JPH06337539A - Development method - Google Patents

Abstract

(57) [Summary] [Structure] In a method of developing a latent image on an image carrier using a two-component developer comprising toner particles and a magnetic carrier, the toner contains at least a thermoplastic resin and a colorant. 1. A capsule toner composed of a heat-fusible core material and an outer shell provided so as to cover the surface of the core material. The outer shell is a capsule toner whose main component is amorphous polyester, and the carrier has an apparent density of 1. 7g / cm ³ or less or saturation magnetization 6
A development method characterized in that the carrier is a ferrite or magnetite carrier of 0 emu / g or less. [Effect] By using a two-component developer containing a carrier having a predetermined apparent density and saturation magnetization in the present invention, development suitable for the capsule toner of the present invention can be carried out, and low energy fixing and development The life can be extended.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing method used in plain paper copying machines, laser printers, plain paper facsimiles and the like. More specifically, the present invention relates to a method of developing an electrostatic charge image suitable for a reprographic system that employs a magnetic brush development method, when an encapsulated toner whose outer shell is composed of amorphous polyester is used as the toner. The present invention relates to a developing method using a two-component developer used in a magnetic brush developing system.

[0002]

2. Description of the Related Art When an image is formed in a copying machine or a laser beam printer,
The Carlson method is generally used (US Pat. Nos. 2,221,776, 2,297,691 and 2,357,809; "Electro
photography ": p22-p41, RMShaffert 1965, The Focal P
ress). In electrophotography, an electrostatic latent image formed by optical means is first developed in a developing process and then transferred to a recording medium such as recording paper in a transferring process, and further, in a fixing process, generally high heat and high heat are applied. An image is formed by fixing with a fixing roller system having pressure. In such a conventional image forming method, the temperature of the heating element of the fixing device is extremely high and a large pressure is required during the process from the formation of the electrostatic latent image to the fixing to the recording medium. It is the current situation.

On the other hand, since the photoconductor and the developing device need to be kept at room temperature, it is necessary to keep a considerable distance between the fixing unit and the photoconductor and the developing device. It is necessary to remove the heat generated from the outside of the system. Noise and heat generated by the forced heat dissipation device are also a cause of environmental damage in offices and the like. The fixing step exists independently, usually at a high temperature of around 200 ° C. and at 2 Kg /
Since fixing is performed by a fixing device having a linear pressure of cm or more, expensive heat-resistant resin and heat-resistant rubber are required around the fixing device. Also, when fixing at such a high temperature, the paper curls,
It has been pointed out that troubles such as jamming are likely to occur, and the paper absorbs heat depending on the thickness of the paper, resulting in defective fixing.

Further, if the fixing temperature is high, it takes a long time to reach the set temperature, and quick printing cannot be performed. Therefore, it is not suitable for an apparatus such as a facsimile which requires quick printing. On the other hand, since it is not possible to expect the softening of the resin in the toner due to heat in the conventional toner which is going to be fixed at a fixing temperature of about 100 ° C. or less, fixing by plastic deformation of the resin becomes the main component, and a large amount of 5 Kg / cm or more is usually used. Linear pressure is required, and in that case, not only a large-scale fixing device is used, but also the fixing strength is inferior to that of heat fixing, and problems such as paper wrinkling occur.

From these viewpoints as well, development of a new system and a toner adapted thereto is expected. In order to meet such expectations, the present applicant has developed a capsule toner whose outer shell is made of amorphous polyester, and has already applied for a patent (Japanese Patent Application No. 4-259088). This capsule toner has excellent offset resistance and blocking resistance in the heat and pressure fixing method, can be fixed at a low temperature, and can form a clear image free from fog a number of times while being stable.
Since the thermal properties are greatly different from conventional toner,
Development of a developing method suitable for using the toner has been demanded.

The object of the present invention is, in order to solve the above problems, a two-component developer comprising toner particles and a magnetic carrier, which is particularly suitable when an encapsulated toner whose main shell is made of amorphous polyester is used. Another object of the present invention is to provide a developing method for developing a latent image on an image carrier by using.

[0007]

The summary of the present invention is as follows.
(1) In a method of developing a latent image on an image carrier using a two-component developer consisting of toner particles and a magnetic carrier,
The toner is composed of a heat-fusible core material containing at least a thermoplastic resin and a colorant, and an outer shell provided so as to cover the surface of the core material, and the main component of the outer shell is amorphous polyester. And a two-component developer comprising (2) toner particles and a magnetic carrier, wherein the carrier is a ferrite or magnetite carrier having an apparent density of 2.7 g / cm ³ or less. In a method of developing a latent image on an image carrier using the toner, the toner comprises a heat-fusible core material containing at least a thermoplastic resin and a colorant, and an outer shell provided so as to cover the surface of the core material. A capsule toner composed of an amorphous polyester whose main component is an outer shell, and the carrier is a ferrite carrier having a saturation magnetization of 60 emu / g or less. It relates to a developing method.

The toner used in the present invention is composed of a heat-fusible core material containing at least a thermoplastic resin and a colorant, and an outer shell provided so as to cover the surface of the core material. This is a capsule toner whose main component is amorphous polyester. The encapsulated toner is a toner having a shell having a property that the shell structure is weakened by heat and containing a core material that can be fixed by pressure at low temperature. That is, the shell structure is changed by heat, and the core material is released and fixed when pressure is applied.

The amorphous polyester, which is the main component of the outer shell, is usually one or more alcohol monomers (divalent,
Trivalent or higher) and one or more carboxylic acid monomers (divalent,
(3 or more), which is obtained by polycondensation, and is condensed using a monomer containing at least a trivalent or more polyvalent alcohol monomer and / or a trivalent or more polyvalent carboxylic acid monomer. It is obtained by polymerization (Japanese Patent Application No. 4-
259088). Such amorphous polyester is
It is usually contained in an amount of 50 to 100% by weight based on the total weight of the outer shell, and as other components contained in the outer shell, polyamide, polyesteramide, polyurea and the like can be used in an amount of 0 to 50% by weight.

Examples of the dihydric alcohol component include polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene (3.3) -2,
2-bis (4-hydroxyphenyl) propane, polyoxypropylene (2.0) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene (2.0) -polyoxyethylene (2.0) -2,2-bis (4-Hydroxyphenyl) propane, polyoxypropylene (6) -2,2-
Alkylene oxide adducts of bisphenol A such as bis (4-hydroxyphenyl) propane, ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, neopentyl Glycol, 1,4-butenediol, 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, bisphenol A, bisphenol A
Propylene adduct, bisphenol A ethylene adduct, hydrogenated bisphenol A and the like.

Examples of trihydric or higher alcohol components include sorbitol, 1,2,3,6-hexanetetrol, and 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 and the like can be mentioned. Trivalent alcohol is preferably used. In the present invention, these dihydric alcohol monomers and polyhydric alcohol monomers having a valence of 3 or more may be used alone or in combination.

The acid component is a carboxylic acid component and is a divalent monomer such as maleic acid, fumaric acid,
Citraconic acid, itaconic acid, glutaconic acid, phthalic acid,
Isophthalic acid, terephthalic acid, succinic acid, adipic acid,
Sebacic acid, azelaic acid, malonic acid, n-dodecenylsuccinic acid, n-dodecylsuccinic acid, n-octylsuccinic acid, isooctenylsuccinic acid, isooctylsuccinic acid,
And anhydrides of these acids, or lower alkyl esters.

Examples of the trivalent or higher carboxylic acid component include 1,2,4-benzenetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid and 1,2,4- Butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-
2-methylenecarboxypropane, 1,2,4-cyclohexanetricarboxylic acid, tetra (methylenecarboxyl)
Methane, 1,2,7,8-octanetetracarboxylic acid, pyromellitic acid, empol trimer acid and their acid anhydrides,
Lower alkyl ester and the like can be mentioned. Preferably 3
A valent carboxylic acid or its derivative is used. In the present invention, these divalent carboxylic acid monomers and 3
A single or a plurality of monomers may be used from the carboxylic acid monomers having a valency or higher.

The method for producing the amorphous polyester in the present invention is not particularly limited and can be produced by esterification or transesterification reaction using the above-mentioned monomer. Here, amorphous means a state having no definite melting point. In the present invention, when crystalline polyester is used, the amount of energy required for melting is large and the toner fixing property cannot be improved, which is not preferable.

The amorphous polyester used in the present invention preferably has a glass transition point of 50 to 80 ° C. If it is less than 50 ° C, the storage stability of the toner will be poor, and if it exceeds 80 ° C, the fixing property of the toner will be poor. In the present invention, the glass transition point is a differential scanning calorimeter (manufactured by Seiko Denshi Kogyo Co., Ltd.) and the temperature rising rate is 10 ° C./min.
The temperature at the intersection of the extension line of the base line below the glass transition point and the tangent line showing the maximum slope from the rising portion of the peak to the apex of the peak, when measured by.

The acid value of the amorphous polyester is 3
It is preferably -50 (KOHmg / g), more preferably 10-30 (KOHmg / g). Three
If it is less than (KOHmg / g), it becomes difficult for the amorphous polyester as the shell material to come out to the interface during the in-situ polymerization, so that the storage stability of the toner becomes poor, and 50 (KOHmg / g)
If it exceeds g), the polyester tends to move into the aqueous phase, resulting in poor production stability. Here, the acid value is measured according to JIS
This is due to K0070.

The capsule toner which is preferably used in the present invention and whose main shell is made of amorphous polyester is
It is produced by a known method such as the in situ polymerization method. This capsule toner is composed of a heat-meltable core material containing at least a thermoplastic resin and a colorant, and an outer shell provided so as to cover the surface of the core material.

Examples of the resin used as the main component of the heat-melting core material of the capsule toner in the present invention include thermoplastic resins such as polyester resin, polyester / polyamide resin, polyamide resin and vinyl resin, and preferably vinyl. Examples include resin. The glass transition point derived from the thermoplastic resin which is the main component of the heat-fusible core material is preferably 10 to 50 ° C., but when the glass transition point is less than 10 ° C., the storage stability of the capsule toner is low. If the temperature exceeds 50 ° C., the fixing strength of the capsule toner deteriorates, which is not preferable.

Among the above-mentioned thermoplastic resins, examples of the monomer constituting the vinyl resin include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene and p-ethylstyrene. , 2,4-
Styrene or styrene derivatives such as dimethylstyrene, p-chlorostyrene, vinylnaphthalene, etc., ethylenically unsaturated monoolefins such as ethylene, propylene, butylene, isobutylene, etc., such as vinyl chloride,
Vinyl esters such as vinyl bromide, vinyl fluoride, vinyl acetate, vinyl propionate, vinyl formate, vinyl caproate, etc., such as acrylic acid, methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, N-Butyl acrylate, isobutyl acrylate, t-butyl acrylate, amyl acrylate, cyclohexyl acrylate, n-octyl acrylate, isooctyl acrylate, decyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, acrylic acid Stearyl, methoxyethyl acrylate, acrylic acid 2-
Hydroxyethyl, glycidyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, α-chloromethyl acrylate, methacrylic acid, methyl methacrylate,
Ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, amyl methacrylate, cyclohexyl methacrylate, n-octyl methacrylate, isooctyl methacrylate, methacrylic acid. Decyl, lauryl methacrylate, methacrylic acid 2
-Ethylhexyl, stearyl methacrylate, methoxyethyl methacrylate, 2-hydroxyethyl methacrylate, glycidyl methacrylate, phenyl methacrylate,
Ethylenic monocarboxylic acids such as dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate and the like, and esters thereof such as ethylenic monocarboxylic acid substitution products such as acrylonitrile, methacrylonitrile, acrylamide, etc., such as ethylenic acid such as dimethyl maleate. Dicarboxylic acids and their substitution products, vinyl ketones such as vinyl methyl ketone, vinyl ethers such as vinyl methyl ether, vinylidene halides such as vinylidene chloride, eg N-
Examples thereof include N-vinyl compounds such as vinylpyrrole and N-vinylpyrrolidone.

Of the components constituting the resin for the core material according to the present invention, 50 to 90% by weight of styrene or a styrene derivative is used to form the main skeleton of the resin, and ethylenic is used to adjust the thermal characteristics such as the softening temperature of the resin. It is preferable to use 10 to 50% by weight of monocarboxylic acid or its ester because the glass transition point of the resin for core material can be easily controlled.

When a crosslinking agent is added to the monomer composition constituting the resin for the core material according to the present invention, for example, divinylbenzene, divinylnaphthalene, polyethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol diethylene. Acrylate, 1,3-
Butylene glycol dimethacrylate, 1,6-hexylene glycol dimethacrylate, neopentyl glycol dimethacrylate, dipropylene glycol dimethacrylate, polypropylene glycol dimethacrylate, 2,2'-bis (4-methacryloxydiethoxyphenyl) propane, 2 General crosslinking such as 2,2'-bis (4-acryloxydiethoxyphenyl) propane, trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, tetramethylolmethane tetraacrylate, dibromoneopentyl glycol dimethacrylate, diallyl phthalate Appropriate agent (2 if necessary
A combination of two or more species can be used.

The amount of these crosslinking agents used is 0.001 to 15% by weight, preferably 0.1 to 10% by weight, based on the polymerizable monomer. The amount of these crosslinkers used is 15
If it is more than 5% by weight, the toner is less likely to be melted by heat, resulting in poor heat fixing property or heat pressure fixing property. Also the amount used
If the amount is less than 0.001% by weight, it is difficult to prevent the offset phenomenon in which a part of the toner adheres to the roller surface without being completely fixed to the paper and is transferred to the next paper in the heat and pressure fixing. Further, the above monomer may be polymerized in the presence of unsaturated polyester to give a graft or crosslinked polymer, which may be used as a resin for the core material.

Further, as the polymerization initiator used when producing the thermoplastic resin for the core material, 2,2'-azobis (2,4
-Dimethylvaleronitrile), 2,2'-azobisisobutyronitrile, 1,1'-azobis (cyclohexane-1-carbonitrile), 2,2'-azobis-4-methoxy-2,4
-Dimethylvaleronitrile, other azo or diazo polymerization initiators: benzoyl peroxide, methyl ethyl ketone peroxide, isopropyl peroxycarbonate, cumene hydroperoxide, 2,4-dichlorobenzoyl peroxide, lauroyl peroxide, dicumyl peroxide Examples thereof include peroxide-based polymerization initiators such as oxides.

Two or more kinds of polymerization initiators may be mixed and used for the purpose of controlling the molecular weight and the molecular weight distribution of the polymer or the reaction time. The amount of the polymerization initiator used is 0.1 to 20 parts by weight, preferably 1 to 10 parts by weight, based on 100 parts by weight of the polymerized monomer.

In the present invention, the colorant is contained in the core material of the capsule toner, but all the dyes, pigments and the like used in the conventional colorant for toner can be used. Examples of the colorant used in the present invention include various carbon blacks produced by a thermal black method, an acetylene black method, a channel black method, a lamp black method, etc., and a grafted carbon black obtained by coating the surface of the carbon black with a resin. , Nigrosine dye, Phthalocyanine Blue, Permanent Brown FG, Brilliant First Scarlet, Pigment Green B, Rhodamine-B
Base, Solvent Red 49, Solvent Red 146,
Solvent Blue 35, etc., and mixtures thereof can be mentioned, and usually 1 to 15 per 100 parts by weight of resin in the core material.
Parts by weight are used.

In the present invention, a charge control agent may be further added to the core material, and the negatively chargeable charge control agent to be added is not particularly limited and may be, for example, a metal-containing azo dye "Vari. First Black 3804 "," Bontron S-31 "," Bontron S-32 "," Bontron S-34 "(above, manufactured by Orient Chemical Co., Ltd.)," Eisenspiron Black TVH "(manufactured by Hodogaya Chemical Co., Ltd.)
Etc., copper phthalocyanine dyes, metal complexes of alkyl derivatives of salicylic acid, such as “Bontron E-81”, “Bontron E-82”, “Bontron E-85” (above, manufactured by Orient Chemical Co.), quaternary ammonium salt, for example. "CO
PY CHARGE NX VP434 ”(manufactured by Hoechst), nitroimidazole derivatives and the like can be mentioned.

The positively chargeable charge control agent is not particularly limited, and examples thereof include a nigrosine dye "Nigrosine Base EX", "Oil Black BS", "Oil Black SO", "Bontron N-01", and "Bontron". N-07 "," Bontron N-11 "(above, manufactured by Orient Chemical Co., Ltd.), triphenylmethane dye containing a tertiary amine as a side chain, quaternary ammonium salt compound, for example," Bontron P-51 "( Orient Chemical Co., Ltd.),
Cetyl trimethyl ammonium bromide, "COPY CHARG
Examples thereof include EPX VP435 "(manufactured by Hoechst) and the like, and polyamine resins such as" AFP-B "(manufactured by Orient Chemical Co.) and imidazole derivatives. The above charge control agent is contained in the core material in an amount of 0.1 to 8.0% by weight, preferably 0.2 to 5.0% by weight.

In the core material, for the purpose of improving offset resistance in heat and pressure fixing, if necessary, for example, polyolefin, fatty acid metal salt, fatty acid ester, partially saponified fatty acid ester, higher fatty acid, higher alcohol, paraffin wax. Any one or more offset preventing agents such as amide wax, polyhydric alcohol ester, silicon varnish, aliphatic fluorocarbon, and silicone oil may be contained.

The polyolefin is, for example, a resin such as polypropylene, polyethylene, polybutene, etc., and has a softening point of 80 to 160 ° C. Examples of the fatty acid metal salt include maleic acid and zinc, magnesium,
Metal salts with calcium, etc .; Metal salts with stearic acid and zinc, cadmium, barium, lead, iron, nickel, cobalt, copper, aluminum, magnesium, etc .; Dibasic lead stearate; Oleic acid and zinc, magnesium, iron , Metal salts with cobalt, copper, lead, calcium, etc .; metal salts with palmitic acid, aluminum, calcium, etc .; caprylate; lead caproate; metal salts with linoleic acid, zinc, cobalt, etc .; calcium ricinoleate; Examples thereof include metal salts of ricinoleic acid and zinc, cadmium, and the like, and mixtures thereof. Examples of the fatty acid ester include maleic acid ethyl ester, maleic acid butyl ester, stearic acid methyl ester, stearic acid butyl ester, palmitic acid cetyl ester, montanic acid ethylene glycol ester and the like. Examples of the partially saponified fatty acid ester include partially saponified calcium of montanic acid ester. Examples of the higher fatty acid include dodecanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, ricinoleic acid, arachidic acid, behenic acid, lignoceric acid, ceracoleic acid, and mixtures thereof. You can Examples of the higher alcohols include dodecyl alcohol, lauryl alcohol, myristyl alcohol, palmityl alcohol, stearyl alcohol, aralkyl alcohol, and behenyl alcohol. Examples of the paraffin wax include natural paraffin, microwax, synthetic paraffin, and chlorinated hydrocarbon. Examples of the amide wax include stearic acid amide, oleic acid amide, palmitic acid amide, lauric acid amide, behenic acid amide, methylenebisstearamide, ethylenebisstearamide, N, N'-m-xylylenebis. Examples thereof include stearic acid amide, N, N'-m-xylylenebis-12-hydroxystearic acid amide, N, N'-isophthalic acid bisstearylamide, and N, N'-isophthalic acid bis-12-hydroxystearylamide. Examples of the polyhydric alcohol ester include glycerin stearate,
Glycerin ricinoleate, glycerin monobehenate,
Examples thereof include sorbitan monostearate, propylene glycol monostearate and sorbitan trioleate. Examples of the silicon varnish include methyl silicon varnish and phenyl silicon varnish. Examples of the aliphatic fluorocarbon include low-polymerization compounds of tetrafluoroethylene and propylene hexafluoride, and fluorine-containing surfactants described in JP-A-53-124428. The ratio of these offset preventing agents to the resin in the core material is preferably 1 to 20% by weight.

The method of manufacturing the capsule toner according to the present invention is in s in terms of simplification of manufacturing equipment and manufacturing process.
In situ polymerization is preferred, for example, mother particles as a core material and child particles of an outer shell forming material having a number average particle diameter of 1/8 or less of the number average particle diameter of the mother particles are stirred at high speed in an air stream. It may be performed by a dry method such as forming an outer shell.

The production method by the in situ polymerization method will be described below as an example. In this manufacturing method, the shell is formed by dispersing a mixed liquid of a core constituent material and an outer shell constituent material composed of amorphous polyester in a dispersion medium so that the shell constituent material is unevenly distributed on the surface of the droplet. Can be done using. That is, the core material-constituting material and the outer shell-constituting material are separated from each other in the droplets of the mixed solution due to the difference in solubility index, and in this state, the polymerization proceeds to form a capsule structure. According to this method, since the outer shell is formed as a layer made of amorphous polyester having a substantially uniform thickness, the toner has the characteristic that the charging characteristics are uniform.

In the case of this method, it is necessary to contain a dispersion stabilizer in the dispersion medium in order to prevent aggregation and coalescence of dispersoids. Examples of the dispersion stabilizer include gelatin, gelatin derivatives, polyvinyl alcohol, polystyrene sulfonic acid, hydroxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, sodium carboxymethyl cellulose, sodium polyacrylate, sodium dodecylbenzene sulfonate, sodium tetradecyl sulfate, and pentadecyl sulfate. Sodium, sodium octyl sulfate, sodium allyl-alkyl-polyethersulfonate, sodium oleate, sodium laurate, sodium caprate, sodium caprylate, sodium caproate, potassium stearate, calcium oleate, 3,3-disulfonediphenyl Urea-4,4-diazo-bis-amino-β-
Naphthol-6-sulfonate, ortho-carboxybenzene-azo-dimethylaniline, 2,2,5,5-
Tetramethyl-triphenylmethane-4,4-diazo-bis-β-naphthol-sodium disulfonate, colloidal silica, alumina, tricalcium phosphate, ferric hydroxide, titanium hydroxide, aluminum hydroxide and others are used. can do. Two or more kinds of these dispersion stabilizers may be used in combination.

Examples of the dispersion medium of the dispersion stabilizer include water, methanol, ethanol, propanol, butanol, ethylene glycol, glycerin, acetonitrile, acetone, isopropyl ether, tetrahydrofuran and dioxane. It is also possible to use these individually or in mixture.

In the production method of the present invention, the amount of the amorphous polyester added is usually 3 to 50 parts by weight, preferably 5 to 40 parts by weight, based on 100 parts by weight of the core material. If it is less than 3 parts by weight, the film thickness of the outer shell becomes too thin and the storage stability deteriorates. If it exceeds 50 parts by weight, the viscosity becomes high and atomization becomes difficult and the production stability deteriorates.

In the present invention, the encapsulated toner obtained as described above may be used as a precursor particle, and a heat-pressure fixing encapsulated toner further subjected to seed polymerization may be used. Therefore, in the present invention, the encapsulated toner includes not only those obtained by the in situ polymerization method alone as described above but also those obtained by combining the in situ polymerization and the seed polymerization.

That is, seed polymerization is carried out by adding at least a vinyl polymerizable monomer and a vinyl polymerization initiator to an aqueous suspension of the capsule toner (hereinafter sometimes referred to as precursor particles) obtained as described above. After being absorbed in the precursor particles, the monomer components in the precursor particles are polymerized. For example, after the production of the precursor particles by the above-mentioned in situ polymerization method, at least the vinyl polymerizable monomer and the vinyl polymerization initiator are immediately added to the precursor particles in a suspended state so as to be absorbed in the precursor particles. Seed the monomer component in the particles
It may be polymerized. By doing so, the manufacturing process can be further simplified. The vinyl polymerizable monomer or the like to be absorbed in the precursor particles may be added in advance as a water emulsion.

The water emulsion to be added is obtained by emulsifying and dispersing a vinyl polymerizable monomer and a vinyl polymerization initiator in water together with a dispersion stabilizer. In addition, a crosslinking agent, an offset preventing agent, a charge control agent, etc. Can also be included.

The vinyl polymerizable monomer used in the seed polymerization may be the same as that used in the production of the above-mentioned precursor particles. Further, as the vinyl polymerization initiator, the cross-linking agent and the dispersion stabilizer, the same ones as those used in the production of the precursor particles can be used. seed
The amount of the crosslinking agent used in the polymerization is 0.001 to 15% by weight, preferably 0.1 to 15% by weight based on the vinyl polymerizable monomer.
It is recommended to use 10% by weight. When the amount of these cross-linking agents used is more than 15% by weight, the toner obtained is less likely to be melted by heat, resulting in poor heat fixing property or heat pressure fixing property.
When the amount used is less than 0.001% by weight, it is difficult to prevent the offset phenomenon in which a part of the toner adheres to the roller surface without being completely fixed to the paper and is transferred to the next paper during thermal pressure fixing.

In order to further improve the storage stability of the toner, the above-mentioned amorphous polyester may be added to the water emulsion. The amount added at that time is usually 1 to 20 parts by weight, preferably 3 to 15 parts by weight, based on 100 parts by weight of the core material. In addition to the amorphous polyester which is the main component of the outer shell, for example, a carboxyl group, an acid anhydride group, a hydroxyl group,
A vinyl resin having a hydrophilic functional group such as an amino group or ammonium ion, an amorphous polyesteramide, an amorphous polyamide, or an epoxy resin may be used in combination. Such a water emulsion can be prepared by uniformly dispersing it with an ultrasonic oscillator or the like.

The acid value of the amorphous polyester added by seed polymerization is in situ polymerization (first stage reaction).
It is preferably 3 to 50 (KOHmg / g), and more preferably 10 to 30 (KOHmg / g) as in the case of.
g). When it is less than 3 (KOHmg / g), the amorphous polyester as the shell material is less likely to exist at the interface during seed polymerization, and the storage stability of the obtained toner is poor,
When it exceeds 50 (KOHmg / g), the polyester is apt to migrate to the aqueous phase and the production stability deteriorates. Here, the method for measuring the acid value is according to JIS K0070.

The water emulsion is added in such an amount that the vinyl polymerizable monomer is used in an amount of 10 to 20 with respect to 100 parts by weight of the precursor particles.
Adjust so that it is 0 parts by weight. If it is less than 10 parts by weight, the fixing property is not improved, and if it exceeds 200 parts by weight, it becomes difficult to uniformly absorb the monomer in the precursor particles.

By the addition of the above water emulsion, the vinyl polymerizable monomer is absorbed in the precursor particles and the precursor particles swell. Then, in this state, the monomer component in the precursor particles is polymerized. That is, using the precursor particles as seed particles
ed polymerization.

When seed polymerization is further carried out in this manner, the following points are further improved as compared with the capsule toner produced by the in situ polymerization method alone.

That is, the encapsulated toner produced by the in situ polymerization method is superior to the conventional one in terms of low temperature fixing property and storage stability, but by further performing the seed polymerization method, the outer shell having a more uniform interface is obtained. Are formed, and the storage stability is further improved. In addition, the polymerizable monomer of the core material can be polymerized in two stages (in situ polymerization reaction and seed polymerization reaction),
By appropriately using a cross-linking agent, it becomes easy to control the molecular weight of the thermoplastic resin in the core material, and it is possible to further improve low-temperature fixability and offset resistance. In particular, it is possible to provide a toner suitable not only for high-speed fixing but also for low-speed fixing.

For the purpose of charge control, an appropriate amount of the charge control agent as exemplified above may be added to the outer shell material of the capsule toner of the present invention, or this charge control agent may be mixed with the toner. However, even if they are added, the addition amount can be small because the chargeability is controlled by the outer shell itself.

The particle size of the capsule toner in the present invention is not particularly limited, but the average particle size is usually 3 to 30 μm. The thickness of the outer shell of the capsule toner is 0.
01 to 1 μm is preferable, and if it is less than 0.01 μm, blocking resistance is deteriorated, and if it exceeds 1 μm, heat melting property is deteriorated, which is not preferable.

If desired, a fluidity improver, a cleaning property improver, etc. can be used in the capsule toner of the present invention. Examples of the fluidity improver include silica, alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, silica sand, clay, mica, wollastonite, diatomaceous earth, and chromium oxide. , Cerium oxide, red iron oxide, antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silicon carbide, silicon nitride and the like. Fine silica powder is particularly preferable.

The silica fine powder is Si--O--Si.
It is a fine powder having a bond and may be produced by a dry method or a wet method. In addition to anhydrous silicon dioxide, aluminum silicate, sodium silicate,
It may be any of potassium silicate, magnesium silicate, zinc silicate, etc., but those containing 85% by weight or more of SiO ₂ are preferable. Further, a fine powder of silica surface-treated with a silane coupling agent, a titanium coupling agent, a silicone oil, a silicone oil having an amine in a side chain, or the like can be used.

Examples of the cleaning property improver include metal salts of higher fatty acids typified by zinc stearate, fine particles of fluorine-based high molecular weight particles, and the like. Further additives for adjusting the developability, for example, methacrylic acid methyl ester,
Fine particles of a polymer such as methacrylic acid butyl ester may be used.

Further, a small amount of carbon black may be used for toning and resistance adjustment. As the carbon black, conventionally known ones, for example, various ones such as furnace black, channel black and acetylene black can be used.

Carrier particles used in the magnetic brush development method are generally ore reduced iron powder produced by reducing iron ore, mill scale reduced iron powder produced by reducing mill scale, and molten copper are fine pores. Conventionally used are spherical atomized iron powder that has flowed out of the powder and is cooled and powdered, iron nitride powder that is obtained by nitriding copper flakes, crushing them, and then denitrifying them. Further, a ferrite carrier obtained by granulating / drying and firing a ferrite powder containing Fe ₂ O ₃ as a main raw material is also used.

Since the iron powder type carrier is oxidized by moisture in the air and Fe ₂ O ₃ so-called rust is generated on the surface, it is covered with a stable oxide thin film having a relatively high resistance by forced oxidation. The electric resistance can be adjusted. The iron powder type carrier has a lower resistance than the ferrite carrier and is easy to produce an image density, but has a large true specific gravity and a low fluidity, so that the developer life is generally inferior to that of the ferrite carrier.

On the other hand, the ferrite carrier has a true specific gravity of 30 to 40% smaller than that of the iron powder type carrier, the electric resistance and magnetic characteristics can be widely controlled, and it is spherical and has good fluidity and little residual magnetization. It has features such as being able to. Therefore, the ferrite carrier is easier to adjust the image than the iron powder type carrier and is suitable for extending the life of the developer, but has not yet reached the level enough to satisfy the demand.

Further, it is necessary to consider the performance of the core particles and the performance of the toner in order to extend the life of the developer.
That is, when ferrite carriers are used as core particles, Fe ₂ O ₃ , NiO, CuO, CoO, which are raw materials of ferrite,
MgO, ZnO, NiCO ₃ , MnCO ₃ , BaC
It is necessary to select a material such as O ₃ , SrCO ₃ , Li ₂ CO ₃ , and CdO in which the composition ratio and composition uniformity are important and the chemical change is small.

Magnetite (Fe ₂ O ₃ ) is also a kind of ferrite, and is also called iron ferrite. 100% of Fe ₂ O ₃ is used as a raw material, and a carrier is produced from this using a dry method similar to the production of ferrite described later. The magnetite carrier has magnetic characteristics, especially maximum magnetization larger than that of ferrite, and FeO having a low resistance inside the carrier. FeO has a relatively low resistance. Since its performance is similar to that of a ferrite type, it is effective for a reversal development type developer having a small effective development potential width, and has recently attracted attention.

The core particles that can be used in the present invention are magnetite carriers or ferrite carriers, and other than Fe ₂ O ₃ , NiO, CuO, CoO,
MgO, ZnO, NiCO ₃ , MnCO ₃ , BaC
Raw materials such as O ₃ , SrCO ₃ , Li ₂ CO ₃ , and CdO are used. In addition, as additives, SiO ₂ , CaCO ₃ , T
iO ₂ , SnO ₂ , PbO, V ₂ O ₅ , Bi ₂ O ₅ , A
It is also possible to use l ₂ O ₃ or the like.

The ferrite carrier is generally manufactured by a dry method in which raw materials are mechanically mixed, calcined and finely pulverized, and then granulated and sintered at a high temperature. That is, some metal oxides of the main raw material are mixed with other metal oxides as an additive as the case may be, then dried and baked, and then a binder such as polyvinyl alcohol, a defoaming agent, a dispersant, etc. Add slurry for granulation. Granules obtained by atomizing and drying the slurry are heated to 900-1 in an electric furnace.
After firing at 300 ° C., crushing and classification are performed to produce core particles.

In the present invention, among the above carriers, the apparent density is 2.7 g / cm ³ for the reason described below.
The following or those having a saturation magnetization of 60 emu / g or less are used. In the present invention, one of these conditions may be satisfied, but one satisfying both of these conditions, that is, the apparent density is 2.7 g / cm ³ or less,
Further, those having a saturation magnetization of 60 emu / g or less are more preferably used.

The apparent density of the carrier is JIS-Z25.
It is measured by a measuring method according to 04 (Apparent Density Testing Method for Metal Powder). Generally, the apparent density of ferrite carrier or magnetite carrier is 2.5 to 3.5 (g /
cm ³ ), which is slightly lighter than the iron powder carrier of 2.5 to 4.5. However the apparent density of the carrier used in the present invention is small, typically less than 2.7 g / cm ³ preferably requires 2.0~2.6g / cm ^3. When the apparent density exceeds 2.7 g / cm ³ , the force applied to the toner becomes too large and the shell of the capsule toner used in the present invention is easily damaged. On the other hand, if the density is less than 2.0 g / cm ³ , then undesired phenomena occur such that the saturation magnetization is too low, the strength of the carrier is lost, the carrier is easily damaged in the developing tank, and the carrier is easily scattered. Therefore, 2.0 g / cm ³ or more is preferable.

Such a low apparent density carrier has a particle size of the metal oxide as a raw material in the manufacture of the carrier, the type and amount of the dispersant and the binder, the addition of the extender, the conditions for slurry formation, and the powder mist drying. It can be achieved by controlling the conditions and firing conditions.

The saturation magnetization of the carrier was determined to be 14 KO by a vibration capacitance magnetometer (VSMP-1 manufactured by Toei Industry Co., Ltd.).
Although it is measured under the condition when set to e, the saturation magnetization of the ferrite carrier is usually 50 to 80 (emu /
g), which is smaller than the iron powder carriers 150 to 210. However, the carrier used in the present invention has a small saturation magnetization and is usually 60 emu / g or less, preferably 30 to
Requires 55 emu / g. Saturation magnetization is 60 emu /
When it exceeds g, the force applied to the toner becomes too large, and the shell of the capsule toner used in the present invention is easily damaged. When the saturation magnetization is less than 30 emu / g, the fluidity of the developer is reduced, the charge amount does not rise rapidly, and toner is blown out from the developing tank.
An unfavorable phenomenon such as easy carrier scattering may occur, and 30 emu / g or more is preferable.

Such a carrier having a low saturation magnetization is used as a starting material in the production of a carrier, as a particle size of a metal oxide, a dispersant,
This can be achieved by controlling the type and amount of the binder, the addition of the extender, the conditions for slurrying, the conditions for powder mist drying, the firing conditions, and the like. The saturation magnetization of the carrier mainly depends on the composition, and the saturation magnetization decreases as the contents of Mn and Fe increase.

Further, a resin-coated carrier in which a resin coating layer is provided on the surface of core particles such as a ferrite carrier and a magnetite carrier has been devised, and the toner adheres to the surface of the carrier particles to make the charging of the toner unstable. Has been recently attracting attention because it has the potential of further improving the durability of the developer, adjusting the triboelectric charging property of the toner, and reducing the environmental dependence of charging characteristics. . The performance required for the resin material for coating is that the coating layer on the surface of the core particles has sufficient abrasion resistance and heat resistance, and that the coating layer has sufficient adhesion to the core particles. Further, it is required that the coating layer has a good anti-sticking property so that the toner particles do not stick to the surface of the carrier particles, and that the toner is easily imparted with the desired polarity and magnitude of chargeability. As the resin material, a fluororesin, an acrylic resin, a styrene acrylic resin, a silicone resin, a polyester resin, a polybutadiene resin or the like is used, and an acrylic resin or a silicone resin is preferable.

The method for coating the carrier is to dissolve the resin in an organic solvent or the like, or use a solution prepared by forming an aqueous resin emulsion, and apply the solution to the particle surface by the dipping method, the atomization method or the like.
The thickness is usually 0.1 μm due to drying and / or heat curing.
Generally, a resin film having a thickness of 1.0 μm is formed. However, as the coated carrier used for the capsule toner in the present invention, a coating layer having a thickness of 1.0 μm or more is usually used. Coating layer thickness is 1.0 μm
If the amount is less than enough to smooth the surface irregularities of the carrier, the fluidity becomes low and the force applied to the capsule toner becomes large, so that the shell is easily worn and damaged, and the developer life is shortened. Not preferable. On the other hand, the coat layer of the carrier is worn by the sleeve on the magnet roll in the developing unit, but by thickening the coating layer, the fluidity is improved and the reduction of the film thickness due to abrasion can be suppressed, which is effective in extending the service life. . Therefore, it is more preferably 2.0 μm or more. On the other hand, thickening the coating layer requires coating the resin multiple times or increasing the concentration of the resin solution.In the former case, the manufacturing process is complicated, and in the latter case, non-uniformity of the coating film is a problem. Therefore, the thickness of the coating layer is practically 5.0 μm.

When the developing method of the present invention is carried out using a two-component developer comprising the above-mentioned capsule toner of the present invention and a carrier having the above-mentioned apparent density or saturation magnetization, a developing device used and As a method, a conventionally known method can be used as it is.
That is, a normal developing method in which toner having a polarity opposite to that of the latent image on the image carrier is developed by Coulomb force, and toner having the same polarity as the latent image on the image carrier is applied with a bias voltage to utilize Coulomb repulsion force. The latent image on the image carrier can be developed by a reversal development method of developing. In this case, the compounding amount of the toner particles and the carrier is usually 1/99 to 20/80.

The developing method of the present invention can be used for developing a latent image formed on a photoconductor as an image bearing member, a latent image formed on a dielectric or the like. After the developing process is completed by the developing method of the present invention as described above, the toner image is transferred and fixed on a recording medium such as recording paper by a conventionally known method.

[0067]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

Capsule Toner Production Example 1 Propylene oxide adduct 36 of bisphenol A
7.5 g, bisphenol A ethylene oxide adduct 146.4 g, terephthalic acid 126.0 g, dodecenyl succinic anhydride 40.2 g, trimellitic anhydride 77.
7 g was placed in a glass 2-liter four-necked flask, equipped with a thermometer, a stainless stirrer, a downflow condenser, and a nitrogen introduction tube, and allowed to react at 220 ° C. in a mantle heater under a nitrogen stream. .

The degree of polymerization was traced from the softening point according to ASTM E28-67, and the reaction was terminated when the softening point reached 110 ° C. The resin obtained at this time was replaced with resin A
And The glass transition point of this resin was measured by a differential scanning calorimeter (manufactured by Seiko Denshi Kogyo KK) and found to be 65 ° C. In addition, the softening point and acid value were measured, and each was 1
It was 10 ° C. and 18 KOH mg / g. The acid value was measured by a method according to JIS K0070.

69.0 parts by weight of styrene, 31.0 parts by weight of 2-ethylhexyl acrylate, 0.9 parts by weight of divinylbenzene, 7.0 parts by weight of carbon black "# 44" (manufactured by Mitsubishi Kasei Co.), 20 parts by weight of Resin A and 2,2 '. -Azobisisobutyronitrile (3.5 parts by weight) was added, and the mixture was put into an attritor (Mitsui Miike Kakoki Co., Ltd.) and dispersed at 10 ° C for 5 hours to obtain a polymerizable composition. Then, 240 g of the above polymerizable composition was added to 560 g of an aqueous colloidal solution containing 4% by weight of tricalcium phosphate prepared in advance in a 2 liter glass separable flask, and TK homomixer (made by Tokushu Kika Kogyo Co., Ltd. ) Was used for 5 minutes at 5 ° C. and a rotation speed of 12000 rpm.

Next, a 4-port glass lid was attached, a reflux cooling tube, a thermometer, a nitrogen introduction tube, and a stainless steel stirring rod were attached and the lid was placed in an electric heating mantle heater. While continuing stirring under nitrogen, the temperature was raised to 85 ° C. and the reaction was performed for 10 hours. After cooling, dissolve the dispersion medium with 10% aqueous hydrochloric acid, filter, wash with water, dry under reduced pressure at 20 mmHg for 12 hours at 45 ° C, classify with a wind classifier, and remove the outer shell with an average particle size of 8 μm. A capsule toner which is a crystalline polyester was obtained.

To 100 parts by weight of this capsule toner, 0.4 parts by weight of hydrophobic silica fine powder "Aerosil R-972" (manufactured by Nippon Aerosil Co., Ltd.) was added and mixed to obtain a capsule toner of the present invention. This is designated as Toner 1. The glass transition point derived from the resin in the core material was 30.6 ° C, and the softening point of Toner 1 was 125.5 ° C.

Capsule Toner Production Example 2 Propylene oxide adduct 52 of bisphenol A
5.0 g, terephthalic acid 138.6 g, and dodecenyl succinic anhydride 160.8 g were put into a glass 2-liter four-necked flask, and a thermometer, a stainless stir bar, a downflow condenser, and a nitrogen introduction tube were attached, and a mantle was attached. The reaction was carried out at 220 ° C. in a heater under a nitrogen stream.

The degree of polymerization was traced from the softening point according to ASTM E28-67, and the reaction was terminated when the softening point reached 110 ° C. The resin obtained at this time is referred to as resin B
And The glass transition point of this resin was 63 ° C. when measured with a differential scanning calorimeter (manufactured by Seiko Denshi Kogyo KK). In addition, the softening point and acid value were measured, and each was 1
It was 10 ° C. and 10 KOH mg / g. The acid value was measured by a method according to JIS K0070.

75 parts by weight of styrene and 25 parts by weight of n-butyl acrylate, softening point 75.3 ° C., glass transition point 40.5
Copper phthalocyanine "Sumikapr
intCyanine Blue GN-0 ”(Sumitomo Chemical Co., Ltd.) 6 parts by weight,
Resin B 15 parts by weight, polypropylene wax "Biscol
5 parts by weight of "550P" (manufactured by Sanyo Kasei Co., Ltd.) were premixed, melt-kneaded by a twin-screw extruder, cooled, and then pulverized. 40 parts by weight of this kneaded material, 50 parts by weight of styrene, n-
15 parts by weight of butyl acrylate and 2.5 parts by weight of 2,2'-azobisisobutylnitrile were mixed to obtain a polymerizable composition.
Next, 2 parts of the above polymerizable composition was added to 560 g of an aqueous colloidal solution containing 4% by weight of tricalcium phosphate, which had been prepared in advance in a 2 liter glass separable flask.
40 g was added, and the mixture was emulsified and dispersed for 2 minutes at 5 ° C. and a rotation speed of 12000 rpm using a TK homomixer.

Next, a 4-port glass lid was attached, a reflux cooling tube, a thermometer, a nitrogen introducing tube, and a stainless steel stirring rod were attached, and the glass was placed in an electric heating mantle heater. While continuing stirring under nitrogen, the temperature was raised to 85 ° C. and the reaction was performed for 10 hours. After cooling, dissolve the dispersion medium with 10% aqueous hydrochloric acid, filter, wash with water, dry under reduced pressure at 20 mmHg for 12 hours at 45 ° C, classify with a wind classifier, and remove the outer shell with an average particle size of 8 μm. A capsule toner which is a crystalline polyester was obtained.

To 100 parts by weight of this capsule toner, 0.4 parts by weight of hydrophobic silica fine powder "Aerosil R-972" (manufactured by Nippon Aerosil Co., Ltd.) was added and mixed to obtain a capsule toner of the present invention. This is designated as toner 2. The glass transition point derived from the resin in the core material was 33.2 ° C, and the softening point of Toner 2 was 122.8 ° C.

Capsule Toner Production Example 3 To 69.0 parts by weight of styrene, 31.0 parts by weight of 2-ethylhexyl acrylate, 6.0 parts by weight of 2,2'-azobisisobutyronitrile, and 0.8 parts by weight of divinylbenzene. 15.0 parts by weight of the resin A was added to dissolve the resin A. Carbon black "GPE-3" (made by Ryoyu Kogyo Co., Ltd.) grafted with styrene after the resin A was dissolved
20 parts by weight was added and dispersed for 1 hour with a magnetic stirrer to obtain a polymerizable composition. Then, 240 g of the above polymerizable composition was added to 560 g of an aqueous colloidal solution containing 4% by weight of tricalcium phosphate prepared in a 2 liter glass separable flask and emulsified and dispersed using a TK homomixer. .

Then, a four-necked glass lid was attached, a reflux cooling tube, a thermometer, a nitrogen introducing tube, and a stainless steel stirring rod were attached, and the apparatus was installed in an electric heating mantle heater, and stirring was continued under nitrogen. As the first stage polymerization, the temperature was raised to 85 ° C,
Polymerize for 10 hours to form seed particles, cool to room temperature,
Precursor particles were obtained.

Then, in an aqueous suspension of the precursor particles,
26.0 parts by weight of styrene, 14.0 parts by weight of 2-ethylhexyl acrylate, 2,2'-azobisisobutyronitrile 1 prepared by an ultrasonic oscillator (US-150, manufactured by Nippon Seiki Seisakusho Co., Ltd.) Emulsion solution 122.6 consisting of 0.6 parts by weight, divinylbenzene 0.8 parts by weight, sodium lauryl sulfate 0.2 parts by weight, and water 80 parts by weight.
A part by weight was added dropwise, and while continuing stirring under nitrogen, the temperature was raised to 85 ° C. as the second stage polymerization and reacted for 10 hours.
After cooling, dissolve the dispersion medium with 10% hydrochloric acid aqueous solution, filter, wash with water, air-dry, then dry under reduced pressure at 20 mmHg for 12 hours at 45 ° C., classify with an air classifier, and an outer shell with an average particle size of 8 μm is obtained. An amorphous polyester capsule toner was obtained.

To 100 parts by weight of this capsule toner, 0.4 parts by weight of hydrophobic silica fine powder "Aerosil R-972" was added and mixed to obtain an encapsulated toner of the present invention. This is designated as toner 3. The glass transition point derived from the resin in the core material was 35.6 ° C, and the softening point of Toner 3 was 122.0 ° C.

Carrier Production Example 1 Fe ₂ O ₃ 53 mol%, ZnO 32 mol%, CuO 15
Mol% was pulverized and mixed by a wet ball mill for 10 hours, dried, and then kept at 950 ° C. for 4 hours. This was crushed with a wet ball mill for 24 hours to 3 μm or less. The slurry is granulated and dried, then 1200 ° C. in a nitrogen atmosphere in an electric furnace,
After holding for 6 hours, it was pulverized and classified to 60 to 100 μm. When the magnetic characteristics of this granulated ferrite carrier were measured, the value of magnetization at 3000 Oe was 55 emu, and the coercive force and residual magnetization were 0. Moreover, the apparent density was 2.5.

Carrier Production Example 2 Fe ₂ O ₃ was ground and mixed in a wet ball mill for 10 hours,
After drying, it was kept at 950 ° C. for 4 hours. This was pulverized with a wet ball mill for 24 hours to have a size of 5 μm or less. The slurry is granulated and dried, and then 1200 ° C. in a nitrogen atmosphere in an electric furnace.
After holding at ℃ for 6 hours, crush and classify to 60-100μ
m. When the magnetic characteristics of this granulated magnetite carrier were measured, the value of magnetization at 3000 Oe was 55 emu.
And the coercive force and remanent magnetization were zero. Moreover, the apparent density was 2.7.

Carrier Production Example 3 Fe ₂ O ₃ 69 mol%, ZnO 16 mol%, CuO 15
Mol% was pulverized and mixed by a wet ball mill for 10 hours, dried, and then kept at 950 ° C. for 4 hours. This was pulverized with a wet ball mill for 24 hours to have a size of 5 μm or less. The slurry is granulated and dried, then 1200 ° C. in a nitrogen atmosphere in an electric furnace,
After holding for 6 hours, it was pulverized and classified to 60 to 100 μm. When the magnetic characteristics of this granulated ferrite carrier were measured, the value of magnetization at 3000 Oe was 48 emu, and the coercive force and residual magnetization were 0. Moreover, the apparent density was 2.5.

Carrier Production Example 4 Fe ₂ O ₃ was ground and mixed in a wet ball mill for 10 hours,
After drying, it was kept at 950 ° C. for 4 hours. This was pulverized with a wet ball mill for 24 hours to have a size of 5 μm or less. The slurry is granulated and dried, and then 1200 ° C. in a nitrogen atmosphere in an electric furnace.
After holding at ℃ for 6 hours, crush and classify to 60-100μ
m. When the magnetic properties of this granulated magnetite carrier were measured, the value of magnetization at 3000 Oe was 50 emu.
And the coercive force and remanent magnetization were zero. Moreover, the apparent density was 2.7.

Coated Carrier Production Example 1 Using the ferrite carrier obtained in Carrier Production Example 1, 12% by weight of the coating silicone resin composition was coated on the carrier using a fluidized bed, and further 15
Baking was performed at 0 ° C. for 3 hours to obtain a resin-coated carrier. The apparent density of the resin-coated carrier is 2.40 g.
/ Cm ³ , the resistance was 3 × 10 ¹² Ωcm, and the saturation magnetization was 55 emu / g. Further, the thickness of the coating material of the coated carrier was calculated by measuring the total weight of the coating material with a carbon analyzer and found to be 1.5 μm.

Coated Carrier Production Example 2 Using the magnetite carrier obtained in Carrier Production Example 2, 12% by weight of the acrylic resin composition for coating was coated on the carrier using a fluidized bed, and further 15
Baking was performed at 0 ° C. for 3 hours to obtain a resin-coated carrier. The apparent density of the resin-coated carrier is 2.60 g /
cm ³ , resistance was 4 × 10 ¹² Ωcm, and saturation magnetization was 84 emu / g. Further, the thickness of the coating material of the coated carrier was calculated by measuring the total weight of the coating material with a carbon analyzer and found to be 1.5 μm.

Coated Carrier Production Example 3 Using the ferrite carrier obtained in Carrier Production Example 3, 15% by weight of the amine-modified silicone resin composition for coating was coated on the carrier using a fluidized bed, and further at 150 ° C. After baking for 3 hours, a resin-coated carrier was obtained. The apparent density of the resin-coated carrier was 2.40 g / cm ³ , the resistance was 3 × 10 ¹² Ωcm, and the saturation magnetization was 48 emu / g. Further, the thickness of the coating material of the coated carrier was calculated to be 1.8 μm by calculating the total coating material weight with a carbon analyzer.

Coated Carrier Production Example 4 Using the magnetite carrier obtained in Carrier Production Example 4, the urethane-modified silicone resin composition for coating was coated on the carrier at 15% by weight using a fluidized bed, and further at 150 ° C. After baking for 3 hours, a resin-coated carrier was obtained. The apparent density of the resin-coated carrier was 2.60 g / cm ³ , the resistance was 2 × 10 ¹² Ωcm, and the saturation magnetization was 86 emu / g. Further, the thickness of the coating material of the coated carrier was calculated to be 1.8 μm by calculating the total coating material weight with a carbon analyzer.

Example 1 92 parts by weight of the resin-coated carrier obtained in Production Example 1 of coated carrier was mixed with 8 parts by weight of the encapsulated toner obtained in Production Example 1 of encapsulated toner, and the mixture was mixed with V blender to about 8 parts by weight.
The mixture was stirred for an hour to obtain a developer. Using the above-mentioned developer and intermittently replenishing the capsule toner, copying was carried out by a commercially available OPC-equipped digital copier equipped with a stirrer at a copying speed of 12 sheets / min.
No deterioration of the image was observed even after the development of 10,000 sheets, and a copy of good image quality was obtained. When the fixing property of the toner was evaluated by a gauze rubbing test, the toner was found to be sufficiently fixed at a heat roller surface temperature of 100 ° C.

Example 2 92 parts by weight of the resin-coated carrier obtained in the coated carrier production example 2 was mixed with 8 parts by weight of the encapsulated toner obtained in the capsule toner production example 2, and about 8 parts by a V blender were mixed.
The mixture was stirred for an hour to obtain a developer. When the above-mentioned developer was used and intermittently replenishing the capsule toner, copying was carried out by a commercially available OPC-equipped digital copier similar to that of Example 1 equipped with an agitator. No deterioration of the image was observed even after the operation, and a copy with good image quality was obtained.

Example 3 92 parts by weight of the resin-coated carrier obtained in Production Example 3 of coated carrier was mixed with 8 parts by weight of the encapsulated toner obtained in Production Example 1 of encapsulated toner, and the mixture was mixed with a V blender to about 8 parts by weight.
The mixture was stirred for an hour to obtain a developer. Using the above-mentioned developer and intermittently replenishing the capsule toner, copying was carried out by a commercially available OPC-equipped digital copier equipped with a stirrer at a copying speed of 12 sheets / min.
No deterioration of the image was observed even after the development of 10,000 sheets, and a copy of good image quality was obtained. Further, when the fixing property of the toner was evaluated by a gauze rubbing test, the toner was sufficiently fixed at a heat roller surface temperature of 100 ° C.

Example 4 92 parts by weight of the resin-coated carrier obtained in Production Example 4 of coated carrier was mixed with 8 parts by weight of the encapsulated toner obtained in Production Example 2 of encapsulated toner, and mixed with V blender to about 8 parts.
The mixture was stirred for an hour to obtain a developer. When the above-mentioned developer was used and intermittently replenishing the capsule toner, copying was carried out with a commercially available OPC-equipped digital copier similar to that of Example 1 equipped with a stirrer. No deterioration of the image was observed even after the operation, and a copy with good image quality was obtained.

Example 5 92 parts by weight of the resin-coated carrier obtained in Production Example 3 of coated carrier was mixed with 8 parts by weight of the encapsulated toner obtained in Production Example 3 of encapsulated toner, and mixed with V blender to about 8 parts by weight.
The mixture was stirred for an hour to obtain a developer. Using the above-mentioned developer and intermittently replenishing the capsule toner, copying was carried out by a digital copier equipped with a stirrer at a copying speed of 12 sheets / min and equipped with a commercially available OPC.
No deterioration of the image was observed even after the development of 10,000 sheets, and a copy of good image quality was obtained. Further, when the fixing property of the toner was evaluated by a gauze rubbing test, the toner was sufficiently fixed at a heat roller surface temperature of 100 ° C.

Example 6 To 9 parts by weight of the resin-coated carrier obtained in Production example 4 of coated carrier was mixed with 8 parts by weight of the encapsulated toner obtained in Production example 3 of encapsulated toner, and the mixture was mixed with V blender to about 8 parts.
The mixture was stirred for an hour to obtain a developer. When the above-mentioned developer was used and intermittently replenishing the capsule toner, copying was carried out by a commercially available OPC-equipped digital copier similar to that of Example 1 equipped with an agitator. No deterioration of the image was observed even after the operation, and a copy with good image quality was obtained.

Comparative Carrier Production Example 1 Fe ₂ O ₃ 55 mol%, ZnO 25 mol%, NiCO ₃
20 mol% is pulverized and mixed by a wet ball mill for 10 hours,
After drying, it was kept at 950 ° C. for 4 hours. This was ground by a wet ball mill for 24 hours to have a particle size of 10 μm or less. The slurry was granulated and dried, held at 1200 ° C. for 6 hours, pulverized and classified to 60 to 100 μm. The magnetic characteristics of this granulated ferrite carrier were measured to be 3000 Oe.
The value of magnetization at that time was 60 emu, and the coercive force and remanent magnetization were 0. Moreover, the apparent density was 2.9.

Comparative Carrier Production Example 2 Fe ₂ O ₃ was ground and mixed in a wet ball mill for 10 hours,
After drying, it was kept at 950 ° C. for 4 hours. This was ground by a wet ball mill for 24 hours to have a particle size of 10 μm or less. The slurry is granulated and dried, and then 120 times in a nitrogen atmosphere in an electric furnace.
After holding at 0 ℃ for 6 hours, crush and classify to 60-100
μm. When the magnetic properties of this granulated magnetite carrier were measured, the value of magnetization at 3000 Oe was 60 em.
u, the coercive force and the residual magnetization were 0. Moreover, the apparent density was 2.9.

Comparative Coated Carrier Production Example 1 Using the ferrite carrier obtained in Comparative Carrier Production Example 1, 10% by weight of the coating silicone resin composition was coated on the carrier using a fluidized bed, and further 1
Baking was performed at 50 ° C. for 3 hours to obtain a resin-coated carrier. The apparent density of the resin-coated carrier is 2.80.
g / cm ^3, the resistance is 2.5 × 10 ¹² Ωcm, and a saturation magnetization of 75 emu / g. Further, the thickness of the coating material of the coated carrier was 1.0 μm as a result of measuring the total coating material weight with a carbon analyzer.

Comparative Coated Carrier Production Example 2 Using the ferrite carrier obtained in Comparative Carrier Production Example 1, 15% by weight of the acrylic resin composition for coating was coated on the carrier using a fluidized bed, and further 1
Baking was performed at 50 ° C. for 3 hours to obtain a resin-coated carrier. The apparent density of the resin-coated carrier is 2.8 g.
/ Cm ³ , the resistance was 4 × 10 ¹² Ωcm, and the saturation magnetization was 75 emu / g. Further, the thickness of the coating material of the coated carrier was calculated to be 1.8 μm by calculating the total coating material weight with a carbon analyzer.

Comparative Coated Carrier Production Example 3 Using the magnetite carrier obtained in Comparative Carrier Production Example 2, 1% by weight of the acrylic resin composition for coating was coated on the carrier using a fluidized bed, and further 1
Baking was performed at 50 ° C. for 3 hours to obtain a resin-coated carrier. The apparent density of the resin-coated carrier is 2.8 g.
/ Cm ³ , the resistance was 2 × 10 ¹² Ωcm, and the saturation magnetization was 90 emu / g. Further, the thickness of the coating material of the coat carrier was calculated by measuring the total weight of the coating material with a carbon analyzer, and the result was 0.1 μm.

Comparative Example 1 92 parts by weight of the resin-coated carrier obtained in Comparative Coated Carrier Production Example 1 was mixed with 8 parts by weight of the encapsulated toner obtained in Capsule Toner Production Example 1 and mixed in a V blender for about 8 hours. A developer was obtained by stirring. When the above-mentioned developer was used and intermittently replenishing the capsule toner, copying was performed with a commercially available OPC-equipped digital copier equipped with a stirring device, and image deterioration was observed at 20,000 sheets of A4 size. An increase in density and a decrease in gradation were observed, and background fogging occurred and a black core was observed. Further, toner agglomeration occurred in the developer.

Comparative Example 2 92 parts by weight of the resin coated carrier obtained in Comparative Coated Carrier Production Example 2 was mixed with 8 parts by weight of the capsule toner obtained in Capsule Toner Production Example 2 and mixed in a V blender for about 8 hours. A developer was obtained by stirring. When using the above-mentioned developer and intermittently replenishing the capsule toner while copying with a commercially available OPC-equipped digital copier equipped with a stirrer, image deterioration was observed at 20,000 sheets of A4 size. An increase in density and a decrease in gradation were observed.

Comparative Example 3 92 parts by weight of the resin coated carrier obtained in Comparative Coated Carrier Production Example 3 was mixed with 8 parts by weight of the encapsulated toner obtained in Capsule Toner Production Example 2 and mixed in a V blender for about 8 hours. A developer was obtained by stirring. When the above-mentioned developer was used and intermittently replenishing the capsule toner, copying was performed with a commercially available OPC-equipped digital copier equipped with a stirrer, and image deterioration was observed after 10,000 sheets of A4 size. An increase in density and a decrease in gradation were observed.

[0104]

INDUSTRIAL APPLICABILITY By using a two-component developer containing a carrier having a predetermined apparent density and saturation magnetization in the present invention, development suitable for the capsule toner of the present invention can be carried out, and low energy fixing and development can be performed. The life of the agent can be extended.

Claims (8)

[Claims] 1. A method for developing a latent image on an image bearing member using a two-component developer comprising toner particles and a magnetic carrier, wherein the toner contains at least a thermoplastic resin and a colorant. Material and an outer shell provided so as to cover the surface of the core material, which is a capsule toner in which the main component of the outer shell is amorphous polyester, and the carrier has an apparent density of 2.7 g / cm ^3. A developing method comprising the following ferrite or magnetite carrier. 2. A method of developing a latent image on an image bearing member using a two-component developer comprising toner particles and a magnetic carrier, wherein the toner contains at least a thermoplastic resin and a colorant. Material and an outer shell provided so as to cover the surface of the core material, which is a capsule toner in which the main component of the outer shell is amorphous polyester, and the carrier has a saturation magnetization of 60 emu / g or less. A developing method characterized by being a carrier. 3. The glass transition point of the amorphous polyester is
The developing method according to claim 1 or 2, which has a temperature of 50 to 80 ° C. 4. The acid value of the amorphous polyester is 3 to 50.
The developing method according to claim 1, which is (KOHmg / g). 5. The amorphous polyester is obtained by polycondensation of at least one alcohol monomer and at least one carboxylic acid monomer, and is a polyhydric alcohol unit having a valence of at least three. 3. The developing method according to claim 1, which is obtained by polycondensation using a polymer and / or a monomer containing a polyvalent carboxylic acid monomer having a valence of 3 or more. 6. The encapsulated toner has a glass transition point of 10 derived from a thermoplastic resin which is a main component of a heat-fusible core material.
The developing method according to claim 1 or 2, wherein the temperature is from about 50 ° C. 7. The developing method according to claim 1, wherein the ferrite or magnetite carrier is coated with a resin. 8. The developing method according to claim 7, wherein the coating layer formed by the coating treatment has a thickness of 1.0 μm or more.