JPH11242355A - Electrophotographic image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent toner from being stuck to a roller in the case of preservation at high temperature and to prevent the toner from being damaged due to running by including a resin whose glass transition temperature is equal to or above a specified value in the toner in the case of transferring a toner image formed on a photoreceptor drum by developing to a medium, and then thermally processing and fixing it on the medium. SOLUTION: A developer layer forming member 7 forming a developer layer on a developing roller 8 comes in contact with the roller 8 with proper pressure, and the toner layer 10 whose thickness of about 10 to 50 μm is formed on the roller 8. If the toner layer 10 is thin, sufficient printing density is hardly obtained, and if the layer 10 is thick, dispersion is largely and easily caused in the electrification of individual toner particles. Then, the device is provided with a developing device to perform developing control so that the thickness of the layer 10 formed on the roller 8 rotating in contact with the, photoreceptor drum 5 may be 50 μm. In the case of transferring the toner image formed on the drum 5 by developing to the medium and then thermally processing and fixing it on the medium, the resin whose glass transition temperature is >=75 deg.C is included in the toner.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming apparatus.

[0002]

2. Description of the Related Art In a conventional electrophotographic method, a photoconductive insulating layer on a photosensitive drum is uniformly charged, then the layer is exposed to light, and the charge on the exposed portion is extinguished. An electrostatic latent image is formed. A developing step of visualizing the latent image by attaching a developer containing at least a colorant (hereinafter referred to as toner) to the latent image; a transfer step of transferring the obtained visible image to a transfer material such as transfer paper; , Pressure or other suitable fixing method. Generally, the toner is subjected to various mechanical damages such as heat, friction, and contact during the operation of the device in the developing device, and the performance thereof is easily deteriorated.

More specifically, the toner is softened in the developing device by the heat generated by the temperature rise in the apparatus, and the toner is formed into a toner layer forming member (hereinafter referred to as a developing blade), a developer carrier (hereinafter referred to as a developing roller), and a toner supply roller. Etc., which can easily cause trouble. In addition, the performance as a developer is deteriorated due to mechanical stress from a developing blade, a developing roller, a toner supply roller and the like due to long-term running, and the performance as a developer is reduced.
It is difficult to maintain the life of the P cartridge.

Further, in the contact developing method, in which the developing roller is brought into contact with the photosensitive drum to perform development, the developing roller contacts the photosensitive drum with a strong pressure, so that the developing roller is exposed for a long time or at a high temperature. When the cartridge is left unattended, the toner on the developing roller that comes into contact with the photoconductor drum is deformed by the pressure between the photoconductor drum and adheres to the photoconductor drum (or the developing roller, or both), which may cause printing failure. .

Further, the toner deteriorates due to mechanical stress from a developing blade, a developing roller, a toner supply roller and the like during a long period of running, and the performance as a developer is reduced by EP.
Making it difficult to maintain over the life of the cartridge.

It is effective to provide a fan for exhausting heat in order to prevent thermal damage, but there is a problem of noise.
The advantage of the electrophotographic system may be the silence. In addition, it becomes a bottleneck in terms of cost or downsizing of the apparatus. As an approach to this from the toner side, it is conceivable to make the characteristics easy to fix and reduce the heat generation source. As an example, a toner having a capsule structure called a so-called low-temperature fixing toner has been proposed.

Further, the following attempts have been made as a method for preventing mechanical damage. That is, there has been an attempt to use a film-like developing roller or a thin pipe-like developing roller as a developing roller to reduce the mechanical stress on the toner between the developing roller and the toner. Alternatively, attempts have been made to reduce the pressure applied to the toner by reducing the pressure of the developing blade against the developing roller.

[0008]

However, the toner which is easy to fix has low mechanical strength. When the stress on the toner is reduced, the frictional force between the toner and the developing roller, the developing blade, or the like is weakened, so that the charging of the toner becomes difficult and the print quality is deteriorated. In the contact developing method, it is obvious that the stress on the toner is reduced by simply reducing the pressure of the developing roller pressed against the photosensitive drum, but this has side effects.

That is, in the present developing method, the toner is frictionally charged even in the contact area (developing area) between the developing roller and the photosensitive drum. Therefore, reducing the pressing pressure leads to a decrease in the amount of charge of the toner. This may lead to an increase or deterioration of dot and line reproducibility. Therefore, in the contact developing method, it is inevitable that a pressure equal to or more than a certain value is applied to the toner in the developing region. In this regard, it is desirable that some improvement be made from the toner side.

[0010]

The present invention employs the following structure to solve the above problems. <Structure 1> A developing device that controls development so that the thickness of a toner layer formed on a developing roller rotating in contact with the photosensitive drum is 50 μm, and the toner formed on the photosensitive drum by development When an image is transferred to a medium and then heat-treated and fixed, the toner has a glass transition temperature of 75 ° C.
An electrophotographic image forming apparatus comprising the above resin.

<Structure 2> A developing device is provided which controls development so that the thickness of a toner layer formed on a developing roller which rotates in contact with the photosensitive drum is 50 μm, and is formed on the photosensitive drum by development. In the case where the transferred toner image is transferred to a medium and then heat-treated and fixed, the outermost peripheral portion of the toner includes:
An electrophotographic image forming apparatus comprising a resin layer having a glass transition temperature of 75 ° C. or higher.

<Structure 3> A developing device is provided for controlling development so that the thickness of a toner layer formed on a developing roller rotating in contact with the photosensitive drum is 50 μm, and is formed on the photosensitive drum by development. In the case where the transferred toner image is transferred to a medium and then heat-treated and fixed, the outermost peripheral portion of the toner includes:
An electrophotographic image forming apparatus comprising a resin layer having a glass transition temperature of 85 ° C. or higher.

<Structure 4> A developing device is provided for controlling development so that the pressure contact force of the developing roller on the photosensitive drum is 2 g / mm or more and 30 g / mm or less. The developing device is formed on the photosensitive drum by development. When the transferred toner image is transferred to a medium and then heat-treated and fixed, the above toner has a glass transition temperature of 75%.
An electrophotographic image forming apparatus characterized by containing a resin having a temperature of not less than ° C.

<Structure 5> A developing device for controlling the development so that the pressure contact force of the developing roller on the photosensitive drum is 2 g / mm or more and 30 g / mm or less is provided. The developing device is formed on the photosensitive drum by development. An image forming apparatus of an electrophotographic type, wherein a resin layer having a glass transition temperature of 75 ° C. or more is disposed on the outermost peripheral portion of the toner when the transferred toner image is transferred to a medium and then heat-treated and fixed. .

<Structure 6> A developing device for controlling the development so that the pressure contact force of the developing roller on the photosensitive drum is 2 g / mm or more and 30 g / mm or less is provided. The developing device is formed on the photosensitive drum by development. An electrophotographic image forming apparatus, wherein a resin layer having a glass transition temperature of 85 ° C. or more is disposed on the outermost peripheral portion of the toner when the transferred toner image is transferred to a medium and then heat-treated and fixed. .

<Arrangement 7> In the image forming apparatus according to any one of Arrangements 1 to 6, the toner comprises at least a thermoplastic resin and a colorant as constituent materials, and comprises a polymerizable monomer having a different glass transition temperature. An electrophotographic image forming apparatus, which is a toner having a capsule structure using two or more types of bodies.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventor has disclosed an electrophotographic image forming apparatus using a developing device having a developer thickness of 50 μm or less on a developer carrier such as a developing roller. It has been found that the above problem can be solved by using a developer in which the value of the resin having the highest glass transition temperature is 75 ° C. or higher, preferably 85 ° C. or higher.

It is extremely effective that such a toner is composed of two or more kinds of resins whose resins have different glass transition temperatures, and that these resins have a capsule structure. This has also been elucidated, and the present invention has been completed.

Further, by using such a toner, the contact pressure between the developing roller and the developing blade can be set to a value necessary for the toner to obtain a sufficient triboelectric charge.
Further, it is possible to provide not only the storage reliability of the toner at a high temperature and the deterioration of the toner during running, but also an apparatus excellent in basic performance as an electrophotographic image forming apparatus.

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of an image forming apparatus suitable for carrying out this example. In FIG. 1, an image bearing member 5 (hereinafter, referred to as a charging roller) rotates in a direction indicated by an arrow B in FIG. 1 and a conductive shaft 2 rotates in a direction indicated by an arrow A in FIG. ,
(Referred to as a photosensitive drum). The dedicated DC power supply 4 charges the photosensitive drum 5 to a constant potential by applying a constant DC voltage to the contact-type charging member 1.

Next, the charged photosensitive drum 5 is exposed by a latent image writing / exposure source 6 (hereinafter, referred to as an LED head) to form an electrostatic latent image on the photosensitive drum 5 and enters a developing area. Developer carrier 8 (hereinafter referred to as developing roller)
Rotates in the direction of arrow C in the figure, and is in contact with the photosensitive drum at an appropriate pressure. Further, a developer layer forming member 7 for forming a developer layer on the developing roller 8 (hereinafter, referred to as a developing blade)
Is in contact with the developing roller 8 at an appropriate pressure,
Preferably, a toner layer 10 of about 15 to 30 μm is formed on the developing roller 8. If the toner layer 10 is thin, it is difficult to obtain a sufficient print density, and if the toner layer 10 is thick, the charging of individual toner particles tends to vary greatly.

When the charge distribution is broad, background fog is likely to occur due to insufficiently charged toner.
Therefore, it is important to uniformly frictionally charge all the toner particles in order to keep the charge amount distribution of the toner in a narrow range, and it can be said that the thinner the toner layer is, the better the necessary and sufficient density can be secured. .

The developing device having the above-described structure develops a developer (hereinafter, referred to as toner) on the electrostatic latent image. Then, the developed toner image 9 is transferred to the transfer member 11.
(Hereinafter referred to as a transfer roller). In the image forming apparatus, a residual toner collecting member 12 (hereinafter, referred to as a cleaning roller) for collecting transfer residual toner once collects the toner remaining on the photosensitive drum 5 after the transfer, for example, during paper printing or when warming up. When the development is not performed, the photosensitive drum 5 is returned to the photosensitive drum 5 by appropriate means (not shown) in the reverse of the recovery, and is again recovered into the developing device by the developing roller 8.

FIG. 2 is a schematic configuration diagram of an image forming apparatus different from FIG. The apparatus shown in this figure is provided with a cleaning blade 15 instead of the cleaning roller 12 of the apparatus shown in FIG. The toner scraped off from the photosensitive drum 5 by the cleaning blade 15 is collected in the case 16. Even in such processing, a large mechanical stress is applied to the toner.

FIG. 3 shows the relationship between the toner layer thickness, background fog and the amount of charge when the toner of this embodiment is used. FIG. 4 shows the relationship between the pressure applied to the developing roller of the developing blade and the toner layer thickness. Show the relationship. The background fog increases with an increase in the thickness of the toner layer, which indicates that this is due to an increase in insufficiently charged toner particles due to a decrease in the amount of charge. The background fog is
It is measured by the following method using a spectrophotometer Minolta CM-1000.

First, a 3M scotch tape is adhered to the same paper used for printing, and the reflectance is measured by the same colorimeter. The value at this time is assumed to be A. Next, the image forming apparatus during printing is momentarily interrupted, and the EP cartridge (developing device) is taken out. Here, a 3M scotch tape is adhered to the surface of the photosensitive drum corresponding to the end of the developing process and before the start of the transfer process, and the background fog toner attached to the surface of the photosensitive drum is removed. Next, the tape is attached to the same paper as used for printing, and the reflectance is measured by the same colorimeter. The value at this time is B. At this time, the numerical value (A-
B) (%) is defined as background fog.

In order to obtain the required print density, about 1
Although a toner layer thickness of 2 μm or more is required, the linear pressure of the developing blade at this time is 4 g / cm. On the other hand, in order to use the toner layer without causing background fog, the toner layer thickness needs to be 50 μm or less, and the linear pressure of the developing blade at this time is 0.3 g / cm.

That is, in order to satisfy high-quality printing quality, the linear pressure of the developing blade should be approximately 0.3 to 4 g / cm.
It is understood that it is important to set the value between. Such a linear pressure of the developing blade gives a large mechanical stress to the toner particles when the EP cartridge is used. In addition, when the EP cartridge is left for a long time after printing during transportation of a product or in a high-temperature environment, high pressure and high pressure are continuously applied for a long time.

In order to be able to withstand use in such an environment, it is effective to increase the molecular weight of the toner resin or increase the glass transition temperature. It's nothing more than a burden on people. In other words, this leads to an increase in the set temperature of the fixing device, and eventually to an increase in thermal damage to the toner.

Further, even if such measures are actually taken from the toner side, the effect is limited, and the burden on the fixing device is increased, and it is difficult to get out of a so-called trade-off relationship. .

Next, an example of a method for producing the toner having the capsule structure used in this embodiment will be described. Examples of the resin used for the core material and the shell material of the capsule toner in this specific example include a thermoplastic resin such as a vinyl resin, a polyamide resin, and a polyester resin.

Among the above thermoplastic resins, the monomers constituting the vinyl resin include, for example, styrene, 2,4-
Dimethylstyrene, α-methylstyrene, p-ethylstyrene, O-methylstyrene, m-methylstyrene, p
-Methylstyrene, p-chlorostyrene, styrene or styrene derivatives such as vinylnaphthalene, or 2-ethylhexyl acrylate, methyl methacrylate, acrylic acid, methyl acrylate, ethyl acrylate, n-propyl acrylate, isobutyl acrylate, Acrylic acid t
-Butyl, amyl acrylate, cyclohexyl acrylate, n-octyl acrylate, isooctyl acrylate, decyl acrylate, lauryl acrylate, stearyl acrylate, methoxyethyl acrylate, 2-hydroxyethyl acrylate, glycidyl acrylate, acrylic Phenyl acrylate, α-methyl methyl acrylate, methacrylic acid, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, amyl methacrylate, cyclohexyl methacrylate N-octyl methacrylate, isooctyl methacrylate, decyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, methoxy methacrylate Chill, 2-hydroxyethyl methacrylate, glycidyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, ethylene monocarboxylic acids and esters thereof such as diethylaminoethyl methacrylate, or ethylene, propylene,
Ethylenically unsaturated monoolefins such as butylene and isobutylene, or vinyl esters such as vinyl chloride, vinyl bromoacetate, vinyl propionate, vinyl formate and vinyl caproate, or ethylenic such as acrylonitrile, methacrylonitrile, and acrylamide Examples include substituted monocarboxylic acids or ethylenic dicarboxylic acids such as maleic acid esters and substituted products thereof, for example, vinyl ketones such as vinyl methyl ketone, and vinyl ethers such as vinyl methyl ether. These resins can be used alone or as a mixture to form the core material and the shell material.

A crosslinking agent can be added to the monomer composition constituting the resin of the core material used in this embodiment, if necessary. As an example, divinylbenzene, divinylnaphthalene, polyethylene glycol dimethacrylate,
2,2'-bis (4-methacryloxydiethoxydiphenyl) propane, 2,2'-bis (4-acryloxydiethoxydiphenyl) propane, diethylene glycol diacrylate, triethylene glycol diacrylate,
1,3-butylene glycol dimethacrylate, 1,6
-Use a general cross-linking agent such as hexylene glycol dimethacrylate, neopentyl glycol dimethacrylate, dipropylene glycol dimethacrylate, polypropylene glycol dimethacrylate, trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, tetramethylolmethane tetraacrylate, and the like. Can be. If necessary, two or more of these crosslinking agents may be used in combination.

The polymerization initiator used for producing the thermoplastic resin for the core material includes 2,2'-azobis (2,4-dimethylvaleronitrile) and 2,2'-azobisisobutyi. Lonitrile, 1,1'-azobis (cyclohexane-1-carbonitrile), 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, and other azo or diazo polymerization initiators, ie, benzoyl Peroxide, methyl ethyl ketone peroxide,
Peroxide polymerization initiators such as isopropyl peroxycarbonate, cumene hydroperoxide, 2,4-dichlorobenzoyl peroxide, lauroyl peroxide and dicumyl peroxide can be used.

In this specific example, the colorant is contained in the core material of the capsule toner, but any of the dyes and pigments used in the conventional colorant for toner can be used. Examples of the coloring agent used in this specific example include various carbon blacks produced by an acetylene black method, a thermal black method, a channel black method, a lamp black method, etc., and grafted carbon coating the surface of the carbon black with a resin. Black, Brilliant First Scarlet, Phthalocyanine Blue, Nigrosine Dye, Pigment Green B, Rhodamine-B Base,
Permanent brown FG, Solvent Red 49, etc., and mixtures thereof can be mentioned.

In this specific example, a charge control agent can be further added to the core material. The negative charge control agent to be added is not limited to the charge control agent described below, of course. "Eisen Spiron Black T
RH "(above, Hodogaya Chemical Co., Ltd.) mixed metal azo dyes" Bontron S-31 "," Bontron S-32 ",
"Bontron S-34""Varifast Black 38"
Quaternary ammonium salts such as "04" (all manufactured by Orient Chemical Co., Ltd.), for example, "COPY CHARGE NX VP"
434 "(manufactured by Hoechst), a nitroimidazole derivative copper phthalocyanine dye, a metal complex of an alkyl derivative of salicylic acid, for example," Bontron E-81 "," Bontron E-82 "," Bontron E-85 "(above, Orient Chemical Co., Ltd.) Manufactured).

The positively chargeable charge control agent is not limited to the charge control agents described below, similarly to the negatively chargeable charge control agent. For example, a nigrosine dye “oil black BS”, "Bontron N-01",
"Bontron N-07", "Bontron N-11",
"Nigrosine base EX", "Oil black SO"
A triphenylmethane dye containing a tertiary amine as a side chain, a quaternary ammonium salt compound, for example, "Bontron P-51" (manufactured by Orient Chemical Co., Ltd.), cetyltrimethylammonium bromide, "C0PYCHARGE PX VP435"
(Manufactured by Hoechst AG) and the like, such as "AFP
-B "(manufactured by Orient Chemical Co., Ltd.) and imidazole derivatives.

In the core material, if necessary, for the purpose of improving offset resistance, for example, polyolefin, fatty acid metal salt, higher fatty acid, fatty acid ester, partially saponified fatty acid ester, higher alcohol, paraffin wax, silicone oil, Any one or more kinds of offset inhibitors such as amide waxes, silicone varnishes, polyhydric alcohol esters, and aliphatic fluorocarbons may be contained.

Examples of the polyolefin include resins such as polypropylene, polyethylene, and polybutene. Examples of the above fatty acid metal salts include metal salts of maleic acid with zinc, magnesium, calcium and the like; metal salts of stearic acid with zinc, cadmium, barium, lead, iron, nickel, cobalt, copper, aluminum, magnesium and the like: Lead dibasic stearate: Metal salt of oleic acid with zinc, magnesium, iron, cobalt, copper, lead, calcium, etc .: Metal salt of palmitic acid with aluminum, calcium, etc .: Caprylate; Lead caproate Metal salts of linoleic acid with zinc, cobalt, etc .: Calcium ricinoleate: metal salts of ricinoleic acid with zinc, cadmium, etc., and mixtures thereof.

Examples of the fatty acid ester include ethyl maleate, butyl maleate, methyl stearate, butyl stearate, cetyl palmitate, ethylene glycol montanate and the like.

As the partially saponified fatty acid ester,
For example, a partially saponified calcium salt of a montanic acid ester can be used. Examples of the higher fatty acids include dodecanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, ricinoleic acid, arachinic acid, behenic acid, lignoceric acid, seracoleic acid, and the like, and mixtures thereof. Can be.

Examples of the higher alcohol include dodecyl alcohol, lauryl alcohol, myristyl alcohol, palmityl alcohol, stearyl alcohol and the like. Examples of the paraffin wax include natural paraffin, microwax, synthetic paraffin, and chlorinated hydrocarbon.

Examples of the amide wax include stearic amide, oleic amide, palmitic amide, lauric amide, behenic amide, methylene bis-stearamide, ethylene bis-stearamide,
N, N'-m-xylylenebisstearic acid amide,
N, N'-m-xylylenebis-12-hydroxydistearic acid amide, N, N'-isophthalic acid bisstearylamide, N, N'-isophthalic acid bis-12-hydroxystearylamide and the like can be mentioned.

Examples of the polyhydric alcohol ester include glycerin stearate, glycerin ricinolate, glycerin monobehenate, sorbitan monostearate, propylene glycol monostearate, and sorbitan triolate. Examples of the silicon varnish include methyl silicon varnish and phenyl silicon varnish. Examples of the aliphatic fluorocarbon include low-polymerized compounds of ethylene tetrafluoride and propylene hexafluoride.

Of the above-mentioned substances, at least a polymerizable monomer serving as a core resin, a polymerization initiator, and a colorant are mixed, and if necessary, a crosslinking agent, a wax, a charge control agent, and the like are added and mixed. The mixture is dispersed in a dispersion medium and polymerized to form core particles.

Examples of the dispersion medium include water, methanol, ethanol, propanol, butanol, ethylene glycol, glycerin, acetonitrile, acetone, isopropyl ether, tetrahydrofuran, dioxane and the like. These can be used alone or as a mixture. Further, a dispersion stabilizer can be used for the purpose of stabilizing the dispersibility of the dispersoid. All known dispersion stabilizers can be used.

As an example, polyvinyl alcohol, polystyrene sulfonic acid, hydroxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, sodium carboxymethyl cellulose, sodium polyacrylate, sodium dodecylbenzene sulfonate, sodium tetradecyl sulfate, sodium pendadecyl sulfate, sodium octyl sulfate, Sodium allyl-alkyl-polyethersulfonate, sodium oleate, sodium laurate, sodium caprate, sodium caprylate, sodium caproate,
Potassium stearate, calcium oleate, 3,3
-Disulfonediphenylurea-4,4-diazo-bis-
Sodium amino-β-napatol-6-sulfonate,
Ortho-carboxybenzene-azo-dimethylaniline, sodium 2,2,5,5-tetramethyl-triphenylmethane-4,4-diazo-bis-β-naphthol-disulfonate, tricalcium phosphate, second hydroxide iron,
Examples include titanium hydroxide and aluminum hydroxide.
These dispersion stabilizers can be used alone or in combination of two or more.

The suspension prepared as described above is maintained at 50 ° C. to 100 ° C. while stirring, so that the polymerization reaction proceeds or is completed. During or after the completion of the polymerization reaction, a second polymerizable monomer is added to the suspension to form a seed.
d Polymerize. That is, at least a vinyl polymerizable monomer and a vinyl polymer are added to an aqueous suspension of thermoplastic resin particles (hereinafter, referred to as intermediate particles) containing a colorant during or after polymerization obtained by the first polymerization. After the initiator is added and absorbed by the intermediate particles, the monomer component in the intermediate particles is polymerized.

The vinyl polymerizable monomer or the like absorbed in the intermediate particles may be added alone or may be added in advance as a water emulsion. The water emulsion to be added is obtained by emulsifying and dispersing a vinyl polymerizable monomer and a vinyl polymerization initiator in water together with a dispersion stabilizer.If necessary, a crosslinking agent, an offset preventing agent, a charge control agent, etc. It can also be contained.

A vinyl polymerization initiator used for seed polymerization,
Crosslinking agents and dispersion stabilizers may be the same as those used in the production of intermediate particles, and if necessary, for example, optimize the polymerization conditions of the shell using a water-soluble polymerization initiator. Is also possible.

The polymerizable monomer used here is desirably selected so that the glass transition temperature of the resin after polymerization is 75 ° C. or higher. That is, the glass transition temperature of the shell resin is 7
It is desirable that the temperature be 5 ° C. or higher. In the prior art, there has been no report on producing a capsule toner with a sufficiently high glass transition temperature of a shell resin in order to secure sufficient blocking resistance.

As will be described in detail in the embodiments of the present invention,
It is extremely effective to set the glass transition temperature of the resin constituting the outermost layer to 75 ° C. or higher, since the resin has sufficient blocking resistance.

By the addition of the vinyl polymerizable monomer or the water emulsion, the vinyl polymerizable monomer covers the surface of the intermediate particles and the core particles slightly swell. Then, in this state, polymerization of the polymerizable monomer component serving as a shell resin proceeds, that is, seed polymerization is performed using the intermediate particles as core particles, and a capsule toner is completed.

According to the manufacturing method as described above, the core which can be sufficiently fixed with low energy and the excellent blocking resistance even under high temperature and high pressure have extremely low fixing ability and anti-offset property. A highly balanced capsule toner can be obtained. The particle size of the capsule toner in this specific example is not particularly limited, but the average particle size is usually desirably 3 to 30 μm.

As the capsule toner in this embodiment, a fluidity improver, a cleaning improver, and the like can be used as needed. 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.

The fine silica powder is Si—O—Si
It is a fine powder having a bond, and may be any of those manufactured by a dry method and a wet method. In addition to anhydrous silicon dioxide, aluminum silicate, sodium silicate,
Any of potassium silicate, magnesium silicate, zinc silicate and the like may be used. Also, a silane coupling agent,
Fine powder of silica surface-treated with a titanium-based coupling agent, silicon oil, silicon oil having an amine in a side chain, or the like can be used.

Examples of the cleaning improver include metal salts of higher fatty acids typified by zinc stearate, fine powder of fluorine-based high molecular weight, and the like. Further, additives for adjusting developability, for example, fine powder of a polymer such as methyl methacrylate and butyl methacrylate may be used.

The capsule toner for heat and pressure fixing according to this embodiment is used alone as a developer when it contains a magnetic fine powder, and is used as a non-magnetic A one-component developer or a two-component developer mixed with a carrier can be used.

The carrier is not particularly limited.
Iron powder, ferrite, glass beads, or the like, or a resin-coated material thereof, or a resin carrier obtained by kneading magnetite fine powder or ferrite fine powder in a resin is used. The mixing ratio of the toner to the carrier is 0.5 to 20. Parts by weight. The particle size of the carrier is 15 to 500 μm
Is used.

<Example 2> The present inventor has solved the above-mentioned problems and has developed a contact developing method, more specifically, a contact developing method in which the pressure of the developing roller against the photosensitive drum is 2 to 30 g / mm. In the electrophotographic image forming apparatus having the above, the above problem is caused by using a developer in which the value of the resin having the highest glass transition temperature among the resins constituting the developer is 75 ° C. or more, preferably 85 ° C. or more. It was found that the point could be solved.

It is extremely effective that such a toner is composed of two or more kinds of resins whose resins have different glass transition temperatures, and that these resins have a capsule structure. This has also been elucidated, and the present invention has been completed.

By using such a toner, the contact pressure between the photosensitive drum and the developing roller can be set to a value necessary for the toner to obtain a sufficient amount of triboelectric charge, and the toner can be stored at a high temperature. In addition to preventing deterioration in reliability and running, an apparatus excellent in basic performance as an electrophotographic image forming apparatus can be provided. Note that, similarly to the specific example 1, the specific example 2 can be implemented by the image forming apparatus having the configuration shown in FIG.

FIG. 7 shows the relationship between the pressing pressure of the developing roller against the photosensitive drum (hereinafter simply referred to as pressing pressure) and the background fog when the toner of this example is used. FIG. 8 shows the relationship between the pressing pressure and the charge amount of the toner layer on the developing roller.

The charge quantity q (μC / g) of the toner was determined by the following equation. q = (2Vt × ε0εt) / δP (dt) ＾ 22Vt: Surface potential of toner layer on developing roller (V) ε0: Dielectric constant of vacuum 8.855 × 10 × (-12)
C / (Vm) εt: relative dielectric constant of toner layer 1.44 δ: true density of toner 1.175 × 10 ＾ 3 (Kg / m
＾ 3) P: toner layer filling rate 0.4 dt: toner layer thickness (m)

The charge amount is a value after passing through the development area without performing development. That is, it is a value calculated from Vt after the toner on the developing roller receives the charge due to frictional charging with the photosensitive drum. Further, the charge amount of the toner layer on the developing roller observed after passing through the developing blade and before passing through the area after performing the solid black printing, and the charge amount of the toner on the developing roller measured without mounting the photosensitive drum are − 3
The agreement was at μC / g. That is, the amount of charge obtained by the toner from the developing device in this experiment is -3 μm regardless of the friction with the photosensitive drum.
C / g.

In FIG. 7, the background fog decreases with an increase in the pressing pressure. From FIG. 8, the reason is that the charge amount of the toner in the developing area is increased by the increase in the pressing pressure. Recognize.

In addition, the present inventor has confirmed that when the pressing pressure is lower than 2 g / mm, the background fog rapidly increases, and when the pressing pressure is lower than 1 g / mm, the print density starts to decrease. It is considered that in contact development, additional charging of the toner in the development area is important, and if the pressing pressure is not sufficient, frictional charging is not effectively performed, and reverse charging toner is likely to be generated. It was also confirmed that when the pressing pressure was further reduced, the developing nip became unstable, the developing efficiency was lowered, and the density was lowered.

According to the study of the present inventor, it is necessary for the high-quality printing that the charge amount of the toner is approximately 10 μC / g or more in absolute value. For that purpose, it is a necessary condition that the pressing pressure is 2 g / mm or more.

On the other hand, it has been confirmed that the pressing pressure of 30 g / mm or more exerts excessive stress on the toner, so that the deterioration of the toner during running is stopped. In addition, it was confirmed that such a high pressing pressure increases the mechanical load of the EP cartridge, so that the jitter becomes remarkable. Therefore, the pressing pressure is desirably 2 g / mm or more and 30 g / mm or less.

The present inventor has reported that the charge control agent (CC
By making the amount of A) excessive, a toner having a pressure of 10 μC / g even when the pressing pressure was about 1 g / mm was prepared, and its characteristics were examined. In the system using this toner, the charge amount greatly changed due to environmental changes. A charge amount of 10 μC / g was obtained at room temperature (25 ° C. and 55 RH%) under the condition that the pressing pressure was 1 g / mm, but 20 μC at low temperature and low humidity (10 ° C. and 20 RH%).
C / g, 8μC under high temperature and high humidity (30 ℃ 80RH%)
/ G.

The above toner. Under the conditions of use, it was confirmed that there was a problem that the toner was developed in the background due to excessive charging under low temperature and low humidity. On the other hand, in combination with a toner prepared to have a charge amount of 10 μC / g under the condition that the pressing pressure is 10 g / mm, 11 μC / g under low temperature and low humidity (10 ° C. 20 RH%), and under high temperature and high humidity (30 (80 ° C./80° C.), it is 8 μC / g, and no extreme change in charge amount occurs due to environmental changes.

From the above, it has been confirmed that even if an attempt is made to maintain a large charge amount on an actual machine by adding an excessive amount of a charge control agent, practical difficulties are involved. In the electrophotographic system, since the charge of the toner depends on the phenomenon of frictional charge, it is inevitable that the charge amount changes to some extent due to environmental changes (particularly humidity).

However, as described above, the design concept of obtaining a sufficient amount of charge on an actual machine by increasing only the charging ability of the toner has an overwhelmingly large specific surface area as compared with other members. This means increasing the dependence on the toner. Therefore, it can be said that its characteristics are greatly affected by environmental changes.

The above facts indicate that the conditions of the apparatus for applying a charge to the toner are appropriate, that is, the frictional force between the various rollers (including the photosensitive drum), which is the driving force of frictional charging, is not less than a certain level. It implies that the pressing pressure must be high to some extent. By satisfying the conditions described above, a contact developing system for obtaining high-quality printed matter is completed.
In the case where the cartridge is left for a long time after printing in a high temperature environment, there is a problem that a high pressure is applied to the toner particles between the photosensitive drum and the developing roller at the same time as a high temperature for a long time.

In order to withstand use in such an environment, it is effective to increase the molecular weight of the toner resin or to increase the glass transition temperature. However, these methods are not applicable to the fixing device. It's nothing more than a burden on people. In other words, this leads to an increase in the set temperature of the fixing device, and eventually to an increase in thermal damage to the toner.

Further, even if such measures are actually taken from the toner side, the effect is limited, and the burden on the fixing device is increased, and it is difficult to get out of a so-called trade-off relationship. . This is a major reason that makes the contact development system difficult.

In this specific example, the problems of the contact developing system were solved by using the toner having the following capsule structure, and the advantage of the simple structure could be fully utilized. The manufacturing method of the toner having the capsule structure used in this specific example is the same as that of the specific example 1, and the duplicate description will be omitted.

[0078]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, Comparative Examples and Test Examples, but the present invention is not limited to these Examples and the like. << Example and Comparative Example of Specific Example 1 >><Example1> In the image forming apparatus having the configuration shown in FIGS. 1 and 2, the developing blade was set so that the toner layer thickness was 20 μm. Further, a toner having a capsule structure was produced by the method described below.

77.5 parts by weight of styrene, acrylic acid-n
-22.5 parts by weight of butyl, 1.5 parts by weight of low-molecular-weight polyethylene as an anti-offset agent, 1 part by weight of charge control agent "AIZEN SPIRON BLACK TRH" (manufactured by Hodogaya Chemical Co., Ltd.), carbon black (manufactured by Printex L Degussa)
7 parts by weight and 2,2'-azobisisobutyronitrile 1
The weight part was added, it put in the attritor ("MA-01SC", the product made by Mitsui Miike Koki Co., Ltd.), and it dispersed at 15 degreeC for 10 hours, and obtained the polymerizable composition.

Further, 180 parts by weight of ethanol in which 8 parts by weight of polyacrylic acid and 0.35 part by weight of divinylbenzene were dissolved was added, and 600 parts by weight of distilled water was added thereto to prepare a dispersion medium for polymerization. The polymerizable composition was added to the dispersion medium, and dispersed by a TK homomixer (“M type”, manufactured by Tokushu Kika Kogyo Co., Ltd.) for 10 minutes at 15 ° C. and 8000 rpm. Next, the obtained dispersion solution was transferred into a 1-liter separable flask, and reacted at 85 ° C. for 12 hours while stirring at 100 rpm in a nitrogen stream. The dispersoid obtained by the polymerization reaction of the polymerizable composition in the steps so far is referred to as an intermediate particle.

Then, 9.25 parts by weight of methyl methacrylate and acrylic acid-n were added to the aqueous suspension of the intermediate particles using an ultrasonic oscillator (US-150, Nippon Seiki Seisakusho).
A water emulsion A comprising 0.75 parts of -butyl, 0.5 parts by weight of 2,2'-azobisisobutyronitrile, 0.1 parts by weight of sodium lauryl sulfate and 80 parts by weight of water was prepared. 9 parts by weight of the water emulsion A was dropped to swell the intermediate particles. Observation with an optical microscope immediately after dropping confirmed that no emulsion droplets were observed and that swelling was completed in a very short time.

Then, the reaction was carried out at 85 ° C. for 10 hours as a second stage polymerization while stirring under nitrogen. After cooling, the dispersion medium was dissolved in a 0.5N hydrochloric acid aqueous solution, filtered, washed with water, air-dried, dried at 40 ° C. for 10 hours under reduced pressure of 10 mmHg, and classified by an air classifier to obtain capsules having an average particle diameter of 7 μm. A toner was obtained.

The glass transition temperature of the resin particles obtained before the stage of the seed polymerization was 55 ° C. That is, it can be considered that the glass transition temperature derived from the core of the capsule toner obtained in this example is 55 ° C. The glass transition temperature of the thermoplastic resin obtained when only the water emulsion A was polymerized alone was 85 ° C. That is, it can be considered that the glass transition temperature of the shell-derived resin is 85 ° C.

To 50 parts by weight of this encapsulated toner, 0.35 parts by weight of hydrophobic silica fine powder "Aerosil R-972" (manufactured by Nippon Aerosil Co., Ltd.) was added and mixed to obtain an encapsulated toner of this specific example. The toner is mounted on an EP cartridge using this toner, and subjected to a standing test at 50 ° C. for one month (assuming the preservation under the limit). The presence or absence of toner fixation was examined. FIG. 5 shows the results.

No toner adhesion or the like was observed at all on the developing blade and on the surface of the developing roller in contact with the developing blade. After the storage test, the EP with this toner
Use a cartridge for the LED printer OKI MIKROLINE1
6n, initial printing was performed, and no abnormalities in printing at a pitch derived from the circumferential length of the developing roller and the photosensitive drum were observed. A printed matter was obtained.

Thereafter, 30,000 sheets of running printing were performed with A4 size printing DUUTY 15%. The print quality at the end of the running was very high quality, which was completely the same as the initial print. FIG. 6 shows the result of observing the fluidity of the toner remaining in the EP cartridge at the end of the running. In the test performed in this example, the fluidity did not change at all from the initial stage, and the powder had high fluidity.

Example 2 Water Emulsion A in Example 1
Was prepared in the same manner as in Example 1 except that the water emulsion B was adjusted by changing the composition ratio of That is, 8.75 parts by weight of methyl methacrylate and acrylic acid-n were added to the aqueous suspension of the intermediate particles obtained in Example 1 with an ultrasonic oscillator (US-150, Nippon Seiki Seisakusho). -Butyl 1.25 parts, 2,2'-azobisisobutyronitrile 0.5 part by weight, sodium lauryl sulfate 0.1 part by weight,
A water emulsion B consisting of 80 parts by weight of water was prepared.

9 parts by weight of the water emulsion B was dropped to swell the intermediate particles. Observation with an optical microscope immediately after dropping confirmed that no emulsion droplets were observed and that swelling was completed in a very short time. Then, the reaction was allowed to proceed at 85 ° C. for 10 hours as a second stage polymerization while continuing to stir under nitrogen. After cooling, the dispersion medium was dissolved in a 0.5N hydrochloric acid aqueous solution, filtered, washed with water, air-dried,
After drying under reduced pressure of 10 mmHg at 40 ° C. for 10 hours, the powder was classified by an air classifier to obtain a capsule toner having an average particle diameter of 7 μm.

The glass transition temperature of the thermoplastic resin obtained by polymerizing only water emulsion B alone was 75 ° C. That is, the glass transition temperature of the shell-derived resin is 75
° C. This capsule toner 5
0 parts by weight of the hydrophobic silica fine powder "Aerosil R-97"
2 "(manufactured by Nippon Aerosil Co., Ltd.) was added and mixed to obtain a capsule toner of this specific example.

Using this toner, it was mounted on an EP cartridge under the same conditions as in Example 1, and subjected to a one-month standing test at 50 ° C. (assuming that the preservability under the limit was ensured). The presence or absence of toner sticking to the developing blade surface and the developing roller surface was examined. FIG. 5 shows the results.

No toner adhesion or the like was observed at all on the developing blade and on the surface of the developing roller in contact with the developing blade. After the storage test, the EP with this toner
Use a cartridge for the LED printer OKI MIKROLINE1
6n, initial printing was performed, and no abnormalities in printing at a pitch derived from the circumferential length of the developing roller and the photosensitive drum were observed. A printed matter was obtained.

Thereafter, 30,000 sheets of running printing were performed at A4 size printing DYUTY 15%. The print quality at the end of the running was very high quality, which was completely the same as the initial print. FIG. 6 shows the result of observing the fluidity of the toner remaining in the EP cartridge at the end of the running. In the test performed in this example, the fluidity did not change at all from the initial stage, and the powder had high fluidity.

Example 3 A toner having a capsule structure was manufactured by the method described below. 70 parts by weight of styrene, 30 parts by weight of n-butyl acrylate, 1.5 parts by weight of a low-molecular-weight polyethylene as an anti-offset agent, and a charge control agent "Aizen Spiron Black TRH" (manufactured by Hodogaya Chemical Co., Ltd.) 1
Parts by weight, 7 parts by weight of carbon black (manufactured by Printex L Degussa) and 1 part by weight of 2,2'-azobisisobutyronitrile were added, and an attritor ("MA-01S") was added.
C ", manufactured by Mitsui Miike Kakoki Co., Ltd.) and dispersed at 15 ° C. for 10 hours to obtain a polymerizable composition.

Further, 180 parts by weight of ethanol in which 8 parts by weight of polyacrylic acid and 0.35 part by weight of divinylbenzene were dissolved was added, and 600 parts by weight of distilled water was added thereto to prepare a dispersion medium for polymerization. The polymerizable composition was added to the dispersion medium, and dispersed by a TK homomixer (“M type”, manufactured by Tokushu Kika Kogyo Co., Ltd.) for 10 minutes at 15 ° C. and 8000 rpm.

Next, the obtained dispersion solution was transferred into a 1-liter separable flask and reacted at 85 ° C. for 12 hours while stirring at 100 rpm under a nitrogen stream. The dispersoid obtained by the polymerization reaction of the polymerizable composition in the steps so far is referred to as an intermediate particle.

Next, 9 parts by weight of the aqueous emulsion B obtained in Example 2 was added dropwise to swell the intermediate particles. Observation with an optical microscope immediately after dropping confirmed that no emulsion droplets were observed and that swelling was completed in a very short time. Then, the reaction was allowed to proceed at 85 ° C. for 10 hours as a second stage polymerization while continuing to stir under nitrogen.

After cooling, the dispersion medium was dissolved in a 0.5N aqueous hydrochloric acid solution, filtered, washed with water, air-dried, dried at 40 ° C. for 10 hours under reduced pressure of 10 mmHg, and classified by an air classifier to obtain an average particle size. A 7 μm capsule toner was obtained.

The glass transition temperature of the resin particles obtained before the stage of the seed polymerization was 40 ° C. That is, it can be considered that the glass transition temperature derived from the core of the capsule toner obtained in this example is 40 ° C. 50 parts by weight of the encapsulated toner is added to a fine powder of hydrophobic silica "Aerosil R-972" (manufactured by Nippon Aerosil Co., Ltd.).
35 parts by weight were added and mixed to obtain a capsule toner of this specific example.

Using this toner, it was mounted on an EP cartridge under the same conditions as in Example 1, and subjected to a standing test at 50 ° C. for one month (assuming the preservability under the limit), and the contact between the developing blade and the developing roller was performed. The presence or absence of toner sticking to the developing blade surface and the developing roller surface was examined. FIG. 5 shows the results.

No toner adhesion or the like was observed at all on the developing blade and on the surface of the developing roller in contact with the developing blade. After the storage test, the EP with this toner
Use a cartridge for the LED printer OKI MIKROLINE1
6n, initial printing was performed, and no abnormalities in printing at a pitch derived from the circumferential length of the developing roller and the photosensitive drum were observed. A printed matter was obtained.

Thereafter, 30,000 sheets of running printing were performed at A4 size printing DYUTY 15%. The print quality at the end of the running was very high quality, which was completely the same as the initial print. FIG. 6 shows the result of observing the fluidity of the toner remaining in the EP cartridge at the end of the running. In the test performed in this example, the fluidity did not change at all from the initial stage, and the powder had high fluidity.

<Comparative Example> 8.5 parts by weight of methyl methacrylate was added to the aqueous suspension of the intermediate particles obtained in Example 1 using an ultrasonic oscillator (US-150, Nippon Seiki Seisakusho). ,
A water emulsion C comprising 1.5 parts of n-butyl acrylate, 0.5 parts by weight of 2,2'-azobisisobutyronitrile, 0.1 parts by weight of sodium lauryl sulfate and 80 parts by weight of water was prepared. Then, a capsule toner was obtained in the same manner as in Example 1.

The glass transition temperature of the thermoplastic resin obtained by polymerizing only the water emulsion C alone was 70 ° C. That is, the glass transition temperature of the resin derived from the shell is 70.
° C. Using this toner, it was mounted on an EP cartridge under the same conditions as in Example 1, and 50
C., a one-month standing test was carried out to examine the development blade surface at the contact portion between the development blade and the development roller, and the presence or absence of toner sticking to the development roller surface. FIG. 5 shows the results.

Toner was fixed on the developing blade and on the surface of the developing roller in contact with the developing blade, and white stripes were observed on the printing surface in the horizontal direction at the cycle of the developing roller.
In addition, several white streaks were observed in the vertical direction on the printing surface. This was found to be due to the formation of a portion where the toner layer was not formed by the toner fixed on the developing blade.

Further, the toner of this example was subjected to a one-month standing test at 50 ° C. under the condition that the layer thickness was set to be 60 μm (assuming the preservability under the limit), and a contact portion between the developing blade and the developing roller was obtained. The presence or absence of toner sticking to the surface of the developing blade and the surface of the developing roller was examined. Under this condition, no toner was fixed on the developing blade and the surface of the developing roller in contact with the developing blade as in Example 1.

However, under these conditions, the background fog of the printed matter was severe, the halftone was unclear, and the print quality was not good. At this time, the fog on the photosensitive drum was 20%.

<< Example and Comparative Example of Specific Example 2 >><Example1> In the image forming apparatus having the structure shown in FIGS. 1 and 2, the pressing pressure of the developing roller against the photosensitive drum was set to 10 g / mm. did. Further, a toner having a capsule structure was produced by the method described below.

77.5 parts by weight of styrene, acrylic acid-n
-22.5 parts by weight of butyl, 1.5 parts by weight of low-molecular-weight polyethylene as an anti-offset agent, 1 part by weight of charge control agent "AIZEN SPIRON BLACK TRH" (manufactured by Hodogaya Chemical Co., Ltd.), carbon black (manufactured by Printex L Degussa)
7 parts by weight and 2,2'-azobisisobutyronitrile 1
The weight part was added, it put in the attritor ("MA-01SC", the product made by Mitsui Miike Koki Co., Ltd.), and it dispersed at 15 degreeC for 10 hours, and obtained the polymerizable composition.

Further, 180 parts by weight of ethanol in which 8 parts by weight of polyacrylic acid and 0.35 part by weight of divinylbenzene were dissolved was added, and 600 parts by weight of distilled water was added thereto to prepare a dispersion medium for polymerization. The polymerizable composition was added to the dispersion medium, and dispersed by a TK homomixer (“M type”, manufactured by Tokushu Kika Kogyo Co., Ltd.) for 10 minutes at 15 ° C. and 8000 rpm. Next, the obtained dispersion solution was transferred into a 1-liter separable flask, and reacted at 85 ° C. for 12 hours while stirring at 100 rpm in a nitrogen stream. The dispersoid obtained by the polymerization reaction of the polymerizable composition in the steps so far is referred to as an intermediate particle.

Then, 9.25 parts by weight of methyl methacrylate and acrylic acid-n were added to the aqueous suspension of the intermediate particles using an ultrasonic oscillator (US-150, Nippon Seiki Seisakusho).
A water emulsion A comprising 0.75 parts of -butyl, 0.5 parts by weight of 2,2'-azobisisobutyronitrile, 0.1 parts by weight of sodium lauryl sulfate and 80 parts by weight of water was prepared. 9 parts by weight of the water emulsion A was dropped to swell the intermediate particles. Observation with an optical microscope immediately after dropping confirmed that no emulsion droplets were observed and that swelling was completed in a very short time.

Thus, the reaction was carried out at 85 ° C. for 10 hours as a second stage polymerization while stirring was continued under nitrogen. After cooling, the dispersion medium was dissolved in a 0.5N hydrochloric acid aqueous solution, filtered, washed with water, air-dried, dried at 40 ° C. for 10 hours under reduced pressure of 10 mmHg, and classified by an air classifier to obtain capsules having an average particle diameter of 7 μm. A toner was obtained.

The glass transition temperature of the resin particles obtained before the stage of the seed polymerization was 55 ° C. That is, it can be considered that the glass transition temperature derived from the core of the capsule toner obtained in this example is 55 ° C. The glass transition temperature of the thermoplastic resin obtained when only the water emulsion A was polymerized alone was 85 ° C. That is, it can be considered that the glass transition temperature of the shell-derived resin is 85 ° C.

To 50 parts by weight of this capsule toner, 0.35 parts by weight of hydrophobic silica fine powder "Aerosil R-972" (manufactured by Nippon Aerosil Co., Ltd.) was added and mixed to obtain an encapsulated toner of this specific example. The toner is mounted on an EP cartridge using this toner and subjected to a one-month standing test at 50 ° C. (assuming preservation under the limit), and the surface of the photosensitive drum at the contact portion between the photosensitive drum and the developing roller, and the surface of the developing roller The toner was checked for the presence of toner. FIG. 9 shows the results.

No toner adhesion or the like was observed on the photosensitive drum and the surface of the developing roller in contact with the photosensitive drum. After the storage test, the EP with this toner
Use a cartridge for the LED printer OKI MIKROLINE1
6n, initial printing was performed, and no abnormalities in printing at a pitch derived from the circumferential length of the developing roller and the photosensitive drum were observed. A printed matter was obtained.

Thereafter, 30,000 sheets of running printing were performed at A4 size printing DUUTY 15%. The print quality at the end of the running was very high quality, which was completely the same as the initial print. FIG. 10 shows the result of observing the fluidity of the toner remaining in the EP cartridge at the end of running. In the test performed in this example, the fluidity did not change at all from the initial stage, and the powder had high fluidity.

<Example 2> Aqueous emulsion A in Example 1
Was prepared in the same manner as in Example 1 except that the water emulsion B was adjusted by changing the composition ratio of That is, 8.75 parts by weight of methyl methacrylate and acrylic acid-n were added to the aqueous suspension of the intermediate particles obtained in Example 1 with an ultrasonic oscillator (US-150, Nippon Seiki Seisakusho). -Butyl 1.25 parts, 2,2'-azobisisobutyronitrile 0.5 part by weight, sodium lauryl sulfate 0.1 part by weight,
A water emulsion B consisting of 80 parts by weight of water was prepared. 9 parts by weight of this water emulsion B was added dropwise to swell the intermediate particles.
Observation with an optical microscope immediately after dropping confirmed that no emulsion droplets were observed and that swelling was completed in a very short time.

Then, the reaction was carried out at 85 ° C. for 10 hours as a second stage polymerization while stirring was continued under nitrogen. After cooling, the dispersion medium was dissolved in a 0.5N hydrochloric acid aqueous solution, filtered, washed with water, air-dried, dried at 40 ° C. for 10 hours under reduced pressure of 10 mmHg, and classified by an air classifier to obtain capsules having an average particle diameter of 7 μm. A toner was obtained.

The glass transition temperature of the thermoplastic resin obtained by polymerizing water emulsion B alone was 75 ° C. That is, the glass transition temperature of the shell-derived resin is 75
° C. This capsule toner 5
0 parts by weight of the hydrophobic silica fine powder "Aerosil R-97"
2 "(manufactured by Nippon Aerosil Co., Ltd.) was added and mixed to obtain a capsule toner of this specific example.

The toner was mounted on an EP cartridge under the same conditions as in Example 1 and subjected to a one-month standing test at 50.degree. C. (assuming the preservability under the limit) at the contact portion between the photosensitive drum and the developing roller. Of the toner on the surface of the photosensitive drum and the surface of the developing roller were examined. FIG. 9 shows the results.

No toner adhesion or the like was observed on the photosensitive drum and the surface of the developing roller in contact with the photosensitive drum. After the storage test, the EP cartridge on which the toner is mounted is inserted into an LED printer Oki MIKROLINE16.
When the initial printing was performed in n, no abnormalities in printing at the pitch derived from the circumferential length of the developing roller and the photosensitive drum were observed, and there was no fogging and sufficient density and resolution, and extremely high quality A printed matter was obtained.

Thereafter, 30,000 sheets of running printing were performed with A4 size printing DUUTY 15%. The print quality at the end of the running was very high quality, which was completely the same as the initial print. FIG. 10 shows the result of observing the fluidity of the toner remaining in the EP cartridge at the end of running. In the test performed in this example, the fluidity did not change at all from the initial stage, and the powder had high fluidity.

Example 1 A toner having a capsule structure was manufactured by the method described below. 70 parts by weight of styrene, 30 parts by weight of n-butyl acrylate, 1.5 parts by weight of a low-molecular-weight polyethylene as an anti-offset agent, and a charge control agent "Aizen Spiron Black TRH" (manufactured by Hodogaya Chemical Co., Ltd.) 1
Parts by weight, 7 parts by weight of carbon black (manufactured by Printex L Degussa) and 1 part by weight of 2,2'-azobisisobutyronitrile were added, and an attritor ("MA-01S") was added.
C ", manufactured by Mitsui Miike Kakoki Co., Ltd.) and dispersed at 15 ° C. for 10 hours to obtain a polymerizable composition.

Further, 180 parts by weight of ethanol in which 8 parts by weight of polyacrylic acid and 0.35 part by weight of divinylbenzene were dissolved was added, and 600 parts by weight of distilled water was added thereto to prepare a dispersion medium for polymerization. The polymerizable composition was added to the dispersion medium, and dispersed by a TK homomixer (“M type”, manufactured by Tokushu Kika Kogyo Co., Ltd.) for 10 minutes at 15 ° C. and 8000 rpm. Next, the obtained dispersion solution was transferred into a 1-liter separable flask, and reacted at 85 ° C. for 12 hours while stirring at 100 rpm in a nitrogen stream. The dispersoid obtained by the polymerization reaction of the polymerizable composition in the steps so far is referred to as an intermediate particle.

Next, 9 parts by weight of the aqueous emulsion B obtained in Example 2 was added dropwise to swell the intermediate particles. Observation with an optical microscope immediately after dropping confirmed that no emulsion droplets were observed and that swelling was completed in a very short time. Then, the reaction was allowed to proceed at 85 ° C. for 10 hours as a second stage polymerization while continuing to stir under nitrogen. After cooling, the dispersion medium was dissolved in a 0.5N hydrochloric acid aqueous solution, filtered,
After air-drying after washing with water, 10 mmHg at 40 ° C for 10 hours
, And classified by an air classifier, and the average particle size is 7 μm.
Was obtained.

The glass transition temperature of the resin particles obtained before the stage of the seed polymerization was 40 ° C. That is, it can be considered that the glass transition temperature derived from the core of the capsule toner obtained in this example is 40 ° C. 50 parts by weight of the encapsulated toner is added to a fine powder of hydrophobic silica "Aerosil R-972" (manufactured by Nippon Aerosil Co., Ltd.).
35 parts by weight were added and mixed to obtain a capsule toner of this specific example.

Using this toner, it was mounted on an EP cartridge under the same conditions as in Example 1 and subjected to a one-month standing test at 50 ° C. (assuming the preservation under the limit), and a contact was made between the photosensitive drum and the developing roller. Of the toner on the surface of the photosensitive drum and the surface of the developing roller were examined. FIG. 9 shows the results.

No toner adhesion or the like was observed on the photosensitive drum and the surface of the developing roller in contact with the photosensitive drum. After the storage test, the EP with this toner
Use a cartridge for the LED printer OKI MIKROLINE1
6n, initial printing was performed, and no abnormalities in printing at a pitch derived from the circumferential length of the developing roller and the photosensitive drum were observed. A printed matter was obtained.

Thereafter, 30,000 sheets of running printing were performed with A4 size printing DUUTY 15%. The print quality at the end of the running was very high quality, which was completely the same as the initial print. FIG. 10 shows the result of observing the fluidity of the toner remaining in the EP cartridge at the end of running. In the test performed in this example, the fluidity did not change at all from the initial stage, and the powder had high fluidity.

<Comparative Example> 8.5 parts by weight of methyl methacrylate was added to the aqueous suspension of the intermediate particles obtained in Example 1 using an ultrasonic oscillator (US-150, Nippon Seiki Seisakusho). ,
A water emulsion C comprising 1.5 parts of n-butyl acrylate, 0.5 parts by weight of 2,2'-azobisisobutyronitrile, 0.1 parts by weight of sodium lauryl sulfate and 80 parts by weight of water was prepared. Then, a capsule toner was obtained in the same manner as in Example 1.

The glass transition temperature of the thermoplastic resin obtained when only water emulsion C was polymerized alone was 70 ° C. That is, the glass transition temperature of the resin derived from the shell is 70.
° C.

The toner was mounted on an EP cartridge under the same conditions as in Example 1 and subjected to a standing test at 50 ° C. for one month to apply the photosensitive drum surface and the developing roller surface at the contact portion between the photosensitive drum and the developing roller. Was examined for toner adhesion. FIG. 9 shows the results.

[0132] Adhesion of toner is observed on the photosensitive drum and the surface of the developing roller in contact with the photosensitive drum, and white streaks are observed on the printing surface in the cycle of the developing roller and the cycle of the photosensitive drum. Was. Further, when a similar leaving test was performed under the condition that the toner of the present example was pressed against the photosensitive drum at a pressure of 0.5 to 1 g / mm, the toner on the photosensitive drum and the surface of the developing roller in contact with the photosensitive drum was No sticking was observed.

Also, no horizontal stripes of the developing roller cycle and the photosensitive drum cycle were observed on the printed image. However, as described repeatedly, under these conditions, the photoreceptor drum fog was as high as 20 to 25%, and the print quality was as high as in Examples 1 to 5.
No. 3 was inferior.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an image forming apparatus suitable for carrying out the present invention.

FIG. 2 is a schematic configuration diagram of another image forming apparatus.

FIG. 3 is an explanatory diagram showing a relationship between a toner layer thickness, a background fog, and a charge amount.

FIG. 4 is an explanatory diagram showing a relationship between a pressing force of a developing blade to a developing roller and a toner layer thickness.

FIG. 5 is an explanatory diagram showing a result of examining whether toner adheres to the surface of a developing roller.

FIG. 6 is an explanatory diagram showing the result of observing the fluidity of toner remaining in an EP cartridge.

FIG. 7 is an explanatory diagram illustrating a relationship between a pressure of pressing a developing roller against a photosensitive drum and a background fog.

FIG. 8 is an explanatory diagram showing a relationship between a pressing pressure and a charge amount of a toner layer on a developing roller.

FIG. 9 is an explanatory diagram showing a result of examining whether or not toner adheres to the surface of the developing roller.

FIG. 10 is an explanatory diagram showing the result of observing the fluidity of toner remaining in an EP cartridge.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Contact-type charging member 2 Conductive shaft 3 Dedicated spring 4 Dedicated DC power supply 5 Photoconductor drum 6 Exposure source 7 Developer layer forming member 8 Developer carrier

Claims (7)

[Claims] A developing device configured to control development so that a toner layer formed on a developing roller rotating in contact with the photosensitive drum has a thickness of 50 μm, and formed on the photosensitive drum by development. When the toner image is transferred to a medium and then fixed by heat treatment, the toner has a glass transition temperature of 7%.
An electrophotographic image forming apparatus comprising a resin of 5 ° C. or higher. 2. A developing device for controlling development so that the thickness of a toner layer formed on a developing roller which rotates in contact with the photosensitive drum is 50 μm, and is formed on the photosensitive drum by development. An electrophotographic image forming apparatus, wherein a resin layer having a glass transition temperature of 75 ° C. or higher is disposed on the outermost peripheral portion of the toner when the toner image is transferred to a medium and then heat-treated and fixed. 3. A developing device for controlling development so that a toner layer formed on a developing roller rotating in contact with the photosensitive drum has a thickness of 50 μm, and is formed on the photosensitive drum by development. An electrophotographic image forming apparatus, wherein a resin layer having a glass transition temperature of 85 ° C. or more is disposed on the outermost peripheral portion of the toner when the toner image is transferred to a medium and then heat-treated and fixed. 4. A developing device for controlling development so that a pressure contact force of a developing roller on a photosensitive drum is 2 g / mm or more and 30 g / mm or less, and toner formed on a photosensitive drum by development is provided. An electrophotographic image forming apparatus, wherein the toner contains a resin having a glass transition temperature of 75 ° C. or more when the image is transferred to a medium and then fixed by heat treatment. 5. A developing device for controlling development so that a pressure contact force of a developing roller on a photosensitive drum is 2 g / mm or more and 30 g / mm or less, and a toner formed on a photosensitive drum by development. When an image is transferred to a medium and then heat-treated and fixed, the outermost peripheral portion of the toner has a glass transition temperature of 7%.
An electrophotographic image forming apparatus comprising a resin layer having a temperature of 5 ° C. or higher. 6. A developing device for controlling development so that a pressure contact force of a developing roller on a photosensitive drum is 2 g / mm or more and 30 g / mm or less, and a toner formed on a photosensitive drum by development. When an image is transferred to a medium and then heat-treated and fixed, the outermost peripheral portion of the toner has a glass transition temperature of 8
An electrophotographic image forming apparatus comprising a resin layer having a temperature of 5 ° C. or higher. 7. The image forming apparatus according to claim 1, wherein the toner is a polymerizable monomer having at least a thermoplastic resin and a colorant, and having different glass transition temperatures. An electrophotographic image forming apparatus characterized in that the toner is a capsule-structure toner using two or more kinds of toner.