JP2002055488A - Electrophotographic toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polymerization toner with which a toner image showing excellent light-transmitting property can be formed when the image is printed on an OHP film. SOLUTION: In the electrophotographic toner prepared by the suspension polymerization of polymerizable monomers in the presence of at least a coloring agent and polyester, the toner has a charge controlling agent fixed near the surface of the toner and further has <=15% tetrahydrofuran insoluble content.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic toner for visualizing a latent electrostatic image. More specifically, the present invention relates to a toner for electrophotography, which has characteristics such as light transmittance, low energy fixing and preservability, and good chargeability that can be used for full-color toners and OHP films.

[0002]

2. Description of the Related Art Many electrophotographic methods are known, for example, as described in US Pat. No. 2,297,691 and others. In general, in electrophotography, an electrostatic latent image is formed on a photosensitive drum, the latent image is developed with toner, and this toner image is transferred to a transfer material such as paper as necessary. The image is fixed by means such as heating and pressurization to obtain a copy.

[0003] The method of producing the toner used in the electrophotographic method is roughly classified into a pulverization method and a polymerization method. In the pulverization method, a synthetic resin, a colorant, and other additives as necessary are melted and mixed, and then pulverized and classified to obtain a toner. In the polymerization method, a colorant,
Prepare a polymerizable monomer in which various additives such as a polymerization initiator, a crosslinking agent, and a charge controlling agent are uniformly dissolved or dispersed, and then a stirrer is added to an aqueous dispersion medium containing a dispersion stabilizer. The toner is obtained by subjecting the mixture to granulation, raising the temperature, and performing suspension polymerization to obtain a toner.

An image formed by an image forming apparatus using an electrophotographic method is required to be gradually improved in definition. Conventionally, as a toner used for electrophotography, a toner obtained by a pulverization method has been mainly used. According to the pulverization method, colored particles having a wide particle size distribution are easily formed. Therefore, in order to obtain satisfactory development characteristics, it is necessary to classify the pulverized product to adjust the particle size distribution to a certain degree. However, classification has a problem that the yield is poor and the toner yield is greatly reduced. Therefore, in recent years, polymerized toners that can easily control the particle size and do not require a manufacturing process such as classification have been attracting attention. However, the conventional polymerized toner has a problem that it cannot sufficiently meet the recent demands for speeding up copying machines and printers using an electrophotographic system, energy saving, and the like. Specifically, the conventional polymerized toner is not light-transmissive for applications that require light transmissivity, such as color superimposition during copying in a full-color copying machine or an image created on an OHP film. There was a problem because it was sufficient.

In order to maintain the light transmittance of the toner, it is possible to some extent in the case of the pulverization method by employing a transparent polyester resin as a binder resin. Since a styrene acrylic resin is used as a monomer, it has been difficult to obtain transparency.

[0006] In the electrophotographic method, a step of particularly consuming energy is a fixing step after transferring the toner from the photosensitive member onto the transfer material. In this fixing step, it is necessary to fix the toner on the transfer material by heating and melting the toner.
A heating roll heated to the above temperature is used, and electric power is used as an energy source thereof. It is required to lower the heating roll temperature from the viewpoint of energy saving. To lower the temperature of the heating roll, it is necessary to fix the toner at a lower temperature than before. If a toner that can be fixed at a lower temperature than before can be used, the temperature of the heating roll can be reduced, and if the temperature of the heating roll is not reduced, the fixing time can be shortened. Responding as a whole can meet the demand for energy saving.
In order to meet these demands, it is only necessary to lower the glass transition temperature of the binder resin constituting the toner in designing the toner. However, when the toner is composed of a resin having a low glass transition temperature, during storage, transportation, or in a toner box of an image forming apparatus, the toners are likely to be blocked with each other to form an aggregate, so-called preservability cannot be secured. The problem occurs.

In recent years, it has been desired to reduce the size and cost of an image forming apparatus, and many non-magnetic one-component developing systems having a relatively simple apparatus configuration have been adopted. In this developing system, the charging of the toner greatly depends on the friction when passing through the sleeve, so that it is difficult to apply the charging compared to the toner of the two-component developer, and therefore, the toner has a charge rising property. Improvement is desired. In addition, in this developing system, the rubbing strength acts when rubbing with the sleeve, so that the toner is required to withstand physical strength. Particularly in a high-speed image forming apparatus, further improvement in strength is desired.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to form a toner image having excellent light transmittance when full-color copy is overlaid or printed on an OHP film. And to provide a polymerized toner having good storage stability and excellent charging performance.

[0009]

According to the present invention, there is provided an electrophotographic toner obtained by suspension-polymerizing a polymerizable monomer in the presence of at least a colorant and a polyester. The insoluble content is 15% or less,
An electrophotographic toner, wherein the charge control agent is fixed in the vicinity of the toner surface. The invention according to claim 2 is characterized in that the charge control agent fixed in the vicinity of the toner surface is dispersed in a wet media type in advance. The toner for electrophotography according to claim 1, wherein the toner has a volume average diameter of 1 μm or less. The invention according to claim 3, wherein the toner is pulverized by a wet media type dispersing machine. 3. The electrophotographic toner according to claim 2, wherein the charge controlling agent having a particle size of 1 μm or less is fixed near the toner surface and has light transmittance.

According to the present invention, at least the suspension polymerization of the polymerizable monomer is carried out in the presence of a colorant and a polyester resin, and functions are separately imparted to the obtained electrophotographic toner. As a result, it is possible to achieve low energy fixing property, uniform melting property at the time of fixing, light transmittance, and pseudo encapsulation with a polyester resin to effectively act on the low energy fixing property and uniform melting property of the internal resin. This makes it possible to achieve both a reduction in thermal characteristics and a heat-resistant storage property.
Further, by making the content of the internal resin insoluble in tetrahydrofuran at 15% or less, it became possible to obtain good light transmittance.

The polymerizable monomers and colorants used in the present invention include the following.

Examples of the polymerizable monomer include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene, p-ethylstyrene, and p-methylstyrene.
Phenylstyrene, p-chlorostyrene, 3,4-dimethylstyrene, 2,4-dimethylstyrene, pn-butylstyrene, p-tert-butylstyrene, pn
-Hexylstyrene, pn-octylstyrene, p-
Styrene such as n-nonylstyrene and pn-decyl and derivatives thereof; ethylenically unsaturated monoolefins such as ethylene, propylene, butylene and isobutylene; organic acid vinyl esters such as vinyl acetate, vinyl propionate and vinyl benzoate Acrylic acid, methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, n-propyl acrylate, n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, acrylic acid Acrylic acid and derivatives thereof such as 2-chloroethyl and phenyl acrylate: methacrylic acid, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, n-methacrylic acid
-Butyl, isobutyl methacrylate, n-methacrylate
Methacrylic acid such as octyl, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate and the like; vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether and the like Vinyl ethers:
Vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, vinyl isopropenyl ketone; N-vinyl compounds such as N-vinyl pyrrole, N-vinyl carbazole, N-vinyl indole, N-vinyl pyrrolidone; vinyl naphthalenes; acrylonitrile; Examples include methacrylonitrile, acrylamide and the like. These polymerizable monomers can be used alone if necessary,
Also, two or more kinds can be used in combination. In particular, among the polymerizable monomers, a resin obtained by using styrene or a styrene derivative alone or by mixing with another monomer shows relatively good resin strength, and is used as an electrophotographic toner. It is preferable because the developing characteristics and durability when used can be improved.

Known coloring agents can be used.
For example, black colorants such as carbon black, acetylene black, lamp black, channel black, aniline black, etc., and chromatic nigrosine dyes, aniline blue, calco oil blue, chrome yellow, ultramarine blue, Dupont oil red, quinoline yellow, Methylene blue chloride, phthalocyanine blue, matakite green oxalate, lamp black, rose bengal, iron black, rhodamine lake pigment, azo lake pigment, iron oxide, titanium oxide, barium sulfate, etc.
Alternatively, a mixture thereof and the like can be mentioned.

The colorant is used in an amount of 1 to 40 parts by weight, preferably 3 to 20 parts by weight, based on 100 parts by weight of the polymerizable monomer. In the present invention, in order to obtain a toner using a polymerization method, it is necessary to pay attention to the polymerization inhibitory property and the aqueous phase migration property of the colorant, preferably by surface modification, for example, a substance having no polymerization inhibitory property It is better to perform a hydrophobic treatment. In particular, dyes and carbon black often have polymerization inhibitory properties, so care must be taken when using them. As a preferable method of surface-treating the dye-based colorant, a method of preliminarily polymerizing a polymerizable monomer in the presence of these dyes is exemplified. If the amount of the coloring agent is less than 1 part by weight, the coloring effect is insufficient, and if it is more than 40 parts by weight, the dye-based coloring agent inhibits polymerization and cannot be used.

The polyester used in the present invention may be any polyester that is soluble in the polymerizable monomer. For example, Mitsubishi Rayon's product name FC-89
0, NCP-004 manufactured by Nippon Carbide Co., Ltd., NCP-005 manufactured by Nippon Carbide Co., Ltd., or a weakly crosslinked polyester can be used. Specific polyester synthetic materials are as described below.

2 used in the polyester resin of the present invention
The following are examples of the valent alcohol component. That is, diethanolamine, ethylene glycol, diethylene glycol, propylene glycol, isoprene glycol, octanediol, 2,2-diethyl-
1,3-propanediol, spiro glycol, neopentyl glycol, 1,3-butanediol, 1,4-
Butanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,6-hexanediol, hexylene glycol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, hydrobenzoin, Examples thereof include bis (β-hydroxyethyl) terephthalate, bis (hydroxybutyl) terephthalate, polyoxyethylenated bisphenol A, polyoxypropylene-modified bisphenol A, polyoxyethylenated biphenol, and polyoxypropylene-modified biphenol.

Examples of the divalent carboxylic acid component include fumaric acid, maleic acid, succinic acid, itaconic acid, mesaconic acid, citraconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, and cyclohexenedicarboxylic acid. Acid, adipic acid, sebacic acid,
Dodecane diacid, 1,12-dodecane dicarboxylic acid, eicosane diacid, azelaic acid, brassic acid, naphthalenedicarboxylic acid, biphenyl-4,4'-dicarboxylic acid,
2,3-piperazine dicarboxylic acid, iminodicarboxylic acid, imidazole-4,5-dicarboxylic acid, piperidine dicarboxylic acid, pyrazole dicarboxylic acid, N-methylpyrazole dicarboxylic acid, N-phenylpyrazole dicarboxylic acid, pyridine dicarboxylic acid, carbazole −3,
6-dicarboxylic acid, 9-methylcarbazole-3,6-
Examples thereof include dicarboxylic acid, carbazole-3,6-dibutyric acid, carbazole-3,6-γ, γ′-diketobutyric acid and acid anhydrides and lower alkyl esters thereof.

The trihydric or higher polyhydric alcohol component includes
Sorbitol, 1,2,3,6-hexanetetrol,
1,2,6-hexanetriol, 1,4-sorbitan, pentaerythritol, dipentaerythritol,
Tripentaerythritol, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, diglycerol, 2-methylpropanetriol,
2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, 1,3,5-
Examples are trihydroxybenzene and the like.

The trivalent or higher carboxylic acid component includes trimellitic acid, 1,2,4-cyclohexanetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 2,5,5
7-naphthalenetricarboxylic acid, pyridinetricarboxylic acid, pyridine-2,3,4,6-tetracarboxylic acid,
Examples thereof include 1,2,7,8-tetracarboxylic acid and butanetetracarboxylic acid, and acid anhydrides and lower alkyl esters thereof can be used.

The polyester resin used in the present invention comprises 2
A divalent alcohol component, a divalent carboxylic acid or an acid anhydride thereof or a lower alkyl ester component thereof, and, if necessary, a trihydric or higher polyhydric alcohol and a trivalent or higher polyhydric carboxylic acid or an acid anhydride thereof or The lower alkyl ester component is obtained by placing the mixture in a four-necked round-bottom flask equipped with a stirrer, a condenser and a nitrogen gas inlet tube, and performing a polycondensation reaction at a temperature of 180 to 260 ° C. while introducing nitrogen gas. 10 mmHg inside the reaction system if necessary
The pressure may be reduced under the following vacuum to accelerate the reaction. At the time of the reaction, an esterification catalyst such as zinc oxide, dibutyltin oxide, tetrabutoxytitanate, and p-toluenesulfonic acid may be used. Further, the linear polyester resin which is a low melting point compound is composed of the above-mentioned dihydric alcohol component and dihydric carboxylic acid or its anhydride or its lower alkyl ester component, and is produced by the same synthesis method as the above-mentioned polyester resin. can get.

In the toner according to the present invention, a release material can be added to prevent the offset phenomenon on the fixing roll. As the release material used in the present invention, as the ester wax, carnauba wax, rice wax, candelilla wax, wood wax, jojoba oil, beeswax, lanolin, montan wax, ozokerite, ceresin, soybean hardened oil, Rapeseed hardened oil, castor hardened oil, and the like, and as the olefin wax, polyethylene,
Polypropylene, Fischer-Tropsch wax,
α-olefin maleic anhydride and / or maleic anhydride copolymer, petroleum wax such as paraffin wax, microwax, petrolatum and the like. Specifically, ester wax (produced by Nippon Shokubai Co., Ltd.)
Trade name ST-100).

In the present invention, various metal complexes and quaternary ammonium salts used in ordinary electrophotographic toners can be used as the charge control agent for immobilization near the toner surface. In order to maintain transparency that can be used for full-color toner and OHP, a colorless or pale-colored charge control agent is preferable. For example, salicylates (trade name: Bontron E-81, manufactured by Orient Chemical Co., Ltd.) and the like can be mentioned.

The charge control agent is desirably used after being pulverized in advance. For example, 800 g of methanol is put into a 2000 ml beaker, and 200 g of Bontron E-81 (trade name, manufactured by Orient Chemical Co., Ltd.) is put into this. This is 50
The mixture was stirred with a stirring blade of mmφ. This is subjected to a dyno milling process using a media type disperser. When the particle diameter of the treated charge control agent was measured by an electron microscope, it was found to be 1 μm or less.

The polymerization initiator used in the present invention is preferably soluble in a polymerizable monomer. Examples of such a polymerization initiator include 2,2'-azobis- (2,4-dimethylvaleronitrile), 2,2'-azobisisobutyronitrile, and 1,1'-azobis (cyclohexane-1).
-Carbonitrile), azo or diazo polymerization initiators such as 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, azobisisobutyronitrile, benzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl Examples include peroxide polymerization initiators such as peroxycarbonate, cumene hydroperoxide, 2,4-dichlorobenzoyl peroxide, lauroyl peroxide, α-cumyl peroxide, and α-cumyl peroxystearate. If necessary, a water-soluble initiator such as ammonium persulfate or potassium persulfate may be used in combination. The amount of the polymerization initiator to be used is generally 0.1 to 20 parts by weight, preferably 1 to 10 parts by weight, based on 100 parts by weight of the polymerizable monomer. If the amount of the polymerization initiator is less than 0.1 part by weight, the polymerization time may be long, and the molecular weight of the polymerization toner may be too high. On the other hand, if the amount of the polymerization initiator exceeds 20 parts by weight, the molecular weight of the polymerized toner may be too low, which is not preferable.

In the present invention, a known crosslinking agent such as divinylbenzene may be added to the polymerizable monomer in order to improve the heat-resistant storage stability and durability.
01 to 1.0% by weight. When the content is less than 0.001% by weight, the internal aggregation of the toner at the time of fixing is reduced, and the non-offset temperature range cannot be ensured. .

In the method for producing a toner of the present invention, generally, a colorant,
Components necessary for toner such as a release agent, a charge control agent, a cross-linking agent and other additives, for example, an organic solvent added to reduce the viscosity of a polymer formed by a polymerization reaction, a dispersant, etc., and a homogenizer are appropriately added. The monomer system is uniformly dissolved or dispersed by a dispersing machine such as a ball mill, a colloid mill, and an ultrasonic dispersing machine, and suspended in an aqueous phase medium containing a suspension stabilizer. At this time, a desired toner particle size is obtained by using a high-speed disperser such as a high-speed stirrer or an ultrasonic disperser. The polymerization initiator may be added at the same time as the other additives are added to the polymerizable monomer, or may be added immediately before suspension in the aqueous phase medium. After the granulation, stirring may be performed using a normal stirring blade to such an extent that particles are prevented from floating and settling.

In the suspension polymerization method of the polymerizable monomer in the present invention, a surfactant known as a suspension stabilizer or an organic
Inorganic dispersants can be used. Among them, inorganic dispersants are preferable because harmful ultrafine powders are not easily generated, and are relatively stable even when the reaction temperature is changed. Examples of such inorganic dispersants include polyvalent metal phosphates such as calcium phosphate, magnesium phosphate, aluminum phosphate and zinc phosphate, carbonates such as calcium carbonate and magnesium carbonate, and inorganic salts such as calcium sulfate and barium sulfate. And inorganic hydroxides such as calcium hydroxide, magnesium hydroxide, aluminum hydroxide, silica, and alumina. The amount of these inorganic dispersants added to water is preferably 0.5 to 20 parts by weight based on 100 parts by weight of water. If the amount is less than 0.5 part by weight, it is difficult to obtain a polymerized toner having a small particle diameter. On the other hand, when the amount is more than 20 parts by weight, the viscosity of the aqueous phase increases, so that it is difficult to obtain a polymerized toner having a small particle size, and
It is difficult to obtain a polymerized toner having a uniform particle size. Sodium dodecylbenzene sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, sodium octyl sulfate, and olein are used as suspending aids in order to stabilize the monomer composition suspended in the aqueous phase and obtain a polymerized toner having uniform particles. It is preferable to add a surfactant such as sodium silicate, sodium laurate, and sodium stearate to the aqueous phase. The addition amount is 0.00 parts by weight with respect to 100 parts by weight of the aqueous phase.
5 to 0.05 parts by weight is preferred. If the amount is less than 0.005 parts by weight, the effect of uniformly dispersing the suspension stabilizer is small, and the particles tend to be large. In the case of a component-based toner, toner adheres to the carrier, and in the case of a non-magnetic one-component toner, the toner is fused to the blade surface, which is not preferable. After the polymerization, the inorganic dispersant is dissolved with an acid or alkali,
It can be almost completely removed. The toner is obtained by dispersing the dispersed phase in a continuous phase using an aqueous medium using a stirring means and performing a polymerization reaction.

In this case, as a stirring means for dispersing the dispersed phase into the continuous phase, a stirring means conventionally used in suspension polymerization methods such as a turbine type stirrer can be used. The polymerization reaction is usually performed at a polymerization temperature of 50 ° C. or higher, and the temperature is set in consideration of the decomposition temperature of the polymerization initiator. The water tank is mainly composed of water. As the organic medium, methanol, ethanol, 2-methoxyethanol, propanol, butanol, benzene, toluene, tetrahydrofuran, acetone and the like can be used. The mixing ratio between the dispersed phase and the continuous phase is from 1: 1 to 1: 1.
0 is preferable, and the ratio is more preferably 1: 2 to 1:10. When the ratio of the continuous phase to the dispersed phase 1 is less than 1, a suspension cannot be obtained, so that it is difficult to obtain toner particles. When the ratio of the continuous phase to the dispersed phase 1 is more than 10, a polymerizable monomer is used. Productivity per unit time may be poor due to small body mass. In the present invention, in order to control the tetrahydrofuran insoluble content of the toner to 15% or less, the addition amount of a crosslinking agent such as divinylbenzene is reduced, and preferably 1% by weight or less based on the polymerizable monomer.

In the present invention, as a method for fixing the charge controlling agent near the toner surface, the monomer composition is suspended and weighted to obtain colored particles, and then the colored particles are suspended in an aqueous medium. The charge control agent is added to the suspension and stirred. By performing this treatment, the charge control agent adheres to the surface of the colored particles. Next, the colored particles having the charge control agent attached thereto are removed from the suspension, washed with dilute sulfuric acid and water, and dried with a vibration-type dehydration dryer to obtain the electrophotographic toner of the present invention. it can. The colored particles to which the charge control agent has been attached are dried by a vibrating dehydration dryer so that the charge control agent is fixed to the surface of the colored particles.

As another method for fixing the charge control agent on the surface of the colored particles, first, the monomer composition is subjected to suspension polymerization to obtain the colored particles, and then the colored particles are taken out of the suspension. Wash with dilute sulfuric acid and water and dry with a vibratory dehydrator. Next, after drying is completed, the colored particles and the charge controlling agent are stirred by the impact type impacting means, whereby the toner for electrophotography of the present invention comprising the colored particles having the charge controlling agent fixed on the surface can be obtained.

Japanese Patent Application Laid-Open No. 62-8 / 1987 describes an impact-type hitting means.
The method disclosed in Japanese Patent No. 3029 can be used. Further, as the impact type impacting means, a device called a surface reformer also corresponds. Examples of the surface reforming machine include a hybridization system manufactured by Nara Machinery Co., Ltd., a mechanofusion system manufactured by Hosokawa Micron Corp., and a surf fusion system manufactured by Nippon Pneumatic Co., Ltd.

[0032]

Next, the present invention will be described specifically with reference to examples and comparative examples. <Preparation of Charge Control Agent Dispersion A> 200 g of a metal-containing salicylate (trade name: E-81, manufactured by Orient Chemical Co., Ltd.) was placed in a 2,000 ml beaker, 800 g of methanol was added, and the mixture was stirred. This stirred liquid is pumped at 100 ml / mi.
n to DYNO-MILL. DYNO-MIL
For L, a 600 ml grinding container (for continuous use) was attached, and a 0.02 mm distance piece was used. Further, 0.5 mmφ glass beads were used.
After passing through the mill, the stirring liquid was dispersed in a beaker for 2 hours in a continuous manner to obtain a charge control agent A. The volume average particle size of the charge control agent after the dispersion treatment was measured by a laser diffraction particle size distribution analyzer (LEEDS & NORTHRUP INTRUMENTEN).
It was 0.32 μm when measured using a microtrack (trade name, manufactured by TS Corporation). The solid content concentration of the charge control agent was 20%.

<Preparation of Dispersion Phase> (Dispersion Phase A): After 600 g of n-butyl acrylate was added to 1400 g of styrene, 120 g of a cyan pigment (trade name KET-118, manufactured by Dainippon Ink Co., Ltd.) was further added, followed by polyester. Resin (NCP manufactured by Nippon Carbide Co., Ltd.)
-004) was added and dispersed well using an ultrasonic dispersing machine. 25 g of N, N'-azobisisobutyronitrile and 4 g of divinylbenzene (DVB) (0.2% by weight based on the monomer) as a cross-linking agent were added to this dispersion, and stirred and dissolved. (Dispersed phase B): A dispersed phase was obtained under the same conditions as in Dispersed phase A, except that the crosslinking agent DVB was added to the dispersed phase A in an amount of 1.2% by weight based on the monomer. (Dispersed phase C): Except that 20 g of a metal complex-based charge control agent (trade name: E-81, manufactured by Orient Chemical Industries) and 0.5% by weight of a crosslinking agent DVB based on the monomer are added to the dispersed phase A. A dispersed phase was obtained under the same conditions as for dispersed phase A.

<Preparation of continuous phase> (Continuous phase A): Tricalcium phosphate (trade name: TCP-10, manufactured by Taihei Chemical Industry Co., Ltd.) 10,000 g in water 10,000 g
0 g and 8 g of sodium dodecyl sulfate are added and stirred well.

Example 1 After mixing (dispersed phase A) and (continuous phase A), 10,000 was mixed using a TK homomixer (high-speed dispersing machine manufactured by Tokushu Kika Kogyo Co., Ltd.).
Granulation was performed at 0 rpm for 10 minutes. Polymerization was carried out at 80 ° C. for 7 hours while stirring the obtained suspension / dispersion liquid to such an extent that droplets did not settle. After cooling the polymer particles obtained above, tricalcium phosphate on the surface of the polymer particles was removed with dilute nitric acid, washed with water until the washing solution became neutral, filtered, and dried to obtain a dry powder toner. . 100 g of the charge control agent dispersion liquid A was added thereto, and the mixture was sufficiently stirred with a Henschel mixer. Further, the toner was treated with a hybridizer to completely fix the charge control agent on the toner surface to obtain the toner of Example 1.

Example 2 A toner of Example 2 was obtained under the same conditions as in Example 1 except that the charge control agent dispersion A was added to the suspension after the polymerization.

Comparative Example 1 A comparative toner was obtained under the same conditions as in Example 1 except that the dispersed phase A was changed to the dispersed phase B.

Comparative Example 2 A toner for comparison was obtained under the same conditions as in Example 1 except that the charge control agent dispersion A was not added.

Comparative Example 3 A comparative toner was obtained under the same conditions as in Example 1 except that the dispersed phase A was changed to the dispersed phase C and the charge control agent dispersion A was not added.

Each of the obtained toners of Examples and Comparative Examples was tested by the following evaluation methods, and the obtained results are shown in Table 1.

[0041]

[Table 1]

(Tetrohydrofuran Insoluble Content) The tetrohydrofuran insoluble content of the toner composition was measured by weighing 1.0 g (W1), putting it in a thimble filter paper, and passing it through a Soxhlet extractor.
Using 2000 ml of tetrahydrofuran as a solvent, 6
Time extracted. Tetrohydrofuran extraction cycles in the Soxhlet extractor were about four and one rate. After evaporating the tetrahydrofuran-soluble component extracted with tetrahydrofuran, the solution was dried under reduced pressure at a temperature of 100 ° C., and the weight (W2) of the tetrahydrofuran-soluble component was weighed. The proportion of insolubles in tetrahydrofuran (THF) was determined by the following equation. THF insoluble matter (%) = (W1-W2) / W1

(Light transmission) On an OHP film sheet,
A toner is uniformly placed at 0.45 mg / cm 2, and a commercially available copying machine (Phase, Sony Tektronix)
r550J), the sheets passed through a fixing device mounted thereon, and the translucency of each toner fixed on these sheets was evaluated. A sample which is completely translucent without turbidity is indicated by ○, and a case where it is not practical is indicated by ×.

(Charge Amount) Using a non-magnetic one-component developing device having a metal sleeve having a diameter of 20 mm and a resin blade, the sleeve was rotated at a linear speed of 250 mm / min for 1 minute to charge the toner. At the same time as connecting the electrode for measuring the amount of blow-off charge to the developing device, the toner on the sleeve is sucked. The amount of charge generated at this time and the amount of toner suction were measured, and the amount of charge was calculated by the following equation. Charge amount (μc / g) = charge amount (μc) / amount of suction toner (g)

[0045]

According to the present invention, in a toner comprising a polyester, a polymer of a polymerizable monomer, and a colorant, a transfer, electrostatic, and latent image fixed near the surface of the toner with the charge control agent added thereto is removed. Since the (image) becomes fine and the content of the toner insoluble in tetrahydrofuran is as small as 15% or less, it is possible to easily provide a product having good light transmittance.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03G 9/08 384 (72) Inventor Haruo Okutani 3-1, Yosobahama-cho, Shizuoka-shi, Shizuoka Prefecture F-term in paper mill technical laboratory (reference) 2H005 AA01 AA08 AB02 AB06 AB09 AB10 CA04 CA08 CA17 DA01 EA05 EA07

Claims (3)

[Claims] 1. An electrophotographic toner obtained by suspension-polymerizing a polymerizable monomer in the presence of at least a colorant and a polyester, wherein the toner has a tetrahydrofuran-insoluble content of 1%.
5% or less, wherein the charge control agent is fixed near the surface of the toner. 2. The method according to claim 1, wherein the charge control agent immobilized in the vicinity of the toner surface is pulverized in advance by a wet media type disperser, and has a volume average diameter of 1 μm or less.
The toner for electrophotography according to 1. 3. The electrophotographic toner according to claim 2, wherein the charge controlling agent having a volume average diameter of 1 μm or less is fixed near the toner surface and pulverized by a wet media type disperser.