JPH0545921A - Image forming method - Google Patents

Abstract

(57) [Summary] (Correction) [Structure] Application step 1 for forming an electrostatic latent image on an insulator,
In the image forming method, which includes a developing step 3 for forming the toner image by attaching the toner 9 to the obtained electrostatic latent image and a fixing step for fixing the formed toner image on the recording medium 6, a predetermined thermal characteristic is obtained. An endless film belt 7 is used as the insulator, and the toner thereon is preheated 4 and then pressure-fixed 5a and 5b. [Effect] By fixing the fixing temperature to a very low and low linear pressure by preheating the toner before fixing, troubles such as paper curling and jamming do not occur easily, and it takes time to reach the set temperature. Quick printing can be done without scratching. Further, since the transfer and the fixing are performed at the same time and the linear pressure is low, the scattering of the toner, the collapse of the fine lines, the blurring of the image are reduced and the image quality is improved, and the life of the fixing roller is extended.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming method used in plain paper copying machines, laser printers, plain paper facsimiles and the like.

[0002]

2. Description of the Related Art Conventionally, when an image is formed in a copying machine, a laser beam printer or the like, various methods such as electrostatic recording and electrophotography have been generally used. In the electrostatic recording method, a signal voltage is applied from a recording needle to an electrostatic recording sheet such as recording paper to form an electrostatic latent image, and then the electrostatic latent image is developed using a developing device such as a magnetic brush. Transfer and fixing by means of heat, pressure, etc. 3
It is a system consisting of two processes. However, in the conventional electrostatic recording method, toner adheres to an extra portion on a recording medium such as recording paper during development, so-called background stain occurs, and when voltage is directly applied to the recording paper by a recording needle. A problem that a normal image cannot be obtained due to foreign matter such as paper dust adhering to the recording needle is apt to occur, and there is a problem in obtaining a stable and high-quality image continuously.

As a means for improving such problems,
JP-A-55-84696 or JP-A-3-1370
As described in Japanese Patent Laid-Open No. No. 1-68242, a magnetic film or an insulating film is used, toner is evenly applied to the film surface, and then a thermal pulse is supplied from the back surface of the film by a thermal head in accordance with a signal to obtain the toner. There is known a method of fusing a sheet of paper and forming an image on the surface of the recording paper which faces the sheet.
However, in this method, the toner cannot be applied uniformly, and the image becomes uneven in stripes, and there is a concern that a part of the applied toner layer may agglomerate due to heat. There is a high possibility that it will behave as a foreign substance. Further, it has been pointed out that there is a problem that toner adheres to an extra portion on a recording medium such as a recording paper at the time of fixing, so-called scumming is likely to occur.

As described above, various problems have been pointed out in the conventional electrostatic recording method, and from these viewpoints, the development of a new image forming method and a toner adapted thereto are expected, but they are still satisfactory. The reality is that we have not obtained what we can do. An object of the present invention is to provide a novel image forming method which solves the above various problems.

[0005]

In order to solve the above-mentioned problems, the image forming method of the present invention comprises an applying step of forming an electrostatic latent image on an insulator and a toner on the obtained electrostatic latent image. In the image forming method, which comprises a developing process for forming a toner image by adhering the toner and a fixing process for fixing the formed toner image on a recording medium, a heat-meltable core material containing the toner and at least a colorant, A capsule toner comprising an outer shell provided so as to cover the surface of a core material, wherein the main component of the outer shell is (1) a monovalent isocyanate compound and / or an isothiocyanate compound. Or 0 for all isothiocyanate compounds
˜30 mol%, (2) Divalent or higher valent isocyanate compound and / or isothiocyanate compound is 100 to 70 of the whole isocyanate compound and / or isothiocyanate compound.
Mol%, and (3) 0 to 30 mol% of the whole compound that reacts with a compound having one active hydrogen that reacts with an isocyanate group and / or an isothiocyanate group with an isocyanate group and / or an isothiocyanate group, (4) an isocyanate A compound having two or more active hydrogens that react with a group and / or an isothiocyanate group, out of 100 to 70 mol% of the whole compound that reacts with an isocyanate group and / or an isothiocyanate group, (1) + (2) A bond comprising a resin obtained by reacting in the range of 1: 1 to 1:20 in the ratio of the number to the number of moles of (3) + (4), in which all isocyanate groups and / or isothiocyanate groups are involved. Among them, at least 30% or more in the number is a capsule toner having a bond exhibiting thermal dissociation property, the insulator is an endless film belt, and the endless film After preheating the toner on the belt consists of wearing pressure fixing. The preheating temperature of the toner on the endless film belt is 40 to 120 ° C.
And the linear pressure in the fixing process is 0.5 to 4 kg / cm.
Consists of being.

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, dimers 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 entire isocyanate compound and / or isothiocyanate compound also for controlling 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 in 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.

Of these, a 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), the divalent or higher valent alcohol compound is
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, the catechol derivative represented by the following formula (II) or the resorcin derivative represented by the following formula (III) is preferably used.

[0012]

[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.

Further, 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 heat dissociable outer shell resin used in the present invention, the heat 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%. When the number of the bonds that thermally dissociate is less than 30% of the number of bonds involving all isocyanate groups and / or isothiocyanate groups, the capsule outer shell strength is not sufficiently reduced during heat and pressure fixing, and the excellent fixing performance of the core material is brought out. I can't cut it.

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.

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 diameter are 1% of the number average particle diameter 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 resin for the outer shell 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 capsule 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. Glass transition point
If the temperature is less than 10 ° C, the storage stability of the capsule toner deteriorates, and
If the temperature exceeds ℃, the fixing strength of the capsule toner deteriorates, which is not 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 cross-linking agent is added to the monomer composition constituting the resin for the core material according to the present invention, known cross-linking agents can be appropriately used (combined with two or more kinds if necessary). .. When the amount of these cross-linking agents used is large, the toner is less likely to be melted by heat, resulting in poor heat fixing property or heat pressure fixing property. Further, when the amount used is small, 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 thermal pressure fixing. Further, 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. If necessary, the core material may contain one or more known anti-offset agents for the purpose of improving offset resistance in heat and pressure fixing. The ratio of these offset preventing agents to the resin in the core material is preferably 1 to 20% by weight.

Although the colorant is contained in the core material of the capsule toner of the present invention, all the dyes, pigments and the like used in the conventional colorant for toner can be used. Usually, about 1 to 15 parts by weight is used with respect to 100 parts by weight of the resin in the core material.

In the outer shell material of the capsule toner of the present invention, as a charge control agent, a metal-containing dye such as a metal complex of an organic compound having a carboxyl group or a nitrogen group conventionally used in toner, nigrosine, etc. May be added in an appropriate amount. Further, the charge control agent may be mixed with the toner and used.

If desired, a fluidity improver, a cleaning improver, etc. can be used in the capsule toner of the present invention. Further, an additive for adjusting the developability, for example, fine particle powder of a polymer of methacrylic acid methyl ester may be used. Further, a small amount of carbon black may be used for toning and resistance adjustment. The softening point of the capsule toner in the present invention is preferably 80 ° C. or higher and 150 ° C. or lower, but if it is lower than 80 ° C., the offset resistance deteriorates, and if it exceeds 150 ° C., the fixing strength deteriorates, which is not preferable. The particle size of the capsule toner in the present invention is not particularly limited, but the average particle size is usually 3 to.
It is set to 30 μm. The thickness of the outer shell of the capsule toner is 0.01 ~
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.

[0026]

According to the present invention, the heat dissociation type capsule toner forming the toner image formed on the insulative endless film belt is pre-heated and then pressure-fixed by the fixing roller (pressure roller). Thus, by preheating the toner before fixing, the fixing temperature can be set extremely low and low linear pressure. Since the fixing temperature is low, paper curl,
Trouble such as jamming is less likely to occur, and quick printing can be done in less time than reaching the set temperature.
Further, since the transfer and the fixing are performed at the same time and the linear pressure is low, the scattering of the toner, the collapse of the fine lines and the blurring of the image are reduced, the image quality is improved, and the life of the fixing roller (pressure roller) is extended.

[0027]

【Example】

Production Example of Capsule Toner 70.0 parts by weight of styrene, 2-ethylhexyl acrylate
30.0 parts by weight, divinylbenzene 1.0 part by weight, carbon black "# 44" (manufactured by Mitsubishi Kasei) 10.0 parts by weight, 2,2'-
4.0 parts by weight of azobisisobutyronitrile and 9.5 parts by weight of 4,4'-diphenylmethane diisocyanate "Millionate MT" (manufactured by Nippon Polyurethane Industry Co., Ltd.) were added to an attritor (manufactured by Mitsui Miike Kakoki Co., Ltd.) and heated to 10 ° C. And dispersed for 5 hours to obtain a polymerizable composition. 30% by weight of this in 800 g of an aqueous colloidal solution containing 4% by weight of tricalcium phosphate, which was prepared in advance in a glass separable flask having a volume of 2 liters.
Was added, and the mixture was emulsified and dispersed for 2 minutes at 5 ° C. and a rotation speed of 10,000 rpm using a TK homomixer (made by Tokushu Kika Kogyo Co., Ltd.). A four-necked 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 installed in an electric heating mantle.
Resorcin 22.0 g, diethyl malonate 3.6 g, 1,4-diazabicyclo [2.2.2] octane 0.5 g, ion-exchanged water 40 g
Prepare a mixed solution of and mix with a dropping funnel while stirring.
It dripped over minutes. Then, while stirring under nitrogen, the temperature was raised to 80 ° C. and the reaction was performed for 10 hours. 10% after cooling
Dissolve the dispersant in aqueous hydrochloric acid, filter, wash with water, and then
The mixture was dried at 20 ° C. for 12 hours under reduced pressure at 20 mmHg and classified by an air classifier to obtain a capsule toner having an average particle diameter of 9 μm and a resin having a thermally dissociable urethane bond. The glass transition point derived from the resin in the core material is 30.2 ° C, and the softening point is 130.
It was 0 ° C.

Next, an embodiment using the above-mentioned capsule toner in the present invention will be described in detail with reference to the drawings. As an example of the image forming method of the present invention, conceptual diagrams thereof are shown in FIGS. 1 and 2. 1 is an application device, 3 is a developing device, 7 is an insulating endless film belt, 9 is toner, 4
Is a heater for heating, and 5a and 5b are fixing rollers (pressure rollers). The applying step is a step of forming an electrostatic latent image on an insulator, and the applying device 1 is arranged on the surface of the insulating endless type film belt 7 so as to face each other, and the insulating endless film is attached to a large number of pin electrodes. A pulse voltage is applied to the mold film belt 7 while driving the pin electrodes to cause discharge between the mold film belt 7 and the insulating endless film belt, and images such as characters or symbols are dot-printed on the insulating endless film belt. An electrostatic latent image is formed by supplying electric charges corresponding to the dots decomposed into. The developing step is a step of forming a toner image by attaching the toner 9 in the developing device 3 to the electrostatic latent image on the insulating endless film belt thus obtained.

The insulating endless film belt 7 used in the present invention is made of a fluororesin-based, polyester-based, polyimide-based, polyamide-based heat-resistant film having a thickness of 5 to 20 μm, a polypropylene film, a polyethylene film, cellophane, or the like, or a conductive film. Examples include layers coated with a dielectric. The insulating endless film belt 7 is stretched by at least a pair of rollers, for example, a fixing roller (pressure roller) 5a and a support roller 10 as shown in FIG. Alternatively, the number of rollers is not particularly limited, such as being stretched by three rollers as shown in FIG.

After the developing process, the toner on the endless film belt moves along with the rotational movement of the endless film belt which moves at a constant peripheral speed in the direction shown in the figure by a predetermined driving means (not shown). , Is conveyed to the fixing unit. On the other hand, as shown in FIG. 1 or 2, for example, the recording medium 6 such as recording paper is moved by an endless film belt by a conveying means such as a conveying belt 11 so as to be synchronized with the start end of the toner image. By being conveyed separately from the above, it is conveyed to a fixing roller which is a fixing unit.

The toner on the endless film belt is
The toner is preheated by a heating unit that preheats the toner during transportation, and the outer shell of the capsule toner is processed to such an extent that it is easily dissociated. That is, the heating means in the present invention is disposed on the inner surface side of the endless film belt so as to face the endless film belt, and the temperature of the surface of the toner from the back surface of the moving endless film belt is in the range of 40 to 120 ° C. A preheating heating element is used. If the heating temperature is lower than 40 ° C., the melting of the toner becomes insufficient, which is not preferable. On the other hand, if it exceeds 120 ° C., the fixing temperature becomes high, and the above-mentioned conventional fixing method has problems. If the heat applied to the endless film belt surface is generally too high, the fixing temperature becomes high and the recording paper curls, and if it is too low, the toner is insufficiently fixed and it becomes difficult to store the record. Since the fixing can be carried out at 40 ° C. to 120 ° C. as described above, such a problem hardly occurs. The heating heater 4 which is such a heating element may be of any type as long as it is a device capable of heating the endless film belt surface up to 120 ° C. at most. For example, a heat source such as a hot plate, a quartz heater lamp, a flash lamp, a heating belt, and a heating element can be used.

Next, a pressure roller is used as a fixing means for fixing the preheated toner on the recording medium under pressure, and the recording medium 6 is fixed by a pair of fixing rollers (pressure rollers) 5a and 5b. It is pinched and fixed via an endless film belt. That is, the fixing roller 5a and the fixing roller 5b are means for fixing the toner image on the endless film belt by pressing it onto the surface of the recording medium. In the usual fixing method, since fixing is performed at a high temperature, it is necessary to use heat-resistant silicone rubber or the like for the fixing roller. However, in the present invention, heat is not directly transmitted to the fixing roller, so that heat resistance is not particularly required. Therefore, 12
The material is not particularly limited as long as it is an elastic body having a softening point of 0 ° C. or higher, and a usual inexpensive elastic material can be used. Further, the linear pressure applied by the fixing roller (pressure roller) in this case is usually as small as 0.5 to 4 kg / cm, so that the service life is extended. The line pressure during fixing is
Generally, the lower the fixing temperature is, the higher the fixing temperature needs to be, and the conventional fixing method usually requires a linear pressure of 4 kg / cm or more. However, according to the present invention, the linear pressure is 4 kg / cm even though the fixing temperature is at most 120 ° C. as described above.
A sufficient fixing strength can be obtained at less than 2 kg / cm.

In the image forming method of the present invention,
Further, after the recording medium is pressed against the endless film belt and fixed by the fixing rollers (pressure rollers) 5a and 5b, a small amount of toner remaining on the endless film belt also serves to cool the insulating endless film belt 7. It may be provided with a cleaning means for removing. For example,
A cleaning web 8 as shown in FIG. 1 or 2 is used. The location of the cleaning web 8 is not particularly limited as long as it can remove the residual toner. For example, as shown in FIG. 1, the fixing roller (pressure roller) 5a.
Or facing the support roller 10 as shown in FIG. Further, residual charges are removed by a static eliminator 2 such as a conductive brush or a conductive roll, and the endless film belt 7 is returned to the initial state and reused. Further, after the toner is fixed on the recording medium in this way, the recording medium 6 fixed by the paper discharge means is discharged to the outside of the apparatus.

Endless type film belt 7, fixing roller 5a
And 5b, the support roller 10, and the conveyor belt 11 are rotated at a constant peripheral speed in the directions shown in the drawings by a predetermined driving means (not shown).

[0035]

The following effects can be obtained by using the image forming method of the present invention. (1) Since fixing is performed at a fixing temperature of 120 ° C. or less, the fixing device can be simplified, and the size and cost can be reduced. (2) Since fixing is performed at a fixing temperature of 120 ° C. or less, heat-resistant members are not required in the fixing device and its surroundings, and inexpensive materials can be used, resulting in a low-cost printing device. (3) Since fixing is performed at a fixing temperature of 120 ° C. or less and the linear pressure can be lowered, curling of the paper is less likely to occur, and paper clogging is less likely to occur, resulting in less maintenance. (4) Since fixing is performed at a fixing temperature of 120 ° C or less and a low linear pressure,
The fixing device and the members around the fixing device have a long life, which reduces maintenance. (5) Since the low temperature fixing toner is used, the temperature of the heat generating element in the fixing device can be set low, and the temperature rise is small. Therefore, noise can be reduced without the need for a forced heat dissipation device such as an electric fan to be reduced or installed in the machine. (6) Quick printing is possible because the waiting time required to heat the fixing device can be shortened. (7) Since the transfer and the fixing are performed at the same time and the fixing is performed with a low linear pressure, the image quality is high without the scattering of the image due to the scattering of the toner, the collapse of the fine line, and the blurring of the image. (8) Waste toner is not generated because the transfer efficiency of toner to paper is very high.

[Brief description of drawings]

FIG. 1 shows a conceptual diagram of an image forming method of the present invention.

FIG. 2 is a conceptual diagram of an image forming method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Applying device 2 Erasing device 3 Developing device 4 Heating heater 5a Fixing roller (pressure roller) 5b Fixing roller (pressure roller) 6 Recording medium 7 Insulating endless film belt 8 Cleaning web 9 Toner 10 Supporting roller 11 Conveying belt

Claims (6)

[Claims] 1. An applying step of forming an electrostatic latent image on an insulator, a developing step of attaching toner to the obtained electrostatic latent image to form a toner image, and the formed toner image on a recording medium. An image forming method comprising a fixing step of fixing, wherein the toner is a capsule toner composed of a heat-meltable core material containing at least 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 isothiocyanate compound in an amount of 0 to 30 mol% of the whole isocyanate compound and / or isothiocyanate compound, (2) 2
100 to 70 mol% of the isocyanate compound and / or isothiocyanate compound having a valency or more with respect to the whole isocyanate compound and / or isothiocyanate compound, and (3) a compound having one active hydrogen which reacts with the isocyanate group and / or the isothiocyanate group Of the whole compound which reacts with an isocyanate group and / or an isothiocyanate group
To 30 mol%, (4) out of 100 to 70 mol% of all compounds that react with an isocyanate group and / or an isothiocyanate group, a compound having two or more active hydrogens that react with an isocyanate group and / or an isothiocyanate group, (1) +
The ratio of the number of moles of (2) to the number of moles of (3) + (4) is from 1: 1.
At least 30% of the number of bonds involving all isocyanate groups and / or isothiocyanate groups in the resin, which is made of a resin reacted in the range of 1:20.
The above is a capsule toner that is a bond exhibiting thermal dissociation, the insulator is an endless film belt, and the toner on the endless film belt is preheated and then fixed under pressure. Image forming method. 2. The bond exhibiting thermal dissociation according to claim 1,
The image forming method according to claim 1, wherein the bond is derived from a reaction of a phenolic hydroxyl group and / or a thiol group with an isocyanate group and / or an isothiocyanate group. 3. The encapsulated toner according to claim 1, wherein the main component of the heat-fusible core material is a thermoplastic resin, and the glass transition point derived from the resin is 10 to 50 ° C. Item 1. The image forming method according to Item 1. 4. The image forming method according to claim 1, wherein the capsule toner according to claim 1 has a softening point of 80 to 150 ° C. 5. The image forming method according to claim 1, wherein the preheating temperature of the toner on the endless type film belt is 40 to 120 ° C. 6. The linear pressure in the fixing step is 0.5 to 4 kg.
/ Cm is the image forming method according to any one of claims 1 to 5.