JPH05107931A - Developing method - Google Patents

Abstract

PURPOSE:To execute development suitable for thermal dissociation capsule toner and to obtain excellent printing quality and developer having long life by using jamping developing system. CONSTITUTION:The thermal dissociation capsule toner being magnetic toner containing magnetic powder is used in this developing method in which a photosensitive body 1 holding an electrostatic latent image on its surface and a non-magnetic sleeve 3 carrying the magnetic toner on its surface and having a magnet inside are faced so as to hold a gap equal to or above the thickness of a magnetic toner layer in a developing part, they are turned in the same direction, and electric field in the developing gap is alternated both in an image part and a non-image part, then development is performed while giving alternating electric field whose frequency is <=1kHz.

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 jumping developing method in the case where the toner is a thermal dissociation type capsule toner containing magnetic powder.

[0002]

2. Description of the Related Art When an image is formed in a copying machine or a laser beam printer,
Development system is an important part.
Materials have been found and studied. Among them, two-component developing methods and one-component developing methods are systematically used, and the magnetic brush method is mainly used for both.

The basis of a two-component developing system using a developer and a replenishing toner composed of a toner containing a magnetic carrier and a colorant was devised in 1952 (USP2618).
551), the invention of the magnetic brush development system in 1953 (U
SP278639) greatly contributes to faithful image reproducibility and downsizing of the developing device. However, the drawbacks of the two-component developing system are that the image quality is poorly maintained, the developer is deteriorated, the concentration of the developer needs to be adjusted, it is not suitable for further size reduction, and toner scattering easily occurs. Various problems have been pointed out. On the other hand, since the one-component developing method is carrierless, the developing device is designed more compact than the two-component developing method because the device for keeping the toner concentration constant and the stirring device for the developer are not required. it can.

A method using a conductive magnetic toner (10 ⁸ Ω · cm or less) was previously devised as a one-component developing method (USP 3909258), but corona transfer is difficult with this low resistance toner, and at present, it is difficult. 10 magnetic toners
High resistance toner of ¹⁵ Ω · cm or more is used. However, since there is no charging partner such as a carrier, obtaining stable charging is a major problem, and the following three types of methods are known as this method.

(1) A method of simultaneously charging at the time of development by utilizing an electric field of a latent image (USP4121931, JP-A-53-53)
31136, JP-A-50-92137 and JP-A-54-134640), and (2) A method of transferring charges inside a developing device (JP-A-53-47936, JP-A-53-47936). 59-33908 and JP-A-53-53
4549) and (3) a method in which the toner layer is thinned on the sleeve and charged (Japanese Patent Laid-Open No. 50-45639).

Among these, (3) a method of thinning and charging the toner layer on the sleeve is a jumping method (JP-A-41-9475, USP3866574, USP).
P3890929) and FEED method (Japanese Patent Laid-Open No. 58-2).
No. 11712). Among them, in the jumping method, the toner layer and the electrostatic image holding surface are not in contact,
It develops with a gap and AC is used for the developing bias, and the magnetic toner on the magnetic brush flies and develops by the alternating electric field, so the background fog can be prevented and the application condition (voltage, frequency) of the alternating electric field It is known as a preferable developing method because it can obtain an optimum image (line drawing, gradation).

By the way, 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.
Further, in the fixing step, an image is formed by fixing with a fixing roller system which generally has high heat and high pressure. In such a conventional image forming method, the temperature of the heating element of the fixing device is very 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 2 kg /
Since fixing is performed with 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 time to reach the set temperature, and quick printing cannot be performed. Therefore, it is not suitable for a device such as a facsimile which requires quick printing. On the other hand, since it is not possible to expect the resin in the toner to be softened by heat in the conventional toner which is to be fixed at a fixing temperature of about 100 ° C. or less, fixing by plastic deformation of the resin is the main component, and usually a large amount of 5 kg / cm or more. 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 effectiveness of using a thermal dissociation type capsule toner as a toner is being evaluated. The thermal dissociation type encapsulated toner is a toner containing a shell having a property that the shell structure is weakened by heat and a core material that can be fixed by low linear pressure at low temperature (Japanese Patent Application No. 3-1).
4231). In this way, the thermal dissociative capsule toner is
Since the properties of the toner are significantly different from those of the conventional toner, development of a developing method suitable for using the toner is required.

[0011]

In order to solve the above-mentioned problems, the developing method of the present invention comprises a photoreceptor for holding an electrostatic latent image on the surface, a magnetic toner on the surface and a magnet inside. The non-magnetic sleeve has a non-magnetic sleeve in the developing section to hold a gap equal to or larger than the thickness of the magnetic toner layer, and causes the photosensitive member and the sleeve to rotate in the same direction. In the developing method in which an alternating electric field having a frequency of 1 KHz or less is applied so that the magnetic toner is alternating in both the case and the non-image area, the magnetic toner is a thermal dissociation type capsule toner containing magnetic powder. Here, in the toner, the main component of the capsule shell material is a resin having at least one bond of a heat dissociable urethane bond, a thiol urethane bond, or an s-thiourethane bond. Furthermore, in the heat dissociable urethane resin, which is the main component of this shell material, among the bonds involving all the isocyanate groups and / or isothiocyanate groups, the number of the bonds due to the reaction with the phenolic hydroxyl group and / or the thiol group is the number. Is 30% or more. The softening point of the capsule toner is 80 ° C. to 150 ° C.

The toner used in the present invention is a magnetic toner, which is a thermal dissociation type capsule toner containing magnetic powder.
The thermal dissociation type capsule 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 structure of the shell changes due to heat, and the core material is released and fixed when pressure is applied.

Such a capsule toner can usually be easily obtained by the following manufacturing method. (1) A spray drying method (spray drying method) in which the core substance is dispersed in a non-polymer aqueous solution or a polymer emulsion and then the dispersion is spray-dried, and (2) around the core substance from a mixed aqueous solution of an ionic polymer colloid. Phase separation method (coacervation method) in which micro-capsules are formed from simple emulsion through complex emulsion by causing phase separation in
(3) The core material solution or dispersion is dispersed in a W / O or O / W type emulsion system, and at the same time, the shell material monomer (A) is collected at the interface, and in the next step, the monomer (B) and the monomer at the interface are collected. In addition to the interfacial polymerization method in which (A) reacts, an in situ polymerization method, a liquid hardening coating method, an air suspension coating method, an electrostatic coalescence method, a vacuum vapor deposition coating method and the like can be mentioned. In the present invention, the capsule toner produced by the interfacial polymerization method or the spray drying method is preferably used. In the interfacial polymerization method, not only the functional separation of the core material and the shell material is easy, but also a uniform toner can be produced in an aqueous system, and a substance having a low softening point can be used for the core material. A toner having desirable properties can be obtained.

As the shell material, a styrene resin (Japanese Patent Laid-Open No.
-80407), a polyamide resin (JP-A-58)
-66948), an epoxy resin (JP-A-59-59).
No. 148066), a polyurethane resin (Japanese Patent Laid-Open No. Sho 5)
No. 7-179860), polyurea-based resins (JP-A No. 62-150262), and many others have been devised. Examples of the heat-pressure fixing substance contained in the core material include thermoplastic resins having a glass transition point (Tg) of 10 ° C. or higher and 50 ° C. or lower, such as polyester resin, polyamide resin, polyester polyamide resin, and vinyl resin. ..

With respect to the thermal characteristics of the core material, the structure and thermal characteristics of the shell material are significantly involved in the fixability of the toner as a whole. Since it has both storage stability and low-temperature fixability, it is a very preferable material in the image forming method of the present invention. The main component of such a shell material is a resin having at least one bond of thermal dissociative urethane bond, thiol urethane bond, or s-thiourethane bond. Furthermore, in the heat dissociable urethane resin, which is the main component of this shell material, among the bonds involving all the isocyanate groups and / or isothiocyanate groups, the number of the bonds due to the reaction with the phenolic hydroxyl group and / or the thiol group is the number. Is 30% or more. For example, an isocyanate compound and / or an isothiocyanate compound and a phenolic hydroxyl group and / or
Alternatively, a resin obtained by a reaction with a compound having a thiol group or the like is preferably used (Japanese Patent Application No. 14231/1991).
issue).

More specifically, the toner used in the present invention is a capsule toner composed of a heat-fusible core material containing at least a magnetic powder as a colorant, and an outer shell provided so as to cover the surface of the core material. The main component of the outer shell is (1) a monovalent isocyanate compound and / or an isothiocyanate compound in an amount of 0 to 30 mol% of the whole isocyanate compound and / or isothiocyanate compound, Isocyanate compound and / or isothiocyanate compound in 100 to 70 mol% of the whole isocyanate compound and / or isothiocyanate compound
And (3) 0 to 30 mol% of the whole compound that reacts with an isocyanate group and / or an isothiocyanate group having one active hydrogen that reacts with an isocyanate group and / or an isothiocyanate group, and (4) an isocyanate group and And / or a compound having two or more active hydrogens that react with an isothiocyanate group in 100 to 70 mol% of the whole compound that reacts with an isocyanate group and / or an isothiocyanate group, and (1) + (2) (3) + (4) to the number of moles of the resin made to react in the range of 1: 1 to 1:20, in which the total isocyanate groups and / or isothiocyanate groups are involved Capsule toners in which at least 30% or more in the number are bonds exhibiting thermal dissociation property are listed.

The bond exhibiting thermal dissociation is preferably a bond derived from the reaction of a phenolic hydroxyl group and / or a thiol group with an isocyanate group and / or an isothiocyanate group. Specifically, the monovalent isocyanate compound of (1) above includes ethyl isocyanate, octyl isocyanate, 2-chloroethyl isocyanate, chlorosulfonyl isocyanate, cyclohexyl isocyanate, n-dodecyl isocyanate, and butyl isocyanate. , N-hexyl isocyanate, lauryl isocyanate, phenyl isocyanate, m-chlorophenyl isocyanate, 4-chlorophenyl isocyanate, p-cyanophenyl isocyanate, 3,4-dichlorophenyl isocyanate, o-tolyl isocyanate, isocyanic acid m-tolyl, p-tolyl isocyanate, p-isocyanate
-Toluenesulfonyl, 1-naphthyl isocyanate, o-nitrophenyl isocyanate, m-nitrophenyl isocyanate, p-nitrophenyl isocyanate, phenyl isocyanate, p-bromophenyl isocyanate, o-methoxyphenyl isocyanate, isocyanate Acid m-methoxyphenyl, p-methoxyphenyl isocyanate,
Examples thereof include monovalent isocyanate compounds such as ethyl isocyanato acetate, butyl isocyanato acetate, and trichloroacetyl isocyanate.

Examples of the divalent or higher valent isocyanate compound (2) include, for example, 2,4-tolylene diisocyanate, a dimer of 2,4-tolylene diisocyanate and 2,6-
Tolylene diisocyanate, p-xylylene diisocyanate, m-xylylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 1,5-naphthylene diisocyanate, 3,3'-dimethyl-diphenyl-4,4'-diisocyanate, 3, 3'-Dimethyl-diphenylmethane-
Aromatic isocyanate compounds such as 4,4'-diisocyanate, metaphenylene diisocyanate, triphenylmethane-triisocyanate, polymethylenephenyl isocyanate, etc., Aliphatic compounds such as hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, lysine diisocyanate, dimer acid diisocyanate, etc. Alicyclic isocyanate compounds such as isocyanate compounds, isophorone diisocyanate, 4,4'-methylenebis (cyclohexyl isocyanate), methylcyclohexane-2,4 (or 2,6) diisocyanate, 1,3- (isocyanatomethyl) cyclohexane Examples thereof include isocyanate compounds such as an adduct of 3 mol of diisocyanate and 1 mol of trimethylolpropane. Examples of the compound having an isothiocyanate group include compounds such as phenyl isothiocyanate, xylylene-1,4-diisothiocyanate, and ethylidyne diisothiocyanate. Among them, a compound in which an isocyanate group is directly bonded to an aromatic ring is preferably used because it has an effect of lowering the thermal dissociation temperature after the urethane bond is formed.

The monovalent isocyanate compound and / or isothiocyanate compound (1) described above can be used up to 30 mol% of the whole isocyanate compound and / or isothiocyanate compound also for adjusting the molecular weight of the outer shell resin. If it exceeds mol%, the storage stability of the capsule toner deteriorates, which is not preferable.

As the compound having one active hydrogen which reacts with the isocyanate group and / or the isothiocyanate group of the above (3), methyl alcohol, ethyl alcohol,
Aliphatic alcohols such as propyl alcohol, isopropyl alcohol, butyl alcohol, isobutyl alcohol, t-butyl alcohol, pentyl alcohol, hexyl alcohol, cyclohexyl alcohol, heptyl alcohol, octyl alcohol, nonyl alcohol, decyl alcohol, lauryl alcohol, stearyl alcohol, phenol , O-cresol, m-cresol, p-cresol, 4-butylphenol, 2-sec
-Butylphenol, 2-tert-butylphenol, 3
-Tert-butylphenol, 4-tert-butylphenol, nonylphenol, isononylphenol, 2-propenylphenol, 3-propenylphenol, 4-
Propenylphenol, 2-methoxyphenol, 3-
Methoxyphenol, 4-methoxyphenol, 3-acetylphenol, 3-carbomethoxyphenol, 2
-Chlorophenol, 3-chlorophenol, 4-chlorophenol, 2-bromophenol, 3-bromophenol, 4-bromophenol, benzyl alcohol,
1-naphthol, 2-naphthol, 2-acetyl-1-
Examples thereof include compounds such as aromatic alcohols such as naphthol and amides such as ε-caprolactam.

Among them, the phenol derivative represented by the following formula (I) is preferably used.

[Chemical 1] (In the formula, R ₁ , R ₂ , R ₃ , R ₄ , and R ₅ are independently H, or an alkyl group having 1 to 9 carbon atoms, an alkenyl group, an alkoxy group, an alkanoyl group, a carboalkoxy group, or an aryl group. Or halogen.)

Among the compounds having two or more active hydrogens which react with the isocyanate group and / or the isothiocyanate group of the above (4), as the divalent or higher valent alcohol compound,
For example, catechol, resorcin, hydroquinone, 4-
Methylcatechol, 4-t-butylcatechol, 4-acetylcatechol, 3-methoxycatechol, 4-phenylcatechol, 4-methylresorcin, 4-ethylresorcin, 4-t-butylresorcin, 4-hexylresorcin, 4-chloro Resorcin, 4-benzylresorcin, 4-acetylresorcin, 4-carbomethoxyresorcin, 2-methylresorcin, 5-methylresorcin, t-butylhydroquinone, 2,5-di-t-butylhydroquinone, 2,5-di- t-amylhydroquinone, tetramethylhydroquinone, tetrachlorohydroquinone, methylcarboaminohydroquinone, methylureidohydroquinone, benzonorbornene-3,6-
Diol, bisphenol A, bisphenol S, 3,3 '
-Dichlorobisphenol S, 2,2'-dihydroxybenzophenone, 2,4-dihydroxybenzophenone, 4,4 '
-Dihydroxybenzophenone, 2,2'-dihydroxydiphenyl, 4,4'-dihydroxydiphenyl, 2,2'-dihydroxydiphenylmethane, 3,4-bis (p-hydroxyphenyl) hexane, 1,4-bis (2- ( p-hydroxyphenyl) propyl) benzene, bis (4-hydroxyphenyl) methylamine, 1,3-dihydroxynaphthalene, 1,4-dihydroxynaphthalene, 1,5-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, 1,
5-dihydroxyanthraquinone, 2-hydroxybenzyl alcohol, 4-hydroxybenzyl alcohol,
2-hydroxy-3,5-di-t-butylbenzyl alcohol, 4-hydroxy-3,5-di-t-butylbenzyl alcohol, 4-hydroxyphenethyl alcohol, 2
-Hydroxyethyl-4-hydroxybenzoate, 2
-Hydroxyethyl-4-hydroxyphenyl acetate, resorcin mono-2-hydroxyethyl ether,
Hydroxyhydroquinone, gallic acid, ethyl 3,4,5-trihydroxybenzoate and the like can be mentioned. Among them, a catechol derivative represented by the following formula (II) or a resorcin derivative represented by the following formula (III) is preferably used.

[0023]

[Chemical 2] (In the formula, R ₆ , R ₇ , R ₈ , and R ₉ independently represent H, or an alkyl group having 1 to 6 carbon atoms, an alkenyl group, an alkoxy group, an alkanoyl group, a carboalkoxy group, an aryl group, or halogen. Show.)

[Chemical 3] (In the formula, R ₁₀ , R ₁₁ , R ₁₂ , and R ₁₃ independently represent H, or an alkyl group having 1 to 6 carbon atoms, an alkenyl group, an alkoxy group, an alkanoyl group, a carboalkoxy group, an aryl group, or halogen. Show.)

Other compounds having at least one functional group other than a hydroxyl group which reacts with an isocyanate group and / or an isothiocyanate group and having at least one phenolic hydroxyl group include, for example,
o-hydroxybenzoic acid, m-hydroxybenzoic acid, p
-Hydroxybenzoic acid, 5-bromo-2-hydroxybenzoic acid, 3-chloro-4-hydroxybenzoic acid, 4-chloro-2-hydroxybenzoic acid, 5-chloro-2-hydroxybenzoic acid, 3,5-dichloro -4-Hydroxybenzoic acid, 3-methyl-2-hydroxybenzoic acid, 5-methoxy-2-hydroxybenzoic acid, 3,5-di-t-butyl-4-hydroxybenzoic acid, 4-amino-2-hydroxy Benzoic acid, 5-amino-2-hydroxybenzoic acid, 2,
5-dinitrosalicylic acid, sulfosalicylic acid, 4-hydroxy-3-methoxyphenylacetic acid, catechol-4-
Carboxylic acid, 2,4-dihydroxybenzoic acid, 2,5-dihydroxybenzoic acid, 2,6-dihydroxybenzoic acid, 3,4
-Dihydroxybenzoic acid, 3,5-dihydroxybenzoic acid, 3,4-dihydroxyphenylacetic acid, m-hydroxycinnamic acid, p-hydroxycinnamic acid, 2-amino-4-methylphenol, 2-amino-5-methylphenol 5,
-Amino-2-methylphenol, 3-amino-2-naphthol, 8-amino-2-naphthol, 1-amino-
2-naphthol-4-sulfonic acid, 2-amino-5-naphthol-4-sulfonic acid, 2-amino-4-nitrophenol, 4-amino-2-nitrophenol, 4-amino-2,6-dichlorophenol , O-aminophenol, m-aminophenol, p-aminophenol, 4
-Chloro-2-aminophenol, 1-amino-4-hydroxyanthraquinone, 5-chloro-2-hydroxyaniline, α-cyano-3-hydroxycinnamic acid, α-cyano-4-hydroxycinnamic acid, 1-hydroxynaphthoene Acid, 2-hydroxynaphthoic acid, 3-hydroxynaphthoic acid, 4-hydroxyphthalic acid and the like can be mentioned.

The polythiol compounds having one or more thiol groups in one molecule include ethanethiol, 1
-Propanethiol, 2-propanethiol, thiophenol, bis (2-mercaptoethyl) ether, 1,2
-Ethanedithiol, 1,4-butanedithiol, bis (2-mercaptoethyl) sulfide, ethylene glycol bis (2-mercaptoacetate), ethylene glycol bis (3-mercaptopropionate), 2,2-
Dimethylpropanediol bis (2-mercaptoacetate), 2,2-dimethylpropanediol bis (3-mercaptopropionate), trimethylolpropane tris (2-mercaptoacetate), trimethylolpropane tris (3-mercaptopropionate) ), Trimethylolethanetris (2-mercaptoacetate), trimethylolethanetris (3-mercaptopropionate), pentaerythritol tetrakis (2
-Mercaptoacetate), pentaerythritol tetrakis (3-mercaptopropionate), dipentaerythritol hexakis (2-mercaptoacetate), dipentaerythritol hexakis (3-mercaptopropionate), 1,2-dimercaptobenzene ,
4-methyl-1,2-dimercaptobenzene, 3,6-dichloro-1,2-dimercaptobenzene, 3,4,5,6-tetrachloro-1,2-dimercaptobenzene, xylylenedithiol, 1 Examples include 3,3,5-tris (3-mercaptopropyl) isocyanurate.

In the thermally dissociable outer shell resin used in the present invention, the thermally dissociable bonds include all isocyanate groups and / or
Alternatively, among the bonds involving isothiocyanate groups, the number is at least 30% or more, preferably 50%. If the number of the bonds that undergo thermal dissociation is less than 30% of the number of bonds involving all isocyanate groups and / or isothiocyanate groups, the capsule shell strength will not be sufficiently reduced during heat and pressure fixing, leading to excellent fixing performance of the core material. I can't.

In the encapsulated toner of the present invention, of the bonds involving all the isocyanate groups and / or isothiocyanate groups, the number of bonds due to the reaction with phenolic hydroxyl groups and / or thiol groups is 30%.
Within the range of less than the phenolic hydroxyl group and /
Or a compound having a functional group which reacts with an isocyanate group other than a thiol group, for example, malonic acid esters, active methylene group-containing compounds such as acetoacetic acid esters, oximes such as methyl ethyl ketone oxime, carboxylic acids, polyols, polyamines, Aminocarboxylic acid, aminoalcohol and the like can be used as the shell forming substance.

The above active methylene group-containing compound includes
Malonic acid, monomethyl malonate, monoethyl malonate,
Active methylene groups such as isopropyl malonate, dimethyl malonate, diethyl malonate, diisopropyl malonate, tert-butyl ethyl malonate, diamide malonate, acetylacetone, methyl acetoacetate, ethyl acetoacetate, tert-butyl acetoacetate, allyl acetoacetate Examples of the compound include:

Examples of the carboxylic acid include monovalent carboxylic acids such as acetic acid, propionic acid, butyric acid, isobutyric acid, pentanoic acid, hexanoic acid and benzoic acid, maleic acid, fumaric acid,
Citraconic acid, itaconic acid, glutaconic acid, phthalic acid,
Isophthalic acid, terephthalic acid, succinic acid, adipic acid,
Divalent carboxylic acids such as sebacic acid, azelaic acid, malonic acid, n-todecenylsuccinic acid, isododecenylsuccinic acid, n-todecylsuccinic acid, isododecylsuccinic acid, n-octenylsuccinic acid, n-octylsuccinic acid, 1 , 2,
4-benzenetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 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,
Examples thereof include trivalent or higher carboxylic acids such as 1,2,7,8-octanetetracarboxylic acid, pyromellitic acid, and empol trimer acid.

Examples of the above-mentioned polyol include diols such as ethylene glycol, propylene glycol, butylene glycol, neopentyl glycol, hexamethylene glycol, diethylene glycol and dipropylene glycol, glycerin, trimethylolpropane,
Trimethylolethane, triols such as 1,2,6-hexanetriol, pentaerythritol, and water and the like, examples of the polyamine, ethylenediamine, hexamethylenediamine, diethylenetriamine, iminobispropylamine, phenylenediamine,
Examples include xylylenediamine and triethylenetetramine.

In the present invention, the compound (3) having one active hydrogen that reacts with the isocyanate group and / or isothiocyanate group is 30 mol% of the whole compound that reacts with the isocyanate group and / or isothiocyanate group.
However, if it exceeds 30 mol%, the storage stability of the capsule toner deteriorates, which is not preferable. Further, an isocyanate compound and / or an isothiocyanate compound [(1) + (2)] constituting the outer shell, an isocyanate group and / or
Or a compound that reacts with an isothiocyanate group [(3) +
The molar ratio of (4)] is preferably 1: 1 to 1:20 so that unreacted isocyanate groups do not remain.

In the production of the capsule toner, the outer shell is preferably formed by interfacial polymerization or in-situ polymerization. For example, the mother particles as the core substance and the number average particle size are 1% of the number average particle size of the mother particles. It may be carried out by a dry method in which the outer shell particles of / 8 or less and the child particles of the outer shell forming material are stirred at high speed in an air stream to form the outer shell.

The outer shell resin can be produced without a catalyst, but when a catalyst is used, a tin-based catalyst such as dibutyltin dilaurate, 1,4-diazabicyclo [2.2.2] octane, N, N,
Known urethane catalysts such as amine-based catalysts such as N-tris (dimethylaminopropyl) -hexahydro-S-triazine can be used.

The resin used as the core material of the encapsulated toner in the present invention has a glass transition point (Tg) of 10 ° C. or higher and 50 or higher.
Thermoplastic resins such as polyester resins, polyester / polyamide resins, polyamide resins and vinyl resins having a temperature of not higher than 0 ° C. are mentioned, and vinyl resins are particularly preferable.

Examples of the monomer constituting the vinyl resin include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-
Styrene or styrene derivatives such as ethylstyrene, 2,4-dimethylstyrene, p-chlorostyrene, vinylnaphthalene, etc., such as ethylene, propylene, butylene,
Ethylenically unsaturated monoolefins such as isobutylene and the like, vinyl esters such as vinyl chloride, vinyl bromide, vinyl fluoride, vinyl acetate, vinyl propionate, vinyl formate and vinyl caproate, for example acrylic acid,
Methyl acrylate, ethyl acrylate, acrylic acid n-
Propyl, 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, stearyl acrylate, methoxyethyl acrylate, 2-hydroxyethyl acrylate, acrylic acid Glycidyl, 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, decyl methacrylate, lauryl methacrylate, methacrylic acid Ethylenic monocarboxylic acids and their esters such as 2-ethylhexyl acid salt, stearyl methacrylate, methoxyethyl methacrylate, 2-hydroxyethyl methacrylate, glycidyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate and the like. , An ethylenic monocarboxylic acid substitution product such as acrylonitrile, methacrylonitrile, acrylamide, etc., an ethylenic dicarboxylic acid such as dimethyl maleate and the substitution product thereof, vinyl ketones such as vinyl methyl ketone, for example vinyl methyl ether Vinylidene halides such as vinylidene chloride and N-vinyl compounds such as N-vinylpyrrole and N-vinylpyrrolidone. is there. Preferably, of the components constituting the resin for the core material according to the present invention, styrene or a styrene derivative is preferably 50 to 90 parts by weight for forming the main skeleton of the resin, and ethylene is used for adjusting the thermal characteristics such as the softening temperature of the resin. The monocarboxylic acid and its ester are preferably used in an amount of 10 to 50 parts by weight.

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.

If a large amount of these cross-linking agents is used, the capsulated toner is less likely to be melted by heat, resulting in poor fixability. The amount of these crosslinking agents used is preferably 0.001 to 15% by weight (more preferably 0.1 to 10% by weight) based on the polymerizable monomer. 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 in producing the vinyl resin, 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 per Examples thereof include peroxide type polymerization initiators such as oxide, isopropyl peroxycarbonate, cumene hydroperoxide, 2,4-dichlorobenzoyl peroxide, lauroyl peroxide and dicumyl peroxide. Two or more kinds of polymerization initiators may be mixed and used for the purpose of controlling the molecular weight and molecular weight distribution of the polymer, the reaction time, or the like. 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.

If necessary, for the purpose of improving fixability and releasability at the time of fixing, for example, polyolefin, fatty acid metal salt, fatty acid ester, partially saponified fatty acid ester, higher fatty acid, higher alcohol may be contained in the core material. Any one or more additives such as paraffin wax, amide wax, polyhydric alcohol ester, silicon varnish, aliphatic fluorocarbon, and silicone oil may be contained.

The above-mentioned polyolefin is, for example, a resin such as polypropylene, polyethylene or polybutene, 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, micro wax, 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 or JP
Examples thereof include the fluorine-containing surfactant described in JP-A-53-124428. However, in the production of capsule toner, when an outer shell is formed by an interfacial polymerization method or an in-situ polymerization method, a compound having a functional group capable of reacting with an isocyanate group such as the higher fatty acid or higher alcohol is often used. It is not preferable because it inhibits outer shell formation. The ratio of these offset preventing agents to the resin in the core material is preferably 1 to 20% by weight.

If desired, a colorant can be added to the core material of the encapsulated toner, and all dyes, pigments and the like used in conventional colorants 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 Fast Scarlet, Pigment Green B, Rhodamine-B Base, Solvent Red 49, Solvent Red 146, Solvent Blue 35, etc., and mixtures thereof. About 1 to 15 parts by weight is used for 100 parts by weight of the resin in the material, which can improve the image density.

The toner in the present invention is a magnetic toner, and a thermal dissociation type capsule toner containing magnetic powder is used. That is, the magnetic particles added to the core material in order to adjust the charge amount, electric resistance, etc. in the heat dissociation type capsule toner include, for example, ferrite, magnetite and other iron, cobalt, nickel and other ferromagnetic materials. Metals or alloys shown, or compounds containing these elements, or alloys containing no ferromagnetic elements but exhibiting ferromagnetism by appropriate heat treatment, eg manganese-copper-aluminum, manganese-copper-tin, etc. Alloys of the type called Heusler alloys containing manganese and copper, or chromium dioxide, and the like.

The various properties required for such magnetic powder are (1) maximum magnetizing force (σs) of 40 emu / g or more, and (2) holding force (H) of 50 to 500 Oe.
c), (3) specific electric resistance of 10 ² to 10 ⁷ Ω · cm, (4) practically sufficient blackness, (5) good moisture resistance,
(6) Good dispersibility with a binder resin is known. In many cases, an indeterminate magnetite, which is called iron black or iron ferrite and is often used as a pigment, is usually used as a magnetic toner, which satisfies the above requirements. On the other hand, the magnetic powder used in the magnetic capsule toner according to the present invention is preferably a cubic or rounded indefinite system, or more preferably a spherical magnetic powder, rather than an acicular system or indefinite system magnetic powder. The magnetic properties of the magnetic powder used in the present invention are 300 Oe.
Below, those having a coercive force (Hc) of 150 Oe or less and a maximum magnetizing force (σs) of 60 emu / g or more are preferable. These magnetic materials are uniformly dispersed in the core material in the form of fine powder having an average particle size of 0.1 to 1 μm. The content is 5 to 70 parts by weight, preferably 10 to 60 parts by weight, per 100 parts by weight of the encapsulated toner.

In order to contain the magnetic fine powder in order to obtain such a magnetic capsule toner, since the affinity for the core material and the organic substance such as the monomer is low as it is, the magnetic fine powder is used. When used together with a so-called coupling agent such as a titanium coupling agent, a silane coupling agent, and lecithin, or after being treated with the coupling agent, the magnetic fine powder can be uniformly dispersed.

An interfacial polymerization method or in
-In the case of manufacturing by the in situ polymerization method, the outer shell constituent material and the core material constituent material are dispersed in a dispersion medium, but a dispersion stabilizer is contained in the dispersion medium in order to prevent aggregation and coalescence of dispersoids. There is a need.

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. , Sodium pentadecyl sulfate, sodium octyl sulfate, sodium allyl-alkyl-polyether sulfonate, sodium oleate, sodium laurate, sodium caprate, sodium caprylate, sodium caproate, potassium stearate, calcium oleate, 3,3 -Disulfone diphenylurea-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 present invention, it is preferable that the main component of the heat-fusible core material in the capsule toner is a thermoplastic resin, and the glass transition point derived from the resin is 10 ° C. or higher and 50 ° C. or lower. If the point is lower than 10 ° C, the storage stability of the capsule toner is deteriorated, and if it exceeds 50 ° C, the fixing strength of the capsule toner is deteriorated, which is not preferable. In the present invention,
What is the glass transition point? When measured with a differential scanning calorimeter (manufactured by Seiko Denshi Kogyo Co., Ltd.) at a heating rate of 10 ° C / min, the extension of the baseline below the glass transition point and the peak from the rising part of the peak It is the temperature at the intersection with the tangent line showing the maximum slope up to the apex.

In the present invention, the softening point of the capsule toner is preferably 60 ° C. or higher and 130 ° C. or lower, but if it is lower than 60 ° C., the blocking resistance deteriorates, and if it exceeds 130 ° C., the fixing property deteriorates. Not preferable. In the present invention, the softening point is a high-performance flow tester (manufactured by Shimadzu Corporation).
While heating a 1 cm ³ sample at a heating rate of 6 ° C / min, a load of 20 kg / cm ² is applied by a plunger to push out a nozzle with a diameter of 1 mm and a length of 1 mm. Plunger drop (flow value)
-When a temperature curve is drawn and the height of the S-shaped curve is h, h
A temperature corresponding to / 2.

The particle size of the capsule toner of 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, the blocking resistance is deteriorated, and if it exceeds 1 μm, the heat melting property of the toner is deteriorated, which is not preferable.

If necessary, a fluidity improver or the like can be used in the capsule toner of the present invention. As the fluidity improver, for example, silica, alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide,
Quartz sand, clay, mica, wollastonite, diatomaceous earth, chromium oxide, cerium oxide, red iron oxide, antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silicon carbide, silicon nitride, etc. You can Fine silica powder is particularly preferable.

The fine silica powder is a fine powder having a Si--O--Si bond and may be produced by a dry method or a wet method. In addition to anhydrous silicon dioxide, any of aluminum silicate, sodium silicate, potassium silicate, magnesium silicate, zinc silicate, and the like may be used, 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.

The developing method of the present invention is a jumping developing method using the thermal dissociative capsule toner containing the magnetic powder as described above, and can be developed using a known jumping developing device. The basic structure of the developing device is, for example, as shown in FIG. 1, a fixed magnet roller 2, a non-magnetic sleeve 3 containing the fixed magnet roller 2, a coated magnetic blade 4, a toner hopper 5 and a stirring rod 6.

In the developing system of the present invention, it is necessary to make the toner layer thin. For this purpose, the magnetic blade 4 is opposed to the magnetic pole of the fixed magnet roller 2 to form a magnetic curtain, and the toner is formed. Is triboelectrically charged by friction with the sleeve, and the toner adhering to the sleeve is conveyed by the attraction force and magnetic force with the mirror image charge generated in the sleeve to obtain a thin layer. That is, in this case, the magnetic flux density is concentrated on the blade near the magnetic blade 4, and the magnetic attraction force is directed to the blade, but when the toner passes through the blade,
The concentration of the magnetic flux density on the blade is weakened, the toner is divided into two parts, the part near the blade is fixed to the blade, and the part near the sleeve is attracted to the sleeve by the attraction force and magnetic force with the image charge and separated from the blade. Go In this way, a thin layer of magnetic toner of 50 μm is obtained with a regulation gap of 240 μm, for example.

When the thin layer of the magnetic toner carried on the non-magnetic sleeve 3 in this way reaches the developing portion by the rotation of the sleeve, the developing magnetic field forms a minute brush to increase the thickness to about 100 μm. It becomes a thin layer. Since the gap between the surface of the photoconductor and the non-magnetic sleeve is about 300 μm, the gap greater than the thickness of the magnetic toner layer is held in the developing section. Then, by rotating both the photoconductor 1 and the non-magnetic sleeve 3 in the same direction, when the toner layer comes closest to the electrostatic latent image surface, the toner flies through this gap and the electrostatic latent image surface. Transfer to.

In this case, since the distance between the photoconductor and the non-magnetic sleeve is wider than that of the toner layer as described above, and because the AC bias is applied during development, the toner flies back and forth through the gap, but finally. A uniform toner layer is formed in the image area having a potential, and the boundary between the image area and the non-image area is accurately distinguished, and the background fog in the non-image area can be significantly reduced. In this case, since the AC component is applied, the γ value can be lowered and the gradation can be increased, but the γ value can be lowered as the intensity of the AC component is increased or the frequency is lowered. In the present invention, the electric field in the developing gap thus alternates in both the image portion and the non-image portion,
It is performed while applying an alternating electric field having a normal frequency of 1 KHz or less.

In such a jumping developing method, since no carrier is used, it is difficult for the toner to be overloaded.
In addition, because it is a thin layer that is charged only by frictional charging between the blade and toner and no load is applied between the photoconductor and the toner layer, an excessive load is not applied to the capsule toner. This is a preferable developing method for the thermal dissociation type capsule toner of the present invention in which abrasion due to friction must be avoided. In particular, in this developing method, since the photoreceptor layer and the toner layer on the non-magnetic sleeve surface are not in contact with each other, the pressure is not applied to the toner and the risk of damage to the outer shell of the capsule toner can be greatly reduced. , The life of the developer can be greatly extended.

When the developing method of the present invention is carried out, a normal developing system in which toner having a polarity opposite to that of the latent image on the photoconductor is developed by Coulomb force, and a bias voltage is applied to toner having the same polarity as the latent image on the photoconductor. Then, the latent image on the photoconductor can be developed by a reversal development method in which Coulomb repulsive force is used for development. 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.

[0059]

EXAMPLES The present invention will be described in more detail with reference to production examples and examples, but the present invention is not limited to these examples. Production Example 1 of magnetic toner Styrene 65.0 parts by weight, 2-ethylhexyl acrylate
To 35.0 parts by weight, magnetite "EPT1001" (manufactured by Toda Kogyo Co., Ltd.) 25 parts by weight, 2,2'-azobisisobutyronitrile 4.0 parts by weight, 4,4'-diphenylmethane diisocyanate "Millionate MT" (Nippon Polyurethane Industry Co., Ltd.) 9.5 parts by weight was added, and the mixture was put into an attritor (manufactured by Mitsui Miike Kakoki Co., Ltd.) and dispersed at 10 ° C. for 5 hours to obtain a polymerizable composition. This was added in an amount of 40% by weight to 800 g of an aqueous colloidal solution containing 4% by weight of tricalcium phosphate prepared in advance in a glass separable flask having a capacity of 2 liters, and TK homomixer (made by Tokushu Kika Kogyo Co., Ltd. ) With 5
The emulsion was emulsified and dispersed at a rotation speed of 10,000 rpm for 2 minutes at ℃. A four-neck glass lid was attached, a reflux type cooling tube, a thermometer, a dropping funnel with a nitrogen introducing tube, and a stainless steel stirring rod were attached, and the glass was placed in an electric heating mantle. A mixed solution of 15.2 g of 4-acetylcatechol, 0.7 g of dibutyltin dilaurate, and 40 g of ion-exchanged water was prepared and added dropwise from a dropping funnel over 30 minutes while stirring. Then, while continuing stirring under nitrogen, the temperature was raised to 80 ° C. and the reaction was carried out for 10 hours. After cooling, dissolve the dispersant in a 10% aqueous hydrochloric acid solution, filter, wash with water, and then at 45 ° C for 12 hours, 20 mm.
Dry under reduced pressure with Hg, classify with an air classifier, average particle size 1
An encapsulated toner having a 5.0 μm outer shell made of a heat dissociable polyurethane resin 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 Aerosil Co., Ltd.) was added and mixed to obtain a capsule toner of the present invention. The glass transition point derived from the resin in the core material was 30.2 ° C, and the softening point of the capsule toner was 90.0 ° C.

Manufacturing Example 2 of Magnetic Toner In Manufacturing Example 1, 25 parts by weight of magnetite "EPT1001" (manufactured by Toda Kogyo Co., Ltd.) has a holding power (Hc) of 63 Oe.
Substituting for 25 parts by weight of spherical magnetite having a maximum magnetizing force (σs) of 81 emu / g, the surface treatment was performed in the same manner as in Production Example 1 to obtain a capsule toner. The glass transition point derived from the resin in the core material was 30.2 ° C, and the softening point of the capsule toner was 90.0 ° C.

Example 1 Copy using the magnetic toner obtained in Production Example 1 and having a developing device shown in FIG. 1 equipped with a commercially available OPC (organic photoconductor) while intermittently replenishing the magnetic toner. When copying was performed with a machine (NP3825, manufactured by Canon Inc.), even if A4 size was developed and 100,000 sheets were developed, no deterioration of the image was observed and good quality image was obtained.

Example 2 Using the magnetic toner obtained in Production Example 2, a test was carried out in the same manner as in Example 1. As a result, even if an A4 size sheet was similarly developed and 150,000 sheets were developed, no image was obtained. No deterioration was observed and good quality image was obtained.

[0063]

By using the jumping development method in the present invention, development suitable for the heat dissociative capsule toner in the present invention can be carried out, and a developer having good printing quality and long life can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic view of a developing device used in the present invention.

[Explanation of symbols]

 1 photoconductor 2 fixed magnet roller 3 non-magnetic sleeve 4 magnetic blade 5 hopper 6 stirring rod 7 AC current

Claims (4)

[Claims] 1. A photoreceptor for holding an electrostatic latent image on a surface,
A non-magnetic sleeve carrying magnetic toner on its surface and having a magnet inside is made to stand by while maintaining a gap of at least the thickness of the magnetic toner layer in the developing section, and the photoreceptor and the sleeve are in the same direction. In the developing method in which the magnetic toner contains magnetic powder, the magnetic toner contains magnetic powder in a developing method in which the electric field in the developing gap is alternately rotated in both the image portion and the non-image portion so that the magnetic toner contains magnetic powder. A developing method characterized by being a toner. 2. The toner according to claim 1, wherein the main component of the shell material of the capsule is a resin having at least one bond of a heat dissociable urethane bond, a thiol urethane bond, or an s-thiourethane bond. Claim 1
The developing method described. 3. The heat dissociable urethane resin, which is the main component of the shell material according to claim 2, has a phenolic hydroxyl group and / or a thiol group among bonds involving all isocyanate groups and / or isothiocyanate groups. The developing method according to claim 2, wherein the number of bonds by the reaction with is 30% or more. 4. The developing method according to claim 1, wherein the capsule toner according to claim 1 has a softening point of 80 ° C. to 150 ° C.