JPH04353865A - Method for forming picture image - Google Patents

Abstract

PURPOSE:To make the device simple and small in size by using a specified interface polymn. type capsule toner and specifying the fixing temp. CONSTITUTION:A capsule toner comprising a shell and core material which melts heat and contains a colorant is used. The shell essentially consists of such a resin obtd. by the reaction of the following compds. They are univalent isocyanate compds. (A) by 0-30mol% of the total isocyanate compds and bivalent or higher valent isocyanate compds.(B) by 100-70mol% of the total isocyanate compds, compds. (C) having one active hydrogen which reacts with an isocyanate group by 0-30mol% of the total amt. of compds. which react with isocyanate groups, and compds. (D) having two or more hydrogen atoms by 100-70mol% of the compds. which react with isocyanate groups. These components are used by 1:1-1:20 ratio of (A+B):(C+D). Moreover, in couplings relating to all of isocyanate groups of the resin, >=30% in their number are couplings which dissociate by heat. The fixing process is performed at temp. between >=40 deg.C and <=120 deg.C.

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

BACKGROUND ART Conventionally, when forming images in copying machines, laser beam printers, etc., the Carlson method has generally been used (U.S. Pat. No. 2,221,776
, Nos. 2,297,691 and 2,357,809,
“Electrophotography: p22-p
41, R. M. Shaffert 1965, The
Focal Press). FIG. 2 shows a conceptual diagram of a conventional image forming method. In the conventional method, an electrostatic latent image formed on a photoreceptor by optical means is first developed in a developing step, and then transferred to a recording sheet in a transfer step. The image is transferred to a recording medium such as the like, and then fixed in a fixing step, generally by heat and pressure, to form an image. Since the photoreceptor is used repeatedly, a cleaning device is installed to clean residual toner after transfer as the photoreceptor rotates.

0003

[Problems to be Solved by the Invention] However, in the conventional image forming method, the temperature of the heating element of the fixing device is extremely high during the process from forming the electrostatic latent image to fixing it on the recording medium. and required a large amount of pressure. On the other hand, since the photoreceptor and the developing device need to be kept at room temperature, it is necessary to place a considerable distance between the fixing section and the photoreceptor and the developing device, which causes the device to become larger. Furthermore, it was necessary to forcibly remove the generated heat from the system, but the sound generated by the forced heat dissipation device is a noise that cannot be ignored in offices and the like.

[0004]Furthermore, since the fixing step exists independently and is at a high temperature of around 200° C., an expensive heat-resistant member such as heat-resistant resin or heat-resistant rubber is required around the fixing device. on the other hand,
When fusing at high temperatures, problems such as curling and jamming of the paper tend to occur, and depending on the thickness of the paper, the paper absorbs heat, so
It has also been pointed out that it causes poor fixation. Furthermore, if the fixing temperature is high, it takes time to reach the set temperature and quick printing cannot be performed, making it unsuitable for devices such as facsimiles that require quick printing. From these viewpoints, there is a demand for the development of a new image forming method and a toner suitable for the method.

[0005]

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present inventors have studied low-temperature melting toner shell materials. As a result, the inventors found that an interfacial polymerization type capsule toner produced by an interfacial polymerization method melts at a temperature below 120° C., and further studied an image forming method using this capsule toner, leading to the present invention.

That is, the image forming method of the present invention includes a charging step of charging a photoreceptor, an exposure step of exposing the photoreceptor, and adhering toner to the electrostatic latent image formed on the photoreceptor. In an image forming method comprising a developing step of forming a toner image, a transfer step of transferring the formed toner image to a recording medium, and a fixing step of fixing the transferred toner image to the recording medium, the toner is of an interfacial polymerization type. The capsule toner is composed of a heat-fusible core material containing at least a colorant, and an outer shell provided to cover the surface of the core material, and the main component of the outer shell is (1) monovalent. The isocyanate compound and/or isothiocyanate compound is 0 to 30 mol% of the total isocyanate compound and/or isothiocyanate compound, (2) isocyanate compound and/or isothiocyanate compound is isocyanate compound and/or isothiocyanate compound 100 to 70 mol% of the total, and (3) 0 to 30 of the total of the compounds that react with isocyanate groups and/or isothiocyanate groups, including a compound having one active hydrogen that reacts with isocyanate groups and/or isothiocyanate groups.
mole%, (4) a compound having two or more active hydrogens that reacts with isocyanate groups and/or isothiocyanate groups, out of 100 to 70 mole% of the total compounds that react with isocyanate groups and/or isothiocyanate groups;
It consists of a resin obtained by reacting the number of moles of (1) + (2) and the number of moles of (3) + (4) in the range of 1:1 to 1:20, and the total isocyanate group and /or Using a capsule toner in which at least 30% or more of the bonds involving isothiocyanate groups are bonds exhibiting thermal dissociation, and the fixing step is performed at a temperature of 40° C. or higher and 120° C. or lower. This is an image forming method characterized by the following.

[0007] Here, the thermally dissociable bond is a bond resulting from a reaction between a phenolic hydroxyl group and/or thiol group and an isocyanate group and/or isothiocyanate group. Specifically, the monovalent isocyanate compounds in (1) above include 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 isocyanate
-cyanophenyl, 3,4-dichlorophenyl isocyanate, o-tolyl isocyanate, m-tolyl isocyanate, p-tolyl isocyanate, p-toluenesulfonyl isocyanate, 1-naphthyl isocyanate, o-nitrophenyl isocyanate, m-nitrophenyl isocyanate, p-nitrophenyl isocyanate, phenyl isocyanate, p-bromophenyl isocyanate, o-methoxyphenyl isocyanate, m-methoxyphenyl isocyanate, p-methoxyphenyl isocyanate, ethyl isocyanatoacetate, Examples include monovalent isocyanate compounds such as butyl isocyanatoacetate and trichloroacetyl isocyanate.

Examples of the isocyanate compound having a valence of 2 or higher (2) include 2,4-tolylene diisocyanate, a dimer of 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, and p-xylylene diisocyanate. Diisocyanate, m-xylylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 1
, 5-naphthylene diisocyanate, 3,3'-dimethyl-diphenyl-4,4'-diisocyanate, 3,
Aromatic isocyanate compounds such as 3'-dimethyl-diphenylmethane-4,4'-diisocyanate, metaphenylene diisocyanate, triphenylmethane-triisocyanate, polymethylene phenyl isocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, lysine diisocyanate, dimer Aliphatic isocyanate compounds such as acid diisocyanates, isophorone diisocyanate, 4,4'
- Alicyclic isocyanate compounds such as methylene bis(cyclohexyl isocyanate), methylcyclohexane-2,4 (or 2,6) diisocyanate, 1,3-(isocyanatomethyl)cyclohexane, etc., 3 moles of tolylene diisocyanate and 1 mole of trimethylolpropane. Examples include isocyanate compounds such as adducts with. In addition, as compounds having an isothiocyanate group, phenyl isothiocyanate, xylylene-1,4
Examples include compounds such as -diisothiocyanate and ethyridine diisothiocyanate. Among them, compounds in which an isocyanate group is directly bonded to an aromatic ring are effective in lowering the thermal dissociation temperature after urethane bond formation, and are preferably used.

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

Examples of the compound having one active hydrogen that reacts with the isocyanate group and/or isothiocyanate group in (3) above include methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol, isobutyl alcohol, and t-butyl. alcohol, pentyl alcohol, hexyl alcohol,
Aliphatic alcohols such as 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-te
rt-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,
Compounds include aromatic alcohols such as benzyl alcohol, 1-naphthol, 2-naphthol, and 2-acetyl-1-naphthol, and amides such as ε-caprolactam.

Among them, phenol derivatives represented by the following formula (I) are preferably used.

[Formula 1] (wherein, R1, R2, R3, R4, R
5 is independently H or an alkyl group having 1 to 9 carbon atoms,
It represents an alkenyl group, an alkoxy group, an alkanoyl group, a carbalkoxy group, an aryl group, or a halogen. )

[0012] The isocyanate group and/or the above (4)
Among compounds having two or more active hydrogens that react with isothiocyanate groups, examples of dihydric or higher alcohol compounds include catechol, resorcinol, hydroquinone, 4-methylcatechol, 4-t-butylcatechol, 4-acetylcatechol. , 3-methoxycatechol,
4-phenylcatechol, 4-methylresorcinol, 4-
Ethylresorcin, 4-t-butylresorcin, 4-hexylresorcin, 4-chlororesorcin, 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-hydroxyphenylacetate, resorcin mono-2-hydroxyethyl ether, hydroxyhydroquinone , gallic acid, ethyl 3,4,5-trihydroxybenzoate, and the like. Among these, catechol derivatives represented by the following formula (II) or resorcinol derivatives represented by the following formula (III) are preferably used.

[0013]

[Formula 2] (In the formula, R6, R7, R8, R9 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 a halogen. show.)

embedded image (wherein R10, R11, R12, R13 are independently H, or an alkyl group having 1 to 6 carbon atoms, an alkenyl group,
It represents an alkoxy group, an alkanoyl group, a carbalkoxy group, an aryl group, or a halogen. )

Other examples of compounds having at least one functional group other than a hydroxyl group that react 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-
Hydroxybenzoic 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-hydroxynaphthoic acid, 2-hydroxynaphthoic acid, 3-hydroxynaphthoic acid, 4-hydroxyphthalic acid, and the like.

[0015] Examples of 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-mercaptoacetate) mercaptopropionate), trimethylolethane tris (2-mercaptoacetate), trimethylolethane tris (3-mercaptopropionate), pentaerythritol tetrakis (2-mercaptoacetate), pentaerythritol tetrakis (3-mercaptopropionate) ),
Dipentaerythritol hexakis (2-mercaptoacetate), dipentaerythritol hexakis (3-mercaptoacetate)
mercaptopropionate), 1,2-dimercaptobenzene, 4-methyl-1,2-dimercaptobenzene, 3,6-dichloro-1,2-dimercaptobenzene, 3,4,5,6-tetrachloro -1,2-dimercaptobenzene, xylylene dithiol, 1,3,
Examples include 5-tris(3-mercaptopropyl)isocyanurate.

In the thermally dissociable outer shell resin used in the present invention, the thermally dissociable bonds are all isocyanate groups and/or
Of the bonds involving isothiocyanate groups, at least 30% or more is required, preferably 50%. This thermally dissociable bond is 30 times the number of bonds involving all isocyanate groups and/or isothiocyanate groups.
If it is less than %, the capsule outer shell strength will not be sufficiently reduced during heat-pressure fixing, and the excellent fixing performance of the core material will not be brought out.

In the capsule toner of the present invention, 30% of the total bonds involving isocyanate groups and/or isothiocyanate groups are due to reactions with phenolic hydroxyl groups and/or thiol groups.
phenolic hydroxyl groups and/or
or compounds having functional groups other than thiol groups that react with isocyanate groups, such as active methylene group-containing compounds such as malonic acid esters and acetoacetic esters, oximes such as methyl ethyl ketone oxime, carboxylic acids, polyols, polyamines, Aminocarboxylic acids, aminoalcohols, etc. can be used as shell-forming substances.

In the present invention, the compound having one active hydrogen that reacts with the isocyanate group and/or isothiocyanate group in (3) above is
or 30 of the total compound that reacts with the isothiocyanate group.
It can be used up to mol %, but if it exceeds 30 mol %, the storage stability of the capsule toner deteriorates, which is not preferable. In addition, the number of moles of the isocyanate compound and/or isothiocyanate compound [(1) + (2)] constituting the outer shell and the compound [(3) + (4)] that reacts with the isocyanate group and/or isothiocyanate group The ratio is 1:1 to 1: in order to prevent unreacted isocyanate groups from remaining.
20 is preferred.

In the production of capsule toner, the outer shell is preferably formed by interfacial polymerization or in-situ polymerization. It may be carried out by a dry method in which the outer shell is formed by stirring the outer shell-forming material child particles having a particle diameter of /8 or less at high speed in an air current.

The resin used for the core material of the capsule toner in the present invention has a glass transition point (Tg) of 10°C.
Thermoplastic resins such as polyester resins, polyester/polyamide resins, polyamide resins, and vinyl resins having a temperature of 50° C. or less can be mentioned, and vinyl resins are particularly preferred. If the glass transition point is less than 10°C, the storage stability of the capsule toner deteriorates, and if it exceeds 50°C, the fixing strength of the capsule toner deteriorates, which is not preferable.

Examples of monomers constituting the vinyl resin include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, and p-methylstyrene.
Styrene or styrene derivatives such as ethylstyrene, 2,4-dimethylstyrene, p-chlorostyrene, vinylnaphthalene, ethylenically unsaturated monoolefins such as ethylene, propylene, butylene, isobutylene, etc., such as vinyl chloride, vinyl bromide, etc. , vinyl fluoride,
Vinyl esters such as vinyl acetate, vinyl propionate, vinyl formate, vinyl caproate, etc., such as acrylic acid, methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-acrylate
-Butyl, isobutyl acrylate, t-butyl acrylate, amyl acrylate, cyclohexyl acrylate, n-octyl acrylate, isooctyl acrylate, decyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, acrylic Methoxyethyl acrylate, 2-hydroxyethyl acrylate, glycidyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, methyl α-chloroacrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, methacrylate Isopropyl acid, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, amyl methacrylate, cyclohexyl methacrylate, n-octyl methacrylate, isooctyl methacrylate, decyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate , stearyl methacrylate, methoxyethyl methacrylate, 2-hydroxyethyl methacrylate, glycidyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, etc. and ethylenic monocarboxylic acids and their esters, such as acrylonitrile, Substituted ethylenic monocarboxylic acids such as methacrylonitrile, acrylamide, etc., ethylenic dicarboxylic acids such as dimethyl maleate and substituted products thereof, vinyl ketones such as vinyl methyl ketone, vinyl ethers such as vinyl methyl ether, etc. vinylidene halides such as vinylidene chloride, e.g. N-vinylpyrrole, N-
There are N-vinyl compounds such as vinylpyrrolidone and the like. Preferably, among 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 properties 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.

[0022] When adding a crosslinking agent to the monomer composition constituting the resin for the core material according to the present invention, known crosslinking agents can be used as appropriate (two or more types in combination as necessary). . If these crosslinking agents are used in large amounts, the toner becomes difficult to melt with heat, resulting in poor heat fixing properties or heat pressure fixing properties. Furthermore, if the amount used is small, it becomes difficult to prevent an offset phenomenon in which a portion of the toner does not completely adhere to the paper and adheres to the roller surface and is transferred to the next paper during heat-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 during heat-pressure fixing. The ratio of these anti-offset agents to the resin in the core material is preferably 1 to 20% by weight.

Although a coloring agent is contained in the core material of the capsule toner of the present invention, all the dyes, pigments, etc. used in conventional colorants for toners can be used. Usually, about 1 to 15 parts by weight is used per 100 parts by weight of the resin in the core material.

In addition, the shell material of the capsule toner of the present invention contains metal-containing dyes such as metal complexes of organic compounds having carboxyl groups or nitrogen groups, nigrosine, etc., which have been conventionally used in toners, as charge control agents. may be added in an appropriate amount. Further, this charge control agent can also be used in combination with a toner.

[0025] The capsule toner of the present invention may contain a fluidity improver, a cleanability improver, and the like, if necessary. Furthermore, additives for adjusting the developability, such as fine particle powder of a polymer of methacrylic acid methyl ester, etc. may be used. Furthermore, a small amount of carbon black may be used for color toning, resistance adjustment, etc.

[0026] The softening point of the capsule toner in the present invention is preferably 80°C or more and 150°C or less,
If the temperature is less than 80°C, offset resistance deteriorates, and if it exceeds 150°C, fixing strength deteriorates, which is not preferable. Although the particle size of the capsule toner in the present invention is not particularly limited, the average particle size is usually 3 to 30 μm. The thickness of the outer shell of the capsule toner is preferably 0.01 to 1 .mu.m. If it is less than 0.01 .mu.m, the blocking resistance will deteriorate, and if it exceeds 1 .mu.m, the thermal meltability will deteriorate, which is not preferable.

Further, in the image forming method of the present invention, the linear pressure in the fixing step can be set to less than 4 kg/cm. Further, as a heat source of the fixing device, a heating element or a heat roller via an endless film is used. Further, heat is radiated by using a honeycomb type cooler in the fixing device.

[0028]

[Function] According to the present invention, since the fixing temperature can be set very low using the interfacially polymerized capsule toner, there is little need for forced heat radiation. Therefore, the heat dissipation device is greatly reduced in size and noise is significantly reduced. Also, since the fixing temperature is very low,
Problems such as paper curling and jamming are less likely to occur. In addition, since the fixing temperature is low, it does not take long to reach the set temperature, allowing quick printing.

[0029]

[Example] Production example of capsule toner 70.0 parts by weight of styrene, 30.0 parts by weight of 2-ethylhexyl acrylate, 1.0 parts by weight of divinylbenzene, 1 part by weight of carbon black "#44" (manufactured by Mitsubishi Kasei Corporation)
0.0 parts by weight, 4.0 parts by weight of 2,2'-azobisisobutyronitrile, and 9.5 parts by weight of 4,4'-diphenylmethane diisocyanate "Millionate MT" (manufactured by Nippon Polyurethane Kogyo Co., Ltd.), The mixture was poured into an attritor (manufactured by Mitsui Miike Kakoki) and dispersed at 10° C. for 5 hours to obtain a polymerizable composition. This was added to 800 g of a 4% by weight aqueous colloidal solution of tricalcium phosphate prepared in advance in a 2 liter separable glass flask.
Add only the amount to give 0% by weight, and mix at 5°C and 10,000 rotations using a TK homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.).
The mixture was emulsified and dispersed at rpm for 2 minutes. It was covered with a four-necked glass lid, equipped with a reflux condenser, a thermometer, a dropping funnel with a nitrogen introduction tube, and a stainless steel stirring bar, and placed in an electric heating mantle. 22.0 g of resorcin, 3.6 g of diethyl malonate,
1,4-diazabicyclo[2.2.2]octane 0
．． A mixed solution of 5 g and 40 g of ion-exchanged water was prepared and added dropwise from the dropping funnel over 30 minutes with stirring. Thereafter, the temperature was raised to 80°C while stirring under nitrogen.
The reaction was allowed to proceed for 10 hours. After cooling, the dispersant was dissolved in a 10% aqueous hydrochloric acid solution, filtered, washed with water, dried at 45°C for 12 hours under reduced pressure of 20 mmHg, and classified using an air classifier. A capsule toner made of a resin having a dissociable urethane bond was obtained. The glass transition point derived from the resin in the core material is 30.2℃, and the softening point is 1
The temperature was 30.0°C.

Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a conceptual diagram of the image forming method of the present invention. Reference numeral 1 denotes a photoreceptor drum such as amorphous silicon or organic photoreceptor having a photoreceptor layer provided on a conductive support. Practical photoreceptors such as selenium-based, silicon-based, and organic-based photoreceptors are exemplified as photoreceptors, and any of them may be used.

Reference numeral 7 denotes a charging device, which is provided facing the photoreceptor 1. The charging means is not particularly limited, and for example, a corona charger, a brush charger, a roller charger, or the like can be used.

Reference numeral 2 denotes an exposure device, which is installed facing the photoreceptor 1 and forms an electrostatic latent image on the surface of the photoreceptor. As the exposure device 2, a light source such as a laser, an LED, or an EL array is used in combination with an imaging optical system. Alternatively, it is possible to use a device such as an optical system that projects reflected light from a document, which is generally used in copying machines.

Reference numeral 3 denotes a developing device, which is disposed opposite to the photoreceptor 1 and is used to visualize the electrostatic latent image formed on the surface of the photoreceptor with toner. As the developing device, any commonly used developing device such as a two-component magnetic brush developing device, a one-component magnetic brush developing device, a one-component non-magnetic developing device, etc. can be used. The toner used in the present invention is an interfacial polymerization type capsule toner, which is the above-mentioned capsule toner produced by an interfacial polymerization method.

The toner adhering to the electrostatic latent image formed on the photoreceptor is transferred onto the recording medium 6 by the transfer device 5b. Transfer methods include the corona transfer method, which applies corona ions to the back side of the recording medium, the roller transfer method, which presses a conductive roller to which voltage is applied to the back side of the recording medium and forms a transfer electrolyte using the voltage, and the roller transfer method, which applies the transfer of the recording medium to the back surface of the recording medium. There are dielectric belt transfer methods that also serve as a method, and any of them can be applied to the method of the present invention.

A cleaning device 8 such as a cleaning web is installed opposite the photoreceptor 1 to remove a small amount of toner remaining on the photoreceptor after the transfer process. The fixing section includes 4 heaters, 12 fixing rollers, and 11 heaters.
It is equipped with an endless film. Alternatively, 14 heat rollers and 14 fixing rollers 5 are provided.

When an endless film is used, the heater 4 is arranged so as to heat the surface of the recording medium in advance through the endless film in order to fix the toner. The method does not matter as long as it is a device that can heat up to ℃. Further, the endless film itself may be of a type that generates heat when energized, and in that case, no heater is required. Examples of heating elements for heating heaters include hot plates,
Heat sources such as quartz heater lamps, flashlights, heating belts, heating elements, etc. can be used.

[0037] Endless films are not limited to heat-resistant films such as fluororesin, polyimide resin, polyamide resin, and polyester resin, and since the heating temperature can be set low,
Polypropylene film, polyethylene film, cellophane, etc. can also be used. For endless film, support roller 1
It is stretched by 6.

The fixing roller 12 is a means for pressing and fixing the recording medium having the transferred toner image onto the endless film surface. Normal fixing devices perform fixing at high temperatures, so it is necessary to use heat-resistant silicone rubber or the like for the fixing roller. However, in the present invention, the fixing roller is in contact with the back side of the recording medium and heat is not transferred directly, so this is especially important. Heat resistance is not required. Therefore, the material is not particularly limited as long as it is an elastic body with a softening point of 120° C. or higher, and ordinary inexpensive elastic materials can be used. Furthermore, since the linear pressure can be as small as less than 4 kg/cm, the service life is also extended.

When a heat roller is used for fixing, heat-resistant films such as fluororesin, polyimide resin, polyamide resin, polyamide-imide resin, etc. are conventionally used for the heat roller part, but in the present invention, the fixing temperature is low. Therefore, when a conventional heat-resistant film is used, its service life is extended, and films made of polyester resin, polypropylene resin, polyethylene resin, etc., and cellophane can also be used. The fixing roller 12 is the same as in the case where the endless type film is used.

The recording paper 6, which is a recording medium, is conveyed by a conveyor belt 15 along the surface of the endless film 11, as shown in FIG. The toner image is fixed between the fixing roller 12 and the endless film 11, and is then ejected from the apparatus by a paper ejecting means. Alternatively, as shown in FIG. 8, the sheet is conveyed by a conveyor belt 15, fixed between a heat roller 14 and a fixing roller 12, and then discharged.

Reference numeral 13 denotes a heat radiator, and in the method of the present invention, a honeycomb type heat radiator can be used in place of the conventionally used forced heat radiator such as an electric fan. The cross-sectional shape is square, rectangle, parallelogram, regular hexagon, etc.
Not particularly limited. The heat radiator 13 is for discharging the heat generated in the fixing section, and is installed so that the airflow flows from the bottom to the top in a substantially vertical direction to facilitate heat dissipation. Further, the material may be a metal plate such as an aluminum plate or a stainless steel plate, or a plastic plate such as an acrylic plate or a Bakelite plate. In the present invention, since the fixing temperature is low, sufficient heat radiation can be achieved by providing the honeycomb type heat radiator as described above.

The photoreceptor 1, the endless film 11, the heat roller 14, and the fixing roller 12 are rotated at a constant circumferential speed in the directions shown in each figure by a predetermined driving means (not shown).

Next, each step of the image forming method of the present invention having the above structure will be explained. Figure 3 shows the charging process, Figure 4
5 shows an exposure process, FIG. 5 shows a developing process, FIG. 6 shows a transfer process, and FIGS. 7 and 8 show a fixing process. In the charging step, as shown in FIG. 3, a predetermined charge is uniformly applied to the surface of the photoreceptor by, for example, a corona charger 7. Here, a photoreceptor sensitive to positive charges is taken as an example, and a photoreceptor layer 1 is placed on the surface of the conductive support 1b.
a is coated to form a photoreceptor 1. This photosensitive layer 1a
A uniform charge is applied by the corona charger 7 to charge the surface of the photosensitive layer 1a with positive polarity.

In the exposure step, as shown in FIG. 4, the surface of the photoreceptor is irradiated with light emitted from the exposure device 2, and charges leak only in the exposed portions, forming an electrostatic latent image on the photoreceptor layer 1a. .

In the developing step, as shown in FIG. 5, the toner triboelectrically charged in the developing device is carried through the rotating sleeve 3a, adheres to the photoreceptor surface in accordance with the charge on the photoreceptor surface, and is developed. There are two types of development processes: regular development, in which toner of the opposite polarity to the electric charge is attached by Coulomb force to an area where there is an electric charge, and reversal development, in which toner is attached to an area where the electric charge has been erased by irradiation with light. Although the developing process of the present invention can be used for any of these methods, FIG. 5 shows an example of regular development.

In the transfer process, as shown in FIG. 6, the toner image on the surface of the photoreceptor is transferred to the recording medium 6 by a transfer corotron, a transfer roller, etc. by receiving electric charge from the back side of the recording medium 6 such as recording paper. Although some untransferred toner remains on the surface of the photoreceptor, it is removed by a cleaning device 8 such as a cleaning web provided facing the photoreceptor as shown in FIG.

In the fixing step, when an endless film as shown in FIG. 7 is used, the toner image transferred to the surface of the recording medium 6 is transferred by the heater 4 through the transparent endless film 11 without contact. After being heated in advance, it passes between the fixing roller 12 and the endless film 11 and receives pressure, thereby being more strongly fixed on the recording medium 6. Further, when a heat roller is used as shown in FIG. 8, the image is fixed on the recording medium 6 by passing between the heat roller 14 and the fixing roller 12 and receiving pressure in the same manner as described above.

In the present invention, in order to melt the toner transferred to a recording medium such as a recording paper, whether an endless film or a heat roller is used, 40
Heated at a temperature range of ~120°C. If the temperature is lower than 40°C, the toner will not be sufficiently melted, which is not preferable. Further, when the temperature exceeds 120° C., the fixing temperature becomes high, which causes the above-mentioned problems with the conventional method. In addition, the linear pressure during fixing generally needs to be higher as the fixing temperature is lower.
Conventional methods usually require a linear pressure of 4 kg/cm or more. However, according to the present invention, the fixing temperature is at most 120°C.
Despite this, the linear pressure is less than 4 kg/cm, often 2 kg/cm.
Sufficient fixing strength can be obtained at less than kg/cm. Generally, if the heat applied to the surface of the recording medium is too high, the recording paper will curl, and if it is too low, the fixation of the toner will be insufficient, making it difficult to preserve the recording. Since fixing can be performed at a temperature of 120° C. to 120° C., such problems are unlikely to occur.

On the other hand, when the development and transfer steps of the photoreceptor 1 are completed, the remaining charges are neutralized by a charge eliminating device 9 such as a charge eliminating lamp, and the photoreceptor 1 returns to the charging step and is reused. It should be noted that the present invention is not limited to the above embodiments, and specifications such as the type of each device and the process can be changed based on the principles of the present invention.

[0050]

[Effects of the Invention] According to the image forming method of the present invention, (1)
Since fixing is performed at a fixing temperature of 120° C. or lower, the fixing device is simple and can be made smaller and cheaper. (2) Since fixing is performed at a fixing temperature of 120° C. or lower, there is no need for heat-resistant members in the fixing device and its surroundings, allowing the use of inexpensive materials, resulting in a low-cost printing device. (3) Since fusing is performed at a fusing temperature of 120°C or less and the linear pressure can be lowered, paper curling and paper clogging are less likely to occur, resulting in reduced maintenance. (4) Since fixing is performed at a fixing temperature of 120° C. or less and a low linear pressure, the life of the fixing device and its surrounding parts is extended, resulting in reduced maintenance. (5) Since toner that is fixed at a low temperature is used, the temperature of the heating element in the fixing device can be set low, and the temperature rise is small. Therefore, it is sufficient to reduce the size of the forced heat radiating device such as an electric fan in the machine or to radiate heat using the honeycomb type cooler of the present invention, thereby solving the noise problem. (6) Quick printing is possible because the waiting time required to raise the temperature of the fixing device can be shortened.

[Brief explanation of drawings]

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

FIG. 2 shows a conceptual diagram of a conventional image forming method.

FIG. 3 is a conceptual diagram showing a charging step in the image forming method of the present invention.

FIG. 4 is a conceptual diagram showing an exposure step in the image forming method of the present invention.

FIG. 5 is a conceptual diagram showing a developing step in the image forming method of the present invention.

FIG. 6 is a conceptual diagram showing a transfer step in the image forming method of the present invention.

FIG. 7 is a conceptual diagram showing a case in which a heater via an endless film is used as a heat source in the fixing step in the image forming method of the present invention.

FIG. 8 is a conceptual diagram showing a case where a heat roller is used as a heat source in the fixing step in the image forming method of the present invention.

[Explanation of symbols]

1 Photoreceptor 1a Photosensitive layer 1b Conductive support 2 Exposure device 3 Developing device 3a Rotating sleeve 4 Heating heater 5b Transfer device 6 Recording medium (recording paper) 7　Charging device 8 Cleaning device 8a　Collected toner box 9 Static eliminator 10 Toner 11 Endless film 12 Fixing roller 13 Heatsink 14 Heat roller 15 Conveyor belt 16 Support roller

Claims (7)

[Claims] Claim 1: A: a charging step of charging a photoreceptor, and B:
C. A developing step of attaching toner to the electrostatic latent image formed on the photoreceptor to form a toner image; D. Transferring the formed toner image to a recording medium. In an image forming method comprising a transfer step and a fixing step of fixing the transferred toner image on a recording medium, the toner is an interfacially polymerized capsule toner, and a heat-melting core material containing at least a colorant; and an outer shell provided to cover the surface of the core material, and the main components of the outer shell are (1) monovalent isocyanate compounds and/or isothiocyanate compounds, isocyanate compounds and/or isothiocyanate compounds as a whole; (2) 100 to 70 mol% of the total isocyanate compound and/or isothiocyanate compound, (3) isocyanate group and/or isothiocyanate 0 to 30 of all compounds that react with isocyanate groups and/or isothiocyanate groups, including compounds having one active hydrogen that reacts with groups.
mole%, (4) a compound having two or more active hydrogens that reacts with isocyanate groups and/or isothiocyanate groups, out of 100 to 70 mole% of the total compounds that react with isocyanate groups and/or isothiocyanate groups;
It consists of a resin obtained by reacting the number of moles of (1) + (2) and the number of moles of (3) + (4) in the range of 1:1 to 1:20, and the total isocyanate group and /or Using a capsule toner in which at least 30% or more of the bonds involving isothiocyanate groups are bonds exhibiting thermal dissociation, and the fixing step is performed at a temperature of 40° C. or higher and 120° C. or lower. An image forming method characterized by: 2. A claim characterized in that the thermally dissociable bond according to claim 1 is a bond derived from a reaction between a phenolic hydroxyl group and/or thiol group and an isocyanate group and/or isothiocyanate group. Item 1. Image forming method according to item 1. 3. The capsule 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. 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. [Claim 5] The linear pressure in the fixing step is 4 kg/cm.
2. The image forming method according to claim 1, wherein 6. The image forming method according to claim 1, wherein the heat source of the fixing device is a heating element via an endless film or a heat roller. 7. The image forming method according to claim 1, wherein heat is radiated using a honeycomb type cooler.