is 15,000 to 200,000, and the weight average molecular weight of the branches is 3,000 to It is preferable that it is 10,000. The weight average molecular weight can be adjusted by the polymerization conditions of the trunk portion of the graft polymer and the polymerization conditions of the branch portion of the graft polymer.

  Further, it is necessary for the coating material to contain fine particles at a ratio of 1 to 40 parts by mass with respect to 100 parts by mass of the fluororesin in order to control the unevenness of the carrier surface and improve the toner separation. . As the fine particles, both organic and inorganic fine particles can be used. However, it is necessary to maintain the shape of the particles when the carrier is coated, and preferably, crosslinked resin particles or inorganic fine particles are preferably used. Can do. Specifically, a crosslinked polymethyl methacrylate resin, a crosslinked polystyrene resin, a melamine resin, a phenol resin, a nylon resin, and inorganic fine particles can be used alone or in combination from silica, titanium oxide, alumina, and the like. In particular, it is preferable to use silica, titanium oxide, alumina, or the like alone or in combination in order to improve the releasability from the toner. Further, silica obtained by the following sol-gel method is particularly preferable in order to obtain durability of the coat layer in order to improve the releasability from the toner and the toner chargeability over a long period of time.

  The fine particles preferably have a maximum peak value of 80 to 600 nm, and more preferably 100 to 500 nm, in the particle size distribution based on the number of fine particles. By using fine particles having such a maximum peak value, although depending on the coating amount, irregularities on the surface of the magnetic carrier can be formed, and toner separation can be improved. Among the fine particles, silica produced by the sol-gel method is preferable in that the particle size distribution is very sharp, uniform irregularities can be formed, and toner separation and long-term surface releasability are obtained. The sol-gel method may be a generally used synthesis process, and water and alcohol are added to a raw material alkoxide to form particles having a uniform particle size by dispersing the particles in a liquid called “sol”. The sol is hydrolyzed into a transparent “gel”, which can be obtained by drying and heat treatment to remove alcohol and moisture.

  In the magnetic carrier of the present invention, it is preferable to use 1 to 40 parts by mass of the fine particles with respect to 100 parts by mass of the fluororesin, and more preferably 1 to 40 parts of the fine particles with respect to 100 parts by mass of the fluororesin. In addition to parts by mass, it is preferable to use 1 to 15 parts by mass of conductive particles in order to reduce the specific resistance of the magnetic carrier and to remove residual charges on the surface of the magnetic carrier.

The conductive particles preferably have a specific resistance of 1 × 10 ⁸ Ωcm or less, and more preferably have a specific resistance of 1 × 10 ⁶ Ωcm or less. The conductive particles are preferably particles containing at least one kind of particles selected from carbon black, magnetite, graphite, titanium oxide, alumina, zinc oxide, and tin oxide. In particular, as the conductive particles, carbon black can be preferably used without inhibiting the irregularities caused by the fine particles on the surface of the carrier having a small particle size. The conductive particles preferably have a maximum peak value of 10 to 60 nm, more preferably 15 to 50 nm, in the particle size distribution on the basis of the number. The maximum peak value of the conductive particles is preferably 10 nm to 60 nm in order to remove the residual charge on the surface of the carrier satisfactorily and to prevent detachment from the carrier satisfactorily.

  The amount of the coating material of the resin forming the coating layer is 0.3 to 4.0 parts by mass with respect to 100 parts by mass of the magnetic material-dispersed resin core, in order to obtain the effect of surface unevenness due to the fine particles. . If the amount is less than 0.3 parts by mass, the fine particles cannot be retained, and there may be a problem that the fine particles fall off. If the amount exceeds 4.0 parts by mass, uniform coating may not be possible during coating, and charge up and the core surface may be exposed, resulting in toner spent at that portion. In order to obtain good toner separation, the amount is preferably 0.5 to 3.5 parts by mass.

  The magnetic material-dispersed resin core used in the magnetic carrier of the present invention is made of oxidized iron powder or unoxidized iron powder, iron, lithium, calcium, magnesium, nickel, copper, zinc, cobalt, manganese, chromium In addition, a magnetic material-dispersed resin core containing metal particles such as rare earths, alloy particles thereof, oxide particles, magnetite, and a binder resin that holds a magnetic material such as ferrite in a dispersed state, a so-called resin core can be used.

  Examples of the binder resin include vinyl resins having a methylene unit in the polymer chain, polyester resins, epoxy resins, phenol resins, urea resins, polyurethane resins, polyimide resins, cellulose resins, and polyether resins. These resins may be used as a mixture.

  Examples of vinyl monomers for forming the vinyl resin include styrene; o-methylstyrene, m-methylstyrene, p-methylstyrene, p-phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p- n-butyl styrene, p-tert-butyl styrene, pn-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene, p-methoxy Styrene derivatives such as styrene, p-chlorostyrene, 3,4-dichlorostyrene, m-nitrostyrene, o-nitrostyrene, p-nitrostyrene; ethylene and unsaturated monoolefins such as ethylene, propylene, butylene, isobutylene; Unsaturated diolefins such as butadiene and isoprene; vinyl chloride, salts Vinyl halides such as vinylidene, vinyl bromide, vinyl fluoride; vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzoate; methacrylic acid; methyl methacrylate, ethyl methacrylate, propyl methacrylate, methacrylic acid-n- Α-methylene aliphatic monocarboxylic esters such as butyl, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate; acrylic acid; methyl acrylate, Ethyl acrylate, acrylic acid-n-butyl, isobutyl acrylate, propyl acrylate, acrylic acid-n-octyl, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, acrylic acid-2-chloro Acrylic acid esters such as ruethyl and phenyl acrylate; maleic acid and maleic acid half esters; vinyl ethers such as vinyl methyl ether, vinyl ethyl ether and vinyl isobutyl ether; vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone and methyl isopropenyl ketone; N-vinyl compounds such as N-vinylpyrrole, N-vinylcarbazole, N-vinylindole, N-vinylpyrrolidone; vinylnaphthalene; acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile, acrylamide; acrolein, etc. . Those obtained by polymerization using one or more of these are used as the vinyl resin.

  As a method for producing magnetic material-dispersed resin core particles, there is a method in which a binder resin monomer and a magnetic material are mixed and the monomer is polymerized to obtain magnetic material-dispersed core particles. At this time, as monomers used for the polymerization, in addition to the vinyl monomers described above, bisphenols and epichlorohydrin for forming epoxy resins; phenols and aldehydes for forming phenol resins; urea resins are formed. For this purpose urea and aldehydes, melamine and aldehydes are used. As a method for producing a magnetic material-dispersed core particle using a curable phenol resin, a magnetic material is placed in an aqueous medium, and phenols and aldehydes are polymerized in the presence of a basic catalyst in the aqueous medium. There is a method for obtaining dispersed core particles.

  As another method for producing the magnetic material-dispersed resin core particles, a vinyl-based or non-vinyl-based thermoplastic resin, a magnetic material, and other additives are sufficiently mixed by a mixer, and then a heating roll, a kneader, and an extruder. There is a method of obtaining magnetically dispersed core particles by melting and kneading using a kneader such as the above, cooling, and then pulverizing and classifying. At this time, it is preferable that the obtained magnetic material-dispersed core particles are thermally or mechanically spheroidized and used as magnetic material-dispersed core particles for the resin carrier. Among the above-mentioned binder resins, thermosetting resins such as phenol resins, melamine resins, and epoxy resins are preferable because they are excellent in durability, impact resistance, and heat resistance. The binder resin is more preferably a phenol resin in order to more suitably express the characteristics of the present invention.

  The carrier of the present invention is used containing a magnetic substance. The amount of the magnetic material used in the resin carrier is 70 to 95% by mass (more preferably 80 to 92% by mass) with respect to the magnetic carrier, so that the true specific gravity of the magnetic carrier is reduced and the mechanical strength is increased. Is preferable for sufficiently ensuring the above. Furthermore, in order to change the magnetic characteristics of the magnetic carrier, it is preferable to add a nonmagnetic inorganic compound to the magnetic material dispersed core particles in addition to the magnetic material. In the present invention, the average particle size in the particle size distribution based on the number of magnetic materials is preferably 20 to 2000 nm.

  In addition, the nonmagnetic inorganic compound has a larger specific resistance value than the magnetic material, and the average particle size in the particle size distribution based on the number of nonmagnetic inorganic compounds is larger than the average particle size in the particle size distribution based on the number of magnetic materials. A larger value is preferable for increasing the specific resistance value of the magnetic carrier. In the present invention, the average particle size in the particle size distribution based on the number of nonmagnetic inorganic compounds is preferably from 50 to 5000 nm.

  The magnetic substance is contained in an amount of 50 to 100% by mass with respect to the total amount of the magnetic substance and the nonmagnetic inorganic compound to adjust the strength of magnetization of the resin carrier to prevent carrier adhesion. It is preferable when adjusting the specific resistance value.

The magnetic carrier used in the present invention is preferably a magnetite fine particle or a magnetic ferrite fine particle containing at least an iron element and a magnesium element, and the nonmagnetic inorganic compound is hematite (α-Fe ₂ O ₃ ) fine particles are more preferable for adjusting the magnetic properties and true specific gravity of the carrier.

  As phenols for producing a phenol resin, in addition to phenol itself, alkylphenols such as m-cresol, p-tert-butylphenol, o-propylphenol, resorcinol, bisphenol A and a part of benzene nucleus or alkyl group or Examples thereof include compounds having a phenolic hydroxyl group such as halogenated phenols, all of which are substituted with chlorine atoms or bromine atoms. Of these, phenol (hydroxybenzene) is more preferable.

  Examples of aldehydes include formaldehyde and furfural in the form of either formalin or paraaldehyde. Of these, formaldehyde is particularly preferable.

  The molar ratio of aldehydes to phenols is preferably 1 to 4, particularly preferably 1.2 to 3. When the molar ratio of aldehydes to phenols is less than 1, particles are difficult to generate, and even if they are generated, the resin does not easily cure, so the strength of the generated particles tends to be weak. On the other hand, when the molar ratio of aldehydes to phenols is larger than 4, unreacted aldehydes remaining in the aqueous medium after the reaction tend to increase.

  Examples of the basic catalyst used in the condensation polymerization of phenols and aldehydes include those used in the production of ordinary resol type resins. Examples of such a basic catalyst include aqueous ammonia, hexamethylenetetramine and alkylamines such as dimethylamine, diethyltriamine, and polyethyleneimine. The molar ratio of these basic catalysts to phenols is preferably 0.02 to 0.3.

  The toner used in the present invention has a weight average particle diameter of 3.0 to 10.0 μm. The weight average particle size of the toner is preferably 4.0 μm to 7.0 μm in order to sufficiently satisfy dot reproducibility and transfer efficiency. If the weight average particle size of the toner is less than 3.0 μm, the specific surface area of the toner becomes large, so that it becomes difficult to control the charge amount, the developability is lowered, and white spots may be deteriorated. When the weight average particle diameter of the toner exceeds 10.0 μm, the dot reproducibility is poor and there is a problem in improving the image quality. The weight average particle diameter of the toner can be adjusted by classification of the toner particles at the time of production, mixing of classified products, or the like.

  The magnetic carrier and the toner of the present invention can be mixed and used in a form having a specific surface area. The toner concentration is preferably about 4% by mass to 12% by mass with respect to the two-component developer in consideration of charging amount application, fogging, image density, white spot prevention, and the like. The angle of repose when the toner concentration of the two-component developer mixed with the toner and the magnetic carrier is 8% by mass is 30 to 41 °, which suppresses the toner scattering while improving the white spots. It is necessary to improve the coexistence. The angle of repose of the developer can be appropriately used by changing the surface properties of the magnetic carrier, the shape of the toner, the type of toner external additive, the amount of external additive, the particle size of the external additive, and the like.

  The average circularity of the toner used in the present invention is preferably 0.925 or more and 0.980 or less in order to achieve both transferability and developability, and more preferably 0.925 or more and 0.950 or less. is there. When the average circularity of the toner is lower than 0.925, the transfer efficiency may be deteriorated. When the average circularity of the toner exceeds 0.980, the transfer efficiency is considerably improved, but as the durability progresses, the toner gradually deteriorates, and when the transfer property is deteriorated, a cleaning defect may easily occur. The average circularity of the toner can be adjusted by a toner particle manufacturing method or a known spheroidizing method by applying a mechanical force or heat to the toner particle.

  The toner of the present invention preferably has a light transmittance of 30 to 80% at a wavelength of 600 nm with respect to a dispersion obtained by dispersing the toner in a 45 volume% methanol aqueous solution. Further, the transmittance is preferably 40 to 65% from the viewpoint of improving toner separation from the magnetic carrier and preventing white spots even in durability.

  Because the wettability of the binder resin and the release agent is different, when the toner is dispersed in a water-methanol solution, the water in which the toner is dispersed is different depending on the presence state of the release agent in the vicinity of the surface of the toner particles. The concentration of the methanol solution becomes different. In the present invention, by utilizing this property and measuring the transmittance, it is used as an indicator of the state of presence of the release agent near the surface of the toner particles. Further, in the present invention, when a methanol aqueous solution having a methanol content of around 45% by volume is used, the sensitivity to the difference in wettability between the binder resin and the release agent is good. Volume% + water 55 volume%).

  The transmittance of the toner in a 45 volume% methanol aqueous solution may become a large value when the particle size of the toner is decreased and the surface area of the toner is increased. In particular, in a toner having a small particle size such as a weight average particle size of 7.0 μm or less, the state of the toner surface is easily affected by the dispersion state of the release agent and the dispersed particle size, and even with a slight dispersion failure, The transmission varies greatly. The transmittance increases when there is a large amount of release agent near the surface of the toner particles, or when a large amount of release agent clogs up on the surface of the toner particles due to poor dispersion of the release agent. This is presumably because, in the case described above, the wettability of the toner with respect to the water-methanol solution deteriorates, and the toner becomes difficult to disperse.

  If the transmittance is less than 30%, the amount of the release agent present in the vicinity of the surface of the toner particles is small, the developability after durability is good, and the white spots are very good, but the low temperature fixability and Gloss may be reduced. When the transmittance exceeds 80%, the low-temperature fixability is improved, but the release agent is released from the toner, migrates to the surface of the developing sleeve and the magnetic carrier, becomes contaminated, and developability decreases with durability. White spots may also worsen.

  The transmittance is determined by controlling the temperature and time of pulverization and shape adjustment during the production of toner particles, the conditions of the type of release agent used and the type of dispersant of the release agent, and controlling the conditions of the release agent on the toner surface. It can be adjusted by controlling the presence state. The transmittance can be measured using a spectrophotometer.

  To the toner particles of the present invention, fine particles are externally added for the purpose of improving fluidity, transferability, particularly toner separation and improving white spots. One of the external additives externally added to the toner particle surface is preferably inorganic fine particles. The inorganic fine particles preferably include at least one of titanium oxide, alumina oxide, and silica. The inorganic fine particles preferably have a maximum peak value in the range of 80 nm to 200 nm in the particle size distribution based on the number of the inorganic fine particles in order to function as spacer particles for improving the toner separation from the carrier. The external additive is preferably used in combination with fine particles having a maximum peak value of 50 nm or less in the particle size distribution based on the number of external additives in order to improve toner fluidity. As an index, in the present invention, the degree of toner aggregation is preferably 20 to 90 in order to achieve both toner separation and transferability when converted into a developer, and more preferably 30 to 70. If it is less than 20, problems such as toner scattering and scattering during transfer are likely to occur. If it exceeds 90, it becomes difficult to mix the toner and the magnetic carrier, and problems such as fogging due to poor charging are likely to occur.

  Further, when the toner concentration of the two-component developer is 8% by mass, the angle of repose is 30 to 41 °, so that the toner is well separated even after long-term use and an image free from image defects such as white spots is obtained. Preferred above. More preferably, the angle is 30 to 38 °. If the angle is less than 30 °, it may cause problems such as toner scattering. If it exceeds 41 °, toner separation from the magnetic carrier is worsened and white spots occur, and the developer may be bridged in the developing unit and the developer may not be conveyed to the developing electrode.

  The toner used in the present invention is preferably a toner particle having a binder resin, a colorant, and a release agent, and a toner used for oilless fixing having an external additive. The binder resin includes a polyester unit, The mold agent is a hydrocarbon-based wax, and has one or more endothermic peaks in the temperature range of 30 to 200 ° C. in the endothermic curve in the differential thermal analysis measurement of the toner, and the maximum endotherm in the endothermic peak. A toner having a peak temperature of 65 ° C. to 110 ° C. can be preferably used because the degree of aggregation of the toner is appropriately increased to improve transferability and image defects such as white spots can be improved.

  In the present invention, the “polyester unit” refers to a portion derived from polyester, and the polyester monomer constituting the polyester unit includes a polyhydric alcohol, a polycarboxylic acid, a polycarboxylic anhydride, or two or more. A carboxylic acid component such as a polycarboxylic acid ester having a carboxyl group can be used as a raw material monomer.

  As the dihydric alcohol component, polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene (3.3) -2,2-bis (4-hydroxyphenyl) propane , Polyoxyethylene (2.0) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene (2.0) -polyoxyethylene (2.0) -2,2-bis (4-hydroxy) Phenyl) propane, polyoxypropylene (6) -2,2-bis (4-hydroxyphenyl) propane-like alkylene oxide adducts such as ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1 , 3-propylene glycol, 1,4-butanediol, neopentylglycol 1,4-butenediol, 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, bisphenol A, Examples include compounds such as hydrogenated bisphenol A.

  Examples of trihydric or higher alcohol components include sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butanetriol, 1 , 2,5-pentanetriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, 1,3,5-trihydroxymethylbenzene Is mentioned.

  Examples of the carboxylic acid component include aromatic dicarboxylic acids such as phthalic acid, isophthalic acid and terephthalic acid or anhydrides thereof; alkyl dicarboxylic acids such as succinic acid, adipic acid, sebacic acid and azelaic acid or anhydrides thereof; And succinic acid substituted with 12 to 12 alkyl groups or anhydrides thereof; unsaturated dicarboxylic acids such as fumaric acid, maleic acid and citraconic acid or anhydrides thereof;

  The polyester resin has a bisphenol derivative represented by the following formula (6) as an alcohol component, and a carboxylic acid component (for example, fumaric acid) composed of a divalent or higher carboxylic acid or an acid anhydride thereof or a lower alkyl ester thereof. , Maleic acid, maleic anhydride, phthalic acid, terephthalic acid, dodecenyl succinic acid, trimellitic acid, pyromellitic acid, etc.), and a polyester resin obtained by condensation polymerization of these components has good charging characteristics as a color toner. Therefore, it is preferable.

[Wherein, R ₃ and R ₄ are each independently one or more selected from an ethylene group and a propylene group, x and y are each independently an integer of 1 or more, and x + y is 2 to 10. . ]

  Examples of the trivalent or higher polyvalent carboxylic acid component for forming a polyester resin having a crosslinking site include 1,2,4-benzenetricarboxylic acid, 1,2,5-benzenetricarboxylic acid, 1,2,4. -Naphthalene tricarboxylic acid, 2,5,7-naphthalene tricarboxylic acid, 1,2,4,5-benzenetetracarboxylic acid, and acid anhydrides and ester compounds thereof. The use amount of the trivalent or higher polyvalent carboxylic acid component is preferably 0.1 to 1.9 mol% based on the total monomers.

  In the present invention, (a) a polyester resin, (b) a hybrid resin having a polyester unit and a vinyl polymer unit, (c) a mixture of the hybrid resin and the vinyl polymer, (d) a polyester Use a resin selected from a mixture of a resin and a vinyl polymer, (e) a mixture of a hybrid resin and a polyester resin, and (f) a mixture of a polyester resin, a hybrid resin, and a vinyl polymer. Is preferred.

  Examples of the mold release agent used in the present invention include low molecular weight polyethylene, low molecular weight polypropylene, low molecular weight olefin copolymer, aliphatic hydrocarbon wax such as microcrystalline wax, paraffin wax, and Fischer-Tropsch wax; Oxides of aliphatic hydrocarbon waxes; waxes based on fatty acid esters such as aliphatic hydrocarbon ester waxes; and fatty acid esters such as deoxidized carnauba wax that are partially or fully deoxidized . Furthermore, a partially esterified product of a fatty acid such as behenic acid monoglyceride and a polyhydric alcohol; a methyl ester compound having a hydroxyl group obtained by hydrogenating vegetable oils and the like. Particularly preferred waxes are aliphatic hydrocarbon waxes such as paraffin wax, polyethylene wax, and Fischer-Tropsch wax that have a short molecular chain and little steric hindrance and excellent mobility.

  The toner used in the present invention has one or more endothermic peaks in the temperature range of 30 to 200 ° C. in the endothermic curve in differential thermal analysis (DSC) measurement, and the maximum endothermic peak temperature Tsc is 65 ° C. ≦ Tsc ≦ 110 ° C. is preferable, and 70 ° C. ≦ Tsc ≦ 90 ° C. is more preferable. If the temperature of the maximum endothermic peak is less than 65 ° C., the release agent may ooze out to the toner surface, the toner aggregation degree may be increased, and white spots may easily occur. May be inferior. The maximum endothermic peak refers to an endothermic peak that is the maximum from the base line in the endothermic peak in a region equal to or higher than the endothermic peak derived from the glass transition temperature of the binder resin. The temperature of the maximum endothermic peak can be adjusted depending on the type of the release agent used.

  The release agent used in the present invention preferably has a content of 1 to 10 parts by mass, and more preferably 2 to 8 parts by mass with respect to 100 parts by mass of the binder resin. If the content is less than 1 part by mass, the releasability may not be exhibited well at the time of oilless fixing, or the low temperature fixing property may not be satisfied. When it exceeds 10 parts by mass, the release agent tends to ooze out on the surface of the toner, and white spots may be deteriorated.

  The toner of the present invention can be used in combination with a known charge control agent. Examples of such charge control agents include organometallic complexes, metal salts, chelate compounds, and metal complexes such as monoazo metal complexes, acetylacetone metal complexes, hydroxycarboxylic acid metal complexes, polycarboxylic acid metal complexes, and polyol metal complexes. . Other examples include carboxylic acid derivatives such as metal salts of carboxylic acids, carboxylic acid anhydrides, and esters, and condensates of aromatic compounds. As the charge control agent, phenol derivatives such as bisphenols and calixarenes are also used. In the present invention, it is preferable to use a metal compound of an aromatic carboxylic acid in order to improve the rising of charging.

  In the present invention, the charge control agent preferably has a content of 0.1 to 10 parts by mass, more preferably 0.2 to 5 parts by mass with respect to 100 parts by mass of the binder resin. If the amount is less than 0.1 parts by mass, the change in the charge amount of the toner in an environment from high temperature and high humidity to low temperature and low humidity may become large. If the amount is more than 10 parts by mass, the toner may be inferior in low-temperature fixability.

  As the colorant used in the present invention, known pigments and dyes can be used alone or in combination. Examples of the dye include C.I. I. Direct Red 1, C.I. I. Direct Red 4, C.I. I. Acid Red 1, C.I. I. Basic Red 1, C.I. I. Modern Tread 30, C.I. I. Direct Blue 1, C.I. I. Direct Blue 2, C.I. I. Acid Blue 9, C.I. I. Acid Blue 15, C.I. I. Basic Blue 3, C.I. I. Basic Blue 5, C.I. I. Modern Blue 7, C.I. I. Direct Green 6, C.I. I. Basic Green 4, C.I. I. A dye such as Basic Green 6 may be mentioned.

  As pigments, mineral fast yellow, navel yellow, naphthol yellow S, hansa yellow G, permanent yellow NCG, tartrazine lake, molybdenum orange, permanent orange GTR, pyrazolone orange, benzidine orange G, permanent red 4R, watch red red calcium salt , Eosin Lake, Brilliant Carmine 3B, Manganese Purple, Fast Violet B, Methyl Violet Lake, Cobalt Blue, Alkaline Blue Lake, Victoria Blue Lake, Phthalocyanine Blue, Fast Sky Blue, Indanthrene Blue BC, Chrome Green, Pigment Green B, Examples of the pigment include malachite green lake and final yellow green G.

  Further, when used as a full-color image forming toner, examples of the magenta color pigment include C.I. I. Pigment Red 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 21, 22, 23, 30, 31, 32, 37, 38, 39, 40, 41, 48, 49, 50, 51, 52, 53, 54, 55, 57, 58, 60, 63, 64, 68, 81, 83, 87, 88, 89, 90, 112, 114, 122, 123, 163, 202, 206, 207, 209, 238, C.I. I. Pigment violet 19, C.I. I. Examples thereof include pigments such as Vat Red 1, 2, 10, 13, 15, 23, 29, and 35.

  Although such a pigment may be used alone, it is more preferable from the viewpoint of the image quality of a full-color image to improve the sharpness by using a dye and a pigment together. Examples of the magenta dye include C.I. I. Solvent Red 1, 3, 8, 23, 24, 25, 27, 30, 49, 81, 82, 83, 84, 100, 109, 121, C.I. I. Disper thread 9, C.I. I. Solvent Violet 8, 13, 14, 21, 27, C.I. I. Oil-soluble dyes such as Disperse Violet 1; I. Basic Red 1, 2, 9, 12, 13, 14, 15, 17, 18, 22, 23, 24, 27, 29, 32, 34, 35, 36, 37, 38, 39, 40, C.I. I. Basic dyes such as basic violet 1, 3, 7, 10, 14, 15, 21, 25, 26, 27, and 28 may be mentioned.

  Examples of the color pigment for cyan include C.I. I. Pigment Blue 2, 3, 15, 15: 1, 15: 2, 15: 3, 16, 17; I. Acid Blue 6; I. Acid Blue 45 or a copper phthalocyanine pigment in which 1 to 5 phthalimidomethyl groups are substituted on the phthalocyanine skeleton.

  Examples of the color pigment for yellow include C.I. I. Pigment Yellow 1, 2, 3, 4, 5, 6, 7, 10, 11, 12, 13, 14, 15, 16, 17, 23, 65, 73, 74, 83, 93, 97, 155, 180, C. I. Examples thereof include pigments such as Vat Yellow 1, 3, and 20.

  As the black pigment, carbon black such as furnace black, channel black, acetylene black, thermal black and lamp black is used, and magnetic powder such as magnetite and ferrite is also used.

  The amount of the colorant used is preferably 1 to 15 parts by mass, more preferably 3 to 12 parts by mass, and still more preferably 4 to 10 parts by mass with respect to 100 parts by mass of the binder resin. . When the content of the colorant is more than 15 parts by mass, the transparency is lowered, and in addition, the reproducibility of intermediate colors as typified by human skin color is likely to be lowered, and further, the chargeability of the toner is stabilized. And the low-temperature fixability becomes difficult to obtain. When the content of the colorant is less than 1 part by mass, the coloring power is low, so that a large amount of toner must be used to obtain the density, the dot reproducibility is easily impaired, and a high-quality image with a high image density. Is difficult to obtain.

  A suitable method for measuring physical properties related to the present invention will be described below.

<Measurement of toner particle or toner particle size distribution>
As a measuring device, Coulter Counter TA-II or Coulter Multisizer II (manufactured by Coulter Inc.) is used. As the electrolytic solution, an about 1% NaCl aqueous solution is used. As the electrolytic solution, an electrolytic solution prepared using primary sodium chloride or, for example, ISOTON (registered trademark) -II (manufactured by Coulter Scientific Japan) can be used.

  As a measurement method, 0.1 to 5 ml of a surfactant (preferably alkylbenzenesulfone hydrochloric acid) is added as a dispersant to 100 to 150 ml of the electrolytic aqueous solution, and 2 to 20 mg of a measurement sample is further added. The electrolytic solution in which the sample is suspended is dispersed for about 1 to 3 minutes with an ultrasonic disperser, and the volume and number of the sample are measured for each channel with the measuring device using a 100 μm aperture as the aperture. The volume distribution and the number distribution are calculated. From the volume distribution and number distribution of the obtained sample, the weight average particle diameter of the sample is obtained. As channels, 2.00 to 2.52 μm; 2.52 to 3.17 μm; 3.17 to 4.00 μm; 4.00 to 5.04 μm; 5.04 to 6.35 μm; 6.35 to 8. 00 μm; 8.00 to 10.08 μm; 10.08 to 12.70 μm; 12.70 to 16.00 μm; 16.00 to 20.20 μm; 20.20 to 25.40 μm; 25.40 to 32.00 μm; 13 channels of 32-40.30 μm are used.

<Measurement of average toner circularity>
The average circularity of the toner is measured using a flow type particle image measuring device “FPIA-2100 type” (manufactured by Sysmex Corporation), and is calculated using the following formula.

  Here, the “particle projected area” is the area of the binarized toner particle image, and the “peripheral length of the particle projected image” is the length of the contour line obtained by connecting the edge points of the toner particle image. Define. The measurement uses the perimeter of the particle image when image processing is performed at an image processing resolution of 512 × 512 (pixels of 0.3 μm × 0.3 μm).

  In the present invention, the circularity is an index indicating the degree of unevenness of the toner particles, and is 1.000 when the toner particles are completely spherical. The more complicated the surface shape, the smaller the circularity.

The average circularity C, which means the average value of the circularity frequency distribution, is calculated from the following equation, where the circularity (center value) at the dividing point i of the particle size distribution is c _i and the number of measured particles is m. .

  In addition, “FPIA-2100”, which is a measuring apparatus used in the present invention, calculates the circularity of each particle, and then calculates the average circularity. 1.0 is divided into classes equally divided every 0.01, and the average circularity is calculated using the center value of the division points and the number of measured particles.

  As a specific measuring method, 10 ml of ion-exchanged water from which impure solids have been removed in advance is prepared in a container, and a surfactant, preferably an alkylbenzene sulfonate, is added as a dispersant therein, followed by further measurement. Add 0.02 g of sample and disperse uniformly. As a means for dispersion, an ultrasonic disperser “Tetora 150 type” (manufactured by Nikka Ki Bios Co., Ltd.) is used, and dispersion treatment is performed for 2 minutes to obtain a dispersion for measurement. In that case, it cools suitably so that the temperature of this dispersion may not be 40 degreeC or more. In order to suppress variation in circularity, the installation environment of the apparatus is controlled at 23 ° C. ± 0.5 ° C. so that the in-machine temperature of the flow type particle image analyzer FPIA-2100 is 26 to 27 ° C. Preferably, autofocus is performed using 2 μm latex particles every 2 hours.

  To measure the circularity of the toner particles, the flow type particle image measuring apparatus is used, the concentration of the dispersion is readjusted so that the toner particle concentration at the time of measurement is 3000 to 10,000 particles / μl, and the toner particles are 1000 Measure more than one. After the measurement, using this data, data having an equivalent circle diameter of less than 2 μm is cut to determine the average circularity of the toner particles.

  Furthermore, “FPIA-2100”, which is a measuring apparatus used in the present invention, improves the magnification of the processed particle image as compared with “FPIA-1000” conventionally used for calculating the shape of the toner. Furthermore, the accuracy of toner shape measurement has been improved by improving the processing resolution of the captured image (changed from 256 × 256 to 512 × 512), thereby achieving more reliable capture of fine particles. Therefore, when it is necessary to measure the shape more accurately as in the present invention, the FPIA 2100 that can obtain information on the shape more accurately is more useful.

<Transmissivity in a 45% by volume methanol aqueous solution>
(I) Preparation of toner dispersion An aqueous solution having a volume mixing ratio of methanol: water of 45:55 is prepared. 10 ml of this aqueous solution is placed in a 30 ml sample bottle (Nippon Denka Glass: SV-30), 20 mg of toner is immersed on the liquid surface, and the bottle lid is capped. Then, shake for 5 seconds at 150 reciprocations / minute with a Yayoi-type shaker (model: YS-LD). At this time, the angle of shaking is such that the shaking column moves 15 degrees forward and 20 degrees backward, assuming that the vertical (vertical) of the shaker is 0 degree. And it is shaken once forward and backward once, and when returning to just above, it counts as one reciprocation.

  The sample bottle is fixed to a fixing holder (with the sample bottle lid fixed on the extension at the center of the column) attached to the tip of the column. After removing the sample bottle, the dispersion after standing for 30 seconds is used as a dispersion for measurement.

(Ii) Transmittance (%) measurement The dispersion obtained in (i) was put into a 1 cm square quartz cell, and a spectrophotometer MPS2000 (manufactured by Shimadzu Corporation) was used, and 10 minutes after the cell was put into the apparatus. The light transmittance (%) at a wavelength of 600 nm of the dispersion is determined. The transmittance (%) is obtained by the following formula.
Transmittance (%) = I / I ₀ × 100
(In the formula, I ₀ represents an incident light beam, and I represents a transmitted light beam).

<Measurement of aggregation degree of toner particles>
To measure the degree of aggregation of the toner particles, a powder tester P-100 (manufactured by Hosokawa Micron Corporation) is used, and a sieve is set in the order of 143 μm, 76 μm, and 36 μm from the top on the vibration table. The vibration swing width is set to 0.5 mm, the vibration time is set to 15 seconds, and 5 g of toner is gently put on and vibrated. After stopping vibration, measure the mass remaining on each sieve.
(Amount of toner remaining on upper screen) ÷ 5 (g) × 100... A
(Amount of toner remaining on the middle screen) ÷ 5 (g) × 100 × 0.6... B
(The amount of toner remaining on the lower screen) ÷ 5 (g) × 100 × 0.2... C
a + b + c = calculation degree (%)

<Measurement of triboelectric charge amount of toner>
The triboelectric charge amount of the toner of the present invention can be determined by the following method. First, a developer is prepared by mixing the toner and the magnetic carrier so that the toner mass becomes 5% by mass, and the mixture is mixed for 120 seconds with a tumbler mixer. This developer is put in a metal container having a conductive screen having a 635 mesh (20 μm opening) at the bottom, and sucked with a suction machine, and the mass difference between the developer before and after suction and the capacitor connected to the container Measure the potential accumulated in the. At this time, suction is performed for 2 minutes and the suction pressure is set to 250 mmH ₂ O. From the mass difference, the stored potential, and the capacity of the capacitor, the triboelectric charge amount of the toner is calculated using the following formula.
Q (mC / kg) = (C × V) / (W1-W2)
(W1 is the mass (g) of the developer before suction, W2 is the mass (g) of the developer after suction, C is the capacitance (μF) of the capacitor, and V is accumulated in the capacitor. The expressed potential (V)).

<Measurement of molecular weight by GPC (binder resin for toner, resin for forming coat layer of magnetic carrier)>
The molecular weight of the chromatogram by gel permeation chromatograph (GPC) is measured under the following conditions.

Resin adjusted to 0.05 to 0.6% by mass as a sample concentration by stabilizing the column in a heat chamber at 40 ° C., and flowing tetrahydrofuran (THF) as a solvent at a flow rate of 1 ml / min. Measurement is performed by injecting 50 to 200 μl of a THF sample solution. A refractive index (RI) detector is used as the detector. As a column, in order to accurately measure a molecular weight region of 10 ^{3 to} 2 × 10 ⁶ , it is preferable to combine a plurality of commercially available polystyrene gel columns, and a combination of μ-styragel 500, 103, 104, and 105 manufactured by Waters. In addition, a combination of shodex KA-801, 802, 803, 804, 805, 806, and 807 manufactured by Showa Denko is preferable.

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, for example, Pressure Chemical Co. Manufactured by Toyo Soda Kogyo Co., Ltd., with molecular weights of 6 × 10 ² , 2.1 × 10 ³ , 4 × 10 ³ , 1.75 × 10 ⁴ , 5.1 × 10 ⁴ , 1.1 × 10 ⁵ , It is preferable to use 3.9 × 10 ⁵ , 8.6 × 10 ⁵ , 2 × 10 ⁶ , 4.48 × 10 ⁶ , and use at least about 10 standard polystyrene samples.

  The resin for forming the coating layer is obtained by putting carrier particles in methyl ethyl ketone so as to have a concentration of 10% by mass, and performing a dispersion treatment for 2 minutes using an ultrasonic disperser “Tetora 150 type” (manufactured by Nikka Ki Bios). The filtrate obtained by filtering through a membrane filter having an opening of 0.2 μm is used.

<Measurement of maximum endothermic peak of release agent and toner>
The maximum endothermic peak of the release agent and toner can be measured according to ASTM D3418-82 using a differential thermal analyzer (DSC measuring device) and DSC2920 (TA Instruments Japan).
Temperature curve: Temperature increase I (30 ° C. to 200 ° C., temperature increase rate 10 ° C./min)
Temperature drop I (200 ° C-30 ° C, temperature drop rate 10 ° C / min)
Temperature increase II (30 ° C. to 200 ° C., temperature increase rate 10 ° C./min)

  As a measuring method, 5 to 20 mg, preferably 10 mg of a measurement sample is accurately weighed. This is put into an aluminum pan, and an empty aluminum pan is used as a reference, and measurement is performed at a temperature rise rate of 10 ° C./min and normal temperature and humidity in a measurement temperature range of 30 to 200 ° C. The maximum endothermic peak of the toner is the one having the highest height from the base line in the region above the endothermic peak of the glass transition temperature (Tg) of the resin in the process of temperature increase II, or the endothermic peak of Tg of the resin. When it is difficult to discriminate overlap with another endothermic peak, the maximum endothermic peak of the toner of the present invention is defined as the highest peak from the maximum peak of the overlapping peak.

<Measurement of particle size of magnetic carrier>
With respect to the particle size of the magnetic carrier particles, 300 or more magnetic carrier particles having a particle size of 1 μm or more are randomly extracted by a scanning electron microscope (2,000 times), and a digitizer uses a number average horizontal ferret diameter to obtain magnetic The average particle size in the particle size distribution based on the number of carriers is used.

<Measurement of particle size of magnetic substance and nonmagnetic inorganic compound in magnetic carrier>
The particle size of the magnetic substance and non-magnetic inorganic compound was obtained by randomly extracting 300 or more particles having a particle size of 5 nm or more with a scanning electron microscope (50,000 times) by cutting a magnetic carrier with a microtome. The minor axis is measured with a digitizer, and the average is taken as the particle size, and the particle size distribution of 300 or more particles (column widths 5-15, 15-25, 25-35, 35-45, 45-55, The particle size in the number distribution with the particle size of the center value of the column that becomes the peak (from the histogram of the column divided every 10 nm) such as 55-65, 65-75, 75-85, 85-95,. Calculate the maximum peak value in the distribution.

<Measurement of particle size of fine particles contained in magnetic carrier>
The particle size of the fine particles was determined by randomly scanning 500 particles having a particle size of 5 nm or more with a scanning electron microscope (50,000 times) from a component obtained by dissolving the coating material from a magnetic carrier in a solvent such as toluene. Extracted above, measured the major axis and minor axis with a digitizer, averaged to be the particle size, particle size distribution of 500 or more particles (column width 5-15, 15-25, 25-35, 35- 45, 45-55, 55-65, 65-75, 75-85, 85-95, etc. (from the histogram of the column divided every 10 nm) The maximum peak value in the particle size distribution in the number distribution is calculated.

<Measurement of particle size of inorganic fine particles of toner>
As for the particle size of the inorganic fine particles (external additive) on the surface of the toner, 500 or more particles having a particle size of 5 nm or more are randomly extracted by a scanning electron microscope (50,000 times), and the major axis and the minor axis are digitized. The particle size distribution of 500 or more particles (column widths 5-15, 15-25, 25-35, 35-45, 45-55, 55-65, 65 In the particle size distribution in the number distribution of inorganic fine particles, the particle size becomes the peak of the center value of the column (from the column histogram divided every 10 nm, such as −75, 75-85, 85-95,...). Calculate the maximum peak value.

<Measurement of magnetization intensity of magnetic carrier>
The strength of magnetization of the magnetic carrier is determined from the magnetic properties of the magnetic carrier and the true specific gravity of the magnetic carrier. The magnetic characteristics of the magnetic carrier can be measured by using an oscillating magnetic field type magnetic characteristic automatic recording apparatus BHV-30 manufactured by Riken Denshi Co., Ltd. As a measurement method, a cylindrical plastic container was filled with a magnetic carrier so as to be sufficiently dense, while an external magnetic field of 79.6 kA / m (1 kiloOersted) was created, and the container was filled in this state. Measure the magnetization moment of the magnetic carrier. Further, the actual mass of the magnetic carrier filled in the container is measured to determine the magnetization strength (Am ² / kg) of the magnetic carrier.

<Measurement of true specific gravity of magnetic carrier>
The true specific gravity of the magnetic carrier particles can be determined by a dry automatic densimeter autopycnometer.

<Measurement of specific resistance of magnetic carrier, nonmagnetic inorganic compound, magnetic substance and conductive fine particles>
The specific resistance values of the magnetic carrier, the nonmagnetic inorganic compound, the magnetic material, and the conductive fine particles are measured using the measuring apparatus shown in FIG. The cell E is filled with carrier particles, the lower electrode 11 and the upper electrode 12 are arranged so as to be in contact with the filled carrier particles, a voltage is applied between these electrodes, and the current flowing at that time is measured to compare the ratio. A method for obtaining resistance is used. The measurement conditions of the specific resistance in the present invention are a contact area S between the filled carrier particles and the electrode = about 2.3 cm ² , a thickness d = about 0.5 mm, and a load of the upper electrode 12 of 180 g. In FIG. 1, 13 is an insulator, 14 is an ammeter, 15 is a voltmeter, 16 is a constant voltage device, 17 is a magnetic carrier, and 18 is a guide ring.

<Measurement of contact angle of magnetic carrier>
As a method for measuring the contact angle of the magnetic carrier, a contact angle with water is measured using a WTMY-232A wet tester manufactured by Sankyo Piotech.

  13.2 g of the magnetic carrier is gently put into the measuring cell, and a tapping operation is performed for 1 minute at a tapping speed of 30 times / min using a Tapping Machine PTM-1 manufactured by Sankyo Piotech Co., Ltd. This is set in a measuring apparatus and measured.

  First, the specific surface area of the powder layer is obtained by the air permeation method, and then the pressure inflection point is obtained by the constant flow method. The contact angle of the magnetic carrier is calculated from both.

<Measurement of repose angle when toner concentration of developer is 8% by mass>
The developer is prepared by putting 4 g of toner and 46 g of magnetic carrier in a 50 ml plastic bottle so that the toner concentration becomes 8% by mass, and then 150 reciprocations / min with a Yayoi type shaker (model: YS-LD). Shake for 120 seconds. At this time, the angle of shaking is such that the shaking column moves 15 degrees forward and 20 degrees backward, assuming that the vertical (vertical) of the shaker is 0 degree. And it is shaken once forward and backward once, and when returning to just above, it counts as one reciprocation.

  For measuring the angle of repose of the developer, a powder tester P-100 (manufactured by Hosokawa Micron Corporation) is used, and the developer is deposited on a circular table having a diameter of 8 cm through a mesh having an opening of 502 μm. At this time, the developer is deposited so as to overflow from the end of the table. At this time, the angle formed between the ridge line of the developer deposited on the table and the circular table surface is measured with a laser beam to be the repose angle of the developer in the present invention.

  Specific examples of the present invention will be described below, but the present invention is not limited to these examples.

(Example of manufacturing carrier core A)
4.0 mass% and 2.0 mass% silane cups for magnetite fine particles with an average particle size of 250 nm in the particle size distribution on the number basis and hematite fine particles with an average particle size of 600 nm on the particle size distribution on the number basis, respectively. A ring agent (3- (2-aminoethylaminopropyl) trimethoxysilane) was added, and the mixture was stirred and mixed at a high speed at 100 ° C. or higher in a container to make each fine particle lipophilic.
-Phenol 10 parts by mass-Formaldehyde solution (formaldehyde 37% by weight aqueous solution) 6 parts by mass-59 parts by weight of the above treated magnetite fine particles-25 parts by weight of the above treated hematite fine particles 25 parts by weight of the above materials, 28 parts by weight of ammonia water, water 10 parts by mass was placed in a flask, heated and maintained at 85 ° C. over 30 minutes while stirring and mixing, and cured by polymerization reaction for 3 hours. Then, after cooling to 30 degreeC and adding water, the supernatant liquid was removed, the precipitate was washed with water, and then air-dried. Next, this was dried under reduced pressure (5 mmHg or less) at a temperature of 60 ° C., and a spherical magnetic material-dispersed resin core (carrier core) having an average particle size of 33 μm in the particle size distribution on the basis of the number of magnetic materials dispersed. A) was obtained.

(Example of manufacturing carrier core B)
3.0% by mass of a silane coupling agent (3- (3) for the magnetite fine particles having an average particle size of 300 nm in the particle size distribution on the number basis and the hematite fine particles having an average particle size of 300 nm on the particle size distribution on the number basis. 2-aminoethylaminopropyl) trimethoxysilane) was added, and the mixture was stirred at a high speed at 100 ° C. or higher in the container to treat each fine particle.
-Phenol 10 parts by mass-Formaldehyde solution (formaldehyde 37 mass% aqueous solution) 6 parts by mass-Treated magnetite fine particles 76 parts by mass-Treated hematite fine particles 8 parts by mass The above materials, 28 mass% ammonia water 5 parts by mass, water 10 parts by mass was placed in a flask, heated and maintained at 85 ° C. over 30 minutes while stirring and mixing, and cured by polymerization reaction for 3 hours. Then, after cooling to 30 degreeC and adding water, the supernatant liquid was removed, the precipitate was washed with water, and then air-dried. Next, this is dried under reduced pressure (5 mmHg or less) at a temperature of 60 ° C., and a spherical magnetic material-dispersed resin core (carrier core) having an average particle size of 32 μm in the particle size distribution based on the number of magnetic materials dispersed. B) was obtained.

(Production example of carrier core C)
2.0% by mass of a titanium coupling agent isopropyltri (N-aminoethyl-aminoethyl) titanate is added to magnetite fine particles having an average particle size of 0.25 μm in the particle size distribution on the basis of the number, and 100 in a container. The fine particles were processed by mixing and stirring at a high speed at a temperature of not lower than ° C.
-Phenol 10 parts by mass-Formaldehyde solution (formaldehyde 37% by weight aqueous solution) 6 parts by mass-The above treated magnetite fine particles 84 parts by weight The above materials, 28 parts by weight ammonia water 6 parts by weight and water 10 parts by weight are placed in a flask and stirred. The mixture was heated and maintained at 85 ° C. for 30 minutes with mixing, and was cured by polymerization for 3 hours. Then, after cooling to 30 degreeC and adding water, the supernatant liquid was removed, the precipitate was washed with water, and then air-dried. Next, this is dried under reduced pressure (5 mmHg or less) at a temperature of 60 ° C., and a spherical magnetic material-dispersed resin core (carrier core) having an average particle size of 35 μm in the particle size distribution on the basis of the number of magnetic materials dispersed. C) was obtained.

(Example of manufacturing carrier core D)
The mixture was weighed so that the molar ratio was Fe ₂ O ₃ = 52 mol%, CuO = 16 mol%, and MgO = 32 mol%, and mixed for 10 hours using a ball mill. This was calcined at 900 ° C. for 2 hours, pulverized with a ball mill, and further granulated with a spray dryer. This was sintered at 1150 ° C. for 10 hours, pulverized, and further classified to obtain a spherical magnetic carrier core (carrier core D) having an average particle size of 34 μm in the particle size distribution on the number basis.

(Manufacture example 1 of coating resin)
Following formula

100 parts by mass of the monomer having the structure represented by the following formula is added to a four-necked flask equipped with a reflux condenser, a thermometer, a nitrogen suction tube and a mixing type stirring apparatus, and further 100 parts by mass of toluene, 100 parts by mass of methyl ethyl ketone, azo Add 2.0 parts by weight of bisisovaleronitrile and keep at 70 ° C. for 10 hours under a nitrogen stream.

The polymer (E) solution (solid content 33 mass%) which has a unit shown by was obtained. The weight average molecular weight by the gel permeation chromatogram (GPC) of the polymer (E) was 40,000.

(Manufacture example 2 of coating resin)
Following formula

2 parts by mass of a methyl methacrylate macromer having a weight average molecular weight of 5,000 having an ethylenically unsaturated group at one end represented by the following formula:

In addition, 55 parts by mass of a monomer having a structure represented by the following formula and 43 parts by mass of methyl methacrylate are added to a four-necked flask equipped with a reflux condenser, a thermometer, a nitrogen suction pipe and a mixing type stirring device, and further 90 parts by mass of toluene, Add 110 parts by weight of methyl ethyl ketone and 2.0 parts by weight of azobisisovaleronitrile, and maintain at 70 ° C. for 10 hours under a nitrogen stream.

[Wherein, a1, b1, c1 and d1 each independently represents an integer of 1 or more. ]
The graft copolymer (F) solution (solid content 33 mass%) which has a unit shown by this was obtained. The weight average molecular weight by the gel permeation chromatogram (GPC) of the graft copolymer (F) was 35,000.

(Manufacture example 3 of coating resin)
Following formula

5 parts by weight of a methyl methacrylate macromer having a weight average molecular weight of 9,000 having an ethylenically unsaturated group at one end represented by the following formula:

50 parts by mass of a monomer having a structure represented by the formula: 45 parts by mass of methyl methacrylate are added to a four-necked flask equipped with a reflux condenser, a thermometer, a nitrogen suction tube, and a mixing type stirring device, and further 90 parts by mass of toluene, Add 110 parts by weight of methyl ethyl ketone and 0.7 parts by weight of azobisisovaleronitrile, and keep at 70 ° C. for 10 hours under a nitrogen stream.

[Wherein, a2, b2, c2 and d2 each independently represents an integer of 1 or more. ]
The graft copolymer (G) solution (solid content 33 mass%) which has a unit shown by this was obtained. The weight average molecular weight by the gel permeation chromatogram (GPC) of the graft copolymer (G) was 150,000.

(Manufacture example 4 of coating resin)
Following formula

2 parts by mass of a methyl methacrylate macromer having a weight average molecular weight of 5,000 having an ethylenically unsaturated group at one end represented by the formula:

20 parts by mass of a monomer having a structure represented by the following formula and 78 parts by mass of methyl methacrylate were added to a four-necked flask equipped with a reflux condenser, a thermometer, a nitrogen suction tube and a mixing type stirring device, and further 90 parts by mass of toluene, Add 110 parts by weight of methyl ethyl ketone and 2.0 parts by weight of azobisisovaleronitrile, and maintain at 70 ° C. for 10 hours under a nitrogen stream.

[Wherein, a3, b3, c3 and d3 each independently represents an integer of 1 or more. ]
The graft copolymer (H) solution (solid content 33 mass%) which has a unit shown by this was obtained. The weight average molecular weight by the gel permeation chromatogram (GPC) of the graft copolymer (H) was 39,000.

(Toner Production Example 1)
2.0 mol of styrene, 0.21 mol of 2-ethylhexyl acrylate, 0.14 mol of fumaric acid, 0.03 mol of dimer of α-methylstyrene, and 0.05 mol of dicumyl peroxide are placed in a dropping funnel. In addition, 7.0 mol of polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene (2.2) -2,2-bis (4-hydroxyphenyl) propane; 0 mol, 3.2 mol of terephthalic acid, 1.8 mol of trimellitic anhydride, 4.9 mol of fumaric acid, and 0.2 g of dibutyltin oxide are placed in a 4-liter glass four-necked flask. A thermometer, a stirring rod, a condenser, and a nitrogen introducing tube were attached to the four-necked flask, and the four-necked flask was placed in a mantle heater. Next, after the inside of the four-necked flask was replaced with nitrogen gas, the temperature was gradually increased while stirring, and while stirring at a temperature of 145 ° C., the monomer of the vinyl polymer unit was crosslinked from the previous dropping funnel. An agent and a polymerization initiator were added dropwise over 4 hours. Next, the temperature was raised to 200 ° C. and reacted for 4 hours to obtain a resin X having a weight average molecular weight of 80000 and a number average molecular weight of 3200.
-Resin X 100 parts by mass-Fischer-Tropsch wax (maximum endothermic peak temperature 80 ° C) 5 parts by mass-3,5-di-t-butylsalicylic acid aluminum compound 0.5 parts by mass I. Pigment Blue 15: 3 5 parts by mass After mixing the material of the above formulation with a Henschel mixer (FM-75 type, manufactured by Mitsui Miike Chemical Co., Ltd.), a twin-screw kneader (PCM-30 type) set at a temperature of 130 ° C. And kneaded by Ikegai Iron Works Co., Ltd.). The obtained kneaded material was cooled and coarsely pulverized to 1 mm or less with a hammer mill to obtain a coarsely pulverized material. The obtained coarsely pulverized toner was pulverized using a collision-type airflow pulverizer using high-pressure gas. Further, the particles were classified by a multi-division classifier using the Coanda effect to obtain cyan particles. Furthermore, surface modification was performed by a hybridizer (manufactured by Nara Machinery Co., Ltd.) to obtain cyan particles having a weight average particle size of 6.5 μm, an average particle size of 5.3 μm in a particle size distribution on a number basis, and an average circularity of 0.935. Obtained.

  In 100 parts by mass of the obtained cyan particles, 1.5 parts by mass of silica particles having a maximum peak value at 130 nm in the particle size distribution on the basis of number, and titanium oxide particles having a maximum peak value at 40 nm in the particle size distribution on the basis of number 0.7 parts by mass was added and mixed with a Henschel mixer (FM-75 type, manufactured by Mitsui Miike Chemical Co., Ltd.) to obtain toner 1. As a result of measuring the degree of aggregation of the toner, it was 43. Further, the transmittance (%) of the toner 1 in a 45 volume% methanol aqueous solution was 44%.

(Toner Production Example 2)
3.6 mol of polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, 1.6 mol of polyoxyethylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, 1.7 mol of terephthalic acid, 1.2 mol of trimellitic anhydride, 2.4 mol of fumaric acid and 0.12 g of dibutyltin oxide are put into a 4-liter four-necked flask made of glass, and a thermometer and a stirring bar are placed in the four-necked flask. A condenser and a nitrogen inlet tube were attached, and the four-necked flask was placed in a mantle heater. Under a nitrogen atmosphere, reaction was performed at 215 ° C. for 5 hours to obtain a resin Y having a weight average molecular weight of 30,000 and a number average molecular weight of 3800.
-Resin Y 100 parts by mass-3,5-di-t-butylsalicylic acid aluminum compound 0.5 parts by mass-C.I. I. Pigment Blue 15: 3 5 parts by mass Cyanide particles were obtained in the same manner as in Toner Production Example 1 using the material having the above formulation. Furthermore, surface modification was performed by a hybridizer (manufactured by Nara Machinery Co., Ltd.), and cyan particles having a weight average particle size of 6.6 μm, a particle size distribution with an average particle size of 5.2 μm, and an average circularity of 0.931 were obtained. Obtained.

  To 100 parts by mass of the obtained cyan particles, 1.5 parts by mass of silica particles having a maximum peak value at 90 nm in the particle size distribution on the number basis, and titanium oxide particles having a maximum peak value at 50 nm on the particle size distribution on the number basis Was added with 0.8 parts by mass and mixed with a Henschel mixer (FM-75 type, manufactured by Mitsui Miike Chemical Co., Ltd.) to obtain toner 2. As a result of measuring the degree of aggregation of the toner, it was 31. Further, the transmittance (%) of the toner 2 in a 45 volume% methanol aqueous solution was 64%.

(Toner Production Example 3)
-85 parts by weight of styrene-15 parts by weight of n-butyl acrylate-3 parts by weight of acrylic acid-6 parts by weight of dodecanethiol-1 part by weight of carbon tetrabromide 1.5 parts by mass of an activator (Sanyo Kasei Co., Ltd .: Nonipol 400) and 2.5 parts by mass of an anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd .: Neogen SC) are added to 140 parts by mass of ion-exchanged water. Dispersed in a flask, emulsified, and slowly mixed for 10 minutes, charged with 10 parts by mass of ion-exchanged water having 1 part by mass of ammonium persulfate dissolved therein, and after nitrogen substitution, While stirring in the flask, the contents were heated in an oil bath until the content reached 70 ° C., and emulsion polymerization was continued for 5 hours. A resin particle dispersion 1 having an average particle size of 0.15 μm in the particle size distribution on a number basis was prepared.

Also,
-Styrene 75 parts by mass-n-butyl acrylate 25 parts by mass-Acrylic acid 2 parts by mass Mixing and dissolving the materials of the above formulation, a nonionic surfactant (Sanyo Kasei Co., Ltd .: Nonipol 400) 1 .5 parts by mass and 3 parts by mass of an anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd .: Neogen SC) dissolved in 150 parts by mass of ion-exchanged water were dispersed in a flask, emulsified, and 10 minutes. While slowly mixing, 10 parts by mass of ion-exchanged water in which 0.8 parts by mass of ammonium persulfate was dissolved was added, and after nitrogen replacement, the contents were kept at 70 ° C. while stirring the flask. Emulsion polymerization was continued as it was for 5 hours by heating in an oil bath, and a resin particle dispersion 2 having an average particle size of 0.11 μm in the particle size distribution on the basis of the number was prepared.

further,
Paraffin wax (melting point 95 ° C.) 50 parts by mass Anionic surfactant 5 parts by mass (Daiichi Kogyo Seiyaku Co., Ltd .: Neogen SC)
・ Ion-exchanged water 200 parts by mass The material having the above formulation is heated to 97 ° C. and dispersed using a homogenizer (manufactured by IKA: Ultra Turrax T50), and then dispersed with a pressure discharge homogenizer. A release agent particle dispersion was prepared by dispersing a release agent having an average particle size of 0.4 μm in the particle size distribution.

further,
・ C. I. Pigment Blue 15: 3 12 parts by mass / Anionic surfactant 2 parts by mass (Daiichi Kogyo Seiyaku Co., Ltd .: Neogen SC)
-Ion-exchange water 78 mass parts The material of said prescription was mixed and it disperse | distributed using the sand grinder mill.

further,
-150 parts by mass of the resin particle dispersion 1-210 parts by mass of the resin particle dispersion 2-40 parts by mass of the colorant dispersion-70 parts by mass of the release agent dispersion 70 Was put into a 1 liter separable flask equipped with, and stirred. The mixture was adjusted to pH = 5.2 using 1N potassium hydroxide.

  150 parts by mass of a 10% aqueous sodium chloride solution as a flocculant was added dropwise to this mixed solution, and the mixture was heated to 70 ° C. while stirring the inside of the flask in a heating oil bath. At this temperature, 3 parts by mass of the resin particle dispersion 2 was added. After holding at 60 ° C. for 1 hour, 3 parts by mass of an anionic surfactant (Daiichi Kogyo Seiyaku Co., Ltd .: Neogen SC) was added thereto, and then the stainless steel flask was sealed and stirred using a magnetic seal. The mixture was heated to 90 ° C. while maintaining for 3 hours. Then, after cooling, the reaction product is filtered, washed thoroughly with ion-exchanged water, and then dried, so that the weight average particle size is 6.0 μm, the average particle size is 5.1 μm in the particle size distribution on the number basis, the average Cyan particles having a circularity of 0.970 were obtained.

To 100 parts by mass of the obtained cyan particles, 1.8 parts by mass of silica particles having a maximum peak value at 130 nm in the particle size distribution on the number basis, and titanium oxide particles having a maximum peak value at 50 nm on the particle size distribution on the number basis Was added with 0.8 parts by mass and mixed with a Henschel mixer (FM-75 type, manufactured by Mitsui Miike Chemical Co., Ltd.) to obtain toner 3. The degree of aggregation of the toner was measured and found to be 64. Further, the transmittance (%) of the toner 3 in a 45 volume% methanol aqueous solution was 55%.

< Reference Example 1>
For 30 parts by mass of the graft copolymer (E) solution, 0.5 parts by mass of titanium oxide particles having a maximum peak value at 140 nm and a homogenizer of 100 parts by mass of toluene in the particle size distribution on the basis of the number obtained by the sol-gel method. Mix better. Subsequently, the above coating liquid was gradually added while stirring 2000 parts by mass of carrier core A while continuously applying shear stress, and the solvent was volatilized at 70 ° C. to perform resin coating on the carrier surface. The resin-coated magnetic carrier particles were heat-treated with stirring at 100 ° C. for 2 hours, cooled, crushed, classified by a sieve having an aperture of 76 μm, and an average particle size of 33 μm in the particle size distribution on the basis of number A magnetic carrier having a specific gravity of 3.59 g / cm ³ , a magnetization strength of 39 Am ² / kg, a specific resistance of 8 × 10 ¹² Ω · cm, and a contact angle of 101 ° was obtained. Also, 10 g of magnetic carrier (exact balance) is placed in 30 g of methyl ethyl ketone in a polycup, and dispersed for 5 minutes using an ultrasonic disperser “Tetora 150 type” (manufactured by Nikka Ki Bios). , Trap the carrier, transfer the upper stack liquid to another poly cup, dry the remaining carrier core with a vacuum dryer, and calculate the coating amount (total amount) by the difference between the charged carrier and the dried core . The supernatant liquid is filtered through a membrane filter having an opening of 0.20 μm, the filtrate is dried, and the resin content is calculated. The particle diameter was measured using the particles on the membrane filter. The results are summarized in Table 1. The same applies to the following examples.

  To 90 parts by mass of this carrier, 10 parts by mass of toner 1 was added and mixed with a tumbler mixer to obtain a developer. As a result of measuring the triboelectric charge amount, it was −29.4 mC / kg, and the angle of repose when the toner concentration was 8 mass% was 38 °.

Using this developer, Canon CLC5000 modified full-color copier (with a reduced laser spot diameter and 600 dpi output, changing the surface of the fixing roller of the fixing unit to a PFA tube, and removing the oil coating mechanism) The image was evaluated under normal temperature and normal humidity (23 ° C., 60% RH). The developing condition is that the developing sleeve and the photosensitive member are rotated in the forward direction in the developing region, the developing sleeve is 1.85 times the photosensitive member, Vd-600 V, Vl-110 V, Vdc-450 V, Vpp 2 kV, frequency 1 8 kHz. The items for image evaluation and the evaluation criteria are shown below.
(1) Dot reproducibility A 30H image was formed using the toner and the remodeling machine, this image was visually observed, and the dot reproducibility of the image was evaluated based on the following criteria. Note that the 30H image is a halftone image when 256 gradations are displayed in hexadecimal, 00H is solid white, and FFH is solid black.
A: Smooth and smooth.
B: I don't feel a lot of rustling.
C: Although there is a slight feeling of roughness, it is at a level where there is no practical problem.
D: There is a feeling of roughness and is a problem.
E: There is a very rough feeling.
(2) Image density The image density of a fixed image when the solid image was fixed at 180 ° C. was measured.
(3) Image Defect Evaluation A chart in which halftone horizontal bands (30H width 10 mm) and solid black horizontal bands (FFH width 10 mm) are alternately arranged in the transfer paper conveyance direction is output. The image is read by a scanner and binarized. Taking the luminance distribution (256 gradations) of a certain line in the conveyance direction of the binarized image, drawing a tangent to the luminance of the halftone at that time, and deviating from the tangent at the rear end of the halftone part until it intersects with the solid part luminance The brightness area (area: sum of the brightness numbers) is used as the whiteness degree.
A: 50 or less Almost inconspicuous and very good.
B: 51 to 150 Good.
C: 151 to 300 There are white spots, but it is at a level where there is no practical problem.
D: 301 to 600 White spots are conspicuous, which is a problem.
E: 601 or more Very noticeable.

  In this example, the dot reproducibility in the 30H image was very good. Also, the image density was high and white spots were observed, but the level was not problematic for practical use.

  Also, a 10,000 sheet endurance test using a 3% chart was conducted, and after the end of the endurance test, the triboelectric charge amount, dot reproducibility, image density, and white spot of the toner were evaluated by the same method as described above. did. As a result, no change in charge amount due to carrier spent or the like was observed, white spots were not changed, and there was no problem in practical use. Moreover, a high-quality image without fogging was obtained. Table 1 shows the physical properties of the carrier particles, and Table 2 shows the test results of the developer.

< Reference Example 2>
With respect to 60 parts by mass of the graft copolymer (E) solution, 1 part by mass of silica particles having a maximum peak value at 320 nm in the number-based particle size distribution obtained by the sol-gel method, and 35 nm in the number-based particle size distribution. 1 part by mass of carbon black having the maximum peak value and 200 parts by mass of toluene are mixed well by a homogenizer. Subsequently, the above coating liquid was gradually added while stirring 2000 parts by mass of carrier core A while continuously applying shear stress, and the solvent was volatilized at 70 ° C. to perform resin coating on the carrier surface. The resin-coated magnetic carrier particles were heat-treated with stirring at 100 ° C. for 2 hours, cooled, crushed, classified by a sieve having an aperture of 76 μm, and an average particle size of 33 μm in the particle size distribution on the basis of number A magnetic carrier having a specific gravity of 3.57 g / cm ³ , a magnetization strength of 39 Am ² / kg, a specific resistance of 7 × 10 ¹² Ω · cm, and a contact angle of 102 ° was obtained.

10 parts by mass of toner 1 was added to 90 parts by mass of the carrier, and a developer was prepared in the same manner as in Reference Example 1. As a result of measuring the triboelectric charge amount, it was −32.1 mC / kg, and the angle of repose when the toner concentration was 8% by mass was 37 °.

A test was conducted in the same manner as in Example 1 using this developer. As a result, white spots were improved with respect to Reference Example 1. Table 1 shows the physical properties of the carrier particles, and Table 2 shows the test results of the developer.

<Example 1 >
With respect to 60 parts by mass of the graft copolymer (F) solution, 3 parts by mass of silica particles having a maximum peak value at 290 nm in the particle size distribution on the basis of the number obtained by the sol-gel method, and 35 nm in the particle size distribution on the basis of the number 2 parts by mass of carbon black having the maximum peak value and 200 parts by mass of toluene are mixed well by a homogenizer. Next, the above coating solution was gradually added while stirring 2000 parts by mass of carrier core A while continuously applying shear stress, and the solvent was volatilized at 70 ° C. to perform resin coating on the surface of the carrier. The resin-coated magnetic carrier particles were heat-treated with stirring at 100 ° C. for 2 hours, cooled, crushed, classified by a sieve having an aperture of 76 μm, and an average particle size of 33 μm in the particle size distribution on the basis of number A magnetic carrier having a specific gravity of 3.55 g / cm ³ , a magnetization strength of 38 Am ² / kg, a specific resistance of 4 × 10 ¹² Ω · cm, and a contact angle of 120 ° was obtained.

10 parts by mass of toner 1 was added to 90 parts by mass of the carrier, and a developer was prepared in the same manner as in Reference Example 1. As a result of measuring the triboelectric charge amount, it was -31.5 mC / kg, and the angle of repose when the toner concentration was 8% by mass was 32 °.

A test was conducted in the same manner as in Reference Example 1 using this developer. As a result, no white spots were observed, the image density was high, and good developability was obtained. Further, almost no deterioration of the toner and carrier in durability was observed, and good results were obtained. Table 1 shows the physical properties of the carrier particles, and Table 2 shows the test results of the developer.

<Example 2 >
7 parts by mass of titanium oxide particles having a maximum peak value at 140 nm in the particle size distribution based on the number obtained by the sol-gel method and 14 nm in the particle size distribution based on the number based on 210 parts by mass of the graft copolymer (F) solution. 7 parts by mass of carbon black having the maximum peak value and 500 parts by mass of toluene are mixed well by a homogenizer. Next, 2000 parts by mass of carrier core A A was put in a fluidized bed coating apparatus, and the above coating solution was sprayed to carry out resin coating on the carrier surface at 70 ° C. The resin-coated magnetic carrier particles were heat-treated while forming a fluidized bed at 100 ° C. for 2 hours, and were taken out after cooling while maintaining the fluidized bed. After pulverization, the particles are classified with a sieve having an aperture of 76 μm, and the average particle size is 35 μm, the true specific gravity is 3.54 g / cm ³ , the magnetization strength is 38 Am ² / kg, and the specific resistance is 5 × 10 ^14. A magnetic carrier with Ω · cm and a contact angle of 110 ° was obtained.

10 parts by mass of toner 1 was added to 90 parts by mass of the carrier, and a developer was prepared in the same manner as in Reference Example 1. As a result of measuring the triboelectric charge amount, it was -43.0 mC / kg, and the angle of repose when the toner concentration was 8% by mass was 35 °.

A test was conducted in the same manner as in Reference Example 1 using this developer. As a result, white spots, particularly roughness, were good. Moreover, the characteristics after durability were also good. Table 1 shows the physical properties of the carrier particles, and Table 2 shows the test results of the developer.

<Example 3 >
With respect to 60 parts by mass of the graft copolymer (G) solution, 2 parts by mass of titanium oxide particles having a maximum peak value at 140 nm in the particle size distribution based on the number obtained by the sol-gel method, and 103 nm in the particle size distribution based on the number. 6 parts by mass of tin oxide having a maximum peak value (Pastran 4310, manufactured by Mitsui Kinzoku Co., Ltd.) and 200 parts by mass of toluene are mixed well by a homogenizer. Next, the above coating solution is gradually added while stirring 2000 parts by mass of carrier core A while continuously applying shear stress, coating is performed in the same manner as in Reference Example 1, and the average particle size in the particle size distribution on a number basis is applied. A magnetic carrier having a thickness of 33 μm, a true specific gravity of 3.59 g / cm ³ , a magnetization strength of 38 Am ² / kg, a specific resistance of 9 × 10 ¹² Ω · cm, and a contact angle of 105 ° was obtained.

10 parts by mass of toner 1 was added to 90 parts by mass of the carrier, and a developer was prepared in the same manner as in Reference Example 1. As a result of measuring the triboelectric charge amount, it was -30.3 mC / kg, and the angle of repose when the toner concentration was 8% by mass was 37 °.

A test was conducted in the same manner as in Reference Example 1 using this developer. As a result, the roughness and whiteness were good. As a result of the durability test, white spots were slightly deteriorated, but there was no practical problem. As a result of observing the carrier, a part where the coating material was not uniformly coated was observed. Table 1 shows the physical properties of the carrier particles, and Table 2 shows the test results of the developer.

<Example 4 >
In 90 parts by mass of the graft copolymer (F) solution, 4.5 parts by mass of silica particles having a maximum peak value at 290 nm in the particle size distribution on the basis of the number obtained by the sol-gel method, in the particle size distribution on the basis of the number 3 parts by mass of carbon black having a maximum peak value at 29 nm and 200 parts by mass of toluene are mixed well by a homogenizer. Next, the carrier core A is changed to 2000 parts by mass of the carrier core B, and the above coating liquid is gradually added while stirring while continuously applying shear stress, and the solvent is volatilized at 70 ° C. to coat the resin surface on the carrier surface. went. The resin-coated magnetic carrier particles were heat-treated with stirring at 100 ° C. for 2 hours, cooled, crushed, classified with a sieve having a mesh size of 76 μm, and an average particle size of 32 μm in the particle size distribution on the basis of number. A magnetic carrier having a specific gravity of 3.60 g / cm ³ , a magnetization strength of 49 Am ² / kg, a specific resistance of 4 × 10 ¹¹ Ω · cm, and a contact angle of 115 ° was obtained.

10 parts by mass of toner 1 was added to 90 parts by mass of the carrier, and a developer was prepared in the same manner as in Reference Example 1. As a result of measuring the triboelectric charge amount, it was -34.4 mC / kg, and the angle of repose when the toner concentration was 8% by mass was 34 °.

A test was conducted in the same manner as in Reference Example 1 using this developer. As a result, no white spots were observed, the image density was high, and good developability was obtained. There was a slight change in the image quality after durability, but it was at a level that had no practical problems such as white spots and roughness. Table 1 shows the physical properties of the carrier particles, and Table 2 shows the test results of the developer.

<Example 5 >
In 90 parts by mass of the graft copolymer (F) solution, 3 parts by mass of the crosslinked polymethyl methacrylate particles having a maximum peak value at 220 nm in the particle size distribution on the basis of the number obtained by soap-free emulsion polymerization, 3 parts by mass of carbon black having a maximum peak value at 29 nm in the particle size distribution and 200 parts by mass of toluene are mixed well by a homogenizer. Next, the carrier core A is changed to 2000 parts by mass of the carrier core C2000, and the coating liquid is gradually added while stirring while continuously applying shear stress, and the resin coating is performed on the carrier surface in the same manner as in Reference Example 1. It was. A magnetic carrier having an average particle size of 35 μm, a true specific gravity of 3.62 g / cm ³ , a magnetization intensity of 61 Am ² / kg, a specific resistance of 7 × 10 ¹⁰ Ω · cm, and a contact angle of 107 ° in a particle size distribution on the number basis was obtained. .

10 parts by mass of toner 1 was added to 90 parts by mass of the carrier, and a developer was prepared in the same manner as in Reference Example 1. As a result of measuring the triboelectric charge amount, it was -36.0 mC / kg, and the angle of repose when the toner concentration was 8% by mass was 36 °.

A test was conducted in the same manner as in Reference Example 1 using this developer. As a result, white spots were good and slight changes were observed in the roughness and white spots after endurance. Table 1 shows the physical properties of the carrier particles, and Table 2 shows the test results of the developer.

< Reference Example 3 >
Manufactured in the same manner as Toner 1 except that silica particles in toner 1 are not added and titanium oxide particles are changed to 1.0 part by mass with respect to 90 parts by mass of the carrier used in Reference Example 2 and mixed with a Henschel mixer. 10 parts by mass of the toner (coagulation degree 35, transmittance (%) in an aqueous solution of 45% by volume of methanol is 53%) was added, and a developer was prepared in the same manner as in Reference Example 1. As a result of measuring the triboelectric charge amount, it was −28.8 mC / kg, and the angle of repose when the toner concentration was 8 mass% was 38 °.

A test was conducted in the same manner as in Reference Example 1 using this developer. Table 1 shows the physical properties of the carrier particles, and Table 2 shows the test results of the developer.

< Reference Example 4 >
10 parts by weight of toner 2 was added to 90 parts by weight of the carrier used in Reference Example 2, and a developer was obtained in the same manner as in Example 1. As a result of measuring the triboelectric charge amount, it was -27.0 mC / kg, and the angle of repose when the toner concentration was 8% by mass was 35 °.

Using this developer, image evaluation was performed under normal temperature and humidity (23 ° C., 60% RH) using a Canon full color copier CLC5000. The development conditions were a contrast potential of 340V and a fog removal potential of 150V. The same test as in Reference Example 1 was performed. As a result, a good image was obtained. Table 1 shows the physical properties of the carrier particles, and Table 2 shows the test results of the developer.

< Reference Example 5 >
9 parts by weight of toner 3 was added to 91 parts by weight of the carrier used in Reference Example 2, and a developer was prepared in the same manner as in Reference Example 1. As a result of measuring the triboelectric charge amount, it was -31.3 mC / kg, and the angle of repose when the toner concentration was 8% by mass was 36 °.

A test was conducted in the same manner as in Reference Example 1 using this developer. As a result, a good image excellent in transferability was obtained. Table 1 shows the physical properties of the carrier particles, and Table 2 shows the test results of the developer.

  Table 1 shows the physical properties of the carrier particles.

<Comparative Example 1>
With respect to 30 parts by mass of the graft copolymer (E) solution, 0.5 parts by mass of silica particles having a maximum peak value at 320 nm in the particle size distribution on the basis of the number obtained by the sol-gel method and 100 parts by mass of toluene by a homogenizer Mix well. Next, the carrier core A is changed to 2000 parts by mass of the carrier core D, and the above coating solution is gradually added while stirring while continuously applying a shear stress, and the solvent is volatilized at 70 ° C. to coat the resin surface on the carrier surface. went. The resin-coated magnetic carrier particles were heat-treated with stirring at 100 ° C. for 2 hours, cooled, crushed, classified with a sieve having an aperture of 76 μm, and an average particle size of 35 μm in the particle size distribution on the basis of number A magnetic carrier having a specific gravity of 5.04 g / cm ³ , a magnetization strength of 60 Am ² / kg, a specific resistance of 5 × 10 ⁸ Ω · cm, and a contact angle of 103 ° was obtained.

7 parts by mass of toner 1 was added to 93 parts by mass of this carrier, and a developer was prepared in the same manner as in Reference Example 1. As a result of measuring the triboelectric charge amount, it was -28.4 mC / kg, and the angle of repose when the toner concentration was 8% by mass was 37 °.

A test was conducted in the same manner as in Reference Example 1 using this developer. As a result, the white spots were good, but the roughness was poor, and after the endurance, the carrier was spent, the white spots were slightly deteriorated, and the roughness was also deteriorated. Table 1 shows the physical properties of the carrier particles, and Table 2 shows the test results of the developer.

<Comparative example 2>
100 parts by mass of a silicone resin (SR 2411 manufactured by Toray Dow Silicone Co., Ltd., 10% by mass), 3 parts by mass of γ-aminopropyltrimethoxysilane, and 200 parts by mass of toluene are mixed, and 1000 parts by mass of carrier core A is continuously subjected to shear stress. While stirring while adding, the coating solution was gradually added, and the solvent was volatilized at 70 ° C. to perform resin coating on the carrier surface. The resin-coated magnetic carrier particles were heat-treated with stirring at 200 ° C. for 1 hour, cooled, crushed, classified by a sieve having an aperture of 76 μm, and an average particle size of 34 μm in the particle size distribution on the basis of number A magnetic carrier having a specific gravity of 3.55 g / cm ³ , a magnetization strength of 38 Am ² / kg, a specific resistance of 5 × 10 ¹³ Ω · cm, and a contact angle of 100 ° was obtained.

To 90 parts by mass of this magnetic carrier, 10 parts by mass of toner 1 was added, and a developer was obtained in the same manner as in Reference Example 1. As a result of measuring the triboelectric charge amount, it was -30.2 mC / kg, and the angle of repose when the toner concentration was 8% by mass was 38 °.

A test was conducted in the same manner as in Reference Example 1 using this developer. As a result, the roughness was good, but the white spots were bad. Table 1 shows the physical properties of the magnetic carrier, and Table 2 shows the test results of the developer.

<Comparative Example 3>
The resin-coated was performed except for changing the graft copolymer of Example 1 (F) in the graft copolymer (H) in the same manner as in Example 1. A magnetic carrier having an average particle size of 33 μm, a true specific gravity of 3.54 g / cm ³ , a magnetization strength of 38 Am ² / kg, a specific resistance of 6 × 10 ¹² Ω · cm, and a contact angle of 94 ° in a particle size distribution on the number basis was obtained. .

10 parts by mass of toner 1 was added to 90 parts by mass of the carrier, and a developer was prepared in the same manner as in Reference Example 1. As a result of measuring the triboelectric charge amount, it was -34.4 mC / kg, and the angle of repose when the toner concentration was 8% by mass was 42 °.

A test was conducted in the same manner as in Reference Example 1 using this developer. As a result, the dot reproducibility was excellent, but the white spots were poor, the image density was low, and the developability was poor. Further, the carrier was deteriorated in durability, and white spots were further deteriorated. Table 1 shows the physical properties of the carrier particles, and Table 2 shows the test results of the developer.

It is a schematic sectional drawing of the apparatus which measures the specific resistance of the magnetic carrier of this invention, a magnetic body, and a nonmagnetic inorganic compound. It is the schematic which shows the state of the blank in this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Lower electrode 12 Upper electrode 13 Insulator 14 Ammeter 15 Voltmeter 16 Constant voltage device 17 Carrier 18 Guide ring d Sample thickness E Resistance measurement cell 21 Transfer material 22 Cross section of toner layer A White part B Sweep part

Claims (1)

In a two-component developer containing a toner and a magnetic carrier,
The angle of repose when the toner concentration of the two-component developer is 8% by mass is 30 to 41 °,
The toner comprises toner particles containing a binder resin, a release agent, and a colorant, and silica particles and titanium oxide particles as external additives, and the toner has an aggregation degree of 20 to 90, The magnetic carrier is formed by coating the surface of a magnetic material-dispersed resin core containing at least a magnetic material and a binder resin with a coating material,
The coating material has the following formula

A methyl methacrylate macromer having a weight average molecular weight of 5,000 to 9,000 represented by :
A methacrylic acid ester having a perfluoroalkyl unit for forming a unit represented by the following formula (4) ;

[Wherein, m and n each independently represent an integer of 1 to 10. ]
Methacrylic acid ester or acrylic acid ester for forming the methacrylic acid ester unit or acrylic acid ester unit represented by the following formula (5)

[Wherein, R ₁ represents a hydrogen atom or a methyl group, and R ₂ represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms. ]
Is a fluorine-based resin obtained by graft copolymerization with
The coating material contains 1 to 40 parts by mass of fine particles and 1 to 15 parts by mass of conductive particles with respect to at least 100 parts by mass of the fluororesin.
The amount of the coating material is 0.3 to 4.0 parts by mass with respect to 100 parts by mass of the magnetic material-dispersed resin core.
A two-component developer, wherein the magnetic carrier has a contact angle of 95 to 125 °.

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