JPH05197190A - Image forming method - Google Patents

Abstract

PURPOSE:To prevent the occurrence of a curl or a jam of a transparency sheet by using a thermal dissociation type capsule toner or a noncrystalline polyester outer shell papsule toner, an specifying the softening point and fixing tempera ture of a recording medium. CONSTITUTION:A thermal dissociation type capsule toner or a capsule toner having an outer shell made of noncrystalline polyester is used in this image forming method. The thermal dissociation type capsule toner is a toner having a shell weakened for its structure by heat, capable of being fixed by pressure at a low temperature, and incorporating a thermoplastic core containing at least thermoplastic resin and a coloring agent. A recording medium having the softening point of 100-200 deg.C is used, and the fixing process is performed under the temperature condition of 60-120 deg.C. A film having a low softening point can be used when a transparency sheet is used as the recording medium, the fixing temperature is very low, thus troubles such as a curl or a jam of the recording medium hardly occur.

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 forming an image in a copying machine, a laser beam printer, or the like, the Carlson method is generally used (US Pat. Nos. 2,221,776, 2,297,6).
91 and 2,357,809, "Electrophotography: p22-p41, 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 photoconductor by an optical means is first developed in a developing step,
An image is formed by being transferred onto a recording medium such as recording paper in a transfer step and then generally fixed by heat and pressure in a fixing step. Since the photosensitive member is repeatedly used, a cleaning device is installed to clean the residual toner after transfer as the photosensitive member rotates.

[0004]

However, in the conventional image forming method, the temperature of the heating element of the fixing device becomes extremely high during the process from the formation of the electrostatic latent image to the fixing to the recording medium. (Usually around 200 ° C.) and required a large pressure (usually 2.0 to 6.0 kg / cm). 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 section and the photoconductor and the developing device, which causes the device to become large. Further, it was necessary to forcibly remove the generated heat outside the system, but the sound generated by the forced heat dissipation device is a noise that cannot be ignored in offices and the like.

Further, as described above, in the conventional image forming method, since the fixing step exists independently and the temperature is as high as about 200 ° C., expensive heat-resistant resin, heat-resistant rubber, etc. are provided around the fixing device. A heat resistant member was required.

On the other hand, it has been pointed out that when fixing at a high temperature, problems such as curling and jamming of the paper are likely to occur, and the paper absorbs heat depending on the thickness of the paper, resulting in poor fixing. In particular, when a transparency sheet is used as the recording medium, a film having a softening point of 220 ° C. or higher such as a polyethylene terephthalate film or a polyimide film is usually used because heat resistance is required.
Above all, the melting point is about 260 ° C, and the maximum usable temperature is 150.
℃ polyethylene terephthalate film is commonly used, but it is also expensive in price, and because it is used near the upper limit of the operating temperature limit, it may become unusable due to curling when placed on the film immediately after fixing. It has been pointed out that there are many problems such as film jamming on the fixing roller. From these viewpoints, development of a new image forming method and a toner adapted to it is desired.

Therefore, an object of the present invention is to have a softening point of 100.
To provide a novel image forming method which has various effects such as curling and jamming of a transparency sheet by using a recording medium having a temperature of up to 200 ° C., and which saves maintenance. It is in.

[0008]

Therefore, the present inventors have studied a low temperature melting toner shell material in order to solve the above problems. As a result, it was found that the thermal dissociation type capsule toner produced by the interfacial polymerization method or the like and the capsule toner having an outer grain of amorphous polyester are melted at less than 120 ° C. Further, regarding the image forming method using these capsule toners The present invention has been studied and reached the present invention.

That is, in the image forming method of the present invention, a charging step of charging the photoconductor, an exposure step of exposing the photoconductor, and a step of attaching toner to the electrostatic latent image formed on the photoconductor In an image forming method, which comprises 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 a thermal dissociation type. An image forming method, characterized in that the toner is a capsule toner or a capsule toner in which outer grains are made of amorphous polyester, and the fixing step is performed under a temperature condition of 60 to 120 ° C. using a recording medium having a softening point of 100 to 200 ° C. Is.

As the recording medium, a polyethylene film, polypropylene film, cellophane, polycarbonate film, polymethylmethacrylate film, or polymethylpentene film is used.
The linear pressure in the fixing step is set to 0.01 to 4 kg / cm.

According to the present invention, the fixing temperature can be set extremely low by using the heat dissociation type capsule toner or the capsule toner in which the outer grains are made of amorphous polyester. Therefore, when the transparency sheet is used as the recording medium, Since a film having a low softening point can be used and the fixing temperature is very low, problems such as curling and jamming of the recording medium are less likely to occur.

The image forming method of the present invention will be described in detail with reference to the drawings. In the image forming method of the present invention, a softening point of 100 to 200 is used by using a heat dissociation type capsule toner or a capsule toner in which an outer grain is made of amorphous polyester.
The charging step, the exposing step, the developing step, the transferring step and the fixing step are not particularly limited as long as the recording medium at a temperature of 60 ° C. can be fixed at a fixing temperature of 60 to 120 ° C. to form an image. It may be a system. FIG. 1 is a conceptual diagram of an example of the image forming method of the present invention.

Reference numeral 1 is a photosensitive drum such as an amorphous silicon or organic photosensitive member having a photosensitive layer provided on a conductive support. Examples of the photoconductor include selenium-based, silicon-based, and organic-based photoconductors that have been put into practical use, and any of these may be used.

Reference numeral 7 denotes a charging device, which is provided so as to face the photoconductor 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 so as to face the photoconductor 1 and forms an electrostatic latent image on the photoconductor surface. As the exposure device 2, a light source such as a laser, an LED or an EL array is used in combination with an image forming optical system. Alternatively, an apparatus such as an optical system that projects reflected light of a document, which is generally used in a copying machine, can be used.

Reference numeral 3 denotes a developing device, which is installed opposite to the photoconductor 1 and is a developing device for visualizing the electrostatic latent image formed on the photoconductor surface with toner. As the developing device, any developing device such as a two-component magnetic brush developing device, a one-component magnetic brush developing device and a one-component non-magnetic developing device which are normally used can be used.

The toner used in the present invention is a thermal dissociation type capsule toner and a capsule toner in which the outer grain is made of amorphous polyester. The thermal dissociation type capsule toner is a toner having a shell having a property that the shell structure is weakened by heat and encapsulating a thermoplastic core material containing at least a thermoplastic resin and a colorant that can be fixed by pressure at a low temperature. Is.
The capsule toner in which the outer grain is made of amorphous polyester means at least one selected from the group consisting of divalent alcohol monomers and trivalent or higher polyvalent alcohol monomers.
At least a thermoplastic resin and a colorant, and an amorphous polyester obtained by polycondensation of at least one kind selected from the group consisting of a divalent carboxylic acid monomer and a trivalent or higher polyvalent carboxylic acid monomer. It is a toner obtained by coating the surface of a thermoplastic core material containing. That is, the structure of the shell of these toners is changed by 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 microcapsules are formed from a simple emulsion through a complex emulsion by (3) a core substance solution or dispersion is W / O or O
/ W type emulsion system, at the same time collecting the shell material monomer (A) at the interface, in the next step the interfacial polymerization method in which the monomer (B) and the monomer (A) react, in addition to in situ
The u polymerization method, the liquid hardening coating method, the air suspension coating method, the electrostatic coalescence method, the vacuum vapor deposition coating method and the like can be mentioned.

In the present invention, the thermal dissociation type capsule toner produced by the interfacial polymerization method and the spray drying method and the capsule toner produced by the in situ polymerization method in which the outer grain is made of amorphous polyester are preferably used. .. The interfacial polymerization method and the in situ polymerization method not only facilitate the functional separation of the core material and the shell material, but also can produce a uniform toner in an aqueous system. Further, in these polymerization methods, it is possible to obtain a toner having preferable properties in terms of toner fixability, such as the use of a substance having a low softening point as a core material.

As the shell material, a styrene resin (JP-A-58)
-205162), a polyamide-based resin (Japanese Patent Laid-open No. Sho 5)
8-66948), an epoxy resin (JP-A-59).
No. 148066), a polyurethane resin (JP-A-57-179860) and a polyurea resin (JP-A-62-150262) 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 for use as an outer grain of the heat dissociative capsule toner of the present invention. The main component of the 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, the heat dissociable urethane resin, which is the main component of this shell material,
Of the bonds involving all isocyanate groups and / or isothiocyanate groups, phenolic hydroxyl groups and / or
Alternatively, the number of bonds by reaction with a thiol group is 30% or more. For example, a resin obtained by reacting an isocyanate compound and / or an isothiocyanate compound with a compound having a phenolic hydroxyl group and / or a thiol group is preferably used (JP-A-4-2).
12169 publication).

Specifically, for example, the capsule toner comprises 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 an isothiocyanate compound in an amount of 0 to 30 mol% of the whole isocyanate compound and / or isothiocyanate compound, and (2) a divalent or higher valent isocyanate compound and / or The isothiocyanate compound is 100 to 70 mol% of the whole isocyanate compound and / or isothiocyanate compound, and (3) the isocyanate group and / or
Or 0 to 30 mol% of the whole compound reacting with an isocyanate group and / or an isothiocyanate group with a compound having one active hydrogen that reacts with an isothiocyanate group, (4) an activity of reacting with an isocyanate group and / or an isothiocyanate group Of 100 to 70 mol% of the whole compound which reacts a compound having two or more hydrogens with an isocyanate group and / or an isothiocyanate group, (1) + (2) mole number and (3)
+ (4) to the number of moles of the resin which is reacted in a ratio of 1: 1 to 1:20, and the number of bonds among all the isocyanate groups and / or isothiocyanate groups in the resin In the case of at least 30% or more, a capsule toner having a bond showing a thermal dissociation property can be mentioned.

As the bond exhibiting the thermal dissociation property, there may be mentioned 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.

Further, in such capsule toner, 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. The softening point of such a capsule toner is 8
What is 0-150 degreeC is used.

In the capsule toner in which the outer grain is made of amorphous polyester, the amorphous polyester is at least one selected from the group consisting of dihydric alcohol monomers and trihydric or higher polyhydric alcohol monomers, Obtained by polycondensation of at least one selected from the group consisting of divalent carboxylic acid monomers and trivalent or higher polyvalent carboxylic acid monomers (patent application dated September 1, 1992, reference number: KAP9
2-0894).

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

Examples of trihydric or higher alcohol components include sorbitol, 1,2,3,6-hexanetetrol, and 1,4.
-Sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,
4-butanetriol, trimethylolethane, trimethylolpropane, 1,3,5-trihydroxymethylbenzene and the like can be mentioned. Preferably, trihydric alcohol is used. In the present invention, these dihydric alcohol monomers and polyhydric alcohol monomers having a valence of 3 or more may be used alone or in combination.

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

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

The method for producing the amorphous polyester in the present invention is not particularly limited, and it can be produced by esterification or transesterification reaction using the above monomer. Here, amorphous is one that does not have a definite melting point, and when crystalline polyester is used in the present invention, the amount of energy required for melting is large and the toner fixability cannot be improved, which is not preferable.

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

The acid value of the amorphous polyester is 3
It is preferably -50 (KOHmg / g), more preferably 10-30 (KOHmg / g). Three
When it is less than (KOHmg / g), the amorphous polyester as the shell material is hard to come out at the interface, and the storage stability is poor,
When it exceeds 50 (KOHmg / g), the polyester is apt to migrate to the aqueous phase and the production stability deteriorates. Here, the method for measuring the acid value is according to JIS K0070.

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

The resin used as the main component of the heat-meltable core material of the capsule toner having an outer shell made of amorphous polyester in the present invention is a thermoplastic resin such as polyester resin, polyester / polyamide resin, polyamide resin, vinyl resin and the like. Examples of the resin include a vinyl resin. The glass transition point derived from the thermoplastic resin which is the main component of such a heat-meltable core material is 10 to 50 ° C.
However, 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.

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

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

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

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

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

Two or more kinds of polymerization initiators may be mixed and used for the purpose of controlling the molecular weight and the molecular weight distribution of the polymer, 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.

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

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

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

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

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.
It is assumed to be μm. The thickness of the outer shell of the capsule toner is 0.01-1
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.

The above-mentioned capsule toner adhered to the electrostatic latent image formed on the photoconductor is transferred to the recording medium 6 by the transfer device 5b. As a transfer method, a corona transfer method of giving corona ions to the back side of the recording medium, a roller transfer method of forming a transfer electrolysis by applying a voltage to a back surface of the recording medium by applying a voltage applied to a conductive roller, and also transporting the recording medium The dielectric belt transfer method and the like are also applicable to the method of the present invention.

After the transfer step, a cleaning device 8 such as a cleaning web for removing a small amount of toner remaining on the photoconductor is installed facing the photoconductor 1. For example, as shown in FIG. 1 or 7, the fixing unit may employ a system in which the transferred toner on the recording medium is preheated before fixing and is fixed by pressure in the fixing unit. In this case, 4 heating heaters, 12 fixing rollers and 11
It is equipped with an endless film. Alternatively, a conventional heat roller system as shown in FIG. 8 may be used,
In this case, 14 heat rollers having 4 heating heaters inside and a fixing roller 12 are provided.

As shown in FIGS. 1 and 7, when the toner preheating method is used, the heating heater 4 can preheat the surface of the recording medium through the endless film in order to fix the toner. In addition, the recording medium is arranged near the upper part of the conveyance route of the recording medium. The heating heater 4 may be of any type as long as it is a device capable of heating the film surface up to 120 ° C. at most. Further, the endless film itself may be of a type that generates heat when energized, in which case a heating heater is unnecessary. As the heating element of the heating heater, for example, a heat source such as a hot plate, a quartz heater lamp, a flash, a heating belt, or a heating element can be used.

The endless film is not limited to a heat resistant film such as a fluororesin, a polyimide resin, a polyamide resin or a polyester resin, and the heating temperature can be set low,
Polypropylene film, polyethylene film, cellophane, etc. can also be used. At least 2 for endless film
It is stretched by one support roller 16.

The fixing roller 12 is a means for fixing the recording medium having the transferred toner image on the surface of the endless film by pressing, and is used as a pressure roller. In a normal fixing device, since fixing is performed at a high temperature (around 200 ° C.), it is necessary to use a heat-resistant silicone rubber having a heat resistance of 240 ° C. or higher for the fixing roller. However, in the present invention, since the fixing roller is in contact with the back surface of the recording medium and heat is not directly transmitted, and the temperature of the toner surface preheated by the heater 4 for heating is as low as 120 ° C. at most, it is transmitted to the fixing roller. The temperature to be applied is very low and heat resistance is not required. Therefore, the material is not particularly limited as long as it is an elastic body having a softening point of 120 ° C. or higher, and a usual inexpensive elastic material can be used. Further, the linear pressure is 4 in the fixing device of the present invention.
Since it is as small as less than kg / cm, it has a long useful life.

As shown in FIG. 8, when a heat roller is used for fixing, high heat resistance is conventionally required, so that the heat roller portion is made of an aluminum cylinder such as a Teflon coating. Although heat-resistant resins such as polyamide resin and polyamide-imide resin are used, since the fixing temperature is as low as 120 ° C. or less in the present invention, when the conventional heat-resistant film is used, the service life of the heat roller becomes long. Also, a film made of polyester resin, polypropylene resin, polyethylene resin or the like or a film not having heat resistance specifications such as cellophane can be used. The fixing roller 12 used when the heat roller is used is used as a pressure roller as in the case where the endless film is used, and its material is not particularly limited as long as it is an elastic body having a softening point of 120 ° C. or higher. Ordinary inexpensive elastic material can be used instead. Also in this case, since the linear pressure can be as small as less than 4 kg / cm, the service life of the fixing roller is extended.

The recording paper 6 which is a recording medium is conveyed along the surface of the endless film 11 by the conveyor belt 15 as shown in FIG. 7, and the heater 4 for heating the recording medium having the transferred toner image on the surface thereof. Is passed through while receiving the heat of the endless film in advance, and the toner image is fixed by being sandwiched between the fixing roller 12 and the supporting roller 16 via the endless film 11, and then a predetermined paper discharging unit (not shown). Is discharged to the outside of the device. Alternatively, as shown in FIG. 8, the heat roller 14 is conveyed by the conveyor belt 15.
Is fixed between the fixing roller 12 and the fixing roller 12 by heating and pressing,
The paper is ejected.

In the present invention, since the fixing temperature is low,
When a transparency sheet is used as a recording medium, it is characterized in that a film having a considerably low softening point of 100 to 200 ° C. can be used. That is,
As the film having such a softening point, a resin film such as a polyethylene film, a polypropylene film, a cellophane, a polycarbonate film, a polymethylmethacrylate film, and a polymethylpentene film can be mentioned, and a material which is inexpensive in comparison with a conventional product. Can be used.

In FIGS. 1, 7 and 8, reference numeral 13 denotes a radiator, and a honeycomb type radiator can be used in the method of the present invention in place of the conventionally used forced radiator such as an electric fan. .. The shape of the cross section is not particularly limited, such as a square, a rectangle, a parallelogram, and a regular hexagon. The radiator 13 is for radiating the heat generated in the fixing unit, and is installed so that the air flow flows from the lower side to the upper side in the vertical direction in order to easily radiate the heat. Further, the material may be a metal plate such as an aluminum plate or a stainless plate, or a plastic plate such as an acrylic plate or a bakelite plate. In the present invention, since the fixing temperature is low, it is possible to sufficiently radiate heat by providing the above-mentioned honeycomb radiator.

The photoconductor 1, the endless film 11, the heat roller 14, and the fixing roller 12 are rotated at a constant peripheral 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 described. Fig. 3 shows the charging process, Fig. 4
Shows an exposure step, FIG. 5 shows a developing step, FIG. 6 shows a transfer step, and FIGS. 7 and 8 show a fixing step.

In the charging step, as shown in FIG. 3, for example, a predetermined charge is uniformly applied to the surface of the photoconductor by the corona charger 7. Here, a photosensitive member sensitive to positive charges is taken as an example, and the photosensitive layer 1a is coated on the surface of the conductive support 1b to form the photosensitive member 1. A uniform charge is applied to the photosensitive layer 1a by the corona charger 7 to charge the surface of the photosensitive layer 1a with a positive polarity.

In the exposure step, as shown in FIG. 4, the surface of the photoconductor is irradiated with the light emitted from the exposure device 2, the electric charge leaks only in the exposed portion, and an electrostatic latent image is formed on the photosensitive layer 1a. ..

In the developing step, as shown in FIG. 5, the toner frictionally charged in the developing unit is carried through the rotary sleeve 3a, and adheres to the surface of the photosensitive member according to the charge on the surface of the photosensitive member to develop. In the developing process, there are regular development in which a toner having a polarity opposite to that of the charge is attached by a Coulomb force to a place having an electric charge and reversal development in which a toner is irradiated and is attached to a place where the electric charge is erased. In the developing process of the present invention, any of them can be used, but FIG. 5 shows an example of regular development.

In the transfer step, as shown in FIG. 6, the toner image on the surface of the photoreceptor is transferred to the recording medium 6 by the transfer corotron, the transfer roller and the like from the rear surface of the recording medium 6 such as recording paper. Although some untransferred toner remains on the surface of the photoconductor, it is removed by a cleaning device 8 such as a cleaning web provided facing the photoconductor as shown in FIG.

In the fixing step, when the endless film as shown in FIG. 7 is used, the toner image transferred to the surface of the recording medium 6 is contacted by the heating heater 4 via the transparent endless film 11. After being heated in advance, it is more strongly fixed to the recording medium 6 by being sandwiched between the fixing roller 12 and the supporting roller 16 via the endless film 11 and receiving pressure. When using a heat roller as shown in FIG. 8, the heat roller 14 and the fixing roller 1 are used.
By passing between the two, it is fixed on the recording medium 6 by receiving the same pressure as described above.

In order to melt the toner transferred to the recording medium such as recording paper, either in the case of using the endless film or in the case of using the heat roller, in the present invention, it is usually 60.
It is heated in the temperature range of 120 ° C. If the temperature is lower than 60 ° 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 problems with the conventional method arise.

The linear pressure at the time of fixing generally needs to be higher as the fixing temperature is lower. In the conventional method, it is usually 4 kg / kg.
A linear pressure of cm or more is required. However, according to the present invention, a sufficient fixing strength can be obtained with a linear pressure of usually 0.01 to 4 kg / cm, often less than 2 kg / cm, although the fixing temperature is 120 ° C. at most. In general, if the heat applied to the surface of the recording medium is too high, the recording paper curls, and if it is too low, the fixing of the toner becomes insufficient and it becomes difficult to store the record. ℃ ~ 1
Since it can be fixed at 20 ° C., such a problem is unlikely to occur.

On the other hand, when the developing and transferring steps are completed, the photoconductor 1 is neutralized by the static eliminating device 9 such as a static eliminating lamp to neutralize the remaining electric charges, and then returns to the charging step and is reused.

In the present invention, the performance of the heat dissociation type capsule toner used in the present invention or the capsule toner in which the outer grain is made of amorphous polyester is utilized in addition to the above-mentioned toner preheating method and heat roller method. Then, the transfer process and the fixing process can be performed simultaneously on the surface of the photoconductor. FIG. 9 shows a conceptual diagram of the image forming method in this case.

In this system, the recording medium is usually 60-160.
The preheated to ℃ is used, and the transfer and the fixing are simultaneously performed on the surface of the photoconductor by the heat retained on the recording medium by the preheating and the pressure from the pressure roller.

That is, this method is based on the preheating method of the recording medium. In FIG. 9, 4 is a heating heater, 5a is a pressure roller, and the heating heater 4 sends the preheated recording medium 6 to the pressure roller. As possible, it is provided in front of the contact between the photoconductor 1 and the pressure roller 5a. The heating heater 4 fixes the toner on the recording medium 6 such as recording paper.
Any device can be used as long as it is a device that heats the surface of the recording medium in contact with the toner in advance and can heat the surface of the recording medium up to 160 ° C. at most. For example, as the heating element of the heater 4 for heating, a heat source such as a hot plate, a quartz heater lamp, a flash, a heating belt, or a heating element can be used, and preferably a quartz heater lamp or a heating element can be used. .. The pressure roller 5a is a means for bringing the preheated recording medium 6 into pressure contact with the surface of the photoconductor, and in order to fix the recording medium 6 at a high temperature in a normal fixing device, it is necessary to use heat resistant silicone rubber or the like. In the invention, since the preheated recording medium is in contact with the back surface of the preheated recording medium and the preheated heat is not directly transmitted, particularly high heat resistance is not required. Therefore, the material is not particularly limited as long as it is an elastic body having a heat resistance of at most 150 ° C. or higher, and an ordinary inexpensive elastic material such as heat-resistant polyurethane or acryl-based material,
Nitrile-based, non-conjugated diene terpolymer such as EPDM, etc. can be used. The linear pressure applied by the pressure roller is usually 0.01 to 4.0 kg / cm, preferably 0.
Since it is as small as 05 to 2 kg / cm, the service life is extended. In the present invention, a belt may be used as a similar means instead of the pressure roller.

In the transfer / fixing process, as shown in FIG. 10, the toner image developed by the toner adhering to the surface of the photosensitive member is conveyed and simultaneously heated by the heater 4 for heating so as to be synchronized with the starting end of the toner image. The recording medium 6 such as the recorded recording paper is pressed against the surface of the photoconductor by pressure from the back surface of the recording medium by the pressure roller 5a, the toner is transferred to the recording medium 6, and at the same time, a toner image is formed on the surface of the recording medium. It is fixed. That is, when the toner adhering to the latent image on the surface of the photoconductor is pressed against the recording medium, the heat of the recording medium changes the structure of the capsule toner shell, and at the same time the core material is released by the pressure from the pressure roller. Establish. If the heat applied to the surface of the recording medium by the heating heater 4 is too high, the recording paper curls, and if it is too low, the fixing of the toner becomes insufficient and it becomes difficult to store the record. The temperature is 60 ° C to 160 ° C, preferably 60 ° C to 120 ° C. The linear pressure in this case is usually 0.01 to 4 kg / cm, as in the case of the toner preheating system or the heat roller system, and sufficient fixing strength can be obtained.

In this transfer / fixing system, almost all of the toner is transferred to the recording medium, so that a recovery toner device is not required. Although a small amount of toner may remain on the entire surface of the photoconductor after being transferred to the recording medium 6, this may be rubbed off by pressure contact with the photoconductor such as a cleaning web provided facing the photoconductor. Yes, the photoreceptor can be used repeatedly.

On the other hand, when the transfer and fixing steps of the photoconductor 1 are completed, the static elimination lamp 9 arranged so as to face the photoconductor 1 is removed.
The residual charge on the photoconductor is neutralized by this, and it returns to the charging step and is reused.

The present invention is not limited to the above-mentioned embodiment, and the specifications such as the type of each device and the process can be changed based on the principle of the present invention.

[0072]

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

Production Example 1 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, and the mixture was put into an attritor (manufactured by Mitsui Miike Kakoki) 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 of 4% by weight of tricalcium phosphate prepared 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 (manufactured by Tokushu Kika Kogyo Co., Ltd.). 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.
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 continuing stirring under nitrogen, the temperature was raised to 80 ° C. and reacted 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. under reduced pressure at 20 mmHg for 12 hours 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. This is designated as Toner 1.

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

The degree of polymerization was traced from the softening point according to ATSM E28-67, and the reaction was terminated when the softening point reached 110 ° C. The glass transition point of the obtained resin was measured by a differential scanning calorimeter (manufactured by Seiko Denshi Kogyo Co., Ltd.) and found to be 65 ° C. In addition, the softening point and the acid value were measured and 110 ° C and 18 KOHmg /
It was g. The acid value was measured by a method according to JIS K0070.

20 parts by weight of the resin obtained as described above was added to 69.0 parts by weight of styrene, 31.0 parts by weight of 2-ethylhexyl acrylate, 0.9 parts by weight of divinylbenzene, 7.0 parts by weight of carbon black "# 44" (manufactured by Mitsubishi Kasei). Part, 2,2 '
-Azobisisobutyronitrile (3.5 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 to a 2 liter glass separable flask in an amount of 30% by weight in 800 g of an aqueous colloidal solution of 4% by weight of tricalcium phosphate, and TK homomixer (made by Tokushu Kika Kogyo Co., Ltd.) Was emulsified and dispersed at 5 ° C for 5 minutes at a rotation speed of 12000 rpm.

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

To 100 parts by weight of this capsule toner, 0.4 parts by weight of hydrophobic silica fine powder "Aerosil R-972" (manufactured by Nippon Aerosil Co., Ltd.) was added and mixed to obtain a capsule toner of the present invention. The glass transition point derived from the resin in the core material is 30.6
C., and the softening point of Toner 1 was 125.5.degree. This is designated as toner 2.

Production Example of Reference Toner 100 parts by weight of a polyester resin (bisphenol type polyester resin, softening point 135 ° C., Tg: 65 ° C.) is added to 7 parts by weight of carbon black (MA8 manufactured by Mitsubishi Kasei Co., Ltd.) and polypropylene wax (SANYO). Kasei Co., Ltd .: Viscole 660P) 3 parts by weight and charge control agent (Hodogaya Chemical Co., Ltd .: Eisenspiron Black TRH) 2 parts by weight are mixed and then kneaded with a pressure kneader, cooled, and then finely pulverized. With a classifier, a toner having a particle size distribution of 5 to 25 μm and an average particle size of 10 μm was manufactured. 5 for 1 kg of toner obtained
g colloidal silica (Nippon Aerosil Co., Ltd .: R97
2) was externally added to obtain a surface-treated reference toner.

Test Example 1 Toner 5 manufactured in the above-mentioned Capsule Toner Manufacturing Example 1
0 g was mixed with 1 kg of a commercially available ferrite carrier with a V-type blender to obtain a developer 1. The developer 1 thus obtained was put in a commercially available copying machine to perform image formation without fixing, and the fixing device (endless film made of polyethylene terephthalate, fixing roller diameter: 20 mmφ, linear pressure in the present invention shown in FIG. 7 was used. : 0.3 kg / cm, Ushio Electric's heating heater)
Using, the heating temperature was varied at a linear velocity of 20 mm / sec and the fixing property and the non-offset area were measured. The recording medium is a polyethylene film having a softening point of 120 ° C. (Okura Industry Co., Ltd.)
Manufactured by the company) was used. As a result, the surface temperature on the side of the transparency sheet of the endless film heated by the heater was sufficiently fixed at 98 ° C, and the toner was not offset to the endless film from 80 ° C to 140 ° C.

On the other hand, the toner obtained in the above-mentioned production example of the reference toner was mixed with a commercially available ferrite carrier to prepare a developer 3, and the same image was produced by a commercially available copying machine in the same manner as described above. After that, the fixability and the non-offset area were measured using the fixing device of the present invention. As a result, the surface temperature of the endless film on the transparency sheet side is 1
It was fixed at 33 ° C and did not offset from 110 ° C to 140 ° C.

Test Example 2 The developer 1 obtained in Test Example 1 was placed in a commercially available copying machine to perform image formation without fixing, and a heat roller type fixing device (heat roller diameter: 20 mmφ) shown in FIG. , Linear pressure: 0.
3kg / cm, heat roller with aluminum surface 20μm Teflon processed, fixing roller (pressure roller)
Is a heat resistant silicone rubber roll), and the linear velocity is 2
The fixing temperature and the non-offset area were measured by changing the heating temperature at 0 mm / sec. The same recording medium as in Test Example 1 was used. As a result, the toner of the present invention was sufficiently fixed on the transparency sheet at the heat roller surface temperature of 95 ° C, and the non-offset area was 70 to 200 ° C.

On the other hand, using the developer 3 obtained in Test Example 1, the same image was formed on a commercially available copying machine in the same manner as described above, and then the same fixing device was used to fix the fixability and non-offset areas. It was measured. As a result, the reference toner was fixed on the transparency sheet at 130 ° C, and the non-offset area was 110 to 200 ° C.

Test Example 3 Toner 5 produced in Production Example 2 of the above-mentioned capsule toner
0 g was mixed with 1 kg of a commercially available ferrite carrier with a V-type blender to obtain a developer 2. The developer 2 thus obtained was copied using an apparatus shown in FIG. 9, which was obtained by modifying a commercially available copying machine. The same recording medium as in Test Example 1 was used. That is,
A heat-resistant organic photoconductor was used as the photoconductor, and a quartz heater lamp as a heater for heating was placed 3.0 cm away from the contact point between the photoconductor and the pressure roller, and was placed substantially parallel to the upper part of the transfer route of the transparency sheet. Further, the preheating temperature was made variable, and the conveying speed was made variable so that the temperature on the surface of the transparency sheet could be preheated to 60 to 160 ° C. The pressure roller used for transfer / fixing was a silicone rubber roller having a diameter of 30 mmφ, and the linear pressure was 0.5 kg / cm and the peripheral speed was 40 mm / sec.

As a result, the minimum fixing temperature on the surface of the transparency sheet is 95 ° C, which is 80 ° C to 140 ° C.
Up to now, no fusion of the toner on the surface of the photoconductor was observed. On the other hand, using the developer 3 obtained in Test Example 1, copying was performed in the same manner using the same recording medium as described above and an apparatus obtained by modifying a commercially available copying machine. As a result, the minimum fixing temperature was 135 ° C.

Here, the minimum fixing temperature means that the bottom surface is 15 mm × 7.
A load of 500 g was put on a 5 mm sand eraser, and the image fixed through the fixing device was rubbed 5 times back and forth, and before rubbing, the optical reflection density was measured with a reflection densitometer of Macbeth Co., and the fixing ratio was defined as follows. Is the temperature of the fixing roller when exceeds 70%. Fixing rate (%) = (image density after rubbing / image density before rubbing) x 100

Test Example 4 The apparatus used in Test Examples 1 to 3 had a softening point of 1 as a recording medium.
A 3000-sheet continuous copying test was performed using a polypropylene film (manufactured by Sankyo Polyethylene Co., Ltd.) at 51 ° C., the developer 1 obtained in Test Example 1 and the developer 2 obtained in Test Example 3 as developers. The apparatus in Test Example 1 had a linear velocity of 20 mm / sec and the preheating temperature was 120 ° C., and the apparatus in Test Example 2 had a linear velocity of 20 mm.
The heating temperature of the heat roller was adjusted to 110 ° C. and the preheating temperature was adjusted to 120 ° C. and the peripheral speed of the pressure roller used for transfer / fixing was adjusted to 40 mm / sec in mm / sec. As a result, the fixing was good in any of the devices, and no curling or jamming of the transparency sheet was observed.

On the other hand, the developer 3 obtained in Test Example 1 was used to perform continuous copying from several tens to 100 sheets in the same manner in each apparatus. As a result, in the apparatus of Test Example 1, the toner adhered to the surface of the endless film and the image quality contamination became noticeable on 20 sheets. Also, the fixed image was easily peeled off by rubbing it with paper. Further, in the apparatus of Test Example 2, the image quality was significantly deteriorated from the first image and cold offset was also generated. Further, in the apparatus of Test Example 3, the photoreceptor was contaminated by the toner and the image deterioration gradually progressed. Also, the fixed image was easily peeled off by rubbing it with paper.

From these test examples, the transparency forming sheet was used as the recording medium by using the image forming method of the present invention using the heat dissociation type capsule toner or the capsule toner in which the outer grain is the amorphous polyester. In that case, a film having a low softening point can be used, and a significant decrease in the minimum fixing temperature was observed. Moreover, the curl of the transparency sheet or the clogging was not recognized.

[0090]

According to the image forming method of the present invention, 120
Since fixing can be performed at a fixing temperature of ℃ or less, especially when using a transparency sheet, a recording medium having a low softening point can be used, and an inexpensive material can be used. Further, since the fixing temperature and the linear pressure can be reduced in this way, curling of the recording medium is less likely to occur, and paper clogging is less likely to occur, resulting in less maintenance.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of an example of an image forming method (toner preheating method) of the present invention.

FIG. 2 is 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 process 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 where a heater for heating 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.

FIG. 9 is a conceptual diagram of an example of an image forming method (recording medium preheating method) of the present invention.

FIG. 10 is a conceptual diagram showing a transfer / fixing process in a case where the recording medium is preheated in the image forming method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoconductor 1a Photosensitive layer 1b Conductive support 2 Exposure device 3 Developing device 3a Rotating sleeve 4 Heater 5a Pressure roller 5b Transfer device 6 Recording medium 7 Charging device 8 Cleaning device 8a Collecting toner box 9 Electrifying device 10 Toner 11 Endless Film 12 Fixing Roller 13 Radiator 14 Heat Roller 15 Conveyor Belt 16 Support Roller

Claims (15)

[Claims] 1. A charging step of charging a photoreceptor, an exposing step of exposing the photoreceptor, and a developing step of forming a toner image by attaching toner to an electrostatic latent image formed on the photoreceptor. In the image forming method, which comprises 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 a thermal dissociation type capsule toner or an external grain is amorphous. It is a capsule toner made of high quality polyester and has a softening point of 100 to 200.
An image forming method, characterized in that the fixing step is carried out under the temperature condition of 60 to 120 ° C. by using a recording medium having a temperature of 60 ° C. 2. The image forming method according to claim 1, wherein the recording medium is selected from the group consisting of polyethylene film, polypropylene film, cellophane, polycarbonate film, polymethylmethacrylate film, and polymethylpentene film. 3. The linear pressure in the fixing step is 0.01 to 4 k.
The image forming method according to claim 1, wherein the image forming method is g / cm. 4. The image forming method according to claim 1, wherein the heat source of the fixing device is a heating element via an endless film. 5. The image forming method according to claim 1, wherein the heat source of the fixing device is a heat roller. 6. The image forming method according to claim 1, wherein the transfer step and the fixing step are simultaneously performed on the surface of the photoconductor using a preheated recording medium. 7. A heat dissociable capsule toner is 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, and the main component of the outer shell is (1) 0 to 30 mol% of a monovalent isocyanate compound and / or isothiocyanate compound based on 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 image forming method according to claim 1, wherein the above-mentioned is a bond exhibiting thermal dissociation property. 8. The image forming method according to claim 7, wherein the bond exhibiting thermal dissociation is a bond derived from a reaction of a phenolic hydroxyl group and / or a thiol group with an isocyanate group and / or an isothiocyanate group. 9. The image forming method according to claim 7, wherein in the heat dissociative capsule toner, 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. .. 10. The softening point of the heat dissociative capsule toner is
The image forming method according to claim 7, which has a temperature of 80 to 150 ° C. 11. A toner is composed of a thermoplastic core material containing at least a thermoplastic resin and a colorant, and an outer shell provided so as to cover the surface of the core material, and the outer shell is made of amorphous polyester. The image forming method according to claim 1, wherein 12. The image forming method according to claim 11, wherein the amorphous polyester has a glass transition point of 50 to 80 ° C. 13. The acid value of the amorphous polyester is 3 to 5
The image forming method according to claim 11, which is 0 (KOHmg / g). 14. The amorphous polyester is at least one selected from the group consisting of a divalent alcohol monomer and a trivalent or higher polyhydric alcohol monomer, a divalent carboxylic acid monomer and a trivalent monomer. The image forming method according to claim 11, which is obtained by polycondensation of at least one kind selected from the group consisting of the above polyvalent carboxylic acid monomers. 15. The glass transition point derived from a thermoplastic resin, which is a main component of a heat-fusible core material, in a capsule toner whose outer grain is made of amorphous polyester is from 10 to 50 ° C. Image forming method.