JPH06161141A - Image forming method - Google Patents

Abstract

(57) [Summary] [Structure] A step of forming an electrostatic latent image, a developing step of adhering toner to the latent image to form a toner image, and the formed toner image is simultaneously transferred to a preheated recording medium. An image forming method having a fixing step, wherein the toner comprises 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, An image forming method, wherein the outer shell is a capsule toner made of amorphous polyester. According to the present invention, the toner image formed in the developing process is simultaneously transferred and fixed to the recording medium whose surface is heated by preheating, so that the transfer and fixing process is greatly simplified. . Further, since the fixing is performed at a low temperature, the heat dissipation device can be greatly simplified, and the image forming apparatus can be downsized.

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, various methods such as electrophotography and electrostatic recording have been used to form an image in a copying machine or a laser beam printer. FIG. 3 shows a conceptual diagram of an image forming method using a conventional electrophotographic method. In the conventional method, an electrostatic latent image formed on a photoconductor by an optical means is first developed in a developing process and then transferred. The image is formed by being transferred onto a recording medium such as recording paper in a process, and then generally fixed by heat and pressure in a fixing process. Since the photosensitive member is repeatedly used, a cleaning device is installed to clean the residual toner after transfer as the photosensitive member rotates.

However, in the conventional image forming method using electrophotography, the process from forming an electrostatic latent image to fixing it on a recording medium is long and the apparatus is not only complicated but also large in size. Since the transfer efficiency of the toner in the process is poor, there are problems such as the waste of the collected toner collected by cleaning the remaining toner and the contamination due to the scattering of the toner inside and outside the apparatus.

Therefore, a method for simultaneously performing transfer and fixing is provided (US Pat. No. 4,448,872). In this method, the toner image developed on the dielectric drum is transferred and fixed at the same time on the recording medium by pressure, so that the device can be certainly simplified,
Since only pressure can be applied during fixing, the fixability is poor,
The problem remains that the transfer efficiency is not improved. Toner fixing is generally performed at a high temperature because the melting temperature of the toner is high, and thus a device with high thermal efficiency is required. The fixing step usually exists independently, and in reality, fixing is performed at a high temperature of about 200 ° C. Therefore, a heat resistant member using expensive heat resistant resin, heat resistant rubber or the like is required around the fixing device. Further, if fixing is performed at a high temperature in this manner, problems such as curling and jamming of the paper are likely to occur, and problems occur. Therefore, in consideration of heat dissipation from the viewpoint of equipment, an optimum heat dissipation device is required. Is the reality.

On the other hand, as a method of solving such a problem, a toner image is formed by adhering toner on a transfer film, a portion of which moves intimately on the photosensitive drum, and the toner image is formed at a position apart from the photosensitive drum. The transfer film and recording paper are sandwiched between a pressure roll and a heat roll to transfer
An image forming method has been proposed in which the fixing step is simultaneously performed (Japanese Patent Laid-Open No. 2-197884). However, according to this method, the transfer film becomes complicated and the size becomes larger. Further, by passing through the transfer film, the exposure amount is reduced, the lines of electric force corresponding to the electrostatic latent image formed on the photosensitive drum are weakened, the toner suction force is reduced, and the resolution during development is deteriorated. The problem is pointed out.

On the other hand, in the electrostatic recording system, a signal voltage is applied from a recording needle onto an electrostatic recording sheet such as recording paper to form an electrostatic latent image, and then development is performed using a developing device such as a magnetic brush, In this method, the electrostatic latent image is transferred and fixed by means such as heat and pressure. However, the toner adheres to extra areas on the recording medium such as recording paper during development.
So-called scumming occurs, and when a voltage is directly applied to the recording paper by a recording needle, foreign matter such as paper dust adheres to the recording needle, which makes it difficult to obtain a normal image.
There is a problem in obtaining stable high-quality images continuously.

As a means for improving such problems,
JP-A-55-84696 or JP-A-3-1370
As described in Japanese Patent Laid-Open Publication No. 1-1990, a magnetic film or an insulating film is used, toner is evenly applied on the surface of the film, and then a heat pulse is supplied from the back surface of the film by a thermal head in accordance with a signal to obtain the toner. There is known a method of fusing a sheet of paper and forming an image on the surface of the recording paper which faces the sheet.
However, in this method, the toner cannot be applied uniformly and the image becomes uneven in stripes, and there is a concern that a part of the applied toner layer may agglomerate due to heat. There is a high possibility that it will behave as a foreign substance. Further, it has been pointed out that there is a problem that toner adheres to an extra portion on a recording medium such as a recording paper at the time of fixing, that is, so-called scumming easily occurs.

As described above, various problems have been pointed out in both the electrophotographic system and the electrostatic recording system, and from these viewpoints, development of a new system and a toner adapted thereto is expected. In order to meet such expectations, the present applicant has developed a capsule toner whose outer grain is made of amorphous polyester and has already applied for a patent (Japanese Patent Application No. 4-
259088). This capsulated toner has excellent offset resistance and blocking resistance in the heat and pressure fixing method, can be fixed at a low temperature, and can form a clear image without fog a number of times stably. Therefore, it has been demanded to develop an image forming method suitable for using the toner. An object of the present invention is to solve the above-mentioned problems and to provide an image forming method particularly suitable for the case of using a capsule toner whose outer grain is made of amorphous polyester.

[0009]

The summary of the present invention is as follows.
(1) It has a step of forming an electrostatic latent image, a developing step of adhering toner to the latent image to form a toner image, and a step of simultaneously transferring and fixing the formed toner image to a preheated recording medium. An image forming method, wherein the toner comprises a thermoplastic core material containing at least a thermoplastic resin and a colorant,
(2) An image forming method, comprising an outer shell provided so as to cover the surface of the core material, the outer shell being a capsule toner made of amorphous polyester. The preheating temperature to the recording medium is 50 ℃ or more 16
The image forming method according to (1) above, which is 0 ° C. or lower, (3)
The image forming method according to (1) or (2) above, wherein the amorphous polyester has a glass transition point of 50 to 80 ° C.
The acid value of the amorphous polyester is 3 to 50 (KOHmg /
The image forming method according to (1) or (2), which is g),
(5) The amorphous polyester is obtained by polycondensation of one or more alcohol monomers and one or more carboxylic acid monomers, and contains at least a trihydric or higher polyhydric alcohol monomer and And / or the image forming method according to the above (1) or (2), which is obtained by polycondensation using a monomer containing a polyvalent carboxylic acid monomer having a valence of 3 or more; , The glass transition point derived from the thermoplastic resin which is the main component of the heat-fusible core material is 10 to 5
The image forming method according to (1) or (2) above, which is 0 ° C.
And (7) The image according to (1) or (2) above, wherein the capsule toner having an outer shell made of amorphous polyester is obtained by coating the surface of a core material with the amorphous polyester by an in situ polymerization method. It relates to a forming method.

[0010]

According to the present invention, the toner image formed in the developing step is simultaneously transferred and fixed to the recording medium whose surface is heated by preheating. Therefore, the transfer / fixing process is greatly simplified, and since the low-temperature fixing is performed, the heat dissipation device can be greatly simplified, and the image forming apparatus can be downsized.

[0011]

Embodiments of the present invention will now be described in detail with reference to the drawings. In the image forming method of the present invention, a recording medium is preheated, and the toner image is transferred and fixed at the same time by using the preheated recording medium. Therefore, the image forming method of the present invention can be used in any method as long as it is a recording method of transferring and fixing to a recording medium, and is not particularly limited. For example, the image forming method of the present invention can be applied to electrophotographic and electrostatic recording methods. In addition, it can be applied to magnetography, ion deposition method, and the like.

FIG. 1 is a conceptual diagram when the image forming method of the present invention is applied to an electrophotographic system as an example. Reference numeral 1 is a photosensitive drum such as amorphous silicon or an organic photosensitive member having a photosensitive layer provided on a conductive support. Selenium-based, silicon-based, organic-based, etc. have been put into practical use for the photoconductor, and any of these may be used, but as described below, the photoconductor receives considerable heat from the preheated recording medium, the silicon photoconductor is used. An organic photoreceptor in consideration of the body or heat resistance is preferable. Further, since transfer / fixing is performed on the surface of the photoconductor, it is preferable to use a photoconductor having both robustness and abrasion resistance.

Reference numeral 7 denotes a charging device, which is provided so as to face the photoconductor. The charging means is not particularly limited and, for example, a corona charger, a brush 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 surface of the photoconductor. 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 a developing device installed facing the photoconductor 1 to visualize 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.

Reference numeral 4 is a heater for heating and 5a is a pressure roller. The heater for heating 4 is provided in front of the contact between the photosensitive member 1 and the pressure roller 5a so that the preheated recording medium can be fed to the pressure roller. Also, in order to prevent a decrease in the surface temperature of the paper, the distance between the photoconductor and the heater for heating is preferably as small as possible, but it is preferable to install the photoconductor at a distance that does not affect the photoconductor and heat deterioration. . The heating heater 4 is a device that preheats the surface of the recording medium such as recording paper that comes into contact with the toner in order to fix the toner, and any type of device can be used as long as it can heat the recording medium surface up to 160 ° C. It doesn't matter. For example, as the heating element of the heating heater, a hot plate, a quartz heater lamp, a flash, a heating belt,
A heat source such as a heating element can be used, and a quartz heater lamp or a heating element is preferable. The pressure roller 5a is a means for bringing the preheated recording medium into pressure contact with the surface of the photoconductor, and it is necessary to use heat resistant silicone rubber or the like in order to fix the recording medium at a high temperature in an ordinary fixing device. Then contact the back of the preheated recording medium,
Particularly high heat resistance is not required because the preheated heat is not directly transmitted. Therefore, as long as it is an elastic body having a heat resistance of 150 ° C. or higher, its material is not particularly limited, and a usual inexpensive elastic material can be used. The linear pressure applied by the pressure roller is usually 0.01 to 4 kg / c.
m, preferably 0.1 to 1 kg / cm, which is small (4 kg / cm or more in the prior art), so that the service life is extended. In the present invention, a belt may be used as a similar means instead of the pressure roller.

After the transfer / fixing process, 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.
The photoconductor 1 and the pressure roller 5a are rotated at a constant peripheral speed in the direction shown in FIG. 1 by a predetermined driving means (not shown).
On the other hand, the recording paper 6 which is a recording medium is conveyed as shown in FIG. 1, passes through the pressure roller 5a, and is then ejected outside the apparatus by the paper ejection means.

Next, FIG. 2 shows a conceptual diagram when the image forming method of the present invention is applied to an electrostatic recording system as an example. Reference numeral 21 is an application device, 23 is a developing device, 27 is an insulating endless film belt, 29 is toner, 24 is a heater for heating, and 25 is a pressure roller. The application device 21 is arranged on the surface of the insulating endless film belt 27 so as to face each other, and applies a pulse voltage while driving the insulating endless film belt 27 and the pin electrodes to a large number of pin electrodes provided side by side. It is a means for causing an electric discharge between the insulating endless film belt and the electric charge representing a character or a symbol on the insulating endless film belt. The obtained electrostatic latent image is developed with the toner 29 in the developing device 23. The insulative endless film belt 27 is made of a fluororesin-based, polyester-based, polyimide-based, polyamide-based heat-resistant film of 5 to 20 μm and a film such as polypropylene film, polyethylene film, cellophane, or a conductive layer coated with a dielectric. Used. The insulating endless film belt 27 is stretched around a support roller 30.

As in the case of the electrophotographic method, the heater 24 for heating heats the preheated recording medium 26 to the pressure roller 25.
It is provided in front of the contact between the insulating endless film belt 27 and the pressure roller 25 so that the sheet can be fed to. The heating heater 24 is a device that preheats the surface of the recording medium that comes into contact with the toner in order to fix the toner. In particular,
Any apparatus capable of heating the surface of the recording medium up to 160 ° C. may be used, and examples thereof include those similar to the case of the electrophotographic method. The pressure roller 25 is a means for pressing the preheated recording medium onto the surface of the insulative endless film belt 27, but it has a low linear pressure as in the case of the electrophotographic method, and the directly preheated heat is applied. Is not transmitted, no particular heat resistance is required. A belt may be used as a similar means instead of the pressure roller.

After the transfer and fixing onto the recording paper, a cleaning web 28 for cooling the insulating endless film belt 27 and for removing a slight amount of residual toner in some cases is installed facing the insulating endless film belt 27. To remove heat and residual toner. Further, residual charges are removed by a static eliminator 22 such as a conductive brush or a conductive roll, and the insulating endless film belt 27 is returned to the initial state and reused.

The toner used in the image forming method of the present invention comprises 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. The outer shell is a capsule toner made of amorphous polyester. Among these, since the transfer step does not use the Coulomb force due to charging, not only the insulating capsule toner but also the conductive capsule toner can be used. Such a capsule toner is excellent in offset resistance and blocking resistance in the heat and pressure fixing method, can be fixed at a low temperature (usually 50 to 120 ° C.), and can stably form a clear image without fog many times. Have.

The toner used in the present invention is a capsule toner whose outer grain is made of amorphous polyester as described above. This amorphous polyester is usually obtained by polycondensation of one or more alcohol monomers (divalent, trivalent or more) and one or more carboxylic acid monomers (divalent, trivalent or more). And is obtained by polycondensation using a monomer containing at least a trihydric or higher polyhydric alcohol monomer and / or a trivalent or higher polyhydric carboxylic acid monomer (Japanese Patent Application No. Hei 10-242242). 4-259088).

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

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

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

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

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

The acid value of the amorphous polyester is 3
It is preferably -50 (KOHmg / g), more preferably 10-30 (KOHmg / g). Three
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 of which the outer grain is made of amorphous polyester used in the present invention is produced by a known method such as an in situ 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.

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

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

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

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

Further, as the polymerization initiator used 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-based polymerization initiators such as oxides.

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

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

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

The positively chargeable charge control agent is not particularly limited, and examples thereof include nigrosine dye "Nigrosine base EX", "oil black BS", "oil black SO", "bontron N-01", and "bontron". N-07 "," Bontron N-11 "(above, manufactured by Orient Chemical Co., Ltd.), triphenylmethane dye containing a tertiary amine as a side chain, quaternary ammonium salt compound, for example," Bontron P-51 "( Orient Chemical Co., Ltd.),
Cetyl trimethyl ammonium bromide, "COPY CHARG
Examples thereof include EPX VP435 "(manufactured by Hoechst) and the like, and polyamine resins such as" AFP-B "(manufactured by Orient Chemical Co.) and imidazole derivatives. The above charge control agent is contained in the core material in an amount of 0.1 to 8.0% by weight, preferably 0.2 to 5.0% by weight. In the core material, if necessary, for the purpose of improving offset resistance in heat and pressure fixing, for example, polyolefin, fatty acid metal salt, fatty acid ester, partially saponified fatty acid ester, higher fatty acid, higher alcohol, paraffin wax, amide series Any one or more kinds of offset preventing agents such as wax, polyhydric alcohol ester, silicon varnish, aliphatic fluorocarbon, and silicone oil may be contained.

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

When a magnetic capsule toner is used in the present invention, magnetic particles may be added instead of carbon black or the like as a core material constituting material to obtain a magnetic capsule toner. As the magnetic particles, for example, ferrite, magnetite and other iron, cobalt, nickel and other ferromagnets or alloys showing ferromagnetism, compounds containing these elements, or containing no ferromagnetism elements, an appropriate heat treatment is applied. Examples thereof include alloys that exhibit ferromagnetism, such as manganese-copper-aluminum, manganese-copper-tin, and other types of alloys called Heusler alloys containing manganese and copper, or chromium dioxide.
These magnetic materials are uniformly dispersed in the core material in the form of fine powder having an average particle size of 0.1 to 1 μm. The content is 20 to 70 parts by weight, and preferably 100 parts by weight of the capsule toner.
30 to 70 parts by weight. When the fine magnetic powder is added to the toner to make it a magnetic toner, it may be treated in the same manner as in the case of the colorant, but as it is, it has a low affinity for organic materials such as core materials and monomers. Therefore, when the magnetic fine powder is used together with a so-called coupling agent such as a titanium coupling agent, a silane coupling agent, and lecithin or after being treated with the coupling agent, the magnetic fine powder can be uniformly dispersed.

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

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

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

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

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

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

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

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

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

Examples of the cleaning property improver include metal salts of higher fatty acids typified by zinc stearate and fine particles of fluorine-based high molecular weight particles. Further additives for adjusting the developability, for example, methacrylic acid methyl ester,
Fine particles of a polymer such as methacrylic acid butyl ester may be used. Further, a small amount of carbon black may be used for toning and resistance adjustment. As the carbon black, conventionally known ones, for example, various ones such as furnace black, channel black and acetylene black can be used.

The capsule toner of the present invention is used alone as a developer when it contains magnetic fine powder, and when it does not contain magnetic fine powder, it is mixed with a carrier to form a two-component composition. A system developer can be prepared and used. The carrier is not particularly limited, but iron powder, ferrite, glass beads or the like, or those coated with a resin thereof is used, and the mixing ratio of the toner to the carrier is 0.5 to 10% by weight. The carrier has a particle size of 30 to 500 μm.

Next, each step of the image forming method of the present invention having the above structure will be described. First, as an electrophotographic method, FIG. 4 shows a charging step, FIG. 5 shows an exposing step, FIG. 6 shows a developing step, and FIG. 7 shows a transfer / fixing step. In the charging step, as shown in FIG. 4, 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 high voltage 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. 5, the surface of the photoconductor is irradiated with the light emitted from the exposure device 2, and charges are leaked only in the exposed portion to form an electrostatic latent image on the photosensitive layer 1a. .

In the developing step, as shown in FIG. 6, the toner frictionally charged in the developing device is carried through the rotary sleeve 3a, and adheres to the surface of the photoconductor in accordance with the charge on the surface of the photoconductor to develop the toner. In the developing process, there are normal development in which a toner having a polarity opposite to that of the charge is attached by a Coulomb force where there is a charge, and reversal development in which a toner is attached where light is irradiated and the charge is erased. In the developing process of the present invention, any of these can be used, but FIG. 6 shows an example of regular development.

In the transfer / fixing step, as shown in FIG. 7, the toner image developed by the toner adhering to the latent image on the surface of the photosensitive member is conveyed, and at the same time, the heater for heating is synchronized so as to be synchronized with the starting end of the toner image. A recording medium 6 such as a recording paper heated by 4 is pressed against the surface of the photoconductor by receiving pressure from the back surface of the recording medium by the pressure roller 5a,
At the same time that the toner is transferred to the recording medium 6, the toner image is fixed on the surface of the recording medium. If the heat given 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 recording. Is usually 5
The temperature is 0 ° C to 160 ° C, preferably 50 ° C to 120 ° C.

In the present invention, since almost all of the toner is transferred to the recording medium, a device for collecting toner is not necessary. Although a small amount of toner may remain on the surface of the photoconductor 1 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. The photoconductor can be used repeatedly. On the other hand, when the transfer / fixing process of the photoconductor 1 is completed, the electric charge remaining on the photoconductor is neutralized by the static elimination lamp 9 disposed so as to face the photoconductor 1, and the process returns to the charging process and is reused. It

Next, in the case of the electrostatic recording method, as shown in FIG.
As shown in FIG. 1, first, the application device 21 supplies electric charges representing characters or symbols to the insulating endless film belt 27 to form an electrostatic latent image on the insulating endless film belt 27. A toner image is formed by adhering the toner 29 in the developing device to this latent image. The transfer / fixing process is performed by passing the recording medium 26 preheated by the heater 24 between the pressure roller 25 and the insulating endless film belt 27, as in the case of the electrophotographic method. That is, as shown in FIG. 2, the toner image developed by the toner adhered on the surface of the insulating endless film belt is insulated at a constant peripheral speed in the direction shown in the drawing by a predetermined driving means (not shown). A recording medium 26, such as recording paper, which is conveyed by the rotation of the endless type endless film belt and is heated by the heating heater 24 at the same time so as to be synchronized with the starting end of the toner image from the back surface of the recording medium 26 by the pressure roller 25. By receiving the pressure, the insulating endless film belt 27 is pressed against the surface, the toner is transferred to the recording medium 26, and the image is fixed at the same time. If the heat applied to the surface of the recording medium by the heating heater 24 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 recording. Is the same as in the case of the electrophotographic method. When the transfer / fixing process is completed, the paper is ejected to the outside of the apparatus by the paper ejecting means. Incidentally, the present invention is not limited to the above-mentioned embodiments, and the types of each device based on the principle of the present invention,
It is possible to change specifications such as processes.

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

The degree of polymerization was traced from the softening point according to 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. Also, the softening point and the acid value were measured, and were 110 ° C. and 18 KOHmg /
It was g. The acid value was measured by a method according to JIS K0070.

69.0 parts by weight of styrene, 31.0 parts by weight of 2-ethylhexyl acrylate, 0.9 parts by weight of divinylbenzene, 7.0 parts by weight of carbon black "# 44" (manufactured by Mitsubishi Kasei), and 20 parts by weight of the resin obtained above, 3.5 parts by weight of 2,2′-azobisisobutyronitrile 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 containing 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 4-port glass lid was attached, a reflux cooling tube, a thermometer, a nitrogen introduction tube, and a stainless steel stirring rod were attached and the lid was placed in an electric heating mantle heater. While continuing stirring under nitrogen, the temperature was raised to 85 ° C. and the reaction was performed for 10 hours. After cooling, dissolve the dispersion medium with 10% aqueous hydrochloric acid, filter, wash with water, dry under reduced pressure at 20 mmHg for 12 hours at 45 ° C, classify with a wind classifier, and remove the outer shell with an average particle size of 8 μm. A capsule toner which is a crystalline polyester was obtained.

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

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

The degree of polymerization was traced from the softening point according to 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 63 ° C. In addition, the softening point and acid value were measured, and were 110 ° C and 10 KOHmg /
It was g. The acid value was measured by a method according to JIS K0070.

75 parts by weight of styrene and 25 parts by weight of n-butyl acrylate, softening point 75.3 ° C., glass transition point 40.5
Copper phthalocyanine "Sumikapr
intCyanine Blue GN-0 ”(Sumitomo Chemical Co., Ltd.) 6 parts by weight,
15 parts by weight of the resin obtained above and 5 parts by weight of polypropylene wax "Biscol 550P" (manufactured by Sanyo Kasei Co., Ltd.) were premixed, melt-kneaded with a twin-screw extruder, cooled, and ground. 40 parts by weight of this kneaded product, 50 parts by weight of styrene, 15 parts by weight of n-butyl acrylate, and 2.5 parts by weight of 2,2'-azobisisobutylnitrile were mixed to obtain a polymerizable composition. This was added to 800 g of an aqueous colloidal solution of 4% by weight tricalcium phosphate prepared in advance in a 2 liter glass separable flask in an amount of 30% by weight. 1,200 rpm
It was emulsified and dispersed at 0 rpm for 2 minutes. Then, a 4-port glass lid was attached, a reflux cooling tube, a thermometer, a nitrogen introduction tube, and a stainless steel stirring rod were attached, and the glass was placed in an electric heating mantle heater. While continuing stirring under nitrogen, the temperature was raised to 85 ° C. and the reaction was performed for 10 hours. After cooling, dissolve the dispersion medium with 10% aqueous hydrochloric acid, filter, wash with water, dry under reduced pressure at 20 mmHg for 12 hours at 45 ° C, classify with a wind classifier, and remove the outer shell with an average particle size of 8 μm. A capsule toner which is a crystalline polyester was obtained. To 100 parts by weight of this capsule toner, 0.4 parts by weight of hydrophobic silica fine powder "Aerosil R-972" (manufactured by Nippon Aerosil Co., Ltd.) was added and mixed to obtain a capsule toner of the present invention. This is designated as toner 2. The glass transition point derived from the resin in the core material was 33.2 ° C, and the softening point of Toner 2 was 122.8 ° C.

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). 3 parts by weight of Kasei Co., Ltd .: Viscole 660P and 2 parts by weight of a charge control agent (Hodogaya Chemical Co., Ltd .: Eisenspiron Black TRH) are mixed, kneaded with a pressure kneader, cooled, and then 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 50 g of the toner produced in Capsule Toner Production Example 1 was mixed with 1 kg of a commercially available ferrite carrier in a V-type blender to obtain a developer 1. The developer 1 thus obtained was copied using the apparatus shown in FIG. 1, which was obtained by modifying a commercially available copying machine. That is, a phthalocyanine-based pigment is used as a photoconductor in the charge generation layer,
An organic photoconductor using an allylamine derivative was used for the charge transport layer, a quartz heater lamp was used as a heater for heating, and it was placed 5 cm away from the contact point between the photoconductor and the pressure roller. Further, the preheating temperature was made variable and the conveying speed was made variable so that the temperature on the surface of the recording paper could be preheated to 60 to 160 ° C. The pressure roller used for transfer / fixing is made of silicone rubber and has a diameter of 20 mmφ (aluminum cylinder with a thickness of 2 mm is coated with silicone rubber). Linear pressure is 0.1 kg / cm and peripheral speed is 35 mm / se.
I went in c. As a result, the minimum fixing temperature on paper is 92 ° C.
No fusion of the toner onto the surface of the photosensitive member was observed from 80 ° C. to 160 ° C.

The minimum fixing temperature here means that the bottom surface is 15 mm ×
Apply a load of 500 g to a 7.5 mm sand eraser, rub the image fixed five times through the fixing machine, and before rubbing, measure the optical reflection density with a Macbeth reflection densitometer, and fix according to the definition below. The temperature of the fixing roller when the rate exceeds 70%. Fixing rate (%) = (image density after rubbing / image density before rubbing) x 100

On the other hand, the toner manufactured in the above reference toner manufacturing example was mixed with a commercially available ferrite carrier to prepare a developer 2, and copying was performed in the same manner with the above modified copying machine. As a result, the minimum fixing temperature (paper surface temperature) is 14
It was 0 ° C.

Test Example 2 50 g of the toner produced in Capsule Toner Production Example 2 was mixed with 1 kg of a commercially available ferrite carrier in a V-type blender to obtain a developer 3. The developer 3 thus obtained was copied using the apparatus shown in FIG. 2, which was obtained by modifying a commercially available copying machine. That is, a polyethylene terephthalate film was used as the insulating endless film belt, a quartz heater lamp was used as a heater for heating, and the insulating endless film belt and the pressure roller were placed at a distance of 5 cm. Further, the preheating temperature was made variable and the conveying speed was made variable so that the temperature on the surface of the recording paper could be preheated to 60 to 130 ° C. The pressure roller used for transfer / fixing was an EPDM roller having a diameter of 20 mmφ (a 2 mm thick aluminum cylinder covered with an EPDM film) at a linear pressure of 0.1 kg / cm and a peripheral speed of 35 mm / sec. .
As a result, the minimum fixing temperature (paper surface temperature) was 88 ° C,
No fusing of the toner to the insulating endless film belt was observed from 80 ° C to 130 ° C.

On the other hand, using the developer 2 obtained in Test Example 1, copying was performed in the same manner with the above modified copying machine.
As a result, the fixing rate at the upper limit of 130 ° C. was 50%.

Test Example 3 A printing durability test was conducted by setting the conditions of the apparatus used in Test Example 1 as follows. That is, the same photoconductor as in Test Example 1 was used, and a surface heating element having a width of 50 mm was installed as a heater for heating at a distance of 5 cm from the contact point between the photoconductor and the pressure roller. The temperature was appropriately adjusted so that it could be preheated to 60 to 120 ° C. The pressure roller used for transfer / fixing is a Teflon-coated aluminum cylinder with a diameter of 20 mmφ and a linear pressure of 0.1 kg / c.
m, the peripheral speed was adjusted to 35 mm / sec, and the developer 1 obtained in Test Example 1 was used to perform a 10,000-sheet continuous copying test. As a result, under the fixing temperature of 90 ° C., the fixing was good and no curling or jamming of the paper was observed. Also, almost no waste toner was observed.

On the other hand, as a result of carrying out continuous copying in the same manner using the developer 2 obtained in Test Example 1, the transfer belt and the pressure roller were heavily soiled, and 100 sheets had an adverse effect on the image. did.

Test Example 4 The printing durability test was conducted by setting the conditions of the apparatus used in Test Example 2 as follows. That is, a trimethylpentene film was used as the insulating endless film belt, and a quartz heater lamp was installed as a heater for heating at a distance of 5 cm from the contact point between the insulating endless film belt and the pressure roller. The temperature was appropriately adjusted so that it could be preheated to 60 to 160 ° C. The pressure roller used for transfer / fixing is made of an aluminum cylinder coated with fluorinated ethylene propylene and has a roller diameter of 20 mmφ.
After adjusting the peripheral speed to 2 kg / cm and the peripheral speed to 35 mm / sec, a 10,000-sheet continuous copying test was conducted using the developer 3 obtained in Test Example 2. As a result, under the condition that the fixing temperature was 95 ° C., the fixing was good and no curling or jamming of the paper was observed. Also, almost no waste toner was observed.

On the other hand, as a result of continuous copying in the same manner using the developer 2 obtained in Test Example 1, the transfer belt and the pressure roller were heavily soiled, and 100 sheets had an adverse effect on the image. did.

[0078]

According to the image forming method of the present invention, any method of transferring and fixing to a recording medium can be applied without particular limitation, and the following effects can be obtained. (1) Since the toner having a good fixing property is used and the fixing is performed at a low temperature only by preheating the recording medium, the fixing can be performed only by the pressure roller, and the apparatus becomes very compact. (2) Since the heating temperature is low and the pressure roller is not directly exposed to the heat of the surface of the recording medium, the pressure roller is not required to have heat resistance. Therefore, an inexpensive elastic body can be used as the material of the pressure roller, and the life of the roller is extended. (3) Since most of the toner is transferred to the recording medium in the fixing step, there is little toner loss and no waste toner is produced. Therefore, the waste toner box and the cleaning process are simplified. As a result, it is possible to achieve cost reduction and size reduction. (4) Since the low temperature fixing toner is used, the temperature of the heating element in the fixing device can be set low, the temperature rise in the device is small, and the forced heat dissipation device in the device can be downsized. (5) Since the surface of the recording medium is heated in the preheating step, it is possible to handle thick paper. (6) Since the toner is directly fixed without passing through the electrostatic process, the conductive toner can be used, and the electrostatic induction type development which can develop by applying a low voltage becomes possible.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of an image forming method of the present invention in an electrophotographic system.

FIG. 2 is a conceptual diagram of an image forming method of the present invention in an electrostatic recording system.

FIG. 3 is a conceptual diagram of a conventional image forming method.

FIG. 4 is a conceptual diagram showing an electrophotographic charging process in the image forming method of the present invention.

FIG. 5 is a conceptual diagram showing an electrophotographic exposure process in the image forming method of the present invention.

FIG. 6 is a conceptual diagram showing a developing step in an electrophotographic system in the image forming method of the present invention.

FIG. 7 is a conceptual diagram showing a transfer / fixing process in an electrophotographic system 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 Heating heater 5a Pressure roller 5b Transfer device 6 Recording medium (recording paper) 7 Charging device 8 Cleaning device 8a Collecting toner box 9 Static eliminator 10 Toner 14 Heating Roller 21 Applying Device 22 Eliminating Device 23 Developing Device 24 Heating Heater 25 Pressure Roller 26 Recording Medium 27 Insulating Endless Film Belt 28 Cleaning Web 29 Toner 30 Supporting Roller

Claims (7)

[Claims] 1. A step of forming an electrostatic latent image, a developing step of adhering toner to the latent image to form a toner image, and a step of simultaneously transferring the formed toner image to a preheated recording medium.
An image forming method having a fixing step, wherein the 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, An image forming method, wherein the outer shell is a capsule toner made of amorphous polyester. 2. The image forming method according to claim 1, wherein a preheating temperature for the recording medium according to claim 1 is 50 ° C. or higher and 160 ° C. or lower. 3. The glass transition point of the amorphous polyester is
The image forming method according to claim 1 or 2, which has a temperature of 50 to 80 ° C. 4. The acid value of the amorphous polyester is 3 to 50.
The image forming method according to claim 1 or 2, which is (KOHmg / g). 5. The amorphous polyester is obtained by polycondensation of at least one alcohol monomer and at least one carboxylic acid monomer, and is a polyhydric alcohol unit having a valence of at least three. The image forming method according to claim 1 or 2, which is obtained by polycondensation using a polymer and / or a monomer containing a trivalent or higher polyvalent carboxylic acid monomer. 6. The encapsulated toner has a glass transition point of 10 derived from a thermoplastic resin which is a main component of a heat-fusible core material.
The image forming method according to claim 1 or 2, wherein the temperature is from about 50 ° C. 7. A capsule toner having an outer shell made of amorphous polyester, wherein the surface of a core material is coated with the amorphous polyester by an in situ polymerization method.
Or the image forming method described in 2.